Early Predictors of Arteriovenous Fistula Maturation: A Novel Perspective on an Enduring Problem

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.

Challenges of Predicting Arteriovenous Access Survival Prior to Conversion from Catheter

OBJECTIVE

The decision to convert from catheter to arteriovenous access is difficult yet very important. The ability to accurately predict fistula survival prior to surgery would significantly improve the decision making process. Many previously investigated demographic and clinical features have been associated with fistula failure. However, it is not conclusively understood how reliable predictions based on these parameters are at an individual level. The aim of this study was to investigate the probability of arteriovenous fistula maturation and survival after conversion using machine learning workflows.

METHODS

A retrospective cohort study on multicentre data from a large North American dialysis organisation was conducted. The study population comprised 73 031 chronic in centre haemodialysis patients. The dataset included 49 variables including demographic and clinical features. Two distinct feature selection and prediction pipelines were used: LASSO regression and Boruta followed by a random forest classifier. Predictions were facilitated for re-conversion to catheter within one year. Additionally, all cause mortality predictions were conducted to serve as a comparator.

RESULTS

In total, 38 151 patients (52.2%) had complete data and made up the main cohort. Sensitivity analyses were conducted in 67 421 patients (92.3%) after eliminating variables with a high proportion of missing data points. Selected features diverged between datasets and workflows. A previously failed arteriovenous access appeared to be the most stable predictor for subsequent failure. Prediction of re-conversion based on the demographic and clinical information resulted in an area under the receiver operating characteristic curve (ROCAUC) between 0.541 and 0.571, whereas models predicting all cause mortality performed considerably better (ROCAUC 0.662 - 0.683).

CONCLUSION

While group level depiction of major adverse outcomes after catheter to arteriovenous fistula or graft conversion is possible using the included variables, patient level predictions are associated with limited performance. Factors during and after fistula creation as well as biomolecular and genetic biomarkers might be more relevant predictors of fistula survival than baseline clinical conditions.

Doppler ultrasound surveillance of recently formed haemodialysis arteriovenous fistula: the SONAR observational cohort study

Background

Arteriovenous fistulas are considered the best option for haemodialysis provision, but as many as 30% fail to mature or suffer early failure.

Objective

To assess the feasibility of performing a randomised controlled trial that examines whether, by informing early and effective salvage intervention of fistulas that would otherwise fail, Doppler ultrasound surveillance of developing arteriovenous fistulas improves longer-term arteriovenous fistula patency.

Design

A prospective multicentre observational cohort study (the 'SONAR' study).

Setting

Seventeen haemodialysis centres in the UK.

Participants

Consenting adults with end-stage renal disease who were scheduled to have an arteriovenous fistula created.

Intervention

Participants underwent Doppler ultrasound surveillance of their arteriovenous fistulas at 2, 4, 6 and 10 weeks after creation, with clinical teams blinded to the ultrasound surveillance findings.

Main outcome measures

Fistula maturation at week 10 defined according to ultrasound surveillance parameters of representative venous diameter and blood flow (wrist arteriovenous fistulas: ≥ 4 mm and > 400 ml/minute; elbow arteriovenous fistulas: ≥ 5 mm and > 500 ml/minute). Mixed multivariable logistic regression modelling of the early ultrasound scan data was used to predict arteriovenous fistula non-maturation by 10 weeks and fistula failure at 6 months.

Results

A total of 333 arteriovenous fistulas were created during the study window (47.7% wrist, 52.3% elbow). By 2 weeks, 37 (11.1%) arteriovenous fistulas had failed (thrombosed), but by 10 weeks, 219 of 333 (65.8%) of created arteriovenous fistulas had reached maturity (60.4% wrist, 67.2% elbow). Persistently lower flow rates and venous diameters were observed in those fistulas that did not mature. Models for arteriovenous fistulas' non-maturation could be optimally constructed using the week 4 scan data, with fistula venous diameter and flow rate the most significant variables in explaining wrist fistula maturity failure (positive predictive value 60.6%, 95% confidence interval 43.9% to 77.3%), whereas resistance index and flow rate were most significant for elbow arteriovenous fistulas (positive predictive value 66.7%, 95% confidence interval 48.9% to 84.4%). In contrast to non-maturation, both models predicted fistula maturation much more reliably [negative predictive values of 95.4% (95% confidence interval 91.0% to 99.8%) and 95.6% (95% confidence interval 91.8% to 99.4%) for wrist and elbow, respectively]. Additional follow-up and modelling on a subset (n = 192) of the original SONAR cohort (the SONAR-12M study) revealed the rates of primary, assisted primary and secondary patency arteriovenous fistulas at 6 months were 76.5, 80.7 and 83.3, respectively. Fistula vein size, flow rate and resistance index could identify primary patency failure at 6 months, with similar predictive power as for 10-week arteriovenous fistula maturity failure, but with wide confidence intervals for wrist (positive predictive value 72.7%, 95% confidence interval 46.4% to 99.0%) and elbow (positive predictive value 57.1%, 95% confidence interval 20.5% to 93.8%). These models, moreover, performed poorly at identifying assisted primary and secondary patency failure, likely because a subset of those arteriovenous fistulas identified on ultrasound surveillance as at risk underwent subsequent successful salvage intervention without recourse to early ultrasound data.

Conclusions

Although early ultrasound can predict fistula maturation and longer-term patency very effectively, it was only moderately good at identifying those fistulas likely to remain immature or to fail within 6 months. Allied to the better- than-expected fistula patency rates achieved (that are further improved by successful salvage), we estimate that a randomised controlled trial comparing early ultrasound-guided intervention against standard care would require at least 1300 fistulas and would achieve only minimal patient benefit.

Trial Registration

This trial is registered as ISRCTN36033877 and ISRCTN17399438.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR135572) and is published in full in Health Technology Assessment; Vol. 28, No. 24. See the NIHR Funding and Awards website for further award information.

The difference in diameter between radial artery and cephalic vein correlates with primary patency of radio-cephalic arteriovenous fistula

INTRODUCTION

Autogenous radio-cephalic arteriovenous fistula (RCAVF) is preferred for chronic hemodialysis access. However, RCAVF still suffers from disappointing survival due to fistula dysfunction, with intimal hyperplasia (IH) as an underlying cause of this condition. The inconsistency of radial artery diameter (DRA) and cephalic vein diameter (DCV) is one of the factors affecting the shear disturbance, which is believed to trigger the onset of IH. However, there are no reports correlating the difference in DRA and DCV with RCAVF outcomes.

METHODS

This was a retrospective cohort study. Consecutive patients (n = 233) with a new RCAVF created were included if they underwent duplex ultrasound examination to evaluate preoperatively the radial artery diameter (DRA) and cephalic venous diameter (DCV). We then calculated radial artery-cephalic vein diameter difference (DCV minus DRA, termed DCV-DRA hereafter) and evaluated the association of the preoperative DCV-DRA with primary patency of RCAVF at 12 months. Subgroup analysis was also performed to explore effect modification by age, gender, radial artery diameter, and cephalic vein diameter with DCV-DRA.

