Venous Distensibility as a Key Factor in the Success of Arteriovenous Fistulas at the Wrist

Distal Forearm Arteriovenous Fistula Maturation in Diabetic Hemodialysis Patients

PURPOSE

Atherosclerotic disease of the forearm arteries can impede the maturation of distal fistulas in diabetic patients. The goal of this study was to look at the maturity of diabetic hemodialysis patients' distal forearm (radiocephalic snuffbox or distal forearm) arteriovenous fistulas.

MATERIALS AND METHODS

Patients with chronic renal failure who were candidates for distal forearm radiocephalic arteriovenous fistula implantation were evaluated in this cross-sectional study. Patients' demographic details, underlying disorders, laboratory measurements, vital signs, and information on their surgery were all noted. Patients were checked for fistula development 1 week, 1 month, 2 months, and then monthly until 6 months after surgery. Arteriovenous fistula maturation characterized by optimal blood flow, vessel dilation, and structural adaptations.

RESULTS

Among 343 patients (56% male, 44% female, mean age: 57.32 ± 12.48 years), hypertension prevailed (81.9%), followed by hyperlipidemia (42.3%) and coronary artery disease history (25.9%). AVFs achieved 58.3% maturation in 64.98 ± 11.05 days; higher BP during creation correlated with successful maturation (17.02 ± 1.46 mmHg vs 13.90 ± 1.93 mmHg, P < .05). No significant statistical difference found in distal forearm arteriovenous fistula maturation between males (57.8%) and females (58.9%) (P > .005). However, 41.7% of AVFs failed in 18.83 ± 17.89 days. Failed AVFs exhibited lower BP during operation and failure (11.75 ± 1.86 mmHg). Kaplan-Meier analysis depicted maturation probabilities over 90 days post-surgery.

CONCLUSION

Diabetes and patient sex did not affect the maturation time of distal forearm AVFs in hemodialysis patients. Increased blood pressure during and after surgery correlated with shorter maturation time.

Therapeutic strategies based on non-ionizing radiation to prevent venous neointimal hyperplasia: the relevance for stenosed arteriovenous fistula, and the role of vascular compliance

We have reviewed the development and current status of therapies based on exposure to non-ionizing radiation (with a photon energy less than 10 eV) aimed at suppressing the venous neointimal hyperplasia, and consequentially at avoiding stenosis in arteriovenous grafts. Due to the drawbacks associated with the medical use of ionizing radiation, prominently the radiation-induced cardiovascular disease, the availability of procedures using non-ionizing radiation is becoming a noteworthy objective for the current research. Further, the focus of the review was the use of such procedures for improving the vascular access function and assuring the clinical success of arteriovenous fistulae in hemodialysis patients. Following a brief discussion of the physical principles underlying radiotherapy, the current methods based on non-ionizing radiation, either in use or under development, were described in detail. There are currently five such techniques, including photodynamic therapy (PDT), far-infrared therapy, photochemical tissue passivation (PTP), Alucent vascular scaffolding, and adventitial photocrosslinking. The last three are contingent on the mechanical stiffening achievable by the exogenous photochemical crosslinking of tissular collagen, a process that leads to the decrease of venous compliance. As there are conflicting opinions on the role of compliance mismatch between arterial and venous conduits in a graft, this aspect was also considered in our review.

Factors Affecting the Early Maturation of Arteriovenous Fistulae Created at a Tertiary Centre in Oman

Objectives

This study aimed to determine the risk factors associated with the failure of arteriovenous fistulae (AVF) maturation.

Methods

This retrospective cohort study was conducted from January 2014 to December 2018 in Sultan Qaboos University Hospital, Muscat, Oman. Patients were followed-up 3 months after surgery, and their electronic medical records were accessed for demographic and clinical data. Univariate analysis was used to determine the risk factors associated with early AVF maturation and multivariant analysis was used to determine the predictive factors for AVF failure.

Results

A total of 269 patients were included. Female gender was a significant factor affecting AVF maturity (P = 0.049), while age (P = 0.626), diabetes (P = 0.954), hypertension (P = 0.378), dyslipidaemia (P = 0.907), coronary artery disease (P = 0.576), cerebrovascular accident (P = 0.864), congestive heart failure (P = 0.685), previous central venous catheterisation (P = 0.05), fistula type (P = 0.863) and fistula site (P = 0.861) did not affect AVF maturation. Binary logistic regression showed that all the risk factors were insignificant. Failure of early AVF maturation affected 11.5% in the cohort.

