Primary Arteriovenous Fistula Research Articles

Vascular Surgery Procedures Performed By Residents. A Narrative Review On The Impact In 30-Day Outcomes.

Worldwide, there is an increase in scrutiny after surgical treatment of a vast array of pathologies. Doing so, a large body of evidence clearly supports centralisation, such as teaching hospitals, where a larger caseload enables optimal outcomes. These institutions have a strong presence of surgical residents seeking training in both technical and non-technical skills. Inevitably, as part of training, they will be involved in the surgical treatment of those patients, even as the primary operator. We sought to investigate the impact of trainee performed procedures in outcomes of common vascular procedures of different technical complexity. A non-systematic MEDLINE and Scopus databases review on the outcomes of resident performed common vascular procedures was performed. Specific evidence in many procedures (venous disease, aortic aneurysms, peripheral artery disease) is lacking. After carotid endarterectomy (CEA), resident performed procedures seem to have similar cranial nerve palsy and stroke when compared to expert surgeons. Generally, resident-performed primary radiocephalic and elbow arteriovenous fistula (AVF) presents similar primary and secondary patency. As with CEA, AVF procedures performed by residents took longer. On aortic aneurysms, although no specific comparison has been performed, resident involvement (irrespective of surgeon or assistant) in these procedures does not seem associated with increased adverse events. In most vascular surgery procedures, little is known about resident performance and their impact on outcomes. Notwithstanding, resident-performed CEA and primary AVF seem free of major compromise to patients. Further research is warranted to clarify this topic.

Pathohistomorphometric and Immuno-Histologic Changes in Early Arteriovenous Fistula Failure in Patients with Chronic Kidney Disease.

Hemodialysis is a prevalent treatment for the end-stage chronic kidney disease (CKD) worldwide. The primary arteriovenous fistula (AVF), widely considered the optimal hemodialysis access method, fails to mature in up to two-thirds of the cases. The etiology of the early AVF failure, defined as thrombosis or inability to use within three months post-creation remains less understood, and is influenced by various factors including patient demographics, surgical techniques, and genetic predispositions. Neointimal hyperplasia is a primary histological finding in stenotic lesions leading to the AVF failure. However, there are insufficient data on the cellular phenotypes and the impact of the preexisting CKD-related factors. This study aims to investigate the histological, morphometric, and immunohistochemical alterations in the fistula vein, pre-, peri-, and post-early failure. Eighty-nine stage 4-5 CKD patients underwent standard preoperative assessment, including the Doppler ultrasound, before a typical radio-cephalic AVF creation. Post-failure, a new AVF was created proximally. The vein specimens were collected during the surgery, processed, and analyzed for morphometric analyses and various cellular markers, including Vimentin, TGF, and Ki 67. The study enrolled 89 CKD patients, analyzing various aspects of their condition and AVF failures. The histomorphometric analysis revealed substantial venous luminal stenosis and varied endothelial changes. The immunohistologic analysis showed differential marker expressions pre- and post-AVF creation. This study highlights the complexity of the early AVF failures in CKD patients. The medial hypertrophy emerged as a significant preexisting lesion, while the postoperative analyses indicated a shift towards neointimal hyperplasia. The research underscores the nuanced interplay of vascular remodeling, endothelial damage, and cellular proliferation in the AVF outcomes.

#1335 Distal radio-cephalic arteriovenous fistula survival: comorbid conditions and long-term surveillance in hemodialysis

Abstract Background and Aims With a low incidence of infection and distal ischemia, the distal radio-cephalic arteriovenous fistula (dRCF) is the reference access for hemodialysis (HD). Smaller venous diameter and obesity have been associated with poor distal arteriovenous fistula (AVF) outcomes in some studies. On the other hand, HD patients often suffer from multiple co-morbidities, resulting in an increased number of complications. The impact of all these factors on vascular access survival has not been entirely characterized. We evaluated long-term follow-up demographic and clinical data from a cohort of patients in relation to primary and secondary dRCF survival. Method The study included prevalent patients who had been receiving hemodialysis for at least 6 months at the same reference hospital. From 2008 to 2023, we retrospectively collected dRCF for HD performed by a single reference surgical team. All dRCF could be confirmed to be clinically useful for dialysis (i.e., functional patency). Socio-demographic data were collected. Our medical team (nephrologist and radiologist) periodically performs a physical examination and duplex ultrasound to identify physical signs of possible complications, understand the underlying cause and plan treatment in advance. The time to first repair is termed primary AVF survival, while secondary survival is the time after first repair. Primary and secondary survival analysis was performed using the Kaplan-Meier method. Results Of 253 prevalent patients receiving HD, 82.2% had an AVF. The mean HD vintage was 61 ± 50 months. HD was started on a planned basis in 61.4% of cases, with AVF being the initial access in 71.7% of cases. We included 145 dRCFs for HD. dRCF was the unique AVF that was placed in 74.5% of the patients. Mean age 69.5 ± 14.5 (years), women 31%, mean BMI 27.3 ± 6.08 kg/m2, non-smokers 46.9%, obesity 37.9%, diabetes mellitus 44.8%, ischemic cardiopathy 20%, peripheric vasculopathy 15.9%. Diabetic nephropathy was the most common cause of chronic kidney disease in our population, accounting for 44.8% of cases. dRCF primary failure was 11.11%, 40% of these patients were over 80 years of age. The dRCF was left-sided in 82.2%. dRCF median survival was 64.5 ± 50.4 months; survival rates at 12, 36 and 60 months were 92%, 67% and 41%, respectively. Primary and secondary dRCF median survival was 33 ± 39 months and 50 ± 45 months, respectively. Primary and secondary survival rates at 12, 36 and 60 months were 60%, 32% and 17% and 84%, 53% and 33%, respectively. With a median survival of 62 ± 44 months, 29.7% of the dRCF did not undergo repair either before or during dialysis. The dRCF requiring percutaneous intervention and/or surgical reanastomosis before dialysis was 16.7%. Factors identified as being associated with lower primary survival were obesity and peripheral vasculopathy (p=0.01 and p=0.001, respectively), as shown in Figs. 1 and 2. The percentage of salvage procedures (percutaneous, surgical or both) in obese was 78,2%; 76,7% involved surgical repair, most of which were lipectomies, superficializations with or without transposition. Although not statistically significant (p=0.056), dRCF secondary survival is decreased in diabetic patients (Fig. 3). No statistical impact was found between age, sex, smoking, or ischemic cardiopathy and either primary or secondary survival. Conclusion Our obese patients on HD are a special population with an increased need for surgical reintervention of dRCF, which impacts primary but not secondary survival. Primary dRCF survival is lower in patients with peripheral vascular disease compared to other comorbidities; however, this vasculopathy is not associated with worse secondary dRCF survival with active follow-up. It is likely that individualized and careful long-term active surveillance was a key aspect in improving the functional patency of dRCF in our patients with multiple comorbidities. Undoubtedly, these issues deserve further prospective investigation.

