Arteriovenous Fistula Maturation Research Articles

Triggering receptors expressed on myeloid cells-1 and maturation of arteriovenous fistula

Triggering receptors expressed on myeloid cells-1 and maturation of arteriovenous fistula

Vein distensibility is superior to vein diameter for predicting unassisted maturation of arteriovenous fistulae

BackgroundA mature arteriovenous fistula (AVF) is the preferred hemodialysis access owing to its durability and lower risk of complications. Various factors have been implicated as predictors for maturation, including vein diameter and access type. Vein distensibility, which refers to the ability of the vein to dilate in response to changes in blood flow and pressure, has been proposed as a potential predictor for maturation, but its utility remains poorly studied. MethodsThis is a single-institution retrospective study of AVFs performed under regional anesthesia. Vein distensibility was defined as the absolute and relative difference in target vein diameter (TVD) between the preoperative ultrasound vein mapping performed with tourniquet and a repeat ultrasound examination after a regional block before AVF creation and without a tourniquet. ResultsForty-six patients underwent first-time AVF surgery with distensibility recorded in a prospectively maintained database. The mean initial preoperative TVD was 2.7 mm, and after the block 3.4 mm. The unassisted maturation rate for the entire cohort was 76%. In patients with an absolute change of TVD of <0.5 mm (Δ<0.5), the unassisted maturation rate was 63% (12/19), even though 95% of the group had a preoperative TVD of >3 mm. In those with ≥0.5 mm, the unassisted maturation rate was 85% (23/27; P = .08), even though the preoperative vein map TVD was 2.3 mm and 75% had a vein map TVD of <3 mm. For radiocephalic AVFs (n = 26), the unassisted maturation rate was 75% for Δ<0.5 vs 94% for Δ≥0.5 (P = .16), despite a preoperative vein map TVD of >3 mm in 92% vs 75%, respectively. The receiver operatring characteristic area under the curve for unassisted maturation with a Δ≥0.5 mm was 0.68 (P = .26). ConclusionsQuality in dialysis access surgery requires optimizing the unassisted maturation rate. A physiological measure that accounts for the dynamic process of maturation may be more informative than anatomic measurements alone. The results shown here demonstrate that vein distensibility may be a better predictor than absolute vein diameter on standard vein mapping ultrasound examinations.

Insights into the real-world practice of vascular access care pathways in Italy: data from a national survey.

International guidelines issued recommendations for vascular access (VA) care for hemodialysis, but there are no registry data regarding this topic in Italy. A survey consisting of 17 items was sent to all Italian dialysis wards, via the Italian Society of Nephrology (SIN) website, from April to June 2021.The items were defined,discussedand approved by experts in vascular access management within the Italian Society of Nephrology. A total of 124 dialysis units answered, accounting for 14% of all dialysis units. The survey thus encompasses all regions within the country, with some regional variations in terms of adherence. One hundred twenty-four facilities provided data, regarding 12,276 patients: 61% had an arteriovenous fistula (AVF), 34% had a central venous catheter (CVC), and 5% had an arteriovenous graft (AVG). Among them, two-thirds of the facilitiesreported having a vascular access care pathway, formally standardized in 79% of cases. Forty-six % of centers had a fully equipped vascular access care pathway, encompassing preoperative mapping (80%), vascular access setup (71%), arteriovenous fistula maturation monitoring (76%), first-level (80%) and second-level (78%) monitoring, and surgical and/or endovascular treatment of complications (66%). Vascular access monitoring was computerized in 39% of facilities. First-level monitoring (physical examination) was primarily done by nurses in two-thirds of facilities. Of note, 45% of centers had nurses who were skilled in ultrasound-guided cannulation. Quite surprisingly, facilities with less than 100 patients had a greater prevalence of arteriovenous fistulas than those with more than 100 patients (p = 0.0023). A protocolled vascular access care pathway was associated with a higher likelihood of having an arteriovenous fistula (70% AVF vs 42,1% CVC; p = 0.04). The presence in the facilityof interventional nephrologists or nurses with ultrasound-guided cannulation skills significantly reduced the prevalence of central venous catheters. These survey data further strengthen the need for formal and shared vascular access monitoring protocols.

Type 2 diabetes increase the risk of arteriovenous fistula non-maturation, mediated by postoperative vascular hemodynamics.

