Pre-operative Radial Arterial Diameter Predicts Early Failure of Arteriovenous Fistula (AVF) for Haemodialysis

A cross-sectional study: Relationship between serum oxidative stress levels and arteriovenous fistula maturation in maintenance dialysis patients

Objective

This study was to investigate the relationship between serum superoxide dismutase (SOD) and malondialdehyde (MDA) and arteriovenous fistula (AVF) maturation in maintenance hemodialysis (MHD) patients.

Methods

A total of 120 MHD patients were divided into a maturation group (72 patients) and a maturation failure group (48 patients). General information and ultrasound data were collected and venous blood was drawn for routine blood tests. General data and serum SOD and MDA were compared. Independent variables with statistically significant (P < 0.05) differences in univariate analysis were included in multivariate logistic regression. Serum SOD and MDA in predicting maturation failure of AVF were analyzed using receiver operating characteristic curves.

Results

The internal diameter of the cephalic vein, internal diameter of the cephalic vein after tourniquet binding, internal diameter of the radial artery, and serum SOD level were lower and serum MDA level was higher in the maturation failure group. Reduced SOD and elevated MDA were independent risk factors for maturation failure of AVF. The area under the curve (AUC) for serum SOD and MDA was 0.68 each. When combined, their AUC for predicting AVF maturation failure was 0.79.

Conclusion

Reduced serum SOD and increased MDA are risk factors affecting AVF maturation in MHD patients.

Vessel diameter and radiocephalic arteriovenous fistula: A meta-analysis and Markov model

OBJECTIVE

The aim of this study was to determine the optimal radial artery (RA) and cephalic vein (CV) diameter for the best functional maturation (FM) of radiocephalic arteriovenous fistula with their financial implication.

METHODS

A systematic review and meta-analysis following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines included 4610 patients. The data was initially subjected to Pearson correlation to evaluate success-to-failure ratios on the endpoint of FM, to rule out the impact of confounders. This allowed for the meta-analysis using a random-effects model, assessing odds ratios (ORs) at 95% confidence intervals (CIs) relative to the line of no effect. Outcomes were subjected to Markov chain model, incorporating transition probabilities and sequential decision-making. Post-hoc analysis was performed to assess the adequacy of the sample size. This review is registered with International Prospective Register for Systematic Review (PROSPERO): CRD42022348509.

RESULTS

There was a moderate negative correlation (r = -0.44; P > .05), indicating no significant linear relationship. A CV diameter of 2 to 2.4 mm was associated with the best FM (OR, 1.29; 95% CI, 1.01-1.65; P < .04), whereas an RA diameter of 2 mm achieved an OR of 1.27 (95% CI, 0.95-1.7). The cost per arteriovenous fistula creation was £3079 for CV-based and £4285 for RA-diameter based approach. The CV diameter of 2 to 2.4 mm was the most cost-effective at £2411. Post-hoc power analysis confirmed the adequacy of the sample size with an effect size of d = 0.547 for an objective inference.

CONCLUSIONS

Superior maturation is plausible with a CV diameter of 2 to 2.4 mm and a RA diameter of 2 mm or more. Diameters below these thresholds yield poorer outcomes, whereas larger diameters provide no additional benefit.

Trends in Venous Diameter and Brachial Artery Volume Flow of arteriovenous fistula in 12 Weeks Postoperatively

BACKGROUND

To explore the trends of venous diameter and brachial artery volume flow (VF) in 12 weeks after arteriovenous fistula (AVF) and the influence of preoperative arterial diameter on this trend. Our goal was to clarify the maturation process within 12 weeks after AVF surgery.

METHODS

Clinical data of 257 patients with end-stage renal disease who had their first radial-cephalic AVF established at our institution from February 1, 2023, to February 1, 2024, were included. The patients were divided into group A (radial artery diameter <1.5 mm), group B (radial artery diameter 1.5-2.0 mm), and group C (radial artery diameter >2.0 mm) according to the preoperative radial artery diameter. After AVF surgery, the artery and vein diameter and brachial artery VF were recorded at 1 day, 2 weeks, 4 weeks, 6 weeks, 8 weeks, 10 weeks, and 12 weeks.

RESULTS

The venous diameter and brachial artery VF of AVF showed an upward trend and increased significantly in 1 day-6 weeks postoperatively (P < 0.05), especially between 1 day and 2 weeks, while no significant difference in the increases at 6-12 weeks. Groups B and C were in line with the above trend, whereas the patients in group A showed best growth in 2-4 weeks postoperatively. The natural maturation rates of AVF in groups B and C were significantly better than that of group A at all postoperative time (P＜0.05).

CONCLUSIONS

The AVF was in a developmentally dominant stage at 6 weeks postoperatively, with 1 day-2 weeks being particularly prominent. The postoperative natural maturation rate of AVF with arteries diameter of <1.5 mm was low; the direct use of such arteries to establish AVF needs careful consideration.

A prospective study of factors associated with successful maturation of arteriovenous fistulas for hemodialysis

Aim

Our objective was to determine the factors associated with the successful maturation of arteriovenous fistulas during hemodialysis.

Material and methods

This prospective study included patients treated with hemodialysis and predialysis patients. Clinical, biochemical, sociodemographic, vascular ultrasound mapping, flow-mediated dilatation, and surgical factors were analyzed. Success in the maturation process was defined by ultrasonographic criteria at six weeks.

Results

Thirty-seven patients were included. With a mean ± standard deviation age of 40 ± 14 years, 73% were male, 65% had type-2 diabetes mellitus, and 95% had hypertension. Arteriovenous fistulas were brachycephalic in 18 patients (49%), brachymedian in nine patients (24%), brachycommunicating posterior in five patients (14%), brachibasal in three patients (8%), radiocephalic in two patients (8%), and radiocephalic in two patients (5%). Fourteen percent of patients had unsuccessful maturation. The vein diameter was 4.3 ± 1.0 mm (maturation group) vs 3.2 ± 0.9 mm (non-maturation group), p = 0.04. The artery diameter was similar: 4.5 ± 0.6 vs 4.5 ± 0.4, p = 0.88. Logistic regression analysis revealed that the diameter of the vein for which the surgery was performed was the factor associated with successful maturation in our population, odds ratio = 4.77 (1.14-19.97), p-value = 0.032.

Conclusions

It is highly important to plan vascular access in patients to perform vascular mapping and measure veins and arteries in patients. Vein measurement is a significant factor in successful maturation of the arteriovenous fistulas.

Preoperative assessment for vascular access: Vascular mapping and handgrip strength

BACKGROUND

Reliable vascular access (VA) is required for patients receiving chronic hemodialysis (HD) treatment. Vascular mapping using duplex doppler ultrasonography (DUS) can aid in planning VA construction. Greater handgrip strength (HGS) was found to be associated with more developed distal vessels both in chronic kidney disease (CKD) patients and healthy individuals, and patients with lower HGS had worse morphologic vessel characteristics and were, therefore, less likely to construct distal VA.

