Endovascular treatment of hemodialysis arteriovenous fistulas: is immediate post-interventional blood flow a predictor of patency

Predictors associated with early and late restenosis of arteriovenous fistulas and grafts after percutaneous transluminal angiography

BACKGROUND

The objective of this study was to assess postintervention patency and analyze the predictive factors associated with early and late restenosis after intervention in hemodialysis arteriovenous fistulas (AVF) and arteriovenous grafts (AVG).

METHODS

This study retrospectively analyzed 284 hemodialysis patients who underwent percutaneous transluminal angioplasty (PTA) due to AVF and AVG stenosis. A total of 350 PTA procedures were performed. Clinical, anatomical, biochemical, and technical variables were analyzed. Using univariate and multivariate analyses, we assessed the postintervention patency of PTA by follow-up, and identified the predictive factors taking into account competing risks.

RESULTS

Postintervention patency rates at 3, 6, 12, and 24 months were 86.5%, 66.4%, 42.6%, and 29.8%, respectively, with a median patency duration of 11±0.71 months. Kaplan-Meier analysis showed that the patency rate of the AVF group (n=271) was dramatically higher than the AVG group (n=79) at 3, 6, and 12 months after PTA, respectively (88.9% vs. 78.5%, 69.0% vs. 57.4%, 48.8% vs. 20.0%, P<0.01). Cox survival analysis revealed that the factors associated with postintervention patency of AVF included age of fistulas, serum albumin (ALB) levels, location of stenoses, lesion length longer than 2 cm, multiple stenoses, and maximal pressure of dilatation lower than 16 atm. In addition, factors related to postintervention patency of AVG included the presence of diabetes and hypertension, and serum ALB.

CONCLUSIONS

This study demonstrated that the risk factors associated with postintervention patency of AVF included age of fistulas, lower levels of serum ALB, location of stenoses, lesion length longer than 2 cm, multiple stenoses, and maximal pressure of dilatation lower than 16 atm. In addition, risk factors related to postintervention patency of AVG included the presence of diabetes and lower levels of serum ALB, while the presence of hypertension was found to be a protective factor for reducing patency loss of AVG. Among all these factors, serum ALB and multiple stenoses tended to predict early restenosis, while pressure of dilatation tended to predict late restenosis.

Analysis of factors for post–percutaneous transluminal angioplasty primary patency rate in hemodialysis vascular access

Background:

Although percutaneous transluminal angioplasty has been established as a first-line therapy for access failure in dialysis, there are few reports on primary patency after percutaneous transluminal angioplasty. We investigated factors associated with primary patency following the first percutaneous transluminal angioplasty performed after vascular access construction in patients with arteriovenous fistula, including blood flow volume before and after percutaneous transluminal angioplasty and previously reported factors.

Methods:

We used medical records at six dialysis centers to retrospectively identify and analyze prognostic factors for primary patency after percutaneous transluminal angioplasty in 159 patients with arteriovenous fistula who underwent initial percutaneous transluminal angioplasty after vascular access construction.

Results:

Multivariate analysis with the Cox proportional hazard model showed that primary patency after percutaneous transluminal angioplasty in patients with arteriovenous fistula was significantly associated with lesion length (hazard ratio, 1.76; 95% confidence interval, 1.01–3.07; P = 0.045), and blood flow volume after percutaneous transluminal angioplasty (hazard ratio, 0.71; 95% confidence interval, 0.60–0.84; P < 0.001). When blood flow volume after percutaneous transluminal angioplasty was classified into three categories, risks of outcome events defining the end of primary patency after percutaneous transluminal angioplasty were significantly lower for 400–630 mL/min (hazard ratio, 0.38; 95% confidence interval, 0.21–0.68; P = 0.001) and >630 mL/min (hazard ratio, 0.16; 95% confidence interval, 0.06–0.40; P < 0.001) compared with <400 mL/min.

Conclusion:

Our study showed that blood flow volume after percutaneous transluminal angioplasty is an important prognostic factor for primary patency after percutaneous transluminal angioplasty in patients with arteriovenous fistula.

Thrombosed native hemodialysis fistulas: Technical and clinical outcomes of endovascular recanalization and factors influencing patency

Purpose:

To evaluate the technical and clinical results of endovascular recanalization of thrombosed native hemodialysis fistula and the factors influencing patency.