#858 The efficacy of preoperative ultrasound mapping prior to arteriovenous fistula creation: a meta-analysis and systematic review

Abstract Background and Aims Current literature presents conflicting evidence regarding the benefits of Color Doppler Ultrasound (DUS) in the preoperative vascular mapping of arteriovenous fistula (AVF) for haemodialysis. Thus, we conducted a systematic review and meta-analysis of RCTs to evaluate differences in primary AVF failure between patients randomly assigned to routine preoperatory DUS and those randomly assigned to physical examination assessment alone or combined with DUS when physical examination provides limited information. Method We systematically searched PubMed, Google Scholar, Web of Science, and Scopus databases from their inception to November 30, 2023. The accessible text search terms were: “fistula” AND “arteriovenous” AND “dialysis” OR “haemodialysis” AND “Doppler” OR “ultrasound” OR “ultrasonography” AND “preoperative” OR “perioperative” OR “mapping”. No language restriction was applied. We also reviewed references from original papers and review articles to identify additional suitable studies not covered by our original database searches. Exclusion criteria were: (1) meeting abstracts, case reports, reviews, practice guidelines, case-control or cross-sectional or longitudinal studies; (2) RCTs that did not report any estimates of the outcomes of interest; (3) RCTs conducted in the paediatric population (<18 years of age). Two authors independently extracted data from eligible RCTs. Disagreements at this level were resolved by consensus and a third author if needed. The outcome was categorized into three groups: primary AVF failure within 48 hours, within six weeks or 40 months from the vascular procedure. AVF Failure was defined as intraoperative inadequate vessels, incomplete surgical procedure, absence of thrill, thrombosis detection, AVF unsuitability for cannulation at 90 days, inability to achieve Qb 200-300 ml/min at six months, or lack of maturation at 40 months. Statistical analysis was performed using STATA 17.0 software with the metanalysis package and R (version 4.2.2.) for all statistical analyses. This study was performed according to the updated Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement. Results We included 6 RCTs involving 802 patients. Fig. 1 summarizes the results of the literature search and study selection. Table 1 shows the main clinical characteristics of RCTs. Compared to controls, the use of routine preoperative DUS was associated with a reduction in the risk of AVF failure within 48 hours [5 RCTs; OR 0.27, confidence interval 95% 0.16-0.45 for the common effect model (CEM); OR 0.27, CI 95% 0.16-0.46 for the random effects model (REM), no heterogeneity (I2 = 0%)]; within six weeks [2 RCTs (OR 0.33, CI: 95% 0.18-0.61 for CEM, and OR 0.34, CI 95% 0.18-0.63 for REM with I2 = 0%]; and within 40 months [4 RCTs, OR 0.51, CI 95% 0.35-0.75 for CEM; and OR 0.51, CI 95% 0.35-0.76 for the REM, with I2 = 0%] from surgical intervention (Figs 2–4). Conclusion Routine use of DUS in preoperative vascular mapping improves the survival AVF in the immediate to 40 months post-surgery, compared to relying solely on physical examination or using DUS only in cases of insufficient physical examination.

Staged angioplasty using a full-length balloon catheter to achieve maturation of arteriovenous fistulas.

