Percutaneous management of perianastomotic stenosis in arteriovenous fistulae: Results of a prospective study

Comparison of percutaneous transluminal angioplasty and surgical revision after intraoperative dilatation with biliary tract probes for arteriovenous fistula stenosis at juxta-anastomosis

BACKGROUND

Percutaneous transluminal angioplasty (PTA) is widely used for stenosis of vascular access (VA) for hemodialysis. We aimed to evaluate the effectiveness of both PTA and surgical revision after intraoperative dilatation with biliary tract probes for juxta-anastomotic stenosis in autogenous radiocephalic arteriovenous fistulas (RCAVFs).

METHODS

We performed a retrospective analysis of PTA and surgical revision after intraoperative dilatation with biliary tract probes; these were the first interventions after RCAVF establishment in 112 patients with juxta-anastomotic stenosis. Anatomical (number of stenoses) and clinical variables (age and gender of the patient, time of hemodialysis, AVF age, presence of diabetes mellitus, and cause of end-stage renal disease) were reviewed. Technical success, clinical success, and post-intervention primary patency were evaluated.

RESULTS

Our study enrolled 35 patients in the PTA group and 77 patients in the surgical revision group. Clinical and technical success rates of both groups were 100%. There were no complications, such as bleeding or hematomas. Using the Kaplan-Meier method, the post-intervention primary patency rates at 3, 6, 9, 12, 18, and 24 months in the PTA group were 100%, 94.28%, 77.1%, 60%, 54.29%, and 45.71%, respectively, and those in the surgical revision group were 100%, 94.81%, 92.2%, 90.91%, 81.82%, and 76.62%, respectively. The post-intervention primary patency rates at 9-24 months in the surgical revision group were significantly higher than those in the PTA group (χ2 = 19.04, p < 0.0001).

CONCLUSION

The post-intervention long-term primary patency rate of surgical revision after intraoperative dilatation with biliary tract probes is higher than that of PTA for the first intervention of patients with juxta-anastomotic stenosis in RCAVFs. The surgical revision method is safe and effective, especially in hospitals that have not yet carried out PTA.

ACR Appropriateness Criteria® Dialysis Fistula Malfunction

The creation and maintenance of a dialysis access is vital for the reduction of morbidity, mortality, and cost of treatment for end stage renal disease patients. One's longevity on dialysis is directly dependent upon the quality of dialysis. This quality hinges on the integrity and reliability of the access to the patient's vascular system. All methods of dialysis access will eventually result in dialysis dysfunction and failure. Arteriovenous access dysfunction includes 3 distinct classes of events, namely thrombotic flow-related complications or dysfunction, nonthrombotic flow-related complications or dysfunction, and infectious complications. The restoration of any form of arteriovenous access dysfunction may be supported by diagnostic imaging, clinical consultation, percutaneous interventional procedures, surgical management, or a combination of these methods. This document provides a rigorous evaluation of how variants of each form of dysfunction may be appraised and approached systematically. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Outcome and Risk Factors of Restenosis Post Percutaneous Transluminal Angioplasty at Juxta-Anastomotic of Wrist Autogenous Radial-Cephalic Arteriovenous Fistulas: A Retrospective Cohort Study

BACKGROUND

This retrospective cohort study was to determine the factors related to restenosis post percutaneous transluminal angioplasty (PTA) at juxta-anastomotic of wrist radial-cephalic arteriovenous fistulas (RC-AVFs).

METHODS

We conducted a retrospective study of patients who underwent their first PTA for juxta-anastomotic stenosis at RC-AVF from January 1, 2016, to December 31, 2020. Patient and stenotic lesion characteristics and PTA procedure factors were included in the analysis. The primary and assisted primary patency post PTA of RC-AVFs were evaluated using the Kaplan-Meier analysis and log-rank test. A Cox proportional hazard model was used to identify factors associated with restenosis post PTA. The receiver operating characteristic (ROC) curve was employed to evaluate the predictive value of the risk factors for restenosis post PTA.

