Arteriovenous Fistula Maturation Failure in a Large Cohort of Hemodialysis Patients in the Netherlands

The effect of virtual reality glasses on pain and patient satisfaction in arteriovenous fistula cannulation procedure

AIMS

To determine the effect of virtual reality glasses intervention on pain, vital signs, and patient satisfaction of hemodialysis patients undergoing AVF catheter puncture.

DESIGN

Randomized controlled study.

METHODS

The study was conducted in 60 patients receiving dialysis treatment in the HD unit of a public hospital in Turkey. The data were collected via the "Patient Identification Form", "Visual Analog Scale/VAS" and "Hemodynamics Variables Inspection Form". The patients in the experiment group watched videos through the virtual reality glasses for totally 5 minutes in average, 2 minutes before the AVF cannulation process and 3 minutes during the process. No intervention was applied to the patients in the control group other than the normal nursing interventions in the HD unit.

RESULTS

In the intra-group comparisons, the 2nd and 3rd measurement average pain level scores of the patients with in the experimental group were determined to be statistically significantly lower compared to their 1st measurement (p < 0.05); the 3rd measurement average pain level scores of the control group were determined to be statistically significantly lower compared to their 1st and 2nd measurements (p < 0.05).

CONCLUSIONS

It was determined that the virtual reality glasses decreased the pain that emerges during the AVF cannulation process and increased the patient satisfaction level. It is suggested that the virtual reality glasses should be used by the nurses in the HD unit since it is easily applicable in coping with pain in the patients and since it is an invasive method.

ARTERIOVENOUS FISTULA FOR HEMODIALYSIS IN RELATION TO THE TIMING OF CREATION: ANALYSIS OF KEY FACTORS

Timely creation of an arteriovenous fistula is not always feasible. The aim was to determine the key factors for functionality and maturation of arteriovenous fistulas in relation to timing of its creation. The research was conducted at the Department of Nephrology and Dialysis, Kragujevac University Clinical Center, Kragujevac, Serbia, in patients who had had a fistula surgically created over a period of fifteen years. A total of 1089 patients were registered. All clinical and biochemical parameters that were of interest for this study were analyzed. The group of patients with fistulas created before the start of hemodialysis was statistically different from the group of patients whose fistulas were created after the start of hemodialysis according to vein lumen (p=0.005), systolic blood pressure (p<0.001), total cholesterol (p<0.001), HDL cholesterol (p=0.008) and LDL cholesterol (p<0.001). Predictive parameters of the initial dysfunction were vein diameter (p=0.004), cholesterol (p=0.008) and LDL cholesterol (p=0.033), while the maturation parameter was systolic blood pressure (p=0.042). In conclusion, predictive parameters of initial fistula dysfunction are vein diameter, cholesterol and LDL cholesterol, while systolic blood pressure is most important for maturation.

Intraoperative transit time flow measurement predicts maturation of radiocephalic arteriovenous fistulas

OBJECTIVE

The arteriovenous fistula (AVF) is the first choice for gaining vascular access for hemodialysis. However, 20% to 50% of AVFs fail within 4 months after creation. Although demographic risk factors have been described, there is little evidence on the intraoperative predictors of AVF maturation failure. The aim of this study was to assess the predictive value of intraoperative transit time flow measurements (TTFMs) on AVF maturation failure.

METHODS

In this retrospective cohort study, intraoperative blood flow, measured using TTFM, was compared with AVF maturation after 6 weeks in 55 patients. Owing to its significantly higher prevalence and risk of nonmaturation, the radiocephalic AVF (RCAVF) was the main focus of this study. A recommended cutoff point for high vs low intraoperative blood flow was determined for RCAVFs, using a receiver operating characteristic curve.

RESULTS

The average intraoperative blood flow in RCAVFs was 156 mL/min. Patients with an intraoperative blood flow equal or lower than the determined cutoff point of 160 mL/min, showed a 3.03 times increased risk of AVF maturation failure after 6 weeks, compared with patients with a higher intraoperative blood flow (P < .001).

CONCLUSIONS

The intraoperative blood flow in RCAVFs measured by TTFM provides an adequate means of predicting AVF nonmaturation 6 weeks after surgery. For RCAVFs, a cutoff point for intraoperative blood flow of 160 mL/min is recommended for maximum sensitivity and specificity to predict AVF maturation failure after 6 weeks.

A systematic review of prediction models on arteriovenous fistula: Risk scores and machine learning approaches

OBJECTIVE

Failure-to-mature and early stenosis remains the Achille's heel of hemodialysis arteriovenous fistula (AVF) creation. The maturation and patency of an AVF can be influenced by a variety of demographic, comorbidity, and anatomical factors. This study aims to review the prediction models of AVF maturation and patency with various risk scores and machine learning models.

DATA SOURCES AND REVIEW METHODS

Literature search was performed on PubMed, Scopus, and Embase to identify eligible articles. The quality of the studies was assessed using the Prediction model Risk Of Bias ASsessment (PROBAST) Tool. The performance (discrimination and calibration) of the included studies were extracted.

RESULTS

Fourteen studies (seven studies used risk score approaches; seven studies used machine learning approaches) were included in the review. Among them, 12 studies were rated as high or unclear "risk of bias." Six studies were rated as high concern or unclear for "applicability." C-statistics (Model discrimination metric) was reported in five studies using risk score approach (0.70-0.886) and three utilized machine learning methods (0.80-0.85). Model calibration was reported in three studies. Failure-to-mature risk score developed by one of the studies has been externally validated in three different patient populations, however the model discrimination degraded significantly (C-statistics: 0.519-0.53).

