Reinforced Aneurysmorrhaphy for True Aneurysmal Haemodialysis Vascular Access

Management of Arteriovenous Fistula After Successful Kidney Transplantation in Long-Term Follow-Up

Arteriovenous fistula (AVF) is the best method of vascular access for hemodialysis. This approach can lead to several complications, such as hyperkinetic heart failure due to a hyperfunctional AVF or dilatation of the feeding artery. These are late complications, especially in patients after a successful kidney transplantation. An observational study was performed focusing on patients more than 12 months after kidney transplantation. The AVF was evaluated by ultrasound and, if the outflow exceeded 1.5 L/min, an echocardiogram was performed. Surgical management was indicated if the cardiac index was higher than 3.9 L/min/m2 or upon finding a brachial artery aneurysm. A total of 208 post- kidney transplantation patients were examined over a 3-year period, of which 46 subjects (22.11%) had hyperfunctional AVF and 34 cases (16.34%) of feeding artery dilatation were determined. In total, 40 AVF flow reduction and 6 AVF ligation procedures were performed. The median AVF flow before and after the reduction was 2955 mL/min and 1060 mL/min, respectively. Primary patency after flow reduction was 88.3% at 12 months. Late AVF complications in patients following kidney transplantation are quite common. It is necessary to create a screening program to monitor AVFs in these patients.

External Support of Autologous Internal Jugular Vein Grafts with FRAME Mesh in a Porcine Carotid Artery Model

BACKGROUND

Autologous vein grafts are widely used for bypass procedures in cardiovascular surgery. However, these grafts are susceptible to failure due to vein graft disease. Our study aimed to evaluate the impact of the latest-generation FRAME external support on vein graft remodeling in a preclinical model.

METHODS

We performed autologous internal jugular vein interposition grafting in porcine carotid arteries for one month. Four grafts were supported with a FRAME mesh, while seven unsupported grafts served as controls. The conduits were examined through flowmetry, angiography, macroscopy, and microscopy.

RESULTS

The one-month patency rate of FRAME-supported grafts was 100% (4/4), whereas that of unsupported controls was 43% (3/7, Log-rank p = 0.071). On explant angiography, FRAME grafts exhibited significantly more areas with no or mild stenosis (9/12) compared to control grafts (3/21, p = 0.0009). Blood flow at explantation was higher in the FRAME grafts (145 ± 51 mL/min) than in the controls (46 ± 85 mL/min, p = 0.066). Area and thickness of neo-intimal hyperplasia (NIH) at proximal anastomoses were similar for the FRAME and the control groups: 5.79 ± 1.38 versus 6.94 ± 1.10 mm2, respectively (p = 0.558) and 480 ± 95 vs. 587 ± 52 μm2/μm, respectively (p = 0.401). However, in the midgraft portions, the NIH area and thickness were significantly lower in the FRAME group than in the control group: 3.73 ± 0.64 vs. 6.27 ± 0.64 mm2, respectively (p = 0.022) and 258 ± 49 vs. 518 ± 36 μm2/μm, respectively (p = 0.0002).

CONCLUSIONS

In our porcine model, the external mesh FRAME improved the patency of vein-to-carotid artery grafts and protected them from stenosis, particularly in the mid regions. The midgraft neo-intimal hyperplasia was two-fold thinner in the meshed grafts than in the controls.

Salvage Aneurysmorrhaphy as an Adaptable and Still Pertinent Technique in the Management of Challenging True Aneurysms of Arteriovenous Fistulas: A Case Series of Different Variations, With Illustrative Surgical Pictures

Introduction

Aneurysmorrhaphy, described as reduction aneurysmoplasty, partial aneurysmectomy, or vessel wall recalibration, can be considered a suitable surgical plan for true aneurysms of arteriovenous fistulas (AVFs), allowing for a dynamic approach to reconstruction of aneurysmal AVFs of different severities, ensuring salvage of the native access.

