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Title page
Proactive surveillance approach to guarantee a functional arteriovenous
fistula at first dialysis is worth.
Hozan Mufty, MD (1), Kathleen Claes, MD, PhD (2) , Sam Heye, MD,PhD (3), Inge
Fourneau, MD, PhD (1)
(1)
Department of Vascular Surgery, University Hospitals Leuven, Leuven, Belgium
(2)
Department of Nephrology, University Hospitals Leuven, Leuven, Belgium
(3)
Department of Interventional Radiology, University Hospitals Leuven, Leuven,
Belgium
Corresponding author:
Fourneau Inge, MD, PhD
Dept. of Vascular Surgery, University Hospitals Leuven
Herestraat 49, 3000 Leuven, Belgium
Telephone:00 32 16 34 68 50 Fax: 00 32 16 34 68 52
Inge.Fourneau@uzleuven.be
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Abstract
Purpose
To evaluate the impact of a proactive surveillance program on functional access rate at
the time of first dialysis.
Methods
In January 2010 a proactive surveillance program to intercept failures to mature was
set up at the University Hospitals Leuven. Patients receiving an AVF for pre-dialysis end
stage renal disease between January 2010 and May 2013 were retrospectively
analyzed. The primary end-point was a functional AVF at first dialysis. Also AVFassociated complications and reinterventions were analyzed. Furthermore, primary,
assisted primary and secondary patency rates were estimated using Kaplan-Meier
survival curves.
Results
One hundred sixty four patients were included in the study. Patients were followed
until first dialysis. Median follow-up time was 287 days (interquartile range, 108 to
551). During follow-up 40 patients (24.4%) needed one or more additional
interventions, resulting in 60 reinterventions. Ten patients needed dialysis within the
minimal accepted maturation period of the AVF (four weeks). Of the 154 patients that
could await the maturation period of the AVF, 145 (94.2%) appeared ready for use at
the time of dialysis or at the end of the study period. In 34 of them (22%), this was
thanks to one or more interventions during follow-up.
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Conclusion
A dedicated surveillance program of patients with AVFs in the pre-dialysis stadium
detects failure to mature. Close coaching and proactive intervention can aid the
patient in his own “fistula first ‘project.
Key words:
Arteriovenous fistulas – Maturation- Dialysis- Functional outcome – End-stage renal
disease
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Introduction
Worldwide, the number of patients developing end-stage renal disease (ESRD) has
increased linearly over the past decades. Diabetes mellitus and arterial hypertension
are the leading causes of ESRD. According to the 2013 United States Renal Data system
annual data report, the majority of patients with ESRD are treated with hemodialysis.
[1] In this patient group, a well-functioning vascular access is of utmost importance.
Autologous arteriovenous fistula (AVF) is the primary choice for vascular access. [2, 3]
At one year, AVF has a comparable cumulative survival rate as to arteriovenous grafts
(AVG), but requires less interventions and has a lower infection rate. [4]
Given these findings, every institution attempts to achieve a high AVF placement rate
in patients with ESRD. However, at time of dialysis initiation many AVFs appear not
usable due to a lack of maturation, inability to needle for anatomical reasons or
thrombosis. [4]
As this happened in spite of regular medical follow-up at the nephrologic outpatient
clinic, we started a dedicated proactive follow-up program for patients after AVF
creation in the pre-dialysis stage. The aim of the program was to optimize the
functional access rate at first dialysis. In this study we investigate how often a failing
AVF could be picked up and remediated, resulting in a functional AVF at the time of
dialysis initiation.
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Patients and methods
1. Patient population
Between January 2010 and May 2013, 215 patients were seen at a dedicated clinic for
AVF in the University Hospitals Leuven, Leuven, Belgium. A total of 167 patients
presented prior to AVF creation in a predialysis stage and are the scope of this study.
Of these, 166 patients presented with ESRD. One patient with hereditary
hemochromatosis was given an AVF for bloodletting. Three patients were not followed
at our dedicated clinic for AVF as they were referred to an external nephrology
department immediately after surgery and were therefore excluded from the study.
This resulted in 164 patients meeting the inclusion criteria of the study.
The study adhered to the principles of the declaration of Helsinki and was approved by
the Ethics Committee of the University Hospital of Leuven. Data were retrieved
retrospectively from the electronic patient files.
2. Dedicated surveillance program
Surgery was performed by one single surgery unit. Prior to AVF creation, the site of
AVF was determined on a clinical basis by the vascular surgeon at the outpatient clinic.