CONCLUSION

The performance of existing predictive models for AVF maturation/patency is underreported. They showed satisfactory performance in their own study population. However, there was high risk of bias in methodology used to build some of the models. The reviewed models also lack external validation or had reduced performance in external cohort.

Elevated Leukocyte Glucose Index Is Associated with Long-Term Arteriovenous Fistula Failure in Dialysis Patients

(1) Background: Arteriovenous fistula (AVF) is the preferred type of vascular access for dialysis in patients with end-stage kidney disease (ESKD). However, the primary patency of AVF at one year is under 70% due to several risk factors and comorbidities. Leukocyte glucose index (LGI), a new biomarker based on blood leukocytes and glucose values, has been found to be associated with poor outcomes in cardiovascular disease. The aim of this study is to analyze the impact of LGI on the long-term primary patency of AVF following dialysis initiation. (2) Methods: We conducted a retrospective observational study in which we initially enrolled 158 patients with ESKD admitted to the Vascular Surgery Department of the Emergency County Hospital of Targu Mures, Romania, to surgically create an AVF for dialysis between January 2020 and July 2023. The primary endpoint was AVF failure, defined as the impossibility of performing a chronic dialysis session due to severe restenosis or AVF thrombosis. After follow-up, we categorized patients into two groups based on their AVF status: "functional AVF" for those with a permeable AVF and "AVF failure" for those with vascular access dysfunction. (3) Results: Patients with AVF failure had a higher prevalence of atrial fibrillation (p = 0.013) and diabetes (p = 0.028), as well as a higher LGI value (1.12 vs. 0.79, p < 0.001). At ROC analysis, LGI had the strongest association with the outcome, with an AUC of 0.729, and an optimal cut-off value of 0.95 (72.4% sensitivity and 68% specificity). In Kaplan-Meier survival analyses, patients in the highest tertile (T3) of LGI had a significantly higher incidence of AVF failure compared to those in tertile 1 (p = 0.019). Moreover, we found that patients with higher baseline LGI values had a significantly higher risk of AVF failure during follow-up (HR: 1.48, p = 0.003). The association is independent of age and sex (HR: 1.65, p = 0.001), cardiovascular risk factors (HR: 1.63, p = 0.012), and pre-operative vascular mapping determinations (HR: 3.49, p = 0.037). (4) Conclusions: In conclusion, high preoperative values of LGI are positively associated with long-term AVF failure. The prognostic role of the biomarker was independent of age, sex, cardiovascular risk factors, and pre-operative vascular mapping determinations.

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

Objectives

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

Methods

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

Results

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

Conclusion

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

The rodent models of arteriovenous fistula

Arteriovenous fistulas (AVFs) have long been used as dialysis access in patients with end-stage renal disease; however, their maturation and long-term patency still fall short of clinical needs. Rodent models are irreplaceable to facilitate the study of mechanisms and provide reliable insights into clinical problems. The ideal rodent AVF model recapitulates the major features and pathology of human disease as closely as possible, and pre-induction of the uremic milieu is an important addition to AVF failure studies. Herein, we review different surgical methods used so far to create AVF in rodents, including surgical suturing, needle puncture, and the cuff technique. We also summarize commonly used evaluations after AVF placement. The aim was to provide recent advances and ideas for better selection and induction of rodent AVF models. At the same time, further improvements in the models and a deeper understanding of AVF failure mechanisms are expected.

Comparative analysis of RADAR vs. conventional techniques for AVF maturation in patients with blood viscosity and vessel elasticity-related diseases through fluid-structure interaction modeling: Anemia, hypertension, and diabetes

PURPOSE

This study aims to compare two surgical techniques, the standard Vein-to-Artery and the newer Artery-to-Vein (Radial Artery Deviation And Reimplantation; RADAR), for enhancing the success of Arterio-Venous Fistula maturation in end-stage renal disease patients. The impact of diseases like anemia, diabetes, hypertension, and chronic kidney disease were considered. The goals are to advance Arterio-Venous Fistula (AVF) surgery, improve patient outcomes, and contribute to evidence-based surgical guidelines.

METHODS

Fluid-structure interaction modeling was employed to investigate how hemodynamic and mechanical stresses impact arteriovenous fistula maturation, with a particular focus on the role of wall shear stress in determining maturation outcomes. The critical threshold for vessel injury was identified as wall shear stress values exceeding 35 N/m2, while stenosis formation was projected to occur at levels below 1 N/m2. This work introduced a novel approach by considering disease-related factors, including blood viscosity (anemia), and vessel elasticity (diabetes, hypertension, and chronic kidney diseases), which directly influence hemodynamics and the generation of wall shear stress. Furthermore, the model was designed to incorporate varying thicknesses and elasticities for both the vein and artery, accurately representing authentic vascular anatomy.

RESULTS

The RADAR technique has demonstrated superior performance compared to the standard technique by providing appropriate wall shear stress in critical regions and minimizing the risk of wall damage. Its use of a thicker vessel also reduces the risk of vessel injury, making it particularly effective for patients with Chronic Kidney Disease (CKD), hypertension, anemia, and diabetes, ensuring optimal blood flow and fewer complications. However, there are minor concerns about stenosis formation in hypertension and anemia cases, which could be mitigated by adjusting the anastomosis angle to be lower than 30°.

