Evaluation of the Endovascular Salvage Outcome for Dysfunctional Arteriovenous Fistula for Hemodialysis According To the Site of the Lesion: 3 Years Experience-Juniper Publishers
JUNIPER PUBLISHERS-OPEN ACCESS JOURNAL OF CARDIOLOGY & CARDIOVASCULAR THERAPY
Abstract
Background: Percutaneous
transluminal angioplasty (PTA) has become an established treatment of
dysfunctional arteriovenous fistula (AVFs). The outcome of such
intervention is significantly influenced by the site of the underlying
lesion.
Aim of the study: To focus on
the impact of the site of the lesion(s) tackled on the immediate and
delayed outcomes of endovascular salvage of dysfunctional AVFs in terms
of technical success and 6 month patency rate; aiming at significant
improvement in the management plan.
Patients and methods: This
prospective study was carried out since January 2012 through August
2015. The study included 253 hemodialysis patients; 147 (58.1%) males
and 106 (41.8%) females with a mean age of 58 ± 15 years. All patients
had dysfunctional native AVFs that were subjected to endovascular
salvage. The outcomes were evaluated in view of the site of underlying
lesions.
Results: The dysfunction of the
studied AVFs was caused by an underlying single lesion in 225 (88.9%)
cases; while multiple lesions were found in 28 (11.1%) cases. The
commonest site of lesions was encountered in the venous
juxta-anastomotic segment 76 (30%) and venous needling segment 61
(24.1%). Technical success was achieved in 231 (91.3%) patients.
Recanalization was best achieved through trans-radial access in 191
(75.4%) AVFs. Balloon angioplasty successfully recanalized 216 AVFs,
while stenting was needed in 15 patients. No major complications have
been recorded. Follow up period ranged from 6-20 (mean 8 ± 5.3) months.
The overall primary patency rates were 88.3% and 71.4% at 1 and 6 months
respectively. Technical success and patency rates were recorded
according to site stratification.
Conclusion: The site of the
lesion has an impact on the outcome of endovascular salvage of
dysfunctional AVF with variable immediate success and later patency
rates. Arterial and central venous lesions have the least success and
patency rates. However, unfavorable rates are not an invitation to
regret from paying effort for salvage. Simply, because intervention can
be repeated, and more importantly, the use of suitable tools and
techniques can optimize the results according to each lesion site.
Abbreviations: PTA: Percutaneous Transluminal Angioplasty; AVFs: Arterio-Venous Fistula; HD: Hemo-Dialysis; ESRD: End-Stage Renal Disease; PSVR: Peak Systolic Velocity Ratio; NIH: Neointimal Hyperplasia
Introduction
The provision of hemodialysis (HD) for patients with
end-stage renal disease (ESRD) requires a well functioning vascular
access [1]. The best access for HD is the one that suit every patient
individually. Durability is the concerned criterion in whatever the type
of the access is. Under such heading comes the word “patency” whether
primary, assisted primary, or
secondary. Among the available accesses, the native AVF stands as the
option with better overall patency and lower complication rates.
However, when dysfunction is encountered in them, this represents a
major cause of morbidity, mortality and significant HD care-related
costs [2].
Until the near past, a dysfunctional AVF was
synonymous with a temptation to decide a new access with resultant
numerous procedures to maintain a safe HD and eventual exhaustion of all
access sites. The introduction and evolution
of endovascular techniques hold promise to salvage these AVFs
that is to transform non-maturing, stenosed, or thrombosed
fistulas to functioning fistulas again [3,4]. The site of lesion
responsible for AVF dysfunction is a crucial factor from different
aspects regarding the pathology, clinical presentation, and the
way & outcome of treatment. Such lesions might be confronted
in the arterial side, anastomotic, or in the venous side with
variable site stratifications. The aim of this study is to focus on
the impact of the site of the lesion(s) tackled on the immediate
and delayed outcomes of endovascular salvage of dysfunctional
AVFs in terms of technical success and 6 month patency rate;
aiming at significant improvement in the management plan.
This prospective study was conducted mainly in Kasr El
Aini - Cairo University hospitals since January 2012 through
August 2015. It included 253 HD patients with dysfunctional
native AVFs. They were 147 (58.1%) males and 106 (41.8%)
females. Their mean age was 58 ± 15 years. Dysfunctional
autogenous AVFs belonged to one of three common upper limb
types whether radiocephalic, brachiocephalic, or brachiobasilic
fistulas. Patients with persistent hypotension, associated
infection, overlying skin integrity disruption, or known contrast
allergy were excluded from the study.