The progression of atherosclerosis in small and medium-sized vessels has been associated with Type 2 diabetes (T2D). However, the influence of T2D on postoperative vascular remodeling and arteriovenous fistula (AVF) maturation is inconclusive. Besides, hemodynamic changes of postoperative vessel are also associated with AVF maturation. This study is intended to investigate the link between T2D and the occurrence of AVF non-maturation, as well as to delve into the impact of postoperative vascular hemodynamic parameters in this process. A total of 477 hemodialysis patients, with or without type 2 diabetes, underwent AVF creation at Beijing Haidian Hospital (Haidian Section of Pecking University Third Hospital) from August 2018 to March 2022 were collected, and were followed for 1-5years. Logistic regression was applied to analyze the association of T2D, postoperative vascular hemodynamic parameters with the risk of AVF non-maturation. To verify the stability of the results, the sensitivity analyses were performed using propensity scores to match patients. We further investigated the regulatory role of the postoperative vascular hemodynamics. There were 173 patients with T2D and 304 patients without T2D in this study. The maturation rate in T2D and non-T2D group was 47.977% and 63.816%, respectively. The findings of logistic regression analysis suggested that T2D significantly increased the risk of AVF immaturity [OR 1.716 (1.019-2.890), P = 0.042]. Besides, T2D was associated with the restriction of postoperative vascular hemodynamic parameters changes, including with decreased diameter of forearm cephalic radial artery and dilation rate of radial artery. The result of logistic regression analysis indicated that cephalic vein diameter at 1-month [0.402 (0.237-0.681), P = 0.001] and cephalic vein diameter at 2-month [0.501 (0.355-0.708), P < 0.001] were independently correlated with AVF maturation. Besides, the results of sensitivity analysis were consistent with that of logistic regression analysis. Moreover, the mediating effects of cephalic vein diameter were significant. Our findings discovered that T2D significantly increased the risk of arteriovenous fistula non-maturation, which was mainly mediated by the changes of cephalic vein diameter.

Early Prediction of Native Arteriovenous Fistula for Maturation by Doppler Ultrasound Study

Introduction: There are significant chances of maturation failure in arteriovenous fistulas (AVFs) made for vascular access for hemodialysis. AVFs are usually assessed for maturation 6 weeks after the operation. Significant time is lost for performing a salvage radiological procedure or making an alternative AVF, in case the AVF fails to mature. Materials and Methods: This prospective observational study was conducted to predict the chances of maturation of AVF by Doppler ultrasound (USG) study. One hundred and thirty-seven patients in whom native AVF was made as a vascular access procedure for hemodialysis were included in the study. In five patients, palpable thrill was absent after 48 h of operation and were excluded from the study. The velocity of the blood, diameter of the vessel, and depth of the vessel from the skin were assessed by USG Doppler 3 weeks after the operation and were correlated with AVF maturation. Results: Successful maturation occurred in 114 (86.3%) AVF. The flow rate of the blood and depth of the vein were statistically different in successful and unsuccessful AVF maturation for both the groups of radial artery (RA) and brachial artery (BA) based AVF. For RA AVF, successful maturation was predicted by the flow rate of 539 mL/min (sensitivity 95% and specificity 83%) and 4.2 mm diameter of the vein (sensitivity 93% and specificity 100%). For BA AVF, successful maturation was predicted by the flow rate of 456 mL/min (sensitivity 93% and specificity 100%) and 5.7 mm diameter of the vein (sensitivity 77% and specificity 100%). The measurement of flow and depth at 3 weeks after AVF may predict the maturation of AVF. Conclusion: It will be beneficial to do a USG Doppler study 3 weeks after making AVF, as the measurement of flow may predict the maturation of AVF.

The Predictive Significance of Doppler Parameters on the Arteriovenous Fistula Maturation for Hemodialysis—A Single Center Experience

Background: Doppler ultrasound examination of blood vessels has a significant role in planning and identifying parameters that affect the functioning and maturation of arteriovenous fistula (AVF). Our goal was to determine the predictive parameters of Doppler ultrasound, measured at different time distances, which affect the maturation of AVF for hemodialysis. Materials and Methods: The research was a retrospective cohort study. The criteria for selecting patients in our study was the existence of information on ultrasound examinations of the lumen of blood vessels before the creation of AVF, as well as lumens of fistula conduits and blood flow measurements, at time intervals of 6–8 weeks and 2–4 months, after the creation of AVF, which we recorded in 105 patients. The respondents were divided into two groups: a group of patients with immature, and mature fistulas. Basic demographic data, clinical characteristics of the responders and laboratory parameters were analyzed. Results: By comparing clinical and laboratory parameters between the group of subjects with and without AVF maturation, a statistically significant difference was determined between the lumen of the proximal radial vein (p = 0.008) and the lumen of the distal radial vein (p = 0.001). The diameter of the fistulous veins (p = 0.037), and the blood flow through the AVF 6–8 weeks (p = 0.001) and 2–4 months (p = 0.001) after its creation were statistically significantly higher in subjects with mature fistulas. By univariate regression analysis, brachial vein (p = 0.04), proximal (p = 0.011) and distal radial artery (p = 0.001), fistula vein, after 6–8 weeks (p = 0.002), blood flow through AVF 6–8 weeks (p = 0.001) and 2–4 months (p = 0.001) after AVF creation, are statistically significant parameters. Predictive parameters of AVF maturation are AVF blood flow after 6–8 weeks (p = 0.010) and AVF blood flow after 2–4 months (p = 0.001). Conclusion: Our research confirmed that greater the blood flow through AVF, at time intervals of 6–8 weeks and 2–4 months after creation, the better the maturation.