CONCLUSION

Diabetes and hypertension have significant physiological effects that increase the risks associated with arteriovenous fistula maturation. The anemic condition resulting from CKD may help reduce vessel injury but raises concerns about potential stenosis formation. Despite these co-morbidities, the RADAR technique has demonstrated its ability to induce more favorable hemodynamic changes, promoting arteriovenous fistula maturation.

Effect of exercises on the maturation of newly created arteriovenous fistulas over distal and proximal upper limb: A systematic review and meta-analysis

The aims of our review were: (i) to evaluate the effect of post-operative upper extremity exercise on maturation of AVFs, stratified by their locations. (ii) To evaluate the effect of pre-operative arm exercise on patients' superficial vein caliber of patients. Literature search was performed on PubMed, Cochrane Library, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and China National Knowledge Infrastructure (CNKI) to identify eligible articles. The quality of the randomized controlled trials (RCTs) were assessed using the Cochrane Risk of Bias tool 2.0. In the Meta-analysis, Risk ratios (RRs) of clinical maturation and ultrasonographic maturation were pooled from studies focused on post-operative exercise program; Mean difference (MD) of venous caliver was pooled from those studied pre-operative exercise. Nine studies (six for post-operative exercise; three for pre-operative exercise) were included in the review. Among the AVFs created in distal region (158 patients in exercise group and 144 patients in control group), there was a significantly superior clinical maturation (RR: 1.28; 95% CI: 1.10-1.48, p = 0.001; I2 = 0), and ultrasonographic maturation (RR: 1.30; 95% CI: 1.07-1.59, p = 0.009; I2 = 0) in the exercise group in comparison to the control group. For the AVFs created in proximal region (93 and 96 patients in exercise group and control group respectively), there is no significant difference in clinical maturation (RR:1.25, 95% CI: 0.88-1.78, p = 0.27, I2 = 74%) and ultrasonographic maturation (RR: 1.17, 95% CI: 0.97-1.40, p = 0.11, I2 = 43%) between the exercise group and controls. For pre-operative exercise, the mean difference of 0.34 mm (95% CI: 0.23-0.46, p < 0.001, I2 = 87% ) was found for vein size. In conclusion, existing upper extremity exercise programs appear to be useful in facilitating maturation of AVFs created in distal region, while its effect on fistulas created in proximal region is less certain. However, more robust trials are warranted to establish these findings.

The clinical journey and healthcare resources required for dialysis access of end-stage kidney disease patients during their first year of hemodialysis

BACKGROUND

Creation and maintenance of dialysis vascular access (VA) is a major component of healthcare resource utilization and cost for patients newly started on hemodialysis (HD). Different VA format arises due to patient acceptance of anticipatory care versus late preparation, and clinical characteristics. This study reviews the clinical journey and resource utilization required for different VA formats in the first year of HD.

METHOD

Data of patients newly commenced on HD between July 2015 and June 2016 were reviewed. Patients were grouped by their VA format: (A) pre-emptive surgically created VA (SCVA), (B) tunneled central venous catheter (CVC) followed by SCVA creation, (C) long-term tunneled CVC only. Clinical events, number of investigations and procedures, hospital admissions, and incurred costs of the three groups were compared.

RESULTS

In the multivariable analysis, the cost incurred by the group A patients had no significant difference to that incurred in the group B patients (p = 0.08), while the cost of group C is significantly lower (p < 0.001). Both the 62.7% of group A with successful SCVA who avoided tunneled CVC usage, and those with a functionally matured SCVA in group B (66.1%), used fewer healthcare resources and incurred less cost for their access compared to those did not (p = 0.01, p = 0.02, respectively) during the first year of HD.

CONCLUSION

With comparable cost, a pre-emptive approach enables avoidance of tunneled CVC. Tunneled CVC only access format incurred lower cost and is suitable for carefully selected patients. Successful maturation of SCVA greatly affects patients' clinical journey and healthcare cost.

Hemodialysis Access: US for Preprocedural Mapping and Evaluation of Maturity and Access Dysfunction

Patients with kidney failure require kidney replacement therapy. While renal transplantation remains the treatment of choice for kidney failure, renal replacement therapy with hemodialysis may be required owing to the limited availability and length of time patients may wait for allografts or for patients ineligible for transplant owing to advanced age or comorbidities. The ideal hemodialysis access should provide complication-free dialysis by creating a direct connection between an artery and vein with adequate blood flow that can be reliably and easily accessed percutaneously several times a week. Surgical arteriovenous fistulas and grafts are commonly created for hemodialysis access, with newer techniques that involve the use of minimally invasive endovascular approaches. The emphasis on proactive planning for the placement, protection, and preservation of the next vascular access before the current one fails has increased the use of US for preoperative mapping and monitoring of complications for potential interventions. Preoperative US of the extremity vasculature helps assess anatomic suitability before vascular access creation, increasing the rates of successful maturation. A US mapping protocol ensures reliable measurements and clear communication of anatomic variants that may alter surgical planning. Postoperative imaging helps assess fistula maturation before cannulation for dialysis and evaluates for early and late complications associated with arteriovenous access. Clinical and US findings can suggest developing stenosis that may progress to thrombosis and loss of access function, which can be treated with percutaneous vascular interventions to preserve access patency. Vascular access steal, aneurysms and pseudoaneurysms, and fluid collections are other complications amenable to US evaluation. ©RSNA, 2023 Supplemental material is available for this article. Test Your Knowledge questions for this article are available through the Online Learning Center.