Report

Six challenging cases of AVF aneurysms are presented, some with extremely dilated and tortuous megafistulas, for which three surgical technique variations were performed. The patients had a mean age of 59.2 years, 50% were female, with brachiocephalic (n = 5, 83.3%) or brachiobasilic (n = 1, 16.7%) AVFs. The fistulas were created an average of 4.67 years previously, and the aneurysms had an average maximum diameter of 37.5 mm (range 25-60 mm). Surgical indications were rupture risk, thrombosis, or outflow stenosis compromising haemodialysis, infections, and concerns for quality of life (affected by post-puncture bleedings, disfiguring aesthetics, pain, and discomfort). The surgical techniques were simple aneurysmorrhaphy (n = 3, 50%), aneurysmorrhaphy with partial excision of aneurysmal segment with end to end anastomosis of venous ends (n = 2, 33.3%), and aneurysmorrhaphy with establishment of new venous outflow (n = 1, 16.7%). All AVFs were patent post-operatively and at follow up (mean 5.6 months, median one month). Haemodialysis was resumed through the AVFs at a mean of 2.17 weeks post-operatively, with placement of an alternative route for haemodialysis in the meantime. No patients experienced post-operative complications.

Discussion

Experience with the more challenging cases shows that aneurysmorrhaphy can still be considered an acceptable, flexible, and pertinent method for salvage of megafistulas, giving the surgeon the much needed versatility to adapt to anatomical and pathological variations, with high patency rates and minimal complications, especially when other treatment options are not possible in complicated cases. AVF salvage through aneurysmorrhaphy allows for a dynamic approach to the reconstruction of severely tortuous, dilated veins, ensuring patency of the native AVF.

A scoping review on surgical reduction of high flow arteriovenous haemodialysis access

Volume flow (Qa) > 1.5-2 l /minQa in arteriovenous accesses may be associated with high flow related systemic or locoregional complications. A variety of surgical techniques are advocated for Qa reduction. Aim of this scoping review is to provide an overview of available evidence regarding the efficacy of this broad spectrum of interventions for Qa reduction in patients with a high flow haemodialysis access. PubMed and Embase were searched according to PRISMA-guidelines. Studies on invasive management of HFA were selected. Inclusion required an English description of surgical techniques in human HFAs including pre- and postoperative access flow-values. Sixty-six studies on 940 patients (mean age 56 years (3-90 years), male 62%, diabetes mellitus 26%, brachial artery-based arteriovenous access 65%) fulfilled inclusion criteria. Performed techniques were banding (58%), revision using distal inflow (12%), plication/anastomoplasty (10%), graft interposition (5%), proximal radial artery ligation (3%), aneurysm repair (4%), or miscellaneous other techniques (8%). Definition of HFA, work-up, indication for surgery and intraoperative monitoring were diverse. All techniques reduced Qa on the short term (mean drop 0.9-1.7 l/min). Secondary access patency rates varied between 70% and 93% (mean follow-up 15 (0-189) months). Definitions of success and recurrence varied widely precluding a comparison of efficacy of techniques. Patient specific factors legitimizing invasive treatment for HFA are discussed. Recommendations on reporting standards when dealing with HFA surgery are provided. In conclusion, the present report on the current management of high flow access does not allow for drawing any definite conclusions due to a lack of standardization in definition, indications for surgical intervention and techniques. Randomized trials comparing different Qa reducing techniques in symptomatic patients are warranted, as are trials comparing a wait-and-see approach versus Qa reduction in asymptomatic patients. As an overview of the variety of techniques was lacking, this scoping review might serve as a map for future researchers.

Outcomes of one-stage and two-stage aneurysm repair in arteriovenous fistulae

OBJECTIVE

Maintenance of long-term arteriovenous access is important in long-term care for patients with end-stage renal disease. Arteriovenous access is associated in the long term with the development of fistula aneurysms (FAs). This study aims to evaluate the outcomes of staged FA treatment in dialysis access arteriovenous fistulae (AVF).

METHODS

A retrospective review of all patients over a 12-year period with primary autogenous AVF was undertaken at a single center. Patients undergoing elective open aneurysm repair were identified and were categorized into three groups: single FA repair (single, control group) and staged and unstaged repair of two FAs (staged and unstaged). A staged repair was a procedure in which the initial intent was to treat both aneurysms in the AVF and in which the most symptomatic aneurysm was treated first. When the incision from the first surgery had healed, the second symptomatic aneurysm in the AVF was treated. An unstaged repair was a procedure in which the initial intent was to repair both symptomatic aneurysms simultaneously. All patients had a fistulogram before the FA repair. Thirty-day outcomes, cannulation failure, line placement, reintervention, and functional dialysis (continuous hemodialysis for 3 consecutive months) were examined.

