Anastomotic Strategies to Improve Hemodialysis Access Patency—A Review

A review of technical steps in the performance of arteriovenous fistula creation

Although it is accepted that a functional arteriovenous fistula (AVF) is the optimal vascular access for dialysis, achieving function is difficult as the outcomes of AVF creation are sub-optimal. Many technical steps have been proposed to improve outcomes, but the strength of evidence to support these is unclear. Thus, a systematic review of all randomised controlled trials (RCT) of operative strategies to optimise AVF outcomes was performed to summarise the evidence, review the overall level of standardisation in RCT and thus determine if there was an objective basis for the technical steps in AVF creation. A systematic review of all RCT was performed and studies categorised by intervention type. The rationale for each intervention, outcomes and limitations were described. Most importantly, the completeness of reporting procedural steps was compared for all RCT and the therapeutic impact considered by AVF site. Of 6741 records meeting the search criteria, 31 RCT were included. Most RCT did not control for all technical aspects or fully detail the operative methods, with a mean of 4 technical steps not reported for which other RCT have been performed. Of studies involving a surgical intervention in RCF, 10/13 reported a significant benefit compared to only 5/15 studies in BCF or larger vessels. Overall, the adequacy of reporting the technical details in all RCT of technical steps in AVF creation was poor. Despite this, there was a consistent patency benefit found in RCT performed in smaller vessels although the extent of interaction between these is uncertain. There remain gaps in the literature in defining the optimal steps in fistula creation that, if confirmed, could significantly improve AVF outcomes. This makes it essential that future studies of novel techniques, such as percutaneous AVF creation, incorporate a standardised operating procedure of optimal current practice of surgically created AVF as a meaningful comparator.

Anchor versus parachute suturing technique in arteriovenous fistula creation for hemodialysis

INTRODUCTION

Chronic kidney disease (CKD) affects 13% of the global population and requires renal replacement therapy due to ESRD. Hemodialysis (HD) is the most common dialysis modality for ESRD patients, but establishing vascular access is challenging due to high morbidity and mortality rates. Arteriovenous fistulas (AVFs) are the gold standard for vascular access, but many fail due to anastomotic hemodynamics, vein diameter, and anastomatic suture technique. A prospective study was conducted to evaluate the impact of two continuous suturing techniques, the anchor technique and the parachute technique, on AVFs' initial outcomes.

METHODS

This randomized, controlled study involved adult patients who presented for AVF creation at our center. We divided the patients into two groups: anchors and parachutes. Four skilled vascular access surgeons performed the procedures. The primary goal was functional maturation of the AVF, defined as an AVF fistula ready to be cannulated with a cannulating vein length of at least 10 cm, a diameter of more than 6 mm, a depth of less than 6 mm, and a flow rate of 600 mL/min. Secondary goals included patency and complications such as bleeding, infection, steal syndrome, and aneurysmal dilatation at the anastomosis site. AVFs were evaluated immediately after surgery and during follow-up visits at the outpatient clinic. A duplex scan was performed to measure flow at various intervals. All patients provided appropriate written consent.

RESULT

The study involved 186 patients, with 86 excluded. 100 were randomized, with 5 cases losing follow-up and 3 deaths within 12 months. The follow-up continued until January 2024, with a mean of 8.6 months. The Parachute technique shows higher technical success (p value = 0.046) and primary patency at 30 days (p value = 0.014) compared to Anchor, but there is no statistical significance between both groups regarding functional maturation at 6 weeks (p value = 0.352). The parachute technique has a higher hematoma rate than the anchor technique (p value = 0.025), while other complications like intra-operative bleeding, postoperative bleeding, pseudoaneurysm formation, thrombosis, steal syndrome, and seroma formation show no significant differences. Nine patients, five of whom were diabetic and underwent conservative management, exhibited mild to moderate steal syndrome. This suggests an increased risk of steal syndrome among diabetic patients.

CONCLUSION

The parachute technique for AVF creation offers better technical success and short-term primary patency outcomes, while both parachute and anchor techniques are equally effective for long-term functional maturation and overall complication rates.

