Endovascular Management of the “Failing to Mature” Arteriovenous Fistula

The role of a distal forearm perforating vein and deep vein system in supporting patency of a snuffbox fistula - A case report

The purpose of this manuscript is to describe the clinical course of a 66-year-old patient with chronic kidney disease due to focal segmental glomerulosclerosis in whom an access arteriovenous fistula was created in the anatomical snuffbox. At discharge, the fistula thrill was normal. Two months later, a duplex examination revealed previously unrecognized obstruction of the mid-forearm segment of the cephalic vein; flow was maintained by a perforator into the deep venous system, which returned blood to the upper arm cephalic vein above the occlusion. A second, subsequent radiocephalic anastomosis was performed in the wrist to augment flow. The fistula was successfully cannulated after 12 weeks of maturation.

Interwoven nitinol stent-assisted arteriovenous fistula maturation: 2 year-outcomes of a single center experience

OBJECTIVES

The aim of this study was to report 2-year outcomes of interwoven nitinol (SuperaTM) stent-assisted arteriovenous fistula (AVF) maturation in patients who presented with non-matured AVF.

METHODS

We reviewed the clinical data of 20 patients who presented with non-matured AVF (19 patients with brachiocephalic AVF and 1 patient with radiocephalic AVF) and underwent balloon angioplasty followed by SuperaTM stenting in the cephalic vein for long-term hemodialysis between January 2017 and January 2022. The outcomes were evaluated in these patients in terms of technical success, post-intervention complications, reintervention, and cumulative patency (6 months, 1 year, and 2 years).

RESULTS

The study included 20 patients who presented with non-matured AVF. The mean age of the patients was 65 years (range, 40-85). The SuperaTM stents of size 6.5 mm were used in 15 patients (75%), and those of 7.5 mm and 5.5 mm were used in 4 (20%) and 1 (5%) patient, respectively. The average stent length was 99.5 mm (range, 80-120). Technical success was achieved in all patients. Early use within 1 week by needling at the SuperaTM stent segment (cannulation zone) was successful in all patients without any complications. The mean follow-up time was 24.5 months. During the follow-up period, reinterventions to maintain the function of AVF were performed in 8 patients (40%) (7 patients with juxta-anastomotic stenosis, 1 patient with in-stent restenosis). The reintervention rate was 0.39 procedures per patient per year. The primary patency at 6 months, 1 year, and 2 years were 85.5%, 62.6%, and 54.2%, respectively. The assisted primary patency at 6 months, 1 year, and 2 years were 95%, 84.5%, and 78.8%, respectively.

CONCLUSIONS

The use of the SuperaTM stent to improve the AVF maturation rate was associated with acceptable outcomes at 2 years. Its benefit over other strategies was the early use of the access for hemodialysis.

Transjugular approach: comparison with conventional endovascular treatment of native arteriovenous fistulas

OBJECTIVES

The aim of this study was to compare the outcomes of the transjugular approach with those of the conventional approach for endovascular treatment of arteriovenous fistulas (AVFs).

METHODS

Between May 2015 and July 2019, 112 patients with endovascular treatment of dysfunctional or immature AVFs were included and divided into the transjugular (n = 46) and conventional (n = 66) groups. Electronic medical records and angiography of the patients were retrospectively reviewed to assess technical and clinical success rates, time to first fistulography, total procedure time, primary and secondary patency, and complications in both groups.

RESULTS

There were no significant differences in technical success rate (87.0% vs 97.0%; P = .062), clinical success rate (80.4% vs 90.9%; P = .109), or total procedure time (60.2 vs 57.9 min; P = .670) between the groups. Cox proportional hazards models showed that the cumulative primary patency was significantly higher in the transjugular group than in the conventional group (P = .041; 6-month patency rates, 93.8% vs 91.5%). Also, a statistically significant difference was found between the cumulative secondary patency of the groups (P = .014; 6-month patency rates, 91.4% vs 86.5%). No major complications were observed.

CONCLUSIONS

Transjugular endovascular treatment of AVFs was successful and effective. Longer patency periods were observed when treated via transjugular access.

ADVANCES IN KNOWLEDGE

This article compared the outcomes of transjugular approaches with those of conventional approaches in the endovascular treatment of native AVFs and showed higher patency periods/rates in the transjugular group than in the conventional group.