Criteria for choosing the site were based on caliber and quality of the veins, previous
surgery, patient comorbidities and patient preference. In case of major risk factors
(e.g. female, eldery), an upper arm AVF was preferred. When access opportunities
were equal in both arms, the non-dominant arm was preferred over the dominant
arm. Preoperative assessment by physical examination was performed in all patients
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to evaluate the patency and diameter of the superficial venous system and to detect
indirect signs of central venous occlusive disease and evaluate the radial pulse. All
patients had palpable radial pulsations preoperatively. Adjuvant duplex ultrasound or
phlebography were performed when the physical examination was inconclusive. In 17
patients additional duplex (n=3) or phlebography (n=14) were performed because of
an unclear clinical venous anatomy. A three month maturation period was intended
before needling.
Immediately postoperatively, the patient was instructed to palpate the thrill over the
AVF on a daily basis and to come to the emergency department the same day in case
of disappearance of the thrill. Every patient received an information leaflet. Also the
general practitioner was informed.
Patients were seen at a dedicated outpatient clinic at 2 weeks, 6 weeks, 3 months, 6
months and 12 months postoperatively, both by the vascular surgeon and a dialysis
nurse. AVF patency, maturation and functionality were checked by physical
examination of the AVF and ultrasound. Physical examination of the AVF was
performed in two steps. The anastomosis was checked with control of bruit by
auscultation and thrill by palpation. The body of the fistula was checked by the
presence of pulse augmentation, by searching for accessory veins and by the elevation
test as described by Malovrh. [5] The efferent vein was checked for wall thickness,
straightness and depth by ultrasound. Continued AVF monitoring also occurred in
patients with satisfactory physical examinations. In case a stenosis was suspected,
additional duplex and/or fistulography was performed. If indicated, a salvage
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intervention was performed or, when a salvage procedure was not possible, a new AVF
was created. All interventional endovascular procedures were performed by one
interventional radiology service. All surgical procedures were performed by the same
surgical team that created the original AVF. The patients costs weren’t taken into
account in our study because every intervention and outpatient clinic is reimbursed by
the Belgian health insurance.
The primary end point of our study was the presence of a functional AVF at time of
first dialysis. Also AVF-placement-associated complications and reinterventions were
analyzed. Furthermore, primary, assisted primary and secondary patency rates were
estimated using Kaplan-Meier survival curves.
3. Definitions
Primary patency (intervention-free survival) is defined as the interval between the
time of AVF placement and any intervention designed to maintain or reestablish
patency, access thrombosis, or the time of patency measurement. Assisted primary
patency (thrombosis free survival) is defined as the interval between the time of AVF
placement and access thrombosis or the time of patency measurement, including
intervening manipulations designed to maintain the functionality of a patent access.
Secondary patency is defined as the interval between the time of AVF placement until
access abandonment, thrombosis, or the time of patency measurement including
intervening manipulations designed to reestablish functionality in thrombosed access.
[6]
4. Statistical Analyses
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Results are shown as median with interquartile range or means ± standard deviation
unless otherwise specified. Kaplan-Meier survival analysis (WinSTAT® for Microsoft®
Excel) was used to calculate patency rates.
Results
One hundred sixty four patients were included in the study. In 163 the AVF was
created because of ESRD. One female patient was given an AVF for the treatment of
hereditary hemochromatosis. Table I demonstrates the clinical characteristics of the
patients.
The AVF was created in the non-dominant hand in 107 patients (65.2%). One hundred
and four AVFs (63%) were created at the wrist, 60 patients (37%) received their AVF at
the elbow. Table II provides an overview of the various AVF constructions. One
hundred and fifty-one AVFs (92%) could easily be gauged with a coronary dilator of 2.5
mm. Although the vein diameter in the remaining 13 patients was smaller, the AVF was
created for a lack of alternative options. This also occurred in younger patients to
maximize the use of the available veins.
All operations were uncomplicated. Postoperatively, 107 patients (65%) were on
antiplatelet medication or anti-coagulation therapy (acetylsalicylic acid, clopidogrel or
warfarin). The median time until first control was 17 days (interquartile range, 12 to
24). Median follow-up time was 287 days (interquartile range, 108 to 551). Twenty-six
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patients (15.8%) died due to procedure-unrelated causes after a mean of 462 days ±
278 (range 80-981 days; median 384 days) after AVF placement.
Criteria for further exploration at the time of check-up were absent or discrete thrill
and /or bruit, high frequency overtone, positive elevation test, a persistent small
diameter of the efferent vein and a deep or tortuous efferent vein.