RESULTS

Five hundred twenty-seven patients presented with FA that met requirements for open intervention; 44% underwent single FA repair, whereas the remaining 34% and 22% underwent staged and unstaged repair of two FAs, respectively. The majority of patients were diabetic and Hispanic. Ninety-one percent of the patients required percutaneous interventions of the outflow tract (37%) and the central veins (54%). Thirty-day major adverse cardiovascular events were equivalent across all modalities. Thirty-day morbidity and early thrombosis (<18 days) were significantly higher in the unstaged group (4.3%) compared with the two other groups (1.3% and 2.1%, single and staged, respectively), which led to an increased need for a short-term tunneled catheter (8.9%) compared with the two other groups (3.4% and 4.4%, single and staged, respectively), Unstaged repair resulted in an increased incidence of secondary procedures (5.0%) compared with the two other groups (2.6% and 3.1%, single and staged, respectively). Functional dialysis at 5 years was equivalent in the single and staged groups but was significantly decreased in the unstaged group.

CONCLUSIONS

Open interventions are successful therapeutic modalities for FAs, but unstaged rather than staged repair of two concurrent FAs results in a higher early thrombosis, an increased secondary intervention rate, and a need for a short-term tunneled central line. Staged and single FA repairs have equivalent results. In the setting of two symptomatic FAs, staged repair is recommended.

Management of an aneurysmal arteriovenous fistula in kidney transplant recipients

Aneurysms remain the most common complication of an arteriovenous fistula created for dialysis access. The management of an aneurysmal arteriovenous fistula (AAVF) in kidney transplant recipients remains contentious with a lack of clear clinical guidelines. Recipients of a functioning graft do not require the fistula for dialysis access, however risk of graft failure and needing the access at a future date must be considered. In this review we outline the current evidence in the assessment and management of a transplant recipient with an AAVF. We will describe our recommended five-step approach to assessing an AAVF in transplant patients; 1.) Define AAVF 2.) Risk assess AAVF 3.) Assess transplant graft function and future graft failure risk 4.) Consider future renal replacement therapy options 5.) Vascular mapping to assess future vascular access options. Then we will describe the current therapeutic options and when they would most appropriately be employed.

Surgical Referral for Hemodialysis Access Maintenance

Hemodialysis access is the lifeline for end-stage renal disease patients. However, dialysis access is associated with a host of complications, including thrombosis, recurrent stenosis, infection, aneurysmal changes and bleeding. Although endovascular therapy remains the first-line treatment owing to its less invasive nature, there are certain situations where surgical referral is recommended or even necessary. Regardless, management of dialysis access complications requires a multidisciplinary approach. Interventional radiologists should be familiar with the appropriate timing for surgical referral to better serve the complex patient population.

Revision of Aneurysmal Arteriovenous Access with Immediate Use Graft Is Safe and Avoids Prolonged Use of Tunneled Hemodialysis Catheters

INTRODUCTION

Aneurysmal AVF can pose a difficult treatment dilemma for the vascular surgeon. Prolonged tunneled dialysis catheters (TDC) in patients requiring long-term dialysis are associated with significantly increased mortality compared to arteriovenous fistulas (AVF). We aimed to elucidate the outcomes of aneurysmal AV access revision with aneurysm resection and Artegraft® (LeMaitre, New Brunswick, NJ) Collage Vascular Graft placement to avoid prolonged use of TDCs.

METHODS

We reviewed all patients with aneurysmal AV access in which the access was revised with aneurysm resection and jump graft placement at a single institution from 2018 to 2021. Outcomes were time to cannulation, reintervention rates, time to reintervention and patency (primary, primary assisted and secondary). Patency rates were estimated with Kaplan-Meier Survival analysis.

RESULTS

A total of 51 revised aneurysmal AV access in 51 patients were studied, of which 23.5% (n=12) had perioperative TDC placement. Three patients were done for emergent bleeding. The cohort was 62.8% male (n=32) with a median age of 58 years (IQR: 49-67). Most patients had brachiocephalic AVF (n=37 [72.6%]). Median follow up time was 280 days. Median time to cannulation was 2 days. Time to cannulation was significantly longer in patients with perioperative TDC as compared with those without TDC (24 days vs 2 days, P<0.001). Reintervention was required in 41.2% of patients (n=21), at median time of 47 days. At 30, 90, 180, and 365 days, primary patency rates were 84.3%, 78.3%, 66.6%, and 54.9%; primary assisted patency rates were 94.1%, 88.1%, 79.4%, and 79.4% and secondary patency rates were 100%, 97.8%, 91.6% and 91.6% respectively.