Sex disparities in hemodialysis access outcomes: A systematic review

The goal of this systematic review was to collate and summarize the current literature on hemodialysis access outcomes in females, identify differences between females and men, and provide a foundation for future research. A systematic review of the English-language literature was conducted by searching PubMed and Google Scholar for the following terms: "sex," "hemodialysis access," "arteriovenous fistula," "arteriovenous graft," and "dialysis catheter." Reference lists from the resulting articles were also evaluated to ensure that any and all relevant primary sources were identified. Studies were then screened by two independent reviewers for inclusion. Of 967 total studies, 53 ultimately met inclusion criteria. Females have lower maturation rates; have decreased rates of primary, primary-assisted, and secondary patency; require more procedures per capita to achieve maturation and to maintain fistula patency; are more likely to receive dialysis via an arteriovenous graft or central venous catheter; and require a longer time and potentially more assistive invasive interventions to achieve a mature fistula. Our findings emphasize the urgent need for further research to evaluate and address the causes of these disparities. Discussion with patients undergoing hemodialysis should include these findings to improve patient education, expectations, satisfaction, and outcomes.

Central venous catheter-related complications in older haemodialysis patients: A multicentre observational cohort study

BACKGROUND

Central venous catheters (CVC) remain a commonly used vascular access option in haemodialysis, despite guidelines advising to preferably use arteriovenous fistulae. Compared to younger patients, the risk-benefit ratio of CVC in older patients might be more beneficial, but previous studies mainly focussed on catheter-related bacteraemia and/or assessed tunnelled CVC (TCVC) only. This study's aim was to compare all catheter-related infections and malfunctions in older patients with younger patients using all CVC subtypes.

MATERIALS AND METHODS

We used data from DUCATHO, a multicentre observational cohort study in The Netherlands. All adult patients in whom a CVC was placed for haemodialysis between 2012 and 2016 were included. The primary endpoint was the occurrence of catheter-related infections, comparing patients aged ⩾70 years with patients aged <70 years (reference). As secondary endpoints, catheter malfunctions and catheter removal due to either infection or malfunction were assessed. Using Cox proportional hazards and recurrent events modelling, hazard ratios (HR) with 95% confidence intervals (CI) were calculated with adjustment of prespecified confounders. Additionally, endpoints were assessed for non-tunnelled CVC (NTCVC) and TCVC separately.

RESULTS

A total of 1595 patients with 2731 CVC (66.5% NTCVC, 33.1% TCVC) were included. Of these patients, 1001 (62.8%) were aged <70 years and 594 (37.2%) ⩾70 years. No statistically significant difference was found for the occurrence of catheter-related infections (adjusted HR 0.80-95% CI 0.62-1.02), catheter malfunction (adjusted HR 0.94-95% CI 0.75-1.17) and catheter removal due to infection or malfunction (adjusted HR 0.94-95% CI 0.80-1.11). Results were comparable when assessing NTCVC and TCVC separately.

CONCLUSION

Patients aged ⩾70 to <70 years have a comparable risk for the occurrence of catheter-related infections and catheter malfunction. These findings may help when discussing treatment options with older patients starting haemodialysis and may inform the current debate on the best vascular access for these patients.

VAVASC study: Clinical trial protocol

BACKGROUND

VAVASC study (Validation of Arterio Venous Access Stage Classification) is a multicentre, international, prospective study. The study aims to validate the AVAS classification, which is a classification system describing vascular status of patients indicated for creation of arteriovenous access on the upper limb.

METHODS

Observational, prospective, multicentre, international study starting in March 2021. Participant recruitment has commenced. Basic demographic data, risk factors and vascular mapping parameters are collected via an online platform. The outcome measures are class of AVAS, predicted arteriovenous access, final arteriovenous access that has been created and a functionality of the arteriovenous access. Predictive models will be used for statistical analysis.

CURRENT STATUS

A total of 140 patients from 4 centres in Great Britain, Czech Republic, Brazil and Slovakia are already included and undergoing evaluation.

CONCLUSIONS

The study is registered in the Clinical trials registry (NCT04796558), https://register.clinicaltrials.gov/. Study is still open for collaboration with other centres that can register via www.vavasc.com.

Sex hormones impact early maturation and immune response in the arteriovenous fistula mouse model

Arteriovenous fistulae (AVF) fail to mature more frequently in female patients compared with male patients, leading to inferior outcomes and decreased utilization. Since our mouse AVF model recapitulates sex differences in human AVF maturation, we hypothesized that sex hormones mediate these differences during AVF maturation. C57BL/6 mice (9-11 wk) were treated with aortocaval AVF surgery and/or gonadectomy. AVF hemodynamics were measured via ultrasound (days 0-21). Blood was collected for FACS and tissue for immunofluorescence and ELISA (days 3 and 7); wall thickness was assessed by histology (day 21). Inferior vena cava shear stress was higher in male mice (P = 0.0028) after gonadectomy, and they had increased wall thickness (22.0 ± 1.8 vs. 12.7 ± 1.2 µm; P < 0.0001). Conversely, female mice had decreased wall thickness (6.8 ± 0.6 vs. 15.3 ± 0.9 µm; P = 0.0002). Intact female mice had higher proportions of circulating CD3+ T cells on day 3 (P = 0.0043), CD4+ (P = 0.0003) and CD8+ T cells (P = 0.005) on day 7, and CD11b+ monocytes on day 3 (P = 0.0046). After gonadectomy, these differences disappeared. In intact female mice, CD3+ T cells (P = 0.025), CD4+ T cells (P = 0.0178), CD8+ T cells (P = 0.0571), and CD68+ macrophages (P = 0.0078) increased in the fistula wall on days 3 and 7. This disappeared after gonadectomy. Furthermore, female mice had higher IL-10 (P = 0.0217) and TNF-α (P = 0.0417) levels in their AVF walls than male mice. Sex hormones mediate AVF maturation, suggesting that hormone receptor signaling may be a target to improve AVF maturation.NEW & NOTEWORTHY After arteriovenous fistula creation, females have lower rates of maturation and higher rates of failure than males. In a mouse model of venous adaptation that recapitulates human fistula maturation, sex hormones may be mechanisms of the sexual dimorphism: testosterone is associated with reduced shear stress, whereas estrogen is associated with increased immune cell recruitment. Modulating sex hormones or downstream effectors suggests sex-specific therapies and could address disparities in sex differences in clinical outcomes.