During follow-up 40 patients (24.4%) needed one or more additional interventions. In
total 60 reinterventions were performed. Twenty-seven patients (16.4%) underwent
one additional procedure, 10 patients (6.0%) underwent two additional procedures
and two patients (1.2%) four. One patient (0.6%) underwent five procedures, including
a new AVF at the third intervention.
In 31 patients (31/40; 77.5%), 40 reintervention were needed because of failure to
mature. This results in an average of 1.29 interventions per non-maturing AVF. Nine
patients (9/40; 22.5%) needed reinterventions (n=20) because of dysfunction after
initial successful maturation. Numbers and types of intervention are given in Table III.
Patients underwent their first reintervention after a mean of 109 days ± 116 after
surgery (range 2 – 510 days; median 68 days).
Ten patients needed dialysis within the minimal accepted maturation period of the
AVF (four weeks). These patients all received a central venous tunneled cuffed
catheter and were consequently excluded for further follow-up in the study. Of the
154 patients that could await the maturation period of the AVF, 145 of the AVF
appeared ready for use at the time of dialysis or at the end of follow-up, resulting in a
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functional outcome of 94.2%. In 34 of them (22%), this was thanks to one or more
interventions during follow-up. In twenty patients (20/34) a new AVF was created.
Seven patients (7/20) who received a new AVF, needed additional intervention for
adequate maturation. In one patient out of this latter group, an AVG was created
eventually. In 9 patients (5.8%) no functional AVF was available at initiation of dialysis
despite intensive follow-up. Data for AVFs at level of the wrist and at the elbow are
given in table IV. Ninety-five percent (19/20) of the newly created AVFs were created
because of failure of the AVF at level of the wrist.
At the end of the study period dialysis was already initiated in 85 patients; in 66 of
them dialysis could be initiated through a functional AVF after a mean of 305 days
(range 40-979 days; median of 243 days) after creation of the AVF. Seventy-nine
patients with a mature AVF had not yet started dialysis.
Kaplan-Meier estimates for primary patency, assisted primary patency and secondary
patency rate at one year were 67.7% ± 4.2, 82.9% ± 3.4 and 84.6% ± 3.3, respectively
(Figure 1).
Discussion
The aim of our dedicated surveillance program was to optimize the functional access
rate at first dialysis. We succeeded to deliver a functional outcome rate of 94.2%. We
didn’t change our technique to achieve this results. We did it by proactive intervention
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in a rapid fashion to rescue the AVF and by coaching the patient and his surroundings
in the value of this “fistula first project”.
The National Kidney Foundation-Kidney Disease Outcome Quality Initiative (NKFKDOQI) guidelines advise AVF as first access option in long-term dialysis access,
followed by AVG. The use of catheters is discouraged. The NKF-KDOQI guidelines
encourage appropriate planning for the initiation of dialysis therapy with a permanent
access in the pre-dialysis stage. [2, 3]
In an effort to improve outcomes, the rates of autologous AVF have increased in the
US in the last few years. In Europe, its use is even significantly more common. Surgical
training, surgical techniques and postoperative management of AVFs are considered to
be important determinants of AVF outcome. A lower event rate, better AVF salvage
techniques and higher AVF survival rates are observed in Europe. In Europe, the 1-year
AVF survival rate is 83% versus 63% in the United-States. [7]
Timely creation of an AVF is important but many AVFs fail to mature adequately or
develop dysfunction awaiting the first dialysis and patients still end-up with a
dysfunctional AVF at time of dialysis. Consequently, there is a need for interception of
these AVFs in due time and for remediating them. Given these findings and
experiencing this in our own patients in spite of regular medical follow-up at the
nephrologic outpatient clinic, we decided to initiate a proactive follow-up program on
a specialized AVF outpatient clinic for patients with an AVF in the pre-dialysis stage to
optimize the presence of a functional AVF at time of dialysis.
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The fully matured AVF has ideally a superficial, large-caliber efferent vein that allows a
high flow and repeated large-bore punctures. Therefore, several steps have to be
completed. The basis is a good surgical construction, leading to vascular remodelling.
AVF dilatation and vessel wall hypertrophy are end points. Unfortunately, a substantial
fraction of these AVFs fail in their maturation process. [8] This is due to an interaction
between adverse vascular remodeling and hemodynamic forces such as wall shear
stress and transmural or circumferential pressure. [9] A maturation failure rate
ranging from 37 to 61% has been documented in recent studies. [10, 11, 12] The
DOPPS study advises a 95 days maturation time [7], though generally a shorter time is
advised ranging from 3- 6 weeks. [2, 3] AVF thrombosis is easily picked up at the
regular outpatient follow-up, but failure to mature is much harder to detect.