RESULTS

After adjusting for age, gender, weight, and mean arterial pressure, the preoperative DCV-DRA was associated with primary patency of RCAVF at 12 months (adjusted Odds ratio [aOR], 1.524 per 1-mm increase; 95% confidence interval [95% CI], 1.048-2.218). The primary patency of RCAVF at 12 months was achieved in 69.4%, 71.8%,and 87.3% of patients with a preoperative DCV-DRA of ⩽-0.6 mm, (-0.5)-0.5 mm, and ⩾0.6 mm, respectively. P for trend was 0.029. Patients with DCV-DRA of ⩾0.6 mm had a much higher chance of 12-month patency than patients with DCV-DRA of ⩽-0.6 mm (aOR, 3.574; 95% CI, 1.276-10.010). Age, gender, radial artery diameter, and cephalic vein diameter did not modify the association of DCV-DRA with primary patency of RCAVF at 12 months.

CONCLUSIONS

Preoperative DCV-DRA may be an under-recognized predictor of RCAVF patency.

Association between heart failure and arteriovenous access patency in patients with end-stage renal disease on hemodialysis

BACKGROUND

Heart disease and chronic kidney disease are often comorbid conditions owing to shared risk factors, including diabetes and hypertension. However, the effect of congestive heart failure (CHF) on arteriovenous fistula (AVF) and AV graft (AVG) patency rates is poorly understood. We hypothesize preexisting HF may diminish blood flow to the developing AVF and worsen patency.

METHODS

We conducted a single-institution retrospective review of 412 patients with end-stage renal disease who underwent hemodialysis access creation from 2015 to 2021. Patients were stratified based on presence of preexisting CHF, defined as clinical symptoms plus evidence of reduced left ventricular ejection fraction (EF) (<50%) or diastolic dysfunction on preoperative echocardiography. Baseline demographics, preoperative measures of cardiac function, and dialysis access-related surgical history were collected. Kaplan-Meier time-to-event analyses were performed for primary patency, primary-assisted patency, and secondary patency using standard definitions for patency from the literature. We assessed differences in patency for patients with CHF vs patients without CHF, patients with a reduced vs a normal EF, and AVG vs AVF in patients with CHF.

RESULTS

We included 204 patients (50%) with preexisting CHF with confirmatory echocardiography. Patients with CHF were more likely to be male and have comorbidities including, diabetes, chronic obstructive pulmonary disease, hypertension, and a history of cerebrovascular accident. The groups were not significantly different in terms of prior fistula history (P = .99), body mass index (P = .74), or type of hemodialysis access created (P = .54). There was no statistically significant difference in primary patency, primary-assisted patency, or secondary patency over time in the CHF vs non-CHF group (log-rank P > .05 for all three patency measures). When stratified by preoperative left ventricular EF, patients with an EF of <50% had lower primary (38% vs 51% at 1 year), primary-assisted (76% vs 82% at 1 year), and secondary patency (86% vs 93% at 1 year) rates than those with a normal EF. Difference reached significance for secondary patency only (log-rank P = .029). AVG patency was compared against AVF patency within the CHF subgroup, with significantly lower primary-assisted (39% vs 87% at 1 year) and secondary (62% vs 95%) patency rates for AVG (P < .0001 for both).

CONCLUSIONS

In this 7-year experience of hemodialysis access creation, reduced EF is associated with lower secondary patency. Preoperative CHF (including HF with reduced EF and HF with preserved EF together) is not associated with significant differences in overall hemodialysis access patency rates over time, but patients with CHF who receive AVG have markedly worse patency than those who receive AVF. For patients with end-stage renal disease and CHF, the risks and benefits must be carefully weighed, particularly for those with low EF or lack of a suitable vein for fistula creation.

Predicting factors for early failure of vascular access in hemodialysis patients

Purpose

This study aimed to investigate the incidence of early failure of vascular access for hemodialysis, and determine which factors measured in duplex ultrasound study could predict early failure.

Methods

We performed a retrospective review of patients who underwent arteriovenous fistula (AVF) or arteriovenous graft (AVG) creation for hemodialysis between September 2019 and January 2023. Early failure was defined as any event that required surgical or endovascular intervention within 6 months following AVF or AVG creation.

Results

A total of 189 patients were included. Early failure occurred in 36 patients (19.0%), which included 22 AVFs and 14 AVGs. In the patients who underwent AVF, the preoperative venous diameter, postoperative venous and arterial diameters, and flow volume of AVF all were significantly smaller in the early failure group compared to the patent group. In AVG, the preoperative venous diameter was the only parameter that differed between the 2 groups. A sonographic score was defined based on these factors. In a multivariable analysis, male sex, a previous history of AVF or AVG creation, and sonographic score were found to be significantly associated with early failure. The postoperative venous diameter in AVF and the preoperative venous diameter in AVG were highly predictive of early failure (areas under the curves 0.92 and 0.82, respectively).

Conclusion

Venous diameter measured 6 weeks following AVF operation and preoperative venous diameter in AVG were highly predictive of early failure among the duplex ultrasound parameters. Surveillance strategies in the early phase following vascular access creation can be based on these factors.

Comparing post-maturation outcomes of arteriovenous grafts and fistulae

BACKGROUND

Though arteriovenous grafts (AVG) mature more reliably than arteriovenous fistulae (AVF) and require fewer maturation procedures (MP) to obtain functional patency, AVG are thought to have worse function after maturation. We explored differences in post-maturation outcomes between the following groups: AVF patients who did (AS-AVF) and did not (unAS-AVF) require assisted maturation and AVG patients who did (AS-AVG) and did not (unAS-AVG) require assisted maturation.

METHODS

Using the US Renal Data System (2012-2017), we retrospectively identified patients who initiated dialysis with a central venous catheter, underwent AVF or AVG placement and achieved successful two-needle cannulation. Primary patency and access abandonment after maturation were compared across groups using competing risks regression methods, generating sub-hazards ratios (sHR).

RESULTS

We identified 42,664 AVF and 12,335 AVG that met inclusion criteria. A larger proportion of AVFs required interventions: 18,408 AVF (43.2%) versus 2594 AVG (21.0%; p < 0.01). Both AS-AVG and AS-AVF patients experienced patency loss at 1 year more frequently compared with unAS-AVG (67.5% & 57.5% vs 55.2% respectively). Patency loss was lowest in unAS-AVF (38.9%). These trends were robust on adjusted analysis (unAS-AVG reference, AS-AVG sHR = 1.44, p < 0.01; AS-AVF sHR = 1.08, p < 0.01, unAS-AVF sHR = 0.67, p < 0.01). AS-AVGs were more likely to be abandoned than unAS-AVGs (11.7% unAS-AVG vs 17.2% AS-AVG). Fistulae, assisted or not, had lower unadjusted rates of 1-year abandonment than grafts (8.9% AS-AVF vs 7.3% unAS-AVF). On adjusted analysis, AVF usage was protective against abandonment (unAS-AVG, reference; AS-AVF sHR = 0.67, p < 0.01; unAS-AVF sHR = 0.59, p < 0.01) while AS-AVG was not (AS-AVG sHR = 1.32, p < 0.01).

CONCLUSIONS

unAS-AVF have the best long-term outcomes. AS-AVF lose primary patency at a higher rate than unAS-AVG. AVGs may be a better choice than AVFs if veins are marginal and likely to require assisted maturation. Further research is needed to identify anatomic and physiologic factors that affect long-term performance and influence conduit choice.

Arteriovenous Access for Hemodialysis: A Review

Importance

Hemodialysis requires reliable vascular access to the patient's blood circulation, such as an arteriovenous access in the form of an autogenous arteriovenous fistula or nonautogenous arteriovenous graft. This Review addresses key issues associated with the construction and maintenance of hemodialysis arteriovenous access.