CONCLUSIONS

Revision of aneurysmal AV access (urgent or elective) with Artegraft as jump graft is safe, with acceptable short and mid-term patency results. This allows dialysis patients to continue to have a functional access, decreasing the need for a tunneled catheter and reducing the associated risk of sepsis and increased mortality. This should be considered for all patients with aneurysmal, dysfunctional fistulas to maintain AV access and avoid TDC placement.

[Surgical treatment of true aneurysms of permanent vascular access]

Analyzed herein are the results of surgical treatment of true diffuse aneurysms of the permanent vascular access in 44 patients. Of these, there were 29 men and 15 women, mean age 48.1±2.3 years (19-78 years). The average time having elapsed since the formation of the native access was 109.4±9.5 months (12-276, median - 108 months). The indications for surgical treatment were as follows: haemorrhage including recurrent bleedings (3), thrombosis of the permanent vascular access (26), its dysfunction (5), high flow syndrome (3), large-size aneurysm with disordered function of the limb, pain syndrome or a pronounced cosmetic defect (7). In 14 cases, reconstruction was not performed. We carried out ligating operations, in some instances with partial removal of the aneurysm and establishing a new vascular access. 3 patients underwent resection of the aneurysm with replacement by a graft. In the remote period 1 patient at 46 months developed infection of the prosthesis, resulting in loss of the access. Follow up of the remaining 2 patients demonstrated satisfactory function of the vascular access at 6 and 60 months. 16 patients were subjected to total plasty of the aneurysm using autotissues. On a cylindrical template measuring 6 mm in diameter after dissection of excessive tissues along the posterior wall of the vein, an uninterrupted suture was formed followed by placing the formed transplant into a new bed. 11 patients underwent the operation according to the analogous technique, but the formed autotransplant was reinforced with a thin-wall exoprosthesis made of polytetrafluoroethylene up to 0.2-mm thick and 10 mm in diameter ('Ecoflon'). Two (12.5%) of 16 patients subjected to reconstruction of the aneurysm without reinforcement developed haemorrhage in the early postoperative period, and one developed thrombosis thus resulting in loss of the access. In-hospital patency amounted to 81.3%. In plasty with reinforcement, there were no complications in the early postoperative period. Long-term primary patency after total plasty without reinforcement at 1, 3, and 5 years amounted to 68.2±11.8%, 56.8±14.3%, and 22.7±13.7%, respectively, with secondary patency of 68.2±11.8% at the above-mentioned terms. In the majority of patients aneurysmatic transformation of the transplant occurred again in the remote period. Primary patency at 1, 3 and 4 years after plasty with reinforcement amounted to 80.8±12.2%, 80.8±12-2% and 60.6±19.8%, respectively, with the secondary patency rates of 90.9±8.7% at the above mentioned terms.

[Complications of permanent vascular access for haemodialysis]

Permanent vascular access is the basis of renal replacement therapy by the method of programmed haemodialysis, on whose stable functioning depends the life of patients with end-stage renal disease. At the present time, there is significant deficit of scientific and methodological Russian-language literature on this problem, with no Russian consensus documents concerned. This article is a review of the contemporary world literature dedicated to the problem of permanent vascular access, including currently in force European (2018) and North American (2019) guidelines for good clinical practice, also discussing the problems of strategy and tactics of creating a permanent vascular access, monitoring its dysfunction, pathophysiology of functioning of arteriovenous fistulas. Presented herein are unified approaches to diagnosis and treatment of thrombolytic and haemorrhagic complications associated with the access, as well as local infectious and non-infectious complications. Special attention is paid to indications for the operation and rational therapeutic decision-making.

Upper extremity reconstruction following open surgical repair of giant arteriovenous fistula aneurysm: clinical case and systematic review of the literature

Background:

Nearly 30% of arteriovenous fistulas (AVFs) located in the upper extremity for hemodialysis access result in short- and long-term adverse effects, such as rupture, necessitating emergent surgical management and extensive soft-tissue reconstruction. With this systematic review, we aimed to compile all reported open surgical techniques used for complicated AVF repair in the upper extremity, the respective soft-tissue reconstructive outcomes, and vascular patency rates at final follow-up.