Building a Scaffold for Arteriovenous Fistula Maturation: Unravelling the Role of the Extracellular Matrix

Vascular access is the lifeline for patients receiving haemodialysis as kidney replacement therapy. As a surgically created arteriovenous fistula (AVF) provides a high-flow conduit suitable for cannulation, it remains the vascular access of choice. In order to use an AVF successfully, the luminal diameter and the vessel wall of the venous outflow tract have to increase. This process is referred to as AVF maturation. AVF non-maturation is an important limitation of AVFs that contributes to their poor primary patency rates. To date, there is no clear overview of the overall role of the extracellular matrix (ECM) in AVF maturation. The ECM is essential for vascular functioning, as it provides structural and mechanical strength and communicates with vascular cells to regulate their differentiation and proliferation. Thus, the ECM is involved in multiple processes that regulate AVF maturation, and it is essential to study its anatomy and vascular response to AVF surgery to define therapeutic targets to improve AVF maturation. In this review, we discuss the composition of both the arterial and venous ECM and its incorporation in the three vessel layers: the tunica intima, media, and adventitia. Furthermore, we examine the effect of chronic kidney failure on the vasculature, the timing of ECM remodelling post-AVF surgery, and current ECM interventions to improve AVF maturation. Lastly, the suitability of ECM interventions as a therapeutic target for AVF maturation will be discussed.

Evaluating national guideline concordance of recurrent interventions after radiocephalic arteriovenous fistula creation

OBJECTIVE

Radiocephalic arteriovenous fistulas have been historically perceived as requiring multiple follow-up procedural interventions to achieve maturation and maintain patency. Recent clinical practice guidelines from the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) emphasize a patient-centered hemodialysis access strategy with new maximum targets for intervention rates, potentially conflicting with concomitant recommendations to prioritize autogenous forearm hemodialysis access creation. The present descriptive study seeks to assess whether radiocephalic fistulas can meet the KDOQI guideline benchmarks for interventions following access creation, and to elucidate clinical and anatomic characteristics associated with the timing and frequency of interventions following radiocephalic arteriovenous fistula creation.

METHODS

Prospective patient-level data from the multicenter PATENCY-1 and PATENCY-2 randomized trials, which enrolled patients undergoing new radiocephalic arteriovenous fistula creation, was analyzed (ClinicalTrials.govNCT02110901 and NCT02414841). The primary outcome was the rate of interventions at 1 year postoperatively. Incidence rates were calculated, and time to surgical or endovascular intervention following fistula creation was modeled using recurrent event extensions of the Cox proportional hazards model. Confidence intervals at the 95% level were calculated using nonparametric bootstrapping.

RESULTS

The cohort consisted of 914 patients; mean age was 57 years (standard deviation, 13 years), and 22% were female. Median follow-up was 707 days (interquartile range, 447-1066 days). The incidence of interventions per person-year was 1.04 (95% confidence interval [CI], 0.95-1.13) overall; 1.10 (95% CI, 0.98-1.21) before fistula use, and 0.96 (95% CI, 0.82-1.11) after fistula use. The most common interventions overall were balloon angioplasty (54.9% of all interventions), venous side-branch ligation (16.4%), and open revisions (eg, proximalization from snuffbox to wrist, 16.4%). The locations requiring balloon angioplasty included the juxta-anastomotic segment (51.7% of angioplasties), the outflow vein (29.2%), the inflow artery (14.8%), the central veins (3.8%), and the cephalic arch (0.5%). Common indications were to restore or maintain patency (75.6% of all interventions), assist maturation (14.9%), improve depth (4.4%), or improve augmentation (3.0%). In the multivariable regression analysis, female sex (adjusted hazard ratio [HR], 1.21; 95% CI, 1.05-1.45), diabetes (HR, 1.21; 95% CI, 1.01-1.46), and intraoperative vein diameter <3.0 mm (vs ≥4.0 mm: HR, 1.33; 95% CI, 1.02-1.66) were associated with earlier and more frequent interventions. Patients not on hemodialysis at the time of fistula creation underwent less frequent interventions (HR, 0.69; 95% CI, 0.59-0.81).

CONCLUSIONS

Patients with radiocephalic arteriovenous fistulas can expect to undergo one intervention, on average, in the first year after creation, which aligns with current KDOQI guidelines. Patients already requiring hemodialysis, female patients, patients with diabetes, and patients with intraoperative vein diameters <3.0 mm were at increased risk for repeated intervention. No subgroup exceeded guideline-suggested maximum thresholds for recurrent interventions. Overall, the results demonstrate that creation of radiocephalic arteriovenous fistula remains a guideline-concordant strategy when part of an end-stage kidney disease life-plan in appropriately selected patients.