OBJECTIVES

This study aims to describe and analyze clinical, anthropometric, and laboratory characteristics of patients who underwent vascular mapping prior to VA creation.

RESEARCH DESIGN

Prospective analysis.

SUBJECTS

Adult patients with CKD referred for vascular mapping, at a tertiary center, between March 2021 and August 2021.

MEASURES

Preoperative DUS by a single experienced nephrologist was carried out. HGS was measured using a hand dynamometer, and PAD was defined as ABI < 0.9. Sub-groups were analyzed according to distal vasculature size (<2 mm).

RESULTS

A total of 80 patients were included, with a mean age of 65.7 ± 14.7 years; 67.5% were male, and 51.3% were on renal replacement therapy (RRT). Twelve (15%) participants had PAD. HGS was higher in the dominant arm (20.5 ± 12.0 vs 18.8 ± 11.2 kg). Fifty-eight (72.5%) patients had vessels smaller than 2 mm in diameter. There were no significant differences between groups concerning demographics or comorbidities (diabetes, HTN, PAD). HGS was significantly higher in patients with distal vasculature greater than or equal to 2 mm in diameter (dominant arm: 26.1 ± 15.5 vs 18.4 ± 9.7 kg, p = 0.010; non-dominant arm: 24.1 ± 15.3 vs 16.8 ± 8.6, p = 0.008).

CONCLUSIONS

Higher HGS was associated with more developed distal cephalic vein and radial artery. Low HGS might be an indirect sign of suboptimal vascular characteristics, which might help predict the outcomes of VA creation and maturation.

Improved Ultrasound-Guided Balloon-Assisted Maturation Angioplasty Using Drug-Eluting Balloons in the First Autogenous Arteriovenous Fistula Procedure: Early Experience

In patients with end-stage renal failure requiring hemodialysis, autogenous arteriovenous fistula (AVF) is preferred over tunneled dialysis catheters due to lower complications and costs. However, AVF maturation failure remains a common issue due to small vein size, multiple venipunctures, and other factors. Guidelines recommend using vessels of >2 mm for forearm AVFs and >3 mm for upper arm AVFs. This study investigates the use of intraoperative Doppler ultrasound (DUS)-guided Balloon-Assisted Maturation (BAM) with drug-eluting balloons (DEB) during initial AVF creation. Data from 114 AVF procedures, of which 27.2% underwent BAM, were analyzed. BAM was performed in 25 distal radio-cephalic and 6 proximal brachio-cephalic AVFs. With DUS guidance, vein stenosis was identified and treated using DEB. Technical success was achieved in all cases, with no early mortality. Early BAM-related complications were minimal, and no AVF thrombosis occurred. AVF maturation time was 15 days (SD: 3), and no further complications were reported during a mean follow-up of 10.38 months. Using BAM with DEB during AVF creation led to successful maturation and dialysis use without the need for secondary procedures. This study emphasizes the importance of identifying AVF failure risk early and utilizing DUS-guided procedures to enhance AVF outcomes. A more liberal use of intraoperative BAM could limit reinterventions in patients undergoing AVFs.

Guidelines on vascular access for hemodialysis from the Brazilian Society of Angiology and Vascular Surgery

Chronic kidney disease is a worldwide public health problem, and end-stage renal disease requires dialysis. Most patients requiring renal replacement therapy have to undergo hemodialysis. Therefore, vascular access is extremely important for the dialysis population, directly affecting the quality of life and the morbidity and mortality of this patient population. Since making, managing and salvaging of vascular accesses falls within the purview of the vascular surgeon, developing guideline to help specialists better manage vascular accesses for hemodialysis if of great importance. Thus, the objective of this guideline is to present a set of recommendations to guide decisions involved in the referral, evaluation, choice, surveillance and management of complications of vascular accesses for hemodialysis.

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

BACKGROUND

There is no consensus of the optimal arterial and venous sizes on arteriovenous fistula (AVF) function and patency. The purpose of our study was to determine the influence of vein and artery sizes on maturation and patency in autologous first time AVF in a vascular access clinic of Mexican Social Security.

METHODS

Approved IRB single-center retrospective study in patients referred for their first AVF from 01/2018/ to 04/2020. Perianastomotic inner vein diameter and single inner artery diameter was recorded by duplex ultrasound. Outcomes were: failure to mature (FTM) and cumulative primary patency survival.

RESULTS

Eighty-six AVF's were created (mean age 45.5 ± 15.1 years; 62.8% male; mean BMI 25.9 ± 4.3 kg/m2). About 86% were brachiocephalic AVF. Eight (8.1%) AVF had FTM. Mean follow-up was 19.7 ± 8.5 months. Two-year patency survival was 81.4%. FTM vein and artery diameters (2.1 ± 0.3 and 2.8 ± 0.7 mm respectively) were smaller than successful AVF's (3.1 ± 0.9 and 3.5 ± 0.6 mm) (p < 0.05). ROC curve calculated a 2.15 mm vein diameter cutoff (AUC: 0.86) and a 2.95 mm artery diameter cutoff (AUC: 079) for FTM AVF's (83% sensitivity, 72% specificity both) (p < 0.05). AVF's created with a vein diameter <2.15 mm and <2.95 mm artery diameter had statistically significant lower patency survival than AVF's with larger vein and artery diameters (p < 0.05).

CONCLUSION

Vein diameter <2.15 mm and artery diameter <2.95 mm influences AVF maturation and patency in a Mexican population.

The Predictive Value of Systemic Inflammatory Markers, the Prognostic Nutritional Index, and Measured Vessels' Diameters in Arteriovenous Fistula Maturation Failure