Observations

All patients with kidney failure should have an individualized strategy (known as Patient Life-Plan, Access Needs, or PLAN) for kidney replacement therapy and dialysis access, including contingency plans for access failure. Patients should be referred for hemodialysis access when their estimated glomerular filtration rate progressively decreases to 15 to 20 mL/min, or when their peritoneal dialysis, kidney transplant, or current vascular access is failing. Patients with chronic kidney disease should limit or avoid vascular procedures that may complicate future arteriovenous access, such as antecubital venipuncture or peripheral insertion of central catheters. Autogenous arteriovenous fistulas require 3 to 6 months to mature, whereas standard arteriovenous grafts can be used 2 to 4 weeks after being established, and "early-cannulation" grafts can be used within 24 to 72 hours of creation. The prime pathologic lesion of flow-related complications of arteriovenous access is intimal hyperplasia within the arteriovenous access that can lead to stenosis, maturation failure (33%-62% at 6 months), or poor patency (60%-63% at 2 years) and suboptimal dialysis. Nonflow complications such as access-related hand ischemia ("steal syndrome"; 1%-8% of patients) and arteriovenous access infection require timely identification and treatment. An arteriovenous access at high risk of hemorrhaging is a surgical emergency.

Conclusions and Relevance

The selection, creation, and maintenance of arteriovenous access for hemodialysis vascular access is critical for patients with kidney failure. Generalist clinicians play an important role in protecting current and future arteriovenous access; identifying arteriovenous access complications such as infection, steal syndrome, and high-output cardiac failure; and making timely referrals to facilitate arteriovenous access creation and treatment of arteriovenous access complications.

Early Ultrasound Surveillance of Newly-Created Hemodialysis Arteriovenous Fistula

Introduction

We assess if ultrasound surveillance of newly-created arteriovenous fistulas (AVFs) can predict nonmaturation sufficiently reliably to justify randomized controlled trial (RCT) evaluation of ultrasound-directed salvage intervention.

Methods

Consenting adults underwent blinded fortnightly ultrasound scanning of their AVF after creation, with scan characteristics that predicted AVF nonmaturation identified by logistic regression modeling.

Results

Of 333 AVFs created, 65.8% matured by 10 weeks. Serial scanning revealed that maturation occurred rapidly, whereas consistently lower fistula flow rates and venous diameters were observed in those that did not mature. Wrist and elbow AVF nonmaturation could be optimally modeled from week 4 ultrasound parameters alone, but with only moderate positive predictive values (PPVs) (wrist, 60.6% [95% confidence interval, CI: 43.9-77.3]; elbow, 66.7% [48.9-84.4]). Moreover, 40 (70.2%) of the 57 AVFs that thrombosed by week 10 had already failed by the week 4 scan, thus limiting the potential of salvage procedures initiated by that scan's findings to alter overall maturation rates. Modeling of the early ultrasound characteristics could also predict primary patency failure at 6 months; however, that model performed poorly at predicting assisted primary failure (those AVFs that failed despite a salvage attempt), partly because patency of at-risk AVFs was maintained by successful salvage performed without recourse to the early scan data.

Conclusion

Early ultrasound surveillance may predict fistula maturation, but is likely, at best, to result in only very modest improvements in fistula patency. Power calculations suggest that an impractically large number of participants (>1700) would be required for formal RCT evaluation.

Effect of preoperative arterial diameter on hospitalization and mortality in patients undergoing hemodialysis with forearm arteriovenous fistula access

BACKGROUND

As pointed out by the recent Kidney Disease Outcomes Quality Initiative Clinical Practice Guideline for Vascular Access, the current quality of evidence supporting preoperative vascular anatomy and patient outcomes is suboptimal and insufficient to make recommendations. This study assessed arteriovenous fistulas (AVFs) created with different preoperative arterial diameters on hospitalization and mortality rates in patients undergoing hemodialysis at the authors' center.

METHODS

Data from 261 patients who underwent HD between 2017 and 2019 were retrospectively examined. Differences in mortality and hospitalization rates between patients with different preoperative arterial diameters were compared, and risk factors for mortality and hospitalization were analyzed.

RESULTS

Smaller preoperative artery diameter (<2 mm) was associated with all-cause mortality (risk ratio [RR] 1.61 [95% confidence interval (CI) 1.45-1.90]; p < 0.01), and access-related (RR 1.68 [95% CI 1.24-2.44]; p < 0.01), and congestive heart failure (CHF)-related (RR 0.67 [95% CI 0.38-1.01]; p = 0.04) hospitalization. Longer catheter-dependent duration (⩾60 days) was associated with access-related hospitalization (RR 1.48 [95% CI 1.07-2.11]; p = 0.03), and higher postoperative brachial artery blood flow (⩾1500 mL/min) was associated with CHF-related hospitalization (RR 1.58 [95% CI 1.02-2.29]; p < 0.01). Higher postoperative brachial artery blood flow (⩾1500 mL/min) was associated with all-cause mortality (hazard ratio [HR] 1.20 [95% CI 1.09-2.32]; p = 0.04), whereas preoperative artery diameter (HR 0.98 [95% CI 0.93-1.86]; p = 0.08) and catheter-dependent duration (HR 1.06 [95% CI 0.47-2.13]; p = 0.82) were not associated with all-cause mortality.

CONCLUSION

In this cohort, smaller preoperative artery diameter was associated with all-cause and access-related hospitalizations, while a larger preoperative artery and higher postoperative brachial blood flow were associated with CHF-related hospitalization. However, only higher postoperative brachial blood flow was associated with all-cause mortality.

Clinical characteristics and preoperative ultrasound parameters related to low patency in radio-cephalic arteriovenous fistulas

INTRODUCTION

Our objective is to describe the clinical characteristics and preoperative ultrasound mapping parameters associated with primary and secondary patency of radio-cephalic arteriovenous fistulas (RCF).

METHODS

A retrospective, single-center, descriptive study, including patients undergoing a RCF creation between 2015 and 2019. Socio-demographic data and ultrasound parameters were collected and an analysis of primary and secondary patency was performed.

RESULTS

Eighty-four patients were included in this study. Mean age was 65.6 (±13.9) years; 76.6% were male. Mean preoperative ultrasound parameters: forearm cephalic vein diameter was 2.8 (±0.57) mm, radial artery diameter was 2.6 (±0.42) mm, radial artery systolic peak velocity was 68 (±14.3) cm/s radial artery resistance index was 0.76 (±0.9). At the end of the 4 years the follow-up, the mean primary and secondary patency were 47.2% and 80% respectively. Only female sex was significantly associated with a decrease in both primary patency (p = 0.043, HR = 0.48) and secondary patency (p = 0.021, HR = 0.023). Furthermore, radial artery systolic peak velocity (p = 0.007, HR = 2.6) showed a significant association with decreased primary patency and forearm cephalic vein diameter showed a borderline significant association with decreased secondary patency (p = 0.046, HR = 8.2).

CONCLUSIONS

A standardized evaluation by a vascular surgeon or nephrologist represent a key in the preoperative assessment of AVF candidates. Based on our results, we will consider to avoid distal vascular access in both female patients with lower radial artery systolic peak velocity (less than 68 cm/s) and borderline forearm cephalic vein diameter (less than 2.8 mm) after initial assessment in our clinical practice. Our results could encourage new studies in order to stablish the potential role of these parameters in the RCFs patency rates.

