Arteriovenous Fistula Maturation Research Articles

Predicting Dialysis Fistula Maturation Using the “Rule of 6’S”—Not All are Created Equal

The rule of 6's (Ro6; flow volume >600 mL/min; vein diameter >6 mm; vein depth <6 mm) is a widely used informal guide to determine when an arteriovenous fistula (AVF) will support dialysis. We tested the utility of the Ro6 in clinical practice. We retrospectively reviewed AVFs created at a single center from 2016 to 2019 in patients who had received dialysis in the same network. For each AVF, we reviewed the clinical records and postoperative ultrasound studies (including flow measurement) for Ro6 criteria. Maturation was defined as use of the AVF with two needles for 75% of dialysis sessions during a continuous 4-week period with mean flow of 300 mL/min or Kt/V of 1.2. The predictors of maturation were assessed using logistic regression and receiver operating characteristics curves after stratifying AVFs by type. P < .05 was considered significant. A total of 202 AVFs of three different types met the inclusion criteria (radiocephalic, n = 49; brachiocephalic, n = 87; brachiobasilic, n = 66). Maturation occurred in 150 AVFs (74%) (primary, n = 101 [50%]; assisted, n = 49 [24%]), and 52 (26%) failed to mature. Maturation did not vary by AVF type, sex, or diabetes status. However, a higher body mass index (BMI) was associated with failure to mature (P = .004). For all types, one or more Ro6 criteria were satisfied in significantly more mature AVFs than in those that failed to mature (55% vs 36%; P = .009). Only 16 mature AVFs (11%) met all three Ro6 criteria; however, all mature AVF met more than one criterion. On multivariable analysis (Table I), each Ro6 criterion was independently associated with maturation. If all three were met, the AVF was 10 times more likely to be mature compared with an AVF meeting no criteria. The BMI correlated strongly with vein depth (P < .001); however, both characteristics independently predicted for maturation. The chance of maturation was highest if the flow and depth criteria were met (positive predictive value, 93), marginally better than if all three criteria were met (positive predictive value, 92; Table II). The receiver operating characteristic area under curve for meeting the flow volume and vein depth criteria together were slightly greater than if all three Ro6 criteria were met (also true for each AVF type; data not shown). The Ro6 predicts for AVF maturation but only a small minority of mature AVFs will meet all three criteria. Flow volume and vein depth together predicted for maturation equally as well as meeting all three criteria. Meeting the vein diameter criterion seems less important. A higher BMI was associated with AVF failure, independent of vein depth.Table IMultivariable logistic regression of independent predictors of functional AVF maturationVariableOR95% CIP valueAny flow volume >600 mL/min6.773.09-14.86<.001Any depth <6 mm3.301.31-8.29.011Any diameter >6 mm4.051.53-10.76.005All three criteria9.804.40-21.82<.001BMI0.930.89-0.98.003Age1.010.98-1.04.581BMI, Body mass index; CI, confidence interval; OR, odds ratio. Open table in a new tab Table IITest characteristics and ROC AUC analysis for functional AVF maturationVariableSensitivity, %Specificity, %PPV, %NPV, %ROC AUCAny flow volume >600 mL/min807390560.765Any depth <6 mm874482540.655Any diameter >6 mm912778500.588All three criteria688392470.754Flow + diameter only747389490.735Flow + depth only748393520.784Diameter + depth only776787510.732AUC, Area under the curve; AVF, arteriovenous fistula; ROC, receiver operating characteristic; NPV, negative predictive value; PPV, positive predictive value. Open table in a new tab

Balloon Assisted Maturation With Large Balloons Should Be First-Line Intervention for Marginal Arteriovenous Fistulas