Conclusion

This study found that the proportion of early AVF maturation at our hospital is at par with that in the international literature. Failure of AVF maturation was significantly associated with the female gender. These findings can help nephrologists and vascular surgeons prognosticate AVF maturation rates. However, a larger study is needed for definitive conclusions.

Model and online calculator for prediction of fistula maturation based on vein dilation and age: A retrospective cohort study in a single-center

OBJECTIVE

A model that considers the characteristics of dialysis patients may help predict successful fistula maturation. We evaluated factors associated with radiocephalic arteriovenous fistula (RCAVF) maturation at 3 months in dialysis patients with end-stage renal disease (ESRD).

METHODS

A total of 184 patients who received an initial RCAVF at Beijing Haidian Hospital (Haidian Section of Peking University Third Hospital) were recruited. Fistula maturation was assessed within 3 months. Patient characteristics and preoperative vascular assessment indices were examined. Factors associated with fistula maturation were analyzed using logistic regression and least absolute shrinkage and selection operator (LASSO) binary logistic regression. Boostrapping was used for internal validation.

RESULTS

The development data consisted of 184 ESRD patients receiving an initial RCAVF, 140 (76%) of whom achieved fistula maturation. The main predictors of RCAVF maturation in the final model were sex, age-adjusted vein dilation (eVD), radial artery volume (Vartery), and diastolic blood pressure. The difference of vein diameter with and without a tourniquet was significantly larger in the mature RCAVF group (3.0 ± 0.5 vs. 2.2 ± 0.5 mm). The area under receiver operating characteristic (AUROC) curve for prediction of fistula maturation was 0.77, and the Hosmer-Lemeshow statistic indicated agreement between observed and predicted values (P = 0.792). Analysis of internal validation using bootstrapping indicated the C-index was 0.75.

CONCLUSION

The ratio of vein dilation and age were the major predictors of fistula maturation at 3 months in our patients. The resulting online prediction model may help in clinical decision-making for patients receiving a RCAVF.

The FACT : Use of a novel intermittent pneumatic compression device to promote pre-surgery arm vein dilation in patients with chronic renal failure

BACKGROUND

Arteriovenous fistula (AVF) creation and maturation for hemodialysis is globally a topic of importance given the poor results and high costs associated with renal care. Successful AVF (surgical or endovascular) creation requires appropriate superficial veins and quality arteries. Many procedures fail due to initial small veins with limited blood flow capacity and distensibility. Intermittent pneumatic compression has previously shown success in trials to increase superficial veins in patients with end stage renal disease post AVF. The objective of this study is to investigate the role of an intermittent pneumatic device, the Fist Assist®, to dilate cephalic arm veins in patients with advanced chronic kidney disease (CKD) prior to AVF placement.

METHODS

Three centers enrolled subjects from June 2019 through July 2021. Baseline Doppler measurements of the cephalic vein in standard locations the forearm and upper arm with and without a blood pressure cuff were recorded. Patients were instructed and used Fist Assist® on their non-dominant arm for up to 4 h daily for 90 days. At approximately 3 months, Doppler measurements were repeated. The primary endpoint was cephalic vein enlargement with secondary endpoints based on percentage of veins approaching 2.5 mm in the forearm and 3.5 mm in the upper arm.

RESULTS

Thirty-seven subjects with CKD (mean eGFR 13.8 mL/min) were enrolled and completed the trial. Paired-difference t-tests (one tail) for aggregate data showed significant venous dilation of the cephalic vein in both the forearm and upper arm after use with the Fist Assist® (p < 0.05). Mean differences in the forearm veins were approximately 0.6 and 1.1 mm in the upper arm cephalic vein after Fist Assist® application. There were no major complications reported by any subject during the trial.

CONCLUSIONS

Fist Assist® use in patients with CKD is effective to enhance vein dilation. Forearm and upper arm cephalic veins increased on average 0.6 and 1.1 mm respectively after Fist Assist® application. This is the first trial to evaluate the effect of intermittent, focal pneumatic compression on pre-surgery vein diameter in patients with advanced CKD before AVF creation.