To evaluate the efficacy of staged full-length balloon-assisted maturation (BAM) for the maturation of arteriovenous fistulas (AVFs) on entire segmental veins, including stenosis, causing primary AVF failure. This study included patients who underwent AVF surgery using an autogenous vein between February 2020 and June 2021 and received staged angioplasty with a full-length balloon catheter. To minimize balloon overlap and the risk of barotrauma to the immature vein, serial-staged upsizing balloon angioplasty with a long balloon catheter covering the entire vein segment was employed approximately 2 weeks apart. Twenty-three patients (mean age, 69.50 years; mean follow-up, 620.62 days) with average diameters of the radial artery and cephalic vein at 2.14 ± 0.5 mm and 2.43 ± 0.5 mm, respectively, were enrolled. In the first procedure, the average AVF diameter and flow were 4.03 ± 0.57 mm and 438.08 ± 220.95 mL/min, respectively, with juxta-anastomotic stenosis (JAS) present in 61.5% of cases. After staged full-length BAM, the average fistula diameter and flow improved to 5.95 ± 0.86 mm and 717.52 ± 305.95 mL/min, respectively. Maturation was achieved in 87% of the cases. No hematomas or ruptures occurred around the arterialized veins. Despite successful maturation and cannulation, 65.2% of the patients required additional percutaneous transluminal angioplasty (PTA) during the follow-up period. The necessity for PTA was determined by the presence of JAS prior to the first staged full-length BAM, with an odds ratio of 11.74 (95% confidence interval: 1.31-104.96, P = 0.03). Staged full-length BAM can be safely used in patients with small veins requiring further maturation. Most patients achieved successful cannulation following maturation without post-procedural complications. Staged full-length BAM is a safe and effective method for enhancing maturation in patients with underdeveloped small veins.

Results of Primary Arteriovenous Fistulas Formation with Different Types of Anastomoses in the Early Postoperative Period in Patients on Programmed Hemodialysis

The study includes the analysis of the results of using the different types of arteriovenous anastomoses in the formation of arteriovenous fistulas and their impact on fistula maturation in the early postoperative period. One of the main aspects of the work is to determine the optimal type of anastomosis to ensure the proper functioning of arteriovenous fistula that is an important element of vascular access in patients on renal replacement therapy. It is important to consider such factors as the diameter of formed arteriovenous fistula, the blood flow velocity through it, the incidence of complications and the duration of its functioning. The study also takes into account the impact of patients’ characteristics, such as age, condition of arteries and veins, as well as general health indicators on the results of surgery. Taking these factors into account allows to identify the groups of patients who can benefit most from a particular type of anastomosis.
 During the sample period, 384 patients with terminal stage of renal failure aged 20 to 84 years undergoing programmed hemodialysis, the native arteriovenous fistula was formed. It was found that 94.01 % of arteriovenous fistulas were successful in the early postoperative period. The average age of these patients was 44.2 years, while unsuccessful cases developed in people with an average age of 66.8 years. It was also found that within an hour after surgery for the formation of an arteriovenous fistula with the type end-to-side anastomosis, its diameter increases from 2.08±0.42 mm to 2.96±1.68 mm, and the blood flow velocity increases from 21.4±7.6 ml/min to 212.4±74.6 ml/min. The risk factor for effective fistula formation, in addition to age, is the diameter of vessels, anatomical features of the venous system, the presence of concomitant pathology (primarily diabetes mellitus).
 The obtained results can serve as a basis for the developing of recommendations for the optimal choice of anastomosis type for certain categories of patients who will undergo renal replacement therapy. The study is aimed at improving the results of surgical treatment and increasing the quality of life of patients with chronic renal failure.

Zic family member 3 attenuates oxidative stress-induced vascular smooth muscle cell apoptosis in patients with chronic kidney disease

Neointimal hyperplasia is reportedly essential for arteriovenous fistulas (AVF) in patients undergoing hemodialysis. Oxidative stress is vital in the progression of uremic venous intimal hyperplasia. Studies have suggested that zinc ions obstruct vascular calcification in patients with chronic kidney disease (CKD). Recent studies have shown that the zinc finger protein, Zic family member 3 (ZIC3), is crucial for the earliest cardiovascular progenitors. ZIC3 mutations are associated with congenital heart disease. However, the mechanism of action of ZIC3 in vascular intimal hyperplasia in CKD remains unelucidated. Venous specimens were collected during primary AVF surgery and traumatic amputation, and serum samples were collected from patients with CKD and healthy controls. Mouse vascular smooth muscle cells (VSMCs) were treated with hydrogen peroxide (H2O2) to clarify the role of ZIC3 in CKD. ZIC3 expression was reduced in the veins of patients with uremia and the serum of those with CKD. Zic3 and Bcl2 levels were significantly decreased in mouse VSMCs treated with H2O2·H2O2 inhibited mouse VSMC activity, upregulated Bax, and cleaved caspase 3 expression. Following Zic3 overexpression, Bcl2 expression level and cell viability were elevated, whereas Bax and cleaved caspase 3 expression levels were downregulated. In contrast, Zic3 knockdown yielded the opposite results. Therefore, ZIC3 could be a new therapeutic target in venous neointimal hyperplasia of CKD.