Balloon assisted maturation (BAM) is a well-established method to develop functional arteriovenous fistulas (AVFs) but often requires multiple reinterventions. To achieve maturation, AVFs must be ∼6 mm in diameter. We hypothesized that larger diameter balloons (8 mm) would be needed to account for recoil during angioplasty and to achieve earlier maturation and a decreased number of interventions. We evaluated the outcomes of initial BAM with large diameter balloons. A retrospective review of 182 patients who had undergone BAM between 2018 and 2020 in an academic medical center was performed. The cohort was divided into two groups. Group I included patients who had undergone initial BAM with an 8-mm balloon (n = 128), and group II included patients who had undergone initial BAM with a <8-mm balloon (n = 54). An 8-mm balloon was not used if extravasation was observed after angioplasty with a smaller balloon. The AVF was considered matured if successfully used for dialysis on three consecutive sessions without further interventions. A total of 234 BAMs were performed: 150 in group I and 84 in group II. All demographics were similar between the two groups. The preprocedure duplex ultrasound showed no differences in the vein size (4.6 ± 1.1 mm vs 3.9 ± 1.2 mm; P = .705), volume flow (705 ± 426 mL/min vs 461 ± 354 mL/min; P = .631), or incidence of AVF stenosis (11.1% vs 1.6%; P = .189) between the two groups. The overall maturation rate was 95% (173 of 182) and was 98.4% in group I and 87% in group II (P = .001). Of the 150 AVFs in group I, 107 (83.5%) achieved maturation after the initial BAM compared with 23 of 84 AVFs (42.5%) in group II (P = .001). The incidence of intraprocedural contrast extravasation and postprocedural hematoma was similar between the two groups (11.7% vs 16.6%; P = .367). None of the complications required intervention nor did they affect AVF patency. The dialysis catheter dwell time was longer in group II than in group I (125 ± 56 days vs 112 ± 42 days; P = .034). The mean AVF diameter after BAM was 6 ± 1.4 mm in group I and 5.1 ± 1.5 mm in group II (P = .992). We conclude that BAM with large diameter balloons is safe and leads to higher AVF maturation rates and fewer reinterventions without an increased rate of complications. It also results in lower catheter dwell times, which might prevent long-term catheter complications. Our data support the theory that larger balloons are needed to achieve a 6-mm AVF diameter owing to vessel recoil after angioplasty.

Arteriovenous Fistula Maturation, Functional Patency, and Intervention Rates

National initiatives have emphasized the use of autogenous arteriovenous fistulas (AVFs) for hemodialysis, but their purported benefits have been questioned. To examine AVF usability, longer-term functional patency, and remedial procedures to facilitate maturation, manage complications, or maintain patency in the Hemodialysis Fistula Maturation (HFM) Study. The HFM Study was a multicenter (n = 7) prospective National Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases cohort study performed to identify factors associated with AVF maturation. A total of 602 participants were enrolled (dialysis, kidney failure: 380; predialysis, chronic kidney disease [CKD]: 222) with AVF maturation ascertained for 535 (kidney failure, 353; CKD, 182) participants. All clinical decisions regarding AVF management were deferred to the individual centers, but remedial interventions were discouraged within 6 weeks of creation. In this case series analysis, the primary outcome was unassisted maturation. Functional patency, freedom from intervention, and participant survival were summarized using Kaplan-Meier analysis. Most participants evaluated (n = 535) were men (372 [69.5%]) and had diabetes (311 [58.1%]); mean (SD) age was 54.6 (13.6) years. Almost two-thirds of the AVFs created (342 of 535 [64%]) were in the upper arm. The AVF maturation rates for the kidney failure vs CKD participants were 29% vs 10% at 3 months, 67% vs 38% at 6 months, and 76% vs 58% at 12 months. Several participants with kidney failure (133 [37.7%]) and CKD (63 [34.6%]) underwent interventions to facilitate maturation or manage complications before maturation. The median time from access creation to maturation was 115 days (interquartile range [IQR], 86-171 days) but differed by initial indication (CKD, 170 days; IQR, 113-269 days; kidney failure, 105 days; IQR, 81-137 days). The functional patency for the AVFs that matured at 1 year was 87% (95% CI, 83.2%-90.2%) and at 2 years, 75% (95% CI, 69.7%-79.7%), and there was no significant difference for those receiving interventions before maturation. Almost half (188 [47.5%]) of the AVFs that matured had further intervention to maintain patency or treat complications. The findings of this study suggest that AVF remains an accepted hemodialysis access option, although both its maturation and continued use require a moderate number of interventions to maintain patency and treat the associated complications.