All patients were scheduled for endovascular salvage of
their dysfunctional AVF after proper clinical and radiological
assessment in one hand and after obtaining the ethical approval
from the faculty research committee and informed written
consent from the patients in the other hand. Clinical assessment
included revision of the main presentation then assessment of
the targeted upper limb in general, and the fistula in particular.
The upper limb was evaluated for blood pressure, pulsations,
scars, upper limb oedema, and the presence & distribution of
dilated veins. The current fistula was evaluated regarding its
type, duration since creation, time lapse since dysfunction or
cessation, aneurysmal dilatation, thrill propagation, overlying
“water hammer” pulsations, and venous thrombus load as
detected by palpation.
Radiological assessment was done for all patients. The
protocol was to visualize the arterial tree starting from the
subclavian down to the radial and ulnar arteries then assessment
of the anastomotic site and the outflow up to the subclavian
and/or the innominate veins. Duplex assessment targeted three aspects:
- The lesion morphology including number, site, severity, and length of each lesion,
- The current access hemodynamic including flow rate (vessel cross sectional area x mean velocity), peak systolic velocity (PSV), and Peak systolic velocity ratio (PSVR), and
- The suitability of the radial artery as an endovascular access (caliber, origin from the brachial artery, and its relative contribution with ulnar artery in hand circulation).
The scope of clinical and radiological assessment was centered
on the exact site of the lesion(s). Accordingly, lesions were
stratified as: arterial (Proximal), arterial (Juxta-anastomotic),
anastomotic, venous (Juxta-anastomotic), needling segment,
junctional (Entry of the fistula vein into the deep system), and
central venous lesions. Endovascular AVF salvage was offered
for all patients using standard endovascular techniques via the
trans-radial, trans-venous, or less commonly trans-brachial
approaches. Femoral venous approach was occasionally needed
in certain situations. Two or more endovascular accesses were
mandatory in some cases. Standard balloons were used in most
of patients unless encountering non-dilatable persistent lesions
where high pressure balloons were used. A hybrid procedure
was needed in some cases when an open thrombectomy was
added to deal with heavy venous thrombus load or when an
acute arterial occlusion unintentionally ensued while dealing
with juxta-anastomotic lesions. Self expanding stents were used
in recanalized central venous lesions.
The parameters of successful procedure were defined by
- Anatomic success: restoration of luminal diameter with less than 30% residual diameter stenosis.
- Clinical success: improvement of clinical parameters with at least 3 sessions of successful HD, and
- Hemodynamic success: the restoration of hemodynamic parameters (PSVR˂2) [5-9].
Unless contraindicated, Enoxaparin Sodium twice daily
S.C and Hirudin cream QDS topically were used routinely in
successful cases for 5 days. Uneventful patients were advised to
use their salvaged fistula for dialysis in the next day after the
procedure and followed up after 1 week, 1 month, 3 months, and
6 months regarding the efficiency of dialysis, primary patency
rate, and incidence of complications. All the data were collected
and presented as mean, standard deviation, and percentages.
Results
A total of 253 patients (147 males and 106 females) were
included in the study. Their mean age was 58±15 years (range,
12-65 years). Co-morbidities included hypertension (66.7%),
diabetes (47%) and coronary artery disease (26%). The most
common clinical presentations for dysfunctional AVF were
inability to puncture the vein (41.5%) and prolonged bleeding
after needle withdrawal (27.6%). The target lesions were
confirmed by duplex assessment and were considered significant
if the stenosis exceeded 50% of normal vessel diameter [5]
(Table 1).
The mean duration since AVF creation to first intervention
was 7.9 ± 7.5 months (range 2.5 to 46 months). The type of
dysfunctional AVF was either radiocephalic, brachiocephalic,
or brachiobasilic in an incidence of 59.6%, 30.8%, and 10.2%
respectively. The dysfunction of the studied AVFs was caused by
an underlying single lesion in 225 (88.9%) cases while multiple
(≥2) lesions were found in 28 (11%) cases; as 23 (9.1%) cases
had 2 lesions and 5 (1.9%) had 3 lesions. The most commonly
involved site was detected in the juxta-anastomotic segment,
while the least common site was found in the proximal arterial
segment (Table 2) (Figures 1-3).