RESULTS

A total of 65 patients with a mean age of 59.09 ± 14.94 years were enrolled in the study. The mean RC-AVF age was 9.2 (4.9, 35.05) months, and the median time of intervention for stenosis was 10.8 (4.05, 41.35) months after AVF creation. The primary patency rates following the first PTA at 3, 6, 12, and 24 months were 93.9, 84.6, 63.1, and 55.4%, respectively. The assisted primary patency rates at 3, 6, 12, and 24 months were 95.4, 90.8, 87.7, and 84.6%, respectively. Cox proportional hazard regression analysis revealed the maximum balloon diameter >5 mm had a lower postoperative restenosis rate compared with the maximum balloon diameter ≤5 mm (hazard ratio = 0.422; 95% confidence interval [CI]: 0.201-0.884; P = 0.022). ROC curve analysis showed that the area under the curve of the maximum balloon diameter during PTA was 0.624 (95% CI, 0.486-0.762). The best critical value for the maximum balloon diameter was 6 mm, the sensitivity was 64.5%, and the specificity was 61.8%.

CONCLUSIONS

For the first PTA at juxta-anastomotic of wrist RC-AVFs without thrombosis and complete occlusion, the use of a balloon with a maximum diameter of ≤5 mm is a risk factor to the occurrence of restenosis within 12 months post PTA. The result may help in tailoring surveillance programs in patients with RC-AVF stenosis.

Swing segment stenosis: An unresolved challenge

The native arteriovenous fistula is considered the gold standard among all dialysis access options. Compared with alternatives such as grafts and central venous catheters, their use is associated with a lower risk of infective and thrombotic complications. This leads to better patient outcomes and reduced healthcare-associated costs. Recognizing these advantages, there is a global drive to increase the creation and use of such fistulas in hemodialysis patients. Swing segment stenosis is a common problem encountered with the creation and use of these fistulas that can hurt their maturation and longevity. A "swing segment" in an arteriovenous fistula is defined as a segment of vein that pursues a sharp, curved course. Due to poorly understood reasons, these swing segments tend to develop stenotic lesions that are extremely challenging to treat. This review aims to provide an overview of the pathophysiology, incidence, management, and prevention of these swing segment lesions. We believe that such knowledge will be useful for clinicians who deal with dialysis access creation and maintenance.

Efficacy of ultrasound-guided percutaneous transluminal angioplasty for arteriovenous fistula stenosis or occlusion at juxta-anastomosis: A 3-year follow-up cohort study

OBJECTIVE

Arteriovenous fistula (AVF) is the preferred access for hemodialysis. Percutaneous transluminal angioplasty (PTA) has become a choice for AVF stenosis, and ultrasound has been used in PTA more frequently.

METHODS

This single-center retrospective cohort study analyzed 129 patients who underwent PTA in the First Affiliated Hospital of Chongqing Medical University from January 2016 to December 2016. Angioplasty was performed using a noncompliant high-pressure balloon. The process was visualized by duplex scan. Our inclusion criteria were as follows: (1) stenoses or occlusions were located at the juxta-anastomosis site: the first 5 cm of the vein distal to the anastomosis; (2) stenosis was confirmed with the following conditions: (a) flow rates are <500 mL/min in the brachial artery and <200 mL/min in the fistula during dialysis, and (b) the stenosis diameter is <1.7 mm. We used the Kaplan-Meier curve to show the postintervention primary and secondary patency rates of patients with stenosis and occlusion.

RESULTS

Altogether, 129 patients with 76 males were analyzed. Moreover, 104 have AVFs on the left arm, and only one patient had an ulnar-basilic AVF, whereas others had a radial-cephalic AVF. The postintervention primary patency rates are better in occlusion cases (P < .05), whereas secondary patency rates have no difference. The postintervention primary patency rates are better in patients without diabetes mellitus (P < .05), whereas the secondary patency rates had no difference.

CONCLUSIONS

For juxta-anastomosis site stenosis or occlusion, PTA can be used to obtain satisfactory results.

Salvage of a Radiocephalic Arteriovenous Hemodialysis Fistula by Percutaneous Angioplasty to Increase Retrograde Flow from the Palmar Arch in Patients with an Occluded Radial Artery

This brief report presents 12 patients who underwent percutaneous transluminal angioplasty (PTA) to increase the retrograde blood flow from the palmar arch. All the patients had radiocephalic arteriovenous fistulas with occluded feeding arteries. The technical success rate was 100%. Three patients (25.0%) underwent surgical repair for restenosis, 2 patients (16.6%) underwent surgical repair for other reasons, 5 patients (41.8%) underwent repeated PTAs for restenosis, and 2 patients (16.6%) had no further treatment. The target lesion primary patency rates at 6, 12, 36, and 60 months were 90.9%, 54.5%, 36.4%, and 18.2%, respectively.

Percutaneous intervention for salvage of non-maturing arteriovenous fistulas: Which is the better approach, arterial or venous?