Arteriovenous fistula formation with adjuvant endovascular maturation

BackgroundThe clinical utility of the native arteriovenous fistula (AVF) has been limited by the prolonged time required for maturation, the low overall maturation rate, and subsequent abandonment. Endovascular intervention has been increasingly accepted as the first-line therapy for AVF stenosis. The objective of the present study was to evaluate the AVF formation outcomes when early endovascular intervention was selectively performed to bring about timely AVF maturation. MethodsWe performed a retrospective study (February 2014 to February 2020) of 82 AVF consecutive patients (mean age, 62.5 ± 13.5 years; range, 17-83; 58 men [70.7%]) with end-stage renal failure who had undergone vascular access construction at a single institution. The 4-year AVF patency, vascular diameters, hemodialysis parameters, reintervention rate, and mortality were analyzed. ResultsRadiocephalic AVF was the most common fistula constructed (71 patients; 88.6%). The evaluation at a mean of 46.2 ± 56.0 days (range, 5-343 days) after AVF formation revealed 33 immature AVFs (40.2%). Subsequently, 19 patients had undergone endovascular procedures, including angioplasty and/or stenting of the juxta-anastomosis, cannulation zones, and/or outflow segments to bring about timely maturation of the AVF. Hence, 93.9% of the AVFs had reached functional patency (maturation) by 6 months after formation, with a mean time to maturation of 67.8 ± 65.9 days (range, 5-320 days). After reaching maturation, the primary access functional patency was 82% ± 4.3% at 6 months, 58% ± 5.5% at 12 months, and 34% ± 6.8% at 48 months. The primary assisted access functional patency was 95% ± 2.4% at 6 months, 90% ± 3.3% at 12 months, and 83% ± 4.7% at 48 months. A total of 121 endovascular interventions were performed to maintain patency, equating to an endovascular reintervention rate of 0.37 procedure/patient year. The mean arterial, venous, and brachial flow rates did not change significantly after maturation with a mean AVF (primary assisted functional patency) survival time of 5.9 ± 0.26 years (range, 5.33-6.36 years) from maturation. Only 12 thromboses had occurred after the first follow-up review after AVF formation. These were all salvaged using endovascular techniques, leading to 100% total secondary functional patency at 4 years. The 5-year estimated all-cause mortality was 45.6% ± 12.7%. ConclusionsThe AVF maturation rate and interval to maturation were improved when early endovascular intervention was selectively performed after AVF formation. This allowed for near universal maturation. In addition, once matured, the use of ongoing endovascular reinterventions allowed for a low reintervention rate and long-term patency, providing reliable long-term renal vascular access.

Vein and artery diameter influence on arteriovenous fistula maturation and patency in a Mexican population.

There is no consensus of the optimal arterial and venous sizes on arteriovenous fistula (AVF) function and patency. The purpose of our study was to determine the influence of vein and artery sizes on maturation and patency in autologous first time AVF in a vascular access clinic of Mexican Social Security. Approved IRB single-center retrospective study in patients referred for their first AVF from 01/2018/ to 04/2020. Perianastomotic inner vein diameter and single inner artery diameter was recorded by duplex ultrasound. Outcomes were: failure to mature (FTM) and cumulative primary patency survival. Eighty-six AVF's were created (mean age 45.5 ± 15.1 years; 62.8% male; mean BMI 25.9 ± 4.3 kg/m2). About 86% were brachiocephalic AVF. Eight (8.1%) AVF had FTM. Mean follow-up was 19.7 ± 8.5 months. Two-year patency survival was 81.4%. FTM vein and artery diameters (2.1 ± 0.3 and 2.8 ± 0.7 mm respectively) were smaller than successful AVF's (3.1 ± 0.9 and 3.5 ± 0.6 mm) (p < 0.05). ROC curve calculated a 2.15 mm vein diameter cutoff (AUC: 0.86) and a 2.95 mm artery diameter cutoff (AUC: 079) for FTM AVF's (83% sensitivity, 72% specificity both) (p < 0.05). AVF's created with a vein diameter <2.15 mm and <2.95 mm artery diameter had statistically significant lower patency survival than AVF's with larger vein and artery diameters (p < 0.05). Vein diameter <2.15 mm and artery diameter <2.95 mm influences AVF maturation and patency in a Mexican population.

Effect of far infrared therapy on arteriovenous fistula maturation, survival and stenosis in hemodialysis patients, a randomized, controlled clinical trial: the FAITH on fistula trial

BackgroundAn arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis treatment. After creation many of the AVFs will never mature or if functioning will need an intervention within 1 year due to an AVF stenosis. Studies investigating possible therapies that improves the AVF maturation and survival are scarce. Far infrared therapy (FIR) has shown promising results. In minor single centre and industry supported trials FIR has shown improved AVF maturation and survival. There is a need of a randomized multicentre controlled trial to examine the effect of FIR on the AVF maturation and survival and to explore the possible AVF protective mechanism induced by the FIR treatment.MethodsThis investigator initiated, randomized, controlled, open-labeled, multicenter clinical trial will examine the effect of FIR on AVF maturation in patients with a newly created AVF (incident) and AVF patency rate after 1 year of treatment in patients with an existing AVF (prevalent) compared to a control group. The intervention group will receive FIR to the skin above their AVF three times a week for 1 year. The control group will be observed without any treatment. The primary outcome for incident AVFs is the time from surgically creation of the AVF to successful cannulation. The primary outcome for the prevalent AVFs is the difference in number of AVFs without intervention and still functioning in the treatment and control group after 12 months. Furthermore, the acute changes in inflammatory and vasodilating factors during FIR will be explored. Arterial stiffness as a marker of long term AVF patency will also be examined.DiscussionFIR is a promising new treatment modality that may potentially lead to improved AVF maturation and survival. This randomized controlled open-labelled trial will investigate the effect of FIR and its possible mechanisms.Trial registrationClinicaltrialsgov NCT04011072 (7th of July 2019).