Radiocephalic Arteriovenous Fistula Patency and Use

We sought to confirm and extend the understanding of clinical outcomes following creation of a common distal autogenous access, the radiocephalic arteriovenous fistula (RCAVF).

Mini-abstract: In this post hoc analysis of randomized clinical trial data including 914 adults with chronic kidney disease, the most robust predictors of radiocephalic arteriovenous fistula patency were larger cephalic vein diameter and access creation prior to a chronic hemodialysis requirement. Successful use occurred at increased rates in men, patients with larger diameter cephalic veins, smaller diameter arteries (albeit ≥2 mm), and when accesses were created using regional anesthesia and at higher volume centers.

Contemporary Strategies to Promote Dialysis Access Fistula Maturation

Background: The inability of a newly created arteriovenous fistula to support hemodialysis due to non-maturation results in increased complications secondary to catheter dependence. Methods: In view of the highly variable approaches by providers with heterogenous backgrounds (general surgery, vascular surgery, interventional radiology and interventional nephrology, urology, transplant surgery, etc.) we sought to describe a collection of algorithms that have functioned well in our hands to manage this challenging clinical problem and guide trainees and practicing clinicians alike.Results: Physical examination along with selective duplex ultrasound and fistulogram can identify most pathologies underlying non-maturation.Conclusion: Both endovascular and open techniques can be employed to optimize maturation rates in this complex population.

Effect of Radiocephalic Anastomotic Length on the Maturation of Arteriovenous Fistula

BACKGROUND

A radiocephalic arteriovenous fistula (RCAVF) is associated with better long-term patency and fewer complications. However, RCAVF have lower maturation rate for hemodialysis compared with upper AVF or arteriovenous graft. We performed this study to determine the effect of the radiocephalic (RC) anastomotic length on the AVF maturation.

METHODS

We reviewed the patients who underwent RCAVF creation with a side-to-end manner from March 2015 to December 2018. AVF maturation was defined as successful hemodialysis (HD) in at least two consecutive sessions. We compared the possible factors including the RC anastomotic length between the initial HD success group and initial HD failure group.

RESULTS

A total of 114 patients underwent RCAVF creation: 72 males and 42 females (63.2% and 36.8%, respectively). The mean preoperative arteriotomy length of the AVF was 14.1 mm (range 11.0-16.0 mm). Out of 114 patients, initial HD was executed successfully in 83 patients (72.8%). Among the 31 patients with initial HD failure (27.2%) balloon angioplasty was successfully performed in 17 patients, failed in 4 patients, and not performed in 10 patients. The secondary success rate after balloon angioplasty was 87.7%. After factor analysis, pre-emptive AVF (P = 0.01), vein diameter (P < 0.001), and flow rate (P < 0.001) were revealed significant factors for initial HD success, but not RC anastomotic length of AVF (P = 0.55).

CONCLUSION

The length of the radiocephalic anastomosis does not affect the RCAVF maturation rate statistically. However, lengthening of arteriotomy on the radial artery may increase the initial success rate of HD.

Factors associated with functional arteriovenous fistula at hemodialysis start and arteriovenous fistula non-use in a single-center cohort

BACKGROUND

The gold standard of commencing hemodialysis with a functional arteriovenous fistula (AVF) is challenging. We aim to review factors associated with functional AVF at hemodialysis start at a tertiary hospital.

METHODS

We retrospectively reviewed incident hemodialysis patients or who had AVF creation at a single tertiary hospital from 2011 to 2016. Data was extracted for patient comorbidities, duration from referral to AVF creation and hemodialysis start, estimated glomerular filtration rate (eGFR) at surgical referral, referring nephrologist, events accelerating eGFR decline, and revisions for "failing to mature" AVF to assess factors associated with non-functioning AVF or late AVF creation, using multinomial logistic regression.

RESULTS

Two hundred two patients received hemodialysis and 51 had AVF creation but did not dialyze (AVF futility rate 20%). Of these, 133 (66%) commenced hemodialysis with a central venous catheter (CVC) and 69 (34%) with an AVF. Patients with functional AVFs at hemodialysis start were referred earlier than those with non-functional AVFs (median 256 vs 66 days before hemodialysis start, p = 0.001). Age, sex, eGFR at surgical referral, and comorbidities were not predictive of patients with functional AVFs. Events accelerating eGFR decline were associated with an increased incidence of CVC at hemodialysis start (risk ratio (RR) 4.21, 95% confidence interval (CI) 1.96-9.03, p < 0.0001). Referring nephrologists external to our renal unit may be associated with non-functional AVF at hemodialysis start (RR 6.60, 95% CI 1.74-25.13, p = 0.006).

CONCLUSIONS

We found that functional AVFs required referral a median of 256 days prior to hemodialysis start and events accelerating eGFR decline increase the incidence of CVC at hemodialysis start. Age, sex, eGFR at surgical referral, and comorbidities did not inform the likelihood of timely AVF creation and evaluation of further predictive pre-dialysis factors is necessary to identify patients requiring early AVF creation whilst minimizing the cost of unnecessary procedures.