We achieved a failure rate of only 5.8 % with an average of 1.29 interventions / nonmaturing AVF. This is lower compared to published data. Allon et al. compared primary
AVF failure rates of older studies (20-25 years ago) with more recent studies and found
a higher failure rate in the latter one (about 10% vs. 20-50%). They attributed this to a
more liberal selection in creation of AVFs nowadays. The population of patients with
ESRD is becoming older, is more often diabetic with a higher co-morbidity rate. [4] A
rate of 1.7 interventions/AVF has been observed in literature. [13]
The first diagnostic step in the detection of AVF abnormalities is physical examination.
This should include inspection (erythema, swelling, gangrene, change of size over
time), palpation (intravascular pressure along veins, segmental differences in quality of
thrill, skin temperature, pulsation, pain caused by finger pressure) and auscultation
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(typical low-frequency bruit with systolic and diastolic components). Ferring et al
recently published data concerning early postoperative AVF screening at four weeks.
Presence of a thrill and vein diameter ≥ 5mm are sensitive predictors ( 96% and 83%
respectively) for future dialysis use. [13] When physical examination isn’t enough to
deliver a definite diagnosis, further diagnostic steps should be undertaken by duplex
ultrasound as a preferable first and angiography as a next step. [3] In our center 41.4%
of reinterventions required prior duplex ultrasound investigation. In a retrospective
study, Singh et al. controlled the value of ultrasonography in triaging immature AVFs
and found an increase of 47% in maturation to AVFs that where usable for dialysis. [15]
We did not find any similar studies focusing on a surveillance approach of maturing
AVFs exclusively. In 2007, Barone et al. published their results of a dedicated
hemodialysis arteriovenous clinic to provide preoperative evaluation and
postoperative follow-up. Patients in this retrospective study had a follow-up period of
six months, consequently including both immature AVFs and AVFs in use. They had a
final AVF use rate of approximately 85%. Of all AVFs in their study, 38% matured
without any intervention. The remaining 62% underwent an average of 2.2 +/- 0.3
early interventions/dysfunctional AVF. [16]
Another study of Berman et al. published in 2001 focused on an aggressive work-up to
evaluate the impact of secondary procedures to facilitate maturation of AVF and
optimize their use as hemodialysis access. They achieved a functional access in 90% of
the patients and an actuarial primary and assisted primary patency rate at one year of
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78% and 93%, respectively. This study also included both immature AVFs and AVFs
already in use. [17]
Many monitoring and more time-consuming surveillance techniques have been
reported on in literature. However, the sample size of these studies are too small to
demonstrate any beneficial effect. Currently employed monitoring techniques include
physical examination, review of routine laboratory studies, difficulties in cannulation
or achieving hemostasis after cannulation, recirculation, measurement of dynamic
venous pressure. Surveillance techniques on the other hand include access flow
measurement, duplex ultrasound, direct or derived static pressure. Only limited
techniques are available for detection of non-maturing AVF in a pre-dialysis stage. [18]
This implies a need for more reliable control parameters in this subgroup.
The Hemodialysis Fistula Maturation (HFM) study is a large multicenter prospective
epidemiologic study in progress in the United States to evaluate mechanical
hypotheses, to identify clinical practices associated with AVF maturation, to establish
targets for new therapeutic interventions and to assess the predictive value of early
indicators of AVF outcome. [19]
Repeated interventions to promote AVF maturation are associated with an increase in
interventions to maintain access patency once dialysis has started. These repeated
interventions are also associated with a decreased cumulative AVF survival rate in the
long term.[20] The question remains whether these reinterventions are worth or
whether these salvaged AVFs should be left untouched and be considered as complete
treatment failures? We can compare our data with data of a recently published study
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by Verest et al in Acta chirurgica Belgica. Between January 2005 and December 2009,
344 patients received a AVF in the University Hospitals Leuven by the same surgeon as
in our study. When we only consider the group of patients still in a predialysis stage
(n=78) after six months of follow-up, 27% (21/78) underwent additional intervention.
Twenty-two percent of the patients (17/78) received a new fistula whom 15 (19%)
without preceding intervention on the failed AVF. [21] In our present study, only
12.9% (20/154) of the patients received a new AVF as many of the dysfunctional AVFs
could be solved. Twenty-four percent of the patients needed one or more additional
interventions. In the study of Verest et al, 1-year primary and secondary patency rate
were 64% and 77% respectively, whereas in the present study a 1-year primary
patency of 67.7% and secondary patency of 84.6%.is achieved.