Balloon-assisted Maturation With Larger Diameter Balloons Should Be First-line Intervention for Nonmaturing Autologous Hemodialysis Access

Serial balloon-assisted maturation (BAM) is a well-established method to develop functional arteriovenous fistulas (AVFs) but often require multiple reinterventions. We hypothesized that initial BAM with a larger diameter balloon will lead to earlier maturation of AVF and lower rates of reintervention. A retrospective review of 173 consecutive patients who underwent BAM between 2018 and 2020 by a single vascular surgeon at a hospital setting was performed. The cohort was divided into Group I: patients that underwent initial BAM with an 8-mm balloon (n = 121), and Group II: patients that had initial BAM with <8-mm balloon (n = 52). An 8-mm balloon was not used if contrast extravasation was observed after angioplasty with a smaller balloon. Only procedures performed to achieve initial AVF maturation were included, and procedures performed to maintain access patency were excluded. AVF was considered matured if successfully used for dialysis on 3 consecutive sessions. Demographic data, procedural details, and outcomes were compared between the two groups. A total of 222 BAMs were performed: 152 in Group I and 70 in Group II. The overall maturation rate was 99% (172/173). All demographics were similar, with the exception of more women in group II (61.5% vs 35.8%; P = .003). Based on preprocedure duplex, there was no difference in the vein size (4.4 ± 1.2 vs 3.9 ± 1.4 mm; P = .122) and volume flow (723 ± 450 vs 492 ± 370 mL/min; P = .079) between groups. However, higher rate of AVF stenosis was noted in Group II (39.5%) as compared with Group I (17.9%; P = .007). Seventy-nine percent (n = 94) of the AVFs in Group I achieved maturation after the initial BAM as compared with 54.9% (n = 28) in Group II (P = .001). Forty-four percent (n = 23) of patients in Group II required additional procedures to achieve maturation vs 22.3% (n = 27) patients in Group I (P = .001). There was a similar incidence of intraprocedural contrast extravasation and post-procedural hematoma in both groups (10.7% vs 17.3%; P = .23). None of the complications required intervention nor did it impact AVF patency. We demonstrated that utilizing large angioplasty balloons during initial BAM is safe and allows to achieve AVF maturation with fewer number of procedures.

The Impact of Intervention on Arteriovenous Fistula Maturation and Functional Patency in the Hemodialysis Fistula Maturation Study

National initiatives have emphasized the use of arteriovenous fistulas (AVF) for hemodialysis, but this has been associated with high maturation failure rates. This study describes intervention outcomes to facilitate AVF maturation and maintain post-maturation patency among patients enrolled in the Hemodialysis Fistula Maturation study.

Intimal Hyperplasia and Arteriovenous Fistula Failure: Looking Beyond Size Differences.

The development of venous intimal hyperplasia (IH) has been historically associated with failure of arteriovenous fistulas (AVF) used for hemodialysis. This long-standing assumption, based on histological observations, has been recently challenged by clinical studies indicating that the size of the intima by itself is not enough to explain stenosis or AVF maturation failure. Irrespective of this lack of association, IH is present in most native veins and fistulas, is prominent in many cases, and suggests a role in the vein that may not be reflected by its dimensions. Therefore, the contribution of IH to AVF dysfunction remains controversial. Using only clinical data and avoiding extrapolations from animal models, we critically discuss the biological significance of IH in vein remodeling, vascular access function, and the response of the venous wall to repeated trauma in hemodialysis patients. We address questions and pose new ones such as: What are the factors that contribute to IH in pre-access veins and AVFs? Do cellular phenotypes and composition of the intima influence AVF function? Are there protective roles of the venous intima? This review explores these possibilities, with hopes of rekindling a critical discussion about venous IH that goes beyond thickness and AVF outcomes.

Ultrasound evaluation of access complications: Thrombosis, aneurysms, pseudoaneurysms and infections.

Arteriovenous fistula (AVF) complications are classified based on fistula outcomes. This review aims to update colour Doppler (CD) and pulse wave Doppler (PWD) roles in managing early and late complications of the native and prosthetic AVF. Vascular access (VA) failure occurs because inflow or outflow stenosis activates Wirchow’s triad inducing thrombosis. Therefore, the diagnosis of the tributary artery and outgoing vein stenosis will be the first topic considered. Post-implantation complications occur from the inability to achieve AVF maturation and dialysis suitability due to inflow/outflow stenosis. Late stenosis is usually a sequence of early defects repaired to maintain patency. Less frequently, in the mature AVF or graft, complications are acquired ‘de novo’. They derive either from incorrect management of vascular access (haematoma, pseudoaneurysm, prosthesis infection) or wall pathologies (aneurysm, myxoid valve degeneration, kinking, coiling, abnormal dilation from defects of elastic structures). High-resolution transducers (10–20 MHz) allow the characterization of the wall damage, haemodynamic dysfunctions, early and late complications even if phlebography remains the gold standard for the diagnosis for its sensitivity and specificity.