Comparison of Open and Endovascular Aneurysm Repair in Native Arteriovenous Fistulas

Arteriovenous accesses develop aneurysms (FA) during their active use, resulting in pain, erosion, bleeding, and difficulty in cannulation. This study aims to evaluate the outcomes of open and endovascular management of single FA in arteriovenous fistulas (AVF). A retrospective review of all upper extremity primary AVFs over 12years was undertaken at a single center. Patients undergoing elective open and endovascular repair of a single FA were identified. Thirty-day outcomes, cannulation failure, line placement, re-intervention, and functional dialysis (continuous hemodialysis) for 3 consecutive months were examined. Three hundred and seventy nine patients presented with a single FA that met the requirements for intervention: 126 (33%) underwent endovascular repair, and the remainder 253 (67%) underwent open repair. Preoperative fistulogram identified anatomically significant issues in 91% of the cases, and these were treated by balloon angioplasty: 10% within the fistula tract, 44% within the outflow tract, and 47% in the central veins. In open repair, 57% underwent plication, 35% underwent resection and re-anastomosis, and the remainder (8%) underwent interposition grafting. In endovascular repair, successful placement of a stent was achieved in all cases with 1±2 (mean±standard deviation [SD]) covered stents (diameter: 6 -8 mm) placed, achieving successful exclusion of the FA. The combination of early thrombosis and cannulation failures led to the greater need for a tunneled central line in endovascular repair (6.5% vs. 2.4%; endovascular versus open repair; P=0.04). As a result, the mean time for establishing renewed access in the index AVF was significantly higher in endovascular repair (2±3 vs. 2±2weeks, mean±SD; endovascular open repair versus open repair; P=0.001). In follow-up, there were more secondary interventions per year in the endovascular compared to open repair groups (3.1 vs. 1.4 secondary interventions per year; endovascular versus open repair; P=0.04). Median functional dialysis durations were superior in the open repair (48±6%, mean + standard error) compared to the endovascular repair at 5years. (26±7%; P=0.03). Open repair results in a more rapid return to access use, lower need for a tunneled central line, lower secondary re-intervention rates, and superior functional dialysis durations compared to endovascular repair. Open FA repair should be considered for symptomatic single FA repairs before endovascular FA repair.

Slowly moving the needle away from Fistula First

ObjectiveIn 2019, the management of end-stage kidney disease (ESKD) shifted away from “Fistula First” (FF) to “ESKD Life-Plan: Patient Life-Plan First then Access Needs.” Indeed, some patients exhibit such excessive comorbidity that even relatively minor vascular surgery may be complicated. The purpose of this study was to retrospectively assess complications and mortality (and delineate operative futility) in patients undergoing arteriovenous fistula (AVF) creation in the FF era. MethodsConsecutive AVFs created in a single institution before 2021 were retrospectively reviewed. Operative futility was defined as never-accessed fistula, no initiation of dialysis, failure of access maturation (despite secondary intervention), hemodialysis access-induced distal ischemia requiring ligation, early loss of secondary patency, and/or patient mortality within the first 6 postoperative months. ResultsA total of 401 AVFs were created including radial-cephalic (44%), brachial-cephalic (41%), and brachial-basilic (15%) constructions. Patients exhibited a mean age of 69 ± 15 years; 63% were male, and most (74%) were already being hemodialyzed at the time of fistula creation. Forty-five patients (11%) suffered a cardiac event, and five patients died (1%) within 90 days of their access surgery. Perioperative cardiac events were significantly more common after age 80 (19% vs 8%; P = .004); age >80 years was an independent predictor of major 90-day complications (odds ratio [OR], 1.88; 95% confidence interval [CI], 1.04-3.39; P = .036) and the sole independent predictor of major morbidity defined as cardiopulmonary complications, stroke, or death within the first year (OR, 2.01; 95% CI, 1.24-3.25; P = .004). Operative futility was encountered in 52% of the cohort (n = 208 patients): 40% (n = 160) of primary AVFs failed to mature despite assistance, 19% (n = 77) had lost secondary patency by 6 months, 13% of patients (n = 53) were never started on dialysis after access creation, 4% (n = 16) were dead by 6 months, 2% of AVFs (n = 10) matured but were never accessed, and 2% (n = 9) required ligation for hemodialysis access-induced distal ischemia. Not surprisingly, the sole independent protector against operative futility was that catheter-based dialysis had been established prior to AVF creation (OR, 0.36; 95% CI, 0.22-0.59; P < .01). ConclusionsApproximately 50% of primary AVF operations performed in the aggressive FF era were deemed futile. Octogenarians were particularly prone to futility and complications during this era. A paradigm shift, from FF to an “ESKD Life-Plan” will, hopefully, more thoughtfully match vascular access strategies to individual patient needs.

Obesity drives secondary procedures to achieve access maturation in end-stage renal disease

BackgroundEstablishing long-term arteriovenous access is an important component in the long-term care of a patient with end-stage renal disease. The increasing frequency of obesity is reported to impact the access management of end-stage renal disease patients. This study aims to evaluate the outcomes of arteriovenous fistulae (AVF) in obese and nonobese patients. MethodsA retrospective review of all patients over ten years with primary autogenous AVF (radiocephalic, brachiocephalic, and brachial-basilic) was undertaken at a single center. Patients were subcategorized by body mass index into nonobese, class I, II, and III obesity. Outcomes of maturation (successful progression to hemodialysis), reintervention, functional dialysis (continuous hemodialysis for 3 consecutive months), and patency were examined. ResultsFrom January 1999 to December 2019, 2311 patients (67% female; mean age, 61 ± 15 years) underwent primary AVF placement (12% radiocephalic, 53% brachiocephalic, and 35% brachial basilic). Forty-one percent were nonobese, 29% had class I obesity, 19% had class II obesity, and 11% had class III obesity. The majority of patients were diabetic and Hispanic. The 30-day major adverse cardiovascular event rate was elevated in class II (0.20%) and class III (0.50%) obesity compared with class I obesity (0.15%) and nonobese (0.05%). The 30-day morbidity rate was higher in all classes of obesity (0.5% vs0.3% vs 0.2% vs 0.05% for class III vs class II vs class I obesity and nonobese, respectively). Early thrombosis was significantly increased in class II (9%) and class III obesity (12%) compared with class I obesity (5%) and nonobese (3%). There was a two-fold increase in procedures to effect maturation in class II (51%) and class III (74%) obesity compared with class I obesity (22%) and nonobese (34%). Secondary patency at 3 years was significantly lower in class III (62 ± 4%) and class II (79 ± 3%) compared with class I obesity (87 ± 2%) and nonobese (93 ± 4%). All classes of obesity required significantly more secondary Interventions per year compared with nonobese (3.9 vs 3.1 vs 2.5 vs 1.4 secondary interventions per year for class III vs class II vs class I obesity and nonobese, respectively). ConclusionsAdvancing obesity class is associated with an increased number of procedures to achieve AVF maturation and is associated with poorer patency and functionality as the category of obesity advances.