Background: An arteriovenous fistula (AVF) is the first-line vascular access pathway for patients diagnosed with end-stage renal disease (ESRD). In planning vascular access, it is necessary to check the diameters of the venous and arterial components for satisfactory long-term results. Furthermore, the mechanism underlying the maturation failure and short-term patency in cases of AVFs is not fully known. This study aims to verify the predictive role of inflammatory biomarkers (the neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), systemic inflammatory index (SII), and C-reactive protein (CRP)), Ca-P product, the prognostic nutritional index (PNI), and the diameters of the venous and arterial components in the failure of AVF maturation. Methods: The present study was designed as an observational, analytical, and retrospective cohort study with a longitudinal follow-up, and included all patients with a diagnosis of ESRD that were admitted to the Vascular Surgery Clinic of the Targu Mures Emergency County Hospital, Romania, between January 2019 and December 2021. Results: The maturation of AVF at 6 weeks was clearly lower in cases of patients in the high-NLR (31.88% vs. 91.36%; p < 0.0001), high-PLR (46.94% vs. 85.55%; p < 0.0001), high-SII (44.28% vs. 88.89%; p < 0.0001), high-CRP (46.30% vs. 88.73%; p < 0.0001), high-Ca-P product (40.43% vs. 88.46%; p < 0.0001), and low-PNI (34.78% vs. 91.14%; p < 0.0001) groups, as well as in patients with a lower radial artery (RA) diameter (40% vs. 94.87%; p = 0.0009), cephalic vein (CV) diameter (44.82% vs. 97.14%; p = 0.0001) for a radio-cephalic AVF (RC-AVF), and brachial artery (BA) diameter (30.43% vs. 89.47%; p < 0.0001) in addition to CV diameter (40% vs. 94.59%; p < 0.0001) for a brachio-cephalic AVF (BC-AVF), respectively. There was also a significant increase in early thrombosis and short-time mortality in the same patients. A multivariate analysis showed that a baseline value for the NLR, PLR, SII, CRP, Ca-P product, and PNI was an independent predictor of adverse outcomes for all of the recruited patients. Furthermore, for all patients, a high baseline value for vessel diameter was a protective factor against any negative events during the study period, except for RA diameter in mortality (p = 0.16). Conclusion: Our findings concluded that higher NLR, PLR, SII, CRP, Ca-P product, and PNI values determined preoperatively were strongly predictive of AVF maturation failure, early thrombosis, and short-time mortality. Moreover, a lower baseline value for vessel diameter was strongly predictive of AVF maturation failure and early thrombosis.

Clinical and ultrasound evaluation for hemodialysis access creation

Chronic kidney disease (CKD) is an emerging global burden with an increasing number of patient's requiring renal replacement therapy (RRT), with hemodialysis being the most prevalent dialysis modality. A functioning vascular access remains the main constrain for an adequate treatment. Clinical and, in some patients, ultrasound evaluation are fundamental for better access planning. Access planning is dependent not only on patient clinical characteristics and preference but also in vascular patrimony. As such, ultrasound evaluation aids in characterizing patient arterial and venous upper arm anatomy and provides information for which access would better suit each patient. Doctors dealing with CKD patients should be familiar with the role of ultrasound and Doppler use in access planning.

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.

Vessel diameter and close surveillance helps predict early patency in native arteriovenous fistulas

INTRODUCTION

Arteriovenous fistulas are the preferred method of vascular access for haemodialysis. Data suggests patency rates can be low and may be related to vessel diameters prior to creation. We use specific size criteria for fistula selection. We aimed to establish patency rates in relation to vessel size and whether other factors affect fistula patency.

METHODS

Consecutive patients undergoing radiocephalic (RCF) or brachiocephalic (BCF) creation between 2016 and 2018 were analysed. Preoperative arterial and venous diameters were collected. Six-week and six-month primary and secondary patency rates were analysed to establish any impact of vessel size on patency and re-intervention rates between groups. A univariate analysis was performed.

RESULTS

Ninety four RCFs and 101 BCFs were created. Median artery and vein size for RCF were 2.7 and 3.0 mm respectively. For BCF, they were 4.6 and 4.3 mm respectively. At 6-weeks, overall satisfactory patency for RCF and BCF combined was 91.8%. 89.7% demonstrated primary patency; 2.1% secondary patency. At 6-months, overall patency was 78.7%; 58.5% demonstrated primary patency, 20.2% secondary patency. A univariate analysis, for both groups, revealed vein size was a significant predictor of overall satisfactory patency at 6-weeks, with larger veins more likely to remain patent (p = 0.025 RCF, p = 0.007 BCF). However, artery size was not predictive (p = 0.1 RCF, p = 0.5 BCF). At 6-months, neither artery nor vein diameter were predictive in either group. When comparing size of vessel based on fistula type, vessels used to create RCFs were smaller than those for BCFs (p < 0.001). RCFs were more likely to receive endovascular intervention or occlude when compared to BCFs (p = 0.014).

DISCUSSION

Excellent patency and maturation rates can be achieved using fairly strict vessel size criteria. Vein size might be the more important predictor of early success. RCFs can be challenging due to smaller vessels, but maturation rates can be optimised by close surveillance and aggressive re-intervention.

Current role of ultrasound in hemodialysis access evaluation

Physical examination (PE) is considered the backbone before vascular access (VA) placement, during maturation period and for follow-up. However, it may be inadequate in identifying suitable vasculature, mainly in comorbid patients, or in detecting complications. This review highlights the advantages of ultrasound imaging to manage VA before placement, during maturation and follow-up. Furthermore, it analyses the future perspectives in evaluating early and late VA complications thank to the availability of multiparametric platforms, point of care of ultrasound, and portable/wireless systems. Technical improvements and low-cost systems should favor the widespread ultrasound-based VA surveillance programs. This significant turning point needs an adequate training of nephrologists and dialysis nurses and the standardization of exams, parameters, and procedures.

Detecting High-Resolution Intramural Vascular Wall Strain Signals Using DICOM Data

Maintaining dialysis vascular access is a source of considerable morbidity in patients with end-stage renal disease (ESRD). High-resolution radiofrequency (RF) ultrasound vascular strain imaging has been applied experimentally in the vascular access setting to assist in diagnosis and management. Unfortunately, high-resolution RF data are not routinely accessible to clinicians. In contrast, the standard DICOM formatted B-mode ultrasound data are widely accessible. However, B-mode, representing the envelope of the RF signal, is of much lower resolution. If strain imaging could use open-source B-mode data, these imaging techniques could be more broadly investigated. We conducted experiments to detect wall strain signals with submillimeter tracking resolutions ranging from 0.2 mm (3 pixels) to 0.65 mm (10 pixels) using DICOM B-mode data. We compared this submillimeter tracking to the overall vascular distensibility as the reference measurements to see if high-strain resolution strain could be detected using open-source B-Mode data. We measured the best-fit coefficient of determination between signals, expressed as the percentage of strain waveforms that exhibited a correlation with a p value of 0.05 or less. The lowest percentage was 86.7%, and most were 90% and higher. This indicates high-resolution strain signals can be detected within the vessel wall using B-mode DICOM data.

Clinical and ultrasound evaluation for hemodialysis access creation

Chronic kidney disease (CKD) is an emerging global burden with an increasing number of patient's requiring renal replacement therapy (RRT), with hemodialysis being the most prevalent dialysis modality. A functioning vascular access remains the main constrain for an adequate treatment. Clinical and, in some patients, ultrasound evaluation are fundamental for better access planning. Access planning is dependent not only on patient clinical characteristics and preference but also in vascular patrimony. As such, ultrasound evaluation aids in characterizing patient arterial and venous upper arm anatomy and provides information for which access would better suit each patient. Doctors dealing with CKD patients should be familiar with the role of ultrasound and Doppler use in access planning.

