North American Green is
leading the erosion control
industry with an advanced
line of performanceguaranteed temporary and
permanent rolled erosion
control products to alleviate
tough erosion control and
vegetation establishment
problems. Through our stateof-the-art manufacturing
facility, we ensure the highest
product quality.
Our temporary erosion
control blankets are ideal for
protecting and revegetating
slopes and drainage swales
from 2 months to 36 months.
Depending on your erosion
control needs these blankets
are available with either
photodegradable synthetic or
100% biodegradable “leno”
woven jute netting and your
choice of straw,
straw/coconut, or coconut
fibers. While all North
American Green erosion
control blankets provide
exceptional erosion control,
our 100% biodegradable
blankets utilize jute netting
that absorbs water, allowing
them to contour to the soil
surface for increased erosion
control capabilities.
For tougher applications, we
offer the Vmax3 Series of
permanent composite turf
reinforcement mattings, and
the P300 permanent turf
reinforcement mat. These
products can extend the
erosion resistance of
vegetation up to that of 30inch rock riprap… allowing
employment of vegetation on
severe slopes with heavy
runoff, channels experiencing
critical high shear stress
flows, and shorelines.
An important new product in
our industry-leading erosion
and sediment control line is
the SedimentSTOP™
Biodegradable Filtration
System. Designed for use in
disturbed sites with
unprotected topsoil,
particularly sloping areas,
SedimentSTOP is a
lightweight, easy to handle
product that filters sediment
from stormwater runoff,
providing superior sediment
protection for a wide variety
of applications.
How the Urinary Bladder Works
The urinary bladder is round, ball-shaped, muscle with a
delicate membrane on the inside surface. Most of the time the
bladder muscle is "at rest" and urine easily flows into the
bladder from the ureters which drain the kidneys. There is little
or no pressure inside the bladder during this period of muscle
relaxation.
Urine drains from the bladder and out of the body through the
urethra. A second muscle - the sphincter - completely surrounds
and constricts the urethra. The urinary sphincter muscle is
active or
"contracted"
most of the
time thus
preventing
urine from
constantly
draining from
the bladder.
Normal filling
and emptying
of urine from
the bladder involves sophisticated
neurological [nervous system]
involvement of the brain, spinal cord,
pelvic nerves and both the bladder and
sphincter
muscles.
During filling
of the bladder
the bladder
muscle is
relaxed and
the urethral
sphincter is
contracted.
Just the
opposite
occurs during normal urination. During
urination the bladder muscle contracts increasing pressure in
the bladder. At the same time the sphincter muscle relaxes. As
pressure increases inside the bladder and pressure drops inside
the urethra urine flows out of the body.
The bladder and urethral sphincter muscles are similar to other
muscles in the body. They may become less powerful with time.
They also are subject to spasm. Infection, stones, and trauma
from tubes or catheters are examples of phenomena that may
induce contraction or spasm of the bladder muscle. Such
contractions may give the patient an "urgent need to urinate".
Proper function of the bladder requires sophisticated
coordination of the bladder and urethral sphincter muscles. The
coordination is provided by the neurological system and
involves the brain, spinal cord and pelvic nerves -- as well as
the two muscles.
Aging and many major and minor neurological problems
contribute to abnormal bladder function. As muscles age their
strength may decline, but their sensitivity seems to increase.
Older muscles seem to have a lower threshold for irritation or
stimulation. For example, small volumes of urine may stimulate
a desire to urinate in the older individual whereas the same
small volume may not stimulate an urge in a younger person,
Moreover, a less powerful bladder muscle will generate less
pressure in the bladder and sometimes the bladder does not
empty completely. A variety of factors affect nerve sensitivity
and muscle power.
SAND DUNE FORMATION-WIND EROSION CONTROL-DUST
CONTROL PRODUCTS
INTRODUCTION
Erosion of surface soils due to the action of wind has become a major problem in arid and
semi arid areas across the world. Advancing deserts under the action of wind are
rendering arable and fertile land, infertile.
The importance of coastal dunes and their impact on the ecology is now clearly
recognized. Coastal dunes help save lives and property during cyclone and storms by
breaking the force of waves that lash the coast.
Suspended particles in the air have been known to affect health of humans and
governments in various countries have enacted legislation to control them.
Florafab™ Geotextiles made from natural fibre yarn such as coir, jute, etc. can be used
for wind erosion control, dust control, sand dune formation and stabilization.
PRODUCTS
Jute
Light-weight jute fabrics have been found useful in dust control. The hairiness of the
yarns and the size of the openings in the mesh determine the size and the amount of
suspended matter entrapped. Generally the material is used as a fence installed vertical to
the ground with the help of wooden stakes or metal rods The products can also be used as
covers for waste dumps, open cast mines, sand dune stabilisation and construction sites.
Products: FJ-6, FJ-7, FJ-8, other products as per buyer’s specs
Coir
Coir products last longer than jute but they are heavier and can be used in critical areas
like sand dune formation, sand dune stabilisation and for coastal protection works.
Products: FC-12, FCNN-1.
FC-12
The design is such that the geotextile combines the features of a sand fence and a netting
laid flat on the surface into a single product.
The width and mesh size of the geotextile varies as per the requirement of the place of
application. A part of the width of the geotextile has closely placed warp and weft yarns
to produce a tighter mesh while the rest of the width has warp yarns placed at a distance
to give a loose mesh effect with large openings. The function of the tighter mesh,
installed perpendicular to the ground surface using metal or wood stakes is to trap
saltating sand particles, while allowing the wind to pass through, slowly. This also
reduces the ground wind speed. This part also gives the required shade for the plants
growing through the loose-netted part of the geotextile.
The loose, spacey mesh part of the geotextile is placed flat on the ground. Saplings are
planted through the open spaces of the net. Seeds may also be placed below this portion
of the geotextile. A layer of natural fibre or straw may be placed over the net (optional).
This layer retains moisture and prevents the seeds from being blown away by the wind.
The net and the fibre layer are stapled to the ground.
Strips of these nets laid parallel to each other help form rows of shelter-belts and
windbreaks and remains till vegetation takes over their functions.
FCNN-1.
Light-weight Nonwoven coir needle punched geotextiles are ideally suited for covering
sand dunes and help in quick establishment of vegetation. They can also be used in other
kinds of soil where wind erosion is a problem. The matting absorbs water up to around
three times its own weight. The coir degrades to form an organic mulch storing water in it
for use by plants during dry seasons. The geotextile can be pre-seeded as per buyer’s
specifications. The product is available in width size of 2.2m and lengths of 20m per roll.
Rolled Erosion Control Products (RECP)
2002-2003 NTPEP Application for Bench-Scale Testing
~~~1st CYCLE DEADLINE EXTENDED TO JAN. 15, 2003~~~
(Source: ECTC) The enormous problem of uncontrolled
soil movement by water and wind has created the erosion
control industry. The magitude of the problem is often
overlooked by those unfamiliar with the impact of erosion. As a
single example, sediment the by-product of erosion) accounts
for more than two-thirds of all pollutants entering U.S.
waterways. Annual spending in the U.S. for mitigation of
erosion and sedimentation is estimated at $13 billion.
.
.
The erosion control industry consists of a broad range of diverse professions and specialties,
including hydroseeders, mat and blanket manufacturers, consulting engineers, landscapers and even
earth moving contractors. All stake claims to separate or interrelated segments of this market. This
army of professionals have two objectives in mind; the prevention of soil erosion, and the trapping of
sediment before it enters the waterways..
.
One of the most rapidly growing and "high tech" segments within the industry has been the erosion
control mat and blanket market. Rolled erosion control products (i.e. mats and blankets) were first
used in the form of jute mattings imported from Asia, but have quickly evolved to include organic
fiber-filled and geosynthetic products. As the demand for mats and blankets grew, several different
products were developed utilizing varying compositions and structures. Most of these products work
in conjunction with vegetation to form a biocomposite solution to erosion control problems. The mat
and blanket industry is unique in that it requires blending the professional disiplines of engineering
(mat and blanket products, channel hydraulics, etc.), agronomics, and landscaping (i.e. vegetation).
The wide variety of product types together with the blending of professional diciplines has led this
segment of the industry to "self-regulate" it's activities to improve the use of rolled erosion control
products. -NTPEP-
Chair: Peter Kemp, Wisconsin DOT
Vice Chair: Steve Hall, Tennessee DOT
EROSION CONTROL PRODUCTS PROJECT PANEL
A BRIEF HISTORY OF THIS PROGRAM
PROJECT WORK PLAN
BENCH-SCALE TEST METHODS
SUBMIT A PRODUCT (2003 CYCLE)
INDUSTRY RESOURCES
EROSION CONTROL PRODUCTS PROJECT PANEL -- The NTPEP Project Panel is the
working group charged with developing and maintaining the Project Work Plan, for testing of a
particular product, material or device. The Project Panel convenes at least annually, in conjunction
with the NTPEP Annual Meeting. Project Panel membership may range from six to ten AASHTO
members, and up to two Industry members assigned by the NTPEP Chairman.
NAME
ORGANIZATION
TELEPHONE
Peter Kemp
(Chairman)
Wisconsin DOT
(608) 246-7953
Steve Hall
(Vice Chairman)
Tennessee DOT
(615) 350-4167
Tony Johnson
(Industry Member)
American Excelsior Company
(715) 234-6861
Tim Lancaster
(Industry Member)
North American Green, Inc.
(812) 867-6632
1
2
3
4
5
6
A BRIEF HISTORY -- In 1998, the NTPEP Oversight Committee determined that NTPEP should
consider conducting nationally coordinated evaluaution on "erosion control products." Their initial
discussion revolved around the different types of erosion control products. It was decided that "Rolled
Erosion Control Products (RECP)" should be evaluated first, since they are widely used by state and
local DOTs.
After considerable debate the NTPEP Oversight Committee decided to consider adopting large-scale
test results, similar to those produced by the Texas Transportation Institute (TTI) erosion control lab.
Around the same time, the NTPEP Oversight Committee became aware of industry standards
development vis-a-vis the Erosion Control Technology Council (ECTC). At the time, so-called "benchscale performance index tests" were being developed. As the bench-scale guidelines were gaining
credibility within the industry, AASHTO/NTPEP monitored the activity in hope that it would serve their
program for cost-effective prequalification testing.
In early 2002, a dialogue sparked between the NTPEP Oversight Committee's Project Panel on rolled
erosion control products and members of the Erosion Control Technology Council (ECTC). From that
synergy, at the NTPEP2002 Annual (National) Meeting, AASHTO and ECTC signed a cooperative
agreement to foster government and industry dialogue.
With encouragement from Industry, the NTPEP Oversight Committee pursued research funding for a
study on "Correlation Between Large-Scale and Bench-scale Testing of RECPs." The NCHRP 20-7
Task Force commissioned the study in April 2001. This research study begins with launching of the
RECP program, whereby initally participating manufacturers are included in the NCHRP correlation
research study.
Traditionally, AASHTO contracts with State DOTs (AASHTO Members) to conduct lab and field
evaluation on behalf of the assocation. Because the RECP Work Plan calls for recently developed
test methods, there are no state DOT labs conducting such tests. Generally, State DOTs do not have
the luxury of conducting testing at the scale conducted under auspices of NTPEP; for this reason,
AASHTO/NTPEP has contracted with a private testing firm, TRI/Environmental, Inc. (Austin, Texas)
to conduct testing on behalf of the association. As the program grows and demand warrants,
additional testing facilities will be considered by AASHTO/NTPEP. -NTPEP-
PROJECT WORK PLAN -- NTPEP tests products according to a Project Work Plan, which
describes the laboratory and/or field test protocols used to conduct the evaluation. The Project Work
Plan is a consensus-based document, and includes peer review and input from industry experts.
Each Project Work Plan is adopted after receiving at least two-thirds affirmative support from 52
AASHTO member states. The Project Work Plan is the basis for host states to conduct their testing
and evaluation. When implemented by state DOTs, their own state standard specifications may
supersede the NTPEP Project Work Plan. Industry is advised to be aware of state-level requirements,
which may supersede basic NTPEP testing.
PROJECT WORK PLAN
Adobe PDF
Project Work Plan for Laboratory Evaluation of
Rolled Erosion Control Products (RECP)
[8 pages, 29 KB]
BENCH-SCALE TEST METHODS -- The NTPEP program refers to so-called "bench-scale" test
methods as developed by the Erosion Control Technology Council (ECTC). These test methods
assess index properties for RECPs. The NTPEP Project Panel on RECP decided to adopt benchscale testing for purposes of product prequalification. The alternative approach was to test against
"large-scale testing", which can be quite costly. Because bench-scale testing is new for RECPs, the
NTPEP Oversight Committee commissioned an NCHRP (National Cooperative Highway Research
Program) 20-7 project to "correlate between bench-scale and large scale testing." That project is now
underway.
TEST METHOD
Adobe PDF
ECTC Test Method 2 (Draft)
"Standard Test Method for
DETERMINATION OF ROLLED EROSION CONTROL
PRODUCT (RECP) PERFORMANCE IN PROTECTING SOIL
FROM RAINSPLASH"
ECTC Test Method 3 (Draft)
"Standard Test Method for DETERMINATION OF ROLLED
EROSION CONTROL PRODUCT (RECP) PERFORMANCE
UNDER FLOW INDUCED SHEAR STRESS"
ECTC Test Method 4 (Draft)
"Standard Test Method for DETERMINATION OF ROLLED
EROSION CONTROL PRODUCT (RECP) PERFORMANCE
IN ENCOURAGING SEED GERMINATION
AND PLANT GROWTH"
Memorandum on
"A Standard Vegetated Condition"
SUBMIT A PRODUCT -- NTPEP has introduced partial electronic application for its Rolled Erosion
Control Products (RECP) program. NTPEP will accept applications on a rolling basis with preestablished deadlines for submitting to a particular cycle of testing. These deadlines are: MARCH
15th, JULY 15th, OCTOBER 15th and DECEMBER 15th.
.
.
.
[OPTION 1] -- Electronic Application with PDF e-Forms,OPTION 1 requires the freely available
Adobe Acrobat Reader. (To save completed e-Forms to your hard drive, purchase "Acrobat Approval"
from Adobe.)
DOCUMENT
Invitation to Participate in NTPEP-Coordinated Evaluation
on RECP
(1 page)
"Sample Requirements, Technical Approach
and Fee Schedule"
(7 pages, 55 KB)
"PRODUCT EVALUATION FORM (PEF)"
(1 page, 490 KB)
"Fee Calculation Schedule"
(1 page, 28 KB)
.
.
.
.
[OPTION 2] -- Fax-on-Demand Application,
. . . . Request
Application by e-mail (provide your name, company and fax number)
.
.
.
INDUSTRY RESOURCES
Erosion Control Technology Council (ECTC)
U.S. Dept. of Energy, NEPA Policy and Compliance
FHWA, Office of Bridge Hydraulics
FHWA, Office of Research and Technology
WisDOT, Erosion Control Product PAL
. . . . <SUBMIT A RESOURCE LINK>
Copyright © 2000 AASHTO. All rights reserved.
Geojute - JUTE
FOR
THE
FUTURE
Jute- one of the oldest industries in India, has traditionally been used for packaging.
However its versatility is only coming to light now as the world looks on for natural
options to save the environment. The time has come for this natural fibre to take
over with the ideal solutions for the modern world. Be it in conserving the soil and the
environment or in applications like civil engineering which are essential for the
progress
of
civilization.
Jute Geotextiles comes in two varities - WOVEN & NON-WOVEN
The distinguishing features that make it more eco-friendly are
For Free Listing up of your
Company mail us
Submit your query on Indian
Jute Industry, in general
Click and get the list of
manufactures of JGT
cost of JGT
- High moisture absorption capacity
- Flexibility
- Drainage properties
GeoJute
Finds
Applications in -
- Erosion Control
- Separation, filtration & drainage in civil engineering works
- Agricultural use
ADVANTAGES:
- Abundant availability
- Superior drapability
- Greater moisture retention capacity
- Lower costs compared to synthetic geotextiles
- Ease of installation
- Bio-degradable properties
J U T E
G E O T E X T I L E S
Geotextiles have seen unrivalled growth with a forecast by the United Nations International Trade Centre
(UNITC) of 1,400 million m2 produced by the new millenium. Europe and North American markets each
account for 40% with the remaining 20% attributed to Japan, Asia and Australasia. The main applications are
separators in earth works, drainage and linings as well as controlling soil erosion and establishing plant
growth.
As jute accounts for such a small proportion of geotextile use in the West there is enormous scope for
increased usage. Most land managers in Europe are generally unaware of the relevance of jute products, as
they consider textiles as the main output of the industry. Jute accounts for less than 1% of total geotextile
use, despite the technical advantages and low cost of jute geotextiles, which has been demonstrated by
research and the results of full-scale use. A promotion programme which aims to provide product information
in readily useable form has been initiated by UNITC, UNDP and JMDC.
Conservation land managers, landowners and landscape architects who use jute in environment projects will
see immediate improvements in the rate and quality of vegetation growth, as well as greatly reduced material
costs.
Two seminars in London and Geneva last year brought together key jute producers with invited researchers,
environmental consultants, suppliers, contractors and specifying authorities. Specifications were agreed which
jute geotextiles would need to meet to satisfy environmental and geotechnical engineers. The obvious uses in
erosion control were generally known, but it was interesting to note that composite products involving jute in
combination with synthetics, or jute together with coir, can offer optimum solutions in other areas. Some
applications are clearly suited to jute, but the material characteristics need more elaboration. Other
applications are more easily satisfied by the other types of geotextiles.
A P P L I C A T I O N................................................................................................................................................
Jane Rickson of Silsoe College identified three current main applications for jute:



Erosion control and vegetation establishment
Agroplant mulching
Rural road pavement construction
The salient properties which determine the effectiveness of ageotextile are percentage cover, water holding
capacity, the thickness and roughness of fibres and yarns, their orientation across the slope and installation
procedures which do not disturb the site. Testing over 12 years at Silsoe has proved the technical excellence of
jute compared with other natural and synthetic geotextiles under a range of environmental conditions, showing
that vegetation establishment is highly effective when jute is used.
A newly developed wick drain, formed from a jute sleeve packed with coir, showed how combinations of
geotextile types provide benefits greater than the sum of each. Professor Bob Sarsby of Bolton Institute
reported on full-scale trials of soil walls incorporating jute rope reinforcement. This work graphically
demonstrated the strength of jute in supporting walls of 4m or more. He went on to describe the use jute in
road construction especially over areas of poor ground. Not enough attention has yet been paid to this
potentially extensive application.
The micro-climate surrounding jute geotextiles has been explored by Yves Henri Faure of Grenoble University
who has tested the efficiency of jute sheets in preventing loss of soil in shallow and steep slopes. Earth works
were built on a test-bed capable of being rotated to various inclinations and subjected to simulated rainfall,
varying from light to heavy tropical downpours. The amount of soil lost to erosion was measured. The faces
were then protected by various geotextiles and the soil erosion again measured. The tests simulated wash out
of vegetated soil slopes and provided data of use in landscaping projects. Over the whole range of rainfall
intensities and slope angles jute geotextiles outshone the other materials. A jute of approximately 500g per m 2
appeared to be cost effective.
Using jute to protect large areas from erosion, including high-altitude ski-slopes with significant precipitation,
has been trialed by Francoise Dinger of CEMAGREF. The ability of jute to absorb five times its own weight of
water ( 3kg per m2 of slope ) was demonstrated. The retained water firstly attenuates the run-off into the
drainage system and is then released gradually to soak into the adjacent soil to nourish the vegetation from
severe frosts, so aiding growth.
Mike Hyder of Hy-Tex Ltd. commented that prevention of soil erosion was better and more cost effective than
remedial works. The most vulnerable sites were over steepened slopes, exposed highly erodible sub-soil, and
disturbed or badly compacted ground.
Consequences of soil erosion were: poor growing conditions, additional costs for remedial works, blocked
drains and flooding, pollution of waterways and increased maintenance. Many applications of jute made by his
company were illustrated by ‘before and after’ photographs showing the dramatic improvement in vegetation
growth and erosion control.
Barbara Lois of SIRAS Company described the extensive environmental works undertaken in France using jute
geotextiles, including rehabilitating mine dumps, restoring the Rhone river banks and the vegetating high
altitude steep slopes at the Winter Olympic ski jump in Savoie. Landscaping of slopes alongside the TGV rail
line and along highway cuttings and embankments showed the effectiveness of the geotextiles.
Dr. Finn Terkelsen from Denmark felt that the partners in this field are playing a waiting game. The jute mills
are waiting for the engineers to tell them what to do, whilst the engineers are waiting for the jute mills to
show them what is available. Much research has been carried out by several institutes in jute producing
countries as well as in Europe. Interesting results were seen but wider use did not materialise. It will be
important to address this issue and to use past experiences as stepping stone for future work. There is
currently a very wide gap. Erosion control, foundations, sound barriers, filters, and reinforcement and drainage
were suggested as the most appropriate target uses of jute geotextiles.
C O S T...............................................................................................................................................................
Whilst the cost of geotextiles (selling in Europe for £ 0.40 to £ 0.80 per m 2 ) is lower than synthetic geotextiles
( £ 1.10 to £ 1.35 per m2 approx) and other natural fibre geotextiles (£ 0.75 to £ 2.00 per m2) their usage is
very low. S.K.Bhattacharya of the Indian Jute Mills Association stressed jute was competitive on price, and
other delegates commented that technical characteristics were also superior to other materials in particular
applications.
Jute degrades in over 2 to 4 years, but this is usually a sufficiently long period for vegetation growth to
become established, and trials have shown that degraded by-products are beneficial plants. Work is
progressing to produce treated jute which has a longer life before degradation.
Tentative Cost of Jute Geotextiles
STEEP
S L O P E S.............................................................................................................................................
Steep slopes present particular erosion control problems. Eight soil erosion plots were established on a South
facing slope in a trial carried out by Dr.David Mitchell of Wolverhampton University Experimental Station at
Hilton, Shropshire. Soil erosion of sections protected slope reduced the erosion by 54% whereas the jute
geotextile reduced erosion by 99% compared with the bare slope.
Using jute to resolve the difficulties of vegetating the steep faces of reinforced soil slopes would be helped if
the salient technical aspects were drawn together and published in a form more accessible to users. For
example, jute blended with synthetic fibres has been processed on the existing non-woven production
machinery at British Textile Technology Group (BTTG), ManchesterA range of technical products of widely
varying properties and with weights from 100 to 2000gm per m 2 and with thicknesses up to 60mm can be
produced by this method.
FUTURE
L I N K S..............................................................................................................................................
The two seminars held in London and Geneva in 1997 under auspices of JMDC forged links between all sides of
industry which will be instrumental in helping jute to be accepted and applied more widely in environmental
schemes. The clear need for concise technical information of direct relevance to users was established and the
next phase of the work will address this.
Note: This is reproduction of an article written by Mr. Red Smith, Director, Elwood Consultants Ltd., Albrighton
(UK) which was published in the Autumn’98 issue of ENACT , a UK-based land management magazine. JMDC
utilised the expertise of Mr. Rod Smith for promotion of jute geotextiles in Europe.
(Sourse : INDIAN JUTE newsletter, March 1999)
Landscape Supplies
Erosion Control
Geotextiles
•Polyester Spunbond L/S
Fabric
•Straw & Straw
Coconut Blankets
•Woven Fabrics
•Fiber Blk L/S Fabric Punched •Excelsior Blankets
Woven
•Non-Woven Fabrics
•Steel & Galvanized Edging
•Jute Mesh
•Woven Groundcover
•Edge Pins
•Synthetic Turf Reinforcement •Winter Protection
•Fabric Staples
•Sand Bags - Burlap & Poly
•Seed Germination
•Tree Straps
•Geo-Grids
•Pond Liner Underlay
•Aerators/Coring Tools
•Straw Wattles
•Safety Fence
•Root Feeders & Supplies
•Silt Fence
•Shade Cloth
•Deer Netting
•Oak Stakes
•Sediment Filter Bags
(de-watering bags)
•Windmills: Made in U.S.A.
•Wood Fiber Mulch
•Silt Fence Fabric
•Oak Stakes
•50/50 Blend Mulch
•Silt Fence w/Stakes
•Burlap Rolls & Bags
•Excelsior Logs
•Pocketed Silt Fence
•Woven Ground Cover
•Erosion Netting
•Winter Protection Blankets
•Shade Cloth
•Seed Germination Fabric
What you need to know about Landscape Fabrics.
How does one go about selecting a landscape fabric? This is a question that has confounded
anyone who has found themselves needing a good solution to weed control. About the only
method available currently, is through the comparison of fabric specifications published by each
manufacturer. The problem with this method is that most fabric specifications pertain to
construction applications rather than landscape. Consequently, most of us become boggled down
comparing specifications that have little meaning for our intended purposes. We have tried to
narrow these specifications down to those that are most important to landscape applications. In
an effort to give a basis of comparison to the products we have listed, we have added the
Colorado Department of Transportation specifications to our product comparison sheet.
We feel the selection of a landscape fabric should be based on three areas of consideration.
They are as follows:
1. The fabric should be strong enough to withstand the most vigorous stresses of
application, but no more. Any added strength is offset with a reduction in water and air
flow, and an unnecessary increase in the price of the product.
2. The fabric should have an even, and consistent distribution of fibers, and a small enough
opening size to keep weedy grasses from coming up through the fabric. Contrary to
popular belief, weeds and grasses do not force their way through an obstacle, but rather
grow to the light that comes through the smallest of openings or breaks that may exist.
Weed seeds will also germinate in small accumulations of soil on top of a fabric, and
send tiny root hairs through the smallest of openings to seek water and nutrients from the
soil. This problem is largely avoided with the use of spunbonded fabrics, due to their
almost microscopic opening size.
3. Finally the fabric must be porous enough to allow water and air to pass freely to the soil.
We feel this is one of, if not the most important characteristic of a superior landscape
fabric. If a fabric does not "breathe properly" plants do not get enough oxygen, and soils
become sour and sterile. This was the case when plastic sheeting was being used as a
weed preventative. Another disadvantage of pour permeability is the problem of runoff.
When a fabric does not accept water freely it tends to wash off the fabric taking any
mulch covering, rock or bark, with it. This is a common problem people have mistakenly
blamed on the texture of the fabric surface
Soil Ecology and Restoration Group
Natural materials and container plants or hydroseeding for erosion
control?
Erosion is much less costly to prevent than it is to repair. Even a small erosion gully can
involve many cubic meters of soil that must be collected from the bottom of the slope and
replaced at a cost of hundreds, or more likely, thousands of dollars. Erosion can limit
plant establishment from seeds and destroy irrigation systems and installed landscaping.
Costs are also transferred to others directly through increased flooding, sedimentation and
subsequent flooding damage. Sediment also causes serious damage to aquatic and
riparian ecosystems. In 1998 we reported on research to find materials that can provide
erosion control, enhance native seed germination, and control weeds without harm to
wildlife. These were almost all natural materials without the more common plastic or
plastic mesh reinforced materials which have proved to be harmful in many cases by
trapping wildlife (especially snakes and lizards but also birds) and looking ugly as they
break down.
These tests showed that the combination of natural erosion control materials at Palos
Verde site in March 1999 after a 0.9 inch rain from 2 m x 5 m plots was only 0.5 pounds
per plot for the Curlex, Encs2, Jute, and Cocoa mulch. This was about 1/4 the erosion on
the control plots with plants and 1/6 the plots with coir erosion fences.
To achieve success with biodegradable erosion control methods the materials should be
selected to fit the slope steepness, soil type, weed control method, and anticipated foot
traffic. The most effective materials for erosion control appeared to be the coir and Encs2
mats. Jute netting does well for its relatively low cost, but it is not as stable or easy to
install. The Encs2 coir/straw mat material provided very effective erosion control and
good seed germination and plant survival. These mats are made of completely natural,
biodegradable materials, and can be generally recommended for areas where little or no
foot traffic is expected. They should also be used whenever lizard or snake populations
are present.
The Curlex mats were also effective but include plastic reinforced net. The Curlex netting
had the best plant survival of all treatments and the best germination among the mats.
These results may reflect the greater thickness of the Curlex and better light penetration
than with Encs2. However, the green plastic photodegradable netting that holds the
material together made it difficult to walk on while planting and in other areas created an
unsightly mess. Although problems with bird and reptile entrapment using plastic
materials are not uncommon, none were observed at these sites, perhaps because the top
layer of plastic netting was removed from some test areas (effectiveness or durability was
not noticeably reduced) and reptile populations are low. These Curlex mats could be
reformulated with a jute, hemp, or coir net, but until that is done they should only be used
on sites without lizard and snake populations.
The coir fiber erosion control fences have worked well in some cases, but spacing should
be closer than manufacturers recommend and it must be carefully installed. The net
should be stapled to the stakes used to hold the net in place, back-filled and carefully
compacted. Long stakes should be used on soft sandy slopes. Combining cocoa mulch
with these fences cut erosion in half and some form of mulch should generally be used
with these erosion fences.
Mulch alone was more effective than erosion than erosion control fences at one site. The
cocoa mulch appeared to improve native seed germination and has the advantage of not
having any weed seeds which may survive composting operations. This material was
heavy enough to keep the seeds from blowing away and retained moisture, but readily
allowed the seedlings to grow. The new seedlings were noticeably clustered in patches of
mulch.
Pitting and mulch showed very variable results depending on the soil conditions and
slope. At the Tank 76 south site pitting and mulch controlled erosion better than jute
netting. At the FCTCP site pitting appeared to disrupt the soil and created more erosion
than the control.
Mulch alone or pitting and mulch can work well on shallow slopes or small pockets of
disturbed soil where sheet flow is not expected. Dense planting alone is suitable on some
sites. This might be more effective with grasses than with shrubs. The roots of container
plants also help stabilize slopes.
Straw flake check dams are inexpensive and recommended for areas which are narrow
and may have substantial water flow, such as old dirt roads. These dams are inexpensive
and easy to install. A self-propelled trencher would increase the speed of installation. A
7.5-10 cm wide slot 15-25 cm deep is cut across the slope and then flakes of a straw bale
5-10 cm thick are placed in the trench. The soil is then back-filled and compacted around
the vertical straw fence. Weed free straw or rice straw, which persists longer thanks to
high silica content, is recommended to reduce the risk of introduction of exotic species.
These natural fiber erosion control methods should all be more widely used. These are
more costly than hydroseeding but more effective than conventional hydroseeding
practices. At one Point Loma site an adjacent site was hydroseeded by a different
contractor, this became an eroded, weed infested slope which will require costly repair
work.
Hydroseeding success
In an effort to improve hydroseeding effectiveness we compared several application
methods on an erosive sandy slope. Treatments include: conventional hydroseeding with
fiber, hydroseeding followed with compost, hydroseeding followed with blown straw,
punched straw followed with hydroseed, and a dual application of seeds first, well
churned into the soil, followed by a second fiber application. The goal was to control
erosion, encourage germination of native seeds and improve survival of container plants.
The dual application, seeds first then fiber was most effective. Plant density was double
conventional hydroseeding application and the plant cover was highest. We suspect this
increase results from the churning application of seeds and water to the soil that ensures
good seed/soil contact. It may also benefit from deeper wetting of the soil, giving the
seedlings more moisture to grow. This double application is more expensive, but added
substantial benefits in plant establishment. For less erosive slopes this application
technique should be more cost effective than natural mulches and container planting.
This was followed by hydroseeding followed by compost 10%+ better than conventional
methods, which had the second highest cover. The punched straw followed by
hydroseeding, showed a 25% increase in density but much reduced cover. Hydroseeding
followed by blown straw had reduced density and cover.
For less erosive slopes a hydroseeding application with just seeds churned into the soil in
a first coat, followed by a second layer with fiber appears to be a realistic and cost
effective treatment. Low points should be treated with straw flake, coir, or straw wattles
or check dams. Conventional hydroseeding is rarely effective in dry areas unless the
timing is fortunate enough to catch seasonal rains or if irrigation systems are installed.
.
Jute Geotextiles The Utility Fabric
Vision 2001 |
Eastern Window |
Email | Home
JUTE GEOTEXTILES– THE
UTILITY FABRIC FOR
BIOTECNICAL SOLUTIONS TO
SOIL – RELATED PROBLEMS
By A Correspondent
Geotextiles are textiles applied
on soil for improvement of some of
its technical characteristics.
Geotextiles may be either
synthetic or natural. Synthetic
Geotextiles are made of synthetic
fibres like polypropylene,
Polyethelene and some other
petrochemical derivatives. Natural
Geotextiles, on the other hand,
are made out of natural fibres
like jute, coir, sisal and the
like. Jute Geotextile is thus a
variety of natural geotextiles.
Properly designed jute geotextiles
are supposed to perform the
following functions separately or
in conjunction in the application
areas related to civil
engineering:





Separation
Filtration and drainage
Initial reinforcement
control of detachment
surface soil
Vegetation support In view of
the aforesaid function there
are several areas of
application of jute
geotextile in civil
engineering which have
proved effective after field
trials. These are:
o Surface soil erosion
control
o Bank protection in
rivers and waterways
o Erosion control in
slopes
o Stability of
embankments for
highways, railways and
flood-control.
o Strengthening of a
road structure
o
Consolidation of soft
soil
JUTE GEOTEXTILES FOR
BANK PROTECTION OF
WATERWAYS :
Application Areas
The conventional method of
river bank protection
envisages laying of a
permeable multi-layer
granular overlay on the
eroded surface with armours
on top. The method is not
only expensive and timeconsuming, but also eludes
precise placement as per the
design thickness and
grading. Use of a jute
geotextile filter can
simplify the protective
construction in terms of
ease of installation,
economy and precision.
Technical Functions:
o
o
o
o
Retention of fines
with the tailor-made
porometry (size of
openings) in the jute
geotextile.
Separation of the soil
surface from the
armour-overlay.
Promotion of growth of
vegetation leading to
natural protection.
Prevention of
development of
differential porewater over-pressure
across the jute
geotextile due to its
site-specific
permittivity (across)
and transmittivity
(along plane)
functions.
CONSTRUCTION OF
EMBANKMENT
Application Areas
o
o
o
o
Construction of
railway, road and
flood embankments on
soil of low bearing
capacity.
Slope protection of
high embankments.
Effective drainge
system.
Vertical drains to
drain out water in the
embankment during
construction.
TECHNICAL FUNCTIONS
Jute Geotextile
o
o
o
o
Check subsidence of a
pavement by separating
and preventing
intermixing of the
soft sub-grade and the
harder sub-base.
Arrests migration of
soil particles and
allows water to
permeate across it.
Also acts as a
drainage layer along
its plane. Can be
tailor-made to cater
to the requirements of
porometry,premittivity
and transmittivity.
Enhances CBR-value at
the subgrade lavel.
Enhances strength and
stability of high road
embankment built with
materials of uncertain
behaviour like PFA
(pulverised fly-ash),
when interposed at
appropriate levelsAlso keeps lateral
dispersion, subsidence
and slides (slip
circle failures) under
check.
Provides effective
drainage system when
o
o
used as peripheral
cover in trench
drains, specially in
hilly terrains.
Vertical fibre drains,
helps drain out
entrapped water from
within an embankment.
Useful for both
surface and subsurface drainage.
Slopes of embankments
with problematic soil
may be stabilised by
applying jute
geotextile to help
grow vegetation faster
and anchor soil for a
permanent solution
PROTECTION OF SLOPES
Application Areas
o
o
o
o
Protection of slopes
in road and railway
embankments, bridge
approaches, hills,
terraces in hilly
terrains.
Stabilisation of sanddunes, mine spoils, O
B dumps in open cast
mines, PFA dumps in
thermal power plants,
slag heaps.
Promotion of quick
vegetation in areas
denuded by natural
calamities like
cyclones, earthquakes,
landslides.
Stabilisation of
waste-dumps.
Technical Functions:
o
Jute Geotextile when
used on the exposed
slopes and bare soil,
reduces erodibility
o
o
o
o
o
coefficient of the
soil(and restrains the
progressive detachment
and transport of soil
particles due to the
rain splash and flow
of water along the
slope, reducing soil
loss).
Highly water
absorbent; absorbs
water about 5 times
its weight.
Highly drapable drapability enhances
when wet.
Forms ''mulch'' retains moisture and
builds up a humid
surrounding conducive
to germination of
seeds and growth of
plants. Stimulates
growth of vegetation 100% coverage within 3
months on fertile
topsoil.
Helps in consolidation
of waste and garbage.
Enhances roughness of
the soil surface which
helps in reduction of
velocity of water-flow
over it and helps
entrapment of eroded
soil-particles
erosion protection materials | geomembrane | geosynthetic clay liner |
drainage material | geopipe | gabion
Erosion protection materials is the material that used to control the
erosion (simultaneous removal of particles of soil) by running water,
waves, currents, moving ice or wind.
We have several geosynthetic materials for erosion protection application,
which are:
 Enkamat
 Biodegradable Erosion Protection
 Armater
 Incomat
application
ENKAMAT
A three-dimensional erosion control
matting, made of polyamide
monofilaments welded together where
they cross each other, with an open
space of over 95%.
BIODEGRADABLE EROSION
PROTECTION
Erosion protection material which is
made from biodegradable material like
jute, coconut fibre etc. Fields of
application of Biodegradable Erosion
Protection are erosion control for:
 Embankment
 Landscaping
ARMATER
A honeycomb-type geocomposite, made
by alternate linking of strips of polyester
non-woven by stitching it together.
 Nature friendly protection against
erosion by wind and surface runoff water
 Fixation of 10 cm of fertile soil on
sterile underground to allow
establishment of vegetation
INCOMAT
A construction system for earthwork
engineering, foundation engineering and
hydraulic engineering which consist of
two very strong synthetic fabric plies
specially linked with each other as a
formwork which is filled with high
strength concrete.
Incomat offers the technically solution
and economic alternative to
conventional slope and bed protection
systems using geotextiles and rock fill,
and provides specific erosion protection
for unprofiled natural beds and slopes,
even in areas below water where access
is difficult.
Incomat is used to protect slopes and
beds of canals, rivers and other flowing
bodies of water and on sea coasts for
dikes, embankments and jetties, for
hurricane tide barriers, outlet structures,
manmade islands, pipelines and for
inshore and offshore structures in
general.
woven geotextile | nonwoven geotextile | vertical wick drain | geogrid |
erosion protection materials | geomembrane | geosynthetic clay liner |
drainage material | geopipe | gabion
2001 Technical Program
Topic
Site Visit: Southern Expessway
Stage 2 will extend the Southern Expressway by 12 kms
from Reynella at the northern end, to Main South Roan at
the southern end. Completion, at a cost of $76.5 million,
will allow traffic to bypass 15 sets of traffic lights thereby
saving 10 minutes in travel time. The
Expressway includes 2 lanes, a stopping lane and
connections at Sherriffs, Beach and Main South Roads.
Nine significant road bridges, 5 pedestrian/cyclist bridges
and culverts have been built including the 140m long
bridge over Grant Road Creek and the 50m long bridge
over Sherriffs Road. Construction has involved moving 2
million tonnes of earth, installing 10km of stormwater
pipework, developing stormwater ponds and wetlands and
planting 60,000 trees. It will deliver significant economic
benefits to Adelaide and the southern suburbs including
reduced travel times, reduced congestion, reduced
pollution, reduced operating costs and reduced crash costs.
All this makes the Southern Expressway a very significant
project for Adelaide and a fitting one for this year's AGS
site visit.
Speaker(s)
Stephen Becket,
Maunsell McIntyre
Roger Grounds,
Tim Sullivan
Report)
Pells, Sullivan, Meynick
The Thredbo Landslide, although very small by most
standards, was Australia's most significant landslide in
terms of societal impact with the highest death toll (18
people) and probably the highest indirect economic loss.
The official report on the tragedy by the Coroner found:
"The Alpine Way fill embankment which ran……….above
Thredbo Village was in a marginally stable state and
extremely vulnerable to collapse if saturated by water."
"The propensity of the Alpine Way to landsliding which
could lead to destruction of lodges and serious injury to
persons within them was known."
But despite this, a water main was approved and placed in
the Alpine Way embankment. The main was constructed of
materials that could not withstand movements. This
situation occurred above a site where:
"The stability and geotechnical problems……….were
recognised and understood before any development of the
Village in this area."
There are many lessons to be learned from the
investigation and understanding of the landslide, both in
February
19
Coffey Geosciences
Thredbo Landslide (Download NSW Coroner's
(Video Available)
Date
March 19
technical terms and for the geotechnical profession as a
whole. In particular, the Coroner
also found that:
"The geotechnical community needs to evaluate the way it
conducts its investigations to ensure the investigations be
undertaken having regard to the potential effect of
instability on human life and the risk of loss of life or
injury."
The presentation focussed on the landslide mechanism, the
strength parameters, the method of analysis, causes and
contributing factors, historical perspective, risk and lessons
for the profession.
Linear Landfill or Driver's Dream - Can We
Successfully Use Alternative Aggregates to
Make Pavements? (Video Available)
Dr. Andrew Dawson
University of
Nottingham, UK
March 26
Dr. Fred Baynes
Baynes Geologic, Perth
May 8
There is an increasing environmental drive to reduce
quarrying of geological stone and, at the same time, to
reduce the volume of waste and by-product materials going
to dump or low-value uses. Road construction consumes
vast quantities of bulk material so seems a natural place to
use alternative materials such as ash, slag, foundry sand,
glass cullet, crumbed tyre rubber, etc. Engineers are then
tasked with the job of making these materials work. They
must deliver a serviceable pavement to the normal
expectations of the user and, at the same time, must not
generate any pollution of the environment into which they
have been placed. Andrew Dawson summarised several
studies, which have looked at the means of economically
improving residues so as to make them mechanically
suitable as lower pavement layers and also reported on the
leaching behaviour of these materials in simulated roadenvironment conditions. Particular issues addressed were
the means of assessment, mix design, quality control, timerelated behaviour and water quality.
The Lost Art of Engineering Geological
Mapping
(Video Available)
Engineering geological and geomorphological mapping is
an essential part of the investigation, design, and
construction of most projects, yet this crucial activity is
often carried out in a haphazard manner or even omitted.
Sometimes this is because project managers are simply
unaware of the value that mapping contributes. Some
examples of the potential consequences of not mapping
were described (anonymously!) and a series of case
histories of projects in different geological environments
were then presented to illustrate typical mapping studies,
the underlying thought processes, the production methods,
and the overall usefulness of these maps.
Underground Design in the SA Opal Fields
(Video Available)
Dr. Tony Meyers
University of SA and
RockTest
June 18
Craig Covil
Arup, Sydney
July 9
Since their discovery in 1915, the opal fields around
Coober Pedy, Lambina, Mintabbie and Andamooka have
been the largest producer of precious opal in the world. It
is estimated that, up to the late 80s, they produced in
excess of $25 million of rough opal per year, which
represented about 80% of Australian and 75% of the
world's opal production. However, in recent years the
miners have been experiencing a considerable downturn in
production due to a lack of significant new discoveries
while at the same time having to endure economic
problems attributed to depressed prices for rough opal and
increases in diesel, explosives and general living costs.
This pressure has forced some miners to go "pillar
bashing" in which they extract the rock in their pillars,
which represent their primary support. By doing so they
have created unsafe spans, caused large amounts of rock to
become unstable which has resulted in rockfalls that have
killed many of them. As a result of these and similar
developments, there has been a push from the local Miners
Associations, Mines Rescue, the local Councils and the
Mining and Quarrying Occupational Health and Safety
Committee (M&QOHSC), for all underground
development in the opal fields, including that done in
dugouts, to be done only after some basic design principles
have been considered; principles which until recently have
often been unknown or ignored.