The feasibility and efficiency for constructing arteriovenous fistula with <2 mm vein-a systematic review and meta-analysis

Background

Autogenous arteriovenous fistula (AVF) is an efficient hemodialysis access for patients with end-stage kidney disease (ESKD). The specific threshold of vein diameter still not reached a consensus.

Method

We conducted a comprehensive search in PubMed, Embase, and Web of Science databases for articles which comparing the treatment outcomes of AVF with 2 mm as vein diameter threshold. Fixed and random effect model were used for synthesis of results. Subgroup analysis was designed to assess the risk of bias.

Result

Eight high-quality articles were included finally. Among a total of 1,075 patients (675 males and 400 females), 227 and 809 patients possessed <2 mm and ≥2 mm vein respectively. Apart from gender and coronary artery disease (P < 0.05), there was no significant difference in age, diabetes, hypertension or radial artery between maturation and non-maturation groups. The functional maturation rate was lower in patients with <2 mm vein according to fixed effect model [OR = 0.19, 95% CI (0.12, 0.30), P < 0.01]. There was no significant difference in primary [OR = 0.63, 95% CI (0.12, 3.25), P = 0.58] or cumulative patency rates [OR = 0.40, 95% CI (0.13, 1.19), P = 0.10].

Conclusion

Vein diameter less than 2 mm has a negative impact on the functional maturation rate of AVF, while it does not affect the primary and cumulative patency rates (12 months).

Sex Disparities in Arteriovenous Fistula Maturation Outcomes

BACKGROUND

The end-stage kidney disease life-plan aims to individualize hemodialysis (HD) access selection in patients requiring renal replacement therapy. Paucity of data on risk factors for poor arteriovenous fistula (AVF) outcomes limits the ability of physicians to guide their patients on this decision. This is especially true for female patients, who are known to have worse AVF outcomes when compared to male patients. The goal of this study was to identify risk factors associated with poor AVF maturation outcomes in female patients that will help guide individualized access selection.

METHODS

A retrospective review of 1,077 patients that had AVF creation between 2014 and 2021 at an academic medical center was performed. Maturation outcomes were compared between 596 male and 481 female patients. Separate multivariate logistic regression models were created for the male and female cohorts to identify factors associated with unassisted maturation. AVF was considered mature if it was successfully used for HD for 4-week sessions without need for further interventions. Unassisted fistula was defined as an AVF that matured without any interventions.

RESULTS

The male patients were more likely to receive more distal HD access; 378 (63%) male versus 244 (51%) female patients had radiocephalic AVF, P < 0.001. Maturation outcomes were significantly worse in female patients; 387 (80%) AVFs matured in females and 519 (87%) in male patients, P < 0.001. Similarly, the rate of unassisted maturation was 26% (125) in female patients versus 39% (233) in male patients, P < 0.001. Mean preoperative vein diameters were similar in both groups; 2.8 ± 1.1 mm in male versus 2.7 ± 0.97 mm in female patients, P = 0.17. Multivariate logistic regression analysis of the female patients revealed that Black race (odds ratio [OR]: 0.6, 95% confidence interval [CI]: 0.4-0.9, P = 0.045), radiocephalic AVF (OR: 0.6, 95% CI: 0.4-0.9, P = 0.045), and preoperative vein diameter <2.5 mm (OR: 1.4, 95% CI: 10.33-0.901.1-1.7, P = 0.014) were independent predictors of poor unassisted maturation in this cohort. In male patients, preoperative vein diameter <2.5 mm (OR: 1.4, 95% CI: 1.2-1.7, P < 0.001) and need for HD prior to AVF creation (OR: 0.6, 95% CI: 0.3-0.9, P = 0.018) were independent predictors of poor unassisted maturation.

CONCLUSIONS

Black women with marginal forearm veins may have worse maturation outcomes, and upper arm HD access should be considered when advising patients on their end-stage kidney disease life-plan.

Management of Immature Arteriovenous Fistulas

In patients requiring long-term hemodialysis for chronic kidney disease, an arteriovenous fistula is the preferred mode of hemodialysis access over synthetic arteriovenous graft or hemodialysis catheters. The National Kidney Foundation recommended in their Kidney Dialysis Outcomes Quality Initiative (KDOQI) Clinical Practice Guidelines that the creation of an autogenous arteriovenous fistula should initially be sought whenever possible. In 2003, a program named the Fistula First Breakthrough Initiative was initiated in the U.S. to increase the use of arteriovenous fistula for hemodialysis and to ultimately surpass the goal of 50% fistula use in incident and 40% fistula use in prevalent hemodialysis patients per recommendation by KDOQI Guidelines. While this goal was achieved, the encouraged creation of arteriovenous fistulas saw a rise in fistulas that failed to mature. Researchers have focused on developing strategies to optimize fistula maturation. Studies have revealed that the presence of stenoses and accessory draining veins may contribute to unsuccessful fistula maturation. Endovascular treatment, including balloon angioplasty and accessory vein embolization, aim to correct anatomical factors that negatively affect the maturation process. This article reviews the techniques and outcomes of endovascular treatment in the management of immature fistulas.

The use of AVF.SIM system for the surgical planning of arteriovenous fistulae in routine clinical practice

BACKGROUND

The number of patients treated with hemodialysis (HD) in Europe is more than half a million and this number increases annually. The arteriovenous fistula (AVF) is the vascular access (VA) of first choice, but the clinical outcome is still poor. A consistent number of AVFs fails to reach the desired blood flow rate for HD treatment, while some have too high flow and risk for cardiac complications. Despite the skill of the surgeons and the possibility to use Ultrasound investigation for mapping arm vasculature, it is still not possible to predict the blood flow volume that will be obtained after AVF maturation.

METHODS

We evaluated the potential of using a computational model (AVF.SIM) to predict the blood flow volume that will be achieved after AVF maturation, within a multicenter international clinical investigation aimed at assessing AVF.SIM predictive power. The study population included 231 patients, with data on AVF maturation in 124 patients, and on long-term primary patency in 180 patients.

RESULTS

At 1 year of follow-up, about 60% of AVFs were still patent, with comparable primary patency in proximal and distal anastomosis. The correlation between predicted and measured blood flow volume in the brachial artery at 40 days after surgery was statistically significant, with an overall correlation coefficient of 0.58 (p < 0.001). The percent difference between measured and predicted brachial blood flow 40 days after surgery was less than 30% in 72% of patients investigated.

CONCLUSIONS

The results indicate that the use of the AVF.SIM system allowed to predict with a good accuracy the blood flow volume achievable after VA maturation, for a given location and type of anastomosis. This information may help in AVF surgical planning, reducing the AVFs with too low or too high blood flow, thus improving AVF patency rate and clinical outcome of renal replacement therapy.

Vascular access interventional therapy of early arteriovenous fistula occlusion leading to long-term patency: A case report

Arteriovenous fistulas (AVFs) are frequently used for hemodialysis access, but approximately 15%-20% of AVFs fail to mature within 3 months of their creation. Vascular access interventional therapy (VAIVT) is typically performed for treating an immature AVF. However, it should be performed 4-6 weeks or later after AVF creation. Here, we present a case in which VAIVT effectively addressed AVF occlusion that occurred only 9 days after its creation. The patient was an 82-year-old woman with chronic kidney disease who underwent surgery to create a left radiocephalic AVF for hemodialysis. Nine days postoperatively, disappearance of the AVF sound prompted an angiography, revealing thrombosis near the AVF anastomosis. VAIVT successfully restored blood flow, resulting in AVF maturation, and with no thrombosis or flow dysfunction at 21 months after VAIVT. To the best of our knowledge, this case presents the earliest successful intervention for an occluded AVF.