Objectives

To evaluate the efficacy and long-term patency of endovascular treatment for non-maturing native arteriovenous fistulas according to the approach route (arterial vs. venous).

Methods

Eighty-five patients underwent percutaneous transluminal angioplasty for non-maturing fistulas (63 radiocephalic and 22 brachiocephalic) between 2010 and 2019. Outcome variables such as procedural success, complications, and primary and secondary patency rates were analyzed from the patients’ demographic, angiographic, clinical, and hemodialysis records according to the approach route (venous access group, n = 53 and arterial access group, n = 32). The Kaplan-Meier method was used to analyze the patency rates.

Results

The mean duration from fistula creation to fistulography was 78.4±51.4 days (range, 1–180 days). The anatomical and clinical success rates were 98.8% and 83.5%, respectively. Lesions were most commonly located at the juxta-anastomosis (55.3%). Accessory cephalic veins were observed in 16 patients. The primary patency rates were 83.9%, 71.9%, and 66.3% and the secondary patency rates were 98.6%, 95.9%, and 94.2% at 3 months, 6 months, and 1 year, respectively. The degree of hypertension (P = 0.023), minimal preoperative vein size (P = 0.041), and increment in postoperative vein diameter were higher in the venous access group than in the arterial access group (P<0.01). The frequency of using cutting balloons (P = 0.026) and complication rate were higher in the arterial access group than in the venous access group (arterial access: 1 major, 8 minor; venous access: 4 minor; P = 0.015).

Conclusions

Aggressive evaluation and endovascular therapy can salvage most non-maturing fistulas. Transradial and distal radial approaches can be effective even for challenging lesions.

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.

A Novel Model of Balloon Angioplasty Injury in Rat Arteriovenous Fistula

BACKGROUND

There are very few animal models of balloon angioplasty injury in arteriovenous fistula (AVF), hindering insight into the pathophysiologic processes following angioplasty in AVF. The objective of the study was to develop and characterize a rat model of AVF angioplasty injury.

METHODS

Balloon angioplasty in 12- to 16-week-old Sprague-Dawley rats was performed at the arteriovenous anastomosis 14 days post-AVF creation with a 2F Fogarty balloon catheter. Morphometry and protein expression of endothelial nitric oxide synthase (eNOS), monocyte-chemoattractant protein-1 (MCP-1), alpha-smooth muscle actin (α-SMA), CD68 (macrophage marker), and collagen expression in AVFs with and without angioplasty were assessed.

RESULTS

In AVFs with angioplasty versus without angioplasty: (1) angioplasty increased AVF-vein and artery intimal hyperplasia, (2) angioplasty decreased eNOS protein expression in AVF-vein and artery at 21 days post-AVF creation and remained decreased in the AVF-vein angioplasty group at 35 days, (3) angioplasty increased AVF-vein and artery α-SMA expression within the intimal region at 35 days, (4) angioplasty increased the expression of AVF-vein MCP-1 at 21 days and CD68 at 21 and 35 days, and (5) angioplasty increased AVF-vein and artery collagen expression at 35 days.

CONCLUSION

Our findings describe a reproducible rat model to better understand the pathophysiologic mechanisms that ensue following AVF angioplasty.

Longitudinal computational fluid dynamics study of stenosis and aneurysmal degeneration of an aortorenal bypass

Saphenous vein graft (SVG) bypass placement is regarded as the optimal option for renal artery stenosis, which usually causes secondary hypertension and poor renal perfusion. Using computational fluid dynamics, this study aimed to investigate the underlying hemodynamic mechanism of the vein aneurysm and stenosis after aortorenal bypass surgery. Three-dimensional models were reconstructed based on computed tomographic angiography images of a 20-year-old female patient who suffered from uncontrollable hypertension using the image processing package Mimics (Materialise). The morphology and hemodynamic parameters in the healthy state, at initial presentation and at post-operative 9-month and 2-year follow-ups after surgery were analysed. The hemodynamic parameters became normal in the left and right renal arteries after bypass surgery. However, flow separation and stagnation occurred at the post-operative 9-month aorta-vein anastomosis, which caused asymmetrical flow and extremely high wall shear stress (WSS) and WSS gradients at the outflow vein tract, where the stenosis occurred 2 years later. In addition, the graft bending produced an asymmetrical flow pattern downstream. This research revealed that the abnormal hemodynamics, including flow separation and extremely high WSS values and gradients, caused by the retrograde flow of aortorenal bypass may be responsible for the SVG degeneration. In addition, flow asymmetry due to vessel bending is a potential risk factor for SVG aneurysm dilation.

