A systematic review aggregated data and individual participant data meta-analysis of percutaneous endovascular arteriovenous fistula.

OBJECTIVE: To assess the short-term and mid-term safety and efficacy of percutaneous endovascular arteriovenous fistula (pAVF) creation. METHODS: A systematic search was implemented corresponding to the PRISMA 2020 and the PRISMA for individual participant data (IPD) systematic reviews 2015. Aggregated data from the included studies were obtained and meta-analyzed regarding both the overall pAVF efficacy and the comparison of pAVF with surgical AVF (sAVF). We performed a two-stage IPD meta-analysis for studies comparing pAVF and sAVF regarding primary and secondary patency. Primary end points included primary patency, secondary patency, and functional cannulation. RESULTS: Eighteen studies with 1863 patients were included. The overall pAVF, primary patency, secondary patency, functional cannulation and abandonment rates were 54.01% (95% confidence interval [CI], 40.69-66.79), 87.27% (95% CI, 81.53-91.42), 79.94% (95% CI, 65.94-89.13), and 15.58% (95% CI, 7.77-28.79), respectively. The overall pAVF, technical success, maturation, reintervention per person-years and mean time to maturation rates were 97.08% (95% CI, 95.66-98.04), 82.13% (95% CI, 71.64-89.32), 0.80 (95% CI, 0.34-1.47), and 58 days (95% CI, 36.64-92.82), respectively. Secondary patency and pAVF abandonment rates where the only end points were WavelinQ and Ellipsys displayed statistically significant differences of 81.36% (95% CI, 76.15-85.65) versus 92.12% (95% CI, 87.94-94.93) and 32.54% (95% CI, 22.23-44.87) versus 11.13% (95% CI, 4.82-23.65). An IPD meta-analysis of hazard ratios for primary and secondary patency between pAVF and sAVF were 1.27 (95% CI, 0.61-2.67) and 1.25 (95% CI, 0.87-1.80), favoring sAVF. Statistically significant difference between pAVF and sAVF were solely depicted for steal syndrome relative risk of 5.91 (95% CI, 1.12-31.12) and wound infections relative risk of 4.19 (95% CI, 1.04-16.88). Plotting of pAVF smoothed hazard estimate displayed an upsurge in the probability of primary patency failure at 1 month after the intervention. CONCLUSIONS: Although we failed to identify statistically significant differences between pAVF and sAVF regarding any of the primary end points, pAVF displayed a decreased risk for steal syndrome and wound infection. Although both the Ellipsys and WavelinQ devices displayed satisfactory secondary patency rates, Ellipsys demonstrated a statistically significant improved rate compared with WavelinQ. Additionally, and despite the borderline statistically insignificant inferior reintervention rate displayed by WavelinQ, one in three WavelinQ pAVFs resulted in abandonment. The introduction of pAVF as a treatment modality calls for standardized definition adjustment and improvement.

Impact of arteriovenous fistulas versus arteriovenous grafts on vascular access performance in haemodialysis patients: A systematic review and meta-analysis.

BACKGROUND: Controversy exists regarding the best-performing vascular access type for patients undergoing haemodialysis. We aimed to compare outcomes of starting dialysis on arteriovenous fistulas (AVFs) versus arteriovenous grafts (AVGs) in haemodialysis patients. METHODS: We conducted a systematic search of multiple electronic information sources and bibliographic reference lists. The following outcome parameters were evaluated at 1, 2 and 5 years: primary failure, defined as access never used for dialysis; primary patency, defined as intervention-free access survival; primary-assisted patency, defined as uninterrupted access survival with interventions; and secondary patency, defined as cumulative access survival. RESULTS: We identified 15 comparative studies reporting a total of 118,434 patients who initiated haemodialysis with AVF (n = 95,143) or AVG (n = 23,291). Our analysis demonstrated that AVF was associated with significantly higher primary failure rate (OR: 2.05, p = .0005) but significantly higher rate of primary patency at 1 year (OR: 1.91, p < .00001), at 2 years (OR: 2.52, p < .00001) and at 5 years (OR: 2.59, p < .00001); and primary-assisted patency at 1 year (OR: 1.71, p < .00001), at 2 years (OR: 2.13, p < .00001) and 5 years (OR: 2.79, p < .00001). There was no significant difference in secondary patency at 1 year (OR: 1.08, p < .00001) but AVF had better secondary patency at 2 years (OR: 1.26, p < .00001) and 5 years (OR: 1.60, p < .00001) than AVG. CONCLUSIONS: The meta-analysis of best available comparative evidence (Level 2) demonstrated that AVFs may be associated with significantly higher primary failure rate but higher primary patency, primary-assisted patency and secondary patency at 1, 2 and 5 years compared to AVGs. However, the available evidence is subject to significant selection bias and confounding by indication.