Options for Dialysis and Vascular Access Creation

End-stage kidney disease (ESKD) affects nearly 800,000 patients in the United States. The choice of peritoneal dialysis (PD) versus hemodialysis (HD) should be patient centric. An ESKD Life-Plan is crucial with the goal of creating the right access, for the right patient, at the right time, for the right reason. Complex access should be considered when straightforward access options have been exhausted. Evolving techniques such as percutaneous access for HD and PD should be further investigated. Shared decision-making and palliative care is an essential part of the care of patients with CKD and ESKD..

Predictors of arteriovenous fistula maturation in hemodialysis patients: a prospective cohort from an ambulatory surgical center in Joinville, Brazil

INTRODUCTION

The high rate of arteriovenous fistula maturation failure is a concern in a scenario of growing numbers of patients on hemodialysis. Non-vascular factors tied to maturation success have not been fully discussed.

METHODS

This prospective observational cohort study included patients with CKD on dialysis or pre-dialysis prescribed arteriovenous fistula creation for the first time in an ambulatory surgical center in Joinville, Brazil, from January 2021 to July 2021. Anthropometric aspects, sociodemographic characteristics, comorbidities, and vascular parameters observed in Doppler ultrasound were analyzed. Variables associated with maturation were analyzed in multivariate models by logistic regression.

RESULTS

Eighty-eight of 145 participants (60.1%) were males. Included patients had a median age of 59 years. Successful arteriovenous fistula maturation occurred in 113 (77.9%) patients. Factors such as increased BMI, hematocrit, arm circumference, and skinfold thickness were associated with lower chances of arteriovenous fistula maturation in univariate analysis. On the other hand, larger vein and artery diameter and fistulas in the more proximal portion of the arm were associated with higher maturation success. In multivariate analysis, smoking and larger skinfold and arm circumference were associated with lower chances of successful maturation. Increased systolic blood pressure and vein diameter were associated with greater chance of success.

CONCLUSION

In addition to the vascular parameters assessed in Doppler ultrasonography, factors related to obesity and/or nutritional aspects may influence arteriovenous fistula maturation.

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

BACKGROUND

Arteriovenous fistulae mature less frequently in women than in men, leading to inferior patency and decreased fistula utilization in women. We hypothesized that both anatomic and physiologic sex differences explain reduced maturation.

METHODS

The electronic medical records of patients who had a primary arteriovenous fistula created from 2016 to 2021 at a single center were reviewed; sample size was determined using a power calculation. Postoperative ultrasound and laboratory tests were obtained at least 4 weeks after fistula creation. Primary unassisted fistula maturation was determined up to 4 years postprocedure.

RESULTS

A total of 28 women and 28 men with a brachial-cephalic fistula were analyzed. The inflow brachial artery diameter was smaller in women than in men, both preoperatively (4.2 ± 0.9 vs. 4.9 ± 1.0 mm, P = 0.008) and postoperatively (4.8 ± 0.8 vs. 5.3 ± 0.9 mm, P = 0.039). Despite similar preoperative brachial artery peak systolic velocity, women had significantly lower postoperative arterial velocity (P = 0.027). Fistula flow was reduced in women, particularly in the midhumerus (747.0 ± 570.4 vs. 1,117.1 ± 471.3 cc/min, P = 0.003). Percentages of neutrophils and lymphocytes were similar among women and men 6 weeks after fistula creation. However, women had reduced monocytes (8.5 ± 2.0 vs. 10.0 ± 2.6%, P = 0.0168). Among 28 men, 24 of 28 (85.7%) achieved unassisted maturation, whereas only 15 of 28 (53.6%) women had fistulae that matured without intervention. Secondary analysis using logistic regression suggested that postoperative arterial diameter was associated with maturation in men, while postoperative monocyte percentage was associated with maturation in women.

CONCLUSIONS

Sex differences during arteriovenous fistula maturation are present in arterial diameter and velocity, suggesting that both anatomic and physiologic differences in arterial inflow contribute to sex differences in fistula maturation. In men, postoperative arterial diameter is correlated with maturation, whereas in women, the significantly lower proportion of circulating monocytes suggests a role for the immune response in fistula maturation.

Effects of arteriovenous fistulas and central venous catheters on the cardiac function and prognosis of patients on maintenance hemodialysis

Objective

To investigate the effects of arteriovenous fistulas (AVFs) and central venous catheters (CVCs) on the left ventricular function (LVF) and prognosis of maintenance hemodialysis (MHD) patients.

Methods

This retrospective cohort study included 270 patients (139 with AVF and 131 with CVC) undergoing dialysis with newly established vascular access in the blood purification center of Nanhua hospital, University of South China, from January 2019 to April 2021. Dialysis efficiencies, LVF indexes, and one-year prognoses were compared.

Results

At six and twelve months after the establishment of vascular access, the mean urea clearances (Kt/V) and urea reduction ratio (URR) between the AVF- and the CVC-group were similar (P>0.05). The mean LVF values between the two groups were also similar before the establishment of vascular access (P>0.05), but the mean values of left ventricular end diastolic diameter (LVEDd), interventricular septal thickness (IVSTd), and left ventricular posterior wall thickness (LVPWT) in the AVF-group were higher than those in the CVC-group one year later, and mean early (E) and late (A) diastolic mitral velocities, E/A, and ejection fraction (EF) were lower than those in the CVC-group (P<0.05). The incidence of left ventricular hypertrophy and systolic dysfunction in the AVF-group was higher than that in the CVC-group (P<0.05). The hospitalization rate of AVF-group (23.02%) was lower than that of the CVC-group (49.61%) (P<0.05).

Conclusion

Both AVF and CVC can achieve appropriate dialysis effects in MHD patients. AVF has a negative impact on cardiac function while CVC has a high hospitalization rate.

Imaging Patients with Kidney Failure

The approach to imaging a patient with kidney failure continues to evolve. Overstatement of the risk of iodinated contrast material-induced (ie, contrast-induced) acute kidney injury and new guidelines for administration of gadolinium-based contrast media affect screening and the choice of contrast material. Treatment of kidney failure requires dialysis or a kidney transplant. Pretransplant imaging includes assessment for the feasibility of performing a transplant and evaluation for underlying malignancy and peripheral vascular disease. Patients with kidney failure are at high risk for renal cell carcinoma. Subtypes that occur exclusively or more commonly in patients with kidney failure, such as acquired cystic kidney disease, renal cell carcinoma, and clear cell papillary renal cell carcinoma, have specific clinical-pathologic characteristics, with indolent behavior. Performing US for dialysis planning increases the success of placement of an arteriovenous fistula, while postoperative US evaluation is essential in assessment of access dysfunction. Systemic manifestations in patients with kidney failure are multifactorial and may relate to the underlying cause of renal failure or may be secondary to treatment effects. Disturbances in mineral and bone metabolism and soft-tissue and vascular calcifications are seen in patients with chronic kidney disease and mineral bone disorder. Neurologic and cardiothoracic complications are also common. The authors provide a comprehensive overview of imaging considerations for patients with kidney failure, including the appropriate use of CT, MRI, and US with their respective contrast agents; the use of imaging in transplant workup and dialysis assessment; and the common renal and extrarenal manifestations of kidney failure. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