The feasibility of small-caliber veins for autogenous arteriovenous fistula creation: A single-center retrospective study

Objective

Autogenous arteriovenous fistula (AVF) is recommended as the first choice for hemodialysis vascular access. A small-caliber vein is one of the independent risk factors for AVF maturation and patency. However, the specific threshold is still unclear, making it difficult to accurately determine whether these vessels are suitable for AVF creation.

Design

This is a single-center retrospective study.

Method

Patients who underwent AVF creation in our medical center between January 2020 and September 2022 and satisfied the eligibility criteria were included in this retrospective study. Logistic regression analysis was performed to identify risk factors for functional maturation and additional intervention. The optimal cutoff value was determined based on the receiver operating curve (ROC) and the Youden index. Kaplan-Meier analysis was utilized in further patency rate comparisons.

Result

A total of 125 forearm AVFs were created in 121 patients with end-stage renal disease (ESRD). The mean age was 53.88 ± 15.10  years. Preoperative vascular Doppler ultrasound (DUS) was conducted and recorded in 106 cases (84.80%). The mean targeted artery and vein diameters were 2.17 ± 0.54 and 1.71 ± 0.75  mm, respectively. Small-caliber vein is the risk factor for functional maturation failure (OR = 0.256, 95%CI [0.06-0.75], p = 0.033) and additional intervention (OR = 0.306, 95% CI [0.09-0.78], p = 0.031). The optimal cutoff value is 1.35  mm (augmented) when specificity and sensitivity reach 80 and 63.7%, respectively. The AVFs with a vein diameter of more than 1.35 mm (augmented) showed higher patency rates (p < 0.01).

Conclusion

After comprehensive DUS evaluation, intraoperative hydrodilation, postoperative active exercise and intensive DUS detection, and application of balloon-assisted maturation, if necessary, using a vein more than 1.35 mm (augmented), could achieve satisfactory functional maturation and postoperative patency in AVF formation.

Ultrasound Measurement of Vascular Distensibility Based on Edge Detection and Speckle Tracking Using Ultrasound DICOM Data

This study presents an edge detection and speckle tracking (EDST) based algorithm to calculate distensibility as percentage of change of vessel diameter during cardiac cycles. Canny edge detector, Vandermonde matrix representation, Kanade Lucas Tomasi algorithm with pyramidal segmentation, and penalized least squares technique identifies the vessel lumen edge, track the vessel diameter, detrend the signal and find peaks and valleys when the vessel is fully distended or contracted. An upper extremity artery from 10 patients underwent an ultrasound examination as part of preoperative evaluation before arteriovenous fistula surgery. Three studies were performed to evaluate EDST with automatic peak and valley selection versus manual speckle selection of expert users using manual peak and valley selection. Results demonstrate the effectiveness of the proposed methodology, to obtain comparable results as those obtained by expert-users, and considerably reducing the variability associated with external factors such as excessive motion, fluctuations in stroke volume, beat-to-beat blood pressure changes, breathing cycles, and arm-transducer pressure.

Evaluation of Factors Affecting Wrist Radio-Cephalic Arteriovenous Fistula Maturation: A Single Institutional Observational Study

Background: Chronic renal failure is the most common indication for which arterio-venous (AV) fistula creation surgery is being performed. Various studies have found that native arteriovenous fistulas are the best in long-term patency with lower complications. We conducted this study to find out the role of preprocedural duplex ultrasound (DUS) in predicting outcomes of radio-cephalic fistula in the wrist in the North-Karnataka population. Methods: This prospective study was conducted from May 2019 to July 2020 on 50 patients who were hemodialysis-dependent and underwent AV fistula creation with age from 20 to 70 years. All the patients underwent preoperative DUS and were followed up post-operatively after one, two, and six weeks. Hemodialysis was initiated through the constructed fistula once it was mature, and the maximum blood flow through the fistula was measured. SPSS version 20.0 was used for statistical analysis. Results: Among 50 subjects, the overall cumulative success of AVF maturation was 86% (43), and failure to mature rate was 14% (7). Logistic regression of maturation outcome in the wrist autologous arteriovenous fistula for individual factors showed statistically significant results (P < 0.05) for the diameter of the radial artery > 1.6 mm and the distensibility of the cephalic vein > 0.4 mm. Conclusions: Vein distensibility and radial artery diameter are key factors in predicting successful AVF maturation. The use of intraoperative papaverine instillation directly on vessels can improve arteriovenous fistula outcomes.