Methods:

A retrospective study was conducted with 73 patients who had thrombosed arteriovenous fistulas and were treated with endovascular methods. Patient characteristics, arteriovenous fistula-related characteristics, and endovascular procedures were analyzed. Technical and clinical results and patency rates were evaluated. The factors influencing patency were analyzed using a univariate and multivariate Cox proportional hazards model.

Results:

Technical and clinical success rates were 93% (68/73) and 85% (62/73), respectively. At 3, 6, and 12 months, the primary patency rates were 87.9%, 73.3%, and 64.8%; assisted primary patency rates were 89.2%, 78.6%, and 70.7%; and secondary patency rates were 90.8%, 87.2%, and 83.1%, respectively. Previous intervention and cephalic arch stenosis were risk factors for lower primary and assisted primary patency ( p < 0.05 for all). Cephalic arch stenosis was the only risk factor for lower secondary patency ( p < 0.05). No major complications associated with the procedures were noticed.

Conclusion:

Endovascular treatment was effective for the immediate recanalization of thrombosed arteriovenous fistula. In addition, previous intervention and cephalic arch stenosis were significantly related to lower arteriovenous fistula patency.

Factors associated with outcome after successful radiological intervention in arteriovenous fistulas: A retrospective cohort

Introduction:

Arteriovenous fistulas are the best form of vascular access for haemodialysis. A radiological balloon angioplasty is the standard treatment for a clinically relevant stenosis, but the recurrence rate is high. Data on factors associated with recurrence are limited.

Methods:

A single centre, retrospective analysis was performed for 124 consecutive patients who had successful interventions for dysfunctional arteriovenous fistulae, to examine factors associated with post-intervention patency. Follow-up was at least 1 year for all patients. Variables associated with primary and cumulative patency were pre-specified and assessed using both un-adjusted (univariate) and adjusted Cox proportional hazards models. Analysis was repeated for a subgroup of 80 patients with a single lesion only in order to examine the potential effects of stenotic lesion characteristics on patency.

Results:

Factors found to have a significant association with poorer outcomes (less time to loss of patency) included thrombosis at the time of intervention and a history of previous intervention. Fistula age (log days) was significantly associated with better outcomes (greater time to loss of patency). Non-white ethnicity, lesion length, and patient age were also significantly associated with accelerated loss of patency.

Discussion:

The factors we have identified as linked to poor outcome may help to identify patients in whom a balloon angioplasty is unlikely to provide a durable outcome. This may prompt exploring alternative treatment or dialysis options at an early stage.

Predicting Technical Success after Fistuloplasty: An Analysis of 176 Procedures

BACKGROUND

Significant stenoses in arteriovenous fistulae (AVFs) or arteriovenous grafts (AVGs) with limitation of flow and dialysis inadequacy should prompt consideration for fistuloplasty. We sought to identify fistulae, lesions, and patient-specific variables, which predict for outcomes after fistuloplasty.

METHODS

Data were extracted retrospectively from a renal access database from 2011 to 2016 of patients undergoing fistuloplasty. Demographics, comorbidities, outcomes of intervention, and flow rates documented on preintervention and postintervention duplex were collected. Secondary analysis of factors associated with postfistuloplasty flow rates of >600 mL/min, previously shown to be predictive of not requiring future intervention, was performed.

RESULTS

Of 204 attempted fistuloplasties, 176 were completed. One hundred forty (79.5%) were native AVFs and 34 (19.3%), AVGs (no data for 2). Median stenosis treated was 75%, with a majority (43.8%) in the proximal outflow vein. Flow rate on duplex after fistuloplasty was significantly better in AVFs (mean improvement 189.2 mL/min) than that in AVGs (mean improvement 51.8 mL/min; P = 0.034). Greatest flow improvement occurred for needling site stenotic lesions compared with other locations (from anastomosis to central vein) but was not significant. Brachio-brachial or brachio-axillary AVGs did significantly (P < 0.05) worse than all other fistulae types. The presence of hypertension was predicted for postfistuloplasty flow rate of >600 mL/min.

CONCLUSIONS

Flow rates after fistuloplasty vary depending on the type of fistula treated and the presence of hypertension. Knowledge of this can lead to better patient selection and counseling for fistuloplasty.