Sterile inflammation in the pathogenesis of maturation failure of arteriovenous fistula

Chronic kidney disease is a widespread terminal illness that afflicts millions of people across the world. Hemodialysis is the predominant therapeutic management strategy for kidney failure and involves the external filtration of metabolic waste within the circulation. This process requires an arteriovenous fistula (AVF) for vascular access. However, AVF maturation failures are significant obstacles in establishing long-term vascular access for hemodialysis. Appropriate stimulation, activation, and proliferation of smooth muscle cells, proper endothelial cell orientation, adequate structural changes in the ECM, and the release of anti-inflammatory markers are associated with maturation. AVFs often fail to mature due to inadequate tissue repair and remodeling, leading to neointimal hyperplasia lesions. The transdifferentiation of myofibroblasts and sterile inflammation are possibly involved in AVF maturation failures; however, limited data is available in this regard. The present article critically reviews the interplay of various damage-associated molecular patterns (DAMPs) and the downstream sterile inflammatory signaling with a focus on the NLRP3 inflammasome. Improved knowledge concerning AVF maturation pathways can be unveiled by investigating the novel DAMPs and the mediators of sterile inflammation in vascular remodeling that would open improved therapeutic opportunities in the management of AVF maturation failures and its associated complications.

Patency Outcomes of Arteriovenous Fistulas and Grafts for Hemodialysis Access: A Trade-Off between Nonmaturation and Long-Term Complications

Background

Arteriovenous fistulas (AVFs) for hemodialysis (HD) are often associated with better outcomes than arteriovenous grafts (AVGs). We aimed to investigate vascular access (VA) outcomes and assessed if AVF nonmaturation outweighs long-term complications of AVGs.

Methods

In this multicenter, retrospective cohort study in The Netherlands, 1- and 3-year primary, primary assisted, secondary, and functional patency rates were calculated, and the incidence of adverse events and procedures was assessed. Functional patency of RCAVFs, upper arm AVFs, and AVGs was compared using Cox analyses.

Results

In total, 1041 patients who received their first VA were included, of whom 863 had VAs that successfully matured. These patients were analyzed with a median follow-up of 25 months. The 1-year functional patency rates were 67%±2.0% for RCAVFs, 83%±2.0% for upper arm AVFs, and 85%±3.5% for AVGs. Three-year functional patency rates were 62%±2.0% for RCAVFs, 74%±2.0% for upper arm AVFs, and 69%±5% for AVGs. AVGs required more procedures per year (3.3 per year) of functional patency when compared with upper arm AVFs (1.8 per year).

Conclusions

The functional patency of AVFs and AVGs is comparable, although AVGs required more interventions to maintain usability for HD. The choice of VA is a trade-off between short-term advantages, favoring AVGs, and long-term advantages, favoring AVFs. Which VA is most appropriate depends on the patient's prognosis and preferences.

Higher Surgeon Procedure Volume is Associated with Improved Hemodialysis Vascular Access Outcomes

The objective of this study was to examine the association between surgeon characteristics, procedural volume, and short-term outcomes of hemodialysis vascular access. A retrospective cohort study was performed using Medicare Part A and B data from 2007 through 2014 merged with American Medical Association Physician Masterfile surgeon data. A total of 29,034 procedures met the inclusion criteria: 22,541 (78%) arteriovenous fistula (AVF) and 6,493 (22%) arteriovenous graft (AVG). Of these, 13,110 (45.2%) were performed by vascular surgeons, 9,398 (32.3%) by general surgeons, 2,313 (8%) by thoracic surgeons, 1,517 (5.2%) by other specialties, and 2,696 (9.3%) were unknown. Every 10-year increase in years in practice was associated with a 6.9 per cent decrease in the odds of creating AVF versus AV G ( P = 0.02). Surgeon characteristics were not associated with the likelihood of vascular access failure. Every 10-procedure increase in cumulative procedure volume was associated with a 5 per cent decrease in the odds of vascular access failure ( P = 0.007). There was no association of provider characteristics or procedure volume with survival free of repeat AVF/AVG or TC placement at 12 months. A significant portion of the variability in likelihood of creating AVF versus AVG is attributable to the provider-level variation. Increase in procedure volume is associated with decreased odds of vascular access failure.

Predictors of Primary Functional Maturation of Autogenous Radiocephalic Arteriovenous Fistula in a Cohort of Asian Patients

BACKGROUND

The aim of this study was to investigate the predictors of autogenous radiocephalic arteriovenous fistula (RCAVF) maturation.

METHODS

This was a retrospective analysis of patients undergoing RCAVF creation from June 2013 to December 2018 at a single medical center. Comparison of the variables between the matured and nonmatured group was performed.

RESULTS

A total of 277 patients (men, 173; 62.5%) with a mean age of 56.6 ± 16.9 years underwent primary RCAVF creation during the study period. The mean diameter of the cephalic vein and radial artery were 2.4 ± 0.6 mm (range 1.5 to 4.3 mm) and 2.3 ± 0.5 mm (range 1.5 to 4.0 mm), respectively. Primary functional maturation was achieved in 236 patients (236/277, 85%). There was no statistical significance between the matured and nonmatured group in terms of age (56.4 ± 14.8 vs. 58.1 ± 15.1, respectively; P = 0.498), coronary arterial disease (12% vs. 17%, respectively; P = 0.449), diabetes mellitus (42% vs. 39%, respectively; P = 0.864), smoking (26% vs. 22%, respectively; P = 0.699), or antiplatelet therapy (23% vs. 24%, respectively; P = 0.844). However, female gender (35% vs. 54%, respectively; P = 0.024), peripheral arterial disease (9% vs. 22%, respectively; P = 0.025), and small vein (2.4 ± 0.5 mm vs. 2.0 ± 0.5 mm, respectively; P < 0.01) and artery (2.4 ± 0.5 vs. 2.1 ± 0.4, respectively; P < 0.01) diameter were associated with the failure of maturation. The best cutoff diameter for the cephalic vein and radial artery was 1.85 mm and 2.05 mm, respectively.