The challenging surgical vascular access creation

With the increasing life expectancy of patients with end-stage kidney disease, the creation and maintenance of hemodialysis vascular access are becoming more challenging. A comprehensive patient evaluation including a complete history, physical examination, and ultrasonographic vessel assessment is the foundation of the clinical evaluation. A patient-centered approach acknowledges the myriad of factors that impact the selection of optimal access for the distinct clinical and social circumstance of each patient. An interdisciplinary team approach involving various healthcare providers in all stages of hemodialysis access creation is important and associated with better outcomes. While patency is considered the most important parameter in most vascular reconstructive scenarios, the ultimate determinant of success in vascular access for hemodialysis is a circuit that allows consistent and uninterrupted delivery of the prescribed hemodialysis. The best conduit is one that is superficial, easily identified, straight, and of a large caliber. Individual patient factors and skill level of the cannulating technician also play a crucial role in the initial success and maintenance of vascular access. Special attention should be considered in dealing with more challenging groups such as the elderly population where the newest vascular access guidance from The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative will be transformative. The current guidelines recommend monitoring the vascular access by regular physical and clinical assessments, however, inadequate evidence is available to support routine ultrasonographic surveillance for improving access patency.

Association of Shear Stress with Subsequent Lumen Remodeling in Hemodialysis Arteriovenous Fistulas

BACKGROUND

Blood flow-induced wall shear stress is a strong local regulator of vascular remodeling, but its effects on arteriovenous fistula (AVF) remodeling are unclear.

METHODS

In this prospective cohort study, we used computational fluid dynamics simulations and statistical mixed-effects modeling to investigate the associations between wall shear stress and AVF remodeling in 120 participants undergoing AVF creation surgery. Postoperative magnetic resonance imaging data at 1 day, 6 weeks, and 6 months were used to derive current wall shear stress by computational fluid dynamic simulations and to quantify subsequent changes in AVF lumen cross-sectional area at 1-mm intervals along the proximal artery and AVF vein.

RESULTS

Combining artery and vein data, prior mean wall shear stress was significantly associated with lumen area expansion. Mean wall shear stress at day 1 was significantly associated with change in lumen area from day 1 to week 6 (11% larger area per interquartile range [IQR] higher mean wall shear stress, 95% confidence interval [95% CI], 5% to 18%; n =101), and mean wall shear stress at 6 weeks was significantly associated with change in lumen area from 6 weeks to month 6 (14% larger area per IQR higher, 95% CI, 3% to 28%; n =52). The association of mean wall shear stress at day 1 with lumen area expansion from day 1 to week 6 differed significantly by diabetes ( P =0.009): 27% (95% CI, 17% to 37%) larger area per IQR higher mean wall shear stress without diabetes and 9% (95% CI, -1% to 19%) with diabetes. Oscillatory shear index at day 1 was significantly associated with change in lumen area from day 1 to week 6 (5% smaller area per IQR higher oscillatory shear index, 95% CI, 3% to 7%), and oscillatory shear index at 6 weeks was significantly associated with change in lumen from 6 weeks to month 6 (7% smaller area per IQR higher oscillatory shear index, 95% CI, 2% to 11%). Wall shear stress spatial gradient was not significantly associated with subsequent remodeling. In a joint model, wall shear stress and oscillatory shear index statistically significantly interacted in their associations with lumen area expansion in a complex nonlinear fashion.

CONCLUSIONS

Higher wall shear stress and lower oscillatory shear index were associated with greater lumen expansion after AVF creation surgery.

Preditores da maturação de fístula arteriovenosa de pacientes em hemodiálise: coorte prospectiva de um centro cirúrgico ambulatorial, Joinville, Brasil

Resumo Introdução: A alta taxa de falha na maturação da fístula arteriovenosa é motivo de preocupação para o crescente número de pacientes em hemodiálise. Os fatores não vasculares não foram totalmente estudados em relação ao sucesso da maturação. Métodos: Estudo de coorte prospectivo, observacional de pacientes com DRC diálise ou pré-diálise encaminhados para a primeira criação de fístula arteriovenosa em um centro cirúrgico ambulatorial de Joinville, Brasil, de janeiro de 2021 a julho de 2021. Aspectos antropométricos, características sociodemográficas, comorbidades, além de fatores vasculares verificados pelo ultrassom Doppler. As variáveis associadas à maturação foram analisadas em modelos multivariados por regressão logística. Resultados: Dos 145 pacientes participantes, 88 (60,1%) eram homens, com idade mediana de 59 anos. Houve sucesso na maturação da fístula arteriovenosa em 113 (77,9%) pacientes. Fatores como aumento do IMC, hematócrito, circunferência do braço e valor das dobras cutâneas foram associados a menor chance de maturação da fístula arteriovenosa na análise univariada. Por outro lado, o maior diâmetro da veia e da artéria e fístulas na porção mais proximal do membro superior foram associados a maior sucesso de maturação. Na análise multivariada, tabagismo, maior dobra cutânea e circunferência do braço foram associados a menor chance de sucesso da maturação. O aumento da pressão arterial sistólica e o do diâmetro da veia foram associados a maior chance de sucesso. Conclusão: Além dos aspectos vasculares avaliados pela ultrassonografia Doppler, fatores relacionados à obesidade e/ou a aspectos nutricionais podem influenciar a maturação da fístula arteriovenosa.

Differential hemodynamics between arteriovenous fistulas with or without intervention before successful use

A significant number of arteriovenous fistulas (AVFs) fail to maturate for dialysis. Although interventions promote maturation, functional primary patency loss is higher for AVFs with interventions (assisted maturation) than AVFs without interventions (un-assisted maturation). Although blood flow-associated hemodynamics have long been proposed to affect AVF remodeling, the optimal hemodynamic parameters for un-assisted maturation are unclear. Additionally, AVF maturation progress is generally not investigated until 6 weeks after AVF creation, and the examination is focused on the AVF's venous limb. In this exploratory study, patients (n = 6) underwent magnetic resonance imaging (MRI) at 1 day, 6 weeks, and 6 months after AVF creation surgery. Before successful use for hemodialysis, three AVFs required intervention and three did not. MRI of the AVFs were used to calculate lumen cross-sectional area (CSA) and perform computational fluid dynamics (CFD) to analyze hemodynamics, including velocity, wall shear stress (WSS), and vorticity. For the venous limb, the no-intervention group and intervention group had similar pre-surgery vein diameter and 1-day post-surgery venous CSA. However, the no-intervention group had statistically larger 1-day venous velocity (0.97 ± 0.67 m/s; mean ± SD), WSS (333 ± 336 dyne/cm2) and vorticity (1709 ± 1290 1/s) than the intervention group (velocity = 0.23 ± 0.10 m/s; WSS = 49 ± 40 dyne/cm2; vorticity = 493.1 ± 227 1/s) (P < 0.05). At 6 months, the no-intervention group had statistically larger venous CSA (43.5 ± 27.4 mm2) than the intervention group (15.1 ± 6.2 mm2) (P < 0.05). Regarding the arterial limb, no-intervention AVF arteries also had statistically larger 1-day velocity (1.17 ± 1.0 m/s), WSS (340 ± 423 dyne/cm2), vorticity (1787 ± 1694 1/s), and 6-month CSA (22.6 ± 22.7 mm2) than the intervention group (velocity = 0.64 ± 0.36 m/s; WSS = 104 ± 116 dyne/cm2, P < 0.05; vorticity = 867 ± 4551/s; CSA = 10.7 ± 6.0 mm2, P < 0.05). Larger venous velocity, WSS, and vorticity immediately after AVF creation surgery may be important for later lumen enlargement and AVF maturation, with the potential to be used as a tool to help diagnose poor AVF maturation earlier. However, future studies using a larger cohort are needed to validate this finding and determine cut off values, if any.