#4923 ARTERIOVENOUS FISTULAS AS HEMODIALYSIS ACCESS IN A PEDIATRIC POPULATION – IS YOUNGER AGE A REASON TO MAINTAIN CENTRAL VENOUS CATHETER?

Abstract Background and Aims In the pediatric population, transplantation remains the first-line therapy in patients with end-stage renal disease (ESRD). However, it is not always possible, increasing the need for other kidney replacement therapy (KRT) modalities, and hemodialysis (HD) has been growing as a modality choice in recent years. To provide quality HD treatment, efficient vascular access is mandatory, and the arteriovenous fistula (AVF) is advocated as the best long-term access option. However, its creation is technically challenging, and its development and maintenance are some of the most difficult elements in the pediatric population. In this study, we describe our experience in the utilization of AVFs in children and adolescents on HD. Method We conducted a retrospective study including all the AVFs performed in our center on underage patients between January 2006 and December 2022. We reviewed the medical records, collected data on demographic variables, AVF characteristics, blood test results, and clinical outcomes. Statistical analysis was performed using SPSS software. Results Forty-three AVFs were performed in 32 pediatric patients. The median age at first AVF construction was 13.5 years (min 4.8; max 17.9). The most frequent etiology of ESRD was congenital anomalies of kidney and urinary tract (n = 20, 62.5%) and most patients (n = 24, 75.0%) were already receiving KRT. Median follow-up time was 16.4 months (min 1; max 98.4) and, at the end of the follow-up period, most patients (n = 22, 68.8%) were transplanted. The mortality rate was 6.3% (n = 2). In what concerns to the location of the AVF, radiocephalic was the first choice in 46.9% of the cases (n = 15), accounting for 34.9% of the total AVFs. Brachiocephalic location was used in 34.4% (n = 11) of first fistulas and 6 subsequent accesses, accounting for 39.5% of the total AVFs. The brachiobasilic location was chosen in 18.8% (n = 6) of the first AVFs and 25.6% of the total AVFs. Primary AVF failure occurred in 26.6% (n = 11) cases and, in 4 of these (36.4%), it was possible to successfully use the same location for a second AVF. We observed no statistical association between primary AVF failure dysfunction and gender, age at the construction of the first fistula, AVF location, or dialysis vintage. Platelet-lymphocyte (PLR) and neutrophil-lymphocyte (NLR) ratios also did not differ between groups. Primary and secondary patency rates at one year were, respectively, 62.5% and 93.8%. With respect to total AVF complications, we observed: thrombosis (27.9%), stenosis (18.6%), distal ischemia induced by vascular access (4.7%), and high flow/aneurismatic dilations (18.6%). The presence of complications was statistically related to age (p = 0.046), with more events in older patients at the time of AVF construction. There was no statistical difference between complications’ occurrence and AVF type, sex, gender, PLR, and NLR. Conclusion The utilization of AVF for HD has been growingly recognized as a safe and efficient alternative for the performance of KRT in pediatric patients. Although larger studies are needed, we demonstrate positive results in its usage in a pediatric population, with high primary and secondary patency rates. These outcomes were independent of the AVF location. We also advocate AVF usage in younger patients, as complications were associated with older age. PLR and NLR, which are emerging biomarkers for systemic inflammation, were not associated with AVF dysfunction, aligning with the results of other studies in pediatrics.

#5088 ARTIFICIAL INTELLIGENCE APPLIED TO VASCULAR DOPPLER ULTRASOUND MODELS FOR PREDICTING UNDERDEVELOPMENT OF VASCULAR ACCESS IN NEPHROLOGY