Controlled Delivery of Rosuvastatin or Rapamycin through Electrospun Bismuth Nanoparticle-Infused Perivascular Wraps Promotes Arteriovenous Fistula Maturation.

In the context of arteriovenous fistula (AVF) failure, local delivery enables the release of higher concentrations of drugs that can suppress neointimal hyperplasia (NIH) while reducing systemic adverse effects. However, the radiolucency of polymeric delivery systems hinders long-term in vivo surveillance of safety and efficacy. We hypothesize that using a radiopaque perivascular wrap to deliver anti-NIH drugs could enhance AVF maturation. Through electrospinning, we fabricated multifunctional perivascular polycaprolactone (PCL) wraps loaded with bismuth nanoparticles (BiNPs) for enhanced radiologic visibility and drugs that can attenuate NIH─rosuvastatin (Rosu) and rapamycin (Rapa). The following groups were tested on the AVFs of a total of 24 Sprague-Dawley rats with induced chronic kidney disease: control (i.e., without wrap), PCL-Bi (i.e., wrap with BiNPs), PCL-Bi-Rosu, and PCL-Bi-Rapa. We found that BiNPs significantly improved the wraps' radiopacity without affecting biocompatibility. The drug release profiles of Rosu (hydrophilic drug) and Rapa (hydrophobic drug) differed significantly. Rosu demonstrated a burst release followed by gradual tapering over 8 weeks, while Rapa demonstrated a gradual release similar to that of the hydrophobic BiNPs. In vivo investigations revealed that both drug-loaded wraps can reduce vascular stenosis on ultrasonography and histomorphometry, as well as reduce [18F]Fluorodeoxyglucose uptake on positron emission tomography. Immunohistochemical studies revealed that PCL-Bi-Rosu primarily attenuated endothelial dysfunction and hypoxia in the neointimal layer, while PCL-Bi-Rapa modulated hypoxia, inflammation, and cellular proliferation across the whole outflow vein. In summary, the controlled delivery of drugs with different properties and mechanisms of action against NIH through a multifunctional, radiopaque perivascular wrap can improve imaging and histologic parameters of AVF maturation.

Heterogeneous gene expression during early arteriovenous fistula remodeling suggests that downregulation of metabolism predicts adaptive venous remodeling

Clinical outcomes of arteriovenous fistulae (AVF) for hemodialysis remain inadequate since biological mechanisms of AVF maturation and failure are still poorly understood. Aortocaval fistula creation (AVF group) or a sham operation (sham group) was performed in C57BL/6 mice. Venous limbs were collected on postoperative day 7 and total RNA was extracted for high throughput RNA sequencing and bioinformatic analysis. Genes in metabolic pathways were significantly downregulated in the AVF, whereas significant sex differences were not detected. Since gene expression patterns among the AVF group were heterogenous, the AVF group was divided into a ‘normal’ AVF (nAVF) group and an ‘outliers’ (OUT) group. The gene expression patterns of the nAVF and OUT groups were consistent with previously published data showing venous adaptive remodeling, whereas enrichment analyses showed significant upregulation of metabolism, inflammation and coagulation in the OUT group compared to the nAVF group, suggesting the heterogeneity during venous remodeling reflects early gene expression changes that may correlate with AVF maturation or failure. Early detection of these processes may be a translational strategy to predict fistula failure and reduce patient morbidity.

Association Between Atherosclerotic Cardiovascular Disease (ASCVD) Risk Score and Arteriovenous Fistula Failure in Patients on Maintenance Hemodialysis.

Arteriovenous fistula (AVF) is the vascular access of choice for hemodialysis in end-stage renal disease (ESRD) patients but has a significant failure rate. Atherosclerotic cardiovascular disease (ASCVD) is a major cause of mortality in ESRD patients. Atherosclerosis of the peripheral vessels may contribute to poor maturation of AVF leading to the exploration of the ASCVD score as a prognostic tool for AVF failure. Thisstudy included 110 hemodialysis patients with AVFsand aimed to examine the association between ASCVD score and AVF failure. Participants were categorized into the presence of vascular access failure (N=12) and absence of vascular access failure (N=98), and demographic and clinical data were collected. Results: The study comprised predominantly male patients (63.6%), with a notable prevalence of hypertension anddiabetes. Twelve patients experienced AVF failure, with pseudoaneurysms and thrombosis being the predominant causes. The ASCVD risk group at intermediate and high stages exhibited a statistically significant risk (relative risk (RR)=1.403; 95% CI, 1.041-1.904) of AVF failure in comparison to the low and borderline ASCVD risk groups.There was no association of age, gender (male and female), body mass index (BMI),serum calcium, serum phosphorus, intact parathyroid hormone (iPTH), and serum albumin with AVF failure. The ASCVD score emerges as a potential prognostic tool to identify dialysis patients at high risk of AVF failure, suggesting avenues for targeted interventions and improved patient care. However, limitations of the ASCVD risk estimator and study limitations, such as small sample size and absence of mortality data, warrant cautious interpretation and necessitate further exploration in larger patient populations.

