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.

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.

Patency Rates and Outcomes of Renal Access Arteriovenous Fistulas for Hemodialysis in Patients with Chronic Kidney Disease

Hemodialysis remains the most popular modality of renal replacement therapy for end-stage renal disease patients with chronic kidney disease. Various factors such as a radial artery, cephalic vein diameter, age, hypertension, and diabetes mellitus can affect the fistula maturation. This study was carried out to know the patency rates and factors affecting fistula maturation in the Indian population. This is a prospective observational study which aimed to study the patency rate of arteriovenous (AV) fistulas. On the day of surgery, patients were shifted inside the operation theater. Under all aseptic precautions, an AV fistula was formed using the radial artery and cephalic vein. All patients were followed up for 6 months. The data were analyzed using IBM SPSS version 22. To see the change over a period of time, McNemar test for categorical data and repeated measure for continuous data followed by post hoc comparison by Bonferroni method were used. The mean age of the patients was 46.98 ± 13.33 years. The mean diameter of the cephalic vein, ulnar artery, and radial artery at the wrist was 1.733 ± 0.528, 1.700 ± 0.364, and 1.908 ± 0.420, respectively, whereas the mean diameter of the cephalic vein, ulnar artery, and radial artery at the forearm was 1.952 ± 0.488, 1.910 ± 0.421, and 2.058 ± 0.458, respectively. Immediate thrill after the surgery was present in 36/52 (69.2%) of the patients. The radial artery diameter at the wrist was significantly less in the patients with primary failure in whom immediate thrill was not present (P = 0.016). At 1-month follow-up, 30/49 (61.2%) and, at 6 months, 29/48 (60.4%) fistulas were functional. Radiocephalic AV fistulas have a reasonable success rate and minimal morbidity, and radial artery diameter is a good predictor of the outcome.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

DISCUSSION

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

Outcome of Permanent Vascular Access with Vein ≤ 2.2 mm in Diameter

OBJECTIVE

End-stage renal disease patients with vein diameter of ≤2.2 mm can undergo autogenous arteriovenous fistula (AVF) formation with the acceptable results.

METHODS

This observational retrospective study of prospectively collected data analyzed end-stage renal disease patients with a vein diameter of ≤ 2.2 mm, who underwent AVF formation at Shifa International Hospital Islamabad from January 2009 to December 2017. The fistulae were observed for immediate success and maturity at 3 months. The chi-square test was used to determine the effect of vein diameter on final maturity. All data were analyzed using SPSS.

RESULTS

The total number of patients with vein diameter of ≤2.2 mm was 38, with a mean age of 46.76 ± 12.790 years. Vein diameters ranged from 1.6 to 2.2 mm. Immediate success was observed in 35 (92.1%) cases. Veins of 31 (81.6%) patients showing maturity at 3 months and were used for hemodialysis. The overall success rate for the small caliber veins was 82%.

CONCLUSION

Although end-stage renal disease patients present late with very small diameter veins, these veins should still be accommodated for permanent vascular access, because their maturity rates are still acceptable, even though these are lower than those of patients with adequate sized veins.

High low-density lipoprotein cholesterol level is the independent risk factor of primary patency rate of arteriovenous fistula

OBJECTIVES

An arteriovenous fistula is the first choice of vascular access in dialysis patients. However, the correlations between patient factors and the arteriovenous fistula patency rate remain unclear. Therefore, we examined the effect of dialysis patient factors on arteriovenous fistula patency rate.

METHODS

This study included 101 patients who received maintenance dialysis and used arteriovenous fistula for vascular access at Atami Hospital, International University of Health and Welfare in July 2018. A retrospective review was performed from the time of arteriovenous fistula creation to July 2018, and the primary and secondary arteriovenous fistula patency rates were investigated. The patency rate was calculated using the Kaplan-Meier method, and risk factor analysis was performed using Cox proportional hazards regression analysis.