Sex Differences in Inflammation During Venous Remodeling of Arteriovenous Fistulae.

Vascular disorders frequently have differing clinical presentations among women and men. Sex differences exist in vascular access for hemodialysis; women have reduced rates of arteriovenous fistula (AVF) maturation as well as fistula utilization compared with men. Inflammation is increasingly implicated in both clinical studies and animal models as a potent mechanism driving AVF maturation, especially in vessel dilation and wall thickening, that allows venous remodeling to the fistula environment to support hemodialysis. Sex differences have long been recognized in arterial remodeling and diseases, with men having increased cardiovascular events compared with pre-menopausal women. Many of these arterial diseases are driven by inflammation that is similar to the inflammation during AVF maturation. Improved understanding of sex differences in inflammation during vascular remodeling may suggest sex-specific vascular therapies to improve AVF success.

A UK Expert Consensus Approach for Managing Symptomatic Arteriovenous Fistula (AVF) Stenosis in Haemodialysis Patients.

Stenoses in mature arteriovenous fistulas (AVFs) are common and can negatively impact on the quality of haemodialysis, the longevity of the AVF and lead to debilitating symptoms. Multiple treatment options exist; however, management can vary between different centres. We aimed to establish multidisciplinary consensus on the optimal stepwise application of interventions based on evidence and consensus. A modified Delphi process was conducted with 13 participants from hospitals across the UK, all of whom have high-volume dialysis access practice. The usual intervention to rectify de novo stenoses of mature AVFs is fistuloplasty, although surgery for inflow segment stenoses is also clinically acceptable. Appropriate first-line interventions include plain old balloon angioplasty or high-pressure balloon angioplasty; if these fail during the fistuloplasty, consider upsizing the balloon, prolonged balloon inflation or using alternative interventions, such as cutting or scoring balloons and ultra-high-pressure balloons. Alternative or subsequent interventions vary by anatomical site and may require additional multidisciplinary team input. For a stenoses recurring between 3 and 12months, it is appropriate to consider interventions used de novo, but with a lower threshold for using drug-coated balloons (DCBs) in all regions and for using stent grafts in all regions but inflow segment. Recurrence after 12months should be treated as a de novo lesion, with DCBs considered if they have been used successfully during previous interventions. These recommendations aim to provide a practical guide to multidisciplinary teams in order to optimise the use of multiple interventions for rectifying AVF stenoses and provide unified evidence-based practice guidelines.

Curcumin anti-inflammatory and antitumorigenic effect on arteriovenous fistula maturation in patient with end-stage renal disease with diabetes mellitus

The primary clinical problem of arteriovenous fistula (AVF) is the high maturation failure rate. Curcumin shows anti-inflammatory, antioxidant, antitumorigenic, and antiproliferative effects that may contribute to AVF maturation. This study investigated the effectiveness of curcumin and acetylsalicylic acid on anti-inflammatory and antitumorigenic effects on AVF maturation in patients with End-Stage Renal Disease (ESRD) with diabetes mellitus (DM). The present study is a single-blinded, randomized controlled trial consisting of curcumin, acetylsalicylic acid, or placebo intervention for eight weeks. A total of 67 participants completed the intervention. There was a higher level of nitric oxide (NO) between the curcumin and placebo four weeks (92.58±24.70 vs 75.67±16.50 µmol/L, adjusted p = 0.038) and eight weeks (95.27±28.77 vs 76.66±23.24 µmol/L, adjusted p &lt;0.05) postoperatively. Higher-level of NO between acetylsalicylic acid and placebo (93.65±24.65 vs 75.67±16.50 µmol/L, adjusted p = 0.031) four weeks postoperatively. Curcumin increases NO after four and eight weeks and lowers MMP-9 four weeks after AVF operation. Acetylsalicylic acid increases NO four weeks after AVF surgery on ESRD patients with DM.

Oversized balloon angioplasty for endovascular maturation of arteriovenous fistulae to accelerate cannulation and to decrease the duration of catheter use.