Abstract Background and Aims The vascular access of choice for hemodialysis patients is the arteriovenous fistula (AVF). There is a high rate of early primary failure and loss of primary AVF patency. Monitoring of vascular access is essential for early diagnosis of complications and prolonging survival. Models based on Artificial Intelligence (AI) and Machine Learning (ML) can be used for this. Method Retrospective descriptive study of the Vascular Doppler Ultrasound (VDU) in adults carried out since January 2019 to January 2022 in our AVF follow-up nephrology clinic. We analyze the results and create AI-based AVF underdevelopment prediction models. We included clinical, demographic and ultrasound variables. Patients were undergoing AVF post-surgery follow-up (VDU by protocol at 3-4 weeks after AVF surgery) or were referred to the clinic with signs of AVF dysfunction. The insufficient development of the vascular access is established as an objective variable. SPSS 20 Statistical Package. Automated Learning Analysis (ML) with Orange ML and BigML. Results 243 VDU were performed. Of the total, 139 (57%) were follow-up post-surgical VDU per protocol and 104 (43%) were AVF dysfunction VDU. Using supervised ML Analysis techniques with random sampling of 80% of the instances for Training and 20% for Test, we obtain prediction models for the underdevelopment (UD) attribute of FAV: Decision tree algorithm, Area under the curve (AUC) 89%, Classification accuracy (CA) 90%, Precision 90%. Random Forest Algorithm (RF) (AUC) 95%, (CA) 86%, Accuracy 81%. Near Neighbor Algorithm (K-NN) (AUC) 88%, CA 82%, Accuracy 78%. Convolutional Neural Networks (NNC) (AUC) 82%, CA 74%, Accuracy 60%. Algorithm with unsupervised technique of clustering in k-Means 3 clusters are obtained. The variables that best correlate with the objective variable are access flow, vein diameter, resistance index (RI) proximal, (RI) distal, and diameter of the anastomosis. Conclusion The vascular ultrasound systematized by the nephrologist facilitates the early diagnosis of complications that lead to early intervention. Analysis of the data with techniques (ML) can facilitate early diagnosis AVF poor development requiring close monitoring or intervention. The development of a nephrology clinic for monitoring vascular access could avoid invasive and unnecessary procedures for the patient.

Functional patency rates of arteriovenous fistula of a retrospective cohort study from one of thebiggest centers in Canada.

The main barriers to arterio-venous fistula (AVF) utilization are primary failure, long maturation duration, and low secondary patency rates. In this retrospective cohort study, primary, secondary, functional primary, and functional secondary patency rates were calculated and compared between two age groups (< 75years and > = 75years) and between radiocephalic (RC-) and upper arm (UA-) AVFs, and factors determining the duration of functional secondary patency were evaluated. Between 2016 and 2020,206 predialysis patients whose AVFs had been created previously initiated renal replacement treatment. RC-AVFs comprised 23.3% and were created after favorable analysis of the forearm vasculature. Overall, the primary failure rate was 8.3, and 84.7% started hemodialysis with a functioning AVF. Functional secondary patency rates of primary AVFs were better with RC-AVFs [1,3 and 5year rates of 95.8, 81.9 and 81.9% versus 83.4, 71.8 and 59.2% for UA-AVFs (log rankp: 0.041)]. There was no difference between the two age groups for any of the AVF outcomes assessed. Among patients whose AVF was abandoned, 40.3% had gone on to have a second fistula created. This was significantly less likely in the older group (p < 0.01). (1) UA-AVFs were placed more commonly than RC-AVFs; (2) a selection bias existed whereby RC-AVFs were only created after favorable forearm vasculature was demonstrated or suspected; (3) superior functional secondary patency rates were observed with RC-AV's, perhaps stemming from this selection bias; (4) the elderly were more likely to have only one AVF creation attempt.

Arterial Diameter and Percentage of Monocytes are Sex-Dependent Predictors of Early Arteriovenous Fistula Maturation

Arteriovenous fistulae mature less frequently in women than in men, leading to inferior patency and decreased fistula utilization in women. We hypothesized that both anatomic and physiologic sex differences explain reduced maturation. The electronic medical records of patients who had a primary arteriovenous fistula created from 2016 to 2021 at a single center were reviewed; sample size was determined using a power calculation. Postoperative ultrasound and laboratory tests were obtained at least 4weeks after fistula creation. Primary unassisted fistula maturation was determined up to 4years postprocedure. A total of 28 women and 28 men with a brachial-cephalic fistula were analyzed. The inflow brachial artery diameter was smaller in women than in men, both preoperatively (4.2±0.9 vs. 4.9±1.0mm, P=0.008) and postoperatively (4.8±0.8 vs. 5.3±0.9mm, P=0.039). Despite similar preoperative brachial artery peak systolic velocity, women had significantly lower postoperative arterial velocity (P=0.027). Fistula flow was reduced in women, particularly in the midhumerus (747.0±570.4 vs. 1,117.1±471.3cc/min, P=0.003). Percentages of neutrophils and lymphocytes were similar among women and men 6weeks after fistula creation. However, women had reduced monocytes (8.5±2.0 vs. 10.0±2.6%, P=0.0168). Among 28 men, 24 of 28 (85.7%) achieved unassisted maturation, whereas only 15 of 28 (53.6%) women had fistulae that matured without intervention. Secondary analysis using logistic regression suggested that postoperative arterial diameter was associated with maturation in men, while postoperative monocyte percentage was associated with maturation in women. Sex differences during arteriovenous fistula maturation are present in arterial diameter and velocity, suggesting that both anatomic and physiologic differences in arterial inflow contribute to sex differences in fistula maturation. In men, postoperative arterial diameter is correlated with maturation, whereas in women, the significantly lower proportion of circulating monocytes suggests a role for the immune response in fistula maturation.