RESULTS

The primary patency rate of arteriovenous fistula was 71.2% at one year and 43.0% at five years, and the secondary patency rate was 92.7% at one year and 79.8% at five years. In the multivariate analysis, high low-density lipoprotein cholesterol (LDL-C) level and a history of diabetes were considered significant risk factors (HR 1.023, p value <0.01 and HR 2.550, p value <0.01, respectively). A log rank test was conducted on the groups of patients with LDL <90 mg/dl and LDL ≥90 mg/dl, and the <90 mg/dl group resulted in a good primary patency rate (p value 0.0327).

CONCLUSIONS

High LDL-C level was considered the independent risk factors of arteriovenous fistula primary patency rate.

Determinants of successful arteriovenous fistulae creation including intraoperative transit time flow measurement

BACKGROUND

The prevalence of hemodialysis patients is increasing, and it is important to create the arteriovenous fistula as early as possible to avoid hemodialysis by central venous catheter. International guidelines recommend arteriovenous fistula as the vascular access of first choice. Arteriovenous fistulae are associated with a failure rate of 23%. The success of an arteriovenous fistula can be evaluated intraoperatively by physical examination and by measuring the blood flow.

OBJECTIVES

The aim of the study is to describe the predictive value of various factors for fistula maturation in the context to the current literature.

METHODS

We report on a prospective cohort study of 41 patients, undergoing a primary arteriovenous fistula at the upper extremity. The primary endpoint of the study was the successful fistula maturation after 6 weeks.

RESULTS

The intraoperative measurement of the blood flow in the outflow vein has been identified as the unique significant parameter for the fistula maturation.

CONCLUSION

The predictive value of intraoperative flow measurement is superior to intraoperative physical examination and could help reduce the fistula dysmaturation rate. Intraoperative transit time flow measurement is an easy method and can be used to predict successful fistula maturation in a high percentage rate.

Influence of intraoperative findings on immediate flow through radial-cephalic arteriovenous wrist fistulas for hemodialysis access

Background

Adequate flow through a newly created arteriovenous fistula depends on multiple characteristics of the vessels and patient comorbidities. Several studies have related preoperative findings to failure, but few have analyzed the influence of intraoperative findings.

Objectives

To evaluate the predictive value of intraoperative findings on the immediate outcome of radial-cephalic arteriovenous wrist fistulas (RCAVF) by collecting data that are easily measured intraoperatively.

Methods

We designed a cross-sectional study, in which a single surgeon performed 101 RCAVF in 100 patients at a single center. We analyzed the immediate postoperative flow, assessed by thrill intensity immediately after fistula creation, against patient demographics and intraoperative data. The following variables were analyzed: age, sex, comorbidities, length of vein visible at preoperative examination, macroscopic arterial calcification, maximum vein diameter, and length of stenosis-free vein, measured by cannulation with a urethral catheter during the procedure. The chi-square test was used both to eliminate possible bias introduced by side of venous access (left or right), and to determine predictive values of immediate thrill.

Results

Side of access was not associated with any significant differences in variables. Absence of macroscopic arterial calcification, successful venous catheterization using a 6 French catheter or larger, and ability to advance it more than 10 centimeters along the lumen of the proximal vein were correlated with adequate immediate postoperative thrill (p = 0.004, p < 0.001, and p = 0.005, respectively).

Conclusions

In this series of 101 RCAVF, both the diameter of the catheter and its progress through the proximal vein and also absence of arterial calcification had positive predictive value for achieving adequate immediate thrill after vascular access construction.

Predictors of Radio-cephalic Arteriovenous Fistulae Patency in an Asian Population

Purpose

To identify predictors of arteriovenous fistula (AVF) patency in Asian patients with autogenous radio-cephalic arteriovenous fistula (RCAVF).

Methods

Retrospective review of 436 RCAVFs created between 2009 and 2013. Predictors of patency were identified with univariate and multivariate analysis. Kaplan-Meier survival analysis and log-rank test were used to calculate patency rates.