Oxidative stress: An essential factor in the process of arteriovenous fistula failure

For more than half a century, arteriovenous fistula (AVFs) has been recognized as a lifeline for patients requiring hemodialysis (HD). With its higher long-term patency rate and lower probability of complications, AVF is strongly recommended by guidelines in different areas as the first choice for vascular access for HD patients, and its proportion of application is gradually increasing. Despite technological improvements and advances in the standards of postoperative care, many deficiencies are still encountered in the use of AVF related to its high incidence of failure due to unsuccessful maturation to adequately support HD and the development of neointimal hyperplasia (NIH), which narrows the AVF lumen. AVF failure is linked to the activation and migration of vascular cells and the remodeling of the extracellular matrix, where complex interactions between cytokines, adhesion molecules, and inflammatory mediators lead to poor adaptive remodeling. Oxidative stress also plays a vital role in AVF failure, and a growing amount of data suggest a link between AVF failure and oxidative stress. In this review, we summarize the present understanding of the pathophysiology of AVF failure. Furthermore, we focus on the relation between oxidative stress and AVF dysfunction. Finally, we discuss potential therapies for addressing AVF failure based on targeting oxidative stress.

Pre-existing Systolic Dysfunction is the Most Powerful Predictor of Failed Arteriovenous Fistula Maturation

BACKGROUND

Patients requiring hemodialysis access creation often have significant comorbid conditions, which may impact access maturation. Underlying cardiac dysfunction likely plays an important role in the maturation of arteriovenous fistulae (AVF). The effect of specific parameters of cardiac function on successful AVF creation has not previously been explored.

METHODS

A retrospective chart analysis of patients undergoing first-time AVF creation at a single center from 2011 to 2018 was performed. Patients with a transthoracic echocardiogram within the 12 months prior to surgery were included. Standard demographic and perioperative variables were collected, in addition to echocardiographic and vascular mapping data. The primary outcome was access maturation, defined as the use of the access site for hemodialysis at 3, 6, and 12 months after surgery.

RESULTS

A total of 121 patients met inclusion criteria with a cumulative AVF maturation rate of 57% (69/121) in this select population. Patients with pre-existing systolic cardiac dysfunction were more than 5 times less likely to see their AVF mature by one year postsurgery (OR = 0.17, P = 0.018). Preoperative venous diameter, access site location, and the type of fistula did not differ significantly between patients with and without systolic dysfunction. Selection of the cephalic vein as the venous anastomosis and diastolic dysfunction (≥ Grade 2) were also associated with lower rates of access maturation, although these associations were less robust.

CONCLUSIONS

Systolic cardiac dysfunction is the most important nonmodifiable variable associated with failed AVF maturation. Patients requiring hemodialysis with significant pre-existing cardiac dysfunction may not be appropriate for permanent access creation, and long-term catheter use should be seriously considered as an alternative.

The association between the locations of arteriovenous fistulas and patency rates: A systematic review and meta-analysis

BACKGROUND

The arteriovenous fistulas (AVF) continue to be the most prevalent type of vascular access for hemodialysis (HD). However, the appropriate locations of AVF are controversial. We conducted the meta-analysis to investigate the differences in patency between upper-arm and forearm AVF.

METHODS

PubMed, EMBASE, CENTRAL, and ISI Web of Science were searched to identify studies with differences in AVF patency at different locations. Reviewers searched the database, screened studies according to inclusion criteria, and conducted Meta-analysis.

RESULTS

A total of 12 studies involving 3437 patients were selected. Pooled data showed that primary patency (PP) of AVF were higher in upper-arm than forearm at 1 and 2 years (odds ratio [OR] = 1.54, p = 0.0005; OR = 2.45, p = 0.001), but the differences in cumulative patency (CP) were not statistically significant at 1 and 2 years (OR = 2.10, p = 0.08; OR = 2.16, p = 0.1). The differences in PP and CP between upper-arm and forearm AVF in patients older than 65 years were not statistically significant at 1 (OR = 1.61, p = 0.05; OR = 2.05, p = 0.17) and 2 years (OR = 3.40, p = 0.13; OR = 1.38, p = 0.16). In Asian patients, the differences in PP and CP between upper-arm and forearm AVF were not statistically significant at 1 (OR = 1.17, p = 0.41; OR = 1.02, p = 0.94) and 2 years (OR = 2.95, p = 0.08; OR = 1.23, p = 0.41).

CONCLUSIONS

In this study, the CP of upper-arm and forearm AVF was similar in overall population. There was no difference in PP and CP of AVF between upper-arm and forearm in Asian population or the elderly. The forearm AVF could be consider to be the first choice. for Asian patients or the elderly.

Maturation and survival of arteriovenous fistula: The challenge starts from the preoperative assessment stage

BACKGROUND

It is necessary to assess the association between the preoperative indicators and the maturation and survival of arteriovenous fistula (AVF).

METHODS

We retrospectively identified 236 patients with a new AVF created between 2016 and 2018 in our Dialysis Center.

RESULTS

Multivariate Logistic regression showed that preoperative arterial diameter (odds ratio [OR] = 1.452, 95% confidence interval [CI] [1.233, 1.710], p < 0.001), preoperative venous diameter (OR = 1.296, 95% CI [1.166, 1.477], p < 0.001), left ventricular ejection fraction (LVEF) (OR = 1.187, 95% CI [1.103, 1.277], p < 0.001), and diabetes mellitus (OR = 0.245, 95% CI [0.107, 0.560], p = 0.01) were independent influential factors for AVF maturation. Two years after the AVF surgery follow-up, multivariate Cox proportional-hazards model showed that the preoperative arterial diameter (OR = 0.510, 95% CI [0.320, 0.813], p = 0.005), preoperative venous diameter (OR = 0.940, 95% CI [0.897, 0.985], p = 0.010) and diabetes mellitus (OR = 1.785, 95% CI [1.117, 2.855], p = 0.016) was prognostic factors of AVF survival. The Kaplan-Meier method showed that the primary survival of AVF in patients with different preoperative arterial diameter was statistically significant (log-rank χ²  = 15.415, p < 0.001), while the secondary survival was not statistically significant (log-rank χ²  = 0.131, p = 0.717).

CONCLUSION

In our cohort, the preoperative arterial and venous diameter and diabetes mellitus were independent influential factors for AVF maturation and prognostic factors of AVF survival. However, the preoperative LVEF only associated with the maturation of AVF. Meanwhile, smaller arterial diameter (≤2.15 mm) was associated with AVF maturation failure, but did not impact secondary survival of AVF.