Ultrasound speckle tracking to detect vascular distensibility changes from angioplasty and branch ligation in a radio-cephalic fistula: Use of novel open source software

We used novel open source software, based on an ultrasound speckle tracking algorithm, to examine the distensibility of the vessel wall of the inflow artery, anastomosis, and outflow vein before and after two procedures. An 83-year-old white man with a poorly maturing radio-cephalic fistula received an angioplasty at the anastomosis followed by branch ligation 28 days later. Duplex Doppler measurements corroborated the blood flow related changes anticipated from the interventions. The experimental distensibility results showed that it is technically feasible to measure subtle vessel wall motion changes with high resolution (sub-millimeter) using standard Digital Imaging and Communications in Medicine (DICOM) ultrasound data, which are readily available on conventional ultrasound scanners. While this methodology was originally developed using high resolution radiofrequency from ultrasound data, the goal of this study was to use DICOM data, which makes this technology accessible to a wide range of users.

Impact of preoperative arterial and venous diameter on achievement of the adequate blood flow in arteriovenous fistula for hemodialysis

An arteriovenous fistula (AVF) remains the best choice of vascular access (VA) for hemodialysis (HD). The aim of the study was to determine the factors associated with the achievement of adequate blood flow (BF) of AVFs at the 4th week after creation. Created AVFs in 63 patients with chronic kidney disease (CKD) stage 4/5 and CKD stage 5 on hemodialysis (CKD5D) were analyzed in a prospective study. Doppler ultrasound (DUS) was used for measuring the diameter of the radial artery, the brachial artery and the cephalic vein before AVF creation. The BF of AVF was calculated by DUS at the 4th week after creation and adequate BF was defined as ≥ 600 mL/min. The average age of patients was 61.31 ± 12.9 years. An adequate BF of AVF at the 4th week after creation was achieved in 43.54% of patients. The BF of AVF measured in male patients was significantly higher compared to the BF of AVF obtained in females (576.03 mL/min vs 375.12 mL/min, P = 0.004). The diameter of the blood vessels with achieved adequate BF was significantly larger compared to the diameter of the blood vessels without adequate BF (radial artery: 2.45 mm vs 2.03 mm, P = 0.000; brachial artery: 4.78 mm vs 4.06 mm, P = 0.001 and cephalic vein: 3.12 mm vs 2.83 mm P =  0.018). The gender and the diameter of the blood vessels before AVF creation were significantly associated with achievement of adequate BF of AVF at the 4th week of creation.

Preoperative color Doppler ultrasound parameters for surgical decision-making in upper arm arteriovenous fistula maturation

OBJECTIVE

Current scientific evidence is insufficient to determine the best vascular access for each patient. It is an unmet clinical need because vascular access dysfunction accounts for 20% to 30% of hospital admissions. Our aim was to evaluate preoperative color flow Doppler ultrasound (CDUS)-derived parameters (vein diameter and brachial artery flow and diameter) and their effect interaction with comorbidities as predictors of brachiocephalic (BC) and brachiobasilic (BB) arteriovenous fistula (AVF) maturation.

METHODS

A prospective analysis was performed of patients who underwent BC and BB AVF as primary definitive vascular access between January 2016 and May 2017. Variables included patients' demographics, comorbidities, medication, preoperative blood pressure, and CDUS-derived parameters. Outcomes were patency 48 hours after surgery and fistula maturation at 6 and 12 weeks. Nonparametric descriptive and univariate statistics were used. Logistic regression models and receiver operating characteristic curve analyses were performed.

RESULTS

There were 132 patients (91 with BC AVF and 41 with BB AVF) included. The 48-hour patency was 91.7%. AVF maturation at 6 weeks was observed in 71.3%, and AVF maturation at 12 weeks was observed in 66.3%. There were no associations in univariate and multivariate logistic regression analysis between AVF maturation and comorbidities. Systolic blood pressure was an independent predictor of 48-hour patency with an optimized cutoff of 154 mm Hg (area under the curve, 0.73; P = .013; Youden index, 0.40). Vein diameter with tourniquet was an independent predictor of AVF maturation at 6 and 12 weeks with an optimized cutoff of 3.9 mm (area under the curve, 0.74; P < .001; Youden index, 0.38).

CONCLUSIONS

AVF maturation was independent of comorbidities. Systolic blood pressure ≥154 mm Hg and vein diameter with tourniquet ≥3.9 mm were the associated conditions that better predicted BC and BB AVF maturation. There were no effect interactions between CDUS-derived parameters and associated comorbidities.

Arteriovenous fistula maturation and the influence of fluid dynamics

Arteriovenous fistula creation is the preferred vascular access for haemodialysis therapy, but has a large failure rate in the maturation period. This period generally lasts 6 to 8 weeks after surgical creation, in which the vein and artery undergo extensive vascular remodelling. In this review, we outline proposed mechanisms for both arteriovenous fistula maturation and arteriovenous fistula failure. Clinical, animal and computational studies have not yet shown a definitive link between any metric and disease development, although a number of theories based on wall shear stress metrics have been suggested. Recent work allowing patient-based longitudinal studies may hold the key to understanding arteriovenous fistula maturation processes.

Efficacy and Safety of Ureteral Catheter Use During Arteriovenous Fistula in End-Stage Renal Disease Patients with Poor Vascular Status

Background

The aim of this study was to evaluate the efficacy and safety of use of a ureteral catheter during arteriovenous fistula in end-stage renal disease patients with poor vascular status.

Material/Methods

Fifty patients with standard arteriovenous fistulas at Sir Run Run Hospital of Nanjing Medical University from April 2018 to April 2019 were included. Based on the use of ureteral catheter exploration and tourniquet hydraulic dilatation, patients were divided into study and control groups. The operative success rate, inner diameter of cephalic vein 1 day post-operatively, blood flow in the internal fistula, patency rate and blood flow in the internal fistula 3 months post-operatively, and complications 6 months post-operatively were compared between the 2 groups.

Results

There were 25 cases in each group, with no significant differences in sex or age between the 2 groups. The operative success rate in the study group was higher than in the control group (96% vs. 88%) (F=1.087, P=0.297). The patency rates at 3 and 6 months post-operatively in the study group were higher than in the control group. The inner diameter of the cephalic vein 1 day post-operatively, the blood flow in the internal fistula, and the complications 6 months post-operatively in the study group were significantly superior to those of the control group (P=0.002).

Conclusions

In standard arteriovenous fistula, especially vascular catheter exploration of unhealthy vessels, the application of a ureteral catheter can improve the operative success rate and promote internal fistula maturity, with low cost and ease of use.

Reduced patency in left-sided arteriovenous grafts in a porcine model

OBJECTIVE

The porcine arteriovenous graft model is commonly used to study hemodialysis vascular access failure, with most studies using a bilateral, paired-site approach in either the neck or femoral vessels. In humans, left- and right-sided central veins have different anatomy and diameters, and left-sided central vein catheters have worse outcomes. We assessed the effect of laterality on arteriovenous prosthetic graft patency and hypothesized that left-sided carotid-jugular arteriovenous prosthetic grafts have reduced patency in the porcine model.