This talk will provide an overview of a study involving Dr
Meyers in conjunction with M&QOHSC which has, for the
first time, sought to determine the engineering
characteristics of the rocks in the opalised zone and the
behaviour of these rocks once excavated. The talk will
provide a general look at the overall geology of the region
and the lure of the opal, it will provide an overview of the
innovative mining methods used in the fields and it will
discuss the results from the study. It will also discuss the
novel manner in which the results are being presented to
the miners, many of whom come from non-English
speaking backgrounds and diverse cultures. (15 attendees)
Chek Lap Kok Airport Hong Kong
(Video Available)
In 1990 the Hong Kong Government launched the Airport
Core Programme to provide a new international airport
together with nine associated projects at a total cost of over
twenty billion US dollars, making it one of the world's
largest infrastructure developments. The completion of the
New Hong Kong International Airport in only seven years
and within budget is testament to Hong Kong's remarkable
record of delivering major construction projects.
The site preparation was the foundation to the airport
project, supplying 1248 hectares of land, three-quarters of
which were reclaimed from the sea in just two and a half
years by a unique combination of dredging, mining and
seawall operations. Forty thousand tonnes of explosives
were used to reduce Chek Lap Kok Island from a height of
122 metres to only 6 metres above sea level, extensive
reclamation work required the largest fleet of dredgers ever
assembled. Site investigation and instrumentation was
extensive and settlement was predicted and incorporated
into the design and construction of the various facilities
using an observational approach.
The presentation covered the site preparation, dredging
works, seawall construction, land reclamation, blasting,
bulk earthworks, geology, site investigation, settlement,
instrumentation, ground treatment, construction aspects of
the civil and structural elements of the airport facilities up
until opening day operations.
The Use of the Dilatometer Test (DMT) in Soil Prof. Gianfranco Totani August 6
L'Aquila University in
Investigation and in Geotechnical Design
Italy
The seminar gave a general overview of the DMT and its
design applications; indications and guidelines for the
proper execution of the DMT; and highlighted a number of
significant recent findings and practical developments.
Attention was mostly focused on the application of the
DMT to the following engineering problems: settlements
prediction; determination of flow parameters ( in particular
the coefficient of consolidation); study of landslides;
analysis of laterally loaded piles; evaluation of
liquefiability of sands; and densification control.
Latest Advances in Geofabrics and Geogrids
Geotextiles have been used in Australia for over 30 years
for a range of applications including subsurface drainage,
roadway separation, roadway stabilization, permanent
erosion control, temporary silt fences and under paving.
Key developments in the local industry occurred in the
1980s when Geofabrics Australasia set up a facility in
Albury to produce the non-woven Bidim fabric. Since then
Geofabrics have established, produced and promoted the
use of Megaflo drainage panel, Bentofix geosynthetic clay
liners and a range of erosion control products, all made in
Australia. Tensar geogrids, manufactured in England, are
distributed by the regional offices of Geofabrics and are
incorporated in subgrade stabilisation and reinforced earth
retaining wall structures. This talk presented these products
Rod Fyfe
Geofabrics Australasia
September
17
and discussed their application in local South Australian
projects.
Young Geotechnical Engineers Night and
Annual General Meeting
Various Young
Geotechnical Engineers
and Students
October 8
A number of young geotechnical engineering graduates
and students will individually give a 10 minute
presentation on a range of interesting projects. Members
of the Committee will adjudicate and the winner will be
presented with a certificate and a $250 cash prize.
November
19
Visitors Night
Each year, the last meeting is devoted to a social event
where members and others are encouraged to bring along
their wives and partners for a fine and inexpensive
meal. The evening includes a non-technical presentation.
For further information contact:
Dr Mark Jaksa
Page: 2001.HTM
Section 4169. Erosion Control Materials.
4169.01 DESCRIPTION.
Erosion control materials shall include all materials required to be furnished and described in this
section.
4169.02 SEEDS.
All seeds shall be furnished and approved for use according to requirements of this section,
including specified purity and germination, as shown in Table 4169.02. All seeds, including grass,
legume, forbes, and cereal crop seeds, shall be furnished from an established seed dealer or
certified seed grower and shall meet requirements of the Iowa Department of Agriculture
regulations (Iowa Seed Law) and shall be labeled accordingly. The test date to determine the
percentage of germination requirement shall have been completed within a 9 month period
exclusive of the calendar month in which the test was completed. The seed analysis on the label
shall be mechanically printed.
Approval of all seed for use will be based on the accumulative total of Pure Live Seed (PLS)
specified for each phase of the work, so that the PLS is not less than the accumulative total of the
PLS specified. PLS is obtained by multiplying purity times germination.
If the purity and/or germination of native grasses exceeds the minimum required, the application
rate may be adjusted, based on PLS.
If the seed does not comply with minimum requirements for purity and germination and such seed
cannot be obtained, the Engineer may approve use of the seed on a basis of PLS or may
authorize a suitable substitution for the seed specified.
TABLE 4169.02
SEEDS
COMMON NAMES, SCIENTIFIC NAMES, PURITY, & GERMINATION
Common Name
Scientific Name
Pur. (%) Germ. (%)
DOMESTIC GRASSES:
Bluegrass, Kentucky
Bluegrass, Ky. RAM-1
Bluegrass, Ky. PARK
Brome, smooth-LINCOLN
Fescue, tall, FAWN
Fescue, tall, KY. 31
Fescue, chewings, red
Fescue, creeping, red
Fescue, red-PENNLAWN
Fescue, Tall, Olympic (Fineleaf)
Fescue, Tall, Rebel (Fineleaf)
Fescue, Sheeps
Orchardgrass
Red top
Reed Canarygrass
Wildrye, Canada
Wildrye, Russian
Ryegrass, Perennial
Timothy
Poa pratensis
Poa pratensis-RAM-1
Poa pratensis-PARK
Bromus inermis
Festuca arundinacea-FAWN
Festuca arundinacea-KY. 31
Festuca rubra var. commutata
Festuca rubra
Festuca rubra PENNLAWN
Festuca arundinacea-Olympic
Festuca arundinacea
Festuca ovina
Dactylis glomerata
Agrostis alba
Phalaris arundinacea
Elymus canadensis
Elymus junceus
Lolium perenne
Phleum pratense
85
95
95
90
98
98
98
98
98
98
98
98
90
92
98
95
95
95
99
80
85
85
85
85
85
90
85
85
85
85
85
90
85
70
85
85
90
85
Medicago sativa
Medicoa spp.
Lotus corniculatus
Coronilla varia
Vicia villosa
Lespedeza stipulacea
Trifolium pratense
Trifolium hybridum
Trifolium repens
99
99
98
98
96
98
99
99
98
90*
90*
85*
70*
85*
80*
90*
90*
90*
Avena sativa
Secale cereale
Sorghum vulgare var. sudanese
97
97
98
90
90
85
LEGUMES:
Alfalfa, RANGER/VERNAL
Alfalfa, Travois
Birdsfoot Trefoil EMPIRE
Crownvetch, Emerald
Hairy Vetch
Lespedeza, Korean
Red Clover, medium
Alsike Clover
White Clover
NURSE CROP OR STABILIZING CROP:
Oats
Rye
Sudangrass, PIPER
*Includes hard seed.
SEEDS
COMMON NAMES, SCIENTIFIC NAMES, and PLS
Common Names
Scientific Names
PLS
(%)
NATIVE GRASSES:
Big Bluestem - Kaw, Pawnee, Roundtree or Champ
Little Bluestem - Blaze, Aldous or Camper
Switchgrass - Blackwell, Pathfinder, Cave-in-Rock
or Nebr. 28
Indiangrass - Neb. 54, Oto, Holt or Rumsey
Sideoats Grama - Trailway, Butte or El Reno
Western Wheatgrass - Barton or Common
Buffalograss - Texoka or Sharp's Improved
Sand Bluestem - Champ or Goldstrike
Blue Grama
Intermediate Wheatgrass
Slender Wheatgrass
Prairie Dropseed
Sand Dropseed
Sand Lovegrass
Weeping Lovegrass
Hairy Wood Chess
Blue-joint grass
Bottlebrush sedge
Tussock sedge
Fox sedge
Virginia wild-rye
Reed manna grass
Fowl manna grass
Common rush
Rice Cut Grass
Rye grass, annual
Fowl bluegrass
Green bulrush
Wool grass
Soft-stem bulrush
Indian grass
Spike Rush
Andropogon gerardii
Andropogon scoparius
Panicum virgatum
Sorghastrum nutans
Bouteloua curtipendula
Agropyron smithii
Buchloe dactyloides
Andropogon gerardii, var.
paucipilus
Bouteloua gracilis
Agropyron intermedium
Agropyron trachycaulum, var.
unilaterale
Sporobolus heterolepis
Sporobolus cryptandrus
Eragrostis trichodes
Eragrostis curvula
Bromus purgans
Calamagrostis canadensis
Carex comosa
Carex stricta
Carex vulpinoidea
Elymus virginicus
Glyceria grandis
Glyceria striata
Juncus effusus
Leesia oryzoides
Lolium italicum
Poa palustris
Scirpus atrovirens
Scirpus cyperinus
Scirpus vallidus
Sorghastrum nutans
Eleocharis palustris
30
30
63
30
30
56
60
30
30
70
70
65
65
65
65
60
47
62
78
64
60
50
72
80
62
89
72
45
78
78
60
71
FORBES:
Canada anemone
Marsh milkweed
New England aster
Swamp aster
Showy tic-trefoil
Joe-pye weed
Boneset
Ox Eye sunflower
Blue-flag iris
Meadow blazingstar
Tall blazingstar
Great blue lobelia
Reed manna grass
Fowl manna grass
Common Rush
Rice Cut Grass
Anemone canadensis
Asclepias incarnata
Aster novae-angliae
Aster puniceus
Desmodium canadense
Eupatorium maculatum
Eupatorium perfoliatum
Heliopsis helianthoides
Iris virginica-shrevii
Liatris ligulistylis
Liatris pycnostachya
Lobelia siphilitica
Glyceria grandis
Glyceria striata
Juncus effusus
Leesia oryzoides
72
25
25
25
25
66
41
38
19
24
24
13
50
72
80
62
The accumulative total of Pure Live Seed (PLS) is the product obtained by multiplying the pounds
(kilograms) of each seed by the purity and germination percentages expressed as decimals.
Calculations will be based on test results of samples taken by the Contracting Authority. If the
seeds were not sampled or if these test results are not available, the PLS will be calculated from
information shown on the label.
4169.03 FERTILIZER.
Fertilizer shall be of the grade, type, and form specified and shall comply with rules of the Iowa
Department of Agriculture and the following requirements:
The grade of fertilizer will be identified according to the percent nitrogen (N), percent
available phosphoric acid, (P2O5), and percent water soluble potassium, (K2O), in that
order, and approval will be based on that identification.
All fertilizer shall be furnished from an established fertilizer dealer and guaranteed
analysis shall be provided through mechanically printed commercial fertilizer bags or a
manufacturer's (not a distributor's) bill of lading.
Inspection and acceptance of fertilizer will be in accordance with Materials I.M. 469.03.
Fertilizer shall be of a type that can be uniformly distributed by the application equipment.
When applied by hydraulic methods, fertilizer may be chemically combined or may be
furnished as separate ingredients. When applied by other means, each unit of fertilizer
shall be chemically combined, and the manufacturer's guarantee shall indicate
compliance with this requirement.
Fertilizer may be furnished in a dry or liquid form.
The Contractor shall furnish a list of the number of containers and a corresponding scale
ticket from an approved scale for the fertilizer to be used in the work.
Official samples taken by the Contracting Authority may be tested. A tolerance of minus
1.0 percentage point from the guaranteed analysis for each nutrient will be considered
substantial compliance.
Ground limestone shall be of the type known as No. 1 fine (70% passing No. 200 (75 µm)
sieve) with an analysis of elemental calcium of not less than 37% nor more than 40%.
4169.04 INOCULANT FOR LEGUMES.
An inoculant is a culture of bacteria specifically formulated for legume seeds (alfalfa, clovers,
lespedeza, birdsfoot trefoil, hairy vetch, and crownvetch). The manufacturer's container shall
indicate the specific legume seed to be inoculated and the expiration date. All inoculant shall
meet requirements of the Iowa Seed Law. Safety precautions specified on the product label shall
be followed.
4169.05 RESERVED.
4169.06 STICKING AGENT.
A sticking agent shall be a commercial material recommended by the manufacturer to improve
adhesion of inoculant to the seed. For quantities less than 50 pounds (25 kg), the sticking agent
need not be a commercial agent, but shall be approved by the Engineer and shall be applied
separately prior to application of inoculant. Safety precautions specified on the product label shall
be followed. A sticking agent is not required if a liquid formulation of inoculant is used.
4169.07 SOD.
Sod shall consist of approximately 1 inch (25 mm) of well established turf consisting of live
Kentucky bluegrass, unless otherwise specified. Sod shall be free from roots of trees or brush,
stones, and other objectionable materials. Sod shall be free from all noxious weeds and
reasonably free of all other weeds.
Sod shall be cut in strips of uniform width and thickness with ends square. The Engineer may
order the thickness adjusted to meet the sod conditions. Sod shall be cut to the length specified
for the use intended. If not specified, the minimum length shall be 3 feet (1 m). All sod areas shall
be mowed to a height of approximately 1 1/2 inches (40 mm) to 2 inches (50 mm) prior to cutting.
Sod shall have been regularly maintained prior to cutting. The Contractor shall be responsible for
the application of pre-emergence weed control chemicals and weed control chemicals for
broadleaf weeds.
Within 1 hour after being cut, sod shall be rolled or stacked. Other methods of handling sod may
be approved by the Engineer. Precautions shall be taken to prevent drying or heating. Sod
damaged by heat or dry conditions, or sod cut more than 18 hours before being incorporated into
the work, shall not be used.
Sod will be subject to inspection by the Engineer at the job site, and approval of the work
constitutes approval of the material.
4169.08 MULCH.
Material used as mulch may consist of threshed or unthreshed hay, threshed or unthreshed
prairie hay, threshed cereal straw, wood excelsior, wood cellulose, or other material, as specified.
All material used as mulch shall be free from noxious weeds.
The Contractor shall furnish a list of the number of bales and corresponding ticket from an
approved scale for the mulch material to be used on the project.
Wood excelsior shall be composed of wood fibers, a minimum of 8 inches (200 mm) long, based
on an average of 100 fibers, and approximately 0.024 inch (600 µm) thick and 0.031 inch (800
µm) wide. The fibers shall be cut from green wood and shall be reasonably free of seeds or other
viable plant material. Wood excelsior shall be baled and the weight (mass) determined. The
weight (mass) of the material shall be furnished by the manufacturer and shall be used for
determining the rate of application.
4169.09 STAKES FOR HOLDING SOD.
Stakes for holding sod shall be either wood or metal, except that wood stakes shall be used in
sandy soils or when required by the Engineer.
Wood stakes for holding sod shall be 1 inch (25 mm) to 1 1/2 inches (40 mm) in width, 1/4 inch (6
mm) to 1/2 inch (13 mm) in thickness, and 12 inches (300 mm) long. Where this length of stake
does not provide firm bearing, the Engineer may require stakes of sufficient length to secure firm
bearing.
Wire stakes shall be in the form of staples made from No. 11 (3.06 mm diameter) wire or heavier
and shall have a minimum 2 inch (50 mm) flat spread on the top of the sod. The legs shall be at
least 6 inches (150 mm) in length. The Engineer may require wire legs longer than 6 inches (150
mm).
4169.10 SPECIAL DITCH CONTROL AND SLOPE PROTECTION.
Jute mesh, plastic netting, wood excelsior mat, and wire staples shall comply with the following:
A. Jute Mesh Over Sod.
Jute mesh over sod shall be a uniform, open, plain weave, of single jute yarn. The yarn
shall be of loosely twisted construction and shall not vary in thickness by more than 50%
its normal diameter. Jute mesh shall be furnished in rolled strips and shall meet the
following minimum requirements:
Jute mesh shall be nontoxic to the growth of plants and germination of seeds and
shall be identified by tag.
Width - minimum 48 inches ± 1 inch (1.2 m ± 25 mm) from manufacturer's rated
width.
78 warp ends per 4 feet (1.2 m) of width.
45 weft ends per yard (meter).
Weight (mass) to average 1.22 pounds per linear yard (0.6 kg per meter) (based
on 48 inch (1.2 m) width) with a minus tolerance of 5%.
All material must be new and unused.
At the Contractor's option, plastic netting (polypropylene) may be substituted for jute
mesh. It shall meet the following requirements:
Color - black or green, with UV additives
Mesh size - approximately 0.6" x 0.7" (15 mm x 18 mm)
Weight (Mass) - approximately 9 pounds per 1,000 square feet (44 g/m2)
Width - 48 inches (1.2 m) minimum
B. Wire Staples.
Wire staples for holding special ditch control wood excelsior mat and special ditch control
jute mesh over sod shall meet the following requirements:




Wire staples shall be U-shaped.
Length of each leg shall be 6 inches (150 mm) minimum.
Wire diameter shall be No. 11 (3.06 mm) wire.
Staples shall be of sufficient hardness to facilitate installation without bending. In
sandy soil conditions, wire staples with a minimum length of 12 inches (0.3 m)
will be required when directed by the Engineer.
C. Wood Excelsior Mat.
Wood excelsior mat shall meet the requirements of Materials I.M. 469.10.
Wood excelsior mat shall be a mat of interlocking wood fibers with a plastic netting
applied to both sides for holding the excelsior in place. The mat shall be nontoxic to
growth of plants and germination of seeds. The netting applied to both sides shall have a
mesh size of approximately 5/8 inch by 3/4 inch (16 mm by 19 mm). The mat shall be
furnished in rolls with a minimum length of 180 feet (55 m) and a uniform, minimum width
of 48 inches (1.2 m), within a tolerance of minus 1 inch (25 mm) and plus 3 inches (75
mm). As furnished, the mat shall have a minimum weight (mass) of 0.88 pound per
square yard (480 g/m2). The mat shall be furnished in plastic bags or otherwise protected
to prevent damage from weather or handling.
At the Contractor's option, straw-coconut fiber mat or coconut fiber mat may be
substituted for wood excelsior mat for special ditch control, and straw mat, straw-coconut
fiber mat or coconut fiber mat may be substituted for wood excelsior mat for slope
protection. These mats shall meet the following requirements:
The mat shall be of consistent thickness with the straw, straw-coconut fiber or
coconut fiber evenly distributed over the entire area of the mat. The top side of
the mat shall be covered with a polypropylene netting with a 3/8 inch by 3/8 inch
(9.5 mm by 9.5 mm) mesh attached with cotton thread. The mat shall be
furnished in rolls with a minimum width of 47 inches (1190 mm) and a minimum
length of 80 feet (24 m). As furnished, the mat shall have a minimum weight
(mass) of 0.50 pound per square yard (270 g/m2). The mat shall be furnished in
plastic bags or otherwise protected to prevent damage from weather or handling.
Erosion control materials shall include all materials required to be
furnished and described in this section.
4169.02 SEEDS.
All seeds shall be furnished and approved for use according to
requirements of this section, including specified purity and
germination, as shown in Table 4169.02. All seeds, including grass,
legume, forbes, and cereal crop seeds, shall be furnished from an
established seed dealer or certified seed grower and shall meet
requirements of the Iowa Department of Agriculture regulations (Iowa
Seed Law) and shall be labeled accordingly. The test date to determine
the percentage of germination requirement shall have been completed
within a 9 month period exclusive of the calendar month in which the
test was completed. The seed analysis on the label shall be
mechanically printed.
Approval of all seed for use will be based on the accumulative total of
Pure Live Seed (PLS) specified for each phase of the work, so that the
PLS is not less than the accumulative total of the PLS specified. PLS
is obtained by multiplying purity times germination.
If the purity and/or germination of native grasses exceeds the minimum
required, the application rate may be adjusted, based on PLS.
If the seed does not
germination and such
use of the seed on a
substitution for the
comply with minimum requirements for purity and
seed cannot be obtained, the Engineer may approve
basis of PLS or may authorize a suitable
seed specified.
TABLE 4169.02
SEEDS
COMMON NAMES, SCIENTIFIC NAMES, PURITY, & GERMINATION
Common Name
Scientific Name
Pur.
(%)
Germ.
(%)
85
95
95
90
98
98
98
98
98
98
98
98
90
92
98
95
95
95
99
80
85
85
85
85
85
90
85
85
85
85
85
90
85
70
85
85
90
85
DOMESTIC GRASSES:
Bluegrass, Kentucky
Bluegrass, Ky. RAM-1
Bluegrass, Ky. PARK
Brome, smooth-LINCOLN
Fescue, tall, FAWN
Fescue, tall, KY. 31
Fescue, chewings, red
Fescue, creeping, red
Fescue, red-PENNLAWN
Fescue, Tall, Olympic
(Fineleaf)
Fescue, Tall, Rebel
(Fineleaf)
Fescue, Sheeps
Orchardgrass
Red top
Reed Canarygrass
Wildrye, Canada
Wildrye, Russian
Ryegrass, Perennial
Timothy
Poa pratensis
Poa pratensis-RAM-1
Poa pratensis-PARK
Bromus inermis
Festuca arundinacea-FAWN
Festuca arundinacea-KY.
31
Festuca rubra var.
commutata
Festuca rubra
Festuca rubra PENNLAWN
Festuca arundinaceaOlympic
Festuca arundinacea
Festuca ovina
Dactylis glomerata
Agrostis alba
Phalaris arundinacea
Elymus canadensis
Elymus junceus
Lolium perenne
Phleum pratense
LEGUMES:
Alfalfa, RANGER/VERNAL
Alfalfa, Travois
Birdsfoot Trefoil EMPIRE
Crownvetch, Emerald
Hairy Vetch
Lespedeza, Korean
Red Clover, medium
Alsike Clover
White Clover
Medicago sativa
Medicoa spp.
Lotus corniculatus
Coronilla varia
Vicia villosa
Lespedeza stipulacea
Trifolium pratense
Trifolium hybridum
Trifolium repens
99
99
98
98
96
98
99
99
98
90*
90*
85*
70*
85*
80*
90*
90*
90*
Avena sativa
Secale cereale
Sorghum vulgare var.
sudanese
97
97
98
90
90
85
NURSE CROP OR STABILIZING
CROP:
Oats
Rye
Sudangrass, PIPER
*Includes hard seed.
SEEDS
COMMON NAMES, SCIENTIFIC NAMES, and PLS
Common Names
Scientific Names
PLS
(%)
NATIVE GRASSES:
Big Bluestem - Kaw, Pawnee, Roundtree
or Champ
Little Bluestem - Blaze, Aldous or
Camper
Switchgrass - Blackwell, Pathfinder,
Cave-in-Rock or Nebr. 28
Indiangrass - Neb. 54, Oto, Holt or
Rumsey
Sideoats Grama - Trailway, Butte or El
Reno
Western Wheatgrass - Barton or Common
Buffalograss - Texoka or Sharp's
Improved
Sand Bluestem - Champ or Goldstrike
Blue Grama
Intermediate Wheatgrass
Slender Wheatgrass
Prairie Dropseed
Sand Dropseed
Sand Lovegrass
Weeping Lovegrass
Hairy Wood Chess
Blue-joint grass
Bottlebrush sedge
Tussock sedge
Fox sedge
Virginia wild-rye
Reed manna grass
Fowl manna grass
Common rush
Rice Cut Grass
Rye grass, annual
Fowl bluegrass
Green bulrush
Wool grass
Soft-stem bulrush
Indian grass
Spike Rush
Andropogon gerardii
Andropogon scoparius
Panicum virgatum
Sorghastrum nutans
Bouteloua curtipendula
Agropyron smithii
Buchloe dactyloides
Andropogon gerardii, var.
paucipilus
Bouteloua gracilis
Agropyron intermedium
Agropyron trachycaulum,
var. unilaterale
Sporobolus heterolepis
Sporobolus cryptandrus
Eragrostis trichodes
Eragrostis curvula
Bromus purgans
Calamagrostis canadensis
Carex comosa
Carex stricta
Carex vulpinoidea
Elymus virginicus
Glyceria grandis
Glyceria striata
Juncus effusus
Leesia oryzoides
Lolium italicum
Poa palustris
Scirpus atrovirens
Scirpus cyperinus
Scirpus vallidus
Sorghastrum nutans
Eleocharis palustris
30
30
63
30
30
56
60
30
30
70
70
65
65
65
65
60
47
62
78
64
60
50
72
80
62
89
72
45
78
78
60
71
FORBES:
Canada anemone
Marsh milkweed
New England aster
Swamp aster
Showy tic-trefoil
Joe-pye weed
Boneset
Ox Eye sunflower
Blue-flag iris
Meadow blazingstar
Tall blazingstar
Great blue lobelia
Reed manna grass
Fowl manna grass
Common Rush
Rice Cut Grass
Anemone canadensis
Asclepias incarnata
Aster novae-angliae
Aster puniceus
Desmodium canadense
Eupatorium maculatum
Eupatorium perfoliatum
Heliopsis helianthoides
Iris virginica-shrevii
Liatris ligulistylis
Liatris pycnostachya
Lobelia siphilitica
Glyceria grandis
Glyceria striata
Juncus effusus
Leesia oryzoides
72
25
25
25
25
66
41
38
19
24
24
13
50
72
80
62
The accumulative total of Pure Live Seed (PLS) is the product obtained
by multiplying the pounds (kilograms) of each seed by the purity and
germination percentages expressed as decimals. Calculations will be
based on test results of samples taken by the Contracting Authority. If
the seeds were not sampled or if these test results are not available,
the PLS will be calculated from information shown on the label.
4169.03 FERTILIZER.
Fertilizer shall be of the grade, type, and form specified and shall
comply with rules of the Iowa Department of Agriculture and the
following requirements:
The grade of fertilizer will be identified according to the
percent nitrogen (N), percent available phosphoric acid, (P2O5),
and percent water soluble potassium, (K2O), in that order, and
approval will be based on that identification.
All fertilizer shall be furnished from an established fertilizer
dealer and guaranteed analysis shall be provided through
mechanically printed commercial fertilizer bags or a
manufacturer's (not a distributor's) bill of lading.
Inspection and acceptance of fertilizer will be in accordance
with Materials I.M. 469.03.
Fertilizer shall be of a type that can be uniformly distributed
by the application equipment. When applied by hydraulic methods,
fertilizer may be chemically combined or may be furnished as
separate ingredients. When applied by other means, each unit of
fertilizer shall be chemically combined, and the manufacturer's
guarantee shall indicate compliance with this requirement.
Fertilizer may be furnished in a dry or liquid form.
The Contractor shall furnish a list of the number of containers
and a corresponding scale ticket from an approved scale for the
fertilizer to be used in the work.
Official samples taken by the Contracting Authority may be
tested. A tolerance of minus 1.0 percentage point from the
guaranteed analysis for each nutrient will be considered
substantial compliance.
Ground limestone shall be of the type known as No. 1 fine (70%
passing No. 200 (75 µm) sieve) with an analysis of elemental
calcium of not less than 37% nor more than 40%.
4169.04 INOCULANT FOR LEGUMES.
An inoculant is a culture of bacteria specifically formulated for
legume seeds (alfalfa, clovers, lespedeza, birdsfoot trefoil, hairy
vetch, and crownvetch). The manufacturer's container shall indicate the
specific legume seed to be inoculated and the expiration date. All
inoculant shall meet requirements of the Iowa Seed Law. Safety
precautions specified on the product label shall be followed.
4169.05 RESERVED.
4169.06 STICKING AGENT.
A sticking agent shall be a commercial material recommended by the
manufacturer to improve adhesion of inoculant to the seed. For
quantities less than 50 pounds (25 kg), the sticking agent need not be
a commercial agent, but shall be approved by the Engineer and shall be
applied separately prior to application of inoculant. Safety
precautions specified on the product label shall be followed. A
sticking agent is not required if a liquid formulation of inoculant is
used.
4169.07 SOD.
Sod shall consist of approximately 1 inch (25 mm) of well established
turf consisting of live Kentucky bluegrass, unless otherwise specified.
Sod shall be free from roots of trees or brush, stones, and other
objectionable materials. Sod shall be free from all noxious weeds and
reasonably free of all other weeds.
Sod shall be cut in strips of uniform width and thickness with ends
square. The Engineer may order the thickness adjusted to meet the sod
conditions. Sod shall be cut to the length specified for the use
intended. If not specified, the minimum length shall be 3 feet (1 m).
All sod areas shall be mowed to a height of approximately 1 1/2 inches
(40 mm) to 2 inches (50 mm) prior to cutting.
Sod shall have been regularly maintained prior to cutting. The
Contractor shall be responsible for the application of pre-emergence
weed control chemicals and weed control chemicals for broadleaf weeds.
Within 1 hour after being cut, sod shall be rolled or stacked. Other
methods of handling sod may be approved by the Engineer. Precautions
shall be taken to prevent drying or heating. Sod damaged by heat or dry
conditions, or sod cut more than 18 hours before being incorporated
into the work, shall not be used.
Sod will be subject to inspection by the Engineer at the job site, and
approval of the work constitutes approval of the material.
4169.08 MULCH.
Material used as mulch may consist of threshed or unthreshed hay,
threshed or unthreshed prairie hay, threshed cereal straw, wood
excelsior, wood cellulose, or other material, as specified. All
material used as mulch shall be free from noxious weeds.
The Contractor shall furnish a list of the number of bales and
corresponding ticket from an approved scale for the mulch material to
be used on the project.
Wood excelsior shall be composed of wood fibers, a minimum of 8 inches
(200 mm) long, based on an average of 100 fibers, and approximately
0.024 inch (600 µm) thick and 0.031 inch (800 µm) wide. The fibers
shall be cut from green wood and shall be reasonably free of seeds or
other viable plant material. Wood excelsior shall be baled and the
weight (mass) determined. The weight (mass) of the material shall be
furnished by the manufacturer and shall be used for determining the
rate of application.
4169.09 STAKES FOR HOLDING SOD.
Stakes for holding sod shall be either wood or metal, except that wood
stakes shall be used in sandy soils or when required by the Engineer.
Wood stakes for holding sod shall be 1 inch (25 mm) to 1 1/2 inches (40
mm) in width, 1/4 inch (6 mm) to 1/2 inch (13 mm) in thickness, and 12
inches (300 mm) long. Where this length of stake does not provide firm
bearing, the Engineer may require stakes of sufficient length to secure
firm bearing.
Wire stakes shall be in the form of staples made from No. 11 (3.06 mm
diameter) wire or heavier and shall have a minimum 2 inch (50 mm) flat
spread on the top of the sod. The legs shall be at least 6 inches (150
mm) in length. The Engineer may require wire legs longer than 6 inches
(150 mm).
4169.10 SPECIAL DITCH CONTROL AND SLOPE PROTECTION.
Jute mesh, plastic netting, wood excelsior mat, and wire staples shall
comply with the following:
A. Jute Mesh Over Sod.
Jute mesh over sod shall be a uniform, open, plain weave, of
single jute yarn. The yarn shall be of loosely twisted
construction and shall not vary in thickness by more than 50% its
normal diameter. Jute mesh shall be furnished in rolled strips
and shall meet the following minimum requirements:
Jute mesh shall be nontoxic to the growth of plants and
germination of seeds and shall be identified by tag.
Width - minimum 48 inches ± 1 inch (1.2 m ± 25 mm) from
manufacturer's rated width.
78 warp ends per 4 feet (1.2 m) of width.
45 weft ends per yard (meter).
Weight (mass) to average 1.22 pounds per linear yard (0.6
kg per meter) (based on 48 inch (1.2 m) width) with a minus
tolerance of 5%.
All material must be new and unused.
At the Contractor's option, plastic netting (polypropylene) may
be substituted for jute mesh. It shall meet the following
requirements:
Color - black or green, with UV additives
Mesh size - approximately 0.6" x 0.7" (15 mm x 18 mm)
Weight (Mass) - approximately 9 pounds per 1,000 square
feet (44 g/m2)
Width - 48 inches (1.2 m) minimum
B. Wire Staples.
Wire staples for holding special ditch control wood excelsior mat
and special ditch control jute mesh over sod shall meet the
following requirements:




Wire staples shall be U-shaped.
Length of each leg shall be 6 inches (150 mm) minimum.
Wire diameter shall be No. 11 (3.06 mm) wire.
Staples shall be of sufficient hardness to facilitate
installation without bending. In sandy soil conditions,
wire staples with a minimum length of 12 inches (0.3 m)
will be required when directed by the Engineer.
C. Wood Excelsior Mat.
Wood excelsior mat shall meet the requirements of Materials I.M.
469.10.
Wood excelsior mat shall be a mat of interlocking wood fibers
with a plastic netting applied to both sides for holding the
excelsior in place. The mat shall be nontoxic to growth of plants
and germination of seeds. The netting applied to both sides shall
have a mesh size of approximately 5/8 inch by 3/4 inch (16 mm by
19 mm). The mat shall be furnished in rolls with a minimum length
of 180 feet (55 m) and a uniform, minimum width of 48 inches (1.2
m), within a tolerance of minus 1 inch (25 mm) and plus 3 inches
(75 mm). As furnished, the mat shall have a minimum weight (mass)
of 0.88 pound per square yard (480 g/m2). The mat shall be
furnished in plastic bags or otherwise protected to prevent
damage from weather or handling.
At the Contractor's option, straw-coconut fiber mat or coconut
fiber mat may be substituted for wood excelsior mat for special
ditch control, and straw mat, straw-coconut fiber mat or coconut
fiber mat may be substituted for wood excelsior mat for slope
protection. These mats shall meet the following requirements:
The mat shall be of consistent thickness with the straw,
straw-coconut fiber or coconut fiber evenly distributed
over the entire area of the mat. The top side of the mat
shall be covered with a polypropylene netting with a 3/8
inch by 3/8 inch (9.5 mm by 9.5 mm) mesh attached with
cotton thread. The mat shall be furnished in rolls with a
minimum width of 47 inches (1190 mm) and a minimum length
of 80 feet (24 m). As furnished, the mat shall have a
minimum weight (mass) of 0.50 pound per square yard (270
g/m2). The mat shall be furnished in plastic bags or
otherwise protected to prevent damage from weather or
handling.
Antimicrobial Techniques for Medical
Nonwovens - A Case Study
By W. Curtis White, Bioproducts Technology Manager, Dow Corning Corporation,
Dr. Jerry M. Olderman, Vice President/Research and New Business Development, American Convertors
Introduction
The nonwovens industry is challenged by
the presence of microorganisms and the
negative effects they cause. Deterioration,
defacement and odors are all dramatic effects
which occur from the microbial contamination
of nonwovens. Nonwovens can also act as a
"harbor" as most they offer ideal environments
for medically significant microorganisms. The
ability to make nonwovens resistant to
microbial contamination has advantages in
many applications and market segments. This
is especially true in medical markets where
nonwovens have already contributed a degree
of aseptic sophistication beyond historically
used linens.
Nonwovens used in medical applications
have unique microbial problems and their
control is a complex microbiological task. Use
of nonwovens in the United States medical
community has greatly expanded in recent
years as evidenced by the fact that over half of
the drapes used in surgery are nonwovens.
The microbiological integrity of nonwovens
has been the object of numerous studies
ranging from the sterilization of nonwovens to
the evaluation of the barrier properties of
nonwovens. Test data generated with
nonwovens generally support the fact that
nonwovens contribute positively to the
reduction of microorganisms in the medical
environment. This contribution has been part
of the medical communities awareness of the
benefits of and actions aimed at improving the
hygienic nature of their environment as they
take steps towards asepsis.
History
The surgical arena provides a valuable
model for illustrating the medical communities'
challenges as regards asepsis. The first
surgery may have occurred nearly twelve
thousand years ago. Laws regarding the
performance and liability of surgeons were
included in the code of Hammurabi in 1700
B.C. with mention of such retribution as the
surgical removal of the hand of the physician
whose patient lost an eye or succumbed to the
procedure.
The first use of the word inflammation
appears to date back about twenty-five
hundred years and is mentioned in three
tablets from Assurbanipal's library.1 The
ancient Greeks mistook infection as a "...good
and natural course of events" and poured wine
into wounds to help them heal.2 It is only
coincidental that the disinfecting properties of
wine are based on a chemistry very similar to
that of Lister's phenol, but we come full circle
when we recall that Pasteur's work on
preventing wine spoilage led to Lister's
theories.3 It was not until the last quarter of the
nineteenth century, after Semmelweiss had
died, Oliver Wendell Holmes had written of the
risks of bacterial contamination, and Lister had
laid the ground work for surgical asepsis, that
the first surgical drapes and apparel came into
use. Three-quarters of a century after Neuber
and Robb4 initiated the use of linens, the first
nonwoven drapes were introduced in the
United States, and a second tier of wound
isolations (asepsis) was attained.
Because the medical literature is replete
with studies on the epidemiology, rate and
cost of post-operative infection, this review is
intended to bring into focus the position stated
on aseptic barrier materials and their impact
on infection. While there may be little
agreement on the specifics of such factors as
infection rate and costs, and the relative
importance of the numerous individual
parameters and complex interactions which
impact wound infection, it is putative that the
strict observation of sterile technique and the
proper application of drugs and devices can
reduce infection rate. One excellent review5
refers to the five D's or O.R. infection control:
discipline, defense mechanisms, drugs, design
and devices, and outlines a cogent basis for
reducing risk of infection.
Summary of the Literature
In 1952, Beck proved that bacteria pass
through layers of absorbent linen with
"instantaneous rapidity", but a nonwoven
material, treated with a water repellent finish,
resisted bacterial transmission and appeared
to be "ideal as a bacterial barrier6.
Twenty-six years after this remarkable
discovery, Dr. Beck was still exhorting the
reader to employ a draping system that would
resist the passage of aqueous solutions7.
During that quarter of a century, as the quality
of nonwoven materials were improved and the
variety of surgical drapes and apparels for use
in all types of operations was expanded,
several other investigators began to evaluate
and compare these new single use
nonwovens to conventional absorbent 140
thread count linen (muslin) as well as the new
more recent 270 plus thread repellent woven
product (Pima).
In 1964, Sweeney reported that the
nonwoven drape he tested on nearly twelve
thousand infant deliveries "might serve as a
more effective barrier to pathogen migration
than the traditional cotton drape", and
adjudged the disposable nonwoven drape to
be a superior aseptic barrier to the bacterial
migration in obstetrics patients.8
In 1969, Peter Dineen showed the
superiority of disposable nonwovens to linens
in the reduction of air borne contamination by
90%, and in 1973 he demonstrated the
prevention of bacterial penetration in liquid
media "purely on the basis of the water
repellency" of the nonwoven material. 9, 10
Again in 1973, the superiority of nonwoven
materials to muslin was demonstrated by
Alford, et,al., at Indiana University. They found
a 33% reduction in colony counts on the
surface of gowns after 30 minutes of
exercise.11
The need for this quality in a gown was
supported by the work of Charnley and
Eftekhar who in 1969 reported that "organisms
shed by the surgeon's body may penetrate
operating gowns, and by direct contact, infect
operative wounds."12
Several other studies probing this premise
followed in rapid succession. In 1979, Ha'Eri
and Wiley used human albumin microspheres
as tracer particles to demonstrate that
nonwovens were superior to muslin in
preventing bacterial penetration and reducing
the risk of wound contamination. In onehundred-ten orthopedic operations, not one
tracer particle which had been sprayed on the
patient's skin and the surgeon's chest and
shoulders, was detected in the wound when
nonwovens were used. The number of tracer
particles observed when muslin was employed
varied with the length of the procedure and the
degree of physical strength during surgery, but
all wounds were contaminated.13
Whyte, et.al., found in laboratory studies
that the use of nonwovens reduced surface
count contamination by fifty to sixty percent
over closely woven "ventile cloth," which is the
British version of the pima fabric.14 Further
support came from the work of Hamilton,
et.al., published in 1979. Under "clean room"
O.R. conditions with five-hundred-ninety-five
orthopedic cases, they showed that viable
organisms from the surgical team, which they
claimed can account for twenty percent of
wound contamination, penetrated one out of
every ten gowns comprised of closely woven
repellent Pima and conventional muslin
fabrics. In four out of nineteen wounds
(21.1%) that were contaminated, the identical
organisms were found on the external surface
of the gowns as well.15
Finally, J. Moylan, et al., in 1975 and again
in 1980, reported similar results on linen and
nonwoven gowns. In the earlier study, Moylan
reported external gown contamination
increasing from 23% to 76.5% on the
nonwoven gown compared to 85.2%
increasing to 94.4% with muslin over the
period of one to four hours of surgery in one
hundred cases.16 In 1980, Moylan and
coworkers published clear clinical evidence of
the superior efficacy of a nonwoven gown over
both muslin and Pima repellent treated linen
gowns. After an eighteen month study with
2,253 consecutive surgical operations in two
different hospitals, the infection rates reported
were: 4.75% for Pima gowns versus 1.83% for
the nonwoven in Hospital A, and 8.2% for
muslin versus 3.07% for the nonwoven in
Hospital B.17
Hartman also reported the reduction in postoperative infection rates from 6.5% to 1.0% at
Gillette Hospital when new aseptic techniques
were introduced in combination with the
application of nonwoven drapes over a seven
year period.18
These results are not surprising in the light
of recent laboratory testing reported in the
literature. For example, H. Laufaman, et.al.,
compared nonwovens to Pima fabrics under a
static pressure head of liquid containing
bacteria. They reported that polyethylene
reinforced nonwovens may be considered
suitable for lengthy, wet operations and found
no significant difference in performance
between a reinforced nonwoven system and
the treated Pima cotton.19
In April 1980, Schwartz and Saunders
reported on both lab testing and clinical
comparisons of muslin and Pima cotton as
well as two different nonwovens.
They found that the treated Pima and the
two nonwovens were effective barriers and
suggested that, in their opinion, there would
be a reduction in infection with the use of any
of these three materials.20
While a great number of factors influence
the rate of post-operative infection, certainly
the reduction in wound contamination is one of
the most critical. Davidson, et.al., studied
fifteen different variables of techniques with
1,000 patients and reported that "a wound
which gave a positive culture at the end of the
operation has a 47.9% greater chance of
becoming infected than a wound found to be
sterile at closure."21 One philosophy that these
investigators, and others who have evaluated
surgical materials, agree upon is that muslin is
unacceptable as a bacterial barrier material.
Indeed, it has been stated that muslin will not
bar passage of bacteria either wet or dry, even
for a few minutes. Thus the risk of wound
contamination is significant when muslin is
used. In fact, the Technical Standards
Committee of the AORN has published a brief,
but comprehensive set of standards for
surgical drapes and gowns which require
blood and aqueous fluid resistance.22
There is less agreement on which of the
other surgical drapes and gown materials on
the market today is more or less suitable. You
have seen a review of most of what has been
done to evaluate the performance in terms of
wound infection under controlled clinical
conditions, but there is still no consensus on
which of many laboratory, physical or
microbiological tests does the best job of
evaluating them. In fact, there is no clear
definition on the specific variables such as
time, liquid typed, pressure, stress and so
forth that should be tested and at what level.
The only direction on that topic was developed
by an ad hoc committee of industry in
conjunction with the American College of
Surgeons. This work has been continued by
INDA, the Association of the Nonwovens
Industry, and AAMI in response to the
challenge that surgical materials should be
"impervious to the penetration of bacteria
under the usual conditions of use."
Newer materials are being developed to
respond to the needs of the surgical team.
These materials offer more comfort and better
performance with little or no sacrifice to their
efficacy in restricting the passage of bacteria.
In fact, recently a third tier of aseptic barrier
materials, one which contains an antimicrobial
agent, has been introduced for use in surgery.