Methods:

Using Ovid Medline/PubMed databases, we conducted a review of the English-language literature on AVF aneurysm surgical management in the upper extremity, filtered for relevance to open surgical technique and outcomes in vascular patency after aneurysmal repair at long-term follow-up (≥6 months postoperatively). We include a detailed case of surgical removal of a giant AVF aneurysm and subsequent flap elevation and reconstruction of the upper extremity.

Results:

Of 150 articles found in the initial search, 19 (from 2010-2017) met inclusion criteria. From the reviewed studies, 675 patients underwent open surgical repair of AVF aneurysm in the upper extremity. Surgical approaches included partial-to-full aneurysm excision, interposition graft, tubularized extracellular matrix, sutured and stapled aneurysmorrhaphy, and stent graft. Rates of vascular patency at repair site ranged from 47% to 100%, with a pooled average of 78% at 6 months or longer postoperatively.

Conclusions:

For plastic and hand surgeons, aneurysmal ligation and excision is feasible even in severe cases and is associated with overall good vascular and soft-tissue reconstructive outcomes in the upper extremity. (www.actabiomedica.it)

KDOQI Clinical Practice Guideline for Vascular Access: 2019 Update

The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) has provided evidence-based guidelines for hemodialysis vascular access since 1996. Since the last update in 2006, there has been a great accumulation of new evidence and sophistication in the guidelines process. The 2019 update to the KDOQI Clinical Practice Guideline for Vascular Access is a comprehensive document intended to assist multidisciplinary practitioners care for chronic kidney disease patients and their vascular access. New topics include the end-stage kidney disease "Life-Plan" and related concepts, guidance on vascular access choice, new targets for arteriovenous access (fistulas and grafts) and central venous catheters, management of specific complications, and renewed approaches to some older topics. Appraisal of the quality of the evidence was independently conducted by using a Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, and interpretation and application followed the GRADE Evidence to Decision frameworks. As applicable, each guideline statement is accompanied by rationale/background information, a detailed justification, monitoring and evaluation guidance, implementation considerations, special discussions, and recommendations for future research.

Stent graft deployment in haemodialysis fistula: patency rates in partially thrombosed aneurysm and residual thrombi

Background

Current evidence is insufficient to determine the contribution of stent grafts as treatment in partially thrombosed aneurysms or residual wall-adherent thrombi in arteriovenous fistulae (AVFs) for haemodialysis. The overall purpose of this study was to analyse patency rates of post-interventional covered stent deployment in those cases. We also assessed if patency rates differed when fistulas were punctured through the stent during dialysis sessions.

Methods

We conducted a retrospective study between 2006 and 2014 analysing post-intervention primary patency rates using the Kaplan-Meier log-rank test. Multivariate Cox proportional regression models were performed to determine if cannulation within the stent graft area was a potential risk factor for occlusion, by adjusted hazard ratio (HR).

Results

A total of 27 procedures were included in the study. Primary patency rates (%) after stent deployment at 3, 6, 12, 24, 36 and 72 months were, respectively: total 59, 32, 32, 21, 11 and 5; stent puncture 53, 21, 21, 16, 5 and 0; and no stent puncture 80, 80, 80, 40, 40 and 40. Cannulation through the stent graft was not significantly associated with increased risk of obstruction in multivariate analysis (HR = 3.01; P = 0.286).

Conclusion

Stent graft treatment may be a feasible procedure in partially thrombosed aneurysms and residual thrombi in AVF. Although fistulas punctured through the stent presented lower patency rates, this practice was not associated with a higher risk of obstruction. Giving the impossibility of comparing with similar approaches, further studies are needed to confirm or refute the advantages of this procedure.

[Conservative aneurysmorrhaphy for hemodialysis arteriovenous fistula]

The aim of this study was to evaluate the results of conservative surgical treatment of the aneurysmal complications of arteriovenous hemodialysis fistulae and to determine the factors predictive of long- and mid-term patency of treated fistulae. The surgical treatment was mainly based on caliber reduction and reconstruction.

METHODS

This was a descriptive retrospective study with a five-year duration, going from January 2013 to December 2018. This study included 40 patients presenting aneurysmal complications of their hemodialysis vascular access who were treated with aneurysmorrhaphy.

