Echocardiography of Prosthetic Valves
Dr. Tehrani
Different Types of Valves
Homografts (allograft)
Cadaveric human aortic and pulmonary valves
Heterograft (Xenograft)
Prosthetic Valves
Bioprosthetic valves
Pig aortic valve
Bovine pericardial (other)
Mechanical
Urethane ball in a cage
Single or multiple discs
Homografts (allograft)
Homografts
Homograft Valves
Harvested soon after death w/ the
endothelium still viable
Preparation for implantation
Storage in ABX
Cryopreservation (more recently)
No anticoagulation
Low incidence of endocarditis
Failure due to gradual aortic incompetence
Homografts
Position
Mitral
Fitted w/ stent, not proved successful
(high failure rate at 5 years)
Stentless grafts not an option for MVR
Aortic
Stentless


Subcoronary
Root Replacement
Echocardiography of Stentless Aortic
Homografts
Doppler flow characteristics similar to native valve.
Only 2-D evidence: Increased Echo intensity, and Thickness of aortic
annulus.
Stentless Heterografts
(Xenograft)
Stentless Heterografts (Xenograft)
Same utility as
allografts for AVR:
Subcoronary
implantation, and
Root replacement
Advantage over
allografts is wider
availability
Durability is at least as
good as allografts
Prosthetic Valves
Prosthetic Valves
Bio-Prosthetic and Mechanical Prosthetic
All Prosthetic valves have a sewing ring
anchored to the native tissue with sutures
The occluding portion of the valve:
Tissue leaflets  Bio-Prosthetic
Single or multiple discs/ Urethane ball in a cage
 Mechanical Prosthetic
Bio-prosthetic Valves
Bioprosthetic Valves
Two types, of
occluding mechanism
1. Porcine aortic valve
(the valve size of
the biggest pig is
limiting)
Hancock, and
CarpentierCarpentier-Edwards bioprosthesis
Edwards
bioprosthesis
Bioprosthetic valves
2. Bovine Pericadium
leaflets are shaped to
size.
More choices
Echocardiographiaclly
these two valves
types are
indistinguishable.
Ionescu-Shiley
(1976)
Bioprosthetic valves
Mitral Position
2-D ECHOCARDIOGRAPHIC APPEARANCE
Bioprosthetic valves
Aortic Position
2-D ECHOCARDIOGRAPHIC APPEARANCE
Bioprosthesis
Used extensively in a variety of sites:
Aortic
Mitral
Tricuspid
Advantage:
Low thrombogenicity => No anticoagulation
Bioprosthesis
Disadvantages:
Less durable than mechanical prosthesis
Mitral position worse
Due to greater backpressure gradient
Dysfunction:
Leaflet thickening, and Ca++
Fracture, tears, or progressive stenosis
In vivo, roughly 10% of normal bioprosthetic
valves have some leakage.
Overview of Various Devices
Bio-Prosthetic Valves
Mechanical Prosthetic Valves
Mechanical Vlaves
Ball-and-Cage Valves
Tilting disc Prosthesis
Single disk
Bileaflet
Mechanical Prosthesis
The occluding mechanism dictates both:
The echocardiographic appearance of the
valve, and
The flow pattern through the valve
To assess performance, the type of valve
implanted must be known
Ball-and-Cage Valves
First implanted by starr
and Harken in 1960.
Ball-and-Cage Valves
Opening and closure of the ball-valve
Ball-and-Cage Valves
Axisymmetric flow
around the valve.
Stagnant flow in
the shadow of the
ball.
Ball-and-Cage Valves
Doppler assessment at the margins of the ball
Ball-and-Cage Valves
M-Mode assessment of Ball-Cage Valve
Ball-and-Cage Valves
Durable
Mitral position
Satisfactory profile with the largest size (34 or
32 mm diameter devices)
Can affect the interventricular septum
Aortic position
Small prosthesis required, which can be
associated with significant gradient
Regurgitation limited to closure backflow.
Tilting Disc Prosthesis
All essentially similar consisting of
Circular prosthetic material, and
One or two hinged and mobile disc(s)
Disc attachment to the ring is eccentric
Closure occurs by backpressure on the
largest portion of the disk
Single Disc Prosthesis
Single Disc devices:
Hall-Medtronics monostrut
Bjork-Shiley
Opening arch is 55-70 degrees
Flow orifice:
Major and minor flow
orifices
Streamlines of flow passing
through the sewing ring and
then laterally out and
around the prosthetic disc
Single Disc Prosthesis
Bjork-Shiley
Standard
Convex-concave
Many other variations in the
market
All of these devices have a
zone of stagnation behind
the disc  thrombus
formation
Single Disc Prosthesis
Bjork-Shiley in the
Mitral position
Single Disc Prosthesis
Leak around:
Central strut
Dominant jet
Between the occluding disc
and sewing ring.
Two smaller peripheral jets
Normal hemodynamics
Reg.Frac. approx. 12%
Tachycardia, and low output
Reg.Frac. upto 37%
Single Disc Prosthesis
Single Disc Prosthesis
Dysfunction
Gradual ingrowth of fibrous tissue (panus)
Flow obstruction
Intermittent sticking of the valve with
associated flash pulmonary edema
Bileaflet Mechanical Prosthesis
St. Jude prosthesis
The most commonly used.
Two equal sized semi-circular
leaflets attached by a midline
hinge.
Discs can tilt in excess of 80
degrees, resulting in larger:
Orifice area
Bileaflet Mechanical Prosthesis
St. Jude prosthesis
The most commonly used.
Two equal sized semi-circular
leaflets attached by a midline
hinge.
Discs can tilt in excess of 80
degrees, resulting in larger:
Orifice area
Regurgitant back flow
Bileaflet Mechanical Prosthesis
Regurgitation occurs at the disc margins
The regurgitant jets converge toward the center of the valve
Bileaflet Mechanical Prosthesis
St. Jude valve in the mitral position.
Imaging of Prosthetic Valves
Special Problems of 2-D Imaging
Artificial Valves
Echocardiographs are calibrated to measure
distance based on the speed of sound in tissue.
Prosthetic valves have different acoustic properties
than tissue. Hence, distortion of:
Size
Location, and
Appearance, of the prosthesis.
Special problems of artificial valves
Intense reverberation, and
Shadowing
Less gain leads to less:
Reverberation, and
Shadowing, as well as
Better visualization of non-biologic
components of the valve
HOWEVER 
Decreased definition of cardiac structures
Special problems of artificial valves
First image at normal settings, then
Reduce the gain to interrogate the
leaflets of Bio-prosthetic valves.
Utilize multiple views.
Prosthetic Valve Pathology