Challenges of Predicting Arteriovenous Access Survival Prior to Conversion from Catheter

The decision to convert from catheter to arteriovenous access is difficult yet very important. The ability to accurately predict fistula survival prior to surgery would significantly improve the decision making process. Many previously investigated demographic and clinical features have been associated with fistula failure. However, it is not conclusively understood how reliable predictions based on these parameters are at an individual level. The aim of this study was to investigate the probability of arteriovenous fistula maturation and survival after conversion using machine learning workflows. A retrospective cohort study on multicentre data from a large North American dialysis organisation was conducted. The study population comprised 73 031 chronic in centre haemodialysis patients. The dataset included 49 variables including demographic and clinical features. Two distinct feature selection and prediction pipelines were used: LASSO regression and Boruta followed by a random forest classifier. Predictions were facilitated for re-conversion to catheter within one year. Additionally, all cause mortality predictions were conducted to serve as a comparator. In total, 38 151 patients (52.2%) had complete data and made up the main cohort. Sensitivity analyses were conducted in 67 421 patients (92.3%) after eliminating variables with a high proportion of missing data points. Selected features diverged between datasets and workflows. A previously failed arteriovenous access appeared to be the most stable predictor for subsequent failure. Prediction of re-conversion based on the demographic and clinical information resulted in an area under the receiver operating characteristic curve (ROCAUC) between 0.541 and 0.571, whereas models predicting all cause mortality performed considerably better (ROCAUC 0.662 - 0.683). While group level depiction of major adverse outcomes after catheter to arteriovenous fistula or graft conversion is possible using the included variables, patient level predictions are associated with limited performance. Factors during and after fistula creation as well as biomolecular and genetic biomarkers might be more relevant predictors of fistula survival than baseline clinical conditions.

Evaluation of arteriovenous fistula maturation and early prediction of clinical eligibility, using ultrasound: The Fistula Maturation Evaluation (FAME) Study.

The study of time-related alterations of ultrasound-determined parameters during maturation, and the assessment of time to hemodynamic maturation, enabling early prediction of clinical eligibility, of hemodialysis autologous arteriovenous fistulae (AVF). This is an observational, prospective, study of only AVF-eligible patients referred for access creation, from 02/2019 to 02/2022 (ClinicalTrials.gov identifier: NCT0473687). Brachial artery diameter (dBA), access flow volume (FV), non-augmented efferent vein diameter (dEV), resistivity index (RI), and efferent vein total wall thickness (tEV), were assessed by ultrasound. Measurements were conducted daily in the first week and repeated on days 14, 21, 30, 60, and 90, postoperatively. The primary endpoint included the documentation of serial changes of flow and structural parameters related to AVF maturation in the first 90 days of the post-operative period and maturation early prediction. Secondary endpoints included the determination of factors affecting maturation. One hundred one participants (mean age, 67 ± 6 years; 76 males) were enrolled. Average dBA and FV reached maximum on day 60 (5.64 ± 0.85 mm) and 90 (1.172 ± 617 mL/min), respectively. Day 7 values of dBA (5.48 ± 0.73 mm) and FV (1.039 ± 531 mL/min) did not alter significantly during the follow-up period. Parameters indicative of clinical functionality, dEV (5.82 ± 0.90 mm) and tEV (0.493 ± 0.10 mm), reached approximately 90% of maximum (6.66 ± 1.42 mm and 0.526 ± 0.11 mm), by day 14. RI reached minimum on day 30 (0.46 ± 0.09), without significant changes after day 2 (0.48 ± 0.09, p = 0.284). A significant correlation was identified, between day 7 FV and day 60 dEV (r = 0.40, p = 0.0002). A FV cut-off value ⩾657.51 mL/min, on day 7, predicted successful fistula maturation with 85% sensitivity and 100% specificity. Multivariate analysis identified female gender, age >75, diabetes, and wrist access as independent predictors of decreased values of maturation parameters. Hemodynamic maturation is completed by the first postoperative week, while AVF is clinically functional, by the second. FV can be used for early prediction of maturation.