A Comparative Study of Continuous Versus Interrupted Suturing Technique in Creating a Vascular Access for Hemodialysis: An Institutional-Based Experience

Background Arteriovenous fistulas (AVFs) are considered the first and best access for patients with end-stage renal disease who need permanent vascular access for hemodialysis over arteriovenous grafts and central venous catheters for reasons that have been well-established. Poor early patency rates pose the biggest challenge in creating vascular access as they cause increased morbidity and economic/psychological concerns among patients. To minimize such effects, it is critical to use a patient-centered approach and carefully choose patients for AVF access creation. This study aimed to compare the primary patency of distal vascular access provided by continuous suturing versus that provided by interrupted suturing. Methodology This prospective study was conducted in the urology department of a superspecialty, tertiary care center from November 2021 to November 2022. Patency was assessed immediately after surgery (on the table), one month later, and six months later by palpating thrill and auscultating bruit. A total of 50 patients between the ages of 18 and 70 years who met the inclusion criteria were randomly assigned to two groups of 25 each. Results The baseline characteristics of both groups were comparable. At six months (p = 0.09), the continuous suturing group was observed to be somewhat better than the interrupted suturing group, with no significant difference in immediate and one-month patency rates. When compared to the continuous suturing group, the primary patency failure rate was significantly higher in the interrupted suturing group. Conclusions Thus, under appropriate circumstances, continuous sutures can be performed with greater ease, resulting in anastomosis that is as patent as that performed with interrupted sutures.

Efficacy of Regional Anesthesia in Secondary Procedures or Revisions of Arteriovenous Fistula

BACKGROUND

Several factors affect the outcomes of arteriovenous fistula (AVF) and end-stage renal disease (ESRD). This study aimed to evaluate the efficacy of regional anesthesia in secondary procedures or revisions of AVF.

METHODS

Medical records of patients who underwent treatment for AVF secondary procedures or revisions under brachial plexus block (BPB) between March 2016 and June 2019 were retrospectively analyzed. Patient characteristics and clinical outcomes were evaluated.

RESULTS

In total, 375 patients (mean age 65.6 ± 12.74; males 210, 56.0%) were enrolled in the study and 770 procedures were performed under BPB for AVF secondary procedures or revisions. The procedures included endovascular treatment (385, 50.0%), surgical treatment (105, 13.6%), and hybrid treatment (280, 36.4%). In 180 procedures (23.4%) for AVF lesions, the operative field included a single segment of the arm, whereas in 590 procedures (76.6%), the operative field included multiple segments. In total, 37 (4.8%) cases of 30-day postoperative complications were observed, of which 33 (4.3%) were surgery-related complications, 2 (0.3%) were BPB-related complications (neurapraxia), and 2 (0.3%) were contrast agent allergic reactions; 34 (4.4%) reinterventions of the total 201 (26.1%) reinterventions were performed within 30 days postoperatively. The mean operation time was 87.5 ± 55.35 min. The pain score for all patients was 0 (no pain), and no patient demanded opioids postoperatively.

CONCLUSIONS

Ultrasound-guided BPB is safe and effective for AVF secondary procedures or revisions in ESRD patients.

Outcomes of Percutaneous Portal Vein Intervention in a Single UK Paediatric Liver Transplantation Programme

Introduction

Percutaneous transluminal angioplasty (PTA), with or without stent placement, has become the treatment of choice for portal vein complications (PVC) following liver transplantation. We aimed to assess long-term outcomes of intervention in paediatric transplant recipients, in a single institution.

Materials and Methods

227 children received 255 transplants between November 2000 and September 2016. 30 patients developed PVC of whom 21 had percutaneous intervention. Retrospective clinical and procedural outcome data on these 21 patients were collected.

Results

21 patients, with median age 1.7 years (range 0.4–16.2), underwent 42 procedures with PTA with or without stenting. 36 procedures were for PV stenosis and 6 for PV thrombosis. Treatment was with primary PTA, with stenting reserved for suboptimal PTA result or restenosis within 3 months. 28 procedures were performed with PTA and 13 with stenting. Technical success (>50% reduction in mean pressure gradient, absolute pressure gradient ≤4 mmHg or venographic stenosis <30%) was achieved in 41 procedures. Failure to recanalise a thrombosed PV occurred in 1 procedure. There were no major procedural complications. Patients were followed-up with serial Doppler ultrasound surveillance. Kaplan–Meier estimated median primary patency was 9.9 months, with primary-assisted patency of 95% after median follow-up of 45.5 months (range 11.1–171.6).