Arteriovenous fistulas for hemodialysis: Brief review and current problems

The number of people worldwide living with end-stage renal disease is increasing. Arteriovenous fistulas are the preferred method of vascular access in patients who will require hemodialysis. As the number of patients with arteriovenous fistulas grows, the role of physicians who intervene who maintain and salvage these fistulas will grow in importance. This review aims to familiarize practitioners with the rationale for arteriovenous fistula creation, the detection of fistula dysfunction, and the state of the art on fistula maintenance and preservation. Current controversies are briefly reviewed.

Monitoring the Patient Following Radio-Cephalic Arteriovenous Fistula Creation: Current Perspectives

Autogenous radial–cephalic direct wrist arteriovenous fistula (RC-AVF) in the non-dominant arm is the gold standard for dialysis vascular access. However, the RC-AVF non-maturation rate is significant (≃ 40%) due to an increasingly elderly and comorbid population incidence. A detailed identification of the biological cascade underlying arteriovenous fistula (AVF) maturation could be the key to clinical research aimed at identify the group of patients at risk of primary AVF failure. Currently, careful post-operative monitoring remains the most crucial aspect to overcome the problem of impaired maturation. Up to 80% of patients with immature RC-AVF have problems potentially solvable with early endovascular or surgical correction. Physical examination by experienced practitioners in conjunction with duplex ultrasound examination (DUS) can identify physical signs of non-maturation, understand the underlying cause, and drive for a tailored early planning to treat the complication. New approaches for the early assessment of AVF maturation are under study. Techniques to promote RC-AVF maturation performed through the administration of pre-or peri-operative drugs have missed up to now to prove an efficacy in improving fistula success. The new techniques tested after surgery appear to hold future promise for improving fistula maturation.

Maturation Rates of Arteriovenous Fistulas Using Small Veins in the Era of Endovascular Interventions

BACKGROUND

Traditional practice suggests the abandonment of veins smaller than 3 mm in diameter for arteriovenous fistula (AVF) creation because of a low rate of maturation. This study aims to show that with balloon-assisted maturation (BAM), undersized veins can be used to create functional AVFs with a high rate of success.

METHODS

All patients who underwent AVF creation between 2014 and 2018 at a tertiary academic medical center were retrospectively reviewed. The patients without preoperative vein mapping, those who failed to follow-up, and the patients who were not on dialysis were excluded. A fistula was considered to be mature if it was successfully cannulated for dialysis. A total of 596 patients were identified for analysis. The cohort was divided into the small-vein group (SVG, <2.5 mm) and large-vein group (LVG, ≥2.5 mm) based on preoperative vein size. Categorical variables were analyzed with the chi-squared test for their association with maturation status. Continuous variables were analyzed with the Wilcoxon rank sum test. A P-value less than 0.05 was considered significant.

RESULTS

In the study cohort, 61.9% of the patients were male, with an average age of 62.8 ± 13.7 years, and an average preoperative vein size of 2.9 ± 1.1 mm. With similar demographic distribution, the participants in the SVG (n = 216) had significantly smaller preoperative vein size of 1.9 ± 0.4 mm than the patients in the LVG (n = 380), 3.5 ± 0.8 mm (P = 0.001). There were significantly more radio-cephalic AVFs created in the SVG (77.8% versus 48.7%, P < 0.0001). The overall maturation rate was 83.1% (n = 495), 219 fistulas (36.7%) matured primarily and 276 (46.3%) required interventions. Ninety-one percent of the patients required only 1 or 2 BAMs to achieve maturation. The SVG achieved a maturation rate of 75.9% as compared with 87.1% in the LVG (P = 0.002). A significantly higher number of patients in the SVG required BAM for maturation as compared with the LVG (67.7% versus 49.9%, P = 0.0002); however, there was no difference in the average number of BAMs required for fistula maturation between the groups (1.5 ± 0.8 for the SVG vs. 1.4 ± 0.7 for the LVG). In multivariable logistic regression analysis, vein size ≥2.5 mm (odds ratio (OR) = 2.11, confidence interval (CI): 1.36-3.27, P = 0.0009) and male sex (OR = 2.30, CI: 1.49-3.57, P = 0.0002) were independent predictors of maturation.

CONCLUSIONS

Small veins can be used for AVF creation with lower but still favorable maturation rates using BAM interventions, especially in male patients. This practice can increase the creation of autogenous dialysis access and potentially reduce complications related to prosthetic dialysis access.