METHODS

Arteriovenous polytetrafluoroethylene grafts were placed ipsilaterally or bilaterally in 10 Yorkshire male pigs from the common carotid artery to the internal jugular vein. Ultrasound measurements of blood flow velocities and diameters were assessed before graft placement. Animals were sacrificed at 1 week, 2 weeks, or 3 weeks. Patency was determined clinically; grafts and perianastomotic vessels were excised and analyzed with histology and immunostaining.

RESULTS

At baseline, left- and right-sided veins and arteries had similar blood flow velocities. Although internal jugular veins had similar diameters at baseline, left-sided carotid arteries had 11% smaller outer diameters (P = .0354). There were 10 left-sided and 8 right-sided polytetrafluoroethylene grafts placed; only 4 of 10 (40%) grafts were patent on the left compared with 7 of 8 (88%) grafts patent on the right (P = .04). Left-sided grafts had increased macrophages at the arterial anastomosis (P = .0007). Left-sided perianastomotic arteries had thicker walls (0.74 vs 0.60 mm; P = .0211) with increased intima-media area (1.14 vs 0.77 mm²; P = .0169) as well as a trend toward 38% smaller luminal diameter (1.6 vs 2.5 mm; P = .0668) and 20% smaller outer diameter (3.0 vs 3.7 mm; P = .0861). Left- and right-sided perianastomotic veins were similar histologically, but left-sided veins had decreased expression of phosphorylated endothelial nitric oxide synthase (P = .0032) and increased numbers of α-actin-positive smooth muscle cells (P = .0022).

CONCLUSIONS

Left-sided arteriovenous grafts are associated with reduced short-term patency compared with right-sided grafts in the Yorkshire pig preclinical model of arteriovenous prosthetic grafts. Laterality must be considered in planning and interpreting surgical preclinical models.

Arteriovenous conduits for hemodialysis: how to better modulate the pathophysiological vascular response to optimize vascular access durability

Vascular access is the lifeline for patients on hemodialysis. Arteriovenous fistulas (AVFs) are the preferred vascular access, but AVF maturation failure remains a significant clinical problem. Currently, there are no effective therapies available to prevent or treat AVF maturation failure. AVF maturation failure frequently results from venous stenosis at the AVF anastomosis, which is secondary to poor outward vascular remodeling and excessive venous intimal hyperplasia that narrows the AVF lumen. Arteriovenous grafts (AVGs) are the next preferred vascular access when an AVF creation is not possible. AVG failure is primarily the result of venous stenosis at the vein-graft anastomosis, which originates from intimal hyperplasia development. Although there has been advancement in our knowledge of the pathophysiology of AVF maturation and AVG failure, this has not translated into effective therapies for these two important clinical problems. Further work will be required to dissect out the mechanisms of AVF maturation failure and AVG failure to develop more specific therapies. This review highlights the major recent advancements in AVF and AVG biology, reviews major clinical trials, and discusses new areas for future research.

Arteriovenous fistula and pre-surgery mapping: Potential role of physical exercise on endothelial function

Background:

The success of the construction of an arteriovenous fistula for haemodialysis is related to the vascular function of the vessels involved in the anastomosis, with particular reference to radial artery distensibility after reactive hyperaemia test and to the fall of resistance index. Only few studies have evaluated the impact of exercise protocols on the endothelial and morphological characteristics of the vessels of the upper limb with inconclusive results. In this pilot longitudinal study, we aimed to evaluate the impact of a standardized exercise protocol on the haemodynamic and resistive index of the arteries of the upper limb of uraemic patients.

Methods:

A total of 17 uraemic patients planned to construct arteriovenous fistula at the distal third of the forearm were enrolled and followed up for 30 days. All patients performed repeated handgrips for 30 min/day. The arterial parameters were detected before and after an ischaemic stress of 5 min and radial and brachial artery flow-mediated dilation was evaluated as well as radial artery resistance index.

Results:

Pre-exercise measurements of radial artery diameter and resistance index and brachial artery diameter were not modified by 30 days hand physical exercise, whereas the post-exercise haemodynamic were improved. Consequently, flow-mediated dilation of the radial artery was improved (21% ± 14% vs 30% ± 19%; p = 0.03) and resistance index of the radial artery was reduced ( p = 0.02).

Conclusion:

Exercise has beneficial effects on endothelial function of the radial artery by resistive index and, potentially, on the outcome of the arteriovenous fistula. Further studies with larger sample size are needed to confirm our preliminary data.

The effect of endothelial nitric oxide synthase on the hemodynamics and wall mechanics in murine arteriovenous fistulas

Creation of a hemodialysis arteriovenous fistula (AVF) causes aberrant vascular mechanics at and near the AVF anastomosis. When inadequately regulated, these aberrant mechanical factors may impede AVF lumen expansion to cause AVF maturation failure, a significant clinical problem with no effective treatments. The endothelial nitric oxide synthase (NOS3) system is crucial for vascular health and function, but its effect on AVF maturation has not been fully characterized. We hypothesize that NOS3 promotes AVF maturation by regulating local vascular mechanics following AVF creation. Here we report the first MRI-based fluid-structure interaction (FSI) study in a murine AVF model using three mouse strains: NOS3 overexpression (NOS3 OE) and knockout (NOS3-/-) on C57BL/6 background, with C57BL/6 as the wild-type control (NOS3+/+). When compared to NOS3+/+ and NOS3-/-, AVFs in the OE mice had larger lumen area. AVFs in the OE mice also had smoother blood flow streamlines, as well as lower blood shear stress at the wall, blood vorticity, inner wall circumferential stretch, and radial wall thinning at the anastomosis. Our results demonstrate that overexpression of NOS3 resulted in distinct hemodynamic and wall mechanical profiles associated with favorable AVF remodeling. Enhancing NOS3 expression may be a potential therapeutic approach for promoting AVF maturation.

Careful Patient Selection Achieves High Radiocephalic Arteriovenous Fistula Patency in Diabetic and Female Patients

BACKGROUND

The radiocephalic arteriovenous fistula (rcAVF) is considered the first-choice site for hemodialysis access; however, it has been associated with decreased rates of patency and maturation in women and diabetic patients in some studies. We hypothesized that careful preoperative selection of patients for an rcAVF fistula would result in a high 1-year patency rate and that external factors, such as female gender and diabetes mellitus (DM), would not adversely affect fistula patency.

METHODS

This is a retrospective study of all patients who underwent rcAVF creation at a single institution from January 2011 to June 2016. Patients were carefully selected based on clinical examination and preoperative, B-mode, ultrasound findings. Primary patency and primary assisted patency at 1 year were calculated. Survival analysis was also conducted to evaluate for factors associated with rcAVF patency.