#3008 Very low protein diet with ketoanalogues supplementation could start haemodialysis with AVF without additional CVCs insertion

Abstract Background and Aims Nutritional interventions and a low-protein diet (LPD) are a critical point in the management of chronic kidney disease (CKD). Several protein-restricted dietary regimens have been proposed in patients with end stage kidney disease: a typical LPD provides around 0.6–0.7 g·kg meanwhile a very low-protein diet (VLPD) provides around 0.3–0.4 g·kg and it is basically a vegetarian diet which has to be supplemented with essential amino acids (EAA) to satisfy the body nitrogen need and with nitrogen-free ketoanalogues (KA) to recirculate the endogenous urea, whose serum levels are elevated in patients with CKD. KA and EAA reduce the rate of progression of chronic kidney disease and improve the inflammatory state; they reduce the absorption of phosphates and can maintain a good state of nutrition even if associated with diets with very low protein content. On the contrary, an excessively restrictive and inadequate diet in terms of EAA or calorie intake induces a negative nitrogen balance, therefore cachexia. The recommended vascular access to start dialysis treatment is represented by the arteriovenous fistula (AVF). An early referral to the vascular surgeon for vascular access creation is pivotal for deciding on a patient-specific strategy for planning access. Guidelines advise referral at least 3–6 months before the expected start of HD, because time is needed for AVF maturation and possible repeat interventions when it is impaired. An early referral results in more autologous AVFs, which have a better long-term patency, whereas late referral, results in a greater risk of AVF non-maturation and failure and therefore the need for additional central venous catheters (CVCs) to initiate dialysis. Recent studies have shown that pre-dialysis patients who undergo a VLDP + KA require less emergency dialysis access and have better elasticity of the arterial wall, better maturation rates and duration of the AVF and sometimes a reduction in the uremic toxins responsible of endothelial dysfunction. The aim of the study was to evaluate if patients could start haemodialysis with fistula cannulation, without central venous catheter insertion. Method 10 patients, late referral end stage renal disease were enrolled in a prospective, single arm study starting very low protein diet supplemented with ketoanalogues after arteriovenous fistula creation; they were followed with periodically assessment of renal function, uremic toxin, and acid-base balance until they need to start haemodialysis. It was evaluated AVF maturation and needs to additional CVC insertion. Results Patients (3 females, 7 males) mean age was 71.2 years; before AVF creation, baseline mean value was: sCr: 6.46 mg/dl, sUrea: 150 mg/dl, phosphorus: 4.45 mg/dl, bicarbonates: 19.8 mmol/l, eGFR: 8,37 ml/min. After 3 months of VLPD supplemented with KA, eGFR and sCr was stable to 8.25 ml/min and 6.69 respectively, sUrea and phosphorus reduced to 115 mg/dl and 3.8 mg/dl, and bicarbonate increased to 22.4 mmol/l. All 10 patients achieved AVF maturation within 3 months, no one needed CVC insertion. Conclusion In this small group we see how late referral ESRD patients, undergone AVF surgery, after 3 months of VLPD supplemented with KA, had stability of renal function, with reduction of urea and phosphorus, improvement of acid-base balance and achievement of AVF maturation, without needing of CVC insertion. For these reasons VLPD + KA could be useful in delaying haemodialysis start in late referral ESRD patients who have created AVF, without emergency placement of a central venous catheter.

#2143 Unveiling key factors on arteriovenous fistulas maturation—a prospective observational study

Abstract Background and Aims The incidence of patients starting haemodialysis is increasing. While Arteriovenous Fistula (AVF) stands as the preferred vascular access method, a significant proportion of AVFs experience primary failure, with rates ranging from 20% to 65%. Moreover, around 50% require reintervention due to delayed maturation, resulting in increased costs and patient morbidity. Understanding the factors involved and their influence on AVF development is paramount. This analysis aims to improve the preoperative decision-making process, advocating for a personalized patient approach, thereby increasing the likelihood of success. Method A prospective observational cohort study that included patients with chronic kidney disease either on dialysis or in the pre-dialysis stage. The study enrolled a total of 140 patients attending a multidisciplinary team appointment (including a vascular surgeon and a nephrologist) at a Tertiary Hospital Centre during the first semester of 2023, of whom 98 patients were included. Demographic characteristics, comorbidities, and vascular parameters observed through ultrasound underwent a comprehensive analysis. The newly formed fistulas were then thoroughly reassessed for maturation using both physical and ultrasound examinations. Results The cohort comprised 56.1% male, with a mean age of 71.06 ± 12.51 years. Among the newly formed fistulas, there were 35.7% (n = 35) radiocephalic fistulas, 46.9% (n = 46) brachiocephalic fistulas, and 17.3% (n = 17) brachiobasilic fistulas. Out of the total 98 AVFs, 59.2% (n = 58) AVFs were maturate and 11.22% (n = 11) AVFs had delayed maturation and were proposed for surgery or angiography procedure. Primary failure occurred in 29.6% (n = 29) AVF, with 42.9% (n = 15) occurring in the forearm, and 22.2% (n = 14) in the upper arm. The major cause of primary failure was thrombosis, accounting for 93.1% (n = 27) of cases. The analysis unveiled that the absence of immediate post-operative thrill, forearm AVFs and previous fistula failure were associated with a higher likelihood of AVF primary failure and non-maturation. Conversely, a larger vein diameter was linked with a reduced likelihood of AVF primary failure, with a Youden Index-derived cut-off of 4.25 mm, with 40.9% sensitivity and 86.2% specificity (p &amp;lt; 0.05). No other clinical or ultrasound factors exhibited a statistically significant impact. Conclusion This study sheds light on the challenges faced in AVF maturation due to a high incidence of primary fistula failure and a maturation rate that only slightly surpasses 50%. A larger vein diameter emerges as a significant predictor of AVF maturation. Although the cut-off point for vein diameter is frequently cited as 2 mm, this value often varies in the literature. This study underscores the importance of considering higher vein diameters, but, more importantly, it suggests that establishing a rigid and uniform cut-off for all centres may not be beneficial. It is crucial to recognize that the optimal vascular characteristics may vary based on the unique circumstances of each centre and the specific needs and features of each patient. The lack of association between demographic parameters and comorbidities with primary failure, juxtaposed with the evidence of more susceptible patients to consecutive primary failure, underscores the need for further studies to explore the unique individual circumstances that may account for this phenomenon.