This material is directed at reducing the
amount of contamination transferred to the
wound from the surgical team, through scrub
clothing and gowns, onto the sterile field or by
the endogenous bacteria, deposited on the
surface of the drape during surgery and then
transferred into the subcutaneous region of
the wound where it can increase the risk of
infection.23, 24
This third tier of aseptic barrier materials
addresses itself to the critical dose variable in
the Altemeier and Culbertson equation which
expresses that, "wound infection is the
unfavorable result of Dose of Bacteria times
Virulence divided by the Resistance of the
Patient."25 Analysis of this formula shows that
the dose variable is the one variable, i.e. when
bacteria were present at closure the risk of
nosocomial infection increased significantly. 26
Robeson's work with skin graft patients clearly
showed the importance of dose as expressed
by infectious threshold levels of greater than
105 and 106 bacteria per gram of tissue. The
logic and evidence that reducing the dose
(level) of microorganisms in the field of the
wound site will reduce the risk of postoperative infections is irrefutable.
The desirable performance characteristics
of this third tier antimicrobial nonwoven drape
are that the antimicrobial nonwoven drape
reduces the level of bacterial contamination,
controls and/or kills the bacteria commonly
associated with surgical wound infections,
takes an active role in maintaining an aseptic
field at the wound site, that the antimicrobial is
safe to the staff and the patient, that the
fabric's antimicrobial activity is unaffected by
common sterilization procedures, and that the
fabric retains all of the positive handling and
appearance characteristics desired by the OR
and surgical staff. In 1978, American
Convertors and Dow Corning Corporation
undertook the challenge of developing a fabric
that met the above needs.
This paper discusses the microbiological
techniques employed in the development of
the American Convertors ISOBAC
Antimicrobial Fabric (AC-AM Fabric) which
utilized Dow Corning 5700 antimicrobial agent
(now known as AEM 5700 Antimicrobial)
(silanequat), the properties of this unique
antimicrobial agent, the safety profile of this
chemistry and this state-of-the-art fabric, as
well as the effectiveness of the AC-AM Fabric.
The Chemical Technology
The antimicrobial activity of certain silanemodified surfaces was discovered during a
screening project in which the minimum
inhibitory concentrations (MIC) for bacteria
were being determined for various Dow
Corning products and research materials.
Repeat testing in the same glassware
revealed that the glassware itself had become
antimicrobial. Continued investigation led to a
series of U.S. patents and publications
covering this class of materials as broadspectrum algicides, bactericides, a fungicides
when applied to solid substrates. Further
examination of this phenomenon and the
chemistry involved resulted in the preparation
of a single material which was more
extensively evaluated. This material is
chemically, 3-trimethoxysilylpropyloctadecyldimethyl ammonium chloride
(silanequat).
AEM 5700 offers users the following
features:

Good durability - In the presence of
moisture, AEM 5700 antimicrobial agent
imparts a durable, broad spectrum,
biostatic surface finish to a wide range of
substrates. It is leach resistant, nonmigrating, and is not consumed by
microorganisms. Broad spectrum activity Effective against gram positive and
negative bacteria, fungi, algae, and
yeasts.

Increased efficiency - Through proper
application, durable bacteriostatic and
fungistatic and algistatic surfaces can be
attained with a minimum amount of Dow
Corning 5700 antimicrobial agent.

AEM 5700 antimicrobial agent can be
applied to organic or inorganic surfaces as
a dilute aqueous solution to give 0.1-1.0
percent by weight of active ingredients.
Aqueous solutions can be prepared by
simply adding the antimicrobial agent to
water while stirring.

Surfaces can be treated with the aqueous
by dipping, padding, or by automated
spraying until adequately wet, or applying
by foam finishing techniques.
After applying the antimicrobial agent, the
surface should then be dried to effect
complete condensation of silanol groups at the
surface and to remove water and/or traces of
methanol from hydrolysis. Optimum
application and drying conditions such as time
and temperature should be determined for
each application before use in a commercial
process.
The first commercial application, on men's
socks, helped prevent microbially caused
deterioration and defacement and reduced
sock odor associated with the proliferation of
microorganisms. A paper by Gettings and
Triplett presented conclusive evidence that the
antimicrobial feature provided a significant
reduction in sock odor and that the protection
afforded by the treatment was not significantly
diminished even after repeated launderings.27
Mechanisms of attachment to surfaces,
general treatment phenomena, and
performance profiles have also been
previously presented by Malek and Speier and
will not be detailed in this paper.
AEM 5700 is registered with the EPA
(#64881-1) for use as a pesticide on
numerous substrates. This chemistry has also
been reviewed by the F.D.A. and is listed as a
modifier of medical devices under the 510(k)
procedures.
Safety Profile
Safety considerations regarding the use of
an antimicrobial on a surgical drape
fenestration offers a model where the severity
of risk to health is magnified beyond the risks
encountered on less critical goods such as
CSR wraps, table covers, or the like. This is
especially relevant as one remembers that
antimicrobials, by definition and function,
inhibit and/or kill living things. The mode of
biological involvement needs to be fully
understood so that a proper balance between
risks and benefits can be made.
The ability of the silanequat to chemically
bond to the nonwoven substrate and still
provide for the broad spectrum control of
microorganisms made it well suited to the
safety challenges encountered in this
application, but a large body of toxicological
data still needed to be generated. Considering
the life history of the fabric, the key
toxicological tests revolved around the
toxicological profile of the silanequat itself and
the AC-AM Fabric in use near an open wound
site.
The following studies have been conducted
with the silanequat:

(a) acute oral

(b) acute ocular

(c) acute and subacute dermal

(d) acute vapor inhalation

(e) primary skin sensitization and
irritation

(f) sub-acute vaginal irritation

(g) four-day static fish toxicity

(h) teratogenic evaluation

(i) sub-acute human wear test (socks)

(j) human repeated insult patch test,

(k) in-vitro Ames Microbial Assay with
and without metabolic activation

(l) in-vitro mammalian cell transformation
in the presence and absence of
exogenous metabolic activation,

(m) in-vitro Host-Mediated Assay

(n) a percutaneous absorption study.
Although certain handling cautions are
indicated by data from the above tests, no
untoward effects are notable regarding treated
substrates.
Routine quality assurance specifications
were also put into place to assure uniformity,
durability, and efficacious nature of the AC-AM
Fabrics.
The AC-AM FAbric was further subjected to
the following pre-clinical biocompatibility tests
which are considered appropriate for skin
contact medical products:
Efficacy Profile

(a) Tissue culture (cytotoxicity), to
determine if a tissue culture medium (with
serum) eluate of the test material can
induce a cytopathic effect on monolayers of
human (WI-38) cell

(b) Acute systemic toxicity to evaluate the
potential of a single injection of an extract
of the test material to produce a systemic
toxicity response

(c) Intracutaneous irritation to evaluate the
potential of a single injection of the test
material extract to induce tissue irritation

(d) Eye irritation to determine the response
of the rabbit eye to the instillation of specific
extracts of the test material

(e) Hemolysis to determine if a substance
can be extracted from the material which is
capable of inducing hemolysis of human
red blood cells

(f) Human Repeated Patch Test to
determine if the test material is capable of
inducing skin irritation and sensitization
under controlled patch test conditions

(g) Extensive leachability studies to
evaluate the durability and non-leaching
potential of the chemically modified fabric
when exposed to copious amounts of
physiological saline, water and simulated
human sweat.
The final results of these biocompatibility
studies indicate that AC-AM Fabric is nontoxic, non-irritating and non-sensitizing to
human skin, and has a permanent
antimicrobial capacity which cannot be
extracted in use. These pre-clinical studies
provide sufficient information to allow us to
predict the biocompatibility of the finished
products and support their safe clinical use. As
such, AC-AM Fabric is considered safe for use
in surgery. Four years of clinical use with no
untoward effects also supports the suitability
of the AC-AM Fabric for its intended use.
Parallel to the safety work, a considerable
body of microbiological efficacy data were
being generated. To support the effectiveness
of this third tier "active nonwoven" a variety of
microbiological tools were utilized. These
include: in-vitro tests, Scanning Electron
Microscopy (SEM) work, and clinical
evaluations. The purpose of these tests are to
support claims relating to the reduction of
microbial dose on the drape in the vicinity of
the wound. The AC-AM Fabric kills the
bacteria commonly associated with surgical
wound infections and takes an active role in
maintaining an aseptic field at the wound site.
The antimicrobial surface serves to isolate the
wound from bacterial transfer from the drape
surface. The antimicrobial component of the
AC-AM Fabric is chemically bonded, safe for
use in surgery, and does not lose its
effectiveness when sterilized, stored, or
handled during the manufacturing procedure
or in surgery.
Test Techniques - In vitro Barrier
Fabric
Initial efforts in the development of the
antimicrobial nonwoven fabric were aimed at
using 3-trimethoxysilylpropyldimethyloctadecyl
ammonium chloride on a barrier drape to
provide a more hygienic field. Classical
microbiological methods did not work to
demonstrate efficacy because solution activity
as demonstrated in the Minimum Inhibitory
Concentration Test (MIC) was irrelevant to a
bound antimicrobial and since the antimicrobial agent did not leach the zone of
inhibition test was not appropriate30 and
padding tests31 did not have utility without the
use of very sophisticated wetting agents.
Linking these laboratory tests to "real world"
performance was nearly impossible.
MIC TESTS (TABLE I)
Although the silanequat is not an efficient
solution active antimicrobial, the obligatory
MIC tests have been run. Results of these
tests show clearly the broad spectrum activity
of the silanequat. Interpolation of these data to
the real world is dangerous since the chemical
nature of the silanequat makes any water
solution testing dynamic. Chemically, the
silanequat in water is constantly bonding and
unbonding with itself and any reactive
surfaces available. This "living polymer" nature
of the material in water solution makes MIC
data extremely variable depending on the
design of the test protocol and the handling of
the test solutions.
Figure 1 below clearly shows this benefit as
compared to a traditional leaching type of
antimicrobial.
ZONE OF INHIBITION TEST
The zone of inhibition test, when a zone is
produced, shows that the antimicrobial is not
durable. This increases the risk of toxicological
involvement and the risk of mutational or
inductive adaptation phenomena being
manifested. Although the silanequat does not
give a zone of inhibition, encroachment of the
test organisms onto the test surface is
eliminated. The fungal control demonstrated in
Note the durability evidenced by the
continued activity of the silanequat after five
home launderings of the cotton fabric whereas
the traditional leaching type of antimicrobial
treated surface no longer shows any
protection against the test organism. This
fungal activity and durability are well suited for
many nonwoven applications. Table II shows
typical results from the AATCC-30 Fungicide
Test Protocol and further supports this
important property.
PADDING TESTS
The utility of padding type protocols to testing
the original silanequat treated barrier fabric
seemed appropriate except for the
hydrophobic nature of the treated fabric. This
introduced considerable error into the testing
and modification of the AATCC-100
antimicrobial test protocol to include
sophisticated wetting agents was necessary.
Padding tests are useful as an indicator of
surface antimicrobial activity but are difficult to
run reproducibly and are extremely operator
sensitive. Typical results using the AATCC100 protocol plus re-wetter are shown in Table
III. A number of variations of this test have
utility in understanding the antimicrobial
activity of nonwovens and will be discussed
later.
DYNAMIC SHAKE FLASK TEST
To overcome the testing problems associated
with the hydrophobic nature of the test surface
FIGURE 1
and yet maintain some linkage to "real world"
dynamics, American Convertors, using a
modification of the classical rotating tube test,
developed a dynamic shake flask test. This
test has been modified as follows by Dow
Corning: The test utilizes a 150ml.
Ehrlenmeyer flask in which 5 ml. of a liter of 1
x 105 to 3 x 105 CFU/ml. (as Colony Forming
Units) of test organism is added to 70 ml. of
phosphate buffer or other test solutions and a
measured amount of test fabric. This system is
then placed on a Burrell Wrist Action Shaker
for a representative time period. Zero time and
test time control and treated samples are then
compared for percent reduction. Results from
this testing showed that the fabric could be
treated durably and uniformly with Dow
Corning 5700 and that the fabric was effective
against both gram negative (Klebsiella
pneumoniae) and gram positive
(Staphylococcus aureus) bacteria. Data
generated using this test protocol can be seen
in Table IV. Clinical isolates were used as the
test organisms. Note the effective range was
from 93.6% - 99.9% reduction for these
organisms commonly found in hospital
situations. Since the innoculum control
showed the organisms to be healthy, one
could assume that those organisms that
showed reduction with the untreated controls
were sensitive to some component of the
fabric or were trapped within the fabric and
therefore, not recovered.
BARRIER FABRIC DISCUSSION
Although these results were encouraging, a
marketing reality had to be faced in that the
marketplace preferred a drape that had an
absorptive fenestration. Absorptive
fenestrations had been avoided by American
Convertors because of the potential reservoir
or organisms that could build up during typical
surgical procedures. Armed with a safe
antimicrobial system, consideration of an
absorptive fenestration could be made with the
risk of increasing the microbial dose minimized
or eliminated. Fabric design was optimized
using technology jointly developed with
Burlington Industries but safety and
microbiological testing still presented a
challenge.
Test Techniques - In Vitro
Absorptive Fabric
Fabric design, application procedures,
safety, and antimicrobial efficacy are critical to
the utility of the final nonwoven product. Once
the fabric design, application procedures, and
safety considerations had been completed,
efficacy evaluations of the AC-AM Fabric were
undertaken.
Padding Tests
As described earlier, various modifications
of the AATCC-100 test have been used to
demonstrate the effectiveness of the AC-AM
Fabric. Listed in Table V are results from a
fluid compatibility test run using buffered
phosphate, saline, and serum. The
K.pneumoniae microbial dose was added to
each of the test fluids and then aliquots were
applied to treated and control fabrics. Results
were very uniform and confirm that microbial
loads from such fluids are readily controlled on
the AC-AM Fabric.33
The above work was extended in an
attempt to compare the antimicrobial
effectiveness of several types of fabrics where
reinoculated blood and defibrinated blood
were used as the carrier mediums. The test
organism was Klebsiella pneumoniae ATCC
4352. Innoculum level was 1.5 x 105 CFU/ml.
Note that results in Table VI (whole blood
testing) show a rather uniform loss of
retrievability of the test organisms irrespective
of test substrate. This was attributed to the
effects of the blood clotting through time
removing the organisms from retrieval and in
fact killing most of them. The killing effects of
the blood and also defibrinated blood were
further studied by following the course of an
insult of K. pneumoniae, on linen. (Table VII)
Results show clearly the die-off effect in the
whole blood, whereas no significant effect can
be seen with the defibrinated blood through
the six hour test period. Note that the linen
inoculated with the contaminated blood
extended the life of the test organisms. The
significance of the 100% reduction in 5 min. on
the D Sample (ISO-BAC, Table VI) needed to
be established so an additional test was run
using defibrinated blood. Table VIII contains
their results of this testing. The clear value of
reducing microbial dose level is illustrated in
these results. Whereas neither the linen (A)
nor the two untreated nonwovens (B and C)
showed any reduction of the test organisms
through two hours the ISO BAC Fabric
showed a 59% reduction in 30 minutes and
72% reduction after two hours. These tests
were very rigorous in terms of organic load
and microbial load and yet bacterial dose
levels were significantly reduced.
To expand on our understanding of the
influence of fluids a padding test was
undertaken using Clark-Lubs solution
(KH2PO4/NaOH) and the Acta "Sweat" as prewetting agents and the carrier fluids for
Staphylococcus epidermidis. (Table IX) Again,
the results support the excellent antimicrobial
activity of the AC-AM Fabric.34
One of the most thorough studies utilizing
the AC-AM Fabric was conducted by W.U.
Faber et.al. at the West German Institute for
Hospital Hygiene and Infection Control.35
Their test protocol, a swatch pad test, utilized
linen, Molnlycke, and ISO-BAC Fabrics, four
bacterial strains (S. aureus, Streptococcus
faecalis, K. pneumoniae, and P. aeruginosa),
three solutions used to stimulate O.R.
conditions (buffered water, physiological
saline, and blood serum), and five retrieval
time intervals (0, 15 min., 30 min., 60 min.,
and 120 min.). The innoculum concentration
was 1 x 105 to 1 x 106 CFU/ml. inoculated
onto a 5 x 5 in. test fabric swatch. "All test
bacteria and solutions indicate that the highest
bacteria reduction occurred with the ISO-BAC
Fabric in all cases. It is obvious that in linen
and non-textile drape material, the bacterial
kinetics show only minor differences, whereas,
in ISO-BAC, the bacterial count is significantly
lower when compared to the initial count. It is
assumed that when using ISO-BAC materials,
a transmission of bacteria by means of the
draping material is prevented to the highest
possible extent."
Pulse Height Analysis 36
The effectiveness of AC-AM Fabric in
reducing and controlling pathogenic organisms
(commonly occurring in the operating theater)
is of prime importance. Therefore, tests to
evaluate the performance of AC-AM Fabric
against Escherichia coli and Staphylococcus
aureus were performed using Sontara and a
suspension of the test organisms alone as a
control. Two suspending media, saline and
phosphate, were used and each combination
was treated in triplicate.
In previous experiments, agar plate counts
to establish the reduction of viable bacteria
had been the method of choice. In this study,
another approach using a modified particle
counter was employed. This procedure takes
samples from the flasks containing the
swatches and bacterial control and processes
the samples through the particle counter
instead of making plate counts. The particle
counter is modified to focus on bacterial sized
particles, counts and sizes particles aspirated
through an orifice, automatically recording the
data on the numbers and size of the particles
in 50 ml aliquots of the sample.
These data are presented both as a printout of the total counts and an oscilloscope
tracing showing the numbers of particles in
various channels which represent the sizes of
the particles. The sum of particles seen in a
peak channel (each sized particle) can be
compared with any other channel. For
example, if there were 100 particles of a
certain size in one channel and 10 particles of
another size in the second channel, the height
or peak of the first channel would be greater
than the second channel, yielding valuable
differentiation with respect to the size of the
particles in the sample. In this study particles
are equated with bacterial particles after an
appropriate correction is made for background
particles.
These data - total particle counts and
particle size - can be used to interpret the
effectiveness of a germicide against a
bacterial population. An effective germicide
must reduce the numbers of bacteria in
contact with it by inflicting damage on the
bacteria. The particle counter provides this
information. The print out records the total
counts of bacterial particles from the test
samples and provides a basis for determining
whether a reduction in total bacteria occurs.
The oscilloscope tracing shows two facts.
First, it shows the distribution of different sized
particles. Usually a bacterial cell which has
been affected or damaged by a germicide has
a different size than the control culture and
this is seen on the oscilloscope tracing. This
tracing also reflects the total number of
particles in the 50 ml sample by the area
under the combined peaks as well as the
number of particles of each size. The print-out
and the oscilloscope tracing thus yield
information on the reduction of bacterial
population and the damage done to the
bacterial cells - i.e., the effectiveness of the
germicide.
This particle counting and sizing method
gives more information than agar plate counts
because it gives an indication of bacterial
damage as well as reduction of bacterial
populations. In addition, the instrument offers
other advantages. The instrumented method
yields immediate results - one minute after
taking each sample, provides a permanent
record, and is completely objective.
In this study limited parallel plate counts for
viable bacteria demonstrated the close parallel
in results from the two procedures. The
particle counts always exceeded viable
bacterial counts but % reduction of bacterial
populations was very similar using both
procedures. This finding supports the validity
of the particle counter in this type of testing.
The inoculum of Escherichia coli and
Staphylococcus aureus was adjusted to 1 x
106 per ml. The suspending media were
physiological saline (Abbotts injectable) and
phosphate solution (35g. monobasic
potassium phosphate/liter at pH 7.2 diluted
1:800) which were sterilized after filtration
through a 0.22 filter.
The particle count data demonstrated the
effectiveness of the AC-AM Fabric in reducing
the particle (bacterial) count by 90% or more
in 60 minutes, and the change in the particle
size indicated damage to the bacterial cells.
The reduction in viable bacteria was supported
by standard plate count data. At 30 minutes
the reduction of particle counts was 80-86%
for saline, while in phosphate the reduction
was 91-95%. This was also supported by
viable bacteria counts.
Aerosol Test 37
Test swatches were inoculated with an
aerosol of the test bacteria produced in the
Andersen Sampler used for bacterial barrier
efficiency testing. This method provides a
homogeneous distribution of innoculum over
the entire surface of the swatch. Swatches for
0 time exposures were cut septically into small
pieces immediately upon removal from
aerosolization and allowed to drop into the
Letheen Broth. For dwell intervals (1/2 through
3 hours) the inoculated swatches were
transferred to closed humidity chambers, the
humidity of which were maintained at 92%
R.H. at 22 C using a saturated aqueous
solution of Na2HPO4 in the chamber. Upon
termination of a given dwell interval, the
swatch was removed and cut aseptically into
small pieces as described above for elution in
Letheen Broth. The eluting interval in 50 ml.
Letheen Broth was 10 minutes using a shake
speed of 8.5 for the Wrist Action Shaker. The
Letheen Broth eluant was then decanted into a
sterile centrifuge tube (Clay Adams Dynac II)
and centrifuged at 300 r.p.m. for 2 minutes to
separate media linters from the suspension.
One ml. of the supernatant was then cultured.
One ml. of the eluting medium cleared of
media linters was transferred aseptically to a
sterile plate to which was added 18 to 20 ml.
of tryptic soy agar containing 0.7 gm Asolectin
and 5.0 ml.Tween 80/L. Tables X and XI list
results using the above protocol. These tables
show clearly the total control of the test
organisms P. aeruginosa and E. coli within 15
minutes. Considering the dosage level of 1.37
x 106 and 1.3 x 106/swatch respectively,
these results are outstanding.
Adaptation Study (Table XII)
It has been observed in our laboratory that
many traditional leaching types of
antimicrobial agents are susceptible to
inductive or mutative adaptation. Adaptation is
a phenomenon whereby a cell adjusts
enzymatically (inductive) or genetically
(mutational) to a toxicant in its environment. A
study was undertaken with silanequat treated
surfaces to determine the potential for
adaptation of Gram(-) and Gram(+) organisms
after contact exposure. No increase in
adaptive potential was noted after five
successive exposures. This indicates an
extremely low potential for adaptation.
Odor Test (Table XIII)
Many nonwoven fabrics are used where
microbial odors are a significant nuisance. Our
experience with the reduction of microbial
odors on woven fabrics has been through
laboratory and odor panel testing.27 The
extension of this work was done with
nonwovens. Typical diaper constructions were
treated and put in capped jars. Proteus
mirabilis and a small amount of artificial urine
nutrient were added. Ammonia measurements
were taken using Gastec® tubes. Results
show clearly the value of the silanequat
treatment in the reduction of microbial odors.
Scanning Electron Microscopy
(SEM)
Bacterial dilutions were placed on SEM stubs
(experimentals) to check for the correct
bacterial count for electron microscopy using a
light microscope. The experimental stubs were
prepared for electron microscopy by placing a
drop of water containing dilute bacterial
cultures, adding appropriate fibers, incubating
at room temperature, drying under vacuum,
and treating with carbon and gold. SEM
photomicrographs were made using a
Cambridge Scanning Electron Microscope.
Silanequat treated Curex and Sontara were
used in the studies. These experiments
confirmed the antimicrobial action of the
silanequat on E. coli and S. aureus. The
encapsulated bacterium K. pneumoniae was
also tested. The ability of the silanequat to
exert its antimicrobial influence through the
capsule was demonstrated.38 The disruption of
the bacterial cells normal morphology can be
seen below in Figure 2.
FIGURE 2: Before Treatment
FIGURE 2: After Treatment
Clinical Evaluations - In Vivo
Tests in a clinical environment are usually
very complex because of the large number of
uncontrollable variables. Yet, the final link to
improvement in aseptic conditions is to be
found in the clinical environment. Several
studies are currently underway but only two of
these will be reported on here.
Biobarrier Test 39
An AC-AM Fabric instrument wrap was tested
using a modified 28-day Shelf Life Test.
Evaluations were conducted according to the
method described by Schneider.40 The test is
referred to as a Simulated-Storage Evaluation
in which the pathway between naturally
occurring airborne bacteria and a nutrient
media, supportive to their viability and
proliferation, is blocked by the material in test.
Two piles each of AC-AM Fabric Instrument
Wrap, Kimguard, and repellent Sontara (non
silanequat treated) and four piles each 140count muslin (washed) were challenged in this
test. Ten beakers, each containing sterile
broth media that can support a broad class of
microorganisms were covered with sterile
packaging material as described above. The
sterile covered containers were placed upright
on a shelf in a storage room for 28 days to
simulate in-use environmental exposure
conditions. The test containers were not
stressed by pressure from handling or
stacking. Relative humidity ranged from 50%
to 80%. The storage room was similar to a
hospital storage room (in which sterile material
is kept) in size, shelves, and placement of
material on shelves. Traffic into the storage
room was not heavy, but was entered several
times daily during the work week to remove or
replace storage items. A failure was identified
by visual observation of microbial growth as
evidenced by turbidity. Confirmation of growth
and organism types, or no growth, was done
by slide preparation and subsequently
determined by microscopic examination.
The results are tabulated in Table XIV.
Several conclusions can be drawn from the
data:
1.
Linen afforded poor biobarrier protection
as 60% of the containers showed growth
during the test interval.
2.
Kimguard afforded good protection as
90% of the test containers were negative.
3.
AC-AM Fabric afforded the best
protection. There were no failures.
4.
Repellent Sontara (non silanequat
treated) performed poorly as 50% of the
test containers were contaminated.
The above data support the conclusion that
the antimicrobial constituent in the AC-AM
Fabric provides a substantial improvement in
biobarrier activity over 140-count linen and
Sontara. The interpretation of the SimulatedStorage Evaluation Test is direct. It is highly
sensitive to detection of microbial penetration
of the biobarrier by a broad class of
microorganisms due to the moist environment
and nutrient on the sterile side of the fabric.
Since all classes of test material are exposed
to identical test conditions, the observed
differential penetration is a meaningful
representation of the relative biobarrier of the
four materials challenged. In this test, AC-AM
Fabric Instrument Wrap had an equal chance
of penetration by microbes, yet it provided an
excellent biobarrier against contamination by
environmental organisms.
Although these data were generated for
CSR and instrument wraps interpolation to a
variety of nonwovens and nonwoven
environments is possible.
AC-AM Surgical Drape
Reinforcement Study
Surgical Protocol: A double-blind study was
conducted of 98 surgical cases using a
reinforced laparotomy drape. The drape
reinforcement was modified to consist of four
sections (A,B,C, and D). Although all sections
appeared to be identical, only two of the four
were made of AC-AM Fabric. The location of
the AC-AM Fabric sections were randomly
varied. The surgical cases included clean,
clean contaminated and contaminated cases.
Laboratory Protocol: After each procedure,
viable bacteria from a portion of the AC-AM
Fabric and non-treated reinforcement sections
were removed. These swatches were agitated
in a bacterial recovery solution and passed
through a micro-porous filter. The filters were
then placed on a pad containing nutrient
media and incubated for 72 hours.
Clinical Results: Of the 98 surgical cases
studied, this in-vivo study demonstrated that
AC-AM Fabric reduces the number of viable
potential pathogens in the critical areas by
over 81%.
Comments from the study monitor include:
"I would like to bring you up to date on the
clinical project I have been involved in using
the AC-AM Fabric surgical drape. The doubleblind technique was used with random
distribution of AC-AM Fabric and non-AC-AM
Fabric strips on top of the surgical drape. Our
early observations indicate a dramatic
reduction in the bacterial colony count on the
AC-AM Fabric versus the non-AC-AM Fabric
strips. This held true with clean, clean
contaminated, and contaminated surgical
procedures of varying lengths of time. This
data in the operating room certainly appears to
verify the laboratory data done by American
Convertors prior to release of the drapes for
general use. The eduction in the number of
bacterial colonies on the drape should
contribute to a decreasing number of viable
bacteria capable of infection. In addition, the
mechanical usage of the drape has also been
very satisfactory. The reinforced area in the
AC-AM Fabric portion prevents strikethrough.
The drape is soft and pliable enough to mold
to the configuration of the patient. The surface
also seems to prevent slippage of
instruments." This study is still ongoing and
will be the subject of a future publication.
Summary
The evolution of medical fabrics
from the first tier usage of linen
drapes to the second tier of barrier
and absorptive nonwovens has
guided the way to the third tier
nonwoven draping material - a safe,
active nonwoven. This third tier
nonwoven provides clearly
demonstrable efficacy against a
variety of laboratory and clinical
(environmental) microorganisms.
The microbiological test techniques
used to demonstrate this
effectiveness, as reported herein,
are extremely varied. Results
published here confirm the
effectiveness of ISO-BAC Fabric
under simulated and "real world"
conditions. While we are still
learning about the mechanism and
performance of the ISO-BAC, we
have confirmed that: (1) major
levels of contamination are present
at the surgical wound site in the
area of the reinforcement around
the fenestration, and (2) ISO-BAC
(treated with the ÆGIS Microbe
Shield) is capable of significantly
reducing this level of contamination.
Copyright © 2000, ÆGIS Environments, All rights reserved
Form 5b Rev 09/2002
TM
LITERATURE CITED
1. Majno, G., “The Healing Hand,” Harvard University Press, 1975, p. 54.
2. Ibid p. 183.
3. Ibid p. 188.
4. Neuber, G. and Hunter, Robb, AORN Journal Vol. 24., No. 1, July 1976, p. 54-55.
5. Laufman, H., Bulletin of N.Y. Academy of Medicine, Vol. 54, No. 5, May 1978.
6. Beck, W. C., American J. of Surgery, Vol. LXXXIII, No. 2, Feb., 1952, p. 125-126.
7. Beck, W. C., AORN Journal, Vol. 27, No. 7, June, 1978, p. 1273-1274.
8. Sweeney, W. J. III, Obstetrics and Gynecology, Vol. 24, No. 4, Oct. 1964, p. 609, 612.
9. Dineen, Peter, Clinical Orthopedics and Related Research, p. 210.
10. Ibid p. 212.
11. Alford, D. J. et al, American J. of Surgery, Vol. 125, May 1973, p. 589-591.
12. Charnley J. and N. Eftekhar, Modern Medicine, May 19, 1969, p. 200.
13. Ha'Eri, G. B. and A. M. Wiley, Clinical Orth. and Related Res., A.M. No. 154, Jan-Feb, 1981.
14. Whyte, W. et al., Brist. J. of Surgery, Vol. 65, 1978, p. 469.
15. Hamilton, H. W., et.al., Clinical Orth. and Related Res., No. 141, June, 1979, p. 243-245.
16. Moylan, J. et al., Surgical Forum, Vol. 25, November, 1975, p. 733.
17. Moylan, J. et al., Surgery, Gynecology, and Obstetrics, Vol. 151, No. 4, Oct. 1980, pp. 466, 467, 470
18. Hartman, Janet, “Disposable Drapes: One Team's Experience,” Gillette Children's Hospital.
19. Laufman, Harold, et al., Ann. Surgery, January, 1979, p. 72 and 74.
20. Schwartz, J. E. and D.E. Saunders, et.al., Surgery, Gynecology, and Obstetrics, Vol. 150, April, 1980, p. 507-512.
21. Davidson et.al., Brit. J. of Surgery, Vol. 58, No. 5, May 1971, p. 333-337.
22. AORN Journal, Vol. 21, No. 4, March, 1975, p. 594.
23. ISO•BAC Surgical Drape Reinforcement - a product of American Convertors.
24. ISO•BAC Instrument Wrap - a product of American Convertors.
25. Altemeier and Culbertson, 2/14/70, Vol. 102, p. 251-253.
26. Ibid Citation 21.
27. Gettings, Richard and B. Triplett, AATCC Book of Papers, 1978, p. 259.
28. Malek, James R. and J. L. Speier, J. Coated Fabrics, 12, 1982, p. 38.
29. Speier, J. L. and J. R. Malek, J. of Colloid and Interface Science, Vol. 89, #1, Sept. 1982, p. 68.
30. American Association of Textile Chemists and Colorists - 30 Parallel Streak Test.
31. American Association of Textile Chemists and Colorists - 100 Substrate Padding Test, Dow Corning
Corporate Test Method 0829.
32. Dow Corning Corporation, Corporate Test Method 0923, Dynamic Shake Flask Test.
33. American Convertors - ISO•BAC™ Literature, August 1980.
34. Report to American Convertors - July 28, 1980 from Acta Laboratories, Inc., Highland Park, IL.
35. Faber, W. U., B. Wille and S. Wirth. Examination of Bacteria Kinetics in the Artificial Contamination of Various O.R. Drapes.
Hygiene and Infection Control.
36. Report to American Convertors - April 9, 1982, from Bacti-Consult Assoc., Houston, Texas.
37. Report to American Convertors - June 30, 1980 from Acta Laboratories, Inc., Highland Park, IL.
38. Report to American Convertors – April, 1981 from Walter C. McCrone Institute, Inc.
Institute for Hospital
39. Report to American Convertors - August, 1981 from Bacti-Consult Assoc., Houston, Texas.
40. Schneider, Philip M., Microbiological Evaluation of Package and Packaging - Materials Integrity. Medical Device and Diagnostic Industry; May, 1980;
pp. 29-37.
TABLE I
Results
Minimum Inhibitory Concentration Test
Dow Corning 5700 Antimicrobial Agent
Test Organism
MIC (Fg/ml)
Streptococcus Faecalis
Gram (+) Bacteria
10
Escherichia coli
Gram (-) Bacteria
100
Pseudomonas aeruginosa
Gram (-) Bacteria
100
Aspergillus niger
Fungus
1000
TABLE II
Results
American Association of Textile Chemists and Colorists
Method 30, Fungicides, Evaluation on Textiles
Dow Corning 5700™ Antimicrobial Agent Treated Nonwovens
Percent of Sample Covered1 After:
Sample
3 Days
5 Days
7 Days
Untreated
20
60
100
Treated Level A
0
5
20
Treated Level C
0
0
0
1 Aspergillus niger
TABLE III
Results
American Association of Textile Chemists and Colorists
Method 100, Antimicrobials on Fabrics1
Dow Corning 5700 Antimicrobial Agent Treated Nonwovens
Sample
Microorganisms
Percent Reduction
Control
Staphylococcus aureus
16
Treated2
Gram (+) Bacteria
100
Control
Treated
Escherichia coli
Gram (-) Bacteria
0
99.6
Control
Treated
Klebsiella pneumoniae
Gram (-) Bacteria
0
100
Control
Treated
Saccharomyces cerevisiae
Yeast
0
99.9
1 DuPont FC-170 surfactant used, substituted for Rohm and Haas Triton X-100
2 Fabric was Kaycel
TABLE IV
Results
Clinical Isolate Control2
AEM 5700 Antimicrobial Treated Nonwovens
Sample
Microorganism
Percent Reduction
Untreated1
Treated
Inoculum
Citerobacter diversus
Wound Isolate
Untreated
Treated
Inoculum
Pseudomonas aeruginosa
Urine Isolate
28.3
99.9
0
Untreated
Treated
Inoculum
Staphylococcus aureau
Wound Isolate
0
99.7
0
Untreated
Treated
Inoculum
Escherichia coli
Urine Isolate
11.6
98.6
0
Untreated
Proteus mirabilis
0
14.3
93.6
0
Treated
Inoculum
Wound Isolate
99.5
0
1 Sontara Fabric
2 Dow Corning CTM 0923
TABLE V
Results
Fluid Compatibility Tests
AEM 5700 Antimicrobial Treated ISO-BAC Fabric
Percent Reduction1 with 15 Min. Contact
Sample
Buffered Phosphate
Saline
Serum
Untreated Linen
8
0
0
Untreated Sontara
Nonwoven
0
0
0
Treated Sontara
99+
90+
90+
1 Modified AATCC method 100 using test fluids Klebsiella pneumonia statistically significant at the
95% confidence level.
TABLE VI
Results
Surface Testing of Whole Blood and Bacteria1
Contact Time
(Minutes
# of Organisms
Per Ml
% Reduction
A) Green Surgical Linen
0
1
3
5
30
60
120
6,550
4,750
3,750
400
200
200
100
27
43
94
97
97
98
B) Non-WovenTablecover
From J&J Laparotomy Pack
0
1
3
5
30
60
120
22,100
20,800
15,300
2,800
550
700
200
6
31
87
98
97
99
Sample (Surface)
C) HiLoft Untreated Control
0
1
3
5
30
60
120
10,450
8,650
8,900
200
0
0
0
17
15
98
100
100
100
D) HiLoft with AEM 5700 Antimicrobial - ISO!BAC Fabric
0
1
3
5
30
60
120
12,500
5,000
5,700
0
0
0
0
60
54
100
100
100
100
1 Inoculum: 90% Whole Fresh Rabbit Blood Contaminated with Klebsiella pneumoniae ATCC 4352
TABLE VII
Results
Comparison of Contaminated Whole Blood Versus
Defibrinated Blood in Solution and on Line
# of Organisms Per Ml:
Test Method
A) Solution Test
(Organism Added to
Blood)1
Contact Time
(Minutes)
0
1
2
3
5
30
120
360
Whole Blood
30,000
30,000
30,000
2,990
309
2
-
Defibrinated Blood
14,726
15,375
14,650
13,900
14,275
15,125
14,625
13,375
B) Surface Test (Contaminated
Blood Added to Linen
Swatches)2
0
1
2
3
5
30
60
120
180
6,550
4,750
5,600
3.750
400
200
200
100
100
1 Retrievals from the solutions.
2 Modified AATCC-100 Padding Test, Klebsiella pneumoniae preinoculated into test fluids.
8,750
9,300
9,000
8,700
8,850
9,900
10,350
10,850
7.650
TABLE VIII
Results
Surface Testing of Defibrinated Blood and Bacteria1
Contact Time
(Minutes)
# of Organisms
Per Ml
% Reduction
A) Green Surgical Linen
0
1
3
5
30
60
120
8,750
9,300
8,700
8,850
9,900
10,350
10,850
0
0
0
0
0
0
B) Non-Woven Tablecover From
J&J Laparotomy Pack
0
1
3
5
30
60
120
14,050
17,450
13,750
13,400
15,350
16,450
17,800
0
2
5
0
0
0
C) HiLoft Untreated Control
0
1
3
5
30
60
120
13,650
14,150
13,600
14,000
13,750
14,600
16,850
0
0
0
0
0
0
D) HiLoft with AEM 5700 Antimicrobial - ISO!BAC Fabric
0
1
3
5
30
60
120
14,900
15,400
14,400
12,400
6,050
5,650
4,200
0
3
17
59
62
72
Sample (Surface)
1
Inoculum: 90% Whole Fresh Rabbit Blood Contaminated with Klebsiella pneumoniae ATCC 4352
TABLE IX
Results
Preliminary Tests Comparing the Reduction in Count
of Staphylococcus epidermidis Applied to HiLoft ISO!BAC
Compared to Untreated Control
Bacteria
Suspended in
Count/0.1 ml
(x106)
Swatch
Wetted
Repl.
Count/ml (X103)
Control
Treated
Percent
Reduction
Clark-Lubs
KH2PO4
1.46
Clark-Lubs
1
2
198
201
0
0
100
100
Acta Sweat
1.48
Acta Sweat
1
209
0
100
2
214
0
100
TABLE X
Results - Aerosol Test
ISO!BAC Control of Pseudomonas aeruginosa in Saline1
Count/ml (X103 at Each Dwell Interval)
Media No.
Repl.
0
1/4 hour
½ hour
1 hour
2 hour
3 hour
Control2
1
2
3
Av.
114
115
98
109
120
101
116
112
102
91
116
103
136
107
110
118
122
112
92
109
126
114
121
120
ISO!BAC
Level A
1
2
3
Av.
11
16
19
15
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
ISO!BAC
Level B
1
2
3
Av.
14
12
15
14
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1 Initial population in broth 98 x 107/ml. Diluted 1:100 in saline and delivered 0.14 ml as an aerosol via
Harvard Infusion Pump. Population deposited on swatch 1.37 x 106 cells/ml
2 Whatman No. 40 filter paper
TABLE XI
Results
Aerosol Test
ISO!BAC Control of Escherichia coli in Saline1
Count/ml (X103 at Each Dwell Interval)
Media No.
Repl.
0
1/4 hour
½ hour
1 hour
2 hour
3 hour
Control2
1
2
3
Av.
136
114
122
124
110
119
140
123
103
92
112
102
115
122
108
115
108
102
124
111
123
107
98
109
ISO!BAC
Level A
1
2
3
Av.
14
22
19
18
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
ISO!BAC
Level B
1
2
3
Av.
23
16
18
22
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1 Initial population in broth 131 x 106 cells/ml. Diluted 1:20 in saline and delivered 0.2 ml as an aerosol via Harvard
Infusion Pump. 1.3 x 106 cells deposited on swatch.
2 Whatman No. 40 filter paper.
TABLE XII
Results
Bacterial Adaptation Studies
AEM 5700 Antimicrobial Agent Treated Fabrics
Percent Reduction1
Klebsiella pneumoniae
Staphylococcus aureus
Exposure2
1
2
3
4
5
1
2
3
4
5
Control
0
0
0
0
0
10
5
9
13
26
Treated
99+
99+
99
98
99+
99
98
96
99
99
1 Dow Corning CTM 0923 Shake Flask Test
2 Shake Flask Survivors were used for subsequent exposures
TABLE XIII
Results
ISO!BAC Nonwoven Fabric1
Total Accumulated Ammonia (PPM) Produced
After:
Sample
2 hours
4 hours
6 hours
8 hours
Untreated
0
0.5
5.5
5.5
Treated
Level A
0
0
2
28
Treated
Level B
0
0
0.5
3.5
1 Test Organism: Proteus mirabilis (Clinical)
Inoculum: 1,000,000 CFU/ml
TABLE XIV
Results - ISO!BAC
Shelf Life Simulated-Storage Evaluation1
Bottom
Shelf
Jar
ISO!BAC
(2 ply)
Linen
(140 Count, 4
Ply)
Sontara
(2 Ply)
Kimguard
(2 Ply)
1
2
3
-
+
+
-
-
-
4
5
6
7
(Cornyebacterium sp
only)2
+
+
+
+
+
+
8
9
10
-
+
+
-
+
+
-
-
Middle
Shelf
Top
Shelf
1 Method described by Schneider
2 Not a valid contaminant as noted by investigator.
+ = Microbial growth (variations of mold, yeast, Gram-positive, and Gram-negative microorganisms).
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Pavedry fabrics help eliminate common causes of expensive pavement breakup in
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and the new asphalt layer produces an effective moisture barrier, protecting the sub-base from deterio
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High Strength
Tubes
Monofilament (drainage)
Asphalt Overlay
Road Repair
Erosion Control
Introduction
Biodegradable Coir
Permanent TRM
High Performance TRM
Photodegradable
Silt Fence
Drainage/ Subsurface
Paving
Introduction
Print this page
VersiCell
VersiDrain 8
VersiDrain 8 Mesh
VersiDrain 10 Geo
TurfPave Grass Pavers
Pave-Dry
Geotextile for asphalt overlay and road construction. It is a nonwoven needlepunc
staple fiber geotextile specifically engineered for asphalt overlays. Pave-Dry fabri
the old and new asphalt layers in flexible pavement systems.
Because polypropylene has an affinity for petroleum products, there is a considera
coat into the yarns. This creates an inert, laminated monolithic composite that has
resurfacing years Pave-Dry nonwoven paving fabrics increase the pavement life lo
repaving techniques of new asphalt overlays.