The functional autologous arteriovenous fistula is considered the best vascular access for patients on hemodialysis. Some fistulae exhibit maturation problems after creation and do not reach adequate vessel diameter and flow in dialysis. The aim of this study was to describe our technique of oversized balloon angioplasty for assisted maturation of arteriovenous fistulae to accelerate the cannulation and to decrease the time of catheter use and its outcome. A retrospective analysis of balloon-assisted procedures for maturation failure was performed in a single center between October 2011 and January 2019. Patients underwent imaging procedures to identify stenosis, followed by angioplasty using oversized high-pressure balloons from the anastomosis to the deep venous outflow tract. The flow volume, time interval of use of the fistula and removal of the catheter, patency rates, and complications rates were evaluated. Seventy-eight patients underwent 124 balloon angioplasty procedures. Technical and clinical success was achieved in 91% of the cases. In patients in whom maturation was successful, the fistula was cannulated in a mean time of 5 days after the procedure (range, 1-20 days). On average, catheter removal was performed 14 days (range, 5-33 days) after the maturation procedure. The mean flow volume in the fistula before the procedure was 276 ml/min (range, 122-488 ml/min) and 24 h after the maturation was 1014 ml/min (range, 760-1800 ml/min).The primary patency rate at 3, 6, and 12 months was 87.3%, 66.2%, and 50.7%, respectively. Assisted primary patency was 100% at 3 months, 92.9% at 6 months, and 90.0% at 12 months. Minor complications occurred in 18% of cases, and major complications in 4.8%. The oversized balloon-assisted arteriovenous fistula maturation technique is safe and effective, allowing the cannulation of the fistulae a few hours or days after the procedure and decreasing the time of catheter use.

Intervention with selution SLR™ Agent Balloon for Endovascular Latent Limus therapy for failing AV Fistulas (ISABELLA) Trial: Protocol for a pilot clinical study and pre-clinical results.

The aim of this pilot clinical study is to evaluate the safety and efficacy of the Selution Sustained Limus Release (SLR)™ sirolimus-coated balloon (M.A. MedAlliance SA, Nyon, Switzerland) for improving the patency of failing arterio-venous fistulas (AVF) in hemodialysis patients. We also present herein a pre-clinical pharmacokinetic and safety evaluation of Selution™ to justify its first use in hemodialysis patients for endovascular access salvage. This is an investigator-initiated prospective single-center, non-blinded single-arm trial. Forty patients with clinically significant de novo or recurrent stenoses in a mature AVF circuit will be recruited. All stenotic lesions will be prepared with high pressure non-compliant conventional balloon angioplasty (CBA) prior to deployment of the Sustained-Release Selution™ sirolimus drug-eluting balloon. The primary efficacy endpoint is 6-month target lesion primary patency and the primary safety endpoint is freedom from localized or systemic serious adverse events through 30 days. Secondary endpoints of interest include technical and clinical success rates and circuit access patency at 3 and 6 months. Follow-up will occur for 2 years for those patients whose AVFs remain patent. Pharmacokinetic and histological animal safety studies performed with the Selution™ coating formulation showed prolonged arterial tissue retention of sirolimus with therapeutic levels up to 60 days and non-toxic and rapidly declining blood levels. Histological results in animal models demonstrated safety, freedom from intraluminal thrombus, reduction in restenosis by sirolimus elution compared to CBA, and no evidence of embolic phenomena indicative of adverse particulate effects. Long release sirolimus coated balloons may serve as a promising novel alternative therapy to paclitaxel-based technology for treating conduit stenosis secondary to neointimal hyperplasia. Pre-clinical pharmacokinetic and histological animal data are encouraging and provide suggestion of safety and efficacy in this setting. This single-center trial will provide a first step toward demonstration of efficacy and safety of this device for treatment of stenotic fistulas.

The intraoperative intravascular lithotripsy to recruit a calcified radial artery for creating a distal radio-cephalic fistula.

Guidelines for vascular access recommend that the distal autogenous arteriovenous fistula (AVF) should be the first choice-access procedure for patients starting dialysis. Arteriosclerosis of radial artery may cause early failure, as well as failure of maturation of distal arteriovenous fistulas. To increase the incidence of distal AVFs, our team, specialized in vascular access surgery from 2004 onwards, has introduced Intraoperative Transluminal Angioplasty (ITA) under ultrasound (UG) or fluoroscopic guidance, to recruit inadequate arterials for creating distal fistulas. Intravascular lithotripsy (IL) is a novel approach to treat luminal and medial calcifications in patients with peripheral arterial disease and coronary disease. We believe that intraoperative IL may be an opportunity to recruit calcified radial arteries for creating distal radio-cephalic fistulas. Purpose of this study is to describe the intraoperative IL technical applied in our clinical experience. A 37-year-old diabetic patient with distal radio-cephalic fistula was recruited for the first IL experience. One year ago, a wrist radio-cephalic fistula was created in the right upper limb, with intraoperative UG radial artery angioplasty for extensive calcifications. The fistula was functioning but showed a delay in maturation. An angioplasty was unsuccessfully attempted to facilitate the maturation. Subsequently, a surgical revision of the fistula was performed, creating a new anastomosis immediately upstream of the previous one by performing an intraoperative IL UG of the radial artery. The fistula was immediately well functioning, and was cannulated with two needles after 1 month. It is currently being used with intradialytic adequate blood flow. The positive outcome of the case described in this paper, even if only anecdotal, could act as a trigger for further experiences with IL.