Conclusion

With regular surveillance, excellent patency rates can be achieved following percutaneous intervention for PVC post-paediatric liver transplantation.

Regional versus local anesthesia for arteriovenous fistula creation in end-stage renal disease: a systematic review and meta-analysis

There is a consensus in the literature that regional anesthesia (RA) improves local hemodynamic parameters in comparison to local anesthesia (LA) during arteriovenous fistula (AVF) surgical construction. However, the effects of both techniques on fistula patency and failure rates are still controversial. The aim of this meta-analysis is to synthesize evidence from published randomized trials and observational studies regarding the safety and efficacy of RA versus LA in AVF surgical construction. A computer literature search of PubMed, Scopus, Web of Science, and Cochrane Central retrieved six randomized trials (462 patients) and one retrospective study (408 patients). Pooling data using RevMan software (version 5.3) showed that RA was superior to LA in terms of primary fistula patency rate (RR = 1.22, 95% CI [1.08, 1.37], p = 0.0010); however, both types were comparable in terms of primary fistula failure rate (RR = 0.81, 95% CI [0.47, 1.40], p = 0.46). In comparison to LA, RA was associated with improved hemodynamic parameters including fistula blood flow (MD = 25.08, 95% CI [19.40, 30.76], p<0.00001), brachial artery diameter (SMD = 2.63, 95% CI [2.17, 3.08], p<0.00001), and outflow venous diameter (SMD = 0.93, 95% CI [0.30, 1.75], p = 0.004). Postoperative complications were comparable between both groups (OR = 0.23, 95% CI [0.05, 0.97], p = 0.05). In conclusion, RA was associated with higher primary patency rates of AVF and improved local blood flow in comparison to LA; however, both procedures were comparable in terms of primary failure rates and postoperative complications. Larger well-designed trials with longer follow-up periods should compare both techniques in terms of long-term patency rates and safety outcomes.

Effect of regional versus local anaesthesia on outcome after arteriovenous fistula creation: a randomised controlled trial

BACKGROUND

Arteriovenous fistulae are the optimum form of vascular access in end-stage renal failure. However, they have a high early failure rate. Regional compared with local anaesthesia results in greater vasodilatation and increases short-term blood flow. This study investigated whether regional compared with local anaesthesia improved medium-term arteriovenous fistula patency.

METHODS

This observer-blinded, randomised controlled trial was done at three university hospitals in Glasgow, UK. Adults undergoing primary radiocephalic or brachiocephalic arteriovenous fistula creation were randomly assigned (1:1; in blocks of eight) using a computer-generated allocation system to receive either local anaesthesia (0·5% L-bupivacaine and 1% lidocaine injected subcutaneously) or regional (brachial plexus block [BPB]) anaesthesia (0·5% L-bupivacaine and 1·5% lidocaine with epinephrine). Patients were excluded if they were coagulopathic, had no suitable vessels, or had a previous failed ipsilateral fistula. The primary endpoint was arteriovenous fistula patency at 3 months. We analysed the data on an intention-to-treat basis. This study was registered with ClinicalTrials.gov (NCT01706354) and is complete.

FINDINGS

Between Feb 6, 2013, and Dec 4, 2015, 163 patients were assessed for eligibility and 126 patients were randomly assigned to local anaesthesia (n=63) or BPB (n=63). All patients completed follow-up on an intention-to-treat basis. Primary patency at 3 months was higher in the BPB group than the local anaesthesia group (53 [84%] of 63 patients vs 39 [62%] of 63; odds ratio [OR] 3·3 [95% CI 1·4-7·6], p=0·005) and was greater in radiocephalic fistulae (20 [77%] of 26 patients vs 12 [48%] of 25; OR 3·6 [1·4-3·6], p=0·03). There were no significant adverse events related to the procedure.

INTERPRETATION

Compared with local anaesthesia, BPB significantly improved 3 month primary patency rates for arteriovenous fistulae.

FUNDING

Regional Anaesthesia UK, Darlinda's Charity for Renal Research.