Long-term field evaluations have shown that the proper use of paving fabrics in a
pavements increased pavement life up to 50%. Therefore, using Pave-Dry fabrics
projects will reduce maintenance costs and allow for improved effectiveness of yo
management system. Since studies state that paving fabrics provide the performan
of AC thickness, Pave-Dry geotextiles are the most economical interlayer option.
Most subgrade failures occur from surface water entering the pavement’s base cou
foundation soil’s shear strength. Pave-Dry geotextiles absorb tack coat sprayed on
pavement to create a permanent moisture barrier. This system prevents water from
joints, and the porous pavement itself while enhancing surface drainage. By diver
subgrade maintains a lower moisture content and its maximum bearing capacity. W
bonded to the original pavement, surface deflections, excessive cracking and poth
prematurely the overlay.
Pave-Dry geotextiles also function to retard reflective cracking. By unrolling Pave
surface, the ductility and shear resistance of the entire flexible pavement system is
energy normally transferred from cracks in the old pavement into the overlay is ab
interlayer. Furthermore, the ability of the wearing course to resist tensile stress on
increased.
Installation Guidelines
Surface Preparation. Clean the old pavement of dust, dirt, vegetation, and moistur
mm should be cleaned and filled with a suitable crack sealant. Potholes should be
course, filled and treated with tack coat.
Tack Coat Application. The amount of tack coat required to saturate Pave-Dry ge
1.1 L/m². The actual rate of application depends upon the relative porosity of the o
temperature and tack coat. The specified tack rate should be applied by a distribut
uniform manner at a temperature below 1490 C. It should be sprayed approximate
width of the paving fabric. If asphaltic emulsions are used, the tack coat must ade
placement.
Installation of Paving Fabric Pave-Dry. Geotextiles should be placed with the cale
tack coat is still warm and tacky to assure the best bond and absorption possible. I
manually or with fabric installation units (available from manufacturers nationwid
light and the vehicle should be driven as straight as possible to assure a smooth an
installation. A lightweight metal tube should be inserted inside the geotextile core
Hand-broom all small wrinkles. Wrinkles larger than 12.7 mm must be carefully s
overlapped in the direction of paving. Additional tack coat must be applied betwe
must be overlapped at least 75 mm along roll edges and 15 cm at roll ends.
Paving Operation. If a Pave-Dry geotextile becomes wet during installation, it mu
completely before paving. Wet fabric should not be opened to traffic. A wet fabric
laminated, composite system required. No vehicular traffic is recommended on th
Standard paving operations should follow. 38 mm of asphalt is recommended as a
Chip Seal Application. After the Pave-Dry geotextile has been properly deployed
surface should be coated with the type and amount of asphaltic spray used in conv
applications (Alternatively, excess tack coat can be applied under the fabric). The
the type and size of stone chips. Chips should be spread uniformly and equipment
directly on the saturated fabric. The surface is then compacted with steel drum and
the excess stone is swept away.
Geotextile
Applications
Overview
Subgrade-Roadbase
Improvement
Pavement
Enhancement
Subsurface
Drainage
Erosion Control
Walls & Slopes
Containments
Silt Fence &
Landscape
Railroad
Amoco Fabrics &
Fibers Co.
Civil Engineering
Fabrics
260 The Bluffs
Austell, Georgia
30168
PH:800/4457732(SPEC)
Fax:770/944-4584
email:
geotextiles@bp.com
web: geotextiles
homepage
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Areas of Application
Design Challenges
Benefits
Recommended Products-AASHTO M 288 00
SuperGro - Erosion Control/Vegetative Growth
Areas of Application
Geotextiles have replaced graded granular filters used beneath riprap or other armor
materials. Typical applications include drainage channels, shorelines, river, coastal
protection, canals, and bridge and pier scour protection systems.
Design Challenges
The effective control of destructive erosion in shorelines, riverbanks, drainage ditche
canals has always posed a difficult problem. This stems from the need for a robust ou
protective layer to absorb the energy of wave or current, and an inner protective laye
traditionally in the form of an aggregate filter to prevent erosion of the bank soil. Thi
layer has a particularly difficult role to play, since it must fill the often conflicting
requirements of being fine enough to act as a bank soil filter, yet coarse enough to pr
generation of high differential pressure between the bank and external water levels. T
problems are overcome with properly designed geotextile filter fabric installed to cov
exposed surface of the bank. The selection of geotextiles used in shoreline erosion co
requires consideration of filtration mechanisms, installation stresses, and long-term d
requirements. Filtration mechanisms will rely on the gradation of the soil, pore size
characteristics of the geotextile, and water flow conditions. While design criteria hav
well established for geotextile filters, the special nature of erosion control application
be carefully considered in selecting the most appropriate geotextile for the specific si
conditions. The design relations are complicated by the reversing flow conditions tha
coastal erosion control applications.
Benefits
Compared to conventional graded granular soil filters, geotextiles offer advantages b
providing:
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consistent and continuous filter
reduced environmental impact
simplified, higher quality construction
reduced time of construction
a substantial reduction in material costs
Recommended Products - AASHTO M288-00
Fabrics and Fibers has a broad spectrum of nonwoven and woven geotextiles specific
designed for erosion control applications. Our ProPex product line enables you to cho
geotextile that precisely meets your project conditions and the AASHTO M 288-00
specification. Because the product you need will vary with construction conditions, y
local distributor or Fabrics and Fibers technical engineers can assist you in selecting
Propex geotextile that is appropriate for your job.
Erosion Control Geotextile Requirements- AASHTO M 288 00
Product Line
Class 1
Class 2
Class 2
Style
Pass to 200 sieve=>
ProPex
4551
<15%
15
15
15
to >50% <15% to >50% <15% to
50%
50%
50%
*
*
*
>50%
Nonowoven 4552
Geotextiles 4553
4510
4512
4516
p
*
*
*
*
p
*
*
*
*
p
*
*
*
*
1198
*
1199
ProPex
Woven
2016 *
Geotextiles 2019
p
2044
*= meets AASHTO default requirements
p= provisionally meets AASHTO
requirements, subject to engineer approval
*
p
SuperGro (Style 4868): is used when vegetative growth is all that is required for ero
control. SuperGro is a fibrous matrix blanket that control soil sediment runoff while
to establish vegetative growth.
For additional and support information: Case Histories, Technical Resources, and
Literature.
 American Assoc. of State Highways and Transportation Officials (AASHTO)
 American Society of Testing and Materials (ASTM)
 International Erosion Control Association (IECA)
 Geosynthetic Materials Association (GMA)
ANNUAL REPORT OF COOPERATIVE REGIONAL
PROJECT S-272
Supported by Allotments of the Regional Research Hatch Act, as Amended August
11, 1955
January 1 to December 31, 1999
PROJECT: Development and Assessment of Innovative Textile Materials for
Environmental Compatibility and Human Health and Safety
COOPERATING AGENCIES AND PRINCIPAL LEADERS:
1. Arkansas (AR) University of Arkansas, Fayetteville, M.M. Warnock*
2. Alabama (AL) Auburn University, Auburn, B.L. Slaten*
3. Florida (FL) Florida State University, Tallahassee, R.M. Cloud*, K. Grise, and
M.A. Moore
4. Georgia (GA) University of Georgia, Athens, K. Leonas*
5. Indiana (IN) Purdue University, Lafayette, C.M. Ladisch*
6. Kansas (KS) Kansas State University, Manhattan, B.M. Gatewood* and G. N.
Ramaswamy
7. Kentucky (KY) University of Kentucky, Lexington, E.P. Easter*
8. Tennessee (TN) University of Tennessee, Knoxville, L.C. Wadsworth*, and B.J.
Collier
9. Louisiana (LA) Southern University, Baton Rouge, G. Wasike*
10. Louisiana (LA) Louisiana State University, Baton Rouge, Y. Chen and I.
Negulescu*
11. Mississippi (MS) Mississippi State University, Starkville, C. Boyd*
12. Nebraska (NE) University of Nebraska, Lincoln, P. Crews* and L.E. Scheyer
13. North Carolina (NC) University of North Carolina, Greensboro, C.J. Kim*
14. Wisconsin (WI) University of Wisconsin, Madison, A.M. Sarmadi*
USDA-ARS, SRRC, N.R. Bertoniere
USDA-CSREES, S.P. Welch
S-272 Administrative Advisor : B. Brown
PROGRESS OF WORK AND PRINCIPAL ACCOMPLISHMENTS:
Objective 1: To develop and characterize innovative textile and related materials
from natural and synthetic polymers with an emphasis on agricultural fibers and
by-products.
Many newer products were created and tested for performance. A joint project resulted in
a nonwoven blanket produced from cotton and recycled polyester. The experimental
blanket was comparable to commercial nonwoven blankets in comfort, quality, and
thermal covering. Polymers from waste were recovered and recycled into thermoplastic
composites for food packaging, wound dressings and hygiene products. Cotton and glass
fabrics were grafted with linking compounds and TiO2 and evaluated for their ability to
destroy low concentrations of gaseous organic compounds in the presence of UV light.
The treated glass fabrics may have application in removing air borne organic
contaminates. Wheat gluten was modified with methyl acrylate, sodium hydroxide, and
ethanol and characterized by dye binding techniques and NMR and the films made were
evaluated for performance properties.
Alpha-chymotrypsin was successfully deposited on RF-plasma treated PET, PP and PS
substrates. Computer-aided conformational modeling was used to study the mobility of
the enzyme. Stability of the enzyme was good and it retained it’s activity even after
several washing/assay cycles. A nonwoven fabric with a cotton surface was developed
with increased resistance to pilling and linting. This fabric was tested for fabric hand and
comfort in a wear study conducted in an environmental chamber.
Fabric softeners developed by Albemarle were evaluated on cotton and 50/50
cotton/polyester using the new data acquisition system for the Kawabata instruments. The
most important fabric properties were shear rigidity and shear hysteresis. Attempts were
made to improve the softness and wrinkle resistance of kenaf/cotton fabrics using
softeners, formaldehyde, low formaldehyde and non-formaldehyde resins. Experimental
kenaf/cotton fabrics in shirt weight were developed for apparel.
A research grant (LEQSF) from the Louisiana Board of Regents was obtained by LSU
scientists to install a narrow weaving machine (Jacob Muller NF42 2/130). This allowed
the processing of non-conventional fibers, such as sugar cane rind, kenaf, ramie, and flax,
into yarns and fabrics. Bagasse treated- with caustic, water etc., was evaluated for
possible use as a yarn forming fiber source. Fibers were stiff and further modifications of
the processes is being researched.
Dyeuptake and colorfastness studies on polylactic acid (PLA) fabrics suggested that
small linear dyes provided good color, however, anthraquinone dyes and other dyes with
carbonyl groups should be avoided. Washfastness, lightfastness and resistance to fume
fading was acceptable.
The dyeability of polypropylene (PP) and polyethylene terephthallate (PET) with waterbased dyes was enhanced by treating them with near atmospheric plasma treatment.
The formulation for print paste with soybean alkyd binders are still being optimized to
obtain the best color, softness and colorfastness. The bleaching procedure for wheat straw
was optimized to obtain a bright, creamy white color that will be used to increase the
value of strawboards. The performance of bleached straw boards was compared with
regular wood particle board. High resin composites (bioplastics) with wheat straw were
successfully made for injection molded products. Cellulose was extracted, purified and
characterized for use in various products.
Starch (both native and treated) were characterized by ESCA, FTIR, and SEM and
grafted using the plasma treatment for applications in biodegradable plastics. Results
showed that plasma treatment was successful in functionalizing the surface of starch.
Objective 2: To assess the environmental compatibility of selected and newly
developed processes, materials, and products from fibers of polymeric and
agricultural origin.
The soil burial study has been continued to include outside burial. The previous study
related to biodegradation in compartmentalized trays housed within a constant
temperature chamber. For this new study, cotton, rayon,Tencel, kenaf , hemp and cotton
canvas and hemp and cotton
denim have been included in the outside burial study. End result will be a comparative
analysis of biodegradation properties for fabrics buried outside and in the constant
temperature room.
The fungal and termite resistance of wheat, barley, and oat straw fiber, and kenaf, corn
husk, sugar cane baggase, and soybean hulls were evaluated in both no-choice and choice
feeding tests.
Objective 3: To evaluate the functional performance, consumer acceptance, and
potential commercialization of textile materials for human health and safety and/or
value added products.
Since cotton is competing with microdenier polyester fabrics, a database for the
properties of microdenier polyester fabrics was developed. The effect of silicone finishes
on aesthetics and hand of the fabrics were studied. The correlation between instrument
measurements of hand and actual subjective ratings were also determined. Nonwoven
fabrics, produced by Tennessee, containing cotton fibers on the surface were evaluated
for hand related properties using a ring friction apparatus which is capable of
distinguishing small differences in fabric hand.
To determine consumer acceptance and market analysis of non-coventional textile fibers
in value-added products, a national survey was conducted. The preliminary results
indicated that the respondents: were unfamiliar with non-traditional fibers such as kenaf,
hemp, and jute;
did not feel that textiles contributed significantly to environmental pollution; and
biodegradability was not a factor influencing their purchasing decisions. National study
will be path-analyzed using LISREL.
Two nonwoven fabrics commonly used in surgical gowns and drapes were treated in a
one-bath application with a fluorochemical and antimicrobial finish. The application was
found to be successful and adequate repellency and antimicrobial activity were achieved.
Two plain woven fabrics commonly used in hospital bedding (sheets) were treated in a
one-bath application with a durable press and antimicrobial finish. The durable press
property of treated fabrics after 50 launderings was satisfactory but antimicrobial activity
was not apparent after the launderings.
Cotton, kenaf and a 50/50 cotton/kenaf blend fabrics/yarns were examined for differences
in zeta potential using direct dye solutions. Zeta potential was dependent on fiber makeup.
A study examining the influence of fiber type, thickness, thread count, and porosity on
UVR transmission was conducted. Results showed that fabric porosity was the single best
predictor of an undyed woven fabric's UVR-blocking properties. A detailed study on the
influence of chemical constitution of dyes on the extent of UV protection was evaluated
using cotton and cotton/polyester fabrics.
USEFULNESS OF FINDINGS:
Many innovative products and techniques are being created that will impact the quality of
life. As process economics are considered and product properties determined, end use
markets will be developed. Assessment of the environmental impact of processing and
use of current value-added textile products, being investigated in this project, will yield
benefits as well.
Protective clothing that provides the necessary safety margin along with an acceptable
comfort level is an important effort. Methods for evaluating comfort and safety of new
and modified
textile products are being developed to help producers and consumers. Consumer
perceptions and market potential of these fabrics are being determined. Use of cotton in
nonwoven products will considerably improve their comfort properties. Provision of
information on selection of clothing for maximum protection from UV radiation will also
help consumers.
This research project has proven the potential to produce low- cost nonwoven products
using recycled synthetic fibers. This research provided industry with a new technique of
objective evaluation for fabric softeners. The acquisition of narrow gauge loom not only
enhanced the Louisiana agricultural economy, but also benefited the ongoing regional
research project.
WORK PLANNED FOR NEXT YEAR:
The focus of the research during the next year will be to finalize the optimization of all
conditions for producing products and processes that enhance the quality of life.
Development and evaluation of newer cotton nonwovens, kenaf, sugar cane textiles,
wheat straw composites, grafted starch for biodegradable plastics will continue, with
pooling of resources from the participating stations to more effectively characterize and
test the performance of these products. Gathering and analysis of subjective data on
fabric comfort and safety and on consumer perceptions of new products will be
completed.
PUBLICATIONS DURING THE YEAR:
Journal Articles:
Bel-Berger, P., Boylston, E.K., Kimmel, L., Vonhoven, T., and Ramaswamy, G.N.,
“Cotton/Kenaf Fabrics: A Viable Natural Fabric:, Journal of Cotton Science, 1999, 3(2),
pp. 60-70.
Chen, Y., Collier, B. J., and Collier, J. R., Application of Cluster Analysis to Fabric
Classification, Intemational Journal of Clothing Science and Technology, in press.
Chen, Y., Kampen, W., and Collier, B. J., Evaluation of CPI Starch for Laundry
Applications, Textile Chemist and Colorist, 1998, 30(11), 25-30.
Chen, Y., Kampen, W., Neguiescu, I., Despa, S., and Collier, B. J., Evaluation of CPI
Starch for Warp Sizing Application, Textile Chemist and Colorist, 1999, 31 (1), 25-28.
Choi, S.C., Kim, S., & Kim, C.J. (1998). Effects of fiber fineness and silicone treatment
on hand of
polyester knitted fabrics I: Mechanical properties. Journal of the Korean Fiber Society.
[in press]
Choi, S.C., Kim, S., & Kim, C.J. (1999). Effects of fiber fineness and silicone treatment
on hand of polyester knitted fabrics II: Finishing effect. Journal of the Korean Fiber
Society. [in press]
Ganapathy, R., Manolache, S., Sarmadi, M., Simonick W.J. and Denes, F.,
'Immobilization of Active alpha-Chymotrypsin on RF-Plasma Functionalized Polymer
Surfaces. J. of Applied Polymer Science. (in Press)
Gatewood, B.M., Wu, J., Lumley, A.C., and Lewis, A.M., “Dyeing Behavior of Wheat
Straw- A Nonconventional Lignocellulosic Fiber,” Textile Chemist and Colorist, April
1998, 30(4), pp. 38-44
Hamilton (Scheyer), Lois E., and Annacleta Chiweshe. The Performance of Pigment
Print Paste Binders Prepared by Modifying Wheat Gluten with Methyl Acrylate,
Starch/Starke , 1998, 50, pp. 213-218.
Huang, W. and Leonas, K.K. "One-Bath application of Repellent and Antimicrobial
Finishes to Nonwoven Surgical Gown and Patient Drape Fabrics". Textile Chemist and
Colorist, March 1999, 31(3), pp. 11-16.
J. 0. Kim and B. Lewis Slaten. Objective Evaluation of Fabric Hand. Part I:Relationships
of Fabric Hand by Extraction Method and Related Physical and Surface Properties.
Textile Research Journal, January 1999, 69(l), pp. 59-67,
Leonas, K.K. "Effect of Laundering on the Barrier Properties of Reusable Surgical
Gowns' American Journal of Infection Control, October 1998, 26(5), pp. 495-501.
Leonas, K.K. and Huang, W. "Transmission of Small particles Through Selected Surgical
Gown Fabrics, International Nonwovens Journal, Spring 1999, 8(I ), pp 18-23.
Lumley, A.C., and Gatewood, B.M., “Effectiveness of Selected Laundry Disks in
Removing Soil and Stains from Cotton and PET,” Textile Chemist and Colorist, Dec.
1998, 30(12), pp. 31-35
Neguiescu, 1. I., Despa, S., Chen, J. (Y.), Collier, B. J., Despa, M., Denes, A., Sarmadi,
M., and Denes, F. S., Characterization of Polyester Fabrics Treated in Electrical
Discharges of Radio-Frequency Plasma, Textile Research Journal, 2000, 70(1)
Neguiescu, 1. I., Kwon, H., Collier, B. J., Collier, J. R., and Pendse, Ajit., Recycling
Cotton from Cotton/Polyester Fabrics, Textile Chemist and Colorist, 1998, 30(6), pp. 3135.
(Selected as best paper published in Textile Chemist and Colorist for 1998)
Negulescu, 1. I., Kwon, H., and Collier, B. J., Determining Fiber Content of Blended
Textiles, Textile Chemist and Colorist, 1998, 30(6), pp. 21-25.
Patricia Crews, S. Kachman, and Andrea Beyer, "Influences of UVR Transmission of
Undyed Woven Fabrics," Textile Chemist and Colorist, June 1999, 31(6), pp.17-26.
Ramaswamy, G.N., B. Soeharto, and J.Wang, “Mercerization of Dyeing of Kenaf/cotton
Blend Fabrics”, Textile Chemist and Clorists, 1999, 31(3), pp. 1-5.
Ramaswamy, G.N., B. Soeharto, C.R. Boyd, and B.S. Baldwin, “Frost kill and kenaf
fiber quality”,
Industrial Crops and Products, 1999, 19, pp. 189-195.
Srinivasan, M., and Gatewood, B.M., “Relationship of Dye Characteristics to the
Ultraviolet Protection Provided by a Cotton Fabric,” Textile Chemist and Colorist, Sept.
1999, 31(9), pp.
Tao, W., Yu, C., Calamari, T. A., and Chen, Y., Preparation and Characterization of
Kenaf/Cotton Blended Fabrics, Textile Research Journal, in press.
Ying Zhou and Patricia Crews, "Effect of OBAs and Repeated Home Laundering on
UVR Transmission through Fabrics," Textile Chemist and Colorist, November 1998,
30(11), pp.19-24.
Patent Disclosures:
Denes, F., Manolache S., Sarmadi, M., Young R., Ganapathy, R., Martienz A.,
(Disclosed to UW-Fundation, 1999) Cold-Plasma Enhanced Functionalization of
Substrates by Implantation of
Primary Amine Functionalities under Hydrazine Plasmas.
Ramaswamy, G.N., and Gatewood, B.M., Invention Disclosure 98-12, “Processing and
Bleaching of Bast Fibers (Kenaf, Flax and Hemp) for Woven and Nonwoven Textiles and
Other Products,” KSU Research Foundation (April 17, 1998)
Proceedings:
Ahn, Y.M., & Kim, C.J. , Pesticide sorption properties of selected protective clothing
fabrics. Conference Proceedings of the Korean Society of Clothing Industry, 1999,
pp.126-127.
Boyd, C.R. (1999). Kenaf classic. Abstracts 1999 Second Annual American Kenaf Society
Conference. American Kenaf Society,San Antonio, TX, pp. 28 (February 25 - 27, 1999).
Boyd, C.R., Ramaswamy, G.N., and Soeharto, B. (1999). Characteristics of lightweight
kenaf cotton fabrics. Abstracts 1999 Second Annual American Kenaf Society conference.
American Kenaf Society, 30, San Antonio, TX, pp. 31 (February 25 - 27, 1999).
Collier, B. J., Neguiescu, 1. I., Romanoschi, M. V., Goynes, W. R., Von Hoven, T.,
Graves, E., Howley, P., Warnock, M. A., Effects of Finishing and Dyeing on Service
Properties and Fibrillation of Lyocell and Lyocell-Blend Fabrics, Book of Papers, 1998
AATCC International Conference and Exhibition, Philadelphia, PA, pp. 28-37
(September 22-25, 1998).
Eom, T., Ramaswamy, G.N., and Gatewood, B.M., “Alternative Agricultural Fibers:
Comparison of Mechanical Properties of Bio-Composites Made via Polymer Extrusion
and Nonwoven Fiber Processes,” Poster Abstract, Textile Chemist and Colorist, 30(8):47
(Aug. 1998).
Goynes, W. R., Tao, W., Graves, E. E., Day, M., Yachmenev, V., Calarnari, T. A.,
Peters, J. G., Neguiescu, 1. I., and Chen, Y., Fabrication and Finishing of Nonwoven
Blankets from Recycled Fibers, Book of Papers, 1999 AATCC International Technical
Conference and Exhibition, Charlotte, NC, pp. ____ (October 13 - 15, 1999).
Iyer, A., Gatewood, B.M., Ramaswamy, G.N., “Alternative Agricultural Fibers:
Development and Performance of Wheat Straw as Compared to Wood-Based Fiber
Boards,” Poster Abstract, Textile Chemist and Colorist, 30(8):47 (August 1998).
Lumley, A.C., and Gatewood, B.M., “Effectiveness of Selected Laundry Disks in
Removing Soil and Stains from Cotton and Polyester,” Book of Papers, 1998 AATCC
International Technical Conference and Exhibition, Philidelphia, PA, pp. 58-67 (Sept.
22-25, 1998)
Ramaswamy, G.N., Boyd, C.R., and Gatewood, B.M., Preliminary study evaluationg
aesthetic finished for kenaf/cotton fabrics. Abstracts 1999 Second Annual American
Kenaf Society Conference. American Kenaf Society, San Antonio, TX, pp. 8 (February
25 - 27, 1999).
Scheyer, Lois E., and Annacleta Chiweshe. Application and Performance of Disperse
Dyes on Polylactic Acid (PLA) Fabric, Book of Papers, 1999 AATCC International
Technical Conference and Exhibition, Charlotte, NC, pp. ____ (October 13 - 15, 1999).
Srinivasan, M., and Gatewood, B.M., “A Preliminary Study on the Influence of Dyes on
the Ultraviolet Protection Factor (UPF) of Fabrics,” Book of Papers, 1998 AATCC
International Technical Conference and Exhibition, Philidelphia, PA, pp. 361-370 (Sept.
22-25, 1998).
Wang, J., Ramaswamy, G.N., and Gatewood, B.M., “Alternative Agricultural Fibers:
Chemical Composition of Lignocellulosic Fibers as Affectec by Processing and
Bleaching,” Poster Abstract, Textile Chemist and Colorist, 30(8):47 (Aug. 1998).
Wu, J., and Gatewood, B.M., “Bleaching and Dyeing of Wheat Straw - An Alternative
Cellulosic Fiber for Potential Industrial Applications,” Book of Papers, 1998 AATCC
International Technical Conference and Exhibition, Philadelphia, PA, pp. 58-67
(September 22-25, 1998).
Theses and Dissertation:
Li, B. Effects of selected chemical finishes on fabric hand and fabric performance
characteristics of a microfiber polyester/cotton blend fabric. M.S. Thesis, University of
North Carolina at Greensboro, Greensboro. 1998.
Srinivasan, M. Influence of Dyes on the Ultraviolet Protection Factor (UPF) of Fabrics.
Ph.D. Dissertation, Kansas State University. 1999
Approved:
Gita N. Ramaswamy March 27, 2000
____________________________________ ___________________
Chair, Technical Committee Date
William H. Brown March 27, 2000
____________________________________ ___________________
Administrative Advisor Date
Ecodesign 3 project: New jute products for the European market
by: Claudia van Riet
at: New Central Jute Mills, Calcutta, India
February 1997
Assignment
The main subject of this project is the search for new jute products for the company New
Central Jute Mills (NCJM). NCJM has to innovate as the market of traditional jute
products like sacking and hessian has declined dramatically due to the shift of jute users
to synthetics and other fibers like kenaf. As a result NCJM aims to increase the
production of non-traditional products and start to export these products because of the
higher margins provided by the export market.
Participants
* New Central Jute Mills (NCJM), India
* Indian Jute IndustriesÕ Research Association (IJIRA), India
* Artifort, the Netherlands
Project
Due to environmental considerations, a new market demand which demand for
environmentally sound materials is emerging in Europe and elsewhere in the world. As
jute is an environmentalIy sound material this development might provide opportunities
for NCJM. However, any innovative jute application shouldnÕt just be based on
environmental aspects, also other characteristic properties of jute should be important
incentives. With the help of a brainstorm session and the knowhow of specialists new
product opportunities were generated. The most promising opportunities; jute geotextiles,
jute insulation material, technical textiles, compostbags and jute composistes were
analyzed on their potential for NCJM. Based on this analysis, jute geotextiles were
selected for further development.
In cooperation with NCJM three types of geotextiles were developed: two soil savers and
a geocell. A telephone research was held in The Netherlands in order to formulate a
marketing strategy.
* Soil saver: used to prevent soil erosion on taluds along roads, rivers etc.
* Geocells: used to prevent soil erosion on steep taluds like waste fills Ê
Inside New Central Jute MillsÊ
General improvements
As jute geotextiles can be produced with the current technology NCJM is able to innovate
without making huge investments. Moreover, as the quality requirements of geotextiles
are related to the current products of NCJM, the time to the market will be low. NCJM
has been informed about the participants on the geotextile market. To enter the market a
demonstration project with a company interested in these geotextiles should be initiated.
Ê
Prototype of jute soil saver
Prototype of jute geocell Ê
Environmental improvements
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The developed geotextiles protect the soil against soil erosion.
ItÕs moisture regaining capacity stimulates plant growth.
The jute geotextile degrades after fulfilling its function and increases the biomass
while a synthetic geotextile remains in the soil when it becomes superfluous.
Jute is a low impact, renewable material.
Nonwovens are found nearly everywhere when it comes to the medical market.
With the rise of infectious diseases and standards enforced in hospitals and
healthcare facilities, it is no wonder roll good manufacturers are seeing high
consumer demand for nonwovens with better protection in the medical market.
Currently, nonwovens can be found in a wide variety of medical-related areas,
including facial masks, surgical packs, gowns and drapes, sterilization packaging,
gloves, surgical accessories and even protective footwear and hoods. Hospital
rooms are also no stranger to nonwovens, as they can be found in bedding, pillows,
towels and linens. Considering the number of hospitals, healthcare facilities and
medical employees, it is not surprising nonwovens manufacturers cannot even
begin to guess how big the medical market really is.
According to research conducted by INDA, Association of the Nonwoven Fabrics
Industry, Cary, NC, it is estimated that medical and surgical applications consume
slightly more than three billion square yards of nonwoven fabric in the U.S. and
Canada alone each year. The result: nonwovens manufacturers have their work cut
out for them as they try to find a balance between catering to high consumer
demands and producing nonwovens that offer the best protection and comfort.
One key trend being seen in this category is the push for hospitals to use
disposables. While disposables are safer for hospital use, there is a question about
the amount of infectious waste created once they are thrown away.
Charlie Granger, business development manager for Johns Manville’s Filtration
Division, Denver, CO, sees safety as the biggest reason why nonwovens are
preferred in the medical market. “Disposable nonwovens are strerilized, packaged,
opened and then disposed of, so there is less risk of contamination before or after
use than would be the case with a reusable product,” Mr. Granger said. Although
Johns Manville’s medical business comprises well less than 10% of its roll goods
sales, the company is still witnessing strong consumer demands and concerns
regarding safety. “Everyone is coming up with something new they would like to
see. Right now we are working to develop our surgical face mask media and we are
upgrading products we already sell,” he said.
Mario Saldarini, commercial director of Orlandi SpA, Varese, Italy, believes that
medical nonwovens are growing most quickly in European markets, particularly
France, Germany and the U.K., but are stagnant elsewhere. “Nonwoven material is
commonly being found in swabs, gauze and plaster substrates,” Mr. Saldarini
added. “We are finding more nonwovens in the medical area, but in my opinion,
they are seeing very slow growth.” Orlandi’s medical production makes up 20% of
its business whereas 70% of the company is dedicated to the hygienic and cosmetic
industry, which is seeing more rapid growth. Mr. Saldarini said that hospitals need
to change their mindsets for nonwovens to gain greater marketshare in the medical
market. “Hospitals have to get rid of their mentality that disposables are luxuries.
Reusable cotton gauze can then be replaced with disposables. Disposable
nonwovens give customers more security and peace of mind,” explained Mr.
Saldarini.
Guan Tao, an import and export executive at Hangzhou Advanced Nonwovens,
Hangzhou, China, credited new fiber developments for the drive for nonwovens.
“Along with developments of new manufacturing, compound and finishing
processes in the nonwovens industry and the development and application of new
fiber and auxiliaries, nonwoven medical products have been endowed with superior
functions. They have more advantages than traditional materials,” he said.
On A Wider Scale
Consumers are among the major influences on nonwovens
production. Whatever consumers demand, manufacturers
try to match. JM’s Mr. Granger said he noticed the highest
consumer demand in more protective medical nonwovens.
The rise of infectious diseases, such as AIDS, HIV and
Hepatitis, and, more importantly, an increased awareness of
these diseases has medical consumers requesting protective
apparel.
“There is an increased awareness in the importance of barrier properties in
nonwovens. The quality of disposable nonwovens has created a whole new tier of
products,” said Mr. Granger. Some common advantages most manufacturers agree
on is that they are cheaper, disposable and more flexible to customers’ needs.
“Possibilities are really endless,” noted Mr. Granger.
Ray Dunleavy, business manager of BBA Nonwovens, Simpsonville, SC, said that
in the U.S. medical market, nonwovens have more or less fully penetrated most
apparel and packaging applications. These include products for the operating room
such as surgical gowns and drapes, head and shoe covers, face masks, sponges,
towels, wipes and sterilization wraps. In other parts of hospitals and healthcare
facilities, nonwovens, including pulp-based fabrics, are found in isolation gowns,
exam and patient gowns, lab coats, wipes, towels and bed linens.
“Nonwovens performance in the areas of protection, comfort and cost are the key
drivers for the change in this market, and this fosters competition between different
nonwoven fabric technologies. For example, the high levels of protection and low
cost offered by SMS technology are propelling it to marketshare gains in the
surgical gown and drape market at the expense of spunlaced technology,” Mr.
Dunleavy explained. “However, further gains versus reusable fabrics that are not
nonwoven will occur very slowly.”
Cost remains a huge factor when it comes to developing nonwovens and with the
implementation of OSHA (Occupational Safety and Health Administration) laws,
came many new standards for hospitals. “Basically what we saw was a spike in
demand while all the facilities took steps to fill their cupboards with disposables,
and then sales returned to a more normal level,” said JM’s Mr. Granger, regarding
the action many medical and dental facilities took in response to OSHA’s
standards. OSHA regulations called for employers to provide protective equipment
for their workers, mandating that nonwovens used is hospital and healthcare
facilities have better barrier protection while still offering comfort.
“Air flow and moisture vapor transmission are what makes a garment comfortable,
but with air flow also comes bacteria. Wherever air molecules can flow through the
fabric means that there is a risk that bacteria can also penetrate the fabric. There
continues to be growth in the use of composites, especially nonwovens matched
with specialty films, to provide comfort and barrier protection, but there is always a
cost-price pressure,” said Mr. Granger.
Carolyn Green, vice president of sales and marketing at Precision Fabrics Group,
(PFG) Greensboro, NC, believes nonwovens are growing in the international
medical market but cost will be factor. “There is always a pressure with cost.
Manufacturers are always trying to find better properties with a lower cost,” Ms.
Green said. PFG, which is mostly involved in the composite market, is developing
several new products for its medical division and is currently a leading innovator of
value-added nonwoven fabrics for the global medical products market, according
to company executives. PFG targets a wide range of end uses encompassing
products such as surgical gowns, drapes, masks, wound dressings and table covers.
Orlandi’s Mr. Saldarini added, “Synthetic nonwovens are lint-free, pure and have
more stable prices when compared to cotton, which usually sees prices jumping up
and down. Synthetics tend to be more stable.”
It is clear nonwovens have advantages for use in areas of the world where
consumers can afford them. However, in developing countries where health
standards are not as strongly enforced as they are in the U.S., the future of medical
nonwovens is questionable. Serkan Gogus commercial director for Mogul
Nonwovens, Baspinar, Gaziantep, Turkey, forsees a strong and quick growth for
nonwovens in the medical market. “Nonwoven material is found nearly
everywhere, in emergency, surgery and patient care,” Mr. Gogus said.
Mogul is currently trying to develop its market outside of Turkey. “We expect to
see growth in developing regions, such as the Far East, Eastern Europe and South
America,” Mr. Gogus projected. “We are also introducing our new SMS fabrics,
aside from our spunbonded fabrics.”
The use of nonwovens in the medical markets of developing countries is expected
to be much lower than the U.S. and other economically advantaged countries due
to significantly less household income. “As countries move from third world status
to second world, they begin to focus on medical issues,” said JM’s Mr. Granger
“Health and sanitary issues are a big problem in these countries, but so are
financial constraints. People in third world countries are making $200 a year so
they are going to have trouble affording one sanitary product that costs four
dollars.”
“Western Europe and Japan have higher growth rates than the U.S. market (in the
5-10% range) while Asia, Eastern Europe, South America and the Middle East are
growing even more rapidly. Education on the clinical and economic benefits of
nonwovens directed at health officials and practitioners in these regions result in
increasing demand,” said BBA’s Mr. Dunleavy.
The medical nonwovens industry in the U.S. has remained relatively mature,
according to Mr. Dunleavy. “The U.S. market is growing at 1-2% annually.
Growth is driven by increases in surgical procedures stemming from our aging
population, which is offset by a reduction in nonwovens used per procedure
resulting from advances in surgical technology and less invasive techniques,” Mr.
Dunleavy explained.
Hangzhou’s Mr. Tao believes that nonwovens are growing very quickly in China.
“Along with the continuous growth of the national economy, China is going to
establish an integrated system of medical treatment and healthcare step by step to
upgrade people’s health and improve the instruments used in medical treatments
continuously,” said Hangzhou’s Mr. Tao.
Spunlace Comes In First
Manufacturers all seem to agree that one of the most preferred nonwovens
technologies used in the medical market is spunlaced. “Spunlaced is really used
most often, especially in surgical rooms or anything that involves direct contact
with the skin,” said Mr. Saldarini.
Additionally, the absence of chemical treatment in spunlaced material makes it a
fabric often favored in the medical market. JM’s Mr. Granger agreed. “Spunlaced
and SMS are most commonly used because they are the most fabric-like. It’s a
combination of barrier protection and comfort,” he said.
Spunlaced nonwovens are made by entangling polyester fibers with a layer of
wood pulp, whereas SMS materials feature a composite of three layers—spunlace,
meltblown and spunbonded—normally using a polypropylene resin and then being
stacked together.
BBA’s Mr. Dunleavy said that nonwovens are suitable in protective medical
devices for a variety of reasons. “Suitability depends on end use application, as
nonwovens can be designed to be absorbent or repellent, breathable or impervious,
with film lamination or soft and stiff,” Mr. Dunleavy said.
“Spunlace is most suitable because there are no chemicals used during the
hydroentanglement production process and it makes it very hygienic and sanitary.
Spunlace is soft and the surface will not become damaged,” Hangzhou’s Mr. Tao
said. “Spunlaced nonwovens can produce both light and heavy weight products
with different degrees of softness,” commented David Farrar, managing director of
BFF Nonwovens, Bridgwater, Somerset, U.K.
BFF fabrics go into swabs, fixation tapes, non-adherent dressings, disposable
drapes, surgical gowns, ostomy bag components and wipes.
But spunlace is not the only nonwoven technology finding application in the
medical market. For instance, BBA Nonwovens uses several different technologies
to manufacture fabrics for the medical market, including high barrier SMS fabrics
for surgical gowns, drapes and CSR wrap applications.
Additionally, spunbonded fabrics are used more for non-sterile apparel and
laminate structures and wetlaid fabrics are used more for disposable linens. Johns
Manville uses spunbonded polyester, meltblown polypropylene and polyester to
produce its nonwovens for the medical market.
Innovations Underway
Bacteria control must also be considered when producing a
nonwoven, especially one that is going to be used in the
medical market. Foss Manufacturing, Hampton, NH, has
recently introduced a new antimicrobial line to assist in
preventing bacteria from growing. “Fosshield
Antimicrobial Technologies” effectively guards against the
growth of a broad spectrum of odor-causing destructive
bacteria, mold and mildew. With its added level of product
protection, Fosshield fiber allows for applications across a wide range of products
that are vulnerable to the effects of bacterial degradation, including bed linens,
towels and wound care. The new antimicrobial technology is derived from an allnatural, silver-based inorganic composition. Silver, one of the oldest known
antimicrobial agents, has been proven effective in protecting fibers and fabrics
from a broad spectrum of destructive and odor-causing bacteria, mold and mildew,
according to company executives.
Fosshield uses a proprietary patented process developed by Foss for incorporating
the advanced silver-based agent into the bicomponent (two polymers/additives) and
binder (adhesive) fibers of fabrics. A continual delivery system ensures the slow
release of silver. The result is a fabric that maintains efficiency of its antimicrobial
protection for the longevity of the product and can withstand multiple launderings.
There are several other new Fosshield products currently under development that
are intended for use in the medical industry for mattress pads, pillows and hospital
scrubs.
Among the latest developments from Hangzhou are improved plaster substrates.
“We have plaster nonwoven substrates that have high blood-absorbency and are
soft,” Mr Tao said. “Our new plaster substrates offer a different spunlaced fabric
structure that offers more comfort.”
Nonwovens sometimes need to receive a chemical treatment to prevent water,
blood or bacteria from seeping through the fabric. Chemical treatments applied to
nonwovens can range from a water repellent substance to a film. According to
INDA surface treatments adapted or borrowed directly from traditional textile,
paper or plastic finishing technologies are used to enhance fabric performance or
aesthetic properties. Examples of performance properties are moisture transport,
absorbency or repellency, flame retardancy and abrasion resistance. Fabric
finishing is either chemical, mechanical or thermal-mechanical; chemical finishing
allows for dyestuffs, pigments or chemical coating applications on fibers.
Disposables Forecast Bright
Manufacturers agree that the future of nonwovens looks promising, if certain
obstacles are addressed during production. “The future of nonwovens looks bright
as markets move more toward disposable products. As new treatments and methods
of care are developed, the possibilities for the use of nonwovens can only
improve,” said BFF’s Mr. Farrar. However, Mr. Farrar also noted that people may
be unwilling to switch products if something they use already works well.
Additionally, many medical products have a long development time, which can be
difficult to overcome.
The flexibility of nonwovens remains a key characteristic as the future of
nonwovens in the medical market is speculated. “Nonwovens will continue to
adapt to meeting the changing needs of the medical market, be it in the structure or
composition of the nonwoven itself or in combination with other materials or with
post treatments,” BBA’s Mr. Dunleavy projected. “Flexibility and adaptability at
low costs will contribute to its success. The wide variety of technologies and fibers
enables nonwovens to be engineered to meet the specific needs of each different
end use application.”
Nonwovens manufacturers agree that nonwovens will see success in the future with
the development of newer and hi-tech materials in the medical market. “Factors
that will bring success to nonwovens in the medical market also involve medicine,
new-type and higher-tech materials, which will support their development,” said
Mr. Tao. To achieve this growth, nonwovens have several obstacles to overcome.
“The low-speed development of the fiber industry may limit the developing speed
of nonwovens for medical products. Also, the degree of acknowledgement and
understanding about nonwovens for medical products in different countries will
limit their popularization and applications as well as development of nonwoven
medical products in such countries,” Mr. Tao said.
Most manufacturers agree that nonwovens are key when it comes to the medical
market. The main cloud that still lingers overhead is the question of what becomes
of the disposable after it is thrown away.
“The waste treatment after usage will bring certain pressure to society and the
environment due to the increased use of disposable nonwovens,” offered Mr. Tao.
With manufacturers busy developing new products, they just might discover a solution with disposables
p76 /sIV –6
Application of Geotextiles and Vegetative Reclamation for the Stabilization
and Erosion control of the Overburden Dump
Abhay Kumar Singh, T.B. Singh, P.K. Singh & B.K. Tewary
Central Mining Research Institute, Barwa Road, Dhanbad – 826 001
Excavation of mineral by opencast mining method involves the removal of overlying
soil and rock debris as overburden, which are dumped nearby. These overburden
dumps modify the land topography, affects the drainage systems, prevent the
natural succession of plant growth resulting an acute problems of soil erosion and
environmental pollution. During rainy storms, the surplus water flowing down the
sloping surface of the dump remove soil particles from large areas and causing
formation of closely spaced rills, which may form wider gullies in advance stage of
erosion. Such erosion processes may bring instability to the dumps. Gully erosion is
most difficult and expensive to control. Some sheet and rill erosion is inevitable, but
if proper care is taken, gully erosion can be avoided. Application of new generation
geotextile with special design features could be an effective alternate to provide
solution for erosion problems and speed up the vegetation process. Geotextile like
jute, coir and other natural geotextile are effective environmental friendly and
biodegradable. Natural geotextile is the effective tools for erosion control and
providing soil stabilization as well as environment for natural vegetation. It decays
too slowly and supports the fertility status of the soil as nutrient and natural
vegetation.
An attempt has been made to study on the application of natural geotextiles and
vegetative reclamation as effective method for erosion control, stabilization and
vegetation of mine overburden dumps.