RESULTS

There were 158 patients identified who underwent rcAVF fistula creation and were seen in follow-up. The 1-year primary and primary assisted patency rates were 62% and 81%, respectively. On Kaplan-Meier survival analysis, there was no difference in rcAVF patency with respect to gender, Hispanic race, anesthesia type, DM, and smoking status. Patients with a prior AVF, most often received in the nondominant arm and now receiving an rcAVF in the dominant arm, had a significantly higher risk of fistula failure, in both primary and primary assisted patency survival (hazard ratio 5.1, 95% confidence interval 1.6-16.2, P = 0.06). Patients without a history of hypertension (HTN), as noted in the electronic medical records, trended toward a higher risk of primary assisted patency rcAVF failure, compared to those who had a history of HTN (hazard ratio 3.0, 95% confidence interval 1.1-7.9, P = 0.03).

CONCLUSIONS

With careful patient selection, the rcAVF can achieve a high 1-year primary assisted patency rate. Female gender and DM were not significantly associated with an increase in rcAVF failure and should not be heavily relied on in-patient selection. First-time AVF patients and patients with a history of HTN may be associated with increased rcAVF patency.

The effect of stellate ganglion block on the function of arteriovenous fistulas for hemodialysis: A randomized trial

BACKGROUND AND PURPOSE

The best access for hemodialysis is an autologous arteriovenous fistula (AVF). The most helpful way for vasodilation in the upper limb is stellate ganglion block. We aim to evaluate the effect of stellate ganglion block on outcome of vascular access for dialysis.

MATERIALS AND METHODS

Some 105 hemodialysis patients were randomly allocated to three groups: In group 1, stellate ganglion block was performed before fistula surgery. Group 2 had stellate ganglion block after surgery and group 3 was control group without any block. Primary outcome for all groups was functional dialysis, which is defined as successful hemodialysis for 1 month.

RESULTS

The three groups were similar in age, gender, and underlying diseases. Stellate ganglion block before operation had a meaningful increase in successful hemodialysis rate, when compared with the other groups (p = 0.02).

CONCLUSION

Stellate ganglion block before arteriovenous fistula surgery in the upper limbs improves hemodialysis success rate.

Correlation between preoperative vein and artery diameters and arteriovenous fistula outcome in patients with end-stage renal disease

BACKGROUND AND AIMS

Arteriovenous fistula (AVF) maturation failure rates remain high in patients with end-stage renal disease (ESRD). Although preoperative morphological and functional assessment of blood vessels by duplex ultrasonography (DUS) has been shown to improve AVF maturation, there is no consensus regarding the optimal vein (VD) and artery (AD) diameters to be universally used for AVF creation. To improve patient selection, set out to investigate if there is a correlation between preoperative VD/AD and clinical covariates, and postoperative AVF outcome.

METHODS

This was a prospective cohort study conducted during January-August 2014. ESRD patients referred to "Niculae Stăncioiu" Heart Institute Cluj-Napoca, who had a VD ≥1.9 mm and AD ≥1.5 mm, as measured by DUS, and underwent AVF creation were enrolled. We assessed whether preoperative VD/AD and clinical covariates were associated with AVF maturation rate and primary patency at 2 years after AVF creation.

RESULTS

Of 115 patients referred for AVF creation, 93 were included in the study. Mean (± standard deviation) VD was 3.3 ± 1.1 mm and VDs were distributed in quartile Q1 <2.55 mm, Q2: 2.56-3.10 mm, Q3: 3.11-3.70 mm and Q4: >3.71 mm. Mean AD was 3.3 ± 1.4 mm and ADs were distributed in Q1 <2.55 mm, Q2: 2.56-3.10 mm, Q3: 3.11-3.70 mm, and Q4, >3.71 mm. AVF maturation rate increased proportionally with VD from Q1 (62%) to Q2 (70%), Q3 (82%) to Q4 (96%) (p=0.03). Based on AD, a higher AVF maturation rate was observed in Q3 (86%), Q4 (83%) vs Q1 (71%) and Q2 (67%). Long-term primary patency of AVFs seemed not to be influenced by VD and AD. In older patients and those with peripheral arterial disease, AVF maturation failure tended to be higher.

CONCLUSIONS

Our findings suggest that a preoperative VD ≥1.9 mm and AD ≥1.5 mm have a successful maturation rate of AVF greater than 60% in ESRD patients. The maturation rate of surgical AVF increases proportionally with the size of VD used for AVF creation.

Spanish Clinical Guidelines on Vascular Access for Haemodialysis

Vascular access for haemodialysis is key in renal patients both due to its associated morbidity and mortality and due to its impact on quality of life. The process, from the creation and maintenance of vascular access to the treatment of its complications, represents a challenge when it comes to decision-making, due to the complexity of the existing disease and the diversity of the specialities involved. With a view to finding a common approach, the Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology [S.E.N.], vascular surgery [SEACV], vascular and interventional radiology [SERAM-SERVEI], infectious diseases [SEIMC] and nephrology nursing [SEDEN]), along with the methodological support of the Cochrane Center, has updated the Guidelines on Vascular Access for Haemodialysis, published in 2005. These guidelines maintain a similar structure, in that they review the evidence without compromising the educational aspects. However, on one hand, they provide an update to methodology development following the guidelines of the GRADE system in order to translate this systematic review of evidence into recommendations that facilitate decision-making in routine clinical practice, and, on the other hand, the guidelines establish quality indicators which make it possible to monitor the quality of healthcare.

Association of Preoperative Mean Arterial Pressure With the Primary Failure of Brescia-Cimino Arteriovenous Fistula Within the First 7 Days Following Surgery in Hemodialysis Patients

This retrospective study included 1051 patients with end-stage kidney disease and Brescia-Cimino arteriovenous fistula (AVF) (excluding pre-dialysis patients), and aimed to investigate the role of blood pressure in AVF primary failure. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured twice daily for 3 days before surgery. The success (N = 1010) and failure (N = 41) groups were based on AVF primary failure within 7 days of surgery. The cephalic vein was larger and the preoperative mean arterial pressure (MAP) was higher in the success group compared with the failure group (P < 0.05). Cephalic vein diameter and preoperative MAP independently predicted AVF primary failure within 7 days after surgery. In conclusion, small cephalic vein diameter and low preoperative MAP were associated with AVF primary failure within 7 days of surgery.

A pilot study to measure vascular compliance changes during fistula maturation using open-source software

PURPOSE:

Autogenous arteriovenous fistulas are the preferred access for hemodialysis. Yet when created, fistulas often fail to mature, requiring surgical or radiologic interventions before their use. This pilot study measures the vascular wall elasticity and flow gradient using an open-source ultrasound software program designed to aid in assessing fistula maturation.