CONCLUSIONS

In this cohort of patients undergoing RCAVF creation, vein and artery diameter on preoperative ultrasound mapping was the predictor of functional maturation. Female gender and presence of peripheral arterial disease were associated with failure of maturation.

Endovascular salvage of non-maturing autogenous arteriovenous fistulas by using angioplasty and competitive vein embolization

INTRODUCTION

The aim of this study is to evaluate the maturation and patency rates after endovascular treatment of non-maturing arteriovenous fistulas with percutaneous transluminal angioplasty, embolization of competitive veins, or a combination of both in a series of consecutive patients.

MATERIAL AND METHODS

Retrospective evaluation of patients with non-matured arteriovenous fistulas treated in our hospital was performed. Fistulography and ultrasonography was performed in all patients to evaluate the presence of stenosis and competitive veins. Significant stenoses (> 50%) were treated with balloon angioplasty and competitive veins (accessory and collateral veins) with coil embolization.

RESULTS

A total of 78 fistulas were treated. Angioplasty and coil embolization were performed in 73 and 51 patients, respectively. No major complications occurred. In 65 out of 78 arteriovenous fistulas (83%), successful cannulation with two needles was possible after endovascular treatment. Sixty-three arteriovenous fistulas (81%) were used successfully for at least 3 months. Accessory veins were the only lesion present in 14% of the arteriovenous fistulas; coil embolization of these accessory veins resulted in 100% successful maturation. The estimated 3, 6, and 12 months postintervention assisted primary patency rates were, respectively, 73%, 55%, and 45%. The estimated 3, 6, and 12 months postintervention secondary patency rates were, respectively, 81%, 78%, and 73%.

CONCLUSION AND DISCUSSION

Angioplasty and coil embolization are successful and safe procedures that can convert a non-mature fistula into a mature one in more than 80% of patients. Accessory vein embolization may be more important than collateral vein embolization in the presence of stenosis.

Higher Surgeon Procedure Volume Is Associated with Improved Hemodialysis Vascular Access Outcomes

The objective of this study was to examine the association between surgeon characteristics, procedural volume, and short-term outcomes of hemodialysis vascular access. A retrospective cohort study was performed using Medicare Part A and B data from 2007 through 2014 merged with American Medical Association Physician Masterfile surgeon data. A total of 29,034 procedures met the inclusion criteria: 22,541 (78%) arteriovenous fistula (AVF) and 6,493 (22%) arteriovenous graft (AVG). Of these, 13,110 (45.2%) were performed by vascular surgeons, 9,398 (32.3%) by general surgeons, 2,313 (8%) by thoracic surgeons, 1,517 (5.2%) by other specialties, and 2,696 (9.3%) were unknown. Every 10-year increase in years in practice was associated with a 6.9 per cent decrease in the odds of creating AVF versus AVG (P = 0.02). Surgeon characteristics were not associated with the likelihood of vascular access failure. Every 10-procedure increase in cumulative procedure volume was associated with a 5 per cent decrease in the odds of vascular access failure (P = 0.007). There was no association of provider characteristics or procedure volume with survival free of repeat AVF/AVG or TC placement at 12 months. A significant portion of the variability in likelihood of creating AVF versus AVG is attributable to the provider-level variation. Increase in procedure volume is associated with decreased odds of vascular access failure.

A systematic review, meta-analysis, and meta-regression of the efficacy and safety of endovascular arteriovenous fistula creation

OBJECTIVE

The percutaneous endovascular approach to arteriovenous fistula (AVF) creation is a minimally invasive alternative to surgical AVF creation. This systematic review and meta-analysis aimed to investigate the efficacy and safety of endovascular AVF creation in patients with end-stage renal disease.

METHODS

This study conformed to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. An electronic search was performed on major databases to identify relevant articles. Meta-analysis of proportions and meta-regression were conducted.

RESULTS

Seven studies totaling 300 patients were included, of which four evaluated the everlinQ (TVA Medical, Austin, Tex) and three employed the Ellipsys (Avenu Medical, San Juan Capistrano, Calif) systems. The overall technical success rate was 97.50% (95% confidence interval [CI], 94.98-99.31%; I² = 0.00%; P = .487). The 90-day maturation rate was 89.27% (95% CI, 84.00-93.66%; I² = 21.29%; P = .283), and the 6-month patency and 12-month patency were 91.99% (95% CI, 87.98-95.35%; I² = 0.00%; P = .780) and 85.71% (95% CI, 79.90-90.71%; I² = 0.00%; P = NS), respectively. The overall procedure-related complication rate was 5.46% (95% CI, 0.310-14.42%; I² = 81.21%; P = .000). Meta-regression was conducted on the pooled rates of technical success and complication, showing that age, diabetes, white race, hypertension, on dialysis, and body mass index were not significant sources of heterogeneity.

CONCLUSIONS

Current endovascular AVF systems appear to be effective and safe. However, given the lack of head-to-head comparative analyses with surgical AVF creation, superiority cannot be established.

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.

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.