Home
Back
These relatively new materials have become indispensable for many EC
applications.
By Lynn Merrill
Mention the need to use a geosynthetic on your next project, and you might have
opened the gateway to the amazing and sometimes confusing array of products that
can perform a wide variety of engineering functions at your project site. The challenge
is to understand which products perform what functions in order to pick the right one.
Some products are designed to retain soils in place; others allow waters to flow
through while reducing the amount of silt in the water flow. Some are designed to
prevent any water flow, while still others help direct water through the site to minimize
erosion. Understanding the needs at the site, the soil characteristics, and the desired
outcome all will help in the selection process.
A Geosynthetic for Every Application
Geosynthetics are a broad class of materials designed primarily for use in engineered
earth applications. These materials are used in locations where biodegradation could
be a problem and in situations in which the inherent strength and durability of the
material are useful.
Most geosynthetic materials used in EC applications are made of plastic, nylon, or
other synthetic materials and may contain other chemical components added to create
certain physical characteristics. Geosynthetic materials are divided into several
different subcategories:
Geomembranes. On a dollar-for-dollar basis, geomembranes are probably the largest
category of geosynthetics. According to the Geosynthetic Research Institute (GRI),
geomembranes are "impervious thin sheets of rubber or plastic material used primarily
for linings and covers of liquid- or solid-storage facilities."
GRI notes that although "nothing is strictly impermeable," when compared with
competing materials such as natural or amended clay–substances with an
impermeability of 10-7 cubic meters per second (m3/s)–geomembranes offer a much
smaller diffusion permeability of 10-11 to 10-13 m3/s and are considered relatively
impermeable. There are more than 30 different engineering applications for
geomembranes, and these applications often are used in EC applications to line catch
basins and settling ponds.
Geotextiles. Geotextiles are the second largest category of geosynthetic products.
Classified as textiles because of their fabriclike consistency, geotextiles consist of
synthetic fibers, which are highly resistant to degradation when in contact with soil or
water.
Both woven and nonwoven geotextiles are manufactured. Both are porous to water
flow both across and through the sheet, although the density of the weave or matting
determines the porosity through the fabric. According to the GRI, at least 80 specific
applications have been identified for this group of products, and determining the
specific needs of the site can help determine the appropriate product.
Geogrids. Unlike geotextiles, geogrids contain relatively large open spaces. Geogrids
are used primarily for reinforcement, such as for soil reinforcement in the construction
of retaining walls. This segment of the industry is rapidly growing, with at least 25
different applications already identified.
Other geosynthetic categories include geonets or geospacers, designed to move water
through a drainage area, and geosynthetic clay liners, impervious products consisting
of clay sandwiched between layers of geotextile or geomembrane. These geosynthetic
materials often are used at landfill sites or to prevent fluid infiltration into adjacent soils.
As geosynthetic materials find new applications, geocomposites are often created,
either by combining more than one geosynthetic product–a geogrid and geotextile, for
example–or by combining a geosynthetic with another type of material. By combining
the different products together, it is possible to create synergisms and reduce the need
to use individual products to achieve the desired results. Geosynthetics, a growing
area of research within the industry, produces new products and applications–
designed to meet unique engineering needs–on a continuous basis.
Deciding What You Need It to Do
Each subcategory of geosynthetic products is
designed to perform a specific function. To
select the right product, it is important to
understand the product’s function or functions
and the physical characteristics needed to
meet those functions. Product functions can
include separation, reinforcement, filtration,
drainage, and creation of a moisture barrier.
Separation. It is sometimes desirable to
maintain a physical separation between two
dissimilar materials to maximize the physical
Geosynthetics are often used to reinforce attributes of each of those materials. For
plant roots.
example, in drainage systems, it is necessary
to prevent fine soils from filling the voids in a rock base, otherwise the drainage system
becomes clogged and ineffective over time. Yet it is important to allow water to pass
between the soil and the drainage system.
In other applications, it is desirable to prevent any water from coming into contact with
the soil, so an impervious separation surface is required. The selection of an
appropriate product to achieve a physical separation is determined, therefore, by the
desired outcome.
Reinforcement. The physical characteristics of soils, especially on slopes resulting
from cuts and fill activities, create an opportunity for soil to go where you don’t want it
to go. Geosynthetic products can help to strengthen the soil face and to increase the
soil’s ability to stay put. As a result, slopes are stabilized either temporarily or
permanently, and creep stops or at least diminishes. Also, geosynthetics can be used
either to prevent water from permeating a slope or to control the amount of infiltration
that occurs during various rain events.
Filtration. Often it is necessary to filter out fine soil particles that are in suspension as
a result of severe rain events at a site. The size of the particles, the flow rate of the
water, and the physical location of the filter may determine the types of products that
are appropriate. Products used as silt curtains in a flowing waterway require higher
strengths to reduce failure than products used to contain occasional runoff from a
construction site.
Drainage. In some locations, water must be removed from a location–such as a
building foundation–quickly, or flow must be directed from the face of a slope to a
channel or pipe to reduce sheet erosion. In these applications, a product that has a
relatively low permeability and high resistance to abrasive materials–or that has the
ability to redirect water along a desired path–is necessary.
Moisture Barrier. In some locations, it is important to prevent moisture from reaching
certain materials, such as wood along a foundation. Although not directly applicable to
erosion control, such features might be desirable in sensitive locations.
Engineering a Solution
Once it’s clear what function the geosynthetic material must perform, it is then
necessary to determine the actual product or combination of products that meet the
required application. It’s also necessary to consider the physical configuration of the
site, soil type, and expected flow rates of water over the soil requiring protection.
For most applications relating to highways and roads, the American Association of
State Highway and Transportation Officials (AASHTO) has developed guidelines that
have been adopted by the United States Department of Transportation of a substantial
number of states. "These guidelines were set up as a joint effort between the AASHTO
organization, the highway officials, and the geosynthetics industry," states Steve
Walker, a consultant with Hancor Inc. in Findlay, OH. "There are classifications, based
on the difficulty of the construction site itself and the mechanical stresses to which the
material would be exposed during installation."
According to Walker, a major motivation behind establishing these classifications had
to do with recognizing the damage that could occur during the course of the
installation. "The industry found out over the years that installation damage is a real
key factor with these products," he explains. "They have to remain intact during the
installation process. For example, in an erosion control application, you have to make
certain that the surface is very clear of significant stones, roots, and debris. It has to be
as smooth as possible and free of depressions or holes in the soil surface. One of the
key things you are trying to accomplish in erosion control applications is to make
certain that the geotextile is in intimate contact with the soil itself so that it can function
and do its job. Once it’s installed in place, bedding stone will be placed over the top;
these materials have to be placed very carefully. It’s very easy to drop stone and rock
on top of geotextiles and damage them. So we have to observe some guidelines."
Despite the focus on the AASHTO guidelines, actual requirements vary from state to
state, says Jay Wilson, a technical services engineer for Linq Industrial Fabrics Inc. in
Summerville, SC. "A lot of states have gone into their own testing applications,
depending on the problems they may have had in the past."
Often, states have their own sets of acceptable products for certain applications on
highway projects. "The engineer will specify by the state standards something on their
approved products list for a [specific type of] erosion control," explains Wilson. "The
contractor knows right off what he’s got. But with private jobs, we run into a lot of
specifications that just don’t make sense for the job or are from something really
outdated."
Standard formulas and published information, such as the Universal Soil Loss
Equation, can be used to calculate the expected erosion; this information might also
form the basis for designing a solution, notes Richard Goodrum of Colbond in Enka,
NC. "You can pretty much stick in numbers available to designers to come up with an
answer," he claims. "But they only are used as a general rule of thumb. For channels,
we recommend a designer follow the procedures set forth in Highway Engineering
Circular 15 that’s published by the Federal Highway Administration. In there are stepby-step procedures. Then you compare [that result] to what you are expecting in the
channel with what is permissible." Goodrum’s company plans to release software that
helps designers calculate solutions for slopes and channels after entering the slope
geometry and other parameters.
Applications in the Field
Once the desired application has been determined, the engineering has been
performed, and the products have been identified, the challenge is to install the
geosynthetics properly in the field. The best engineering in the world will fail if the
products are installed improperly or if the materials are damaged during installation. To
minimize these possibilities and to get the best results, it is desirable to use
contractors who have experience installing the products and can make appropriate
adjustments based on what they see in the field.
Silt Fences. One common EC application for geotextiles is in silt fencing to control
sediment runoff, as from a construction site. Geotextiles are ideally suited for this
application because of their ability to filter suspended soils from the flow. The design
and installation of these fences are a function of the expected flow rates off the site.
A recent project involving silt fence installation at a newly constructed school in
Washington, DC, presented a challenge for Bruce Burgess, owner of J&B Fabricators
in Arnold, MD. The project demonstrates how important it is to hire people who
understand the actual dynamics and proper installation of geosynthetics.
"Part of the business that I like and is the most rewarding is when someone has a
problem," affirms Burgess. "They call us up and say, ‘What can we do here to make
this work?’" In the school project, the original design called for standard silt fencing,
which consisted of geotextile anchored to standard stakes. The project site contained
steep slopes, however, so Burgess recommended a product that his company
fabricates from geotextiles called Super Silt Fence. This product consists of 42-in.-high
chain link fencing faced with 45-in. silt fence fabric with a 20-40 open mesh. The fabric
is buried in an 8- to 10-in. trench along the foot, creating a strong, effective fence.
Nature, however, stepped into the picture before the EC system could be installed.
"They had a 7-inch rain in a three-and-a-half—hour period," Burgess reports. "It rained
so violently that it took some of the material that had just been excavated the day
before and moved it almost 500 feet into a backyard. It did about $8,000 worth of
damage to two residences from the sheet flow. We went in and recommended they put
in an extra layer of Super Silt Fence. This particular job was very complex in that it
ended up being over a half-mile of fence and through a lot of difficult conditions. It was
a step up from the original design, which didn’t take into account how steep the slopes
were and the fact that we have heavy summertime rains."
Such control measures must remain in place until the regulatory agencies are satisfied
that permanent EC measures are in place and that the project has been successfully
stabilized. The long-term durability of geosynthetic fabrics in such settings is
particularly advantageous. "It may take a year or two," admits Burgess. "We are
removing sediment control measures from a job today that we installed over a year
and a half ago. It was a very difficult site with a lot of retaining walls and steep slopes."
Burgess recognizes that the cost of installing geosynthetics at a job site can result in
the use of substandard products that won’t perform. "Substandard silt fences are being
distributed by people that are trying to make a buck and not paying attention to the real
problems that exist," he protests. "It’s easy to put in a very cheap fence out there. But
that’s not the point. The point is that we’re trying to protect the environment and trying
to do the job right. When someone buys that material, they are doing a disservice to
the entire industry and to the whole cause of sediment erosion control. There’s not
enough enforcement."
Riprap Installations. The installation of geotextiles under riprap is another common
application, but the potential for damage is great during installation. A variety of factors
must be considered, says Billy Egan of Engineered Fabrics Specialists in Norcross,
GA. "Instead of just putting riprap down on bare soils where the first couple of rains will
cause some of the loose settlement under the riprap to wash out, they are requiring
geotextiles that keep all the fine soil particles in place and let the water run out of the
riprap," he explains.
Selecting the right fabric to withstand the rigors of the installation process is critical to
success. "It’s important that the fabric be designed and selected to withstand the
construction damage," maintains Egan. "That depends on the size of the riprap, the
angularity, and the height from which the riprap is dropped from a backhoe or a loader
bucket. All of these are considerations that the design engineer should make to ensure
that the fabric is not ripped during the installation process." The design engineer, a
technical consultant, or the contractor might drive those decisions, but the vendor’s
experiences will help direct the right choice.
Egan expects more regulations for EC applications in the future–regulations that will
fuel the development of new geosynthetic products or applications. "As they raise the
education of people in the business–developers and contractors–about the things that
are available to them and the different techniques they can use in the staging of
projects, we’re going to see new products entering the market that try to counter the
effects of stormwater pollution. Not too many years ago, there were people that did this
as a sideline business. Now there are businesses for that purpose only–to provide
products or services that prevent the problem from happening as opposed to trying to
fix it after it’s happened."
Turbidity Curtains. Geotextiles can be installed in a flowing stream or waterway to
contain any silt that actually enters the waterways. Similar to silt fences, these
particular installations require additional strength because of the continual forces of the
flowing water against the material. The typical turbidity curtain may consist of a
flotation device installed along the top edge of the fabric, and a weight is installed
along the bottom edge to keep the material in place along the streambed.
"A turbidity curtain is basically a silt fence in water only," explains Kevin Oneill, owner
of GEOTK in Vancouver, WA. "You can’t pound stakes deep enough, so we put a
cable under the float so that you can take some runners off that cable to keep it in
place. Water really doesn’t go through it. We almost always do this in a half moon
around the project site. It redirects the flow around the project site, and then the water
that’s on the inside can’t get out. Water can transfer both ways, but these fabrics we
make it out of are pretty fine. By the time they have worked for a while, they actually
are pretty well clogged up so they can become an impermeable barrier."
Sediment Retention Bags. Another geosynthetic textile application involves the use
of sediment retention bags–in essence, a large filtering bag. "Those can be anywhere
from 15 to 20 feet wide and 50 to 100 feet long," points out Oneill. The bags are often
used in places where the contractor has not yet constructed a retention pond and has
had a rain event. "They’ll find a place where they can collect most of the muddy water
and a place to release it. We size the bag according to the time that they need to run
this and the amount of flow they are going to put through the bag. If they end up with a
small reservoir of extremely muddy water that they somehow have to clean up, they’ll
just pump it out of that settlement area through the bag."
Once the bags have been used, their size and the layer of silt collected make removal
difficult, so Oneill usually tries to locate these retention bags in places where they can
be incorporated into another use. "We try to place the bag in an area that might end up
with a roadway over it so that it can just stay in place," he asserts. "The amount of silt
in it, even if it’s pretty well used up, will only be 2 to 3 inches throughout the bag. They
are very hard to haul off. We can either cut the top open, take that fabric away, and
leave the silt in place or have it placed where it’s going to be buried and not disturbed."
The Industry Is on Solid Ground
Oneill notes that the industry as a whole is settling down. "Cost is becoming quite an
issue, and I think the agencies are going to demand better erosion control," he
observes. "The best way to control erosion is to keep it on the slope or on the ground.
Don’t allow the soil to move. There’s been a lot of energy put into trying to control it
once it’s in the water or flowing over the land in water. Once you’ve reached that point,
you’ve lost the battle."
He sees a movement toward an integrated approach, one that uses the various
features and properties of each class of geosynthetics to maximize the total EC
package at a site. "If you’re doing your job up the slope, the catch basin insert will last
a long time, but when you’re trying to use it as an end-all, it doesn’t work. And all of
these products are available, developed, and ready to go. It’s basically back to the
basics of getting the slopes covered and planning the erosion control before the
problem happens. As much as erosion control has gone forward, it’s still not being
used to its potential."
Lynn Merrill is director of public services for the City of San Bernardino, CA.
Search | Subscribe | About | News | Advertise | Register | Services | Calendar
Glossary | Contact Us | Current Issues | Back Issues | ForesterPress
Copyright 2001-2002 FORESTER COMMUNICATIONS, Inc.
P.O. Box 3100 * Santa Barbara, CA 93130 * 805-682-1300
Erosion Control Product Charts
Your Slope Design Criteria:
Slope Gradient: < = 5.0:1.0
Required functional longevity of RECP: > 3 months and < = 12 m
Recommended RECP: ECTC Type 2a Short Term Degradables
Short term degradable RECPs consist of mulch control nettings (MC
weave textiles (OWTs) designed to control erosion and enhance veg
for up to 12 months.
Product
Name
Product Manufacturer
RECP
Type1
Composition
No.
of Net type2
nets
Eco-Jute®
Belton Industries, Inc.
OWT
GeoJute®
Belton Industries, Inc.
OWT
GeoJute
Belton Industries, Inc.
OWT
Stabilizer®
ECS STD
Erosion Control Systems ECB
Straw
ECS STD
Erosion Control Systems ECB
Excelsior
S 31
ErosionControlBlanket.com ECB
S75 ™
North American Green
ECB
S75BN ™
North American Green
ECB
FUTERRA®
Landlok®
ENS1®
Landlok®
S1
Matrix
Jute
Jute
Jute
1 Synthetic
Straw
1 Synthetic
Excelsior
1 Synthetic
1 Synthetic
1 Organic
Straw
Straw
Straw
Wood /
Synthetic
Polypropylen
Profile Products LLC
ECB
SI Geosolutions
ECB
1
Organic
Straw
SI Geosolutions
ECB
1 Synthetic
Straw
Landlok®
407 GR/GT
ERO-MAT®
V75S (SD)
ERO-MAT®
V75EX (SD)
R-1RG
SR-1
Premier
Straw
Blanket®
Curlex®
Excelsior
Blanket
SI Geosolutions
OWT NA
NA
NA
Verdyol Plant Research
ECB
1 Synthetic
Straw
Verdyol Plant Research
ECB
1 Synthetic
Excelsior
Western Excelsior
Western Excelsior
ECB
ECB
American Excelsior Co
ECB
American Excelsior Co
ECB
1 Synthetic Excelsior
1 Synthetic
Straw
Synthetic
1
or
Straw
Organic
Synthetic
100% Aspe
1
or
Excelsior
Organic
This table consists of product/s each manufacturer typically recommends for the a
convenient website link provided will take you to the manufacturer's website wher
and specific design data.
1
RECP Types:
ECB = Erosion Control Blanket OWT = Open Weave Textile MCN = Mulch Control Net
2
Synthetic or organic netting
3
Note: Functional longevities discussed herein are offered for guidance purposes o
based on site and/or climatic conditions. The RECP manufacturer can assist you in
based on the climate the material will be used in.
Disclaimer: This chart contains only general recommendations for the use of comm
products (RECPs) and must not be used for actual product selection without consid
The manufacturer of the product listed has provided all performance values shown
by independent test data. The ECTC and its members accept no liability for misuse
data and design procedures for the products listed, along with detailed recommend
click on the hotlink to the product manufacturer's web site or contact the supplier
Top of Page
About ECTC | Directing Members | Associate Members | Links | Co
What are RECPs? | Uses & Results | Product Information | Testin
Specification Guidelines | Resource Center | Members
© 1998-2002 by Erosion Control Technology Council. All Rights Reserved. Text, graphics, images, and HTML cod
may not be copied, reprinted, published, translated, hosted, or otherwise distributed by any means without ex
contact michael@cybertizing.com.
Erosion Control Technology Council
Laurie Honnigford, Exec. Director
P.O. Box 18012
St. Paul, MN 55118
(651) 554-1895
(651) 450-6167 fax
info@ectc.org
Designed
Rolled Erosion Control Products (RECP)
2002-2003 NTPEP Application for Bench-Scale Testing
~~~1st CYCLE DEADLINE EXTENDED TO JAN. 15, 2003~~~
(Source: ECTC) The enormous problem of uncontrolled soil movement b
control industry. The magitude of the problem is often overlooked by those unfam
example, sediment the by-product of erosion) accounts for more than two-thirds o
Annual spending in the U.S. for mitigation of erosion and sedimentation is estima
.
.
The erosion control industry consists of a broad range of diverse professions and
blanket manufacturers, consulting engineers, landscapers and even earth moving
interrelated segments of this market. This army of professionals have two objectiv
the trapping of sediment before it enters the waterways..
.
One of the most rapidly growing and "high tech" segments within the industry has been the erosion control mat and bla
(i.e. mats and blankets) were first used in the form of jute mattings imported from Asia, but have quickly evolved to inclu
products. As the demand for mats and blankets grew, several different products were developed utilizing varying comp
products work in conjunction with vegetation to form a biocomposite solution to erosion control problems. The mat and
blending the professional disiplines of engineering (mat and blanket products, channel hydraulics, etc.), agronomics, an
variety of product types together with the blending of professional diciplines has led this segment of the industry to "sel
rolled erosion control products. -NTPEP-
Chair: Peter Kemp, Wisconsin DOT
Vice Chair: Steve Hall, Tennessee DOT
EROSION CONTROL PRODUCTS PROJECT PANEL
A BRIEF HISTORY OF THIS PROGRAM
PROJECT WORK PLAN
BENCH-SCALE TEST METHODS
SUBMIT A PRODUCT (2003 CYCLE)
INDUSTRY RESOURCES
EROSION CONTROL PRODUCTS PROJECT PANEL -- The NTPEP Project Panel is the working group charged
Work Plan, for testing of a particular product, material or device. The Project Panel convenes at least annually, in conju
Project Panel membership may range from six to ten AASHTO members, and up to two Industry members assigned by
NAME
ORGANIZATION
Peter Kemp
(Chairman)
Wisconsin DOT
Steve Hall
(Vice Chairman)
Tennessee DOT
Tony Johnson
(Industry Member)
American Excelsior Company
Tim Lancaster
(Industry Member)
North American Green, Inc.
1
2
3
4
5
6
A BRIEF HISTORY -- In 1998, the NTPEP Oversight Committee determined that NTPEP should consider conduct
"erosion control products." Their initial discussion revolved around the different types of erosion control products. It was
Products (RECP)" should be evaluated first, since they are widely used by state and local DOTs.
After considerable debate the NTPEP Oversight Committee decided to consider adopting large-scale test results, simil
Transportation Institute (TTI) erosion control lab. Around the same time, the NTPEP Oversight Committee became awa
vis the Erosion Control Technology Council (ECTC). At the time, so-called "bench-scale performance index tests" were
guidelines were gaining credibility within the industry, AASHTO/NTPEP monitored the activity in hope that it would serv
prequalification testing.
In early 2002, a dialogue sparked between the NTPEP Oversight Committee's Project Panel on rolled erosion control p
Technology Council (ECTC). From that synergy, at the NTPEP2002 Annual (National) Meeting, AASHTO and ECTC si
government and industry dialogue.
With encouragement from Industry, the NTPEP Oversight Committee pursued research funding for a study on "Correla
Testing of RECPs." The NCHRP 20-7 Task Force commissioned the study in April 2001. This research study begins w
initally participating manufacturers are included in the NCHRP correlation research study.
Traditionally, AASHTO contracts with State DOTs (AASHTO Members) to conduct lab and field evaluation on behalf of
Plan calls for recently developed test methods, there are no state DOT labs conducting such tests. Generally, State DO
testing at the scale conducted under auspices of NTPEP; for this reason, AASHTO/NTPEP has contracted with a priva
(Austin, Texas) to conduct testing on behalf of the association. As the program grows and demand warrants, additional
AASHTO/NTPEP. -NTPEP-
PROJECT WORK PLAN -- NTPEP tests products according to a Project Work Plan, which describes the laborator
the evaluation. The Project Work Plan is a consensus-based document, and includes peer review and input from indus
adopted after receiving at least two-thirds affirmative support from 52 AASHTO member states. The Project Work Plan
testing and evaluation. When implemented by state DOTs, their own state standard specifications may supersede the N
to be aware of state-level requirements, which may supersede basic NTPEP testing.
PROJECT WORK PLAN
Project Work Plan for Laboratory Evaluation of
Rolled Erosion Control Products (RECP)
[8 pages, 29 KB]
BENCH-SCALE TEST METHODS -- The NTPEP program refers to so-called "bench-scale" test methods as devel
Council (ECTC). These test methods assess index properties for RECPs. The NTPEP Project Panel on RECP decided
product prequalification. The alternative approach was to test against "large-scale testing", which can be quite costly. B
RECPs, the NTPEP Oversight Committee commissioned an NCHRP (National Cooperative Highway Research Progra
scale and large scale testing." That project is now underway.
TEST METHOD
ECTC Test Method 2 (Draft)
"Standard Test Method for
DETERMINATION OF ROLLED EROSION CONTROL
PRODUCT (RECP) PERFORMANCE IN PROTECTING SOIL
FROM RAINSPLASH"
ECTC Test Method 3 (Draft)
"Standard Test Method for DETERMINATION OF ROLLED EROSION CONTROL PRODUCT (RECP)
PERFORMANCE
UNDER FLOW INDUCED SHEAR STRESS"
ECTC Test Method 4 (Draft)
"Standard Test Method for DETERMINATION OF ROLLED EROSION CONTROL PRODUCT (RECP)
PERFORMANCE
IN ENCOURAGING SEED GERMINATION
AND PLANT GROWTH"
Memorandum on
"A Standard Vegetated Condition"
SUBMIT A PRODUCT -- NTPEP has introduced partial electronic application for its Rolled Erosion Control Products (R
applications on a rolling basis with pre-established deadlines for submitting to a particular cycle of testing. These deadl
OCTOBER 15th and DECEMBER 15th.
.
.
.
[OPTION 1] -- Electronic Application with PDF e-Forms,OPTION 1 requires the freely available Adobe Acrobat Read
drive, purchase "Acrobat Approval" from Adobe.)
DOCUMENT
Invitation to Participate in NTPEP-Coordinated Evaluation on RECP
(1 page)
"Sample Requirements, Technical Approach
and Fee Schedule"
(7 pages, 55 KB)
"PRODUCT EVALUATION FORM (PEF)"
(1 page, 490 KB)
"Fee Calculation Schedule"
(1 page, 28 KB)
.
.
.
.
[OPTION 2] -- Fax-on-Demand Application,
. . . . Request
Application by e-mail (provide your name, company and fax number)
.
.
.
INDUSTRY RESOURCES
Erosion Control Technology Council (ECTC)
U.S. Dept. of Energy, NEPA Policy and Compliance
FHWA, Office of Bridge Hydraulics
FHWA, Office of Research and Technology
WisDOT, Erosion Control Product PAL
. . . . <SUBMIT A RESOURCE LINK>
Telephone:
412-647-3555
Fax:
412-624-3184
ARTIFICIAL ORGAN RESEARCH FINDINGS PRESENTED BY UNIVERSITY OF PITTSBURGH
RESEARCHERS
McGowan Institute for Regenerative Medicine faculty present work at American Society for Artificial Internal
Organs and International Society for Artificial Organs joint meeting
WASHINGTON, June 18, 2003 - The clinical and basic science findings of more than a dozen studies are being
presented by researchers from the University of Pittsburgh's McGowan Institute for Regenerative Medicine at a joint
meeting of the American Society for Artificial Internal Organs and the International Society for Artificial Organs. Scientific
sessions take place June 18 to 21 at the Hilton Washington. Among these findings are:
Success reported in growing functioning liver tissue in a bioreactor
Growing functioning liver tissue in a fist-sized device that works in a way similar to kidney dialysis has kept patients in
liver failure alive until donor organs have become available, according to Jörg Gerlach, M.D., Ph.D., professor of surgery
at the University of Pittsburgh School of Medicine. "We have treated eight patients in acute liver failure - some of whom
were in a coma - who were able to be bridged to transplant," said Dr. Gerlach, who also is a faculty member of the
university's McGowan Institute.
Dr. Gerlach and his colleagues have been able to grow functioning liver tissue from human liver stem cells derived from
organs that had been deemed unsuitable for transplant because of damage or underlying disease. Such cells have been
shown to proliferate and form liver-like tissues in bioreactors, and persist in culture for many weeks.
About 25 million Americans - one in 10 - have liver disease, according to the American Liver Foundation. More than
43,000 people die of liver disease yearly. Annual hospitalization costs exceed $8 billion. Dr. Gerlach's bioreactor could
have an impact for the sickest of these patients, who often do not survive the wait for transplantation or become too sick
to qualify for a transplant.
These findings are being presented in a poster session beginning Thursday, June 19.
Tissue-engineered materials continue to show promise as treatment for heart defects
Research on tissue-engineered materials continue to show promise as a treatment for heart defects, reports William
Wagner, Ph.D., associate professor of surgery and bioengineering at the University of Pittsburgh School of Medicine and
a deputy director of the McGowan Institute.
Researchers in Dr. Wagner's laboratory have developed a novel, flexible and biodegradable material based on a
specialized polymer that is porous to encourage the infiltration and growth of cells. This "cardiac patch" was tested in the
repair of defects in adult rats.
After four weeks, the patches and nearby tissue were studied for evidence of inflammation, scarring and proper cell
growth. Results show encouraging levels of repair and cell regeneration with minimal signs of inflammation. "Future
application of this material as a cellular scaffold in cardiovascular tissue engineering appears promising," Dr. Wagner
said.
This work is scheduled for presentation on Saturday, June 21.
Invited lecture, symposium feature McGowan faculty
Also scheduled are discussions featuring David Vorp, Ph.D., associate professor in the departments of surgery and
bioengineering at the University of Pittsburgh School of Medicine, and William Federspiel, Ph.D., associate professor of
chemical engineering at the University of Pittsburgh.
Dr. Vorp, who also is director of the Vascular Biomechanics and Vascular Tissue Engineering Research laboratories at
the McGowan Institute, was invited to present an overview as well as new data on "Tissue Engineered Blood Vessels"
beginning at 1 p.m., Thursday, June 19. Dr. Vorp and his colleagues are working to create functioning blood vessels by
using adult-derived stem cells from bone marrow. He will discuss current research on this effort, including evidence of the
use of mechanical stress to guide the differentiation of stem cells into vascular cells.
Dr. Federspiel, who is director of the McGowan Institute's Artificial Lung laboratory, is one of five panelists taking part in a
symposium session on "Artificial Lung and Gas Exchange," beginning at 1 p.m., Friday, June 20. Dr. Federspiel is chief
bioengineer on a project to develop the Hattler Respiratory Catheter, an artificial lung designed to support damaged or
diseased lungs on a temporary basis during healing. The device is undergoing extensive testing in animal models and is
being developed commercially by a spin-off company, ALung Technologies Inc.
Late last year, Pittsburgh researchers partnered with U.S. Army scientists on a project to evaluate the merit of the device
for use in battlefield medicine - particularly as a possible treatment for lung injuries sustained in biochemical attacks. That
collaboration continues at the Brooke Army Medical Center in San Antonio, a major training center for combat physicians.
"The development of artificial organ systems is a vital part of what the McGowan Institute does," said Alan J. Russell,
Ph.D., director of the McGowan Institute for Regenerative Medicine. "Advances in research that are made in Pittsburgh
every day have the potential to affect lasting change on the future treatment of many disorders, including heart disease,
diabetes, Parkinson's disease, stroke, cystic fibrosis and muscular dystrophy."
Established by the University of Pittsburgh School of Medicine and the University of Pittsburgh Medical Center, the
McGowan Institute of Regenerative Medicine has a broad mission to develop a premier facility for clinical care, teaching
and research in regenerative medicine, including organ and tissue engineering, artificial organs and cellular and other
regenerative therapies.
The institute is named for the late William G. McGowan, founder of MCI Communications, who underwent a successful
heart transplant at the University of Pittsburgh Medical Center in 1987. He died in 1992.
Members of the American Society for Artificial Internal Organs represent more than 30 professional degree specialties
working in government or academic institutions and industry in more than 40 countries.
The mission of the International Society of Artificial Organs is to increase and encourage knowledge and research on
artificial organs, to facilitate the international exchange of knowledge, and to educate its members in the improvement
and optimal use of artificial organs.
To read more news releases about artificial organs, please visit the News Bureau Artificial Organs Archives.
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Copyright 2005 UPMC | Affiliated with the University of Pittsburgh Schools of the Health Sciences | Contact UPMC
Medical Textile Structures:
An Overview
Bhupender S. Gupta
From their first appearance as sutures more than 4000 years ago to their present
use in products ranging from gowns and wound dressings to arterial and skin grafts,
fibers and fabrics have been explored as potential materials for novel applications in
medicine and surgery. This continuous interest has its basis in the unique properties
of fibers—which in many respects resemble biological materials—and in their ability
to be converted into a wide array of desired end products.
Textile products for medical applications
include such materials as woven and knitted
polyester fabrics and PTFE felt and mesh.
Photo: IMPRA
This article will provide a brief introduction to polymer fibers, textiles, and related
structures used in medicine and will discuss the principles governing the performance
of these materials. Current product concerns and developmental activities will also
be reviewed.
Manufacturing Medical Fabrics Medical textile products are based on fabrics, of
which there are four types: woven, knitted, braided, and nonwoven (see Figure 1).
The first three of these are made from yarns, whereas the fourth can be made
directly from fibers, or even from polymers. (Gore-Tex—based products or
electrostatically spun materials from polyurethane are examples of products made
directly from polymers.) There is, therefore, a hierarchy of structure: the
performance of the final textile product is affected by the properties of polymers
whose structures are modified at between two and four different levels of
organization.
Figure 1. Constituent elements of medical textile
products.
Of the many different types of polymers, only a few can be made into useful fibers.
This is because a polymer must meet certain requirements before it can be
successfully and efficiently converted into a fibrous product. Some of the most
important of these requirements are:

Polymer chains should be linear, long, and flexible.
 Side groups should be simple, small, or polar.
 Polymers should be dissolvable or meltable for extrusion.
 Chains should be capable of being oriented and crystallized.
Common fiber-forming polymers include cellulosics (linen, cotton, rayon, acetate),
proteins (wool, silk), polyamides, polyester (PET), olefins, vinyls, acrylics,
polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), aramids (Kevlar,
Nomex), and polyurethanes (Lycra, Pellethane, Biomer). Each of these materials is
unique in chemical structure and potential properties. For example, among the
polyurethanes is an elastomeric material with high elongation and elastic recovery,
whose properties nearly match those of elastin tissue fibers. This material—when
extruded into fiber, fibrillar, or fabric form—derives its high elongation and elasticity
from alternating patterns of crystalline hard units and noncrystalline soft units.
Although several of the materials mentioned above are used in traditional textile as
well as medical applications, various polymeric materials—both absorbable and
nonabsorbable—have been developed specifically for use in medical products.
Chemical structures of some
of these materials are
illustrated in Figure 2.
Figure 2. Examples of fibrous materials developed for use in medicine.
The reactivity of tissues in contact with fibrous structures varies among materials
and is governed by both chemical and physical characteristics. Absorbable materials
typically excite greater tissue reaction, a result of the nature of the absorption
process itself. Among the available materials, some are absorbed faster (e.g.,
polyglycolic acid, polyglactin acid) and others more slowly (e.g., polyglyconate).
Semiabsorbable materials such as cotton and silk generally cause less reaction,
although the tissue response may continue for an extended time. Nonabsorbable
materials (e.g., nylon, polyester, polypropylene) tend to be inert and to provoke the
least reaction. To minimize tissue reaction, the use of catalysts and additives is
carefully controlled in medical-grade products.
Fibers. As discussed, of the many types of polymers, only a few can be made into
useful fibers that can then be converted into textile products. To make fibers,
polymers are extruded by wet, dry, or melt spinning and then processed to obtain
the desired texture, shape, and size. Through careful control of morphology, fibers
can be manufactured with a range of mechanical properties. Tensile strength can
vary from textile values (values needed for use in typical textile products such as
apparel) of 2—6 g/d (gram/denier) up to industrial values (values typical of industrial
products such as tire cords or belts) of 6—10 g/d. For high-performance applications,
such as body armor or structural composites, novel spinning techniques can produce
fibers with strengths approaching 30 g/d. Likewise, breaking extension can be varied
over a broad range, from 10—40% for textile to 1—15% for industrial and 100—
500% for elastomeric fibers.
Yarns. Fibers or filaments are converted into yarns by twisting or entangling
processes that improve strength, abrasion resistance, and handling. Yarn properties
(y) depend on those of the fibers or filaments (f) as well as on the angle of twist, .
Modulus (E ) and strength ( ) are reduced by the cos2 factor, while the extension
at break ( ) is increased by the sec2 factor:
Fabrics. Yarns are interlaced into fabrics by various mechanical processes—that is,
weaving, knitting, and braiding.1 The three prevalent fabric structures used for
medical implants or sutures are woven, in which two sets of yarns are interlaced at
right angles; knitted, in which loops of yarn are intermeshed; and braided, in which
three or more yarns cross one another in a diagonal pattern (see Figure 3). Knitted
fabrics can be either weft or warp knit, and braided products can include tubular
structures, with or without a core, as well as ribbon.
Figure 3. Examples of woven (top left), knitted (top right, bottom left), and braided
(bottom right) structures.
There are also numerous medical uses for nonwoven fabrics (wipes, sponges,
dressings, gowns), made directly from fibers that are needle-felted, hydroentangled,
or bonded through a thermal, chemical, or adhesive process. Nonwovens may also
be made directly from a polymer. For example, expanded polytetrafluoroethylene
(ePTFE) products such as sutures and arterial grafts and electrostatically spun
polyurethane used as tubular structures are examples of medical applications of
polymer-to-fabric nonwovens.2
Fabric Structures
The properties of fabrics depend on the characteristics of the constituent yarns or
fibers and on the geometry of the formed structure. Whether a fabric is woven,
knitted, braided, or nonwoven will affect its behavior.
Wovens. Fabrics that are woven are usually dimensionally very stable but less
extensible and porous than the other structures. One disadvantage of wovens is their
tendency to unravel at the edges when cut squarely or obliquely for implantation.
However, the stitching technique known as a Leno weave—in which two warp
threads twist around a weft—can substantially alleviate this fraying or unraveling
(see Figure 4).3
Figure 4. Fabric and vascular grafts made using a Leno
weave.
Knitted Fabrics. Compared with woven fabrics, weft-knitted structures are highly
extensible, but they are also dimensionally unstable unless additional yarns are used
to interlock the loops and reduce the extension while increasing elastic recovery.
Warp-knitted structures are extremely versatile, and can be engineered with a
variety of mechanical properties matching those of woven fabrics. The major
advantage of knitted materials is their flexibility and inherent ability to resist
unraveling when cut. A potential limitation of knitted fabrics is their high porosity,
which—unlike that of woven fabrics—cannot be reduced below a certain value
determined by the construction (see Figure 5). As a result, applications requiring
very low porosity usually incorporate woven materials.
Figure 5. Woven (left) and knitted (center and right) fabics used for vascular grafts,
showing differences in porosity.
Braided Structures. Typically employed in cords and sutures, braided structures
can be designed using several different patterns, either with or without a core.
Because the yarns criss-cross each other, braided materials are usually porous and
may imbibe fluids within the interstitial spaces between yarns or filaments. To reduce
their capillarity, braided materials are often treated with a biodegradable (polylactic
acid) or nonbiodegradable (Teflon) coating. Such coatings also serve to reduce
chatter or noise during body movement, improve hand or feel, and help position
suture knots that must be transported by pressure from a surgeon's finger from
outside the body to the wound itself.
Nonwovens. The properties of nonwoven fabrics are determined by those of the
constituent polymer or fiber and by the bonding process. For instance, expanded
PTFE products can be formed to meet varying porosity requirements. Because of the
expanded nature of their microstructure, these materials compress easily and then
expand—a suture, for example, can expand to fill the needle hole made in a tissue—
allowing for tissue ingrowth in applications such as arterial and patch grafts.
Polyurethane-based nonwovens produce a product that resembles collagenous
material in both structure and mechanical properties, particularly compliance
(extension per unit pressure or stress). The porosity of both PTFE- and polyurethanederived nonwovens can be effectively manipulated through control of the
manufacturing processes.
Textile Performance Principles
Textile materials for medical applications typically have specific performance
requirements relating to strength, stiffness, abrasion resistance, and mechanical
patency.
Strength. Among the many factors affecting a fabric's strength (fiber type,
molecular orientation, crystallinity) is the variability in properties—especially
elongation—of its constituent elements. Usually, the greater the variability in
elongation at break, the lesser the strength. Products requiring high strength (e.g.,
artificial ligaments) must incorporate elements whose properties range within a
narrow limit.
Stiffness. Bending stiffness—which governs the handling, comfort, and
conformability of a fabric—is a critical parameter in a number of medical applications.
A low value is usually desirable. For example, a suture with low bending stiffness
requires fewer throws to tie a secure knot and has higher knot strength. The most
important factors affecting bending stiffness are the shape of the fiber and the
modulus, linear density, and specific gravity of the material. Generally, the higher
the denier or the modulus or the lower the specific gravity, the higher the bending
stiffness. For example, polyester has a higher modulus than that of nylon, and will
result in a stiffer material. Polypropylene, with a lower density than nylon, should
have a higher stiffness, assuming all other factors are equal. In addition, a trilobal or
tubular structure produces a stiffer product than does a solid circular structure of the
same area or linear density.
Monofilament materials are much stiffer than multifilament. With all other factors
constant, the bending stiffness of a monofilament product such as a suture of denier
T will be roughly n times greater than a multifilament structure with n filaments of
denier T/n each. The use of multifilament yarns and/or fine-denier fibers in the yarn
produces a more flexible and supple end product. Knot efficiency—the ratio of the
tensile strength of knotted to unknotted thread—is affected by elongation at break
and bending stiffness. Most often, the greater the elongation, or the lower the
stiffness, the greater the knot efficiency.
Abrasion Resistance. Whenever fibers, yarns, or fabrics rub against themselves or
other structures, abrasion resistance assumes an important role. A high value is
usually desirable, especially in applications such as artificial ligaments or tendons.
The abrasion resistance of a yarn is influenced by several factors:
 The denier of the fiber (the lower the denier, the lower the resistance).
The amount of twist in the yarn that binds the fibers together (the lower the
twist, the lower the resistance).
 The orientation of molecules in the fibers (the higher the orientation, usually
the lower the resistance).
 The surface coefficient of friction (the higher the coefficient, the lower the
resistance).

Therefore, one can conclude that microdenier fibers, low-twist yarns, rough surfaces,
and highly oriented materials generally exhibit low abrasion resistance. However,
coating a bundle of fibers with a low-friction polymer can enhance its resistance to
abrasion.
Mechanical Patency. Implanted products that must bear loads over the long term
and maintain their dimensional integrity require a high degree of mechanical
patency—that is, the ability to resist permanent change in physical size, shape,
structure, and properties. The factors that contribute to mechanical patency include:


The chemical, biological, and stress environment into which the implant is
placed.
 The nonreactivity of the polymer with the environment.
 The size of the fibers.
The structure of the fabric (consolidated structures made of highly interlocked
woven material or warp knits provide an advantage).
 Perhaps most importantly, the viscoelastic properties of the material.
Thus, material selection is extremely critical for products—such as ligament
prostheses—that must continue to bear loads. The material specified must be able to
resist the elongation or growth that may occur as a result of stress relaxation during
each cycle of operation in the body. If no such material is available, then biological
tissues will need to be integrated into the assemblage to provide partial support of
the load and contribute to the product's long-term patency.
Current Medical Textile Research
The literature of the past decade, including patents, provides a broad overview of
current research activities as well as of some of the problems and concerns related
to implantable medical textiles. Among the more intensively studied product groups
are surgical sutures, vascular grafts, and artificial ligaments and tendons.
Surgical Sutures. For surgical sutures, the predominant areas of concern are
strength, capillarity, sliding and positioning of knots, knot security, and handling
characteristics. The recent focus of suture research has been on improving the
structure of the braids (two recently proposed products are spiral- and latticebraided materials),4 reducing the difference in the elongational properties between
the core and the sheath yarns, using finer-denier filaments in the sheath yarns, and
improving knot security and performance by exposing a two-throw square knot to
laser-beam energy. In a recently conducted experiment, it was shown that exposing
a two-throw square knot tied in a 3-0 Mersilene suture to energy from a CO2 laser
beam for a brief period of time not only made the knot fully secure but also led to an
increase in knot strength of appoximately 16% (see Figure 6).5
Figure 6. The effect on knot-breaking strength of exposing
a two-throw square knot tied in 3-0 Mersilene to energy
from a CO2 laser beam.
Vascular Grafts.Regarding vascular grafts, the lack of healing, compliance, and
suture-line patency continue to be concerns, especially in small-caliber (< 6 mm
diam) grafts.6 Three important efforts that highlight global developmental activities
in this area are:

The use of semiabsorbable structures, with absorbable components, woven or
knitted, in the inner tube wall.