Outcomes of the Weighted Peritoneal Dialysis Catheter in Patients at Risk of Percutaneous Catheter Failure.

BACKGROUND: The weighted catheter has shown promising results in retrospective and randomized studies. We examined its usefulness in patients with previous failed non-weighted peritoneal dialysis (PD) catheters or previous abdominal surgery. METHODS: The insertion, start, end, and removal dates were recorded for all-type catheter insertions from 2011 to 2016. Primary and secondary failure rates were recorded, defined as failure to ever establish flow (primary) or failure after a period of successful PD (secondary). Patients were censored from analysis if PD ended due to death, transfer of care, transfer to hemodialysis, transplantation, or if the patient recovered renal function. RESULTS: There were 44 weighted, 75 non-weighted open surgical, and 143 percutaneous catheters. There was previous abdominal surgery in 29% and 6% of patients receiving surgically inserted and percutaneous catheters, respectively (p < 0.0001). Primary failure rates were 4/44 (9%), 20/75 (27%), and 26/143 (18%) in weighted, non-weighted surgical, and percutaneous catheters, respectively. There were reduced primary and secondary failure rates in the weighted (9% primary and 15% secondary) versus non-weighted surgically inserted group (27% primary and 46% secondary) (p = 0.04). There was no difference between primary (p = 0.15) and secondary (p = 0.5) failure rates between weighted and percutaneously inserted catheters. Kaplan-Meier survival analysis revealed overall increased catheter survival in the weighted group (p = 0.02). CONCLUSION: Weighted catheters were associated with increased survival and decreased failure rates compared with non-weighted surgical catheters, despite usage in patients at higher risk of catheter failure due to previous failed catheters and abdominal surgery.

Diameter Criteria Have Limited Value for Prediction of Functional Dialysis Use of Arteriovenous Fistulas.

OBJECTIVE: To determine the value of diameter measurements for prediction of functional dialysis use (FDU) of arteriovenous fistulas (AVF). METHODS: Review of access operations and dialysis databases from January 1, 2007 to August 1, 2015. Follow up until July 1, 2016. FDU defined as six consecutive dialysis sessions with two needles on the AVF. Artery and vein diameters measured by portable ultrasound in access clinic. Contribution of diameter to predict FDU assessed with logistic regression. Diagnostic accuracy assessed by sensitivity, specificity, positive and negative predictive values (PPV and NPV). RESULTS: 803 AVF operations were analysed: 507 (63%) radiocephalic fistulas (RCAVF), 237 (30%) brachiocephalic fistulas (BCAVF), and 59 (7%) brachiobasilic fistulas (BBAVF). Women had lower FDU in RCAVF (0.65, 95% CI 0.58-0.72 vs. 0.86, 95% CI 0.81-0.89; p < .0001), but not in BCAVF (0.83, 95% CI 0.75-0.89 vs. 0.81, 95% CI 0.73-0.88; p = .75). Female gender was an independent negative predictor of FDU in RCAVF (OR 0.31; 95% CI 0.20-0.49). Vascular kidney disease was an independent negative predictor for FDU in RCAVF (OR 0.33; 95% CI 0.17-0.64) and BCAVF (OR 0.22; 95% CI 0.09-0.57) in multivariable analysis. Artery and vein diameter did not improve the model for RCAVF. Vein diameter as categorical variable improved the model for BCAVF. Diameter cut off of radial artery ≥ 2 mm has 96% sensitivity, 86% PPV, 9% specificity, and 29% NPV in men. Radial artery diameter ≥2 mm had 96% sensitivity, 67% PPV but 13% specificity and 62% NPV in women. CONCLUSIONS: Diameter is a poor predictor of FDU of AVF. Arterial diameter measurements add no diagnostic value for BCAVF. Poor specificity suggests a diameter under 2 mm at the wrist should not preclude AVF formation. Vascular kidney disease is an independent negative predictor for FDU in all AVF.