Results

Overall secondary patency rate was 72% at 12 months, 69% at 24 months, 58% at 36 months, 57% at 48 months, 56% at 60 months and 54% at 72 months. Univariate analysis showed that factors which predict for patency include male gender (p = 0.003), good diabetic control (p = 0.025), aspirin use (p = 0.031), pre-dialysis status (p = 0.037), radial artery diameter (p = 0.029) and non-calcified radial arteries (p = 0.002). Age (p = 0.866), cephalic vein diameter (p = 0.630) and surgeon grade (p = 0.472) did not predict for primary AVF failure. Multivariate analysis revealed the male gender to be an independent predictor for patency (odds ratio 1.99, p = 0.01). Subset analysis showed a significantly larger average radial artery diameter of 2.3 mm amongst males, as compared to 1.9 mm amongst females (p = 0.001) and no statistical difference in the average cephalic vein diameter.

Conclusions

Within our Asian study population, 12-month patency rate of RCAVF is 72%, 69% at 24 months, 58% at 36 months, 57% at 48 months, 56% at 60 months and 54% at 72 months. Male gender is an independent predictor for RCAVF patency. In females or patients with calcified radial arteries, a more proximal AVF should be considered.

Impact of surgeon factor on radiocephalic fistula patency rates

INTRODUCTION

Hemodialysis with arteriovenous fistula (AVF) has been widely accepted treatment modality for patients with chronic renal failure (CRF). Radiocephalic fistulas are considered to be the most desirable for the initial vascular access. The aim of this study is to investigate the surgeon factor on radiocephalic fistula patency rates.

METHODS

A total of 186 patients with diagnosis of CRF underwent Radiocephalic fistula for hemodialysis access were included. Patients were divided into 2 groups according to operating surgeon. Patients were evaluated according to demographic characteristics, secondary patency rates, second AVF creation and complications.

RESULTS

Mean age was 57.7 ± 14.8 years. The most common etiology of CRF was idiopathic (66.6%). 40 (75.5%) patients in group 1 and 122 (91.7%) patients in group 2 were pre-dialysis patients (p < 0.05). Overall secondary patency rate was 77.4%. Patients in group 1 and group 2 have secondary patency rates of 83% and 75.2%, respectively (p = 0.458). Second AVF creation was done in 2 (3.8%) patients in group 1 and 23 (17.3%) patients in group 2 (p < 0.05). Postoperative complication rate was 9.6%.

CONCLUSION

Operating surgeon is not a major factor of secondary patency in radiocephalic arteriovenous fistulas.

The Reasons for the Failure of the Primary Arteriovenous Fistula Surgery in Patients with End-Stage Renal Disease

Purpose

To analyze the reasons for the failure of the primary arteriovenous fistula surgery and explore preventive measures.

Methods

A total of 819 patients with end-stage renal disease were enrolled in the study. Autologous arteriovenous fistula surgery was performed on all patients. Their clinical data of hemoglobin (HB), albumin (ALB), cholesterol (CHOL), parathyroid hormone (PTH), blood glucose and blood pressure were collected before surgery, while the diameters of the radial artery and cephalic vein were measured by ultrasound.

Results

The operations in 742 patients were successful, but failed in 77 cases (accounting for 7.07%). The failure group was significantly older (61.3 ± 13.4 years) than the successful group (45.6 ± 11.2 years). The ratio of diabetes 36 (46.8%) and hypertension 20 (26.0%) was significantly higher in the failure group than in the successful group, respectively 235 (31.7%) and 145 (19.5%). The patients with blood pressure below 120/70 mm Hg had a higher risk of failed surgery (36.4%) than those with blood pressure above 120/70 mm Hg (9.16%). The cephalic vein and radial artery diameters were significantly smaller in the failure group (1.35 ± 0.64 mm, 2.13 ± 0.81 mm) than in the successful group (1.98 ± 0.47 mm, 2.47 ± 0.74 mm); the PTH levels in the failure group were significantly higher (782.39 ± 423.85) than in the successful group (378.83 ± 352.21).