Role of Doppler ultrasonography in the evaluation of hemodialysis arteriovenous access maturation and influencing factors

The goal of vascular access creation is to achieve a functioning arteriovenous fistula (AVF) or arteriovenous graft (AVG). An autologous fistula has been shown to be superior to AVG or to central venous catheters (CVCs) with lowest rate of re-intervention, but vessel obstruction or immaturity accounts for 20 % to 54% of cases with primary failure of AVF. This review is focused on the factors influencing maturation; indication and timing of preoperative mapping/creation of vascular access; ultrasound parameters for creation AVF/AVG; early postoperative complications following creation of a vascular access; ultrasound determinants of fistula maturation and endovascular intervention in vascular access with maturation failure. However, vascular accesses that fail to develop, have a high incidence of correctable abnormalities, and these need to be promptly recognized by ultrasonography and managed effectively if a high success rate is to be expected. We review approaches to promoting fistula maturation and duplex ultrasonography (DUS) of evaluating vascular access maturation.

Venous distensibility is more important than venous diameter in primary survival of autogenous radiocephalic arteriovenous fistulas

BACKGROUND

Many studies suggested that the optimal cephalic vein diameter for wrist radio-cephalic arteriovenous fistula construction should be at least 2 mm to predict successful maturation and primary patency. However, our experience has shown that many patients with smaller cephalic vein diameter (≤2 mm) in the neutral state (without a tourniquet) also have good clinical outcomes. The aim of this study was to identify predictors that affect primary survival of new wrist radio-cephalic arteriovenous fistula in patients with cephalic vein diameter ≤2 mm.

METHODS

We performed a retrospective review of 50 patients with preoperative cephalic vein diameters ≤2 mm in the neutral state who underwent wrist radio-cephalic arteriovenous fistula construction between September 2016 and October 2019. Internal diameters of the cephalic vein and radial artery, venous distensibility, peak systolic velocity, and resistance index of the radial artery were determined by ultrasound examination before wrist radio-cephalic arteriovenous fistula placement. Patients were divided into two groups: failure and survival.

RESULTS

The radio-cephalic arteriovenous fistula survival rate was 68% from the time of radio-cephalic arteriovenous fistula creation until the end of the study. Univariate analysis showed that larger venous distensibility (p < 0.001), non-diabetic kidney disease (p = 0.009), and slower peak systolic velocity of the radial artery (p = 0.033) were predictive factors for primary radio-cephalic arteriovenous fistula survival. Multivariate regression analysis revealed good venous distensibility (odds ratio = 9.637, 95% confidence interval = 1.893-49.050, p = 0.006) and non-diabetic kidney disease (odds ratio = 0.148, 95% confidence interval = 0.033-0.660, p = 0.012) to be independent predictors for primary radio-cephalic arteriovenous fistula survival. Receiver operating characteristic analysis showed that venous distensibility >0.52 mm (sensitivity: 70.6%, specificity: 68.8%) was the best cut-off value to predict primary radio-cephalic arteriovenous fistula survival.

CONCLUSION

When cephalic veins with diameter ≤2 mm are found, venous distensibility should be used to aid in the surgery decision-making process. The outcome of wrist radio-cephalic arteriovenous fistula survival would be significantly improved through the use of cephalic vein with venous distensibility >0.52 mm.

Molecular Targets for Improving Arteriovenous Fistula Maturation and Patency

The increasing prevalence of chronic and end-stage renal disease creates an increased need for reliable vascular access, and although arteriovenous fistulae (AVF) are the preferred mode of hemodialysis access, 60% fail to mature and only 50% remain patent at one year. Fistulae mature by diameter expansion and wall thickening; this outward remodeling of the venous wall in the fistula environment relies on a delicate balance of extracellular matrix (ECM) remodeling, inflammation, growth factor secretion, and cell adhesion molecule upregulation in the venous wall. AVF failure occurs via two distinct mechanisms with early failure secondary to lack of outward remodeling, that is insufficient diameter expansion or wall thickening, whereas late failure occurs with excessive wall thickening due to neointimal hyperplasia (NIH) and insufficient diameter expansion in a previously functional fistula. In recent years, the molecular basis of AVF maturation and failure are becoming understood in order to develop potential therapeutic targets to aide maturation and prevent access loss. Erythropoietin-producing hepatocellular carcinoma (Eph) receptors, along with their ligands, ephrins, determine vascular identity and are critical for vascular remodeling in the embryo. Manipulation of Eph receptor signaling in adults, as well as downstream pathways, is a potential treatment strategy to improve the rates of AVF maturation and patency. This review examines our current understanding of molecular changes occurring following fistula creation, factors predictive of fistula success, and potential areas of intervention to decrease AVF failure.