Comparison of surgical and radiological interventions for thrombosed arteriovenous access.

INTRODUCTION:: To compare open surgical and radiological interventions for thrombosed arteriovenous access for dialysis. METHODS:: A retrospective analysis of access procedures and dialysis episodes from 1 December 2002 to 30 November 2015 with follow-up up to 1 August 2016. Hospital records and dialysis database interrogated for further interventions and length of functional use. RESULTS:: Some 128 surgical and 27 radiological thrombectomies were compared. Radiological treatment was successful in 24 (89%) cases and surgical interventions in 65 cases (51%; p < 0.001). In all, 82 (64%) of the 128 surgical thrombectomies had no additional treatment, 43 (34%) had a surgical revision and 3 cases (2%) had an on-table balloon angioplasty. All 27 interventional thrombectomies had an additional balloon angioplasty. Success rate was significantly increased after a surgical revision (74%) or balloon angioplasty (87%) compared to no adjuvant procedure (38%; p < 0.001). There was a trend towards higher primary failure rates of arteriovenous fistula thrombectomies in the upper arm (57%) compared to the arteriovenous fistula thrombectomies in forearm (40%) and arteriovenous graft thrombectomies (33%; p = 0.056). Assisted primary patency was better after interventional treatment compared to surgery (p = 0.02) and significantly better after thrombectomy with additional treatment (p = 0.005). Patency after surgical revision or balloon angioplasty of the access was similar (p = 0.15). More procedures were required to maintain the access after balloon angioplasty than after surgical revision, and intervention-free survival was better after surgical revision (p = 0.02). CONCLUSION:: Revision procedures significantly increase success rate of access thrombectomies. Radiological thrombectomies have higher success rates but lower intervention-free survival and need more additional procedures to maintain patency.

Effect of first cannulation time and dialysis machine blood flows on survival of arteriovenous fistulas.

Background: To study the effect of cannulation time on arteriovenous fistula (AVF) survival. Methods. Analysis of two prospective databases of access operations and dialysis sessions from 12 January 2002 through 4 January 2015 with follow-up until 4 January 2016. First cannulation time (FCT), defined from operation to first cannulation, was categorized as <2 weeks, 2-4 weeks, 4-8 weeks, 8-16 weeks and ≥16 weeks. Early cannulation was defined as FCT within 4 weeks. AVF survival was defined as the date until the AVF was abandoned. Maximum machine blood flow rate (BFR) for the first 29 dialysis sessions on AVF was analysed. Results: Altogether, 1167 AVF with functional dialysis use were analysed: 667 (57%) radial cephalic AVF, 383 (33%) brachiocephalic AVF and 117 (10%) brachiobasilic AVF. The 631 (54%) AVF created in on-dialysis patients were analysed separately from 536 (46%) AVF created in pre-dialysis patients. AVF survival was similar between cannulation categories for both pre-dialysis patients (P = 0.19) and on-dialysis patients (P = 0.83). Early cannulation was associated with similar AVF survival in both pre-dialysis patients (P = 0.82) and on-dialysis patients (P = 0.17). Six consecutive successful cannulations from the start were associated with improved AVF survival (P = 0.0002). A below-median BFR at the start of dialysis was associated with better AVF survival (P < 0.0001). A below-median increase in BFR in the first 2 months was associated with worse AVF survival (P = 0.007). The type of AVF, diabetes, pre-dialysis state at operation and six successful cannulations from the start were independent predictors for AVF survival. Conclusions: FCT is not associated with AVF survival. Failures to achieve six successful cannulations from the start of dialysis and higher machine BFR in the first week of dialysis are associated with decreased AVF survival.