Conclusions

The autogenous arteriovenous fistula surgery failure highly correlated with the patient's age, blood pressure, the primary disease and the vessel diameter. In addition, the PTH levels had a certain correlation with the failure of the fistula surgery.

Predicting Outcomes in Native AV Forearm Radio-cephalic Fistulae; the CAVeA2T2 Scoring System

Purpose

The aim of this study was to identify significant factors relating to fistula survival and create an easy-to-use scoring system for predicting fistula patency rates.

Methods

A total of 276 consecutive radio-cephalic forearm fistulae created in a single tertiary vascular unit were identified retrospectively. Numerous patient- and fistula-related demographics were noted. Cox regression analysis was used to identify significant factors predictive of reduced fistula patency rates, and significant variables weighted according to their hazard ratio.

Results

Five significant factors were identified: ipsilateral Central venous access, Age >73 years, anastomosed Vein <2.2 mm, previous lower limb Angioplasty and absent intraoperative Thrill (1 point for first three variables, 2 points for the latter two). The CAVeA2T2 score (maximum 7 points) significantly predicted for reduced fistula patency (p = 0.001) and a reduced rate of successful dialysis (p = 0.001). Fistulae with CAVeA2T2 scores ≥2 had 6 week and 1 year patency rates significantly below pooled published rates. Without scoring for thrill, that is in the pre-operative setting, the scoring system remained significant at all stages.

Conclusion

The CAVeA2T2, scoring system is a potential scoring system for predicting fistula patency rates and the likelihood of dialysing through a fistula. Further studies and/or external validation is required in the context of methodological limitations. How to manage patients with a high CAVeA2T2 score is unknown.

A review of patients with renal disease undergoing vascular access surgery: is gray-scale ultrasound enough?

BACKGROUND

An adequate fistula or graft is essential to long-term survival and quality of life for patients with end-stage renal disease (ESRD) who are receiving hemodialysis because of its lower complication rates, lower costs, and prolonged patency. Use of duplex ultrasound for preoperative planning is currently recommended by the Kidney Disease Outcomes Quality Initiative for patients with ESRD with prior fistulas or grafts, central lines, pacemakers, and prior chest or arm surgery. The preoperative evaluation consisted of gray-scale ultrasound and physical examination in all patients with ESRD in this study. The current study determined the baseline data, including the type of vascular access, functional patency of access, associated morbidity, and preoperative demographics and comorbidities, including prior dialysis access. The primary objective was to determine the frequency of revision surgery, to identify the potential cases that may indicate the need for better assessments (eg, duplex ultrasound), and to improve fistula and graft success rates.

MATERIALS AND METHODS

A retrospective chart review of patients with ESRD who underwent native fistula or graft access creation in a 13-month time period from 2010 to 2011 was completed. Seventy-six surgical procedures were performed on 53 subjects. Included variables were age, race, gender, smoking status, body mass index, stage of chronic kidney disease at referral, previous central lines/pacemakers, fistulas, or grafts. Comorbidities identified included diabetes mellitus (DM), hypertension (HTN), and coronary artery disease (CAD). The types of access, location, maturation, infection, failure, or revision were noted. Continuous variables are shown in frequencies and mean. Categoric data were compared using chi-square analysis.

RESULTS

During the 13-month study period, 76 surgical procedures were performed in 53 patients, with 39.6% of patients undergoing multiple surgical procedures. The majority of patients were male (98%) and white (58.5%), with a history of HTN (96.2%) and DM (64.2%). The mean age was 68 years, with most patients presenting in stage 5 chronic kidney disease (92.5%). Some 67.9% of patients had prior central lines or pacemakers; of those, 56.6% had previous fistulas or grafts. Negative significance was determined between the comorbidities DM/HTN/CAD alone or grouped as a cohort and multiple surgeries. Positive significance was found between multiple surgical procedures and those with prior access/pacemaker/central line (chi-square [1, N = 53] = exact P = .04).