Prosthetic Valve Stenosis



Aortic
Mitral
Prosthetic Valve Regurgitation


Aortic
Mitral
GENERALLY
Prosthetic Stenosis (and Regurgitation) is:
 A question of degree,
 Not a question of whether.
Prosthetic Valve Stenosis
Determinants of gradients across normal
prosthetic valves include:
Valve type, i.e., Manufacturer
Valve size
Flow through the valve
Wide range of “Normals”
Aortic Prosthesis Gradients as a
Function of Valve TYPE and SIZE
Dependence on:
Valve type,
and
No.21
Size
No.27
Gradient as a Function of Valve Type
Normal Dopplar data in patients with various types of prosthetic valves in
the Aortic Position
Gradient as a Function of Valve Size
Valve specifications and doppler echocardiographic data in 67 St. Jude
medical valves in the Aortic position
Chafizadeh ER, Circ. 83:213, 1991
Gradient as a Function of Flow
I.
Valve type, i.e.,
Manufacturer
II. Valve size
III. Flow through the valve
No.21
Indicies of Valve Stenosis which are
Less Flow Depenent
A.
B.
C.
D.
Contour of jet velocity
Doppler velocity index
Effective orifice area
Valve resistance
A-Contour of the jet velocity
With prosthetic
obstruction there
is:
Late peaking of
the velocity,
More rounded
contour,
Prolonged
ejection.
B-Doppler Velocity Index
DVI= Pk VelLVOT/Pk Veljet
Flow independent
0.2 – 0.27 cutoff for critical stenosis
Caveat:
Pressure recovery
To be discussed …
C-Effective Orifice Area
Continuity Eqn.
EOA CSALVOT TVILVOT TVIjet
Caveat:
Pressure recovery
To be discussed …
D-Valve resistance


VR  Grad. SEP x 1.33
At cutoff of 280 dynes.sec.cm5, best at
differentiating AS, from NL (Zoghbi et al.)
Special Caveats Re:
Overestimation of Gradients
Two scenarios:
I.
The velocity upstream from the valve is not
negligible in application of the Bernoulli Eqn.