Definitions and End Points for Interventional Studies for Arteriovenous Dialysis Access

This paper is part of the Clinical Trial Endpoints for Dialysis Vascular Access Project of the American Society of Nephrology Kidney Health Initiative. The purpose of this project is to promote research in vascular access by clarifying trial end points which would be best suited to inform decisions in those situations in which supportive clinical data are required. The focus of a portion of the project is directed toward arteriovenous access. There is a potential for interventional studies to be directed toward any of the events that may be associated with an arteriovenous access' evolution throughout its life cycle, which has been divided into five distinct phases. Each one of these has the potential for relatively unique problems. The first three of these correspond to three distinct stages of arteriovenous access development, each one of which has been characterized by objective direct and/or indirect criteria. These are characterized as: stage 1-patent arteriovenous access, stage 2-physiologically mature arteriovenous access, and stage 3-clinically functional arteriovenous access. Once the requirements of a stage 3-clinically functional arteriovenous access have been met, the fourth phase of its life cycle begins. This is the phase of sustained clinical use from which the arteriovenous access may move back and forth between it and the fifth phase, dysfunction. From this phase of its life cycle, the arteriovenous access requires a maintenance procedure to preserve or restore sustained clinical use. Using these definitions, clinical trial end points appropriate to the various phases that characterize the evolution of the arteriovenous access life cycle have been identified. It is anticipated that by using these definitions and potential end points, clinical trials can be designed that more closely correlate with the goals of the intervention and provide appropriate supportive data for clinical, regulatory, and coverage decisions.

Impact of Lesion Morphology on Durability After Angioplasty of Failed Arteriovenous Fistulas in Hemodialysis Patients

PURPOSE

To investigate if morphological patterns of arteriovenous fistula (AVF) venous lesions affect primary patency after percutaneous transluminal angioplasty (PTA).

METHODS

From July 2014 to June 2015, 262 patients underwent PTA for failed AVFs. A total of 104 patients were excluded owing to (1) calcification or AVF occlusion precluding ultrasound examination, (2) central venous or arterial lesions, and (3) no follow-up, leaving 158 patients (mean age 71±12; 96 men) for analysis. More than half of the patients had one or more previous PTAs for the failed AVF. Prior to PTA the stenotic lesions were assessed using ultrasonography to determine stenotic patterns at the minimum lumen area site and to evaluate the flow volume in the brachial artery. Three stenotic patterns were identified: intimal hyperplasia (IH) stenosis (n=110), shrinking lumen stenosis (n=32), and venous valve-related stenosis (n=16). The main outcome measure was primary patency after PTA estimated using Kaplan-Meier analysis. Predictors for loss of primary patency were determined using a multivariate Cox proportional hazards model; the results are presented as the adjusted hazard ratio (HR) and 95% confidence interval (CI).

RESULTS

Median follow-up after PTA was 6.3 months (interquartile range 3.3, 10.5). The 6-month primary patency estimates were 56%±5% in the IH group, 40±9% in the shrinking lumen group, and 100% in the valve stenosis group (IH vs shrinking, p=0.013; IH vs valve, p=0.003). In multivariate analysis, shrinking lumen morphology had a negative impact on primary patency (HR 2.05, 95% CI 1.25 to 3.36, p=0.005), while venous valve-related stenosis had a positive impact (HR 0.19, 95% CI 0.04 to 0.79, p=0.023). Flow volume (10-mL/min increments; HR 0.97, 95% CI 0.96 to 0.99, p=0.004) and history of PTA (HR 1.66, 95% CI 1.06 to 2.60, p=0.029) were also independently associated with primary patency after PTA.

CONCLUSION

The patterns of AVF stenosis as determined by ultrasound can affect the outcome of treatment with balloon dilation.

Endovascular Stent Placement for Hemodialysis Arteriovenous Access Stenosis

This study aims to report the outcomes of nitinol and polytetrafluoroethylene covered stent placement to treat hemodialysis arteriovenous access stenosis at a single center over a five-year period. Clinical and radiological information was reviewed retrospectively. Poststent primary and secondary patency rates were determined using Kaplan-Meier analysis. Ten clinical variables were subjected to multivariate Cox regression analysis to determine predictors of patency after stent placement. During the study period 60 stents were deployed in 45 patients, with a mean follow-up of 24.5 months. The clinical and anatomical success rate was 98.3% (59/60). Poststent primary patency rates at 6, 12, and 24 months were 64%, 46%, and 35%, respectively. Poststent secondary patency rates at 6, 12, and 24 months were 95%, 89%, and 85%, respectively. Stent placement for upper arm lesions and in access less than 12 months of age was associated with reduced primary patency (adjusted hazards ratio [HR] 5.1, p = 0.0084, and HR 3.5, p = 0.0029, resp.). Resistant or recurrent stenosis can be successfully treated by endovascular stent placement with durable long-term patency, although multiple procedures are often required. Stent placement for upper arm lesions and in arteriovenous access less than 12 months of age was associated with increased risk of patency loss.