Trans-radial access was solely the route of choice in 135 (53.3
%) AVFs, and in combination with other access in 56 (22.1%) AVFs. Trans-venous access (through venous limb of the AVF)
was resorted to in 61 patients (24.1%) when a segment of the
venous outflow tract was still patent distal to the anastomosis
site especially when there was a limitation to puncture the radial
artery. Double trans-venous access was needed in 27 patients
(10.6%) having total occlusion of their venous outflow tract; one
was directed towards the anastomosis and the other was directed
towards the central venous outflow with an overlapping segment
in between, (Figure 4). Trans-femoral access was needed mainly
in patients with central venous occlusions especially when an
ante-grade wire crossing had failed, (Figure 5).
Anatomic success was achieved in 231/253 (91.3%) patients;
whether directly through recanalization of the whole fistulous
tract (n=219) or through recanalizing part of it then diverting
the blood flow to a patent deeper vein (n=12) (Figure 6).
Balloon angioplasty using standard balloons could successfully
recanalize 216 patients. High pressure balloons were mandatory
in 14 cases (Figure 7). Fifteen self expandable stents were used
in those with central venous lesions (Figure 8).
Venous thrombectomy of heavy thrombus load was
needed in 11 patients; additionally 2 of them required arterial
thrombembolectomy due to the development of an acute
ischemic episode while managing a venous juxta-anastomotic
lesion and the procedure was successfully completed. The
technique has failed in 22 (8.6%) patients. The most common
cause was failure to cross the lesion in 13 AVFs; (Eight patients
with central, and 5 with peripheral venous lesions). Other
reasons included persistent false passage (n=3), uncontrollable
rupture (n=2), resilient non-dilatable lesion in spite of high
pressure balloon dilatation (n=2), immediate vascular steal
(n=1), and contrast allergy (n=1).
Other complications included minor hematoma that was
encountered in 7 patients who were managed conservatively.
Another 2 expanding hematomas necessitated ligation of the
fistula. A circumferentially ruptured balloon material required
extraction while performing a successful PTA for radio cephalic
AVF (Table 3).
All 231 patients whose AVFs were salvaged successfully were
followed up for a minimum of 6 months with a mean follow-up
duration of 8 ± 5.3 (range 6-20) months. The fistula had to be abandoned due to occlusion or dysfunction during dialysis in
30 (12.9%) of the 231 patients. Fifty eight (25.1%) patients
required a total of 77 repeat endovascular treatments as 2ry
PTAs that were performed for single stenosis in 25 AVFs and for
multiple stenoses in 33 AVFs [6-9]. The overall 1ry patency rate was 88.3% and 71.4% at 1 and 6 months, respectively. In single
lesions´ AVFs, 1ry patency rates were 90.3% and 75.4% at 1 and
6 months respectively; while in multiple lesions´ AVFs, the 1ry
patency rates where 69.5% and 34.7% respectively (Table 4).
The superiority of autogenous AVFs in general when
compared with artificial grafts and dialysis catheters is well
documented in the literature [10,11]. Although better patency
is the keyword; yet, an incidence of some failures among them
are there. This can be attributed to the development of stenoses
leading to their dysfunction that eventually ends by either
reintervention or creation of a new fistula [12]. Reintervention
using the PTA strategy offers a chance for salvage of the current
dysfunctional AVFs with sparing of the other possible venous
sites especially if their number is limited [13]. The collaboration
of several factors contributes in the high likelihood of occurrence
of stenoses in an autogenous AVF.
It is believed that the mere establishment of anastomosis
between a high-pressure arterial system and a low-pressure
venous one is sufficient to generate tangential wall shear stress,
compliance mismatch, and flow turbulence throughout the
circuit [14]. All these mechanical factors impart a biological
response “mechanotransduction” leading to continuous
neointimal hyperplasia (NIH) formation [15-19]. A more popular
explanation for the liability of juxta-anastomotic segment to stenosis is that dissection, mobilization, and swinging during
AVF creation might deprive it from its blood supply [20-23].
However, similar circumstances for the dissected re-tunneled
basilic vein don’t end into the same consequences. In the current
study, venous juxta-anastomotic segment being the seat of
considerable degree of mechano transduction and hence NIH
load, showed the highest incidence of stenosis (30%).
From the analytic point of view, the site of the lesion
comprises a crucial cornerstone for influencing the outcome of
endovascular salvage of dysfunctional AVFs. Such influence can
be explained by the difference in the etiopathology including
exposure to the mechanical factors, the strategic location of
the lesion in the circuit with the impact of the anatomical
surrounding structures, and the vulnerability of specific
segments for repetitive trauma.