 The use of spray technology in conjunction with elastomeric polymers to
produce collagen-like fiber structures with biomechanically compliant
properties.2
 The incorporation of elastomeric components in the weft threads of woven
prostheses.6 Using this technique, woven grafts of 4- to 6-mm diam could be
produced, with transverse compliance comparable to that of canine and other
similarly sized arteries.
Experiments with endothelial cell seeding7 and with coated grafts containing
albumin,8 gelatin,9 or collagen10 are also ongoing.
Ligaments and Tendons. Finally, in the area of artificial ligaments and tendons,
desirable properties include high strength, high elasticity, low abrasion, low creep,
and low stiffness. Current research endeavors are examining the use of ultra-highstrength fibers (e.g., Spectra from AlliedSignal), threads containing layers of both
absorbable inelastic and nonabsorbable elastic fibers, and coatings with
biocompatible polymers to reduce abrasion and restrict escape of abraded particles
from within the structure.11
Conclusion
Textile materials continue to serve an important function in the development of a
range of medical and surgical products. The introduction of new materials, the
improvement in production techniques and fiber properties, and the use of more
accurate and comprehensive testing have all had significant influence on advancing
fibers and fabrics for medical applications. As more is understood about medical
textiles, there is every reason to believe that a host of valuable and innovative
products will emerge.
References
1. Hatch KL, Textile Science, New York, West Publishing Co., pp 318—370, 1993.
2. Soldani G, Panol G, Sasken HF, et al., "Small-Diameter PolyurethanePolydimethylsiloxane Vascular Prostheses Made by a Spraying, Phase-Inversion
Process," J Mat Sci, Mat in Med, 3:106—113, 1992.
3. Kapadia I, and Ibrahim IM, Woven vascular grafts, U.S. Pat. 4,816,028, 1989.
4. Brennan KW, Skinner M, and Weaver G, Braided surgical sutures, U.S. Pat.
4,959,069, 1990.
5. Gupta BS, Milam BL, and Patty RR, "Use of Carbon Dioxide Lasers in Improving
Knot Security in Polyester Sutures," J App Biomat, 1:121—125, 1990.
6. Gupta BS, and Kasyanov VA, "Biomechanics of the Human Common Carotid Artery
and Design of Novel Hybrid Textile Compliant Vascular Grafts," J Biomed Mat Res,
34:341—349, 1997.
7. Williams SK, Carter T, Park PK, et al., "Formation of a Multilayer Cellular Lining on
a Polyurethane Vascular Graft Following Endothelial Cell Seeding," J Biomed Mat,
26(1):103—117, 1992.
8. Merhi Y, Roy R, Guidoin R, et al., "Cellular Reactions to Polyester Arterial
Prostheses Impregnated with Cross-Linked Albumin: In Vivo Studies in Mice,"
Biomat, 10(1): 56—58, 1989.
9 Bordenave L, Caix J, Basse-Cathalinat B, et al., "Experimental Evaluation of a
Gelatin-Coated Polyester Graft Used as an Arterial Substitute," Biomat, 10(3): 235—
242, 1989.
10. Guidoin R, Marceau D, Couture J, et al., "Collagen Coatings as Biological Sealants
for Textile Arterial Prostheses," Biomat, 10(3): 156—165, 1989.
11. Frey O, Dittes P, and Koch R, Prosthetic implant, U.S. Pat. 5,176,708, 1993.
Bhupender S. Gupta, PhD, received his undergraduate degree in textile technology
from the Punjab University, India, and his doctorate in textile physics from the
University of Manchester Institute of Science and Technology (Manchester, UK). He is
currently professor of textile materials science in the department of textile
engineering, chemistry, and science, College of Textiles, at North Carolina State
University (Raleigh, NC). His research interests include the physical and mechanical
properties of fibers, yarns, and fabrics; structural mechanics of assemblies;
absorbent nonwoven materials; and biomedical textiles.
Copyright ©1998 Medical Plastics and Biomaterials
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PubMed Central
Copyright © 2002, Texas Heart® Institute, Houston
Tex Heart Inst J. 2002; 29 (3): 229–230
Full Text
Early Clinical Application of Assisted Circulation
Domingo Liotta, MD
Figures/Tables
PDF
Dean, School of Medicine, MoRón University, Machado 914, Buenos Air
(1708), Argentina
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References
To the Editor:
Today, the implantation of ventricular assist devices (VADs) is a well-
established clinical procedure in its 2 applications: as a bridge to cardiac
transplantation and as a bridge to myocardial recovery. I thought that your
readers might enjoy an account of the earliest clinical applications of assis
circulation, as they occurred almost 4 decades ago.
In July 1961, I left my association with Dr. Willem J. Kolff, who was then
the Department of Artificial Organs at the Cleveland Clinic, and arrived at
Baylor University in Houston as a fellow in cardiovascular surgery.
Dr. Michael E. DeBakey knew of our group's presentation at the ASAIO
(American Society for Artificial Internal Organs) meeting in Atlantic City
March l961. At that meeting, I had described 1 the implantation, in dogs, o
types of orthotopic total artificial hearts, each of which used a different so
of external energy: an implantable electric motor; an implantable rotating
pump with an external electric motor; and a pneumatic pump. It was the 1
time that a driven pneumatic system had been described. Dr. DeBakey ask
me if I would agree to spend some time in the laboratory working on the t
artificial heart project during my fellowship. At that time, there was nothin
Baylor to start with, except for Louis Feldman's enthusiasm. He was the
engineer in charge of the machine shop.
In those days, cases of post-cardiotomy cardiogenic shock, with stunning o
potentially viable myocardial tissue, were not uncommon. Shortly after m
arrival at Baylor, a cardiac surgery patient had to be supported for several
hours postoperatively by means of a left ventricular bypass from the left
atrium to the femoral artery with the aid of a roller pump. This short perio
support had been unsuccessful, so it occurred to me, while I walked back t
Baylor one evening in the fall of 1961, that a prolonged use (several days)
mechanical circulation might be the answer to support these patients. Duri
1961–62, our lab at Baylor developed a small, intrathoracic, pneumatic-dr
pump that partly bypassed the left ventricle from the left atrium to the thor
aorta. The pump's housing was made of Silastic reinforced with Dacron fa
(Fig. 1). 2,3 In May 1962, I presented this work at the Young Investigator's
Award Competition of the American College of Cardiology, in Denver.
On 18 July 1963, one of Dr. E. Stanley Crawford's patients underwent an
aortic valve replacement. The calcified stenotic valve was replaced with a
Starr-Edwards prosthetic valve. Early the next morning, the patient had a
cardiac arrest and was resuscitated by means of the open-chest technique.
After the chest was closed, it was evident that severe brain damage had
occurred. The patient remained in a coma, with low cardiac output and anu
Subsequently, a rather severe pulmonary edema developed and was refrac
to standard treatment.
The 1st clinical VAD, bypassing the left ventricle from the left atrium to t
descending aorta through a left thoracotomy, was implanted in this patient
the evening of 19 July by Dr. Crawford and me. The pump was regulated
bypass with 1,800 to 2,500 mL of blood per minute. Although the anuria t
had been present since cardiac arrest persisted, the pulmonary edema clear
as indicated by plain chest x–ray and auscultation. We discontinued
mechanical support after 4 days of continuous use, but the patient remaine
a coma and died. 4
At the beginning of 1966, Dr. DeBakey and I started implanting paracorpo
VADs at the Methodist Hospital. A patient from Mexico underwent a dou
valve replacement but could not be weaned from extracorporeal circulatio
Then we implanted a paracorporeal VAD from the left atrium to the right
subclavian artery. After support by the VAD for 10 days, at a flow rate up
1,200 mL/min, the patient recovered, which made this the 1st successful u
of a VAD for postcardiotomy shock. 5,6 Several years later, she died in
Mexico in a car accident.
The 1966 paracorporeal VADs were lined with Dacron velour to create a
neoendocardium that would deter thromboembolism. 7 Everything that
followed this early clinical research in the field of assisted circulation is w
known and need not be repeated here.
Top
References
References
1. Liotta D, Taliani T, Giffoniello AH, Sarria Deheza F, Liotta S,
Lizarraga R, et al. Artificial heart in the chest: Preliminary report.
Trans Am Soc Artif Intern Organs 1961;7:318–22.
2. Liotta D, Taliani T, Giffoniello AH, Liotta S, Lizarraga R, Tolocka
Pagano J. Ablation experimentale et replacement du coeur par un
coeur artificial intra-thoracique [in French]. Lyon Chirurgical
1961;57:704.
3. Liotta D, Crawford ES, Cooley DA, DeBakey ME, Urquia M,
Feldman L. Prolonged partial left ventricular bypass by means of a
intrathoracic pump implanted in the left chest. Trans Am Soc Artif
Intern Organs 1962;8:90–9.
4. Liotta D, Hall CW, Henly WS, Beall AC, Cooley DA, DeBakey M
Prolonged assisted circulation after cardiac or aortic surgery.
Prolonged partial left ventricular bypass by means of intracorporea
circulation. Denver, May 1962. Am J Cardiol 1963;12:399–405. [T
paper was a finalist in the Young Investigator's Award Competitio
the American College of Cardiology.]
5. DeBakey ME, Liotta D, Hall CW. Left-heart bypass using an
implantable blood pump. In: Mechanical devices to assist the failin
heart. Proceedings of the National Research Council (U.S.).
Committee on Trauma; 1964 Sep 9–10; Washington, DC. Washing
DC: National Academy of Sciences-National Research Council; 19
p. 223–39.
6. DeBakey ME. Left ventricular bypass pump for cardiac assistance
Clinical experience. Am J Cardiol 1971;27:3–11. [PubMed]
7. Liotta D, Hall CW, Akers WW, Villanueva A, O'Neal RM, DeBak
ME. A pseudoendocardium for implantable blood pumps. Trans A
Soc Artif Intern Organs 1966;12:129–34. [PubMed]
Figures and Tables
Fig. 1 Drawing of the 19 July 1963 clinical prototype that
was developed by Domingo Liotta at Baylor University,
Houston. The pump is shown in diastole. The actual clinic
prototype is at the Smithsonian Institution, Washington, D
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Abstract
In some embodiments, prosthetic conduits include biocompatible material formed into a
generally cylindrical section and an expanded section connected to the generally
cylindrical section to form a conduit. The conduit has a lumen extending through the
generally cylindrical section and the expanded section. In some embodiments, the
biocompatible material is tissue. The biocompatible material can include one segment or
a plurality of segments joined together to form the generally cylindrical section and the
expanded section. In some embodiments, the prosthetic conduit includes a reinforcement
to prevent unwanted dilation or collapse of the conduit. The reinforcement can be placed
at or near the junction of a generally cylindrical section and an expanded section and/or at
other locations along the conduit. The prosthetic conduit may or may not include a
prosthetic heart valve. The prosthetic conduit can include tubules to facilitate attachment
of coronary arteries to the prosthetic conduit for embodiments in which a portion of the
aorta adjacent the heart is replaced. In some embodiments, the prosthetic conduit includes
two sections that are joined to form the prosthetic conduit.
Inventors:
Holmberg, William R.; (New Richmond, WI) ; Peredo, Mario Osvaldo
Vrandecic; (Belo Horizonte, BR)
Correspondence ALTERA LAW GROUP, LLC
Name and
6500 CITY WEST PARKWAY
Address:
SUITE 100
MINNEAPOLIS
MN
55344-7704
US
Serial No.:
056774
Series Code:
10
Filed:
January 24, 2002
623/1.31; 623/1.26
U.S. Current Class:
623/1.31; 623/1.26
U.S. Class at Publication:
A61F 002/06
Intern'l Class:
Claims
What we claim is:
1. A prosthesis comprising a reinforcement element and a prosthetic conduit comprising
biocompatible material, the prosthetic conduit having a generally cylindrical section and
an expanded section extending from the generally cylindrical section, wherein the
reinforcement element at the junction between the generally cylindrical section and the
expanded section.
2. The prosthesis of claim 1 wherein the biocompatible material comprises tissue.
3. The prosthesis of claim 2 wherein the tissue comprises pericardium, submucosa or
dura mater.
4. The prosthesis of claim 2 wherein the tissue comprises porcine, ovine, equine or
bovine tissue.
5. The prosthesis of claim 2 wherein the tissue comprises crosslinked tissue.
6. The prosthesis of claim 5 wherein the tissue is crosslinked with glutaraldehyde or
triglycidylamine.
7. The prosthesis of claim 1 wherein the biocompatible material comprises at least two
segments joined to form the conduit.
8. The prosthesis of claim 7 wherein one segment forms the generally cylindrical section
and a portion of the expanded section.
9. The prosthesis of claim 1 wherein the biocompatible material comprises a single
segment.
10. The prosthesis of claim 1 wherein the expanded section has a maximum diameter at
least about 10% larger than the average diameter of the generally cylindrical section.
11. The prosthesis of claim 1 wherein the expanded section has a maximum diameter
from about 12% to about 20% larger than the average diameter of the generally
cylindrical section.
12. The prosthesis of claim 1 wherein the expanded section has scallops along its free
edge for attachment around a native aortic heart valve.
13. The prosthesis of claim 1 further comprising a prosthetic valve connected to the
expanded section.
14. The prosthesis of claim 13 wherein the prosthetic valve comprises a rigid leaflet
connected to an orifice ring.
15. The prosthesis of claim 13 wherein the prosthetic valve comprises tissue leaflets.
16. The prosthesis of claim 13 wherein the prosthetic valve comprises flexible polymer
leaflets.
17. The prosthesis of claim 1 wherein the expanded section comprises tubules positioned
for the attachment of the right and left coronary arteries.
18. The prosthesis of claim 1 wherein the expanded section has two components that
connect together to complete the formation of the expanded section.
19. The prosthesis of claim 1 wherein the reinforcement element is a ring.
20. The prosthesis of claim 1 wherein the reinforcement element comprises tissue.
21. The prosthesis of claim 1 wherein the reinforcement element comprises a polymer.
22. The prosthesis of claim 21 wherein the polymer is woven into a fabric.
23. The prosthesis of claim 1 wherein the reinforcement element comprises metal.
24. The prosthesis of claim 1 wherein the reinforcement element is a band of
pericardium.
25. The prosthesis of claim 1 wherein the reinforcement element is a roll of tissue.
26. The prosthesis of claim 1 wherein the reinforcement element surrounds the
circumference of the biocompatible material.
27. The prosthesis of claim 1 wherein the reinforcement element surrounds only a portion
of the circumference of the biocompatible material.
28. The prosthesis of claim 1 wherein the prosthetic conduit has a reinforcement near the
inflow edge.
29. The prosthesis of claim 1 wherein the prosthetic conduit has a reinforcement near the
outflow edge.
30. A prosthesis comprising a biocompatible material formed into a generally cylindrical
section and an expanded section extending from the generally cylindrical section, the
expanded section including tubules connecting the central lumen of the expanded section
to an external opening.
31. The prosthesis of claim 30 wherein the tubules are positioned for the attachment of
the right and left coronary arteries.
32. The prosthesis of claim 30 wherein the biocompatible material comprises at least two
sections of material that join together to form the generally cylindrical section and the
expanded section.
33. The prosthesis of claim 30 further comprising a prosthetic heart valve.
34. The prosthesis of claim 33 wherein the prosthetic heart valve is a stentless valve with
flexible leaflets and a leaflet support structure that is positioned to avoid blockage of the
tubules.
35. The prosthesis of claim 30 wherein the biocompatible material comprises tissue.
36. A prosthesis comprising biocompatible material formed into a generally cylindrical
section and an expanded section connected to the generally cylindrical section to form a
conduit with a lumen extending through the generally cylindrical section and the
expanded section, the free edge of the expanded section having scallops that fit ajacent to
and downstream from the commissures of a native heart valve.
37. The prosthesis of claim 36 wherein the biocompatible material comprises tissue.
38. The prosthesis of claim 36 further comprising a prosthetic valve attached to the
biocompatible material.
39. A prosthesis comprising a reinforcement element, a prosthetic conduit comprising
biocompatible material and a prosthetic valve attached to the prosthetic conduit, wherein
the reinforcement element is attached to the prosthetic conduit downstream from the
prosthetic valve to inhibit dilation of the conduit and to promote proper valve function.
40. The prosthesis of claim 39 wherein the prosthetic conduit comprises a generally
cylindrical section and an expanded section extending from the generally cylindrical
section, wherein the reinforcement element is positioned at the junction between the
generally cylindrical section and the expanded section.
41. The prosthesis of claim 39 wherein the prosthesis further comprises a reinforcement
near the inflow edge.
42. A prosthesis comprising a first prosthetic conduit section and a second prosthetic
conduit section wherein the inflow edge of the first prosthetic conduit section is
configured for attachment to the outflow edge of the second prosthetic conduit section,
the first prosthetic conduit section having a generally cylindrical section and the second
prosthetic conduit section comprising a prosthetic valve.
43. The prosthesis of claim 42 wherein the second conduit section has an expanded
section having a maximum diameter at least about 10% greater than the average diameter
of the generally cylindrical section.
44. The prosthesis of claim 42 wherein the prosthetic valve is a mechanical valve.
45. The prosthesis of claim 44 wherein the second conduit section has an expanded
section with a generally spherical shape over a portion of a sphere.
46. The prosthesis of claim 42 wherein the prosthetic valve has flexible leaflets.
47. The prosthesis of claim 46 wherein the second conduit section has an expanded
section with three lobes.
48. A prosthesis comprising a reinforcement element and a prosthetic conduit comprising
biocompatible material, wherein the reinforcement element is attached to the prosthetic
conduit proximate to the outflow edge.
49. The prosthesis of claim 48 further comprising a prosthetic valve attached to the
prosthetic conduit.
50. A prosthesis comprising a reinforcement element, a prosthetic conduit comprising
biocompatible material and a prosthetic valve attached to the prosthetic conduit, wherein
the reinforcement element is attached to the prosthetic conduit proximate to the inflow
edge.
Description
FIELD OF THE INVENTION
[0001] The invention relates to prostheses for the replacement of blood vessels and,
optionally, valve, especially at or near a heart valve. More specifically, the invention
relates to prostheses for aorta or pulmonary artery replacement, particularly at, adjacent
and/or proximal the respective aortic or pulmonary heart valve. The prostheses may
include a valve, such as a heart valve.
BACKGROUND OF THE INVENTION
[0002] Physicians use a variety of prostheses to correct problems associated with the
cardiovascular system, especially the heart. For example, the ability to replace or repair
diseased heart valves with prosthetic devices has provided surgeons with a method of
treating heart valve deficiencies due to disease and congenital defects. A typical
procedure involves removal of the native valve and surgical replacement with a prosthetic
heart valve.
[0003] Prosthetic heart valve leaflets or occluders perform the function of opening and
closing to regulate the blood flow through the heart valve. Typically, heart valve leaflets
must either pivot or flex with each cycle of the heart to open and close the valve. Heart
valves function as check valves, which open for flow in one direction and close in
response to pressure differentials to limit reverse flow.
[0004] Aortic and pulmonary heart valves are positioned at the connection of arteries to
the left and right heart ventricles, respectively. Replacement or repair of these valves may
involve disconnecting and reconnecting the corresponding artery. This process can
involve the replacement of a portion of the artery adjacent the valve with a prosthetic
conduit. In addition, it may be desirable to replace the portion of the artery adjacent the
valve due to degeneration of the artery even if there is no damage to the valve. Whether
or not the heart valve is replaced along with the portion of the artery adjacent the heart
valve, the procedure for replacing the artery should not interfere with valve function.
[0005] Both the natural aorta and the pulmonary artery have slightly dilated portions
adjacent the heart valves called Sinuses of Valsalva. The natural sinuses of the aorta are
somewhat larger than the sinuses of the pulmonary artery. The aorta adjacent the aortic
heart valve is connected to coronary arteries that provide aerated blood to the heart
muscle. Replacement of this portion of the aorta involves reconnection of the coronary
arteries.
SUMMARY OF THE INVENTION
[0006] In a first aspect, the invention pertains to a prosthesis including a reinforcement
element and a prosthetic conduit including biocompatible material. The prosthetic
conduit includes a generally cylindrical section and an expanded section extending from
the generally cylindrical section. Generally, the reinforcement element overlaps the
junction between the generally cylindrical section and the expanded section. In some
embodiments, the prosthetic conduit also has a reinforcement at the inflow edge and/or
the outflow edge.
[0007] In another aspect, the invention pertains to a prosthesis including biocompatible
material formed into a generally cylindrical section and an expanded section extending
from the generally cylindrical section. The expanded section includes tubules connecting
the central lumen of the expanded section to an external opening.
[0008] In an additional aspect, the invention pertains to a prosthesis comprising
biocompatible material formed into a generally cylindrical section and an expanded
section connected to the generally cylindrical section, forming a conduit. The conduit has
a lumen extending through the generally cylindrical section and the expanded section.
The biocompatible material can be a single segment or a plurality of segments that are
joined to form the conduit. The free edge of the expanded section has scallops that fit
adjacent to and downstream from the commissures of a native heart valve.
[0009] In a further aspect, the invention pertains to a prosthesis including a reinforcement
element, a prosthetic conduit comprising biocompatible material and a prosthetic valve.
The reinforcement element is attached to the prosthetic conduit downstream from the
prosthetic valve to inhibit dilation of the conduit and promote proper function of the
valve.
[0010] Furthermore, the invention pertains to a prosthetic system comprising a first
prosthetic conduit section and a second prosthetic conduit section. The inflow edge of the
first prosthetic conduit section is configured for attachment to the outflow edge of the
second prosthetic conduit section. The first prosthetic conduit section has a generally
cylindrical section, and the second prosthetic conduit section includes a prosthetic valve.
[0011] In addition, the invention pertains to a prosthesis comprising a reinforcement
element and a prosthetic conduit. The prosthetic conduit comprises biocompatible
material. The prosthesis can further comprise a prosthetic valve in some embodiments.
The reinforcement element is attached to the prosthetic conduit proximate to the outflow
edge.
[0012] In an additional aspect, the invention pertains to a prosthesis comprising a
reinforcement element, a prosthetic conduit comprising biocompatible material and a
prosthetic valve attached to the prosthetic conduit. The reinforcement element is attached
to the prosthetic conduit proximate to the inflow edge.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a side perspective view of a biological conduit with an expanded section
corresponding to sinuses of Valsalva.
[0014] FIG. 2 is a side perspective view of a biological conduit with an expanded section
with a scalloped edge.
[0015] FIG. 3 is a side perspective view of a biological conduit with an expanded section
with tubules for the attachment of coronary arteries.
[0016] FIG. 4 is an end view of the biological conduit of FIG. 3.
[0017] FIG. 5 is a sectional view of the biological conduit of FIG. 3 taken along line 5-5
of FIG. 3.
[0018] FIG. 6 is a perspective view of a mechanical heart valve prosthesis.
[0019] FIG. 7 is a perspective view of a stentless heart valve prosthesis.
[0020] FIG. 8 is a perspective view of a stented heart valve prosthesis with flexible
leaflets.
[0021] FIG. 9 is a cut-away perspective view of a prosthetic conduit with a portion of the
conduit removed to expose a prosthetic valve.
[0022] FIG. 10 is a cut-away perspective view of a prosthetic conduit with tubules for
attachment of coronary arteries, with a portion of the conduit removed to expose a
prosthetic valve.
[0023] FIG. 11 is a cut-away perspective view of a two-piece prosthetic conduit, with a
portion of the expanded section of the conduit removed to expose a prosthetic valve.
[0024] FIG. 12 is a perspective view of a prosthetic conduit having a reinforcement near
a prosthetic valve to resist dilation of the conduit downstream from the valve, with the
valve shown schematically in phantom lines.
[0025] FIG. 13 is a perspective view of a prosthetic conduit having a reinforcement near
the outflow edge, with a prosthetic valve shown schematically in phantom lines.
[0026] FIG. 14 is a top view of a cut sheet of material for formation into a prosthetic
conduit with an expanded section at a location corresponding to sinuses of Valsalva.
[0027] FIG. 15 is a side view of a mandrel for the formation of a sheet of material into a
prosthetic conduit with an expanded section at a location which would correspond to
sinuses of Valsalva.
[0028] FIG. 16 is a top view of a sheet of material cut with straight edges for formation
into a prosthetic conduit with an expanded section at a location which would correspond
to sinuses of Valsalva.
[0029] FIG. 17 is a top view of two sheets of material for formation into a two section
prosthetic conduit having an expanded section.
[0030] FIG. 18 is a top view of a leaflet for formation into a prosthetic valve.
[0031] FIG. 19 is a top view of three leaflets of FIG. 18 joined together.
[0032] FIG. 20 is a top view of three leaflets joined to a section of material to form a
structure that can be contoured to form a prosthetic conduit with a prosthetic valve having
flexible leaflets in which the prosthetic conduit has an expanded section.
[0033] FIG. 21 is a top view of a sheet of tissue cut to include leaflets sections that can be
folded into position along the prosthetic conduit.
[0034] FIG. 22 is a top view of a sheet of sheet of tissue for a prosthetic conduit with cut
leaflet sections attached.
DETAILED DESCRIPTION OF THE INVENTION
[0035] Improved prosthetic conduits may include structures with an expanded section at
locations corresponding with sinus structures of arteries near the attachment to the heart.
The expanded section reflects the expanded character of the natural sinuses, but may or
may not have a similar shape as the natural sinuses. The inclusion of the expanded
section is particularly appropriate when the native sinuses are removed. To maintain
proper coaptation of the valve, the prosthetic conduit can include a reinforcement
between the expanded section and an adjacent unexpanded section to inhibit unwanted
dilation at the intersection of the two sections, such that the coaptation of the leaflets is
maintained. Similarly, reinforcements can be located at the inflow edge to help to
maintain valve function. Reinforcements can be advantageously used adjacent prosthetic
valves even in embodiments in which the prosthetic conduit does not have an expanded
section, for example, if the native sinuses are not removed. The presence of an expanded
section analogous to the natural sinuses facilitates the reattachment of the coronary
arteries to an aortic prosthesis. In additional embodiments, the conduit includes specific
structure that provides for simplified attachment of the coronary arteries to the conduit. In
general, the improved prosthetic conduits, especially those with reinforcements, can be
particularly advantageous when native heart valves are replaced with prosthetic valves
without a stent. The conduit may or may not include a heart valve as part of the conduit.
[0036] Damaged or diseased natural heart valves can be replaced with prosthetic valves
to restore valve function. The aortic heart valve and the pulmonary heart valve are
located at the points of connection between the heart and arteries, the aorta and the
pulmonary artery, respectively. During the replacement of the aortic heart valve and/or
the pulmonary heart valve, a portion of prosthetic conduit can be used to replace a portion
of the respective arteries. Furthermore, a portion of the arteries can be replaced as part of
a procedure to repair the heart valves. In addition, a portion of the arteries can be replaced
adjacent the heart due to disease or damage of the artery to reconstruct the artery without
repairing or replacing the valve. The patient can be an animal, especially a mammal, and
preferably is a human.
[0037] Mechanical heart valve prostheses can have leaflets formed from a rigid material
that pivot to open and close the valve. Mechanical valves generally have an orifice ring
that forms the valve lumen with one or more leaflets attached to the orifice ring.
Alternatively, the heart valve prostheses can have flexible leaflets that flex to open and
close the valves. Flexible leaflets can be formed from tissue or flexible polymers.
[0038] In a prosthetic valve with flexible leaflets, the leaflets are supported by a support
structure that includes commissure supports and scallops between the commissure
supports. In some embodiments, the support structure includes a rigid component that
maintains the leaflet function of the valve against the forces opening and closing the
valve. Valves with a rigid support structure are termed stented valves, and the rigid
support is called a stent. The stent provides a scaffolding for the leaflets. The stent
generally is sufficiently rigid such that only the base of the stent is attached to the patient
or other device.
[0039] In alternative embodiments, the support structure is not sufficiently rigid to
maintain the leaflet function of the valve against the forces opening and closing the valve.
In these embodiments, the valve is termed stentless. In a stentless valve, the support
structure also has commissure supports at which the free edge of the leaflets connect with
the support structure, and scallops which support the attached edge of the leaflets.
However, in the stentless valve, the support structure is less rigid such that both edges of
the support structure, i.e., the inflow edge and the outflow edge, must be secured, such as
by suturing or other fastening approach, to other anatomical structures, such as the wall
of a blood vessel, or to other device structures, such as a prosthetic conduit, to prevent the
valve from collapsing against the fluid pressure. The prosthesis, especially a stentless
prosthesis, can also have scallops along the inflow edge to approximately match the
native annulus following removal of the native leaflets.
[0040] Regardless of the particular design, valve leaflets are configured to open and close
in response to changes in blood flow. In particular, the leaflets function as one way check
valves that open to allow flow in a desired direction and close in response to pressure
differentials to limit reverse flow. Thus, when blood is flowing downstream, the leaflets
fully open to allow for flow through the valve. The leaflets correspondingly close to
inhibit flow upstream. For the aortic and pulmonary valves, the valves open for flow from
the heart into the arteries and close to resist flow back from the arteries into the heart.
[0041] The conduit prostheses described herein can be used for the replacement of the
aorta adjacent the heart or the pulmonary artery adjacent the heart. Prostheses for
replacement of the pulmonary artery do not attach to coronary arteries or the equivalent
thereof. Thus, the prostheses for the replacement of pulmonary arteries are
correspondingly simpler than the prostheses for the replacement of the section of the
aorta.
[0042] The aorta and pulmonary artery have a small dilated section with three sinuses
adjacent the attachment site to the heart. The dilated sections of the aorta and pulmonary
artery are termed the sinuses of Valsalva. The sinuses extend between the commissures of
the valve. Thus, the native valve is located within the sinuses section of the artery. The
sinuses provide space for the opening of the leaflets and, in the case of the aorta, for
attachment of the coronary arteries. Downstream, the sinuses connect to an undialated
portion of the respective arteries, the pulmonary artery or the ascending aorta.
[0043] For the aorta, two coronary arteries, the left coronary artery and the right coronary
artery, attach to the sinuses. These arteries provide the blood flow to the heart muscle.
Sufficient blood flow to the heart muscle is necessary for heart function. In a native aorta,
the coronary arteries are positioned to avoid the natural commissures supporting the
native leaflets of a native aortic valve. Replacement of the valve and/or the adjacent
section of the aorta should provide for maintaining flow from the aorta into the coronary
arteries.
[0044] In embodiments of particular interest, the prosthetic conduit includes an expanded
section corresponding to the location of the natural sinuses of Valsalva. The prosthetic
conduit further includes a generally cylindrical section extending from the expanded
section. In some embodiments, a reinforcement is placed at or near the connection
between the expanded section and the generally cylindrical section. The presence of the
expanded section can provide for structure near the heart valve that is more similar to
native structure and function.
[0045] A reinforcement, in general, can prevent undesirable dilation whether or not the
prosthetic conduit includes an expanded section. Suitable reinforcements generally are
positioned at the inflow edge, downstream from the valve at the top of commissure
supports and/or at the outflow edge. If an expanded section is present, a downstream
reinforcement generally is placed at or near the junction of the expanded section and the
generally cylindrical section. To provide an appropriate level of reinforcement, the
reinforcement generally encircles the circumference of the prosthetic conduit, although
the reinforcement can encircle a significant fraction of the circumference with one or
several disconnected sections rather than the entire circumference.
[0046] Replacement of the aorta or pulmonary artery or portions thereof may also involve
replacement of the heart valve. If the heart valve is also replaced, the valve and section of
aorta or pulmonary artery can be replaced as a single unit or as two components.
Mechanical prosthetic valves generally have a low profile such that the orientation of the
valve with respect to the coronary arteries is not significant. However, valves with
flexible leaflets have a higher profile such that the support structure has to be positioned
with the commissure supports oriented to avoid blocking the coronary arteries. The
structure of the prosthetic conduit can be designed to facilitate orientation of the
prosthetic valve by including structure and/or markings that indicate the valve orientation
within the prosthesis.
[0047] The coronary arteries may or may not be disconnected from the aorta when a
section of aorta near the heart, i.e., the ascending aorta, is removed for replacement.
Specifically, the aorta can be severed along the sinuses, leaving the coronary arteries
intact along a portion of the sinuses at the attachment to the native heart valve. The
prosthetic conduit can be shaped to attach to the remaining portion of the sinuses while
avoiding the coronary arteries. Alternatively, the aorta can be severed along the scallops
of the valve such that the coronary arteries are disconnected from the valve. In further
embodiments, the prosthetic conduit can replace the entire aorta adjacent the heart such
that the coronary arteries are attached to the conduit. The presence of the expanded
section facilitates attachment of the prosthetic conduit in the aortic position with the
coronary arteries. Since the coronary arteries are positioned for attachment to the natural
sinuses, the presence of prosthetic sinuses can involve reattachments taking into account
the natural positioning of the coronary arteries.
[0048] If the corresponding heart valve is not replaced, the end of the prosthetic conduit
can be shaped to attach to the section of the sinuses that is not removed. For the aorta, the
expanded section of the prosthesis should be attached to account for the presence of the
coronary arteries. Even though the aorta can be cut along the sinuses while leaving the
coronary arteries intact, it may be desirable to cut the sinuses along the scallops of the
valve, in which case, the coronary arteries would be disconnected from the remaining
sections of the aorta.
[0049] In other embodiments, the heart valve prosthesis is replaced along with a portion
of the artery while leaving the natural sinuses or a portion thereof intact. For the aorta, the
prosthetic valve can be implanted following removal of the native leaflets while leaving
the coronary arteries and the corresponding section of the aorta intact. In these
embodiments, the section of the prosthetic conduit can have the same conduit structure
with an expanded section as the embodiments in which the aortic heart valve is not
replaced. The heart valve can be replaced with a prosthetic valve with flexible leaflets
that is parachuted down the remaining section of artery. The aortic valve is positioned
with the proper location and orientation relative to the attached coronary arteries.
[0050] In additional embodiments, the entire artery adjacent the heart is removed. The
native heart valve is also removed and replaced with a prosthetic valve. In these
embodiments, for the aorta, the coronary arteries are attached to the prosthetic conduit. If
the prosthetic valve is a mechanical valve with a typical low profile, the orientation of the
valve relative to the placement of the coronary arteries generally is not as important since
the coronary arteries are generally connected to the conduit far enough away from the
valve that the valve structure does not block flow into the coronary arteries. If the
orientation of the mechanical valve is significant, the valve can be oriented with
markings, as appropriate, to guide the implantation. For prosthetic aortic valves with
flexible leaflets, the orientation of the valve is significant to avoid blocking flow into the
coronary arteries with the commissure supports.
[0051] If the portion of artery adjacent the heart is replaced along with the corresponding
heart valve, the prosthesis can be formed as a single unit with the valve attached to the
conduit. This single unit should provide for the attachment of the coronary arteries. In
some of these embodiments, generally embodiments with mechanical valves, the
coronary arteries can be attached at selected locations during implantation by the surgeon
by forming small holes in the conduit and connecting the arteries to an appropriately
placed hole. The conduit can include markings to facilitate orientation of the conduit and
valve as well as for proper placement of the coronary arteries for the aorta. Alternatively,
the conduit can include tubules that extend from the conduit for attachment of the
coronary arteries. Since the prosthesis is formed as a unit, the tubules can be positioned
during assembly to avoid the support structure of the leaflets as well as for appropriate
positioning for the attachment of the coronary arteries. The prosthesis can be oriented for
implantation by orienting the tubules for convenient attachment of the coronary arteries.
[0052] In alternative embodiments, the prosthesis includes two components that
interconnect to complete the replacement of the removed native tissue. One
interconnecting component of the complete prosthesis, the conduit component, is a
prosthetic conduit. The second interconnecting component, the valved component,
includes the prosthetic heart valve along with the portion of the prosthetic conduit
surrounding the valve. Since the component is formed with the valve already attached to
the portion of conduit, the implantation involves attachment of the valved component to
the heart. The interconnecting components generally are designed to provide for the
attachment of the coronary arteries, especially for prosthetic valves with flexible leaflets.
For example, the coronary arteries can be attached to appropriately placed holes in the
side of the conduit between the commissure supports. Alternatively, the conduit can
include tubules for the attachment of the coronary arteries. The conduit component and
the valved component fit together to complete the prosthesis with appropriate orientation
of the components to account for the positioning and attachment of the coronary arteries.
[0053] Approaches used to form the various components can be selected based on the
type of material being used. Specifically, tissue components can be assembled from
sections of tissue to have the particular shape. Sheets of tissue or other biocompatible
material can be shaped and fastened in a particular tubular form of the conduit structure.
The prosthetic heart valves generally can be formed separately and then attached to a
conduit section, if appropriate, when the conduit section is being shaped into the tubular
form. Alternatively, the valve components can be assembled as an integral part of the
conduit when forming the overall prosthesis.
[0054] Having an expanded portion in the conduit provides for functioning of the heart
valve more similarly to the native structure than with prosthetic conduits without an
expanded section. Natural sinuses can provide an increased valve lumen and pressure
differentiation at the valve. For the aorta, the expanded portion simplifies the attachment
of the coronary arteries since the expanded portion extends outward to mimic native
sinuses. In contrast, in embodiments without the expanded portion, the coronary arteries
are positioned to compensate for the extra distance to a generally cylindrical conduit
section. A reinforcement at appropriate positions along the prosthetic conduit can prevent
or limit the expansion of the prosthetic conduit and the corresponding deformation of the
valve.
[0055] In embodiments with a prosthetic valve, the prosthesis can provide for simplified
attachment of both the valve and the conduit. In particular, the prostheses are designed
for convenient attachment of the coronary arteries while simultaneously accounting for
the positioning of commissure supports for valves with flexible leaflets. If the portion of
the aorta adjacent the heart is replaced, forms of attachment along the expanded section
to tubules or to holes in the conduit can be used to facilitate reattachment of the coronary
arteries without interference from the support structure of the valve, especially if the
valve has flexible leaflets. Due to these improved features, the surgical times can be
reduced so that the patient's time on a by-pass machine can be correspondingly reduced.
[0056] Prosthetic Conduits
[0057] The prostheses described herein generally include a prosthetic conduit for the
replacement of a portion of the aorta or the pulmonary artery adjacent or near the heart.
The prostheses may or may not include a prosthetic valve. Prostheses that include a
prosthetic valve are described further below. Prosthetic conduits can be used when the
heart valve is separately replaced with a portion of the aorta or pulmonary artery adjacent
the valve remaining intact. In preferred embodiments, the prosthetic conduit has an
expanded section corresponding to the sinuses of the native aorta or pulmonary artery.
However, some of the features for attachment of coronary arteries can be incorporated
into improved prosthetic conduits without an expanded section. In some embodiments,
the conduit includes tubules for the attachment of the coronary arteries to the conduit to
provide fluid communication between the interior of the conduit and the coronary
arteries.
[0058] Referring to FIG. 1, an embodiment of a prosthetic conduit is shown. Prosthetic
conduit 100 includes a generally cylindrical section 102 and an expanded section 104. In
some embodiments, prosthetic conduit 100 has an optional reinforcement 106 at or near
junction 108 of cylindrical section 102 and expanded section 104. Prosthetic conduit 100
can optionally include a sewing ring 110 and/or a reinforcement. In general in the
embodiments herein, sewing rings may or may not be included at the inflow and outflow
edges of the prosthetic conduits. If formed appropriately, the sewing ring may also
provide reinforcement of the prosthetic conduit. However, the sewing ring may not be
present, or the sewing ring may not provide significant reinforcement of the conduit.
Thus, a separate reinforcement with the properties described herein can be added at the
outflow and/or inflow edges of the conduit, optionally along with reinforcements in other
locations along the conduit, such as optional reinforcement 106 of FIG. 1.
[0059] Prosthetic conduits generally can be formed in a range of sizes to accommodate a
particular patient. For example, the prosthetic conduit could be produced in a series of
sizes, such as six sizes or more than six sizes, such that the physician can select one of the
sizes for implantation. Pulmonary prosthetic conduits are on average smaller than aortic
prosthetic conduits. The diameter of the generally cylindrical section typically would
vary according to the natural geometry of the patient. For most patients, the average
diameter of the generally cylindrical section of an aortic prosthetic conduit would range
from about 20 millimeters (mm) to about 40 millimeters, and in further embodiments,
from about 20 mm to about 35 mm. Similarly, the average diameter of the generally
cylindrical section of a pulmonic prosthetic conduit would range from about 8 mm to
about 30 mm, and in further embodiments, from about 12 mm to about 24 mm. While
generally cylindrical section 102 has a generally cylindrical shape, it may be slightly
tapered and/or slightly irregular in shape. However, the diameter of generally cylindrical
section 102 generally varies along its length by no more than about eight percent from the
average diameter, in other embodiments, by no more than about five percent from the
average diameter, and in further embodiments, by no more than about three percent from
the average diameter. A person of ordinary skill in the art will recognize that additional
ranges between these particular ranges are contemplated and are within the present
disclosure.
[0060] In contrast with the generally straight surface along the axial direction of the
generally cylindrical section, the expanded section 104 generally has a curved surface
along the flow direction. The curved surface can have a sinus shape, a partial spherical
shape or other convenient shape. The structure of the valve may influence the shape of
the expanded section. For example, in embodiments in which the native valve is
maintained, scalloped edges of the expanded section attach to the native structure and the
expansion about the attachment edge may naturally form some lobed-type configuration,
although the lobes may have different shapes from natural sinuses. Expanded section 104
generally increases in diameter along curved surface 112 with distance from junction 108
and may reach a maximum diameter such that the diameter then decreases toward inflow
edge 114. In general, the maximum diameter of expanded section 104 is at least about
10% larger than the average diameter of the generally cylindrical section 102, in other
embodiments at least about 12% larger, in further embodiments at least about 15% larger,
and in still other embodiments, about 20% larger than the average diameter of the
generally cylindrical section. A person of ordinary skill in the art will recognize that
additional ranges within the explicit ranges above are contemplated and are within the
present disclosure. Optional reinforcement 106 resists or prevents dilation of the conduit
along generally cylindrical section 102.
[0061] Generally, reinforcements anywhere along the prosthetic conduit, such as
reinforcement 106, is a section of material separate from the prosthetic conduit, although
a reinforcement can be a rolled up section of the material of the prosthetic conduit that is
then attached to the prosthetic conduit to complete the formation of the prosthetic
conduit. Reinforcements generally encircle the circumference of prosthetic conduit,
although the reinforcement can encircle a significant portion of the circumference in
alternative embodiments. Reinforcements can have various shapes consistent with the
location along the circumference of the prosthetic conduit. In particular, the
reinforcement can have various shapes, such as a ring, a band shape, an irregular shape or
other shape that encircles the conduit as desired. Reinforcements can be radio-opaque for
imaging purposes. The thickness of a reinforcement generally depends on the material
used to form the reinforcement. In general, a reinforcement has a thickness from about
0.1 mm to about 3 mm, and in other embodiments, from about 0.2 mm to about 2 mm.
[0062] While embodiments of particular interest have an expanded section,
reinforcements can be useful to prevent dilation of other prosthetic conduits without an
expanded section. In particular, reinforcements can be effective to prevent dilation of a
prosthetic conduit adjacent a valve to maintain proper coaptation of the valve. Prosthetic
conduits adjacent a valve tend to be subjected to dilation due to forces from the valve
function and pressure increases upon valve opening. The valve can be a mechanical valve
or a prosthetic valve with flexible leaflets. Generally, the reinforcement is placed within
about 2 centimeters (cm) from the downstream edge of the prosthetic valve, in other
embodiments within about 1 cm, and in further embodiments, within about 0.5 cm from
the downstream edge of the prosthetic valve. The placement of the reinforcement can be
influenced by the particular type of valve. Larger distances may be appropriate for
embodiments with a mechanical valve or a stented valve, and shorter distances may be
appropriate for embodiments with a stentless valve or for conduits without valves.