Radial artery diameterand and age related functional maturation of the radio-cephalic arteriovenous fistula

Background

Previous studies have not described the relationship between reducing radial artery diameter as well as increasing age and functional maturation of the radio-cephalic arteriovenous fistula (RCAVF) and no data identify these as linear relationship. The objective of this study was to perform trend analysis to assess these aspects.

Methods

Our retrospective cohort study enrolled and analyzed 353 follow-up cases that underwent first AVF creation. The artery and vein sizes were measured by ultrasound. We performed follow-up, a minimum of 3 months after surgery. Multivariable logistic regression analysis was used to identify independent risk factors inmaturation. Participant age was categorized into four groups (age ≤ 29, 30–49, 50–69, and 70–90 years). Radial artery diameter was categorized into four groups (≤ 1.9, >1.9 and ≤ 2.1, >2.1 and ≤ 2.4, >2.4 mm) according to median and interquartile ranges. We adjusted for confounders in four logistic models, and primary analyses were based on building ordered category models and tested P values for trends to estimate the relationship of radial artery diameter and each 20-year increase in age with risk of maturation.

Results

The mature RCAVF group included 301 cases, and the immature group included 52 cases. Radial artery diameter, age, and diabetes were independent risk factors of maturation. Odds ratios (ORs) associated with maturation reduced with increasing age, while ORs increased with increasing radial artery diameter. P values for trends(<0.05) were observed in all four models. A reduction in radial artery diameter and higher age were significantly associated with a higher incidence of immaturity after adjusting the multivariate models. The risks of immaturation were increased by more than 1.54 fold for each 20-year increase and increased by more than 1.34 fold for the smaller radial artery diameter group.

Conclusion

Our findings suggest that a significantly higher immaturity risk of RCAVF was associated with increasing age and a reduction in radial artery diameter. Our study identified a linear exposure-response relationship of age and radial artery diameter with immaturity incident. A careful selection of patients will be helpful in improving AVF functional maturation.

Study of Arteriovenous Fistula Cases in a Tertiary Care Hospital: A Descriptive Cross-sectional Study

INTRODUCTION

Arteriovenous fistulas are a preferred choice for hemodialysis access in chronic kidney disease patients. There is increased adoption of arteriovenous fistula creation in Nepal. Our objective is to study various arteriovenous fistulas that have been created in our center.

METHODS

This is a descriptive cross-sectional study conducted in a tertiary care hospital including all cases of arteriovenous fistula creation from January 2018 to December 2019. We obtained the ethical clearance from the institutional review committee of Kathmandu University School of Medical sciences. Convenient sampling method was used. Detailed vascular mapping and color doppler ultrasonography was done in the bilateral upper limb as preoperative preparation and to choose a site for arteriovenous fistula creation. Data were entered into the Statistical Package for the Social Sciences version 20 for analysis.

RESULTS

Among 50 patients, the most common location was brachiobasilic 20 (40%) patients followed by brachiocephalic 18 (36%), radiocephalic 11 (22%), and arteriovenous graft between the brachial artery and axillary vein 1 (2%). The mean duration of hospital stay was 1.44 days. Three (6%) patients required re-intervention, all within 24 hours. Two (4%) patients had a failure of arteriovenous fistula requiring the creation of a new arteriovenous fistula.

CONCLUSIONS

Brachiobasilic was the most common location for arteriovenous fistula creation. Reintervention was not common.

Transjugular percutaneous endovascular treatment of dysfunctional hemodialysis access

PURPOSE

To evaluate the feasibility and the outcomes of transjugular percutaneous endovascular treatment of dysfunctional hemodialysis access in patients with chronic kidney disease.

METHODS

A total of 50 transjugular treatments in 38 patients with arteriovenous fistulas or arteriovenous grafts from September 2011 to May 2015 were included in this study. Medical records and angiographies were retrospectively reviewed. Success rate, patency rate, procedure time, and complications including internal jugular vein stenosis were evaluated.

RESULTS

A total of 50 sessions of transjugular treatments were performed in 38 patients. There were 31 native arteriovenous fistulas including 10 immature cases and 19 arteriovenous grafts. Among the 50 cases, technical success was achieved in 45 and clinical success was achieved in 44; 37 cases (74%) with multiple stenotic sites were treated by the transjugular approach without placement of cross-sheaths. The mean time from puncture of the internal jugular vein to first fistulography was 10 min, and the mean total procedure time was 64 min. The primary patency rate at 6 months was 77%, while the secondary patency rate at 6 months was 97%. Perforation occurred in two cases during conventional percutaneous transluminal angioplasty after failure of the transjugular approach. One dissection occurred during the transjugular approach. There was no newly developed internal jugular vein stenosis during a mean follow-up period of 19.3 months.