Arteriovenous fistula aneurysmorrhaphy is associated with improved patency and decreased vascular access abandonment

BackgroundUpper extremity hemodialysis arteriovenous fistulas (AVFs) can become aneurysmal over time due to repeated cannulation and/or outflow steno-occlusive disease. The optimal surgical management of aneurysmal AVFs (aneurysmorrhaphy vs interposition graft) has remained unclear. MethodsWe performed a retrospective review in which current procedural terminology codes were used to screen for patients who had undergone surgical treatment of aneurysmal AVFs between 2016 and 2021 at a single hospital system. The patients were included after a review of the operative reports. The cases were divided by surgical procedure (aneurysmorrhaphy vs interposition graft placement). The patients who had undergone primary AVF ligation or other types of repair were excluded. The primary outcomes were primary assisted and secondary patency, and the secondary outcome was dialysis access abandonment. Multivariable Cox proportional hazards regression was used to test the association between the type of AVF aneurysm repair and the primary and secondary outcomes. ResultsFrom 2016 to 2021, 6951 patients had undergone 16,190 dialysis access procedures. Of these procedures, 381 (2.4%) were related to surgical treatment of an aneurysmal AVF. We excluded 58 primary AVF ligation cases and 20 cases involving other types of repair, leaving 303 cases for analysis. These were divided into two groups: aneurysmorrhaphy (n = 123; 41%) and interposition graft (n = 180; 59%). No differences were found between the groups in male gender (68% vs 63%), hypertension (98% vs 98%), or central stenosis (14% vs 22%). The patients who had undergone aneurysmorrhaphy were younger (median age, 54 years vs 59 years); had had a lower rate of diabetes (41% vs 59%), coronary artery disease (41% vs 58%), and congestive heart failure (41% vs 55%); and were less likely to have undergone upper arm access (72% vs 92%). The median follow-up was 11.1 months (interquartile range, 3.6-25.2 months). No differences were found in the incidence of 30-day wound complications (1% vs 3%) or surgical site infections (4% vs 6%). On multivariable Cox regression, interposition graft placement was associated with the loss of primary assisted patency (adjusted hazard ratio [aHR], 2.42; 95% confidence interval [CI], 1.18-4.95), loss of secondary patency (aHR, 3.10; 95% CI, 1.21-7.94), and abandonment of dialysis access (aHR, 3.07; 95% CI, 1.61-5.87; P < .05 for all) at 2 years. ConclusionsAVF aneurysmorrhaphy was associated with improved primary assisted and secondary patency and decreased abandonment of dialysis access. We suggest using aneurysmorrhaphy when AVF aneurysms are indicated for repair. However, individual factors such as patient comorbidities, AVF anatomy, remaining dialysis access options, and patient preference should be considered when planning the surgical approach.

The effect of the location of arteriovenous fistula on the right ventricle in end stage renal disease patients indicated for hemodialysis

Abstract Background End-stage renal disease (ESRD) has significantly increased in developing countries such as Egypt [1]. There are many sites for arteriovenous fistula (AVF) creation. The most common sites for AVF are radio-cephalic AVF (RC-AVF) followed by brachio-cephalic AVF (BC-AVF) [2]. To date, there are no significant studies discussing the possible correlation between the AVF location and abnormalities in the right ventricle (RV) in hemodialysis (HD) patients. Objective To determine the best location for AVF in order to ensure the least possible hazardous side effects of the AVF on the RV. Methods Our study, designed as an interventional study, included 50 ESRD patients referred for primary AVF construction to start HD for the first time. Patients were divided into two groups, 25 patients each. one group underwent a RC-AVF construction and the other had a BC-AVF. We assessed the RV by two dimensional transthoracic echocardiography (2D TTE) twice for each patient, firstly just before the AVF surgery and secondly three months after AVF construction. Results There was a statistically significant difference in between study groups regarding change in RV Tei index (p=0.001) with a decrease in the radial group (Mean ± SD = −0.19±0.2) and an increase in the brachial group (Mean ± SD = 0.02±0.12), and regarding the right ventricular outflow tract proximal diameter (p&amp;lt;0.001) with a decrease in the radial group (Mean ± SD = −2.32±5.49) and a larger increase in the brachial group (Mean ± SD = 2.94±3.14). Changes in the other RV dimensions and functional parameters did not show statistically significant difference. Conclusion After three months follow up, despite the fact that all the RV parameters remained within the normal range, the RV indices with the RC-AVF were associated with either improvement or less decline than with the BC-AVF. Funding Acknowledgement Type of funding sources: None.

Localized Perivascular Therapeutic Approaches to Inhibit Venous Neointimal Hyperplasia in Arteriovenous Fistula Access for Hemodialysis Use.

An arteriovenous fistula (AVF) is the preferred vascular access for chronic hemodialysis, but high failure rates restrict its use. Optimizing patients’ perioperative status and the surgical technique, among other methods for preventing primary AVF failure, continue to fall short in lowering failure rates in clinical practice. One of the predominant causes of AVF failure is neointimal hyperplasia (NIH), a process that results from the synergistic effects of inflammation, hypoxia, and hemodynamic shear stress on vascular tissue. Although several systemic therapies have aimed at suppressing NIH, none has shown a clear benefit towards this goal. Localized therapeutic approaches may improve rates of AVF maturation by providing direct structural and functional support to the maturating fistula, as well as by delivering higher doses of pharmacologic agents while avoiding the adverse effects associated with systemic administration of therapeutic agents. Novel materials—such as polymeric scaffolds and nanoparticles—have enabled the development of different perivascular therapies, such as supportive mechanical devices, targeted drug delivery, and cell-based therapeutics. In this review, we summarize various perivascular therapeutic approaches, available data on their effectiveness, and the outlook for localized therapies targeting NIH in the setting of AVF for hemodialysis use. Highlights: Most systemic therapies do not improve AVF patency outcomes; therefore, localized therapeutic approaches may be beneficial. Locally delivered drugs and medical devices may improve AVF patency outcomes by providing biological and mechanical support. Cell-based therapies have shown promise in suppressing NIH by delivering a more extensive array of bioactive substances in response to the biochemical changes in the AVF microenvironment.