Effects of disturbed flow on vascular endothelium: pathophysiological basis and clinical perspectives

Vascular endothelial cells (ECs) are exposed to hemodynamic forces, which modulate EC functions and vascular biology/pathobiology in health and disease. The flow patterns and hemodynamic forces are not uniform in the vascular system. In straight parts of the arterial tree, blood flow is generally laminar and wall shear stress is high and directed; in branches and curvatures, blood flow is disturbed with nonuniform and irregular distribution of low wall shear stress. Sustained laminar flow with high shear stress upregulates expressions of EC genes and proteins that are protective against atherosclerosis, whereas disturbed flow with associated reciprocating, low shear stress generally upregulates the EC genes and proteins that promote atherogenesis. These findings have led to the concept that the disturbed flow pattern in branch points and curvatures causes the preferential localization of atherosclerotic lesions. Disturbed flow also results in postsurgical neointimal hyperplasia and contributes to pathophysiology of clinical conditions such as in-stent restenosis, vein bypass graft failure, and transplant vasculopathy, as well as aortic valve calcification. In the venous system, disturbed flow resulting from reflux, outflow obstruction, and/or stasis leads to venous inflammation and thrombosis, and hence the development of chronic venous diseases. Understanding of the effects of disturbed flow on ECs can provide mechanistic insights into the role of complex flow patterns in pathogenesis of vascular diseases and can help to elucidate the phenotypic and functional differences between quiescent (nonatherogenic/nonthrombogenic) and activated (atherogenic/thrombogenic) ECs. This review summarizes the current knowledge on the role of disturbed flow in EC physiology and pathophysiology, as well as its clinical implications. Such information can contribute to our understanding of the etiology of lesion development in vascular niches with disturbed flow and help to generate new approaches for therapeutic interventions.

Neointimal hyperplasia associated with synthetic hemodialysis grafts

Stenosis is a major cause of failure of hemodialysis vascular grafts and is primarily caused by neointimal hyperplasia (NH) at the anastomoses. The objective of this article is to provide a scientific review of the biology underlying this disorder and a critical review of the state-of-the-art investigational preventive strategies in order to stimulate further research in this exciting area. The histology of the NH shows myofibroblasts (that are probably derived from adventitial fibroblasts), extracellular matrices, pro-inflammatory cells including foreign-body giant cells, a variety of growth factors and cytokines, and neovasculature. The contributing factors of the pathogenesis of NH include surgical trauma, bioincompatibility of the synthetic graft, and the various mechanical stresses that result from luminal hypertension and compliance mismatch between the vessel wall and graft. These mechanical stimuli are focal in nature and may have a significant influence on the preferential localization of the NH. Novel mechanical graft designs and local drug delivery strategies show promise in animal models in preventing graft NH development. Successful prevention of graft stenosis would provide a superior alternative to the native fistula as hemodialysis vascular access.

Impact of Cuffed, Expanded Polytetrafluoroethylene Dialysis Grafts on Graft Outlet Stenosis

BACKGROUND

The objective of this study was to determine prospectively the difference between the graft outlet strictures of a polytetrafluoroethylene (ePTFE) graft with a cuff at the graft-vein anastomosis (Venaflo; Bard industries, Tempe, Ariz.) and that of the regular ePTFE graft (Stretch Gore-Tex; Gore, Flagstaff, Ariz.) placed for hemodialysis access.

METHODS

Between January and April 2005, 36 consecutive patients (average age: 63.3 years) underwent ePTFE graft implantation (36 implantations) for hemodialysis at the Vascular Surgery Section of Chang Gung Memorial Hospital. The patients of the study cohort were randomly assigned to two groups based on the graft used: cuffed graft group (Venaflo graft) and non-cuffed standard graft group (Gore-Tex graft). Each patient underwent antegrade venography at the 3-month follow-up to demonstrate the graft outlet stricture. Results of the graft outlet angiography analysis were examined, and all medical records were reviewed at end of the study. The degree of the graft outlet stenosis was compared between the two groups.

RESULTS

Average stenosis of the cuffed graft group and non-cuffed (standard) graft group were 22.76 +/- 26.37%% and 44.95 +/- 27.48%%, respectively; the difference between the two groups was statistically significant (P < 0.05).

CONCLUSIONS

The graft outlet stricture of cuffed ePTFE grafts for hemodialysis 3 months after implantation was less severe than that for the standard ePTFE graft. The correlation between the stricture level and dialysis graft patency requires further clarification.