CONCLUSION

For the treatment of dysfunctional or immature hemodialysis access, the transjugular approach is a feasible and effective option that avoids injury to the graft or draining vein, especially in immature fistulas.

Predictive parameters of arteriovenous fistula maturation in patients with end-stage renal disease

Background

The objevctive of the present study was to explore the potential influence of blood markers and patient factors such as risk factors, kidney function profile, coagulation profile, lipid profile, body mass index, blood pressure, and vein diameter on the maturation of arteriovenous fistula (AVF) in patients with end-stage renal disease.

Methods

Retrospective data from 300 patients who had undergone AVF creation at the Royal Infirmary of Edinburgh were examined. A predictive logistic regression model was developed using a backward stepwise procedure. Model performance, discrimination, and calibration were assessed using the receiver operating characteristic (ROC) curve and Hosmer–Lemeshow goodness-of-fit test. The final model was externally validated by 100 prospective patients who received a new fistula at the Royal Infirmary of Edinburgh.

Results

A total of 400 (300 retrospective and 100 prospective) patients were recruited for this study, with a mean age of 60.14 ± 15.9 years (development set) and 58 ± 15 years (validation set), respectively (P = 0.208). Study results showed that males were twice as likely to undergo fistula maturation as females, while patients with no evidence of peripheral vascular disease (PVD) were three times more likely to mature their fistula and a preoperative vein diameter > 2.5 mm resulted in a fivefold increase in fistula maturation as compared with a vein size of less than 2.5 mm. The model for fistula maturation had fair discrimination, as indicated by the area under the ROC curve (0.68), but good calibration as indicated by the Hosmer–Lemeshow test (P = 0.79). The area under the receiver operating curve for the validation model in the validation set was 0.59. Similarly, in the validation set, the Hosmer–Lemeshow statistic indicated an agreement between the observed and predicted probabilities of maturation (P > 0.05).

Conclusion

Gender, PVD, and vein size are independent predictors of AVF maturation. The clinical utility of these risk categories in the maturation of AVF requires further evaluation in longer follow-up.

Stent Grafts Can Convert Unusable Upper Arm Arteriovenous Fistulas into a Functioning Hemodialysis Access: A Retrospective Case Series

Introduction

Not all newly created arteriovenous fistulas (AVFs) successfully mature and develop into a functioning access for hemodialysis. Percutaneous transluminal angioplasty (PTA) and balloon-assisted maturation (BAM) have been utilized to either treat flow-limiting stenoses or to promote and accelerate maturation. We hypothesized that unusable upper arm AVFs can be rescued by conversion to a functional access using the percutaneous placement of a stent graft (SG).

Methods

Clinical data on 12 patients with an early non-usable upper arm AVF underwent percutaneous revision using SGs. There were six brachial–cephalic, three brachial–basilic, and three brachial–brachial vein transposition AVFs.

Results

All patients had either at least two or more stenoses (>2 cm) within the fistula conduit, or a long segment stenosis (>4 cm) in combination with shorter segment stenoses. Nine patients had failed PTA. Three patients had failed BAM at outside access centers. All patients were referred for failure to achieve access cannulation and concomitant hemodialysis through the AVF. SGs were placed retrograde toward the arterial anastomoses and ranged in diameter (6, 7, and 8 mm in four, seven, and one patients, respectively). The average length of the SG was 10 cm (range 5–15 cm). All SGs were post-balloon dilated at the time of placement. All AVFs were salvaged, and patients were able to maintain functional use of their access with cannulation occurring through the SG. The primary patency rate at 6 and 12 months was 91% [95% confidence interval (CI), 56–98%] and 65% (95% CI, 32–87%), respectively (n = 11 and 5 at risk, respectively). The secondary patency rate at 6 and 12 months was 100 and 72% (95% CI, 46–93%), respectively (n = 11 and 7 at risk, respectively).

Conclusion

This report outlines a successful initial experience using SGs to rescue, preserve, and convert an unusable upper arm AVF into a functioning hemodialysis access.

Transjugular Access for Endovascular Treatment of Immature Autogenous Arteriovenous Fistulae

PURPOSE

To assess the feasibility and outcome of transjugular access for endovascular treatment of immature arteriovenous fistulae (AVFs).