METHODS:

A total of seven end-stage renal disease patients were enrolled for our study after providing informed consent. Ultrasound scanning was performed for the inflow artery, post-arterial anastomotic segment, and outflow vein at initial and follow-up evaluation. Conventional digital imaging and communications in medicine data were collected from the ultrasound machine. The vessel diameter and distensibility of artery, post-arterial anastomotic segment, and vein were computed from the digital imaging and communications in medicine data using an open-source ultrasound software program.

RESULTS:

The vessel diameter of artery and vein increased from 4.6 ± 1.1 mm to 6.0 ± 1.1 mm and from 5.8 ± 0.7 mm to 7.5 ± 0.9 mm from 1 to 6 weeks post-operation, respectively. Conversely, the vessel diameter of post-arterial anastomotic segment decreased from 4.2 ± 1.0 mm to 3.5 ± 0.9 mm from 1 to 6 weeks post-operation. The distensibility of artery and post-arterial anastomotic segment increased from 3.4% ± 0% to 5.9% ± 1.1% and 3.7% ± 1.2% to 4.9% ± 1.4%, respectively, while the distensibility of vein decreased from 5.0% ± 1.3% to 2.6% ± 0.4% from 1 to 6 weeks post-operation.

CONCLUSION:

This study demonstrates that the change in vessel diameter and distensibility related to the healthy remodeling as the vein dilates during maturation.

A Meta-analysis of Preoperative Duplex Ultrasound Vessel Diameters for Successful Radiocephalic Fistula Placement

Background

The Kidney Dialysis Outcomes Quality Initiative (K/DOQI) guidelines for vascular access recommend the use of radiocephalic wrist arteriovenous fistulas (RCAVFs) as the initial option for dialysis access. The survival rate of a successfully placed fistula is excellent. However, 10–24% of RCAVFs fail to reach functional status as the result of early thrombosis or maturation failure. Many authors have investigated the utility of preoperative vascular mapping by Duplex ultrasound to predict adequate vessel size for successful fistula placement. This meta-analysis is the first in which preoperative radial arterial (RAD) and cephalic venous diameters (CVD) required for favorable fistula outcomes are reviewed.

Methods

A literature search was performed by use of the MEDLINE electronic base for “arteriovenous, fistula, ultrasound, and hemodialysis.” The analysis yielded 166 studies, of which 20 studies included preoperative duplex data. Meta-analysis was performed by applying the statistical test of comparing two proportions, assuming equal variances.

Results

A total of 433 patients were duplexed for preoperative evaluation of the RAD and 386 for CVD. The total number of subjects ranged from 21 to 91, mean age 58.7 years. The subjects were 55.5% male, 39.0% with diabetes mellitus. Meta-analysis yielded 2.0 mm for RAD and 2.0 mm for CVD as designated cutoff vessel diameters. Our study showed the mean fistula success rate was significantly different between RAD >2.0 mm (59%) and RAD >2.0 mm (40%). The mean fistula success rate was also significantly different between CVD > 2.0 mm (71%) and >2.0 mm (29%). Successful fistula placement was defined as a functional fistula at least 4–6 weeks after creation.

Conclusion

On the basis of our study, the use of Duplex ultrasound is important in determining preoperative vessel diameter size, and subsequent functional success rate of fistula placement.

Less primary fistula failure in hypertensive patients

End stage renal disease (ESRD) patients suffer from advanced renal diseases and actually nonfunctioning kidneys, and need kidney transplantation or dialysis. Hemodialysis (HD) is the most used method and requires a vascular access (VA). Arteriovenous fistula (AVF) is the first choice of VA over the world for having least morbidity and mortality. Despite the wide-spread use of AVFs, the rate of AVF failures are notable. Detecting the factors that cause AVF failure can reduce repeating VA surgeries and hospitalization of ESRD patients. Present research studies 480 Iranian HD patients who underwent AVF surgery from 2010 to 2017 and aged 18-90 years old, using data mining techniques. (i) The AVF failure rate was equal to 8.96%, such that AVF failure has occurred in 3.54% and 5.52% of HD patient with and without hypertension, respectively. (ii) The rate of non-failure AVF in hypertensive patients is 61.46%, whereas the same rate for patients with negative history of hypertension reaches to 29.58%. (iii) Hypertension has a significant inverse association with AVF failure (Spearman's ρ = -0.160, P-value ≤ 0.005). (iv) The decision tree (with accuracy rate = 92.24%) shows less AVF failure in hypertsensive patients (5.53%) comparing with non-hypertensive patients (15.09%). (v) The AVFs with greater failure rates and non-hypertensive HD patients were clustered together. "Significantly lower risk of AVF failure was associated with presence of a positive history of hypertension; in other words, positive history of hypertension has an adverse effect on AVF failure and Hypertensive HD patients have more maturated AVF."

Factors Associated with Early Thrombosis after Arteriovenous Fistula Creation

BACKGROUND

Arteriovenous fistulas (AVF) are the preferred modality for hemodialysis access. Early thrombosis hampers development of a working AVF. We endeavored to determine the incidence and identify factors associated with early thrombosis of AVF and to determine salvage rates following thrombosis, at a high-volume hemodialysis access center.

METHODS

Retrospective review of autologous AVF was created between November 2014 and July 2016 at a single center. Early thrombosis was defined as thrombosis that occurred within 30 days of surgery.

RESULTS

There were 291 AVFs. The median age was 54.7 years, and 192 patients (66%) were male. Early postoperative AVF thrombosis was noted in 5 (1.7%) cases. Factors associated with early thrombosis on univariate analysis included previous access surgery (P = 0.02) and absence of a good intraoperative thrill (P = 0.006). Intraoperative protamine use trended toward significance (P = 0.06). Factors that were not significant included gender, diabetes, dialysis at time of surgery, fistula configuration, and systemic heparin use. None of the thrombosed fistulas were salvaged.

CONCLUSIONS

Early thrombosis is a relatively rare complication of AVF creation at a high-volume center. Previous access surgery and absence of good thrill at conclusion of the procedure are associated with early thrombosis.

Imaging in Vascular Access

This review examines four imaging modalities; ultrasound (US), digital subtraction angiography (DSA), magnetic resonance imaging (MRI) and computed tomography (CT), that have common or potential applications in vascular access (VA). The four modalities are reviewed under their primary uses, techniques, advantages and disadvantages, and future directions that are specific to VA. Currently, US is the most commonly used modality in VA because it is cheaper (relative to other modalities), accessible, non-ionising, and does not require the use of contrast agents. DSA is predominantly only performed when an intervention is indicated. MRI is limited by its cost and the time required for image acquisition that mainly confines it to the realm of research where high resolution is required. CT’s short acquisition times and high resolution make it useful as a problem-solving tool in complex cases, although accessibility can be an issue. All four imaging modalities have advantages and disadvantages that limit their use in this particular patient cohort. Current imaging in VA comprises an integrated approach with each modality providing particular uses dependent on their capabilities. MRI and CT, which currently have limited use, may have increasingly important future roles in complex cases where detailed analysis is required.