Maturation of arteriovenous fistula: Analysis of key factors

The growing proportion of individuals suffering from chronic kidney disease has considerable repercussions for both kidney specialists and primary care. Progressive and permanent renal failure is most frequently treated with hemodialysis. The efficiency of hemodialysis treatment relies on the functional status of vascular access. Determining the type of vascular access has prime significance for maximizing successful maturation of a fistula and avoiding surgical revision. Despite the frequency of arteriovenous fistula procedures, there are no consistent criteria applied before creation of arteriovenous fistulae. Increased prevalence and use of arteriovenous fistulae would result if there were reliable criteria to assess which arteriovenous fistulae are more likely to reach maturity without additional procedures. Published studies assessing the predictive markers of fistula maturation vary to a great extent with regard to definitions, design, study size, patient sample, and clinical factors. As a result, surgeons and specialists must decide which possible risk factors are most likely to occur, as well as which parameters to employ when evaluating the success rate of fistula development in patients awaiting the creation of permanent access. The purpose of this literature review is to discuss the role of patient factors and blood markers in the development of arteriovenous fistulae.

Preoperative ultrasound still valuable for radio-cephalic arteriovenous fistula creation?

Radio-cephalic arteriovenous fistula is a prototype hemodialysis access with small incidences of infection and distal ischemia, it spares proximal veins for future access use and it helps in the maturation of veins that may be used for more proximal access creations. This access type is prone to higher early failure rates compared to more proximal fistulas and there are unsolved uncertainties regarding exact ultrasound parameters predictive of fistula outcome. Evolution of ultrasound use has yielded several functional parameters that can be measured in addition to anatomical lumen sizes, which remain core parameters on which the decision to construct fistula in radio-cephalic forearm position is based. We propose to use arterial hyperemic response and wall morphology to aid in this decision when radial artery diameter falls in the interval with predictive uncertainty of 1.6-1.9 mm and to use venous flow pattern, respiratory variation, radial artery status and possibly venous distensibility when cephalic vein augmented diameter lies in the borderline interval of 2-2.4 mm. Ultrasound preoperative mapping and planning should be followed by expert surgical technique and several technique modifications of the classical end-to-side approach are possible to enhance operation outcome and diminish the incidence of stenosis most often present at juxta-anastomotic location. In our experience radio-cephalic arteriovenous fistula remains the golden standard for hemodialysis access and preoperative ultrasound the single best imaging modality to plan the operation and predict its success.

Preoperative vessel mapping in chronic kidney disease patients - a center experience

PURPOSE

Hemodialysis (HD) is the main treatment modality in stage 5 chronic kidney disease, and vascular access planning is a crucial step in the path to dialysis treatment. Beyond detailed patient history and physical examination, duplex ultrasound (DU) evaluation is essential in preoperative vascular mapping.

METHODS

A retrospective descriptive nonrandomized study was performed and included 108 end-stage kidney disease patients referred from eight HD centers to be assessed for creation of an arteriovenous (AV) access (AV fistula or AV graft). We assessed primary failure, primary unassisted patency (PP) and primary assisted patency (PAP) rates and cumulative survival of AV accesses at 6 and 12 months.

RESULTS

We created 86 AV accesses of which 79 (91.9%) were AV fistulas (AVFs) (29 distal AVFs, 49 proximal AVFs and 1 femorofemoral AVF) and 7 (8.1%) arteriovenous grafts (AVGs). Fifteen percent (15%) (n = 12) of primary failure occurred in the AVF group. Any case of primary failure was observed between AVGs.In the AVF group, PP at 6 months was 63.8 % and at 12 months was 48.3%, PAP was 80.7% at 6 and 12 months. PP excluding primary failures was 73.0% and 55.3% at 6 and 12 months, respectively. The cumulative survival at 6 and 12 months was 80.7%.In the AVG group, PP at 6 months and 12 months was 66.7%, PAP and cumulative survival at 6 and 12 months were of 100%.