MATERIALS AND METHODS

Between August 2013 and January 2016, 90 patients (mean age, 64.5 y ± 12.8) underwent endovascular treatment of immature AVFs via transjugular access. The mean age of fistulae was 3.3 months ± 1.8. Total procedure time and technical and clinical success rates of endovascular procedures were assessed. Primary and secondary patency rates were calculated according to the Kaplan-Meier method, and complications were assessed.

RESULTS

All patients had inflow lesions, among which 19 (21.1%) had occlusions. The juxtaanastomotic segment was the most common site (44.3%). Transjugular access was successful in 83 patients (92.2%), and 7 required additional standard or transarterial access. The mean procedure time was 36.5 minutes. Technical and clinical success rates were 98.9% and 90.5%, respectively. Mean primary and secondary patency durations were 14.3 months ± 1.7 and 31.0 months ± 0.7, respectively. Primary patency rates at 3, 6, and 12 months were 84.4%, 67.3%, and 48.8%, respectively. Secondary patency rates at 6 and 18 months were 98.6% and 95.5%, respectively. Venous rupture occurred as a result of balloon inflation in 9 patients (10%), and was managed by balloon tamponade. There were no complications related to transjugular access during a mean follow-up period of 12.6 months.

CONCLUSIONS

Transjugular access for angioplasty of immature AVFs is feasible and safe. Potential problems associated with access in the outflow vein could be avoided by transjugular access.

A modified nontransposed brachiobasilic arteriovenous fistula versus brachiocephalic arteriovenous fistula for maintenance hemodialysis access

OBJECTIVE

With the growing need for reliable and durable upper arm hemodialysis access, we sought to compare the performance of a novel modified nontransposed brachiobasilic arteriovenous fistula (mNT-BBAVF) with that of the more traditional brachiocephalic arteriovenous fistula (BCAVF).

METHODS

Briefly, to construct an mNT-BBAVF, an incision is made on the ulnar side of the elbow. The brachial artery and basilic vein are then isolated, and a side-to-side anastomosis is performed without transposition of the basilic vein. Next, the proximal basilic vein and the perforating veins within the surgical field are ligated. In this study, we retrospectively reviewed the medical records of all patients who underwent either an mNT-BBAVF or a BCAVF between January 2011 and October 2014 to compare 1-year primary unassisted patency, cumulative patency, and complications. We also examined hemodynamic parameters of vessels in each fistula type.

RESULTS

We identified a total of 84 patients: 45 had a BCAVF, and 39 had an mNT-BBAVF. The two groups were well matched for baseline characteristics. Maturation rates at 1 month were 97% for mNT-BBAVF and 96% for BCAVF. The 1-year primary unassisted patency was significantly higher in the mNT-BBAVF group than that in the BCAVF group (87% vs 67%; hazard ratio, 2.86; 95% confidence interval, 1.11-6.40; P = .03), although cumulative patency did not differ (90% vs 73%; hazard ratio, 2.80; 95% confidence interval, 0.98-6.96 ; P = .06). There were no differences in thrombosis, failure of maturation, bleeding, steal syndrome, arm swelling, aneurysm, and stenosis between the two groups during the 12-month study. Importantly, diameters and blood flow volumes of the proximal cephalic vein, distal cephalic vein, and distal basilic vein in patients who received an mNT-BBAVF increased significantly after 12 months. All three vessels met the Kidney Disease Outcomes Quality Initiative (KDOQI) criteria for fistula maturation and were available for dialysis cannulation, whereas only the proximal cephalic vein in the BCAVF group met the maturation criteria and could be used for cannulation.

CONCLUSIONS

mNT-BBAVF appeared to be an effective alternative to BCAVF for upper arm hemodialysis access.

Use of a proactive duplex ultrasound protocol for hemodialysis access

OBJECTIVE

Arteriovenous fistula (AVF) creation is the preferred approach for hemodialysis access; however, the maturation of AVFs is known to be poor. We established a proactive early duplex ultrasound (DUS) surveillance protocol for evaluating AVFs before attempted access. This study determined the effect of this protocol related to improving AVF maturation.