Quantifying The Costs of Creating and Maintaining Hemodialysis Access in An All-Payer Rate-Controlled Health System

The creation and maintenance of durable hemodialysis access is critically important for reducing patient morbidity and controlling overall costs within health systems. Our objective was to quantify the costs associated with hemodialysis access creation and its maintenance over time within a rate-controlled health system where charges equate to payments. The Maryland Health Services Cost Review Commission administrative claims database was used to identify patients who underwent first-time access creation from 2012-2020. Patients were identified using CPT codes for access creation, and costs were accrued for the initial encounter and all subsequent outpatient access-related encounters. T-tests and Wilcoxon tests were used to compare reinterventions and access-related costs ($USD) between arteriovenous fistulae (AVF) and arteriovenous grafts (AVG). Multivariable modeling was used to quantify the association of access type with charge variation. Overall, 12,716 patients underwent first-time access creation (69.3% AVF vs. 30.7% AVG). There was no difference in freedom from reintervention between the two access types at any point following creation (HR: 1.03, 95%CI: 0.97-1.10); however, AVF were associated with a lower number of cumulative reinterventions (1.50 vs. 2.24) compared to AVG (P<0.0001). AVF was associated with lower overall costs in the year of creation ($9,388 vs. $13,539, P<0.0001), a difference that remained significant over the subsequent 3 years. The lower costs associated with AVF were present both in the costs associated with creation and subsequent maintenance. On multivariable analysis, AVF was associated with a $3,557 reduction in total access-related costs versus AVG (95%CI -$3828, -3287). AVF require fewer interventions and are associated with lower costs at placement and over the first three years of maintenance compared to AVG. The use of AVF for first-time hemodialysis access represents an opportunity for healthcare savings in appropriately selected patients with a high preoperative likelihood of AVF maturation.

Patency and Efficacy of Anatomical Snuffbox Arteriovenous Fistula Compared with Wrist Fistula in Patients with End-Stage Renal Disease

Highlights Abstract Introduction: Snuffbox arteriovenous fistula (AVF) is one of the most common vascular accesses for hemodialysis. Despite all the advantages, it is not usually considered the first choice of treatment. This could be primarily due to difficulty in its technical procedure and a higher probability of failure than other sites such as cubital. Therefore, the present study aimed at comparing the efficacy and patency rate between the snuffbox and the wrist AVF. Methods: Seventy-eight patients with end-stage renal disease were enrolled in this study. They were randomly assigned into the snuffbox and the wrist groups. Each participant had an appropriate vein at the time of examination and was eligible for distal AVF creation. The procedure was conducted under local anesthesia, and arteriovenous anastomosis was done in an end-to-side configuration. AVF maturation was defined by initiation of successful dialysis through the AVF 8–10 weeks postoperatively. Results: The results showed that 61% of snuffbox AVFs and 65% of wrist AVFs became matured and were used for further dialysis. Diabetes and female sex had negative impacts on AVF patency. In addition, no significant relationship was found between the patency rate and demographic as well as clinical variables such as age, hypertension, and duration of the previous dialysis. Conclusions: No significant differences were found in the maturation and patency rate between the wrist and the snuffbox AVFs. Therefore, the snuffbox fistula is recommended in the first step, as there would be a possibility for re-creation on the ipsilateral wrist once the AVF fails.