#1476 Impact of frailty on maturation of native arteriovenous fistula in patients with end-stage kidney disease

Abstract Background and Aims Morbimortality and quality of life in hemodialysis patients is directly related to the reliability and integrity of the vascular access. Current guidelines recommend a shift from a "fistula first" approach to a patient-centered approach due to the aging dialysis population. Frailty, defined as vulnerability to adverse health states due to impaired functional status, comorbidities and psychosocial factors, conditions a worse outcome of patients with end-stage kidney disease (ESKD) undergoing dialysis. Our aim was to assess frailty status before the performance of native arteriovenous fistulas (nAVF) as a predictor of failure to mature. Method Retrospective analysis of ESKD clinic patients who underwent a first nAVF between 2020-2022 and had undergone a frailty assessment before the surgery. The Frail-VIG index, evaluating frailty through deficit accumulation (scored from 0 to 1), vas employed. Patients were categorized as either non-frail (NF-ESKD: Frail-VIG &amp;lt; 0.2) or frail (F-ESKD: Frail-VIG ≥ 0.2). the study evaluated early nAVF and recorded the first ultrasound maturation values 4 weeks after surgery. Results Throughout the study period, 180 patients underwent a first nAVF, 57 (31.6%) having undergone a prior frailty assessment. 27 (47.4%) patients were classified as NF-ESKD, 30 (52.6%) as F-ESKD (23 mild, 6 moderate and 1 severe frailty). In the descriptive analysis, no differences in age, sex, toxic habits, CKD etiology or medical conditions were observed between the two groups (Table 1). Regarding surgical technique, there were no differences in nAVF location and laterality between the two groups (Table 1). F-ESKD patients had a higher primary fistula failure, defined as no flow prior to the first ultrasound evaluation (36.7% vs. 3.8%; p=0.002). In patients with an initial ultrasound evaluation, the F-ESKD group had lower arterial flow (1020.76 ± 589.42 vs. 1455.56 ± 679.78 ml/min; p=0.027) and smaller fistula diameter (4.52 ± 1.51 vs. 6.4 ± 1.61 mm; p=0.018). Maturation was assessed after the first ultrasound evaluation, defined as the presence of an arterial flow greater than 500 ml/min and a diameter greater than 4 mm. A higher proportion of frail patients (88.9% vs. 33.11%; p = 0.004), a lower capacity to perform instrumental activities measured by Lawton Brody index (4.63 ± 2.2 vs. 6.55 ± 2.2; p = 0.034) and a higher percentage of diabetic patients (88.89% vs. 48.48%; p = 0.033) were found in nAVF that had not reached ultrasound-guided maturity (Table 2). In a multivariate analysis adjusted for functional status, type of vascular access and comorbidities, the presence of frailty conferred a higher risk of fistula non-maturation (OR 11.42 95%CI 1.005 - 128.74; p = 0.049). Conclusion The prevalence of frailty is notable among in ESKD patients and contributes to a higher rate of failure in native nAVF. Within this population, adopting an individual approach to the selection of a definitive vascular access may prove both feasible and beneficial in ensuring optimal dialysis access.