Outcome of Radiocephalic Arteriovenous Fistula Constructed Under Brachial Plexus Block Versus Local Anesthesia: A Randomized Controlled Trial

Backgrounds: Hemodialysis (HD) is the commonest modality of renal replacement therapy (RRT) which needs vascular access. Ideal vascular access should be well functional, durable, stable, and have fewer complications. An arteriovenous fistula (AVF) is the preferred form of vascular access and is recommended by Kidney Disease Improving Global Outcome (KDIGO) guidelines. Most of the AVFs are constructed under local anesthetic infiltration which has a high failure rate which is about 30-40% for radiocephalic arteriovenous fistula (RCAVF). This study aimed to change the anesthetic technique to brachial plexus block (BPB) for RCAVF creation to improve the primary patency rate and reduce early thrombotic complications. Objectives: The objective was to see the effect of brachial plexus block (BPB) on the outcome of AVF creation by primary patency rate, maturation time, primary functional patency rate, and complications. Materials and Method: This was a randomized controlled trial conducted in the Department of Urology, Bangabandhu Sheikh Mujib Medical University, Dhaka from December 2018 to December 2019. A total of 80 patients were selected from the study population according to inclusion and exclusion criteria. Then divided into two groups by simple random sampling. In the group, A RCAVF constructed under BPB, and group B RCAVF was constructed under LA. The standard operation technique of AVF construction was followed. Evaluation of AVFs was done at 3rd POD, 2nd week, 6th week, and 12th weeks to see the functional status and any complications. Doppler US was done at the 6th week routinely. Results: Among these 80 patients 3 patients were lost from the follow-up, two from group A and one from group B. There was no significant difference in age, sex, comorbidities, and HD status between the groups. There was higher primary patency in group A at 3rd POD and 2nd weeks but was not statistically significant. In the 6th week primary patency in group A was 33/38 (86.8%) and in group B 25/39(64.1%), p=0.033. In the 12th week, primary patency and functional primary patency rate were in group A was 33/38 (86.8%) and in group B 25/39(64.1%), p=0.033 and statistically significant. No significant difference in maturation time between the groups. Thrombosis was the most common complication, 14 in group B and 5 in group A. One BPB was failed but there was no significant complication related to BPB. Conclusion: Radiocephalic arteriovenous fistula constructed under brachial plexus block has better primary patency and functional primary patency than local anesthesia at 6th and 12th week. Early thrombotic complications were higher in AVF creation under local anesthetic infiltration. Anaesthesia with BPB can be used for primary radiocephalic AVF construction surgery to improve the outcome of RCAVF fistula and early complications. Bangladesh J. Urol. 2021; 24(2): 129-134

High pulse pressure predicts primary arteriovenous fistula failure within 1 year.

The arteriovenous fistula is the preferred access route for hemodialysis, although its high primary failure rate remains a clinical challenge. Multiple studies have attempted to determine the risk factors for primary arteriovenous fistula failure; however, none have identified pulse pressure as a potential predictive marker. High pulse pressure is a surrogate poor arterial compliance endpoint and leads to inferior cardiovascular outcomes. Our aim was to determine whether elevated pulse pressure indicates poor arteriovenous fistula maturation. We retrospectively reviewed 274 patients who underwent an arteriovenous fistula index operation between September 1, 2018 and May 31, 2019. Demographic, clinical data, and operative parameters were collected and analyzed. The maximum follow-up period was 365 days. Arteriovenous fistula failure was defined as the inability to achieve functional use during the follow-up period. We identified risk factors for arteriovenous fistula failure by performing a multivariate logistic regression analysis using backward elimination procedures. A total of 274 patients were included in the study. The patients' average age was 61.3 ± 14.0 years, approximately half of the patients (n = 161, 58.8%) were male, and the majority had hypertension. At the end of the follow-up period, 68 (24.8%) had arteriovenous fistula failure. The proportion of patients with pulse pressure values of >60 mmHg was significantly higher in the failure group than in the maturation group (66.0% vs 80.9%; p = 0.021). A PP value of >60 mmHg (odds ratio = 2.25; 95% confidence interval = 1.14-4.42; p = 0.019) and coronary artery disease or myocardial infarction (odds ratio = 1.97; 95% confidence interval = 1.01-3.84; p = 0.045) were found to be independent risk factors for primary arteriovenous fistula failure. High pulse pressure is an independent risk factor for primary arteriovenous fistula failure.

Anaesthesia Choice for Creation of Arteriovenous Fistula (ACCess) study protocol : a randomised controlled trial comparing primary unassisted patency at 1 year of primary arteriovenous fistulae created under regional compared to local anaesthesia

IntroductionArteriovenous fistulae (AVF) are the ‘gold standard’ vascular access for haemodialysis. Universal usage is limited, however, by a high early failure rate. Several small, single-centre studies have demonstrated better early...