Effect of ethnicity and socioeconomic status on vascular access provision and performance in an urban NHS hospital.

BACKGROUND: The aim of this study was to examine the effect of ethnicity, socioeconomic group (SEG) and comorbidities on provision of vascular access for haemodialysis (HD). METHODS: This was a retrospective review of two databases of HD sessions and access operations from 2003-11. Access modality of first HD session and details of transplanted patients were derived from the renal database. Follow-up was until 1 January 2015. Primary failure (PF) was defined as an arteriovenous fistula (AVF) used for fewer than six consecutive dialysis sessions. AVF survival was defined as being until the date the AVF was abandoned. Ethnicity was coded from hospital records. SEG was calculated from postcodes and 2011 census data from the Office of National Statistics. Comorbidities were calculated with the Charlson Comorbidity Index. RESULTS: Five hundred incident patients started chronic HD in the study period. Mode of starting HD was not associated with ethnicity (P = 0.27) or SEG (P = 0.45). Patients from ethnic minorities were younger when starting dialysis (P < 0.0001). Some 928 AVF patients' first AVF operations were analysed: 68% Caucasian, 26% Asian and 6% Afro-Caribbean. Half were in the most deprived SEG and 11% in the least deprived SEG. PF did not differ by ethnicity (P = 0.29), SEG (P = 0.75) or comorbidities (P = 0.54). AVF survival was not different according to ethnicity (P = 0.13) or SEG (P = 0.87). AVF survival was better for patients with a low comorbidity score (P = 0.04). The distribution of transplant recipients by ethnic group and SEG was similar to the distributions of all HD starters. CONCLUSION: Ethnicity and socioeconomic group had no effect on mode of starting HD, primary AVF failure rate or AVF survival. Ethnic minorities were younger at start of dialysis and at their first AVF operation.

Is early cannulation of an arteriovenous fistula associated with early failure of the fistula?

OBJECTIVE: To study the effect of early cannulation of arteriovenous fistulas (AVF) on early AVF failure. METHODS: Analysis of two databases of access operations and dialysis sessions from 1/12/2002 till 1/4/2015. Follow-up until 1/4/2016. Functional dialysis use defined as six consecutive cannulations of the AVF with two needles. Early cannulation defined as needling of the AVF within 30 days of creation. Early failure was defined as abandonment for new form of access within 90 days of first cannulation. Machine blood-flow rates (BFR) of each dialysis session for the first 2 months collected from the dialysis database. RESULTS: We analysed 1167 AVFs with functional dialysis use. Some 148 AVFs (11%) were needled within 30 days. Early needling was not associated with increased early failure rates (p = 0.43). Early failure rates were lower in AVFs with six consecutive successful cannulations from the start (p = 0.002). There was a trend of reduced early failure rates (test for trend: p = 0.018) in the latter years of the study period, but no trend in early cannulation rates (p = 0.19). Failure to achieve six successful cannulations from the start was an independent predictor of early AVF failure but early needling was not an independent predictor in multivariate analysis. Average starting BFRs were higher in AVF that were needled early. CONCLUSIONS: Early cannulation was not associated with early failure. Failure to achieve six successful cannulations from the start was an independent predictor of early failure. The trend in yearly variation of early failure rates suggests that evolving practices influenced early failure rates.

Access ligation in transplant patients.