#2795 In-silico assessment of arteriovenous fistula maturation with patient-specific computational hemodynamic models

Abstract Background and Aims Native arteriovenous fistula (nAVF) is the preferred access for haemodialysis (HD) treatment. Both the quality and complications of the haemodialysis technique are closely related to vascular access. nAVF maturation process includes several morphological changes affecting haemodynamics, with previous studies suggesting that it is highly related to AVF failure. Computational Fluid Dynamics (CFD) simulations by using idealized morphologies or the analysis of one patient-specific geometry have been proposed to understand the pathophysiology of maturation failure. However, it is difficult to correlate with clinical practice and therefore limits its use. The aim is to develop a patient-specific modelling time pipeline, incorporating the haemodynamics of the blood flow to real anatomical and morphological characteristics. Method Design: prospective computational simulation analysis of nAVF in 3 patients at 3 different stages: after fistula creation, (1 week), maturation (1 month) and post-maturation (6 months). Analysis: morphological and haemodynamic. Inclusion criteria: &amp;gt;18 years and end-stage chronic kidney disease. Variables and data: Once morphology was extracted from nAVF magnetic resonance imaging, generated meshes were refined and compiled to obtain a volumetric mesh. The boundary conditions of the model were defined and extracted using ultrasound nAFV data. Data were analyzed at the 3 stages. Models: A 3-element Windkessel model was used to simulate the pressure waveform to feed the vein of the system. In this model, clinical data were also considered to classify the patient as normotensive or hypertensive to estimate waveform parameters. The Windkessel model estimates wall shear stress (WSS), velocity and flow for all the points located in the mesh by making an analogy from an electric circuit resistance model. As validation, the flow obtained from the Windkessel model was compared with the one obtained from the ultrasound scan of the patient. Results Different temporal points were analyzed for each nAVF. Results from the simulations in Fig. 1, illustrating the evolution over time and development. The geometrical characteristics were found to significantly impact on flow dynamics. The area most affected by flow was the juxta-anastomotic section which showed higher magnitude distribution of WSS and velocity for all time-points. According to the analysis of the simulations, a perpendicular junction between the vein and the artery potentially resulted in less damage in this area (in WSS terms), being important to mitigate the AVF failure. At maturation stage (1 month) the analysis shows WSS distribution mainly located in the juxta-anastomotic section and decreased in magnitude regarding one week; therefore, this can be marked as the stabilization point for nAFV maturation. Conclusion

Impact of stage-specific limb function exercises guided by a self-management education model on arteriovenous fistula maturation status.

The exercise of limb function is the most economical and safe method to promote the maturation of arteriovenous fistula (AVF). However, due to the lack of a unified exercise standard in China, many patients have insufficient awareness of the importance of AVF, leading to poor effectiveness of limb function exercise. The self-management education model can effectively promote patients to take proactive health-related actions. This study focuses on the characteristics of patients during the peri-AVF period and conducts a phased limb function exercise under the guidance of the self-management education model to observe changes in factors such as the maturity of AVF. To assess the impact of stage-specific limb function exercises, directed by a self-management education model, on the maturation status of AVFs. This study is a randomized controlled trial involving 74 patients with forearm AVFs from the Nephrology Department of a tertiary hospital in Sichuan Province, China. Patients were randomly divided into an observation group and a control group using a random number table method. The observation group underwent tailored stage-specific limb function exercises, informed by a self-management education model which took into account the unique features of AVF at various stages, in conjunction with routine care. Conversely, the control group was given standard limb function exercises along with routine care. The assessment involves the maturity of AVFs post-intervention, postoperative complications, and the self-management level of the fistula in both groups patients. Analyses were conducted using SPSS version 23.0. Count data were represented by frequency and percentage and subjected to chi-square test comparisons. Measurement data adhering to a normal distribution were presented as mean ± SD. The independent samples t-test was utilized for inter-group comparisons, while the paired t-test was used for intra-group comparisons. For measurement data not fitting a normal distribution, the median and interquartile range were presented and analyzed using the Wilcoxon rank sum test. At the 8-wk postoperative mark, the observation group demonstrated significantly higher scores in AVF symptom recognition, symptom prevention, and self-management compared to the control group (P < 0.05). However, the variance in symptom management scores between the observation and control groups lacked statistical significance (P > 0.05). At 4 wk after the operation, the observation group displayed a superior vessel diameter and depth from the skin of the drainage vessels in comparison to the control group (P < 0.05). While the observation group did manifest elevated blood flow rates in the drainage vessels relative to the control group, this distinction was not statistically significant (P > 0.05). By the 8-wk postoperative interval, the observation group outperformed the control group with notable enhancements in blood flow rates, vessel diameter, and depth from the skin of drainage vessels (P < 0.01). Seven days following the procedure, the observation group manifested significantly diminished limb swelling and an overall reduced complication rate in contrast to the control group (P < 0.05). The evaluation of infection, thrombosis, embolism, arterial aneurysm stenosis, and incision bleeding showed no notable differences between the two groups (P > 0.05). By the 4-wk postoperative juncture, complications between the observation and control groups were statistically indistinguishable (P > 0.05). Stage-specific limb function exercises, under the guidance of a self-management education model, amplify the capacity of AVF patients to discern and prevent symptoms. Additionally, they expedite AVF maturation and mitigate postoperative limb edema, underscoring their efficacy as a valuable method for the care and upkeep of AVF in hemodialysis patients.