Patterns of Blood Flow as a Predictor of Maturation of Arteriovenous Fistula for Haemodialysis

Purpose

A palpable “thrill” is traditionally associated with success following arteriovenous fistula (AVF) surgery. A thrill typically characterizes turbulent flow and this is a paradox as turbulence is a driver of neointimal hyperplasia. Spiral laminar flow (SLF) has been described as normal and protective pattern of flow in native arteries and is associated with superior patency in bypass grafts that generate it. The aim of this study was to define the pattern of flow within AVFs immediately post-operatively and at follow-up to assess maturation.

Methods

Doppler ultrasound was used immediately post-operatively and at follow-up (6 weeks). Blood flow was assessed as SLF or non-SLF. Two blinded qualified observers analysed the images. Patients were followed up for 6 months. Maturation was statistically analysed against the type of flow.

Results

Sequential patients having AVF surgery (n=56) were assessed: 46 (82%) patients had a thrill, 3 patients had no flow and 7 patients had pulsatile flow without a palpable thrill. SLF was present in 80% of those with a thrill but not in any without a thrill (p<0.0001). At follow-up (n=51) 41, patients had a matured AVF (80%), of which 76% had SLF immediately post-operatively. Only one patient with SLF failed to mature. In the non-SLF group 5 of the 15 AVFs failed to mature (66%; p<0.005).

Conclusions

SLF was strongly supportive of successful fistula maturation. A “thrill” was characteristic of spiral rather than turbulence. The mechanism of this apparent beneficial effect of this pattern of flow requires further investigation.

Predictors of patency after balloon angioplasty in hemodialysis fistulas: a systematic review

Percutaneous transluminal angioplasty (PTA) is an established treatment for dysfunctional hemodialysis fistulas. This article systematically reviews evidence for predictors of patency after PTA. Outcomes assessed were primary, assisted primary, and secondary patency after intervention, and findings were summarized descriptively. This review included 11 nonrandomized observational studies of 965 fistulas in 939 patients. Follow-up ranged from 0 days to 10 years. Study quality was overall suboptimal. Newer fistulas and longer lesion length may be associated with primary patency loss after PTA. Further studies are needed to confirm these findings, to identify potentially modifiable factors, and to guide the testing of new endovascular devices.

Arterio venous fistula experience at a tertiary care hospital in Pakistan

OBJECTIVE

To evaluate the two year patency rate of functioning arteriovenous fistula.

METHODOLOGY

This prospective case series study was conducted at Department of Urology, Jinnah Postgraduate Medical Centre, Karachi, from 1(st) January 2009 to 31(st) December, 2010. Patients were chosen for CBRC arteriovenous fistula at wrist and patients undergoing other types of vascular access or secondary fistula formation were excluded.

RESULTS

One hundred and eighty two patients underwent arteriovenous fistula formation. The mean ± SD age was 63 ± 13 years and there were 102 (56%) males and 80 (44%) females. 12.6% fistulae failed within first month without dialysis. The primary patency rate was 66.5% at three months and 57.7% at six months. Failing arteriovenous fistula was managed by new arteriovenous fistula in our series. 28.6% patients had redo arteriovenous fistula. This study demonstrated a poor outcome for fistulas in diabetic patients. Fifteen out of 23 (65.2%) who failed primarily were diabetics and out of these diabetics 13 (86.7%) failed in first three months. Infection and burst fistulae were found in nine (4.9%), pseudo aneurysm in 3.2%, fever 4.9%, peri-operative failure 0.55% and burst fistulae 3.2%.

CONCLUSIONS

One-third of radiocephalic fistulas fail within two years. The outcome is worse for women and diabetic patients. This information may be useful in assessing and counseling patients with end-stage renal failure. Arteriovenous fistula is the better and ideal choice for haemodialysis. A Radiocephalic fistula in forearm seems to have better results as comparison to cubital fossa arteriovenous fistula. End to side anastomosis results are better than side to side anastomosis.