Access surgeons will encounter patients with functioning transplants who want to lose their fistula, and every dialysis unit sees patients returning after a failed kidney transplant for whom an old fistula is a readily available lifeline. The decision is straightforward in patients with perfectly functioning transplants and disabling complications of their fistula, or in patients with failing transplants and a good fistula. The challenge is to make this decision in patients with good transplant function and an asymptomatic fistula. Despite improvements in one-year survival of renal grafts, the long-term graft survival has improved modestly. This means about half of the patients with a successful kidney transplant will return to dialysis within 10 years. Use of recently developed risk calculators, based on clinical parameters, may help in the decision process. A high flow fistula can lead to heart failure but most fistulae are well tolerated in asymptomatic patients and the effects of closure of the AVF on the heart are modest. Recent evidence suggests that there may be benefits of a functioning AVF that may need to be considered in this decision process. This article reviews the literature and comes to pragmatic recommendations of what to do with this conundrum.

Should patients be on antithrombotic medication for their first arteriovenous fistulae?

PURPOSE: Evidence on the effect of antithrombotic medication on reducing early and late fistula failure is inconclusive. Antithrombotic use carries risks in patients with end-stage renal failure and could increase the risk of needling complications as a result of bleeding. The objectives of this study are to determine the effect of antithrombotic agents on early and late fistula failure and on the risk of interrupted start of cannulation of the fistula. METHODS: Retrospective analysis of two prospectively maintained databases of access operations and dialysis sessions of 671 patients who had their first fistula between 2004 and 2011. Early failure was defined as failure to reach six consecutive dialysis sessions at any time with two needles on the index form of access. Fistula survival was defined as the time from when the fistula was first used to fistula abandonment. RESULTS: Primary failure was similar between patients on antiplatelet (18.8%), anticoagulants (18.4%) or no antithrombotic medication (18.8%; p = 0.998). Antithrombotic medication did not have an effect on AVF survival (p = 0.86). Antithrombotic medication did not increase complicated cannulation rates, defined as the percentage of patients failing to achieve six uninterrupted dialysis sessions from the start (p = 0.929). CONCLUSIONS: Antithrombotic medication had no significant effect on primary failure rate, long-term fistula survival or initial complicated cannulation rates in our study. This suggests that patients already on antithrombotic medication can continue taking them without increasing the risk of interrupted dialysis.

UK organisation of access care.

National UK audits show that 73% of patients start renal replacement therapy (RRT) with haemodialysis (HD). However, 59% of those start HD on non-permanent access in the form of a tunnelled line (TL) or a non-tunnelled line (NTL), 40% on an arteriovenous fistula (AVF) and 1% on an arteriovenous graft (AVG). After 3 months, the number of patients dialysing on AVF was only 41%. Late referrals, within 90 days of starting dialysis to the renal service, occur in one-fifth of all incident HD patients. Referral to a surgeon was an important determinant of mode of access at first dialysis. However, referral to a surgeon occurred in 67% of patients who were known to the nephrologist for over a year and in 46% of patients who were known to nephrology less than a year but more than 90 days. Best practice tariffs of the National Health Service (NHS) payment by results program have set a target of 75% of prevalent HD occurring via an AVF or AVG in 2011/2012, rising to 85% in 2013/2014. We suggest that this target is best achieved by increasing timely referral to a surgeon for creation of access before HD is needed.

Elbow arteriovenous fistulae.

Multiple superficial veins in different anatomical configurations exist in the elbow. The resulting variety of elbow arteriovenous fistulae (AVFs) is described in this paper. A classification of elbow AVF in nontransposed AVF, transposed AVF and multiple outflow AVF is proposed. The nontransposed brachiocephalic AVF has the lowest primary failure rate and a good medium-term survival particularly in the elderly. The simplest technique is an end-to-side anastomosis of the median cubital vein to the brachial artery. In cases of small upper arm veins, a perforating vein AVF, using multiple outflow tracts, may be helpful to lower primary failure risk. In the era of vein mapping with portable ultrasound elbow AVF should be made when forearm veins are exhausted or too small. A side-to-side AVF in order to enhance retrograde flow in the median forearm vein seems rarely indicated, in particular considering the greater risk of steal and venous hypertension. A transposed brachiobasilic AVF is a tertiary access procedure after the simpler alternatives have been exhausted. There is conflicting evidence of the benefits of one-stage versus two-stage procedures. Therefore, the type of operation should be tailored to the individual patient.