METHODS

From 2008 to 2013, 153 patients received new upper extremity AVFs and an early DUS surveillance protocol at a single academic institution. The protocol involved an early DUS evaluation before hemodialysis cannulation of the AVF at 4 to 8 weeks after AVF creation. A positive DUS result was identified as a peak systolic velocity of >375 cm/s or a >50% stenosis on gray scale imaging, along with decreased velocity in the outflow vein. Patients with positive DUS findings underwent prophylactic endovascular or open intervention to assist with AVF maturation. Nature of secondary interventions, as well as AVF patency and maturation, were assessed. Overall clinical outcomes and fistula patency were investigated.

RESULTS

During the study period, 183 upper extremity AVFs were created in 153 patients, including 82 radiocephalic, 63 brachiocephalic, and 38 brachiobasilic AVFs. A mortality rate of 43% (n = 66) was observed in a median follow-up period of 34.5 months (interquartile range, 19.6-46.9). A total of 164 early DUS were performed at a median of 6 weeks (interquartile range, 3.4-9.6 weeks) after the initial creation. Early DUS showed nine AVFs were occluded and were excluded from further analysis. Hemodynamically significant lesions were found in 62 AVFs (40%); however, only 17 (11%) were associated with an abnormal physical examination. Positive DUS finding prompted a secondary intervention in 81% of the patients. Among those with positive early DUS findings, AVF maturation was 70% in those undergoing a secondary intervention compared with 25% in those not undergoing a prophylactic intervention (P = .011). Primary-assisted patency for AVFs with early positive and negative DUS findings were 83% and 96% at 6 months, 64% and 89% at 1 year, and 52% and 82% at 2 years, respectively (P < .001).

CONCLUSIONS

Early DUS surveillance of AVFs before initial access is reasonable to identify problematic AVFs that may not be reliably detected on clinical examination. Although DUS criteria for AVFs have yet to be universally accepted, proactive early postoperative DUS interrogation assists in the early detection of dysfunctional AVFs and improvement of fistula maturation. Despite improved patency in those with positive DUS findings who undergo prophylactic secondary intervention, overall patency remains inferior to those without an abnormality detected on early DUS imaging.

Balloon-assisted maturation for arteriovenous fistula maturation failure: an early period experience

PURPOSE

Balloon-assisted maturation (BAM) is emerging as a salvage management for arteriovenous fistula maturation failure (AVF MF). However, BAM is a relatively new, yet controversial technique for AVF maturation. Therefore, we evaluated the effectiveness of BAM for AVF MF.

METHODS

Between January 2012 and December 2014, 249 AVFs were created. The total MF rate was 24.8%. But, only 110 AVFs were enrolled, including 74 brachiocephalic (BC) AVFs and 36 radiocephalic (RC) AVFs. The follow-up period was 12 months. Among those, there were 42 MFs (22 BC AVFs and 20 RC AVFs) and 68 maturation successes (MS) (52 BC AVFs and 16 RC AVFs). BAM was involved in MF group. We compared the clinical characteristics, AVF flows, and AVF flow ratios of MF and MS groups. Also, we evaluated the etiology, management, and result of MF.

RESULTS

There was no difference in clinical characteristics between MF and MS groups. In MF group, 39 balloon angioplasties (BAs) for 42 AVF MFs were performed. Number of BA was 1.45 ± 0.57 and duration of BA was 21.30 ± 21.24 weeks. BAM rate was 46.2%. For 1 year after AVF creation, AVF flows of MS group were significantly larger than those of MF group (P < 0.05) but there was no difference in AVF flow ratio between MF and MS groups (P > 0.05).

CONCLUSION

BA for AVF MF is a relatively applicable and effective modality. Although a large volume study is necessary, we suggest BAM is an effective salvage management for AVF MF.

Predicting Factors for Successful Maturation of Autogenous Haemodialysis Fistulas After Salvage Percutaneous Transluminal Angioplasty in Diabetic Nephropathy: A Study on Follow-Up Doppler Ultrasonography

BACKGROUND

Maturation failure of autogenous arteriovenous fistula (aAVF) has been increasing after surgical procedures and the salvage percutaneous transluminal angioplasty (sPTA) for immature aAVF has been identified as an effective treatment modality.

OBJECTIVES

The aim of this study was to identify factors predicting successful aAVF maturation and to determine positive technical aspects of sPTA.