We managed to achieve a mature AVF ready for use in 94% of patients. Our dedicated
surveillance program was led by a surgeon skilled in proactive interventions and our
patient was taught to recognize a well functioning AVF. By taking enough time for
every patient, this study turned out into a successful surveillance program with good
results in which we avoid the additional morbidity (infection and thrombosis) of
tunneled cuffed venous catheters. [3]
Conclusion
With this strict surveillance program, a functional success rate of 94.2% was achieved,
in 22% of AVF, this was thanks to one or more interventions during follow-up. We
suggest that the implementation of a dedicated surveillance program of patients with
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AVF in a pre-dialysis stage is essential for every dialysis unit as failures to mature are
often not picked up at a regular medical follow-up.
Disclosures
There are no disclosures
List of figures:
Figure 1: Kaplan-Meier survival analysis of the first event-free survival (primary patency),
assisted primary patency and AVF survival (secondary patency)
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Table I: Clinical characteristics of patients
Clinical characteristics
N
AVF localization
Wrist (N=105)
Age (Years): Mean ± SD (range; median)
Elbow (N=59)
65± 14.4
63±14.8
70±12.3
(21-89; 68 )
(21-86; 66)
(27-89; 73)
97 (59%)
70 (67%)
27 (46%)
Female: N (%)
67 (41%)
35 (33%)
32 (54%)
BMI: mean ± SD (range; median)
26.8 ± 5.7
26.9±5.9
26.7±5.3
(14.5 – 54.9; 25.6)
(14.5-54.9; 25.6)
(17.5-46.8;25.8)
28 (17%)
20 (19%)
8 (13%)
Stopped > 10years: N (%)
25 (15%)
17 (16%)
8 (14%)
Stopped < 10years: N (%)
14 (9%)
8 (8%)
6 (10%)
Never smoked: N (%)
97 (59%)
60 (57%)
37 (63%)
13 (8%)
8 (8%)
5 (9%)
50 (30%)
35 (33%)
15 (25%)
Peripheral arterial disease: N (%)
49 (30%)
29 (28%)
20 (34%)
Previous AVF: N, (%)
4 (2%)
2 (2%)
2 (3%)
Cause of ESRD: Diabetes: N (%)
41 (25%)
29 (28%)
12 (20%)
Glomerulonephritis/vasculitis: N (%)
31 (19%)
22 (21%)
9 (15%)
Hereditary/congenital: N (%)
20 (12%)
13 (12%)
7 (12%)
Tubulo-interstitial: N (%)
10 (6%)
5 (5%)
5 (9%)
Hypertensive/vascular: N (%)
30 (18%)
21 (20%)
9 (15%)
Miscellaneous: N (%)
4 (3%)
1 (1%)
3 (5%)
Unknown: N (%)
27 (17%)
13 (12%)
14 (24%)
Gender: Male: N (%)
Smokers: Active: N (%)
Diabetes Mellitus type 1: N (%)
type 2: N (%)
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Table II : Summary of AVF constructions
Level
Construction
N (%)
wrist
Radio-cephalic AVF (RCAVF)
104 (63)
elbow
Radio-cephalic AVF (RCAVF
19 (12)
Radio-median cubital AVF
16 (10)
Brachio-basilic AVF (BBAVF)
9 (5)
Brachio-cephalic AVF (BCAVF)
7 (4)
Brachio-median cubital AVF
5 (3)
Radio-basilic AVF (RBAVF)
3 (2)
Ulno-median cubital AVF
1 (1)
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Table III: Numbers and types of reintervention
Type of intervention
Endovascular
%
N
30.0
18
Angioplasty
17/18
Thrombectomy &
1/18
angioplasty
OPEN
70.0
42
Thrombectomy
7/42
Superficialization &
7/42
lateralization
Branch ligation
4/42
Re-anastomosis
3/42
New AVF
20/42
PTFE AV-loop
1/42
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Table IV: Data for AVFs at level of the wrist and at the elbow
AVF lokalisation
Wrist: N (%)
Elbow: N (%)
Start dialysis with catheter
7/98 (7.1%)
2/56 (3.5%)
AVF ready for dialysis at end of follow-up
91/98 (92.8%)
54/56 (96.4%)
Creation of new AVF after first event
15/98 (15.3%)
0/56 (0%)
Creation of new AVF (total)
19/98 (19.3%)
1/56 (1.7%)
Patients with need for HD within normal accepted maturation period were omitted in these data
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