Upper limb anatomy and preoperative mapping

Vascular access is absolutely essential for haemodialysis due to its relationship with quality of dialysis and associated morbidity. Therefore, it must be monitored and continuously surveilled from the moment it is created to prevent failure in maturation and thrombosis. Multidisciplinary collaboration is necessary when the main aim is to achieve the adequate vascular access flow with the fewest possible complications. The starting point, and probably the main one, is vascular access planning. This planning requires both a deep understanding of the anatomy of the upper limb and enough skill to examine it by Doppler ultrasound. The aim of this article is to review the anatomical and haemodynamical concepts of the arterial and venous vascular tree and explain how to perform ultrasound mapping, optimising the technical resources provided by this tool. Likewise, adequate access creation criteria that minimise the risk of failure and associated complications will be discussed.

Arteriovenous Fistula Nonmaturation: What's the Immune System Got to Do with It?

Background

Arteriovenous fistula (AVF) nonmaturation is a persistent problem, particularly among female and Black patients. Increasingly, the immune system has been recognized as an important contributor to vascular disease, but few studies have examined immune factors relative to AVF maturation outcomes. This study evaluated the association of serum panel reactive antibodies (PRA), a measure of immune system reactivity assessed in patients undergoing kidney transplant evaluation, with AVF nonmaturation.

Methods

We identified 132 patients at our institution who underwent surgical AVF placement between 2010-2019 and had PRA testing within 1 year of AVF creation. Multivariable logistic regression was used to determine the association of patient demographic and clinical factors, class I and class II PRA levels, and preoperative arterial and venous diameters with AVF maturation outcomes.

Results

AVF nonmaturation was more likely in females than males (44% versus 20%, P=0.003) and in Black than white patients (40% versus 13%, P=0.001). Class II PRA was higher in females than males (12%±23% versus 4%±13%, P=0.02). In the multivariable model, AVF nonmaturation was associated with class II PRA (adjusted odds ratio [aOR], 1.34 per 10% increase; 95% confidence interval [95% CI], 1.04 to 1.82, P=0.02) and Black race (aOR, 3.34; 95% CI, 1.02 to 10.89, P=0.03), but not with patient sex or preoperative arterial or venous diameters.

Conclusions

The association of elevated class II PRA with AVF nonmaturation suggests the immune system may play a role in AVF maturation outcomes, especially among female patients.

New Frontiers in Vascular Access Practice: From Standardized to Patient-tailored Care and Shared Decision Making

Vascular access planning is critical in the management of patients with advanced kidney disease who elect for hemodialysis for RRT. Policies put in place more than two decades ago attempted to standardize vascular access care around the model of optimal, namely arteriovenous fistula, and least preferred, namely central venous catheter, type of access. This homogenized approach to vascular access care emerged ineffective in the increasingly heterogeneous and complex dialysis population. The most recent vascular access guidelines acknowledge the limitations of standardized care and encourage tailoring vascular access care on the basis of patient and disease characteristics. In this article, we discuss available literature in support of patient-tailored access care on the basis of differences in vascular access outcomes by biologic and social factors-age, sex, and race. Further, we draw attention to the overlooked dimension of patient-reported preferences and shared decision making in the practice of vascular access planning. We discuss milestones to overcome as requisite steps to implement effective shared decision making in vascular access care. Finally, we take into consideration local practice cofactors as major players in vascular access fate. We conclude that a personalized approach to hemodialysis vascular access will require dynamic care specifically relevant to the individual on the basis of biologic factors, fluctuating clinical needs, values, and preferences.

Study on prediction of arterio-venous fistula maturation by flow mediated dilatation and AVF blood flow

BACKGROUND

The physiology and pathology of AVF maturation depends on the vessels characteristics and its ability to remodel. Outcome of AVF using flow mediated dilatation (FMD), AVF blood flow and diameter has been studied.

METHODOLOGY

Present observational study included single stage AVF (both Radiocephalic and Brachiocephalic) in consecutive CKD five patients (n = 158) prospectively over 1 year. Demographic and Doppler ultrasound parameters of upper limb (for vessel diameter and FMD) at baseline were recorded. Blood flow, diameter and depth of AVF were studied at 2, 6 and 12 weeks and their association with clinical maturation (usage of fistula with two needles for 75% of dialysis sessions during 15 day period) was studied (n = 129, after excluding lost to followup and expired patients; accordingly cohort was divided in matured (M) or non-matured (NM) groups. Clinical and radiological parameters between both groups were compared; receiver operator curve (ROC) and correlation of Doppler parameters were analysed.

RESULTS

Of 129 AVF, 67.4% were matured and 32.5% non-matured. Mean age was 40 years with male predominance75% in both the groups. The mean arterial diameter for distal (NM = 1.96 ± 0.58 and M = 2.02 ± 0.41) and proximal AVF (NM = 3.37 ± 0.82 and M = 3.36 ± 0.75) was not statistically different in both the groups. The matured fistula group had a mean FMD of 11.67 ± 4.09 as against FMD value of 9.365 ± 3.55 in the failed fistula group (p value 0.01). For maturation prediction, sensitivity and specificity of blood flow at 2 weeks were 86.2% and 59.5% and at 6 weeks 96.6% and 64.3%, respectively. In multivariate analysis predictors for AVF maturation were FMD (adjusted odds ratio (AOR) = 1.15) and blood flow (AOR = 1.67).

CONCLUSION

Second and Sixth week AVF blood flow was found to be predicting AVF maturation. Higher baseline FMD correlated with the AVF maturation, but not with vessel diameter.

Outcomes and predictors of failure of arteriovenous fistulae for hemodialysis

Purpose

Arteriovenous fistula(AVF) is preferred vascular access for hemodialysis but has primary failure in 20–60%. Studying predictors of AVF failure would help plan appropriate management.We studied AVF outcomes, clinical and vascular factors predicting their failure in patients requiring hemodialysis.

Methods

Retrospective study of patients with AVF creation from January 2017 to December 2018. Outcomes studied were immediate (< 72 h), primary (3 months) AVF failure, six-month/one-year patency, analyzed for predictive clinical, vascular factors as assessed using Pre-operative Doppler Ultrasound(DUS).

Results

Of 530 AVFs in 460 patients, DUS was done in 426/530 (80.4%), 349/460 (75.8%) were males, mean age was 53.10 ± 14.54 (18–91), 215/460(46.7%) had Diabetes mellitus(DM), 423/460(92%) hypertension. AVFs were radiocephalic in 79/530 (14.9%), brachiocephalic 418/530 (78.9%), brachiobasilic 33/530 (6.2%). AVF Immediate/Primary failure was seen in 64/530 (12.1%), 90/352 (25.6%); Patency at six months/one year in 253/352(71.8%),191/305 (62.6%), respectively. Older age had less immediate failures (AOR 0.97, CI 0.95–0.99, p 0.03). Feeding arterial diameter predicted immediate and primary failure on univariate analysis [OR 0.64 (95% CI 0.49–0.83), 0.62 (95% CI 0.47–0.89), respectively], but not multivariate. Artery diameter of > 4.0 mm had less failures [immediate (p 0.01), primary (p 0.02)], < 2.0 mm had specificity 95.9% and 95.4% for immediate, primary failure respectively.

Conclusion

AVF failure is 12.1%, immediately; 25.6% three months after construction, Patency at 6 months is 71.8%, one year 62.6%. Immediate failures decrease with age. Artery diameters > 4.0 mm had less, < 2.0 mm had more failures.