RESULTS

The mean age of the aneurysmal-complicated hemodialysis vascular access was 42 months. The indications for treatment were puncture-related difficulties in 42.5% of cases, rapid increase of the aneurysmal diameter in 27.5%, skin thinning in 25% and aneurysmal rupture in 5%. The mean aneurysmal course was 6.6 months with an average diameter of 3.25cm at the moment of management. The initial technical success rate was 100%. Twenty patients had complications in the postoperative period. Patency rates at 3, 6, 12 and 24 months were 89.5%, 81.6%, 71% and 63.1%, respectively. Factors predictive of thrombosis were diabetes (P=0.001), peripheral arterial disease (P=0.003), number of punctures per week (P=0.003) and context of emergency presentation (P=0.001).

CONCLUSION

Aneurysmorrhaphy seems to be the best conservative surgical treatment for aneurysmal complications of hemodialysis vascular access fistulae. This surgical approach allows us to conserve the native autologous vascular access and spare the patient's venous network.

Partial aneurysmectomy for treatment of autologous hemodialysis fistula aneurysm is safe and effective

OBJECTIVE

The purpose of this study was to evaluate the outcome and the factors associated with stenosis after treatment using partial aneurysmectomy for aneurysm in autologous arteriovenous fistulas.

METHODS

This retrospective cohort study was conducted from July 2007 to June 2016 and included patients with complicated aneurysms in upper extremity autologous arteriovenous fistulas were treated by partial aneurysmectomy. Vascular ultrasound examination was performed every 6 months after the surgery.

RESULTS

Forty-one patients (median age, 37 years; 70.7% males) were included. Of the patients, 95.1% had a radial-cephalic fistula in the forearm and nearly 88% had 1 or 2 aneurysms in arteriovenous fistulas that had been created for 10 to 84 months. Technical success of partial aneurysmectomy was achieved in all patients. The access diameter (44.0 ± 5.1 mm vs 10.4 ± 1.8 mm; P < .01) and brachial artery blood flow (1618.2 ± 277.0 mL/min vs 772.1 ± 127.4 mL/min; P < .01) were significantly decreased after the surgery. The median follow-up time was 27 months (range, 12-43 months). The primary patency rates at 6 and 12 months were 100% and 95%, respectively. Loss of patency was due to stenosis of the remodeled fistulas, which occurred in seven patients (17%). Multivariate COX regression analysis revealed that diabetes (hazard ratio, 114.28; 95% confidence interval, 2.85-4583.94; P = .01) was a risk factor for the impaired primary patency rates. A larger postprocedure residual diameter trended to favor fistula patency (hazard ratio, 0.46; P = .07). Stenosis was successfully treated with percutaneous transluminal angioplasty.

CONCLUSIONS

Partial aneurysmectomy is an effective and safe method for treating aneurysm of upper extremity autologous arteriovenous fistulas, leading to good 12-month primary patency and no aneurysm recurrence. Using a larger catheter to size the revised fistula during aneurysmectomy may increase access patency.

Graft Inclusion Technique: A New Flow Reduction Procedure for High Flow Arteriovenous Fistulae

Objective: Flow reduction is required to preserve vascular access in cases with high flow access (HFA). We report a new flow reduction procedure, the graft inclusion technique (GIT).

Methods: The GIT procedure developed by us involves the intraluminal placement and suturing of a 4-mm polytetrafluoroethylene graft to the anastomosis and outflow tract to plicate the enlarged anastomosis and maintain lower flow volumes. Flow reduction for HFA was retrospectively assessed in a series of 25 patients (age 65±12 years; 17 males and 8 females) to evaluate flow volume and patency rate, wherein 10 patients underwent conventional methods of flow reduction and 15 underwent GIT.

Results: Compared with preprocedure values, mean flow volume (MFV) was significantly lower after the procedure with both the conventional methods (1,817 vs. 586 ml/min; P<0.05) and the GIT (2,262 vs. 890 ml/min; P<0.05). An increase in MFV occurred during follow-up after conventional flow reduction (586 vs. 1,036 ml/min), while GIT could maintain lower MFV (890 vs. 791 ml/min), suggesting that GIT can significantly lower MFV levels (2,262 vs. 791 ml/min; P<0.05) and maintain these lower MFV levels during follow-up. Secondary patency rate for the GIT was 100% at 1 year and 83% at 3 years.

Conclusion: The GIT may be used as an access-preserving, reliable, long-term, and stable flow-reducing procedure that does not require flow adjustment during surgery.