Artificial neural networks analysis predicts long-term fistula function in hemodialysis patients following percutaneous transluminal angioplasty

Kidney failure is particularly common in the United States, where it affects over 700,000 individuals. It is typically treated through repeated sessions of hemodialysis to filter and clean the blood. Hemodialysis requires vascular access, in about 70% of cases through an arteriovenous fistula (AVF) surgically created by connecting an artery and vein. AVF take 6 weeks or more to mature. Mature fistulae often require intervention, most often percutaneous transluminal angioplasty (PTA), also known as fistulaplasty, to maintain the patency of the fistula. PTA is also the first-line intervention to restore blood flow and prolong the use of an AVF, and many patients undergo the procedure multiple times. Although PTA is important for AVF maturation and maintenance, research into predictive models of AVF function following PTA has been limited. Therefore, in this paper we hypothesize that based on patient-specific information collected during PTA, a predictive model can be created to help improve treatment planning. We test a set of rich, multimodal data from 28 patients that includes medical history, AVF blood flow, and interventional angiographic imaging (specifically excluding any post-PTA measurements) and build deep hybrid neural networks. A hybrid model combining a 3D convolutional neural network with a multi-layer perceptron to classify AVF was established. We found using this model that we were able to identify the association between different factors and evaluate whether the PTA procedure can maintain primary patency for more than 3 months. The testing accuracy achieved was 0.75 with a weighted F1-score of 0.75, and AUROC of 0.75. These results indicate that evaluating multimodal clinical data using artificial neural networks can predict the outcome of PTA. These initial findings suggest that the hybrid model combining clinical data, imaging and hemodynamic analysis can be useful to treatment planning for hemodialysis. Further study based on a large cohort is needed to refine the accuracy and model efficiency.

The role of glomerular filtration rate in AVF success: Should we intervene earlier?

End-stage kidney disease (ESKD) patients require life-sustaining kidney replacement therapies, with the natural arteriovenous fistula (AVF) being the preferred vascular access due to its low infection risk, high patency, and fewer complications. Factors like vessel diameter, gender, diabetes, age, and surgical technique influence AVF maturation. Our study focused on short-term AVF creation success, specifically examining estimated glomerular filtration rate (eGFR) levels using the CKD-EPI formula. Patients were categorized according to their eGFR levels to observe the effects of fistula timing and the severity of kidney disease. No significant demographic or outcome differences between eGFR groups have been observed except for gender. AVF maturation was notably associated with distal vein diameter (>2mm), while other factors did not significantly impact maturation rates. As a secondary outcome, it was concluded that the recording of patients' blood pressure values at preoperative and perioperative levels led to the conclusion that blood pressure levels may have an impact on fistula maturation. To ensure vascular access effectiveness, optimizing blood pressure, determining vein diameter, strategic AVF timing, and reducing catheter usage are crucial. Our study aimed to identify eGFR levels conducive to optimal AVF outcomes. Although significant results could not be obtained in this regard, it is considered worthwhile to re-examine the effect of blood pressure in secondary outcomes. Additionally, prospective studies may be appropriate for reevaluating the effect of GFR.

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.

Snuffbox distal transradial access (dTRA) for arteriovenous fistuloplasty in Singapore: Going distal is safe.

Arteriovenous fistula (AVF) dysfunction resulting from stenosis or occlusion, is a prevalent issue in end-stage renal failure patients reliant on autogenous AVFs for dialysis. Recently, a distal transradial approach (dTRA) has emerged, offering advantages such as diminished access site complications, better patient comfort and reduced risk of radial artery occlusion. Our study seeks to assess the effectiveness, outcomes and complication rates of employing dTRA for arteriovenous fistuloplasty in Singaporean patients. A retrospective review of all dTRA fistuloplasties performed on dysfunctional or slow to mature AVFs from 2017 to 2023 in our institution was performed. Patients with a distal radial artery measuring 2 mm or more with no evidence of occlusion or thrombosis were included. Patients who required central venoplasty or cutting balloon angioplasty were excluded. Outcome measures included technical success, mean procedure duration, complications and post-intervention primary patency at 1, 3 and 6 months. Patients were followed up for 12 months post-intervention. A total of 37 patients were included. 97.3% of patients undergoing dTRA fistuloplasty had radiocephalic fistulas while 2.7% had brachiobasilic fistulas. There was 100% technical success (defined as success in radial artery cannulation, sheath insertion and crossing of stenotic lesions) in our study as all patients successfully underwent fistuloplasty via dTRA approach. One-month patency rate was 97.4%, 3-month patency rate was 92.1% and 6-month patency rate was 86.8%. There were no immediate complications (haematoma, infection, bleeding, pseudoaneurysm, occlusion) of the radial artery post-intervention. Our paper illustrates the safety and efficacy of utilising dTRA for arteriovenous fistuloplasty. This approach offers distinct benefits in addressing non-mature or dysfunctional distal forearm arteriovenous fistulas and should be taken into account in anatomically suitable cases.