P  4 V 2  V 1
2
2

Usually in AV when proximal velocity on
the LVOT is > 1.5 m/s
…Overestimation of Gradients
II. Central acceleration with
the St. Jude valve:
Increase of velocities
(and gradients) is
created at the level of
the valve through the
smaller central orifice.
Most significant with:
High flow states
Small valves
…Overestimation of Gradients
Central acceleration with
the St. Jude valve:
CW Doppler records
these high velocities.
Catheter-derived
gradients show
pressure recovery at
30mm downstream from
the valve.
Indicies which are Less
Flow Dependent, BUT…
A.
B.
C.
D.
Contour of jet velocity
Doppler velocity index
Effective orifice area
Valve resistance
Clearly, both of
These Parameters
Will be Affected by
The Pressure
Recovery
Phenomenon.
Prosthesis-Patient Mismatch
Mismatch
Rahimtoola 1978:
“Mismatch is present when the effective prosthetic
valve area, after insertion into the patient, is less than
that of a normal human valve.”
By definition:
Some such “mismatch” will almost always be present.
Mismatch
EOA Index
 0.85 cm 2/m2
Literature identifies the above
as a cut-off for mismatch
Mismatch



BSA  wt.0.425 hgt.0.725 x 0.007184
This is the EOA that
The patient physiologically
Needs.
Next locate the published
in-vivo EOA of the valve
used.
Mismatch
Not the company reported data
JACC Review Article, 10/2000
Prosthetic Valve Pathology

Prosthetic Valve Stenosis


Aortic
Mitral
Mitral Prosthesis Stenosis
Parameters used for assessment of
function:
A. PHT/Area by PHT
B. Effective Orifice Area by continuity
C. Mean gradient
Mitral Prosthesis Stenosis
A-PHT/Area by PHT
Not expected to yield accurate valve area
The empiric constant of 220 validated
for the geometry of rheumatic MS
Useful in longitudinal follow-up of valve Fx
Should not be used when diastolic filling
period is short (fusion of E and A)
Tachycardia
Long first degree block
Mitral Prosthesis Stenosis
B-Effective Orifice Area by continuity Eqn.
One underlying assumption is absence
of significant AI or MR
Physiologic prosthetic MR 10-30%
(Medtronic-Hall, significant central MR,
specific design feature  less
thrombogenic)
Mitral Prosthesis Stenosis
C-Mean gradient,
function of:
Size
Type of
prosthetic
Flow
Heart rate
(should also be
reported when
evaluating MVA)
Prosthetic Valve Pathology

Prosthetic Valve Stenosis



Aortic
Mitral
Prosthetic Valve Regurgitation


Aortic
Mitral
Prosthetic Valve Regurgitatoin
Two issues:
Physiologic v.s. Pathologic regurgitation
TTE v.s. TEE for assessment of
regurgitation
Prosthetic Valve Regurgitation
Physiologic Regurgitation
Early onset and brief duration
Reflects backflow from closing movement
of occluding device
Tilting disc and bileaflet valves have
additional late backflow leakage
Intended to reduce risk of thrombosis
Aortic Prosthesis Regurgitation
Criteria similar to grading native valve
AI:
Jet width
PHT < 350
Holodiastolic flow reversal
Regurgitant fraction>40%
Mitral Prosthesis Regurgitation
TTE of limited value in assess MR due to
acoustic shadowing of the LA
Doppler findings suggestive of severe MR
E wave > 1.9 m.s
PISA
Short isovolumetic relaxation time
TVILVOT/TVIPr-MV < 0.4