PATIENTS AND METHODS

We retrospectively reviewed medical records and radiological images of 59 patients who had undergone sPTA for non-maturing aAVFs. We analysed images from pre-surgical mapping Doppler ultrasonography, angiography, and angioplasty and follow-up Doppler ultrasonography performed within two weeks after sPTA. We assessed the following factors, for their ability to predict successful aAVF maturation: 1) patient factors (age; sex; co-morbidities; and aAVF age, side and type); 2) vessel factors (cephalic vein diameter and depth, presence of accessory veins, and pre- and postoperative radial artery disease); 3) lesion factors (stenosis number, location and severity); and 4) technical factors (presence of residual stenosis and anatomic success ratio (ASR) on follow-up Doppler ultrasonography).

RESULTS

The technical and clinical success rates were both 94.9% (56/59); the mean ASR was 0.84. An ASR of ≥ 0.7 and no significant residual stenosis (< 30%) (both P < 0.001) on two-week follow-up Doppler ultrasonography predicted successful aAVF maturation.

CONCLUSION

For more precise prediction of successful aAVF maturation after sPTA, short-term follow-up Doppler ultrasonography (< 2 weeks) was useful. If the ASR was < 0.7 or if residual stenosis was ≥ 30%, immediate repeat sPTA is recommended.

The Impact of Vein Mechanical Compliance on Arteriovenous Fistula Outcomes

BACKGROUND

Arteriovenous fistulae (AVFs) are the preferred access for hemodialysis but suffer a high early failure rate. The aim of this study was to determine how venous distensibility, as measured in vitro, relates to early outcomes of AVF formed with the sampled vein.

METHODS

Ethical approval was obtained for all aspects of this study. During AVF formation a circumferential segment of the target vein was sampled. Mechanical stress testing of the venous segments was undertaken using a dynamic mechanical analyzer, with progressive stress loading at 2 N/min to a maximum of 10 N or until sample disruption. Stress-strain curves were obtained for vein samples and Young's modulus (YM) calculated. Duplex assessment of the fistulae was undertaken at 30 days.

RESULTS

Thirty patients consented to participate with 29 samples obtained for analysis. Statistical comparison of YM demonstrated no relationship with common cardiovascular risk factors or dialysis status. Subject age greater than 65 was the only patient factor which showed a significant difference in YM (P = 0.05). Furthermore, a negative correlation was confirmed between age and YM (Pearson's r = -0.465, P < 0.05). Nine of the 29 subjects suffered an early AVF failure. Mann-Whitney U testing for differences in distribution reported that YM was significantly higher in those fistulas which failed (P < 0.005).

CONCLUSIONS

Reduced venous compliance appears to result in higher failure rates of AVFs. With the advancement of clinical tools such as speckle tracing ultrasound identification of vessel compliance in vivo may produce valuable additional information for clinicians planning AVF surgery.

Three-dimensional MDCT angiography for the assessment of arteriovenous grafts and fistulas in hemodialysis access

Arteriovenous grafts and fistulas are placed for long-term hemodialysis access, and their associated complications can lead to considerable morbidity. Multi-detector computed tomography (MDCT) images provide accurate delineation of hemodialysis access anatomy and show potential complications. This review makes the reader more familiar with vascular access anatomy and configurations, describes the appearance of access complications encountered on MDCT, and discusses endovascular and surgical treatment options for complications, which should aid in post-treatment evaluation.

Accessory veins in nonmaturing autogenous arteriovenous fistulae: analysis of anatomic features and impact on fistula maturation

The appropriate management of nonmaturing arteriovenous (AV) fistulae continues to be a controversial issue. While coil embolization of accessory side-branch veins can be performed to encourage maturation of nonmaturing AV fistulae, the true efficacy and optimal patient population are not well understood. Fistulagrams performed on nonmaturing AV fistulae were retrospectively reviewed in 145 patients (86 males, median age 63 years) for the presence of accessory veins. Fistula and accessory vein measurements were obtained, as were rates of eventual fistula maturation after accessory vein coil embolization. Of 145 nonmaturing fistulae, 49 (34%) had a stenosis without any accessory veins, 76 (52%) had a stenosis and one or more accessory veins, and 20 (14%) had an accessory vein without concurrent stenosis. Eighteen AV fistulae had one or more accessory veins without coexisting stenosis. Nine fistulae had a caliber decrease immediately downstream from the accessory vein. Coil embolization of dominant accessory veins with a caliber decrease immediately downstream (n = 6) resulted in a 100% eventual fistula maturation rate versus 67% for fistulae without this configuration (n = 6, p = 0.15). Accessory vein size was not correlated with maturation rates (p = 0.51). The majority of nonmaturing fistulae with accessory veins had a coexisting stenosis. Higher maturation rates may result with selected anatomic parameters, although additional studies with more robust sample sizes are needed prior to definitive conclusions.