Aneurysms in Vascular Access: State of the Art and Future Developments

A master class was held at the Vascular Access at Charing Cross (VA@CX2017) conference in April 2017 with invited experts and active audience participation to discuss arteriovenous (AV) vascular access aneurysms, a serious and common complication of vascular access (VA). The natural history of aneurysms in VA is poorly defined, and although classifications exist they are not uniformly applied in studies or clinical practice. True and pseudo aneurysms of AV access occur. Whilst an AV fistula by definition is an abnormal dilatation of a blood vessel, an agreed definition of 18 mm, or 3 times accepted maturation diameter, is proposed. The mechanism of aneurysmal dilatation is unknown but appears to be a combination of excessive external remodeling, wall changes due to injury, and obstruction of outflow. Diagnosis of AV aneurysms is based on physical examination and ultrasound. Venography and cross-sectional imaging may assist and be required for the investigation of outflow stenosis. Treatment of pseudo aneurysms and true aneurysms of VA (AVA) is not evidence-based, but relies on clinical experience and available facilities. In many AVA, a conservative approach with surveillance is suitable, although intervals and modalities are unclear. Avoidance of rupture is imperative and preemptive treatment should aim for access preservation, ideally with avoidance of prosthetic materials. Different techniques of aneurysmorrhaphy are described with good results in published series. Although endovascular approaches and stenting are described with good short-term results, issues with cannulation of stented areas occur and, while possible, this is not recommended, and long-term access revision is recommended.

Cardiac remodeling after reduction of high-flow arteriovenous fistulas in end-stage renal disease

In patients with end-stage renal disease, excessive blood flow through an arteriovenous fistula (AVF) may lead to volume overload-induced cardiac remodeling and heart failure. It is unclear which patients with hyperfunctional AVF may benefit from AVF reduction or ligation. The indication for the procedure is often based on AVF flow. Because cardiac remodeling is driven by increased venous return, which is equivalent to cardiac output, we hypothesized that an elevated cardiac index (CI) might better identify subjects with reverse remodeling after AVF reduction. Thirty patients (age 52±12 years, 73% male) with AVF flow ⩾1.5 l min(-1) underwent comprehensive echocardiographic evaluations before and after AVF reduction. At baseline, 16 patients had a normal CI (2.5-3.8 l min(-1) m(-2)) and 14 had a high CI (4.0-6.0 l min(-1) m(-2)). A left ventricular end-diastolic diameter decrease after operation was predicted by elevated baseline CI (P<0.01), but not elevated AVF flow (P=0.07). There was a significant decrease in CI, left ventricular mass, left atrial and right ventricular diameter and pulmonary systolic pressure in the high CI group but not in the normal CI group. After AVF reduction, systemic vascular resistance decreased in the normal CI group, whereas it did not change in the high CI group. In conclusion, reduction of high-flow AVF leads to reverse cardiac remodeling but only in patients with elevated CI. The variability of the response of systemic vascular resistance to AVF flow may explain this observation. Increased CI but not increased AVF flow may better determine candidates for AVF reduction.

True aneurysm in autologous hemodialysis fistulae: definitions, classification and indications for treatment

Introduction

Definition, etiology, classification and indication for treatment of the arteriovenous access (AVA) aneurysm are poorly described in medical literature. The objectives of the paper are to complete this information gap according to the extensive review of the literature.

Methods

A literature search was performed of the articles published between April 1, 1967, and March 1, 2014. The databases searched included Medline and the Cochrane Database of Systematic Reviews. The eligibility criteria in this review studies the need to assess the association of aneurysms and pseudoaneurysms with autologous AVA. Aneurysms and pseudoaneurysms involving prosthetic AVA were not included in this literature review. From a total of 327 papers, 54 non-English papers, 40 case reports and 167 papers which did not meet the eligibility criteria were removed. The remaining 66 papers were reviewed.

Results

Based on the literature the indication for the treatment of an AVA aneurysm is its clinical presentation related to the patient's discomfort, bleeding prevention and inadequate access flow. A new classification system of AVA aneurysm, which divides it into the four types, was also suggested.

Conclusions

AVA aneurysm is characterized by an enlargement of all three vessel layers with a diameter of more than 18 mm and can be presented in four types according to the presence of stenosis and/or thrombosis. The management of an AVA aneurysm depends on several factors including skin condition, clinical symptoms, ease of cannulation and access flow. The diameter of the AVA aneurysm as a solo parameter is not an indication for the treatment.