MO776THE USE OF HAND GRIP DEVICE IN ELDERLY PATIENTS ON ARTERIOVENOUS FISTULA MATURATION PROCESS

Abstract Introduction The indication of creation arteriovenous fistula(AVF) may be controversial in elderly population with advanced chronic kidney disease (CKD). Postoperative exercises improve maturation. However, sometimes these exercises could be difficult to perform in the elderly CKD patients. The hand grip device is easy to use, inexpensive and able to increase the muscles of the hand and foream. Nevertheless, scarce scientific evidence has been reported about the role of hand grip device on AVF maturation process in elderly population. Objectives To evaluate the efficacy of a hand grip training program on AVF maturation in our patients older than 75 years old with stages 5-5D CKD. Methodology A 15 months prospective study. After surgery, all patients were randomized to hand grip group (HG) or control group (CG). HG performed a training program using a hand grip device. CO received usual care. Demographics data, upper limb muscle strength (ULMS), Doppler ultrasound (DUS), measurements (outflow vein (OV) diameter and humeral artery blood flow rate (BFR), DUS and clinical AVF maturation as well as VA related complications (hematoma, stenosis, thrombosis, pseudoaneurysm, aneurysm) were assessed at 4 and 8 weeks postoperatively. Results 29 patients. 16 HG, 13 CO. 69% men. Mean age 80,5±2,9 years. 41,4% Radiocephalic AVF. Demographic data, ULMS and DUS measurement at baseline were similar. A significant increase was observed in ULMS only in HG at the end of study (18,8±6,5 vs 21,3±7,1Kg, p=0,005). DUS measurements statistically increased for both groups (OV diameter: CG 2,9 ± 0,6 vs. 5,8 ± 1,4mm; HG 2,9 ± 0,8 vs. 7,2 ± 2,2 mm; humeral artery BFR: CG 132,9± 30,3 vs. 1310,2 ± 691,8ml/min; HG 128,1± 28,9 vs. 1530,7 ± 708,9 ml/min) at the end of study. HG group obtained highest clinical (CG 21,4% vs HG 78,6%;p=0,018) and DUS maturation (CG 27,8% vs HG 72,2%; p=0,011) at 4 weeks and highest clinical (CG 20% vs HG 80%;p=0,007) and DUS maturation (CG 25% vs HG 75%; p=0,002) at 8 weeks, significantly. Despite no significant differences, the number of complications was lower in the HG, mainly significant stenosis (CG 60% vs HG 40%; p=0,428). Conclusions The hand grip device is a useful, safety and easy to use training device to improve the AVF maturation in elderly patients. This device results a novel therapeutic option for the AVF maturation in elderly patients. Further studies are required to support these outcomes in this population.

MO763THE VON WILLEBRAND FACTOR IS A KEY PLAYER IN ARTERIOVENOUS FISTULA MATURATION*

Abstract Background and Aims Low arteriovenous fistula (AVF) maturation rate remains a bottleneck in creating a long lasting lifeline to hemodialysis. AVF maturation is determined by the intricate balance between outward remodeling (OR) and formation of intimal hyperplasia (IH), during which vascular smooth muscle cell (VSMC) proliferation is essential. Recently, the von Willebrand Factor (VWF) has been shown to induce VSMC proliferation in vitro and in vivo. In this study we investigate the role of VWF on VSMC proliferation and AVF functionality to gain a better understanding of the relationship between the two latter processes. Method AVFs were created in wild-type (WT) and VWF (-/-) deficient (B6.129S2-Vwf tm1Wgr) mice using the external jugular vein and the common carotid artery (CCA). Mean velocity and diameter of the CCA was measured at baseline before surgery, t=0 immediately post-surgery, t=7 and t=14 using ultrasonography to determine flow volume (mL/s). The mice were sacrificed at t=14, AVFs were collected and OR and IH were analyzed using Weigert’s elastin and aSMA staining, using the Mann-Whitney test. To study VSMC proliferation in vitro, VSMCs were isolated from vena cava explants. VSMCs from VWF -/- mice were cultured with 10% VWF -/- plasma with or without addition of VWF (Wilfactin). Proliferation was measured after 40 hours. Humane patient-matched samples were obtained during two stage brachio-basalic AVF surgery: the native veins at creation and venous AVF samples at transposition. Maturation was defined as a luminal AVF diameter of &amp;gt; 6 mm. Samples were stained for VWF and aSMA. Positively stained tissue in the medial layer was quantified using Histoquant and analyzed with the Wilcoxon signed-rank test. Results WT mice showed better outcomes in AVF functionality. Whereas blood flow did not increase in VWF deficient mice over two weeks after AVF-creation, WT mice showed a steady increase in flow rate from t=0 to t=7 (1.97 fold) and t=14 (3.0 fold) . At 14 days, VWF -/- mice showed significantly reduced OR compared to WT mice, with a 1.46 fold smaller venous perimeter (p=0.008). Formation of IH was also significantly reduced in VWF -/- mice (9.58 fold change, p = 0,0001), with a non-significant 1.42 fold difference in luminal area. Lastly, an 8.05 fold decrease was observed in aSMA+ cells in the IH of VWF -/-mice (p = 0.0002). In vitro, addition of VWF caused an 1.5 fold increase in proliferation compared to VWF deficient VSMCs cultured without VWF (p=0.016). As for chronic kidney disease (CKD) patients, our study showed significant wall thickening and increase in aSMA+ tissue only in matured AVFs. There was significant upregulation of VWF+ tissue in the media from native veins to venous AVF samples, with 183% in failed AVFs (p= 0.026) and 425% in matured AVFs (p= 0.013). Matured AVFs had a 4.6 fold increase in VWF+ area in the medial layer compared to failed AVFs (p= 0.033). Conclusion Our study demonstrates VWF as an inducer of VSMC proliferation and thereby both OR and IH. Secondly, we show that VWF is essential for AVF maturation and that enhanced expression in the media coincides with AVF maturation in CKD patients.