An Open-Source Ultrasound Software for Diagnosis of Fistula Maturation

Vascular access is essential for hemodialysis patients. The mature native arteriovenous fistula has been the preferred vascular access for hemodialysis, because it has greater longevity than synthetic grafts. However, once surgically created, fistulas often fail to develop (mature) into viable points of vascular access, requiring surgical or radiologic interventions before their use. Because maturation depends on vascular mechanics (e.g., distensibility and wall shear), we developed open-source ultrasound software to investigate these metrics clinically. We demonstrated in a single patient the ability of the software for consistent measurements from various locations within a cardiac cycle and between different cardiac cycles. We further assessed the ability of the software to identify changes in distensibility of a patient's fistula from 1 to 6 weeks postoperation. The routine frame rates of clinical machines demonstrated high fidelity tracking within cardiac cycles (coefficient of variation [CV] = 2.4% ± 0.011) and between cardiac cycles (CV = 2.4% ± 0.004). The distensibility of the patient's fistula from 1 to 6 weeks postoperation increased from 4% to 7% in the arterial inflow and from 3% to 4% in the postarterial anastomotic segment (PAAS). In contrast, the distensibility of the outflow vein decreased from 4% to 2%. These results corroborate that in addition to diameter changes, the mechanical properties of the vascular segments changed during fistula maturation. This demonstrates that our software-based approach may allow ultrasound-based mechanical measurements to become more accessible for wider clinical research.

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.

The Significance of Inflow Artery and Tourniquet Derived Cephalic Vein Diameters on Predicting Successful Use and Patency of Arteriovenous Fistulas for Haemodialysis

OBJECTIVE

To investigate the significance of inflow artery and cephalic vein diameters on predicting patency of radiocephalic and brachiocephalic arteriovenous fistulas (AVFs).

DESIGN

Single centre study with retrospective analysis of prospectively collected data between November 2010 and July 2015.

METHODS

A detailed history and physical examination was undertaken, including age, gender, history and duration of haemodialysis, cause of chronic kidney disease, and the presence of comorbidities/risk factors. Pre-operative arterial and venous upper extremity mapping was performed and inner vessel diameter was recorded, using a tourniquet for the veins. Outcome measures included AVF use (functionality), primary, primary assisted, secondary, and functional secondary patency.

RESULTS

One hundred and thirty five AVFs (57 and 78 radiocephalic and brachiocephalic AVFs, respectively) were constructed and followed up for 5 years. A cephalic vein diameter <4.3 mm (lower three quartiles) was the single independent predictor of inferior secondary and also functional secondary patency of radiocephalic AVFs (p = .02, HR 11.2, 95% CI 1.44-90.9). A brachial artery diameter ≤4.1 mm (lowest quartile) was an independent predictor of AVF functionality (57% vs. 83% for larger arteries, p = .017), and inferior primary, primary assisted, secondary, and functional secondary patency of brachiocephalic AVFs (primary assisted patency 21.9% vs. 55.9% at 3 years, p = .001/log-rank test, HR 3.1, p = .002/Cox regression). The presence of lower extremity PAD or use of dual antithrombotics was also independently associated with an inferior secondary patency. The number of risk factors (brachial artery diameter ≤4.1 mm, PAD, and use of dual antithrombotics) demonstrated risk stratification capabilities for functional secondary patency.

CONCLUSIONS

Among patients undergoing radiocephalic AVFs, a tourniquet derived cephalic vein diameter <4.3 mm was the single independent predictor of inferior secondary and functional secondary patency. Among patients undergoing brachiocephalic AVFs, all patency rates were inferior in the presence of a brachial artery diameter ≤4.1 mm and secondary patency was inferior in the presence of multiple risk factors.

Multiple preoperative and intraoperative factors predict early fistula thrombosis in the Hemodialysis Fistula Maturation Study

OBJECTIVE

Early thrombosis (ET) contributes to autogenous arteriovenous fistula (AVF) failure. We studied patients undergoing AVF placement in the Hemodialysis Fistula Maturation Study, a prospective, observational cohort study, using a nested case-control analysis to identify preoperative and intraoperative predictors of ET.

METHODS

ET cases were compared with controls, who were matched for gender, age, diabetes, dialysis status, and surgeon fistula volume. ET was defined as thrombosis diagnosed by physical examination or ultrasound within 18 days of AVF creation. Conditional logistic regression models were fit to identify risk factors for ET.

RESULTS

Thirty-two ET cases (5.3%) occurred among 602 study participants; 198 controls were matched. ET was associated with female gender (odds ratio [OR], 2.75; 95% confidence interval [CI], 1.19-6.38; P = .018), fistula location (forearm vs upper arm; OR, 2.76; 95% CI, 1.05-7.23; P = .039), feeding artery (radial vs brachial; OR, 2.64; 95% CI, 1.03-6.77; P = .043) and arterial diameter (OR, 1.52; 95% CI, 1.02-2.26; P = .039, per mm smaller). The draining vein diameter was nonlinearly associated with ET, with highest risk in 2- to 3-mm veins. Surprisingly, ET risk was lower in diabetics (OR, 0.19; 95% CI, 0.07-0.47; P = .0004), lower with less nitroglycerin-mediated brachial artery dilation (OR, 0.42; 95% CI, 0.20-1.92; P = .029 for each 10% lower) and higher with lower carotid-femoral pulse wave velocity (OR, 1.49; 95% CI, 1.02-2.20; P = .041, for each m/s lower). Intraoperative protamine use was associated with a higher ET risk (OR, 3.26; 95% CI, 1.28-∞; P = .038). Surgeon's intraoperative perceptions were associated with ET: surgeons' greater concern about maturation success (likely, marginal, unlikely) was associated with higher thrombosis risk (OR, 8.09; 95% CI, 4.03-∞; P < .0001, per category change), as were absence vs presence of intraoperative thrill (OR, 21.0; 95% CI, 5.07-∞; P = .0001) and surgeons' reported frustration during surgery (OR, 6.85; 95% CI, 2.70-∞; P = .0004). Decreased extent of intraoperative thrill (proximal, mid or distal third of the forearm or upper arm, based on AVF placement) was also associated with ET (OR, 2.91; 95% CI, 1.31-∞; P = .007, per diminished level). Oral antithrombotic medication use was not significantly associated with ET.

CONCLUSIONS

ET was found to be associated with female gender, forearm AVF, smaller arterial size, draining vein diameter of 2 to 3 mm, and protamine use. Paradoxically, diabetes and stiff, noncompliant feeding arteries were associated with a lower frequency of ET. Absent or attenuated intraoperative thrill, and both surgeon frustration and concern about successful maturation during surgery, were correlated strongly with ET.