CONCLUSIONS

This study demonstrates that preoperative vascular mapping with a patient-centered approach may be critical to achieve good outcomes allowing the increase in AVF access.

Assessment of micro-mechanical variations in experimental arteriovenous fistulae using atomic force microscopy

PURPOSE

This study presents a method to quantify micro-stiffness variations in experimental arteriovenous fistulae (AVF).

METHODS

AVF created by anastomosing the superficial epigastric vein to the femoral artery in Sprague-Dawley rats were allowed to remodel for 21 days before being harvested and preserved in culture medium. A custom atomic force microscope was used to measure microvascular stiffness (Young's modulus) in three areas of the AVF: the inflow artery, the juxta-anastomotic area, and the outflow vein. Morphometric measurements and collagen and elastin contents were also determined.

RESULTS

Atomic force microscopy indentation revealed an increased stiffness in the juxta-anastomotic area of the AVF compared to the outflow vein and inflow artery. The juxta-anastomotic area was also significantly stiffer than the contralateral vein. The lack of elasticity (higher Young's modulus) of the juxta-anastomotic region was associated with a thicker vascular wall that was rich in collagen but poor in elastin.

CONCLUSIONS

This study demonstrates for the first time the feasibility of using atomic force microscopy to measure local stiffness variations in experimental AVF. This technique could be instrumental in advancing our understanding of how micro-spatial organization of the AVF wall determines the overall biomechanical performance of this type of vascular access.

Does Vascular Elasticity Affect Arteriovenous Fistula Maturation?

The vasculopathy of ESRD affects both arteries and veins. The arteries develop arteriosclerosis, which is largely a disease of the media characterized by increased collagen content, calcification, and both hypertrophy and hyperplasia of vascular smooth muscle cells. Veins may exhibit increased width of the intimal and medial layers, and may develop neointimal hyperplasia and calcification. Successful fistula maturation depends upon dilatation and remodeling of the artery and vein, but the stiff and thickened vessels of ESRD patients may respond poorly to signals that promote these adaptations. There is intense interest in accurately predicting fistula maturation outcome and preventing maturation failure. However, definitive criteria for preoperative testing of vessel elasticity have not yet been established. Tests that are adopted for widespread clinical use will need to be easy to apply - a standard that many of these tests may not meet. Finally, effective treatments are needed that prevent or reduce the stiffness of vessels. In conclusion, although there are many promising developments in this emerging field, effective methods of predicting fistula maturation outcome and preventing maturation failure remain to be established.

Morphologic and Functional Vessels Characteristics Assessed by Ultrasonography for Prediction of Radiocephalic Fistula Maturation

Purpose

Although native radiocephalic arteriovenous fistula (RCAVF) is the best vascular access for hemodialysis (HD), a major obstacle to increase its use is high frequency of fistulas that fail to mature. The aim of this study was to investigate and define cut-off values of morphologic and functional vessel parameters influencing successful RCAVF maturation using ultrasound.

Methods

A prospective, observational study was performed on 122 patients (66 men) who underwent primary RCAVF creation. Internal diameters of cephalic vein (CVd) and radial artery (ARd), venous distensibility (VD), resistance index (RI) and endothelial function by flow mediated dilatation (FMD) were determined by ultrasound examination before AVF placement. AVF maturation was observed by measuring blood flow (Qa) and CVd 0, 14 and 28 days after creation. Depending on the time when AVFs attained maturity (Qa ≥500 mL/min, CVd ≥5 mm), patients were divided into three groups: (i) successful maturation (after four weeks), (ii) prolonged maturation (within eight weeks) and (iii) failure to mature.

Results

Only 11% of patients failed to achieve a mature RCAVF. Successful AVF maturation occurred in 53% of patients and prolonged maturation in 36% of patients. ROC analysis defined the limits of variables relevant for RCAVF success (CVd >1.8 mm, ARd >1.6 mm, VD >0.4 mm). Female sex was associated with prolonged maturation (OR 0.35, 95% CI=0.17-0.72; P=0.005) having a significantly smaller ARd (1.83 vs. 2.01 mm, P=0.01) but better FMD (2981.5 vs. 2689.5, P=0.02) compared to men.

Conclusions

ARd ≤1.6 mm, CVd ≤1.8 mm and VD ≤0.4 mm are exact cut-off points, which best predict nonmaturation of RCAVF. Women need extended time for adequately matured AVF.