To the best of our knowledge, there is limited evidence in the
literature concerning the patency rates according to different
lesion sites following endovascular salvage for dysfunctional
AVFs. The overall 1ry patency rates were 61% and 42% at 6
months and 12 months respectively in a study that evaluated
the outcomes and durability of PTA for 159 stenoses of AVFs, with or without stenting [24]. Another study had reported
early recurrence rate of 23.2% within 6 months in spite of high
technical (96.3%) and clinical success (97.2%) [25]. While
the clinical success, technical success, and 1ry patency rates
were 95.7%, 86.5%, and 71.9% respectively in another study
that evaluated the anatomical causes of maturation failure
and assessing clinical outcomes after the causative lesions of
immature AVF corrected by endovascular treatment [26].
In the current study, the 6 months 1ry patency rate after
endovascular salvage for dysfunctional AVFs due to arterial
lesions was 44.4-50% and those due to anastomotic lesions was
76.6%. Whereas the 6 months 1ry patency rates following PTA
for venous lesions were as follows: venous juxta-anastomotic
(88.8%), needling segment (74.1%), junctional (66.6%), and
(55.5%) after PTA and stenting for venous central lesions.
From the etiopathological point of view, NIH plays an integral
role in restenosis after PTA wherever the site of the lesion.
Additive pathology varies from atherosclerosis in the arterial
side, technical problem at the anastomotic site, and fibrosis &
residual thrombosis at the venous side.
In the current study, arterial lesions had a relatively high
success rate (85.7-90%), but on the contrary, they had the lowest
patency rate (44.4-50%); especially when multiple. This success
rate can be attributed to both the site of the lesion (being on the
high pressure side of the circuit) and its nature (being mostly
soft atherosclerotic plaque). On the other hand, the poor patency
rate was attributed to both progressions of atherosclerosis and/
or dissection during PTA with resultant NIH and thrombosis
thereafter. Hence, the relatively good immediate outcome should
be taken cautiously. In addition, it is recommended to minimize
the incidence of post PTA dissection by using just the optimum
balloon length required with minimal pressure (nominal) and
long inflation (at least 2 minutes) when dealing with arterial
lesions.
Among the different venous sites, juxta-anastomotic lesions
carry the best 6 month patency rate (88.8%) when compared
with other venous sites. This can be explained by the lack of
repetitive trauma which is peculiar to the needling segment (6
month patency rate is 74.1%), and the lack of compression by
the surrounding fascia which is met in junctional segment (6
month patency rate is 66.6%).
Targeting a better patency rate for both the
anastomotic
and juxta-anastomotic lesions, we do postulate that refinement
of the initial surgical technique could be of help to minimize
the stenosis from the start and restenosis after PTA. Whereas
in the needling segment, the puncture technique modulation
would definitely be of great help to optimize the patency after
PTA as this will affect the degree of restenosis and incidence of
intravenous synechia along the pathway of the needle punctures.
The challenge will be in the junctional lesions due to the impact of the
surrounding fascia that leads to recoil after successful PTA
minimizing the patency rate. And hence, the assisted surgical
role is evoked to relieve such compression.
Central venous lesions had the worst success rate together
with poor 6 month patency rates. This augments the major
prophylactic role of the “fistula first” principle avoiding
unnecessary HD central venous catheters insertion with their
subsequent central venous pathology. It was found in the current
study that tackling total central occlusions is much more difficult
than similar peripheral lesions. So, in symptomatic cases, early
intervention at the stenosis phase is better than delaying it
till total occlusion ensues. This is attributed to coexistence of
multiple factors responsible for total occlusion in one hand
(including severe fibrosis, and organized thrombosis), and the
presence of sizeable extensive collaterals in the other hand (that
direct the wire away from the main pathway). Accordingly, to
optimize the success rate, we have to optimize the access and
tools. And to improve the patency rate, we have to consider
venous stents, drug eluting technology, and proper surveillance.
The site of the lesion has an impact on the outcome of
endovascular salvage of dysfunctional AVF with variable
immediate success and later patency rates. Arterial and central
venous lesions have the least success and patency rates.
However, unfavorable rates are not an invitation to regret paying
effort for salvage. Simply, because intervention can be repeated,
and more importantly, the use of suitable tools and techniques
can optimize the results according to each lesion site.
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