CONCLUSIONS

Patients with ESRD undergoing access creation presenting with prior central lines, pacemakers, or arm surgery (fistulas or grafts) were more likely to undergo multiple surgeries to obtain a functional graft or fistula for hemodialysis use than those patients with ESRD without prior central lines, pacemakers, or arm surgery (fistulas or grafts). Color duplex ultrasound should be considered as a standard for preoperative assessment in an effort to improve fistula or graft success rates.

Radiocephalic fistula: review and update

Since initially described in 1966, radiocephalic fistula or Brescia-Cimino fistula is one of the most commonly performed fistulas in the world of arteriovenous access. The indications for insertion include, but are not limited to, hemodialysis. Although this is a frequently performed procedure, the primary and secondary patency rates and predictors of failure are not well defined. The review of this topic is difficult because of the diversity in reporting and the absence of consensus between series. Following the current published recommendations by the Society of Vascular Surgery regarding standardization of terminology to facilitate meaningful comparison between the diversity of published data, this review is an attempt to summarize and highlight the relevant information with regard to primary patency, secondary patency, and predictors of failure of radiocephalic fistula using the available English literature.

Irreversible sequela in an arterial venous fistula with steal syndrome: a case study

Arteriovenous fistulas may be susceptible to steal syndrome from a variety of conditions. Steal syndrome is defined as arterial insufficiency distal to the arteriovenous fistula. The causality of the insufficiency may include arterial disease proximal or distal to the fistula, markedly high blood flow volume after creation, or undetected collateral flow. Prior arterial disease may expose insufficient profusion to the distal extremity after fistula creation. High blood flow volume immediately after fistula creation may perhaps cause steal syndrome symptoms, but this often resolves with fistula maturation. Undetected collateral flow, or side branches, from target vessels receive increased blood volume after fistula creation and expand, thereby stealing blood flow from the hand. This particular condition can potentially cause ischemic changes distal to the fistula with potentially irreversible sequela if not recognized in a timely manner. A sixty- one year old male, sent with chest pain to the emergency room from his dialysis center, was found to have steal syndrome with an accompanying motor deficit. The diagnosis of steal syndrome is based on physical examination, patient history, and confirmation testing such as doppler ultrasound, digital pressures or arteriogram. A thorough preoperative workup and careful postoperative monitoring can minimize steal syndrome and prevent permanent impairment.

Factors affecting the patency of arteriovenous fistulas for dialysis access

BACKGROUND

The autologous arteriovenous fistula (AVF) is the accepted gold standard mode of repeated vascular access for hemodialysis in terms of access longevity, patient morbidity, and health care costs. This review assesses the current evidence supporting the role of various patient and surgeon factors on AVF patency.

METHODS

The literature was searched to identify the current evidence available for patient characteristics, methods of AVF planning, and anatomic factors that may affect patency outcomes after AVF formation. The use of adjuvant medications, surgical techniques, and policies for AVF maintenance are discussed in relation to AVF patency.

RESULTS

Current literature supports patient factors, such as increasing age, presence of diabetes, smoking, peripheral vascular disease, predialysis hypotension, and vessel characteristics, as directly influencing AVF patency. Vessels of small caliber (<2 mm) or demonstrating reduced distensibility are unlikely to create a functional AVF. Current evidence does not support altered patency due to sex or raised body mass index (<35 kg/m(2)). Factors such as early referral for AVF, preoperative ultrasound vessel mapping, use of vascular staples, and intraoperative flow measurements affected AVF patency, but the use of medical adjuvant therapies did not. Programs of surveillance and various needling techniques to maintain patency are not supported by current evidence. Novel techniques of infrared radiotherapy and topical glyceryl trinitrate are possible future strategies to increase AVF patency rates. The limitations of available evidence include a lack of large, randomized controlled trials and meta-analysis data to support current practice.

CONCLUSIONS

There is a complex interaction of factors that may affect the patency of an individual AVF. These need to be carefully considered when selecting surgical site or technique, adjuvant treatments, and follow-up protocols for AVFs.