Lower limb access.

Lower limb vascular access is used as an access site in patients in whom all upper limb possibilities for arteriovenous access creation are exhausted or with bilateral upper limb central vein occlusions. Autologous arteriovenous fistulae (AVF) using the greater saphenous vein have disappointing results apart from the isolated success. Autologous AVF using the femoral vein transposition have good results both in terms of long-term patency and are associated with a 10-fold reduction in infection risk compared with arteriovenous grafts (AVGs). However, a femoral vein transposition is a major undertaking and is associated with an increased risk of ischaemic complications. It is not a good option for patients with established peripheral arterial disease, but may be a good alternative for the younger patient with a high infection risk. The type of lower-extremity vascular access should be carefully tailored to the individual patient.

Accuracy of early postoperative clinical and ultrasound examination of arteriovenous fistulae to predict dialysis use.

AIM: The aim of this article is to assess the accuracy of early clinical and ultrasound (US) examination in terms of predicting arteriovenous fistula (AVF) dialysis use. METHODS: Physical and US examination of patent AVF was performed 4 weeks after fistula creation. AVF dialysis use was defined as subsequent use of an AVF for at least six consecutive dialysis sessions with two needles and a blood flow of more than 200 mL/min. RESULTS: Of 119 AVF patent at 4 weeks, 26 (22%) failed. Clinical examination was 96% sensitive for predicting successful dialysis, but only 21% specific for failure. Vein diameter above 5 mm and an arterial end-diastolic velocity above 110 cm/s were the best US predictors for dialysis use. Vein diameter was slightly better than arterial velocity in terms of predicting maturity (sensitivity: 83% vs 67%, specificity: 68% vs 65%). All assessments predicted AVF maturity (positive predictive value: clinical = 81%, US diameter = 90%, US velocity = 87%) much better than AVF failure (negative predictive value: clinical = 63%, US diameter = 53%, US velocity = 37%). CONCLUSION: One month after surgery, a new AVF with a thrill or a vein diameter >5 mm is likely to be used for dialysis. An AVF not meeting these criteria has an increased risk of failure and further investigations may be required.

Routine preoperative vascular ultrasound improves patency and use of arteriovenous fistulas for hemodialysis: a randomized trial.

BACKGROUND AND OBJECTIVES: Arteriovenous fistulas (AVFs) are the preferred vascular access for hemodialysis but have a considerable failure rate. This study investigated whether routine preoperative vascular ultrasound results in better AVF outcome than physical examination. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Patients with end-stage kidney disease referred for permanent access formation were assessed by independent examiners using physical examination and ultrasound. After random allocation, the ultrasound report was disclosed to the surgeon for patients in the ultrasound group but not for the clinical group. End points were AVF failure and survival rates, analyzed by intention to treat and by use for hemodialysis. RESULTS: AVFs were made in 208 of 218 randomized patients. Clinical and ultrasound groups were similar in terms of patient characteristics, allocation to individual surgeons, and proportion of forearm AVFs. The ultrasound group had a significantly lower rate of immediate failure (4% versus 11%, P = 0.028) and, among failed AVFs, less thrombosis (38% versus 67%, P = 0.029). Primary AVF survival at 1 year was not statistically different (ultrasound = 65%, clinical = 56%, P = 0.081). Assisted primary AVF survival at 1 year was significantly better for the ultrasound group (80% versus 65%, P = 0.012). The number of patients requiring preoperative ultrasound to prevent one AVF failure was 12. CONCLUSIONS: Routine preoperative vascular ultrasound in addition to clinical assessment improves AVF outcomes in terms of patency and use for dialysis. National Research Register, United Kingdom, trial number N0046131432.