[0063] In some embodiments, the inflow edge of the prosthetic conduit is shaped to
facilitate attachment of the conduit to native anatomy. Referring to FIG. 2, prosthetic
conduit 120 has a generally cylindrical section 122, an expanded section 124, and a
reinforcement 126 at junction 128 between generally cylindrical section 122 and
expanded section 124. Inflow edge 130 has an optional sewing ring 132 and/or
reinforcement. While prosthetic conduit 100 of FIG. 1 has an approximately planar
inflow edge 114, prosthetic conduit 120 of FIG. 2 has a shaped inflow edge 130. As
shown in FIG. 2, inflow edge 130 has a scallop shape with three sinuses 134, 136, 138.
The sinuses of this embodiment can be generally analogous to native sinuses. The
scalloped inflow edge is suitable for attachment to a native valve in which the scallops of
the conduit fit between and attach to the scallops and commissures of the native valve
support. During implantation, the coronary arteries can be attached along two of sinuses
134, 136, 138 that are aligned for attachment of the arteries. Holes can be formed in the
sinuses, with a punch, scissors, scalpel or the like, for the attachment of the coronary
arteries. Similarly, sinuses 134, 136, 138 can be positioned between commissures of a
prosthetic valve with flexible leaflets. Attachment of prosthetic conduit 120 along sewing
ring 132 provides a secure attachment while reducing the risk of piercing a leaflet during
implantation. As an alternative to the use of a sewing ring, the edge can be trimmed to
match the native anatomy such that the edge can be directly attached to the native
structure. Other shapes of the inflow edge can be used to facilitate attachment for a
particular situation. For example, a particular shape of the inflow edge can be used with a
separate prosthetic valve component to facilitate implantation and joining of the two
components of the prosthesis.
[0064] In other alternative embodiments, the prosthetic conduit includes tubules for the
attachment of the coronary arteries. Referring to FIGS. 3-5, prosthetic conduit 150
includes a generally tubular section 152, an expanded section 154, a reinforcement 156
and an optional sewing ring 158 and/or inflow edge reinforcement. Tubules 160, 162
extend from expanded section 154 for the attachment of the right and left coronary
arteries. Referring to FIG. 5, tubules 160, 162 provide for fluid flow from the interior 166
of expanded section 154 through the tubules, as noted with the arrows in FIG. 5.
[0065] Prosthetic conduits can be formed from natural materials, synthetic materials or
combinations thereof. Suitable natural materials include, for example, tissue. Appropriate
bioprosthetic tissue materials can be formed from natural tissues, synthetic tissue
matrices and combinations thereof. Synthetic tissue matrices can be formed from
extracellular matrix proteins that are crosslinked to form a tissue matrix or from synthetic
materials, such as polymers, that have or have had viable cells associated with the matrix.
Thus, tissue materials have viable cells or structures formed from cells that are no longer
present. Suitable polymers, such as polyesters, and extracellular matrix proteins, such as
collagen, elastin and combinations thereof, for incorporation into a synthetic tissue matrix
are commercially available. A tissue material can form the entire prosthetic conduit or it
can form one or more portions of the prosthetic conduit.
[0066] Natural, i.e. biological, tissue material for use in the invention includes relatively
intact tissue as well as decellularized tissue. These natural tissues may be obtained from,
for example, native heart valves, portions of native heart valves such as roots, walls and
leaflets, pericardial tissues such as pericardial patches, amniotic sacs, connective tissues,
bypass grafts, tendons, ligaments, skin patches, blood vessels, cartilage, dura mater, skin,
bone, fascia, submucosa, umbilical tissues, and the like. Natural tissues are derived from
a particular animal species, typically mammalian, such as human, bovine, equine, ovine,
porcine, seal or kangaroo. These tissues may include a whole organ, a portion of an organ
or structural tissue components.
[0067] Suitable natural tissues include xenografts, homografts and autografts. These
natural tissues generally include collagen-containing material. Natural tissue is typically,
but not necessarily, soft tissue. Tissue materials are particularly useful for the formation
of tissue heart valve prostheses. The tissue can be decellularized.
[0068] Tissue materials can be fixed by crosslinking. Fixation provides mechanical
stabilization, for example, by preventing enzymatic degradation of the tissue.
Glutaraldehyde, formaldehyde or a combination thereof is typically used for fixation, but
other fixatives can be used, such as epoxides, epoxyamines, diimides and other
difunctional aldehydes. In particular, aldehyde functional groups are highly reactive with
amine groups in proteins, such as collagen. Formaldehyde generally does not function
alone as a satisfactory crosslinking agent. However, formaldehyde is a common sterilant
used to store tissue following glutaraldehyde crosslinking. Epoxyamines are molecules
that generally include both an amine moiety (e.g. a primary, secondary, tertiary, or
quaternary amine) and an epoxide moiety. The epoxyamine compound can be a
monoepoxyamine compound and/or a polyepoxyamine compound. In some
embodiments, the epoxyamine compound is a polyepoxyamine compound having at least
two epoxide moieties and possibly three or more epoxide moieties. In some preferred
embodiments, the polyepoxyamine compound is triglycidylamine (TGA).
[0069] Suitable synthetic materials for incorporation into a prosthetic conduit include
polymers. Polymeric materials can be fabricated from synthetic polymers as well as
purified biological polymers. Appropriate synthetic polymers include, for example,
polyamides (e.g., nylon), polyesters, polystyrenes, polyacrylates, vinyl polymers (e.g.,
polyethylene, polytetrafluoroethylene, polypropylene and polyvinyl chloride),
polycarbonates, polyurethanes, poly dimethylsiloxanes, cellulose acetates, polymethyl
methacrylates, ethylene vinyl acetates, polysulfones, nitrocelluloses and mixtures,
derivative and copolymers thereof. These synthetic polymeric materials can be woven or
knitted into a mesh to form a matrix or substrate. Alternatively, the synthetic polymer
materials can be molded or cast into appropriate forms. Biological polymers can be
naturally occurring or produced in vitro by fermentation and the like or by recombinant
genetic engineering. Suitable biological polymers include, for example, collagen, elastin,
silk, keratin, gelatin, polyamino acids, polysaccharides (e.g., cellulose and starch) and
copolymers thereof Polymer materials can be impregnated with structural proteins, such
as collagen, to impart desired levels of resistance to leaking.
[0070] The reinforcements can be formed from natural materials, synthetic materials or a
combination thereof. The reinforcement preferably is somewhat flexible, although the
reinforcement generally is formed from a durable and non-extensible material. In general,
the reinforcement can be formed from one or more layers of tissue, such as pericardium,
that is placed around the prosthetic conduit and sutured, stapled, glued or otherwise
fastened around the conduit. The reinforcement can be similarly formed from one or
more layers of fabric or other polymer sheeting. Similarly, the reinforcement can be
formed from a roll of tissue or synthetic material. Also, the reinforcement can be formed
from bands of metal or other inorganic material.
[0071] Sewing rings can be formed also from tissue materials and/or synthetic polymer
materials. In addition to the synthetic polymers described above, sewing rings can be
formed from bioresorbable polymers. Suitable bioresorbable polymers include, for
example, dextran, hydroxyethyl starch, derivatives of gelatin, polyvinylpyrrolidone,
polyvinyl alcohol, poly[N-(2-hydroxypropyl) methacrylamide], poly(hydroxy acids),
poly(epsilon-caprolactone), polylactic acid, polyglycolic acid, poly(dimethyl glycolic
acid), poly(hydroxy butyrate), and similar copolymers.
[0072] Prosthetic Heart Valves
[0073] The aortic heart valve or the pulmonary heart valve can be replaced along with the
portion of the aorta or pulmonary artery. The valve can be secured to native structure
during implantation, or the prosthetic valve can be combined with a portion of the
prosthetic conduit. Specifically, mechanical valves can be secured to the native valve root
or to a prosthetic conduit. A valve with flexible leaflets can be secured to both the native
valve root and a portion of the native artery extending from the native valve root or,
alternatively, to a portion of the prosthetic conduit that is then fastened to the native valve
root. If the valve is secured to native structure, the implantation of the prosthetic valve
can be performed in the same surgical procedure as the replacement of an adjacent
section of aorta or pulmonary artery with the prosthetic conduit.
[0074] A representative mechanical heart valve is shown in FIG. 6. A bileaflet
mechanical heart valve prosthesis 200 includes an orifice ring 202, which retains two
occluders 204, 206. Occluders 204, 206 rotate at pivots 212, 214 and two additional
opposed pivots (not shown) symmetrically positioned on the inner luminal surface 216 of
orifice ring 202. Inner luminal surface 216 of orifice ring 202 forms a flow path through
the valve that can be opened or closed by the pivoting of occluders 204, 206. Blood flows
through valve 200 in an effectively unidirectional way. A sewing ring 218 is placed
around orifice ring 202 to facilitate attachment with the patient's tissue during
implantation of the valve. Other mechanical valves, including, for example, valves with a
single leaflet or more than two leaflets or a ball and cage design, can be used in place of
the particular embodiment in FIG. 6 as replacement for the native aortic valve or
pulmonary valve.
[0075] An embodiment of a stentless tissue-based heart valve prosthesis is shown in FIG.
7. Heart valve prosthesis 250 includes a harvested tissue heart valve 252, such as a
porcine valve. For implantation of a porcine valve into a human, harvested tissue valve
252 generally is crosslinked to reduce the immune response. Prosthesis 250 can further
include a fabric cover 254. Valve 252 has three leaflets 256, 258, 260 that meet at
coaptation surfaces 262. Valve 252 has a generally annular base 264 and three
commissure supports 266, 268, 270 at which the free edge of the leaflets attach. Three
scallops 272 extend between commissure supports 266, 268, 270 along the upper edge of
the prosthesis. Lower edge 274 of prosthesis 250 is the inflow end, and upper edge 276 is
the outflow end. In this embodiment, lower edge 274 is generally planar, in contrast with
the scalloped upper edge 276 of the prosthesis. The prosthesis shown in FIG. 7 is suitable
for implantation at the aortic or pulmonary positions in a heart.
[0076] Alternative embodiments of heart valve prostheses with flexible leaflets involve
assembly of leaflets in a desired shape from a tissue or polymer material. One or more
leaflets are assembled in association with a support structure to form either a stented or
stentless valve, depending on the nature of the support structure. The support structure
can be formed from natural materials, synthetic materials or a combination thereof.
[0077] A representative embodiment of a stented valve with flexible leaflets is shown in
FIG. 8. Heart valve prosthesis 300 includes leaflets 302, 304, 306 and stent 308. Stent
308 includes commissure supports 310, 312, 314 and scallops 316, 318, 320 between the
commissure supports. Free edges 322, 324, 326 of leaflets 302, 304, 306, respectively,
join stent 308 at the commissure supports 310, 312, 314. Attached edges 328, 330, 332 of
leaflets 302, 304, 306 also attach to stent 308 along scallops 316, 318, 320. Base 334 of
stent/support structure 308 generally is a cylindrical ring that forms the opening into the
valve at the upstream or inflow end of the valve. Other stented and stentless polymer and
tissue based valves can similarly be used and may have fewer or more leaflets than the
three leaflet valve shown in FIG. 8. The design of polymer leaflets for prosthetic heart
valves is described further in copending and commonly assigned U.S. patent application
Ser. No. 09/955,703 to Cai et al., entitled "POLYMER LEAFLET DESIGNS FOR
MEDICAL DEVICES," incorporated herein by reference.
[0078] Prostheses With Conduits and Valves
[0079] The prostheses can include both a prosthetic conduit and a prosthetic valve. These
prostheses can be a single integral unit with the valve integrated into a section of
prosthetic conduit. Alternatively, the prostheses can include two or more sections of
prosthetic conduit that fit together to form an entire conduit section with one section
including the prosthetic valve. Whether or not a prosthesis has one or more sections of
prosthetic conduit, a conduit for aortic replacement generally includes appropriate
structure for the connection of the coronary arteries. Also, if the valve has a profile
extending sufficiently into the artery, the valve should be mounted such that the valve
commissure supports do not interfere with flow into the coronary arteries.
[0080] A first embodiment of a prosthesis with a single prosthetic conduit portion and a
prosthetic heart valve is shown in a cut-away view in FIG. 9. Prosthesis 350 includes
prosthetic conduit 352 and mechanical heart valve 354. Prosthetic conduit 352 includes a
generally cylindrical section 356, an expanded section 358 and optional reinforcement
360. This embodiment can be used for replacement of the pulmonary heart valve and a
corresponding section of the pulmonary artery if the valve is placed is placed away from
the inflow edge 368, as shown in phantom lines in FIG. 9. Also, the aortic valve and
corresponding section of the aorta can be replaced with prosthesis 350 if the valve has a
sufficiently low profile such that the coronary arteries can be connected to holes in the
side of the conduit without interference from the valve leaflets. If it is desirable to orient
the valve, markings 362 can be placed on the exterior of the prosthesis to correspond to
the commissures of the valve. In alternative embodiments for the aorta, tubules can
provide fluid communication between the interior of expanded section 358 and the
exterior of conduit 352 for the attachment of coronary arteries.
[0081] Mechanical valve 354 and an optional sewing ring 366 are connected together
with conduit 352 at the inflow edge 368 of conduit 352. In the embodiment of FIG. 9,
mechanical valve 354 includes an orifice ring 376 and two leaflets 378, 380 that pivot to
open and close the lumen within orifice ring 376. If prosthetic valve 354 has a profile that
does not approach the locations for connecting the coronary arteries, the coronary arteries
can be attached to the prosthesis without particular attention to the orientation of the
valve.
[0082] The dimensions of prosthetic conduit 352 are generally similar to the dimensions
of the prosthetic conduits in FIGS. 1-3 except that the expanded section covers the valve.
In valved embodiments, the expanded 358 section generally reaches a maximum diameter
along the axial, i.e., flow, direction and has a smaller diameter relative to the maximum at
both the connection with the valve and the connection with the generally cylindrical
section 356. The maximum diameter is generally equivalent to the maximum diameters
for the embodiments in FIGS. 1-3. The diameter at the inflow edge is generally no more
than about 10% greater than the average diameter of the generally cylindrical section and
may be approximately equal to the average diameter of the generally cylindrical section.
Suitable materials for formation of the prosthetic conduit are described above.
[0083] An alternative embodiment of a valved prosthesis is shown in a cut-away view in
FIG. 10. Prosthesis 400 includes a prosthetic conduit 402 and a prosthetic valve 404
having flexible leaflets. Prosthetic conduit 402 includes a generally cylindrical section
406, an expanded section 408 and a reinforcement 410. Optional tubules 412, 414
provide fluid communication between the interior of conduit 402 and the exterior of
conduit 402 for the attachment of coronary arteries. Prosthetic valve 404 and optional
sewing ring 416 and/or reinforcement are connected together with conduit 402 at the
inflow edge 418 of conduit 402. In the embodiment of FIG. 10, prosthetic valve 404
includes a support structure 430 with commissure supports 432 (with one shown in FIG.
10) and flexible leaflets 434, 436. Prosthetic valve 404 can be stented or stentless. The
inflow edge generally can be planar or scalloped. Prosthetic valve 404 can include one,
two, three or more flexible leaflets and a corresponding number of commissure supports
to support the leaflets.
[0084] Commissure supports 432 are oriented such that the commissure supports do not
block the flow into tubules 412, 414. Thus, by taking into account the orientation of valve
404 relative to the tubules during the manufacture of prosthesis 400, the surgeon does not
need to worry about the orientation of valve 404 during implantation other than orienting
the tubules for attachment of the coronary arteries. By attaching the coronary arteries at
tubules 412, 414, proper function of the prosthesis is obtained without any inappropriate
blockage due to the valve commissures. Valve 404 can be stented or stentless. If valve
404 is stentless, support structure 430 is attached to the inner walls of expanded section
408 to maintain valve function against fluid pressures. For embodiments with stentless
valves, the support structure generally cannot be expanded significantly without effecting
proper coaptation of the leaflets, although the support structure may flare out slightly.
Thus, the expanded section forms lobes between the commissures and scallops of the
support structure. While the inflow edge is shown as planar, the inflow edge can include
a slight scalloped shape to facilitate attachment to the native annulus following removal
of the native leaflets.
[0085] Embodiments similar to the prosthesis in FIG. 10 without tubules can be used for
replacement of the pulmonary heart valve and adjacent section of the pulmonary artery.
Similarly, the aortic heart valve and adjacent section of aorta can be replaced with an
embodiment similar to the prosthesis in FIG. 10 without tubules 412, 414 if attachment of
the coronary arteries can be performed without interference from the commissure
supports. In particular, embodiments without tubules can be used for aortic implantation
if appropriate markings are placed on the outside of the prosthesis to direct the surgeon
how to orient the valve and/or to indicate appropriate locations for the attachment of the
coronary arteries. For example, the outline of the commissure supports can be marked on
the outside of section 408 such that holes can be made away from the commissure
supports for attachment of the coronary arteries. The markings of the commissure
supports can be similarly used to orient the prosthesis for implantation. In additional
embodiments, expanded section 408 and/or reinforcement 410 can be omitted. For
example, tubules 412, 414 can be attached directly to generally cylindrical section 406
that connects to the prosthetic valve. While such embodiments would not have the
advantages provided by the expanded section, the presence of the tubules can provide
advantages for the attachment of the coronary arteries. Similar variations are possible for
the embodiment shown in FIG. 9.
[0086] Additional embodiments of the prosthesis include two or more sections of conduit
that are connected to complete the prosthesis. While these sections can be implanted in
any order, generally the valved section is implanted first, then the non-valved section(s)
is (are) attached to the valved section, and the artery is attached to the implanted
prosthesis. A first embodiment of a prosthesis with multiple sections of prosthetic conduit
is shown in a cut-away view in FIG. 11. Prosthesis 450 includes a first section 452 and
second section 454. First section 452 includes a generally cylindrical portion 456, a
reinforcement 458, an expanded attachment section 460 and an optional sewing ring 462.
Expanded attachment section 460 attaches to second section 454. The size of expanded
attachment section 460 can be selected to facilitate connection of first section 452 and
second section 454 as long as expanded attachment section 460 does not interfere with
attachment of the coronary arteries.
[0087] Second section 454 includes an expanded prosthetic conduit 470 and a prosthetic
valve 472. Expanded prosthetic conduit 470 generally has curved walls and has a larger
average diameter than generally cylindrical portion 456. Expanded prosthetic conduit 470
corresponds with the expanded sections of the prostheses in FIGS. 1-3, 9 and 10. As
shown in FIG. 11, prosthetic valve 472 has flexible leaflets, although a mechanical valve
can be substituted for the valve with flexible leaflets. Second section 454 further includes
tubules 474, 476 for connection of the coronary arteries. Since the orientation of the valve
is sufficiently visible when first section 452 is not attached, the prosthetic conduit is
designed without tubules in alternative embodiments while still providing for the
attachment of the coronary arteries. Thus, the second section 454 can be oriented visibly
by the surgeon during implantation to allow for attachment of the coronary arteries at a
hole in the prosthesis without resulting in blockage of flow into the arteries by the valve
structure. Second section 454 also has an optional sewing ring 478 and/or reinforcement
at the inflow edge 480 and an optional sewing ring 482 and/or reinforcement at the
outflow edge 484.
[0088] Some improved embodiments for replacement of the aorta can include
reinforcements even without an expanded section. Referring to FIG. 12, prosthesis 500
includes a generally cylindrical prosthetic conduit 502 having an inflow edge 504 and an
outflow edge 506, a valve 508, shown schematically in phantom lines within prosthetic
conduit 502. Prosthetic conduit 502 can have one or more reinforcements. As shown in
FIG. 12, prosthetic conduit 502 comprises a reinforcement 510 near the outflow edge of
valve 508, reinforcement 512 near the outflow edge and reinforcement 514 near the
inflow edge. Reinforcements 510, 512 and 514 reduce or eliminate dilation of the conduit
due to fluid pressures.
[0089] In embodiments for the replacement of the pulmonary artery, it may be
particularly desirable to have a reinforcement at or near the outflow edge to prevent
collapse of the prosthetic conduit due to pressure drops. Pressure at the outflow edge can
reach values, for example, that are 1/5 of the pressure at the inflow edge. Referring to
FIG. 13, prosthesis 516 has a prosthetic conduit 518 having an inflow edge 520 and an
outflow edge 522, an optional valve 524, shown schematically in phantom lines within
prosthetic conduit 518. In relevant embodiments, inflow edge 520 is generally about one
centimeter to about 5 centimeters from valve 524. Prosthetic conduit 518 can have one or
more reinforcements. As shown in FIG. 13, prosthetic conduit includes an outflow edge
reinforcement 526, a reinforcement 528 near the inflow edge of valve 524 and
reinforcement 530 near inflow edge 520. Generally, outflow edge reinforcement 526 is
placed at the edge or within about one centimeter of the outflow of the valve. Outflow
edge reinforcement 526 is generally stiff and is attached to prosthetic conduit 518 to
resist collapse of the conduit. Outflow reinforcement 526 can have similar dimensions
and can be formed from similar materials as other reinforcements. Reinforcement 530
may be oblong or oval shape and is generally stiff, although the reinforcement can be
bendable to allow for adjustment in anatomy. Correspondingly, inflow edge 520 can be at
an angle relative to the central axis of prosthetic conduit 518 to facilitate attachment to
the heart.
[0090] Construction of the Prosthetic Conduits
[0091] The various embodiments of the prostheses can be assembled from appropriate
sections of material. Using either natural or synthetic materials, prosthetic conduits can
be formed directly from conduit shaped components. However, in other embodiments,
prosthetic conduits are formed at least partially from sheet material with appropriate
processing to form the curved portions of the prosthetic conduit. While the details of the
assembly process will depend on the specific features of the prosthesis, these details can
be adapted from the general description that follows.
[0092] With respect to tissue materials, a xenograft aorta with the natural sinuses or
pulmonary artery with the natural sinuses can be used for the prosthetic conduit following
fixing, trimming, cutting to the desired dimensions, and other treatment. The natural
conduits can be opened up for the attachment of a prosthetic valve, if desired, and
reassembled to reestablish the conduit form using suture, staples, biocompatible adhesive,
other like fasteners or combinations thereof. Suitable biocompatible adhesives are
commercially available, for example, as surgical adhesives. Other natural conduits, such
as intestine, bronchus or other large artery or vein, also can be adapted for use in the
present prostheses. With respect to synthetic materials, polymers and the like can be
extruded, molded, woven or cast into a shape, including the curves of the sinuses. As
with natural tissue conduits, the formed synthetic materials can be opened up for the
attachment of a prosthetic valve and reassembled to form the conduit. However, in other
embodiments, a wide range of materials can be used if the materials are conformed into
the desired shape, generally from planar sheet material.
[0093] For a tissue-based prosthetic conduit without a valve, several illustrative
approaches can be used for forming the prosthesis from initially planar, i.e., sheet,
material. For example, the prosthetic conduit can be formed from a sheet of material,
either tissue, such as pericardium, polymer, such as fabric, or other appropriate
biocompatible material, that is shaped to accommodate the different diameters at the
different portions of the prosthetic conduit. A representative sheet of material cut in a
suitable form is shown in FIG. 14. Specifically, sheet 540 has a rectangular portion 542
and an expanded section 544. Rectangular portion 542 can be folded around a cylindrical
shaft to bring the opposite edges together. The opposite edges can be stitched, glued or
otherwised fastened to form a generally cylindrical section of the resulting prosthetic
conduit. In addition, the opposite edges of the expanded section 544 can be fastened
together to form the extended section of the resulting prosthetic conduit. While the
resulting structure formed from connecting the attached edges of expanded section 544
may not have a balloon shape, it would have roughly the variation in diameter desired.
Also, it can be placed over a spherical or other comparable shape to help the material
conform more closely to a desired shape. A person of ordinary skill in the art will
recognize that various shapes can function appropriately depending on the overall
structure of the prosthetic conduit.
[0094] Similarly, a rectangular or curved shape of planar tissue or other material can be
placed over a mandrel having a desired shape to conform the material to the shape due to
tension on the material against the mandrel. Tissue and some polymers will gradually
distort to the shape of the mandrel if it is secured to the mandrel with the application of
tension. An appropriate mandrel is shown in FIG. 15. Mandrel 550 includes a handle 552,
a generally cylindrical section 554 and a curved section 556. Handle 552 provides for
holding, supporting and moving the mandrel and can have convenient shape and size
consistent with its function. For two component prostheses, generally two mandrels, one
for each component, is used to shape the components.
[0095] Generally cylindrical section 554 provides for the formation of a generally
cylindrical section of the prosthetic conduit, and curved section 556 provides for the
formation of the expanded section of the prosthetic conduit. Generally cylindrical section
554 and curved section 556 have appropriate sizes and shapes to form the corresponding
sections. The top of curved section 556 generally can have any convenient shape since
the material typically does not extend over the top of curved section 556. The tissue or
other material is fastened temporarily to mandrel 550 since the material must be removed
from the mandrel for use. For example, suction, a non-permanent biocompatible adhesive
or suture can be used for the temporary mounting onto the mandrel. After removing the
contoured material from the mandrel, a permanent seam can be put in place with suture,
permanent adhesive or other fastener.
[0096] With the use of a mandrel, the initial shape of the tissue or other material is
somewhat less important since, to achieve the desired shape, the material can distort to
conform to the mandrel. Overlap of material in the contoured configuration generally
would not detract from the properties of the prosthesis. Thus, a material section with
rectangular sections can be used, as shown in FIG. 16. Material section 560 has a first
rectangular section 562, for forming the generally cylindrical section of the conduit, and a
second rectangular section 564, for forming the expanded section of the conduit. Second
rectangular section 564 is conformed to the shape of a mandrel to introduce desired
curvature. More elaborate planar cuts can be performed. For example, the three
dimensional shape that is desired can be formed as a planar projection that assembles
directly into the approximate three dimensional shape. These cut sections can involve cut
out sections such that the folds more closely assemble into the desired three dimensional
surface similar to planar map projections of a globe. The object can be folded into the
correct shape or placed on a mandrel with the seams sutured, glued or otherwise fastened
to form the desired shape.
[0097] The cutting of the tissue or other material to the appropriate shape can be
performed by hand by a skilled technician. The material can be cut along a die or with a
die with sharp edges. Alternatively, focused beam cutting can be used to introduce more
automated features to the process. Focused beam cutting of tissue and other materials for
the formation of prostheses is described, for example, in copending and commonly
assigned U.S. patent application Ser. No. 09/755,424 to Guzik, entitled "Focused Beam
Cutting Of Materials," incorporated herein by reference.
[0098] To form the two-piece prosthetic conduit embodiments, such as the embodiment
in FIG. 11, corresponding portions of material can be used to form each piece. For
example, referring to FIG. 17, segments 570, 572 can be configured to form two elements
of a prosthetic conduit that fit together to form a complete prosthetic conduit. Element
570 can be wrapped around a cylindrical member to form a generally cylindrical
prosthetic conduit element with a portion for connecting to an expanded section. Element
572 can be wrapped to form an expanded section of a prosthetic conduit. In some
embodiments, the expanded section becomes a valved portion of the prosthetic conduit.
Element 572 can be wrapped around a spherical mandrel or other convenient shape that
provides for joining the opposite edges to form a reasonably shaped expanded section. A
one-piece prosthesis can be formed in two or more pieces that are connected to form the
prosthesis. In these embodiments, each piece can be separately shaped.
[0099] A prosthetic heart valve can be fastened to the appropriate prosthetic conduit
before, during or after formation of the prosthetic conduit into the appropriate shape. In
particular, mechanical valves, due to their relatively low profile, can be fastened to the
prosthetic conduit after forming the conduit. The mechanical valve can be connected at
the inflow edge of the prosthetic conduit with an attachment around the base of the valve,
such as a single suture line, an adhesive bond, staples or the like. A stented prosthetic
valve with flexible leaflets can be attached similarly to a mechanical valve since only the
inflow edge is attached. The stent maintains leaflet function against fluid pressures
without any further attachment of the commissure supports.
[0100] A stentless prosthetic valve with flexible leaflets generally requires attachment of
the commissure supports to the prosthetic conduit. Thus, a stentless prosthetic valve with
flexible leaflets requires fastening at the inflow edge and the outflow edge. The outflow
edge can be somewhat difficult to fasten within a prosthetic conduit, such as the conduits
in FIGS. 1-3. Alternatively, the inflow edge can be fastened within an expanded
prosthetic conduit component, such as second section 454 of FIG. 11. The outflow edge
of the expanded section of the two component conduit prosthesis provides some access to
the outflow edge of the valve within the conduit.
[0101] In other embodiments, the inflow edge of the valve can be fastened to the conduit
material as the prosthetic conduit portion is curved into the desired shape such that the
contouring of the conduit and the fastening of the inflow edge, and possibly outflow
edge, is performed as part of the operation of forming the conduit. The conduit material
can cover the valve to introduce some shape along the inflow edge of the conduit, such as
a slight scallop shape, to facilitate implantation along the natural annulus. In still other
embodiments, individual leaflets can be fastened to the material forming the prosthetic
conduit before the material is shaped and fastened into the conduit configuration. For
example, a leaflet section 580 includes an individual leaflet 582 along with a portion of
the aortic wall 584, as a support structure, as shown in FIG. 18. Leaflet sections 580, for
example, can be harvested from a porcine valve or formed from pericardium. The leaflet
component can be cut from a sheet of pericardium and shaped to have the scallop shape
of the attached edge and the proper dimensions of the free edge to have desired
coaptation when assembled with the other leaflets. Three leaflet sections 580 can be
attached individually to the prosthetic conduit material, or the leaflets can first be
fastened together to form a three leaflet section 586, as shown in FIG. 19. Referring to
FIG. 20, three leaflet section 586 is attached to sheet 540 to form a valved-conduit form
588 that is contoured into a valved-conduit prosthesis.
[0102] In addition, the conduit and the leaflets can be cut from sheets of biocompatible
material, such as pericardium. In one embodiment, the leaflets are cut as a part of the
conduit and the leaflet portions are folded into place and fastened. Referring to FIG. 21,
cut tissue portion 600 includes a prosthetic conduit section 602 and three leaflet sections
604, 606, 608. Leaflet sections 604, 606, 608 are folded, as shown with the arrow, and
fastened to position the leaflets along the prosthetic conduit. The conduit section is then
contoured and fastened to form the prosthetic conduit with the leaflets appropriately
positioned for valve function. Similarly, the leaflet sections can be cut from the same or a
separate sheet of pericardium, or other biocompatible material, and fastened to the
appropriate location on the section of biocompatible material to be formed into the
prosthetic conduit. Referring to FIG. 22, leaflet sections 610, 612, 614 are fastened to
prosthetic conduit section 616. The conduit section is contoured and fastened to form the
prosthetic conduit.
[0103] Implantation of the Prostheses
[0104] The procedure for implanting the prosthetic conduit varies depending on the
particular embodiment of the prosthesis and whether or not the corresponding heart valve
is also replaced. Generally, with any of the prostheses, the patient is placed on
cardiopulmonary bypass, and the patient's chest cavity is opened to provide access to the
appropriate artery at the connection with the heart. An appropriate section of the artery is
removed for replacement/reconstruction.
[0105] If the heart valve is not replaced, the artery is cut near the heart along the sinuses
of Valsalva with care not to damage the leaflets of the heart valve. The artery is also cut
downstream from the sinuses such that the portion of the artery can be removed and
replaced. Generally, the artery can be cut along the commissures and scallops of the
valve. While the artery is severed, the heart valve can be accessed for examination and/or
any repair. The removed section of artery can be replaced with an embodiment of the
improved prosthetic conduits described herein. In particular, for appropriate
embodiments, an expanded section of the prosthetic conduit is attached along the cut
sinuses. The generally cylindrical section of the prosthetic conduit is attached to the other
free end of the artery. Suture or alternatives to suture, such as staples, barbed pins,
surgical adhesives and the like, can be used to secure the prosthetic conduit to remaining
portions of the native artery.
[0106] For the aorta, the coronary arteries may or may not be disconnected when the
aorta is cut along the sinuses. Generally, the coronary arteries are cut along the surface of
the aorta and reattached to the expanded section of the prosthetic conduit. For example,
the coronary arteries can be inserted into a hole in the prosthetic conduit and sutured in
place, or can be attached to a tubule and sutured in place. Again, suture or alternatives to
suture can be used to secure the coronary arteries to the prosthetic conduit. The presence
of the expanded section of the prosthetic conduit facilitates the reattachment of the
coronary arteries since the expanded section of the prosthetic conduit is similar to the
native structure such that significant repositioning of the coronary arteries should not be
necessary to reach the prosthesis for attachment.
[0107] As noted above, the heart valve is accessible when the portion of the aorta or
pulmonary artery is removed for reconstruction. While the valve is accessible, the valve
can be replaced without replacing the corresponding section of the artery adjacent the
heart. In particular, with the valve accessible through the open end of the artery, the
leaflets of the native valve can be removed with a scissors or the like. With the valve
removed, a mechanical heart valve can be attached at the native valve root. Similarly, a
stented or stentless valve with tissue or polymer flexible leaflets can be implanted. A
stented valve can be implanted by attachment at the native root similar to a mechanical
prosthetic heart valve. A stentless valve with flexible leaflets is generally attached at both
edges of the valve. The inflow edge is secured at the native root while the outflow edge
of the valve is secured to the artery wall through the opening of the artery.
[0108] Alternatively, the heart valve can be replaced along with the corresponding
section of artery. A one piece or a multiple-piece prosthetic conduit can be used with the
heart valve attached to an appropriate portion of the prosthetic conduit. Since the
prosthetic valve is attached to the prosthetic conduit, the heart valve is not separately
implanted with these embodiments. Thus, the implantation of the prosthetic conduit also
results in the replacement of the heart valve. The prosthesis can be fastened to the heart
with suture, staples, barbed pins, surgical adhesives and the like. In contrast with some of
the other embodiments, the native artery is detached at the location of the valve. With this
approach, the sinuses of the native structure are removed and replaced with the prosthetic
conduit. For the aorta, the coronary arteries can be reattached at a hole in the prosthetic
conduit, or can be attached at a tubule extending from the prosthetic conduit. As with the
other embodiments, the presence of an expanded section facilitates attachment of the
coronary arteries. Facilitating the replacement of the heart valve and/or reattachment of
the coronary arteries can shorten the surgical time and correspondingly reduce the time
during which the patient is subjected to cardiopulmonary bypass. Decreasing the amount
of time on a cardiopulmonary bypass can reduce risk to the patient.
[0109] Storing and Distribution
[0110] The prosthetic conduits with or without prosthetic valves can be stored following
their formation. The appropriate storage technique depends on the nature of the materials
incorporated in the prosthesis. Preferred storage techniques minimize the risk of
microbial contamination. Prostheses with tissue components can be stored under
conditions that keep the tissue from drying out. For example, prostheses with tissue
components can be stored in a sealed container with sterile buffer, saline solution and/or
an antimicrobial agent, such as formaldehyde, glutaraldehyde or alcohol. Prostheses
without any tissue components generally can be stored in dry, sealed containers. The
containers can be sterilized prior to sealing, for example, with steam, ethylene oxide, beta
propriolactone, chlorine dioxide, gamma radiation, ozone or combinations thereof, or
following sealing, using, for example, heat, steam, ethylene oxide or radiation, such as
microwaves, gamma radiation or electron beam radiation.
[0111] The prostheses generally are packaged in sealed and sterile containers for
shipping. To ensure maintenance of acceptable levels of sterility, prostheses, including
tissue, can be transferred to the sterile container using accepted aseptic protocols. The
containers can be dated such that the date reflects the maximum advisable storage time.
[0112] The containers generally are packaged with instructions for the use of the medical
devices along with desired and/or required labels. The containers with the prosthetic
conduits are distributed to health care professionals for use in appropriate medical
procedures, such as implantation of the prosthesis and the like. The implantation is
performed by a qualified health care professional.
[0113] The embodiments described above are intended to be illustrative and not limiting.
Additional embodiments are within the claims below. Although the present invention has
been described with reference to particular embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without departing from the spirit
and scope of the invention.
*****
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PubMed Central
Copyright © 2000, Texas Heart® Institute, Houston
Tex Heart Inst J. 2000; 27 (4): 369–385
Abstract
Update on Endovascular Treatment of Peripheral Vascular Disease: New
Tools, Techniques, and Indications
Zvonimir Krajcer, MD and Marcus H. Howell, MD
Full Text
Figures/Tables
The Department of Cardiology, Texas Heart Institute at St. Luke's Episcop
Hospital, Houston, Texas 77030
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Contents
Address for reprints: Zvonimir Krajcer, MD, Suite 2780, 6624 Fannin
Street, Houston, TX 77030
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Top
Abstract
Introduction
Percutaneous Transluminal
Abstract
The treatment of peripheral vascular disease is one of the most rapidly
expanding fields of medicine today. At one time, patients who had periphe
Balloon Angioplasty
Carotid Angioplasty
Endoluminal Treatment of
Abdominal ...
Thrombolytic Therapy for
Arterial ...
Vascular Radiation
Therapy
Percutaneous Hemostatic
Puncture Closure ...
Gene Therapy
Covered Stents
Old Devices, New Uses
References
vascular disease had few medical or surgical options. Now, however, optio
abound. The number of peripheral interventions increased from 90,000 in
1994 to more than 200,000 in 1997, and endovascular techniques may soo
replace up to 50% of traditional vascular operations.
Cardiologists, interventional radiologists, and vascular surgeons bring
various types of expertise to endovascular intervention; nonetheless, they
seem to share similar levels of enthusiasm about this treatment option. The
many advantages to the patient that such intervention offers over tradition
surgery, such as the avoidance of anesthesia and other surgical risks, the
rapid recovery time, and the relatively low treatment costs, provide
encouragement to these specialists.
Endovascular intervention requires dedication on the part of practitioners,
because it demands such complete knowledge of vascular disease and of t
anatomic changes experienced by the patient. The challenge is intensified
the continual introduction of new products and methods. We hope, herein,
offer pertinent information about recent advances in interventional
techniques and devices, and to provide a framework for future education.
Keywords: Angioplasty, transluminal percutaneous, aortic aneurysm,
abdominal, arterial occlusive diseases, blood vessel prosthesis, carotid
stenosis, catheterization/methods, collagen/therapeutic use, embolism,
peripheral vascular diseases/radiotherapy, gene transfer, hemostatic
techniques, prosthesis design, thrombosis/drug therapy/radiotherapy
Top
Abstract
Introduction
Percutaneous Transluminal
Balloon Angioplasty
Carotid Angioplasty
Endoluminal Treatment of
Abdominal ...
Thrombolytic Therapy for
Arterial ...
Vascular Radiation
Therapy
Percutaneous Hemostatic
Puncture Closure ...
Gene Therapy
Covered Stents
Old Devices, New Uses
References
Introduction
Endovascular intervention is the fastest growing area of vascular medicine
Peripheral vascular interventions have been developed with these aims: to
avoid the risk of general or epidural anesthesia and the risk of conventiona
surgical procedures, to reduce the patient's discomfort and recovery time,
to lower the cost of treatment.
Endovascular intervention has generated great enthusiasm among speciali
in cardiology, interventional radiology, and vascular surgery. The number
radiologic and angiographic heart procedures has doubled since 1994. 1
Approximately 2.5 million radiologic diagnostic procedures and 3.2 millio
angiographic heart procedures are performed annually in the United States
Since 1994, the number of peripheral interventional procedures has increa
from 90,000 to more than 200,000 in 1997 2 —this far exceeds the increas
in coronary interventional procedures.
Cardiovascular interventional techniques require specialized skills and
training in diagnostic angiography and interventional techniques. To gain
expertise in peripheral interventions, knowledge must also be acquired wit
regard to the natural history of peripheral vascular disease and the anatom
changes that occur in patients who have this disease. Familiarity with vari
therapeutic alternatives is necessary, as well. 3
Since the original description of percutaneous balloon angioplasty more th
25 years ago by Andreas Gruentzig, 4 endovascular interventionists have
been able to treat patients with coronary and peripheral arterial disease usi
a variety of interventional techniques. Such treatment has undergone
dramatic expansion during the last few decades (Table I).
Top
Abstract
Introduction
Percutaneous Transluminal
Balloon Angioplasty
Carotid Angioplasty
Endoluminal Treatment of
Abdominal ...
Thrombolytic Therapy for
Arterial ...
Vascular Radiation
Therapy
Percutaneous Hemostatic
Puncture Closure ...
Gene Therapy
Covered Stents
Old Devices, New Uses
References
Top
Abstract
Introduction
Percutaneous Transluminal
Balloon Angioplasty
Carotid Angioplasty
Endoluminal Treatment of
Abdominal ...
Thrombolytic Therapy for
Arterial ...
Vascular Radiation
Therapy
Percutaneous Hemostatic
Puncture Closure ...
Gene Therapy
Covered Stents
Old Devices, New Uses
References
Percutaneous Transluminal Balloon Angioplasty
Percutaneous transluminal balloon angioplasty (PTA) has been used
successfully for treating coronary, renal, iliac, femoral, tibio-peroneal,
subclavian, carotid, and other arterial stenoses. The best results of PTA are
achieved in stenotic lesions that are short, concentric, and noncalcific.
Despite substantial improvements in balloon and catheter technology,
PTAstill produces unacceptable restenosis rates in complex lesions and of
requires reintervention. This is particularly common when the complex
lesions are in the carotid, renal, femoropopliteal, and tibio-peroneal arterie
Several mechanisms can contribute to this recurrence, including elastic
recoil, vascular remodeling, and intimal hyperplasia.
Through the technical innovation of stents, the problems of elastic recoil a
vascular remodeling have for the most part been solved, and a large
percentage of vessels remain free of restenosis. However, intimal
hyperplasia, including smooth-muscle-cell proliferation, requires further
research to find a solution.
Carotid Angioplasty
For many years, PTA was considered unsuitable as a treatment for
atherosclerotic carotid stenosis, because atherosclerotic plaque is not
removed by this method. Although PTA was 1st performed by Kerber's
group in 1980, 6 the procedure is still considered controversial for
extracranial carotid artery stenosis. The European trial CAVATAS, 7 whic
compared carotid endarterectomy to PTA of the extracranial carotid artery
a prospective randomized study, showed no essential difference between t
results of the 2 methods over a period of more than 4 years.
Interventionists have been reluctant to use this technique due to the risk of
dislodging atherosclerotic débris, causing cerebral embolism and stroke.
Simple balloon angioplasty can lead to embolism and suboptimal long-ter
results for various reasons, including heterogeneous composition of
atherosclerotic plaque at the carotid bifurcation, residual stenosis after PTA
(frequently present), and intimal disruption and dissection leading to
thrombus formation.
Stent-Supported Carotid Angioplasty
Technologic advances in the endovascular treatment of peripheral vascula
disease, along with the introduction of stents, have been the impetus for
various investigational trials concerned with treating extracranial carotid
artery occlusive disease. The technique of stent-supported carotid
angioplasty (SSCA) has expanded the indications and reduced the risk of
neurologic complications that frequently occur with PTA for extracranial
carotid artery stenosis. Stent-supported carotid angioplasty, however, is no
an approved procedure in the United States. At this time, the consensus
among experienced interventionists is that carotid angioplasty should not b
performed without the use of a stent (even though no stent has been appro
for this purpose). The preliminary results of SSCA 8–11 are encouraging;
however, no randomized trial comparing PTA and stenting to carotid
endarterectomy has been completed to validate this procedure. The
preliminary results of SSCA that are currently available 8–11 are based on
single-center, non-randomized trials that have used different study designs
and techniques.