Effectiveness of collateral vein embolization for salvage of immature native arteriovenous fistulas

PURPOSE

To investigate the value of collateral vein embolization (CVE) as a salvage treatment for nonmaturing native arteriovenous fistulae (AVFs) in patients requiring hemodialysis.

MATERIALS AND METHODS

A total of 49 patients undergoing CVE (N = 65) for immature native AVFs at a single institution were reviewed. The study included 42 patients treated by 56 embolizations. Average fistula age at time of intervention was 18.2 weeks. Each patient underwent angiographic evaluation for fistula immaturity, with clinical success defined by initiation of single-session hemodialysis through the native fistula.

RESULTS

Fistula maturity was achieved in 32 of 42 patients (76.2%). No major complications occurred. Average time from CVE to fistula maturity was 38.4 days. Angioplasty done with CVE was found in a statistically higher percentage of patients with fistula success versus failure (31.3% vs 8.3%; P = .039). Radiocephalic fistulae were seen in a higher percentage of fistula failures compared with successes, but the results were not statistically significant (83.3% vs 59.4%; P = .054). Thirty-four patients underwent CVE without angioplasty, which resulted in successful fistula maturation in 22 cases (64.7%). Radiocephalic fistulae were again seen in a higher percentage of fistula failures compared with successes, but the findings did not meet statistical significance (81.8% vs 54.5%; P = .052).

CONCLUSIONS

Coil embolization of competing collateral vessels as a salvage treatment for nonfunctioning autologous AVFs is a viable treatment option in the majority of patients. Patients with radiocephalic fistulae may be at higher risk for primary fistula failure, but the present data are inconclusive.

Coil Embolization as a Treatment Alternative for Dialysis-Associated Steal Syndrome

Steal syndrome is a rare but serious complication of arteriovenous fistulas (AVF) created as well as the angioplasty technique used for its maturation and can have severe consequences if left untreated. Standard treatment options generally lead to loss of fistula access, although newer practices such as coil embolization are being utilized to conserve the AVF. Here we illustrate a case of a 65-year-old man with end-stage renal disease on dialysis, who had a Brescia-Cimino (radiocephalic) AV fistula created and subsequently underwent balloon-assisted maturation for an underdeveloped fistula. One month later, the patient presented with a cold thumb and index finger along with parasthesias in those digits and was treated with coil embolization of the distal radial artery while leaving the AVF functional. Steal syndrome and the novel treatment option of coil embolization are reviewed here.

Therapeutic strategies to combat neointimal hyperplasia in vascular grafts

Neointimal hyperplasia (NIH) in bypass conduits such as veins and prosthetic grafts is an important clinical entity that limits the long-term success of vascular interventions. Although the development of NIH in the conduits shares many of the same features of NIH that develops in native arteries after injury, vascular grafts are exposed to unique circumstances that predispose them to NIH, including surgical trauma related to vein handling, hemodynamic changes creating areas of low flow, and differences in biocompatibility between the conduit and the host environment. Multiple different approaches, including novel surgical techniques and targeted gene therapies, have been developed to target and prevent the causes of NIH. Recently, the PREVENT trials, the first molecular biology trials in vascular surgery aimed at preventing NIH, have failed to produce improved clinical outcomes, highlighting the incomplete knowledge of the pathways leading to NIH in vascular grafts. In this review, we aim to summarize the pathophysiologic pathways that underlie the formation of NIH in both vein and synthetic grafts and discuss current and potential mechanical and molecular approaches under investigation that may limit NIH in vascular grafts.

The history of interventional nephrology

Visionary nephrologists in the early 1960s invented the dialysis machine, constructed arteriovenous shunts and fistulas, and designed vascular and peritoneal catheters to provide their patients with long-term dialysis. As the number of dialysis patients grew, the construction and care of vascular access was abandoned by nephrologists to surgeons and radiologists. There was a decline in the number of fistulas and an increase in grafts in the United States. Vascular access was not the first priority for the nonnephrologists, and this set the stage for the emergence of diagnostic and interventional nephrologists. These self-taught nephrologists trained others, resulting in a critical mass of subspecialists who founded the Society of Diagnostic and Interventional Nephrology. This review traces the origin of this exciting field from its pioneers to the society as it exists today. The future of this society depends on academic nephrology fellowship programs fostering training and research in this field.