Roubin and colleagues 8 reported on a series of 238 SSCA procedures in
which a 6.3% incidence of neurologic complications was observed.
Diethrich's group, 9 in a series of 110 patients treated with stent placement
(117 carotid arteries), reported 7 cerebrovascular accidents (6.4%) and 5
transient ischemic attacks (4.5%). In 1997, Wholey and co-authors 10
described 114 procedures, with successful Palmaz stent placement in 108
carotid arteries. Complications included 4 cerebrovascular accidents (2 ma
and 2 minor) and 5 transient ischemic attacks, all of which occurred only i
the 61 symptomatic patients (8.2%). More recently, Wholey's group 11
reported the results of their international survey on SSCA, which included
2,591 procedures at 24 centers. The overall technical success rate was 98.8
The complication rates of carotid stenting were 3.08% for minor strokes,
1.32% for major strokes, and 1.37% for periprocedural death. The combin
periprocedural stroke and death rate was 5.77% and ranged from zero to 1
among the centers. The restenosis rate was 4.80% at 6 months, as determin
by clinical and diagnostic studies. This survey also revealed that
interventional cardiologists performed 63% of the procedures; radiologists
25%; and vascular surgeons, 12%. At the present time, interventionists at
to 15 centers in the United States perform more than 50% of all carotid
interventional procedures.
Stent-Supported Extracranial Carotid Artery Angioplasty Technique
Several factors can positively influence the results of SSCA:



Preprocedural performance of detailed clinical, noninvasive, and
invasive cerebrovascular evaluation
Appropriate choice of arterial access site
Appropriate choice of guiding catheters, guide-wires, and PTA





balloons
Appropriate choice of stents (balloon-expandable or self-expandab
Use of cerebral protection devices when indicated
Use of essential pharmacologic therapy
Adequate knowledge of or support for intracranial vascular rescue
Postprocedural performance of neurologic, invasive, and noninvas
evaluation
The Choice of Stent
When a stent is placed across the carotid bifurcation, it must adapt to arter
of different diameters. The stent should be in close contact with the arteria
wall in order to allow neointimal growth. Self-expandable stents, such as t
Wallstent® Endoprosthesis (Boston Scientific Corp.; Natick, Mass) (Fig.
and the S.M.A.R.T.™ Stent (Cordis Corporation, a Johnson & Johnson
company; Warren, NJ) (Fig. 2), have varied radial expansion capabilities,
flexibility, and compressibility. Their narrow meshwork is beneficial in
preventing embolism during balloon dilation. The disadvantages of the
Wallstent are less accurate deployment than that of balloon-expandable
stents and sharp strut ends. The S.M.A.R.T. Stent (the acronym S.M.A.R.T
refers to Shape Memory Alloy Recoverable Technology) is a self-expandi
stent made of nitinol (as opposed to cobalt alloy like the Wallstent), and m
have less shortening than Wallstent without the sharp strut ends. Some oth
self-expandable stents that have been used for SSCA are the Memotherm
(CR Bard; Covington, Georgia) and the Integra stent (Boston Scientific).
Currently available stent and balloon designs for SSCA are suboptimal,
because the large profile of the 7-F stent delivery device can cause problem
especially in subtotal occlusions with tortuosity at the site of the lesion. Th
ability to track the stent may be limited by the high-profile delivery system
Nitinol technology is progressing rapidly, and a nondeformable super-elas
memory alloy may become the optimal stent material. In addition, a 5-F
delivery system will soon be the subject of feasibility studies, and cerebral
protection devices integrated with the stents will be available. Both the
S.M.A.R.T. Stent and the Wallstent are now available with smaller outer
diameters of 5.5 to 6 F that allow them to be used with smaller sheaths or
guides.
Some of the balloon-expandable stents such as the Palmaz® Stent (Cordis
offer more precise location capabilities, provide more radial strength, and
contain less metal. The disadvantages of balloon-expandable stents are the
risk of deformity and their tendency to collapse with external compression
trauma. These complications occur at the rate of 4% to 15%. 8–12 For this
reason, most of the interventionists in current trials are using only selfexpandable stents.
Several types of stents have been used successfully for SSCA; however, n
ideal stent is available yet. Several manufacturers are investigating covere
stents, which could inhibit thrombus formation and myointimal proliferati
These coated stents are available outside the United States. However, the
stents require several refinements in diameter and design to be of benefit f
this application. It is possible that the covered stents will decrease the risk
cerebral embolism, but occlusion of the external carotid artery is a potenti
problem. Most investigators agree that SSCA would be of the greatest ben
to patients who are at high risk for surgery, which includes those with









High cervical carotid segmental lesions that are surgically
inaccessible
Tandem lesions with proximal and distal lesions of the internal
carotid artery
Postoperative recurrent stenosis of the carotid artery
Nonatherosclerotic cause of carotid artery stenosis (for example,
fibromuscular dysplasia, Takayasu arteritis)
Ipsilateral stenosis due to prior radiation therapy to the neck
Stenosis due to prior radical neck surgery
Lesions of the common carotid artery with associated internal caro
artery lesions
Increased operative risk due to concomitant illnesses such as
coronary artery disease requiring coronary artery bypass surgery
Contralateral occlusion and high-grade ipsilateral stenosis
Methods of Reducing the Incidence of Cerebral Emboli
Cerebral embolization can be caused by the manipulation of guidewires,
balloons, and stents across complex atherosclerotic carotid artery lesions.
Theron's group 13 analyzed the aspirated blood after patients had undergon
angioplasty under cerebral protection, with the inflated balloon in the inter
carotid artery. They found, in 17 of 21 cases, cholesterol crystals ranging
from 600 to 1300 μm in length. Mathur and coworkers 14 reported that
neurologic complications are related to patient selection. Advanced age (>
years), severe stenosis, and long and multiple stenoses are independent
predictors of procedural cerebrovascular accidents. Mathur's group did no
find any correlation between neurologic complications and preprocedural
symptoms, plaque ulceration, sex of the patient, presence of diabetes
mellitus, coronary artery disease, hypercholesterolemia, prior carotid
endarterectomy, history of smoking, contralateral carotid occlusion, or the
type of stent. Several cerebral protection devices have been developed and
are currently being investigated in an effort to reduce the incidence of
cerebral embolism:




Theron's technique (cerebral protection with occlusion balloon) 13
Kachel's reversing flow technique 15
The PercuSurge® Guardwire™ temporary occlusion and aspiration
system (PercuSurge, Inc.; Sunnyvale, Calif) (Fig. 3)
AngioGuard™ guidewire filter device (Cordis) (Fig. 4)



Medicorp, Henry-Amor-Frid-Rüfenacht (H.A.F.R.) device (Medic
S.A.; Villers les Nancy, France)
MedNova NeuroShield Cerebral Protection System (MedNova US
Topsfield, Mass) (Fig. 5)
EPI Filter Wire™ (Embolic Protection Inc.; San Carlos Calif) (Fig
Theron and associates 13 originally described their technique in 1990, in
which they use a triple coaxial catheter that occludes the internal carotid
artery beyond the stenosis with the use of a latex balloon. Angioplasty and
stent placement are then performed with the patient under cerebral
protection, thus avoiding distal embolism. Any débris from the procedure
be aspirated or flushed through the guiding catheter toward the external
carotid artery. The limitations of Theron's technique include the absence o
guidewire in the shaft of the protection balloon and poor steerability of the
catheter. No large study has yet evaluated this cerebral protection techniqu
Kachel 15 developed a cerebral protection technique that consists of
occluding the upper part of the common carotid artery with a balloon
attached to the distal end of the guiding catheter. The occlusion created by
the balloon allows the reversal of flow toward the external carotid artery.
Angioplasty and stenting can be done through the guiding catheter. This
technique seems easy to use; however, it does not offer sufficient safety
against the risk of embolism. Kachel's series yielded a complication rate o
4.6%, which is not significantly different from complications reported in
other studies that did not use cerebral protection.
The PercuSurge Guardwire (Fig. 3) is a device that consists of a 0.014- or
0.018-inch angioplasty guidewire constructed of a hollow nitinol hypotube
Incorporated into the distal wire segment is an inflatable balloon capable o
occluding vessel flow. The proximal end of the wire incorporates a
Microseal™ that allows inflation and deflation of the distal occlusion
balloon. When the Microseal adapter is detached, the occlusion balloon
remains inflated, at which time angioplasty and stenting are performed. An
aspiration catheter can be advanced over the wire into the vessel, and man
suction is applied to retrieve particulate débris. This device was studied
experimentally in animals by Osterle 16 in coronary vessels and then in
human aortocoronary saphenous vein grafts. 17 These studies showed the
PercuSurge Guardwire to be capable of capturing and retrieving
atherosclerotic and thrombotic débris, which may aid in the prevention of
distal embolism in a vessel. 16
The Medicorp device consists of a protection balloon and a dilation balloo
that can be used over a 0.014-inch coronary guidewire. Although Henry's
group has reported encouraging preliminary data with use of this device,
larger numbers of cases are needed to determine the benefit of this cerebra
protection device. 18 A technique of combined occlusion of the internal
carotid and common carotid arteries could be considered as a reasonable
alternative. Occlusion of the internal carotid artery above the lesion and th
common carotid artery below the lesion would create a dilation zone witho
a flow, which could be aspirated and cleared of atherosclerotic débris easi
Filtering devices are in the early experimental stages for cerebral protectio
Afilter could stop detached embolic particles without interrupting blood fl
to the brain. This technique might benefit patients with contralateral caroti
occlusion or an incomplete circle of Willis who would have no tolerance f
prolonged interruption of ipsilateral carotid flow. The Angio-Guard
guidewire filter device is currently being studied (Fig. 4). Other cerebral
protection devices are undergoing evaluation worldwide to determine thei
ability to prevent cerebral embolization during SSCA (Figs. 5 and 6).
Future Implications for SSCA
The preliminary results of SSCA from several non-randomized trials have
been encouraging. However, randomized clinical trials are necessary to
determine the benefits and the indications for SSCA. Two randomized
clinical trials comparing SSCAwith carotid endarterectomy will soon begi
with the goal of determining which patients would benefit most from each
procedure. The SAPPHIRE (Stenting and Angioplasty with Protection in
Patients at High Risk for Carotid Endarterectomy) trial 19 and the CREST
(Carotid Revascularization Endarterectomy versus Stent Trial) 20 will
randomize high- and low-risk patients with carotid artery stenosis to stenti
or surgery groups. Both trials will use cerebral protection devices in the st
arm of the study.
Top
Abstract
Introduction
Percutaneous Transluminal
Balloon Angioplasty
Carotid Angioplasty
Endoluminal Treatment of
Abdominal ...
Thrombolytic Therapy for
Arterial ...
Vascular Radiation
Therapy
Percutaneous Hemostatic
Puncture Closure ...
Gene Therapy
Covered Stents
Old Devices, New Uses
References
Endoluminal Treatment of Abdominal Aortic Aneurysms
Epidemiology of Abdominal Aortic Aneurysms
Abdominal aortic aneurysm (AAA) is characterized by permanent dilatatio
of the abdominal aorta with a diameter at least 50% larger than normal. Th
serious vascular disorder predominantly affects men who are 60 years of a
or older. Men are affected 5 times as often as women are. More than 90%
AAAs are secondary to atherosclerosis and the majority (89%) are located
the infrarenal aorta. Previous studies have shown that 25% of patients with
AAA who did not undergo corrective surgery died of ruptured aneurysm.
There is a 90% mortality rate associated with an out-of-hospital AAA
rupture, but the mortality rate decreases to 50% for those who undergo
emergency surgery. 21–23 As a preventive measure, over 40,000 surgical
repairs of AAA are performed in the United States annually. 21 The genera
accepted AAA diameter at which repair is indicated is 5 cm. 21–23 The
standard treatment is replacement of the diseased aorta with a prosthetic
graft. The surgical mortality rate in younger (<60 years), asymptomatic
patients undergoing elective resection is 3% to 5%. 21,22 In patients who ha
undergone previous abdominal surgery or who have severe pulmonary,
cardiovascular, or renal disease, the risk of perioperative death ranges from
20% to 60%. Such patients are often denied surgery, because the risks of
surgery exceed the benefits. 21–24
Endovascular Treatment of AAAs
The 1st endoluminal treatment of AAAs in a clinical setting was reported
1991 by Parodi and colleagues. 23 Since then, endovascular exclusion of
AAAs has attracted many specialists: among them, vascular surgeons,
interventional radiologists, and interventional cardiologists. Although
vascular surgeons used to be the main practitioners of aortic grafting, mor
nonsurgical specialists are now getting involved, primarily due to the
development of new transcatheter devices for delivery of vascular prosthe
At first, the use of endoluminal devices was reserved for patients who had
concomitant illnesses or other conditions that increased the risk of
conventional surgery. 23 More recently, endoluminal grafts have been
proposed for use in patients without additional illnesses. 25–30 The 1stgeneration endovascular endoluminal grafts were tubular grafts, and later,
aorto-uni-iliac grafts were developed. The early prostheses were relatively
inflexible and required an introducing femoral sheath with a 24-F internal
diameter. 23 The devices are now available as tube grafts or bifurcated gra
are more flexible, and are available in smaller diameters. Their structures
either completely stent-supported or stented only at the level of attachmen
Some of these devices consist of fabric grafts that are supported throughou
their length by self-expanding metal stents to minimize kinking and
migration. Stainless steel and nitinol (the latter of which has thermal mem
characteristics) are the most common materials used for stents. 26–30
Some investigators have reported that fully supported grafts offer a higher
degree of immediate and late success. 28–30 A stent may be placed on the
outside of the graft material (exoskeleton) 28 or on the inside (endoskeleto
30
The prosthetic wall can be made of a polyethylene terephthalate textile i
woven or knitted form, 28–30 of urethane polycarbonate, or of an expanded
polytetrafluoroethylene (ePTFE) material. The stent grafts are either selfexpandable 28,29 or balloon-expandable. 23 The stent graft is affixed by the
radial force 28–30 of the stent or by a specific attachment system that uses
barbs or hooks. 27 The bifurcated prostheses are available in either a 1-piec
design 27 or a modular design. 28–30 The modular design consists of a
bifurcated prosthesis, which is introduced through the femoral access as th
1st step, followed by insertion of the contralateral limb through the
contralateral femoral access as the 2nd step. Which of these materials and
designs will ultimately produce superior long-term results should be revea
when ongoing clinical studies 26–32 are completed. In 1999, well over 4,00
endoluminal abdominal aortic aneurysm repairs were performed with vari
devices world-wide (Table II). 5–12
Two endoluminal AAA exclusion stent graft systems have received FDA
approval: the Ancure™ Endograft System (Guidant/EVT; Menlo Park, Ca
and the AneuRx™ device (Medtronic AVE; Santa Rosa, Calif). Both are
over-the-wire systems that require bilateral femoral artery access.
The Ancure stent graft (Fig. 7) is an unsupported, single piece of woven
Dacron fabric. The graft is bifurcated and thus has no intragraft junctions.
The main device is delivered through a 24-F introducer sheath; a 12-F she
is required to facilitate the deployment of the contralateral iliac limb. The
graft is attached via a series of hooks that are located at the proximal aorti
end and at both iliac ends. The hooks are seated transmurally in the aorta a
the iliac arteries, initially by minimal radial force, and then affixed by low
pressure balloon dilation. Radiopaque markers are located on the body of
graft for correct alignment and positioning.
The AneuRx device (Fig. 8) is a modular 2-piece system composed of a m
bifurcation segment and a contralateral iliac limb. The graft is made of thi
walled woven polyester that is fully supported by a self-expanding nitinol
exoskeleton. Attachment is accomplished by radial force at the attachment
sites, which causes a frictional seal. The main bifurcated body is delivered
through a 21-F sheath, and the contralateral limb requires a 16-F sheath. T
body of the graft has radiopaque markers that facilitate correct alignment a
positioning.
Endoluminal AAA exclusion has been 90% successful with the devices
currently being used. The need for surgical intervention due to a failed
device is less than 8%. 27–30 The incidence of endoleaks after 1 month has
been less than 10% for most devices, with the incidence at 1 and 2 years
ranging from 15% to 20%. The procedural and early mortality rate was
between 1% and 4% in a recently reported multicenter trial. 31 Rupture du
AAA after endovascular repair is rare: during phases II and III of that sam
clinical trial, no ruptures were reported with use of the EVT device in 597
cases. Nine ruptures were reported with use of the AneuRx device in 1,046
cases during phases I, II, and III. 32
Although substantial improvements have been made in stent grafts since th
original procedure by Parodi and coworkers, 23 further follow-up in curren
trials is needed to determine the exact usefulness of this procedure for the
treatment of AAAs. Some of the devices listed in Table I are currently
undergoing clinical evaluation in the United States, and several have alrea
been released for clinical use in other countries.
Top
Abstract
Introduction
Percutaneous Transluminal
Balloon Angioplasty
Carotid Angioplasty
Thrombolytic Therapy for Arterial Occlusions
A principal goal of treatment for acute limb ischemia is rapid restoration o
blood flow to the ischemic region before the occurrence of irreversible
changes. Surgical treatment of acute limb ischemia, because of
Endoluminal Treatment of
Abdominal ...
Thrombolytic Therapy for
Arterial ...
Vascular Radiation
Therapy
Percutaneous Hemostatic
Puncture Closure ...
Gene Therapy
Covered Stents
Old Devices, New Uses
References
accompanying illnesses, has a 30-day mortality rate of 15% to 25%. 33,34
Intravenous infusion of exogenous plasminogen activators—specifically,
streptokinase—was attempted nearly 40 years ago for the treatment of
peripheral arterial occlusion. 35 Since then, several studies have shown tha
thrombolysis can be an effective initial treatment for many patients who h
acute arterial occlusions. 33–36 One of the advantages of thrombolysis over
surgical intervention is that after thrombolysis, angiographic evaluation ca
uncover hidden causes of the thrombus formation. 33–36 Then underlying
lesions can be identified and treated by transluminal balloon angioplasty o
stenting, or by elective surgical revascularization. 33,34
Reasons for using thrombolytic therapy for arterial thrombotic disease are
listed below:





To remove the thrombus and establish blood flow to the ischemic
limb
To identify hemodynamic causes of arterial or graft occlusion
To convert emergent surgery to elective surgery
To remove thrombus from the collateral circulation
To avoid the mechanical trauma of surgery in the tibio-peroneal
vessels
Thrombolytic agents include streptokinase, acylated plasminogen
streptokinase complex, urokinase (no longer available), pro-urokinase, and
recombinant tissue plasminogen activator (rt-PA-alteplase and r-PAreteplase). All of these agents induce a systemic fibrinolytic state. In
comparative studies on the treatment of arterial thrombosis, 33–41
streptokinase, urokinase, rt-PA, and pro-urokinase have been shown to be
more effective than heparin alone in lysing the thrombus. A retrospective
study from the Cleveland Clinic 37 found that the clinical success rate was
60% for streptokinase, 95% for urokinase, and 91% for rt-PA. A recent
report by McNamara 42 suggests that r-PA may have a clinical efficacy
similar to that of rt-PA, but with less bleeding.
Early studies concerning the use of thrombolytic agents revealed that lysis
more likely to be successful if the thrombosis is recent and involves proxim
vessels. 33–35 Studies of peripheral arterial occlusions have shown that
urokinase has a higher success rate with fewer complications than does
streptokinase. 35,37,39,40 McNamara and Fischer 38 found that the mean
duration of infusion is also significantly shorter for urokinase than for
streptokinase. Comparative studies of streptokinase, urokinase, and rt-PA
have shown that rt-PA provides equal success in thrombolysis, but with a
higher rate of major bleeding. 36,37,39 The use of streptokinase is limited wh
antibodies are being produced due to previous streptokinase use or when t
patient has had a recent streptococcal infection. Urokinase, which had bee
the most frequently used thrombolytic agent, was recently removed from t
market because of concerns about possible hepatitis contamination.
Methods of Administration of Thrombolytic Agents
Thrombolytic agents have been infused both systemically and locally. The
systemic use of thrombolytic agents has been associated with severe bleed
complications. 35,39 On the other hand, some studies 33,34,38,39 have indicate
that the local route (catheter-directed thrombolysis) increases the
concentration of the thrombolytic agent in the treatment area, which
increases the chance of interaction with the thrombus and decreases the
incidence of hemorrhagic side effects. Several investigators have shown th
usefulness of a guidewire traversal test to assess the outcome of
thrombolysis. 34–40 McNamara and Fischer 38 have found that if a guidewir
can easily be advanced through the thrombus before the initiation of
thrombolysis, the thrombus is likely to respond; however, if the guidewire
cannot be passed, thrombolysis is less likely to be successful. A variety of
multi-sidehole catheters and infusion wires are available for local
administration of thrombolytic agents. 39 A coaxial system of 2 catheters o
catheter and an infusion wire are often used to deliver thrombolytic agents
throughout the length of a thrombotic occlusion. 38 This technique shorten
the infusion time and requires less frequent angiographic monitoring,
because lysing is achieved throughout the thrombus and because catheter
repositioning is usually unnecessary. Some of the administration techniqu
that have been tried include bolus lacing (an initial bolus of the agent is gi
over a short period of time throughout the length of the thrombus), 34,38
pulsed-spray (a lytic agent is injected through a multi side-hole catheter
using high-pressure intermittent pulses), 39 and continuous infusion of a
thrombolytic agent over a longer period of time (hours to days). 34–40
Doses of Infusion of Thrombolytic Agents
The dosage and duration of infusion of thrombolytic agents depend on the
indication; the agent used; the route of administration; the amount, age, an
surface area of the thrombus; and the degree of ischemia. In general, the
fresher the thrombus, the more effective the thrombolysis will be. 35,37–39 I
addition, the greater the amount of thrombus (thrombus burden), the longe
will take for the completion of lysis. 38,39 The higher the concentration of t
thrombolytic agent in the area of thrombosis, the more rapid the lysis will
37–39
Several investigators 35,37–39 have recommended the following dosage
regimens for systemic infusion of thrombolytic agents in the treatment of
deep venous thrombosis and pulmonary emboli:


Streptokinase: Administer a 250,000 IU intravenous bolus (loading
dose) over a period of 30 minutes, followed by 100,000 IU/hr for 2
to 72 hours.
rt-PA-alteplase: Administer 100 mg as a continuous intravenous
infusion given over 2 hours for pulmonary embolism and 0.06 mg/


per hour for deep venous thrombosis.
r-PA-reteplase: The dosage recommendations for local infusion of
PA for deep venous thrombosis and arterial occlusions is 0.5 to 1.0
U/hr intravenously for 5 to 24 hours, with or without a bolus of 2 t
U.
Low-dose intravenous heparin (500 U/hr) should be used with rt-P
alteplase and r-PA-reteplase.
The more severe the degree of ischemia, the more important it is to achiev
rapid lysis. Rapidity of thrombolysis is increased by high-dose regimens;
however, the complication rates may also increase. 34,37–39 The duration of
therapy usually depends on the response, as determined by clinical or
angiographic results. Several investigators 37–40 have shown the benefit of
concomitant anticoagulation and thrombolysis. Concomitant anticoagulati
with heparin reduces thrombus formation around the catheter and retards
thrombus propagation and reocclusion of the treated vessel segment,
particularly in a proximal vessel that has low blood-flow above the
occlusion. However, the addition of heparin can increase the severity of a
bleeding complication.
The likelihood of success of thrombolysis depends on the factors listed in
Table III. The end points of thrombolysis are as follows: restoration of
antegrade flow, complete lysis of the thrombus, failure to lyse residual
thrombus, extension of the thrombosis, and complications of therapy.
Patient Selection for Thrombolysis
The selection of patients for thrombolysis depends on the presenting
symptoms, medical history, physical findings, and objective laboratory tes
results. After the diagnosis of thrombosis has been established, it is essent
to evaluate the indications, contraindications, risk factors, and likelihood o
success. If thrombolysis is deemed a reasonable choice for therapy, the sit
of vascular access can be carefully selected and angiography performed.
After the angiographic findings have been evaluated and the likelihood of
success has been determined, the type of equipment and the dosage and ty
of thrombolytic agent can be selected.
Before the initiation of treatment with thrombolytic agents, possible
hypercoagulable conditions should be considered:






Antithrombin III deficiency
Protein C and protein S deficiency
Factor V Leiden level
Anticardiolipin antibodies
Antiphospholipid antibodies
Malignancy
The presence of any of the above conditions is a contraindication to the us
of thrombolytic therapy.
Extensive experience over the past decade has led to increased acceptance
selective intra-arterial thrombolytic therapy for peripheral arterial occlusio
as an adjunct to definitive revascularization procedures. Although newer
infusion techniques have substantially decreased treatment times, they
remain at around 24 hours for lower-extremity occlusions. Work continue
on the optimization of infusion methods and on the development of new
drugs and dosages in order to shorten treatment times.
Mechanical Devices for Thrombus Removal
A number of mechanical devices have been developed to disrupt and remo
freshly formed thrombus from the circulation (Table IV). Only one of thes
devices, the AngioJet® Rheolytic™ Thrombectomy System (Possis Medi
Inc.; Minneapolis, Minn), is currently approved in the United States for us
in the arterial circulation. It appears that these devices are of most value
when used to remove thrombi of recent onset. A brief description of some
the more promising devices follows.
The AngioJet (Fig. 9) is an over-the-wire percutaneous device that remove
thrombus; the tip has a vacuum that operates on the Bernoulli principle.
Several studies 43–47 have shown this device to be effective in treating
thrombus-containing lesions in the peripheral and coronary circulation. It
been used successfully in native arteries, veins, saphenous vein grafts,
prosthetic grafts, and renal dialysis shunts. The AngioJet is currently
approved for use in vessels larger than 2.0 mm prior to balloon angioplast
or stent placement in patients who have symptomatic coronary artery or
saphenous vein graft lesions. It can be used for thrombus removal and for
breaking apart and removing unorganized thrombus from arteriovenous
access.
The Hydrolyser™ Thrombectomy Catheter (Cordis Europa NV; Roden, T
Netherlands) is an over-the-wire hydrodynamic thrombectomy catheter th
uses the Venturi principle for aspiration and removal of intravascular
thrombus. Negative pressure pulls the thrombus into the heparinized saline
stream, resulting in microfragments that are discharged through the outflo
lumen into the collection bag. Early reports from European trials 48,49 sugg
a possible use for this device in thrombus-containing lesions and degenera
vein grafts. Currently, the device is investigational.
The Oasis™ Thrombectomy System (Boston Scientific) is another an over
the-wire hydrodynamic thrombectomy catheter that uses the Venturi
principle for aspiration and removal of intravascular thrombus. This devic
approved in the United States for use in obstructed renal dialysis grafts.
Top
Vascular Radiation Therapy
Abstract
Introduction
Percutaneous Transluminal
Balloon Angioplasty
Carotid Angioplasty
Endoluminal Treatment of
Abdominal ...
Thrombolytic Therapy for
Arterial ...
Vascular Radiation
Therapy
Percutaneous Hemostatic
Puncture Closure ...
Gene Therapy
Covered Stents
Old Devices, New Uses
References
Despite improvements in long-term outcomes after PTA and stenting of th
peripheral vessels, restenosis remains a significant problem—particularly
long lesions, small-diameter vessels, and restenotic lesions. 50 Therapeutic
approaches have focused on mechanical devices, atherectomy, stents, sten
grafts, and pharmaceutical agents. None of these approaches has yet been
successful in solving this problem. 50,51
Vascular radiation for the prevention of restenosis after PTA and stenting
new frontier in the field of peripheral interventions. The 1st experience wi
in vivo endovascular radiation therapy was reported in 1964 by Friedman
and colleagues 52 when they attempted to prevent the development of
atherosclerosis.
Various types of radiation therapy have been tried to prevent restenosis af
angioplasty, stenting, or both (Table V). One consideration is that largediameter peripheral vessels require higher energy sources than the coronar
vessels do. Nori and coworkers 53 have used external beam radiation in the
pilot study, using 8 to 12 GΓ with encouraging preliminary results. To dat
no randomized trial with long-term follow-up after external beam radiatio
has been performed to determine the long-term results and the consequenc
of the radiation to the adjacent tissues.
Intravascular radiation therapy with various beta and gamma sources has
been studied more extensively than has external beam radiation. A large
number of animal investigations 54,55 and a few clinical trials 56,57 have
established the ability of ionizing radiation to inhibit vascular smoothmuscle-cell proliferation associated with restenosis. Recently, several stud
58–60
have shown that localized irradiation of the angioplasty site by
intraluminal delivery of low-dose beta-particle irradiation as well as gamm
irradiation inhibits smooth-muscle-cell migration and proliferation in vitro
and in vivo. 61
A number of isotopes have been tested and several others are being
considered for future studies (Table VI). 62 Such tests have generally
involved the use of high-activity gamma emitters. Two of the most
controversial issues surrounding the delivery of intravascular radiation
involve the preference of beta- or gamma-emitting radioisotope sources an
the importance of source-centering in the arteries. Improper centering of th
catheter-based solid source (off by as little as 0.5 mm) can lead to a dosing
error as high as 5-fold. The consequences of these errors are considerably
worse with beta emitters than with gamma emitters. However, because bet
emitters deposit a large portion of their energy locally, these isotopes have
substantial safety advantages over the gamma emitters for both the operato
and the patient. Efforts to make use of beta radioisotopes in solution await
the development of an appropriate compound with an adequate biodilution
profile to safely handle the potential intravascular release of radioisotopecontaining liquid. 63
Clinical Trials of Endovascular Radiotherapy
The 1st clinical trial involving endovascular radiotherapy was started in 19
by Liermann and co-workers 61 in an effort to reduce the restenosis rate
following PTA in peripheral vessels. Their 6-year experience (May 1990 t
June 1996) was described by Schopohl and co-authors (Frankfurt trial). 62
The study included 28 patients with in-stent restenosis in the femoropoplit
arteries who were treated with a repeat PTA procedure or with directional
atherectomy; all 28 then underwent endovascular radiation with an Ir-192HDR source. The radiation was well tolerated and the investigators report
a 5-year patency rate of 82% based on Doppler ultrasound results. Resteno
occurred in 11% of patients, and 7% of the patients developed thrombotic
occlusion of the treated vessel. More recently, in a randomized trial
comparing PTA and brachytherapy for superficial femoral artery lesions,
Pokrajac's group 63 reported a restenosis rate of 51.7% for PTA alone vers
25% for PTA and brachytherapy combined.
The PARIS (Peripheral Arteries Radiation Investigational Study) trial 64 is
currently evaluating the safety, feasibility, and efficacy of endovascular
brachytherapy to prevent restenosis in the superficial femoropopliteal arte
immediately after PTA without stenting. Endovascular brachytherapy is
administered through a balloon-centering catheter system using an Ir-192HDR source delivered to the target site by a remote afterloader. Twentyseven patients completed Phase II (the 6-month angiographic follow-up).
Their restenosis rate was 11%. 64
Brachytherapy for treatment of peripheral arterial disease to prevent
restenosis after an interventional procedure is in the early developmental
stages. Various isotopes are being tested in an effort to minimize the
radiation exposure to patients and personnel and to reduce the dose delive
in the near field. 61–64 There are now centering balloons that can center the
catheter-based isotope within the lumen of the vessel, in spite of eccentric
plaque. This improves the depth of dose delivery, especially for large vess
New techniques, such as radioactive liquid- or gas-filled balloons that
improve dose delivery, are being investigated. Potential sites for
brachytherapy include the superficial femoral arteries, popliteal arteries,
tibio-peroneal arteries, hepatic vascular system-TIPS (transjugular
intrahepatic portosystemic shunt), arteriovenous dialysis grafts, renal arter
and carotid arteries.
Top
Abstract
Introduction
Percutaneous Transluminal
Percutaneous Hemostatic Puncture Closure Devices
Vascular complications after endovascular treatment can cause morbidity
even death, and can increase the total cost of the procedure by prolonging
Balloon Angioplasty
Carotid Angioplasty
Endoluminal Treatment of
Abdominal ...
Thrombolytic Therapy for
Arterial ...
Vascular Radiation
Therapy
Percutaneous Hemostatic
Puncture Closure ...
Gene Therapy
Covered Stents
Old Devices, New Uses
References
patient's hospital stay. Angiographic and angioplasty procedures involving
femoral artery punctures lead to access site complications in 1% to 9% of
cases. 65 These complications range from simple hematomas to arterial
thrombosis, pseudoaneurysm, embolization, arteriovenous fistula, arterial
hemorrhage requiring transfusion, and extended hospital stays including
possible surgical repair. Krause and Klein 66 estimated a mean cost of $8,0
per vascular complication (assuming a 2-day hospital stay plus surgical
repair in two-thirds of patients with complications). Prevention of vascula
complications is therefore essential to optimize the outcome of interventio
procedures. A variety of devices are available for arterial compression afte
sheath removal, including mechanical clamps and an inflatable pressure
device, the FemoStop™ (CR Bard). These devices are commonly used for
larger sheath sizes (8 to 16 F). The choice of technique is affected by patie
size, the availability of a specific device, and the expertise of the individua
using the device. Arterial compression is time consuming and labor
intensive. The patient is often immobilized for an extended period of time
consequently, back pain and urinary retention may occur. Movement durin
compression can induce a local hematoma. In addition, anticoagulation
therapy must be interrupted for this method of obtaining hemostasis.
Lately, there has been considerable interest in new methods to assist with
hemostasis at the time of arterial catheter removal. This interest stems from
an increased emphasis on patient mobilization and discharge on the day of
the procedure. Recently introduced vascular hemostatic devices, deployab
without compression and anticoagulation reversal, offer an alternative
approach. The role of catheter techniques for arterial entry closure is
evolving. Multiple devices are available, including collagen plugs,
bioabsorbable pledgets, and vessel suturing devices, all of which can be
introduced through specially designed catheters. VasoSeal™ VHD
(Datascope Corporation; Montvale, NJ), the first of such devices, consists
an absorbable beef collagen cartridge delivered in the supra-arterial space
a preloaded, syringe-like system. The collagen, unaffected by antiplatelet
anticoagulant agents, attracts and activates platelets, rapidly forming a glu
like plug at the arterial puncture site and obliterating the subcutaneous
tunnel. Ernst and associates 67 have shown that with the use of collagen
plugs, hemostasis can be achieved in 87% of patients after a mean
compression time of 4.8 minutes. Schrader's group 68 recently reported tha
percutaneously applied collagen plug shortened manual compression time
90%. This reduction in time to hemostasis was independent of the heparin
load. Sanborn and colleagues, 69 in a multicenter randomized trial, found t
major complications occurred in 1.4% of patients after angioplasty when
collagen hemostatic devices were applied.
The Angio-Seal™ Hemostatic Puncture Closure Device (St. Jude Medical
Inc.; St. Paul, Minn) is a specially engineered bioabsorbable anchor (colla
sponge) that is deployed through a sheath, which is then drawn tightly
against the arteriotomy. The device consists of 3 completely bioabsorbable
components: 1) a flat rectangular anchor (2 × 10 mm) made from a
copolymer of polylactic and polyglycolic acids; 2) a 27-mg bovine collage
plug; and 3) a positioning suture of polyglycolic acid that loops through th
collagen plug and the anchor, exiting through the proximal end of the devi
The combination of the anchor with the collagen sponge retained by the
suture forms a mechanical “sandwich” around the arteriotomy. When
deployment of the anchor has been confirmed, the carrier tube and the
insertion sheath are withdrawn and the tamper tube appears. This device is
used to ensure proper positioning of the collagen. Atension spring is then
applied over the suture, the suture is cut, and the carrier tube and the
insertion sheath are removed. All the components are fully absorbed by th
body in 60 to 90 days. This device is available in sizes from 6 to 10 F and
indicated for both diagnostic and interventional procedures. Blengino's gro
70
achieved hemostasis with this device in 90% of patients, with a mean tim
to hemostasis of 2 ± 6 minutes. More recently, in 435 patients, the U.S. ph
II clinical trial 71 showed that both the time to hemostasis and the
compression time were 3.2 ± 10.5 minutes in the Angio-Seal device group
compared with a time to hemostasis of 16.0 ± 12.2 minutes and a
compression time of 19.5 ± 11.9 minutes in the manual compression group
< 0.0001). The overall complication rate was significantly lower in the
device group than in the manual compression group (12% vs 18%,
respectively; p = 0.08), as were bleeding complications (7% vs 15%; p =
0.007) and hematomas (2% vs 6%; p = 0.08%). The incidence of
pseudoaneurysms and arteriovenous fistulae was the same in both groups.
The worst complication associated with the Angio-Seal device is anchor
failure with subsequent distal embolization. Thus far, this complication ha
occurred once in the U.S. multicenter study and twice in the European stud
71
The Angio-Seal clinical trials did not specifically examine the use of thi
device in high-risk patients, such as those who are morbidly obese or who
have severe peripheral vascular disease. Insertion of this device may be
limited in patients who are obese, because the relatively short length of the
tamper tube may make collagen compression difficult. A longer tamper ro
is being designed to correct this problem. As currently designed, the devic
cannot be used during procedures that require catheters larger than 8 F.
Larger sizes are being developed to extend device applicability to procedu
that require larger sheaths. In addition, repuncture of the artery after devic
placement has not been studied in human beings. At this time, the
manufacturer does not recommend reentry into an artery sealed with this
device until 90 days have passed, in order to allow full collagen absorption
In comparison with the Prostar® XL Percutaneous Vascular Surgery devic
(Perclose, Inc.; Redwood City, Calif), the Angio-Seal yielded a slightly
lower rate of immediate hemostasis. Complication rates were similar for b
devices. 72
The Prostar device is now being used in an unusual, off-label fashion that
allows safe percutaneous access and closure of access sites up to 16 F. Thi
method, described by Haas and colleagues 73 and by Krajcer and colleague
74,75
calls for placement of the Prostar device sutures before sheath
placement. The sutures are left untied and the arterial access site is dilated
with sheaths up to 16 F. The artery expands within the confines of the
sutures, which are then closed at the end of the procedure. Howell reported
that this technique, used in more than 54 patients, had a 94% success rate
no lower-extremity complications at the 1- and 6-month follow-up. 74,75
Top
Abstract
Introduction
Percutaneous Transluminal
Balloon Angioplasty
Carotid Angioplasty
Endoluminal Treatment of
Abdominal ...
Thrombolytic Therapy for
Arterial ...
Vascular Radiation
Therapy
Percutaneous Hemostatic
Puncture Closure ...
Gene Therapy
Covered Stents
Old Devices, New Uses
References
Top
Abstract
Introduction
Percutaneous Transluminal
Balloon Angioplasty
Carotid Angioplasty
Endoluminal Treatment of
Abdominal ...
Thrombolytic Therapy for
Arterial ...
Vascular Radiation
Therapy
Percutaneous Hemostatic
Puncture Closure ...
Gene Therapy
Covered Stents
Gene Therapy
The prospect of growing new arteries, both in the coronary and in the
peripheral circulation, generates much excitement. Preliminary results 76 w
the use of vascular endothelial growth factor (VEGF) to induce new blood
vessel formation in animals and human beings have been encouraging. Bo
Baumgartner's and Isner's groups 77,78 have reported that intramuscular
injection of naked plasmid DNA encoding VEGF induces therapeutic
angiogenesis in patients with critical limb ischemia. 77,78 This treatment is
still in the experimental phase.
Covered Stents
Covered stents are a recent development in peripheral vascular therapy.
Originally, it was hoped that the prosthetic covering of the stents would
decrease the restenosis rate, thus providing longer vessel patency. Early
results, however, have shown no benefit over bare metal stents in the
treatment of peripheral stenotic lesions. 79–83 Nevertheless, studies 84,85 hav
shown that covered stents may be very useful in providing an airtight seal
the treatment of such vascular lesions as arterial ruptures, dissections,
aneurysms, pseudoaneurysms, and arteriovenous fistulae. A few of the mo
promising devices are described below.
The Wallgraft™ Endoprosthesis (Boston Scientific) (Fig. 10) is a selfexpanding cobalt super alloy stent covered with polyethylene terephthalate
graft material. The Hemobahn™ Endoprosthesis (W.L. Gore & Associates
Inc.; Flagstaff, Ariz) (Fig. 11) is a self-expanding nitinol stent covered wit
Old Devices, New Uses
References
an ultra-thin PTFE graft. The Jostent® Peripheral Stent Graft (Jomed® US
Conroe, Tex) (Fig. 12) is a single-piece self-expanding nitinol stent covere
with an ultra-thin PTFE graft.
Top
Abstract
Introduction
Percutaneous Transluminal
Balloon Angioplasty
Carotid Angioplasty
Endoluminal Treatment of
Abdominal ...
Thrombolytic Therapy for
Arterial ...
Vascular Radiation
Therapy
Percutaneous Hemostatic
Puncture Closure ...
Gene Therapy
Covered Stents
Old Devices, New Uses
References
Old Devices, New Uses
Top
Abstract
Introduction
Percutaneous Transluminal
Balloon Angioplasty
Carotid Angioplasty
Endoluminal Treatment of
Abdominal ...
Thrombolytic Therapy for
Arterial ...
Vascular Radiation
Therapy
Percutaneous Hemostatic
Puncture Closure ...
Gene Therapy
Covered Stents
Old Devices, New Uses
References
A number of devices that have been around for a while and used primarily
coronary artery interventions are being tried in peripheral interventions.
Techniques such as intravascular therapeutic ultra-sound and laser
angioplasty have not had a marked effect on peripheral interventions. 86–88
One exception is the excimer laser guidewire. Due to its success in crossin
coronary arteries with chronic total occlusion, pilot studies are currently
being carried out to evaluate its effectiveness in totally occluded periphera
arteries. 89
References
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Figures and Tables
Fig. 1 The Wallstent® Endoprosthesis (Boston Scientific
Corp.; Natick, Mass)
Fig. 2 The S.M.A.R.T.® Stent (Cordis Corp.; Warren, NJ
Fig. 3 The PercuSurge® Guardwire™ temporary occlusio
and aspiration system (PercuSurge, Inc.; Sunnyvale, Calif
Fig. 4 The AngioGuard™ guidewire filter device (Cordis
Fig. 5 The MedNova NeuroShield Cerebral Protection
System (MedNova USA; Topsfield, Mass)
Fig. 6 The EPI filter wire™ (Embolic Protection Inc.; San
Carlos, Calif)
Fig. 7 The Ancure™ Bifurcated Endograft System
(Guidant/EVT; Menlo Park, Calif)
Fig. 8 The AneuRx™ device (Medtronic AVE; Santa Ros
Calif)
Fig. 9 The AngioJet® Rheolytic™ Thrombectomy System
(Possis Medical, Inc.; Minneapolis, Minn)
Fig. 10 The Wallgraft™ Endoprosthesis (Boston Scientifi
Fig. 11 Hemobahn™ Endoprosthesis (W.
Fig. 12 The Jostent® Peripheral Stent Graft (Jomed® US
Conroe, Tex)
TABLE I. Endovascular Treatment Methods for Peripher
Vascular Disease
TABLE II. Stent Grafts for Repair of Abdominal Aortic
Aneurysms
TABLE III. Factors Predicting the Success of Thromboly
TABLE IV. Commercially Available Thrombectomy
Devices
TABLE V. Radiation Therapy Methods Used
Experimentally to Prevent Restenosis
TABLE VI. Isotopes Being Tested or Considered for
Endovascular Brachytherapy