Predictors of primary patency after percutaneous balloon angioplasty for stenosis of Brescia-Cimino hemodialysis arteriovenous fistula

OBJECTIVE

Percutaneous transluminal balloon angioplasty (PTA) is recommended as the first choice to treat stenosis of Brescia-Cimino arteriovenous fistulas (B-C AVFs). The ability to predict which B-C AVFs are at risk for recurrent stenosis post-PTA would allow closer monitoring of patients, and possibly result in surgical intervention rather than repeat PTA. The purpose of this study was to identify predictive factors of primary patency after PTA in B-C AVFs.

METHODS

Patients diagnosed with B-C AVF primary stenosis and treated by PTA between November 2013 and March 2018 were included in the study. Patient and stenotic lesion characteristics and PTA procedure factors were included in the analysis. The Kaplan-Meier method was used to analyze the primary patency rate. Cox proportional hazard regression analysis was used to identify factors predictive of decreased primary patency.

RESULTS

74 patients (35 males, 39 females) with a mean age of 61.68 ± 11.44 years (range, 36-84 years) were included in the study. The mean B-C AVF age was 16.34 ± 12.93 months (range, 2-84 months), and the median primary patency time was 7.79 ± 0.48 months. Cox proportional hazard regression analysis revealed stenosis location at the inflow artery [hazard ratio (HR)=3.83, 95% confidence interval (CI): 1.46-10.09] or anastomosis (HR = 1.90, 95% CI: 1.09-3.32), dilation >2 times during PTA (HR = 2.30, 95% CI: 1.22-4.34), and residual stenosis >30% (HR = 2.42, 95% CI: 1.26-4.63) were significantly associated with decreased patency.

CONCLUSION

In conclusion, the primary patency rate of PTA for B-C AVF dysfunction is reduced by dilation >2 times, residual stenosis >30%, and stenosis located at the inflow artery or anastomosis. These results may help in tailoring surveillance programs, multiple PTA, or a proximal re-anastomosis surgery in patients with AVF dysfunction.

ADVANCES IN KNOWLEDGE

A number of studies have been conducted to examine the predictors of primary patency after PTA, however, no definitive conclusions have been reached. Our study revealed that stenosis location at the inflow artery or anastomosis, dilation >2 times during PTA, and residual stenosis >30% were the predictors of primary patency after PTA, which may help in tailoring surveillance programs, multiple PTA, or a proximal re-anastomosis surgery in patients with arteriovenous fistulas dysfunction.

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.

Interwoven Nitinol Stents to Treat Radiocephalic Anastomotic Arteriovenous Fistula Stenosis

Purpose: To determine the clinical outcomes in hemodialysis patients after implantation of a Supera stent to treat juxta-anastomotic stenosis in radiocephalic arteriovenous fistulas (AVF). Materials and Methods: A single-center retrospective study was conducted of 42 consecutive patients (mean age 66.7 years, range 40–84; 26 men) who had a failing AVF due to juxta-anastomotic stenosis treated with the interwoven Supera stent between February 2014 and February 2018. A third of the patients had previous juxta-anastomotic intervention (either balloon angioplasty or open surgical revision). Results: The stent was inserted successfully in all patients. Overall mean follow-up was 12.2±8.2 months (range 3.8–38.3). Juxta-anastomotic segment primary patency estimates at 6 and 12 months were 92.5% and 59.8%, respectively, with assisted primary patency rates of 97.5% and 92.9%. Reintervention (elective drug-coated balloon angioplasty) occurred at a rate of 0.31 procedures/year. Two AVFs thrombosed during the 1-year follow-up and were revascularized using balloon angioplasty. Ultrasound measurements of brachial artery flow rates increased significantly from 543.5±96.72 mL/min (range 430–644) before intervention to 919.2±355.9 mL/min (range 200–1600) after intervention (p=0.047). Arterial pressures on hemodialysis improved from −142.3±24.9 mm Hg (range −100 to −180) to −123.4±21.9 mm Hg (range −100 to −184; p=0.051). No AVFs were lost or abandoned during the follow-up period. Conclusion: The interwoven Supera stent is a promising treatment for failing AVFs with juxta-anastomotic stenosis. Encouraging 1-year primary and assisted primary patency was demonstrated, with a low reintervention rate. This treatment facilitates long-term maintenance of AVF vascular accesses.

A one-sheath inverse method in vascular access intervention therapy for hemodialysis patients

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We describe a one-sheath inverse method in vascular access intervention therapy (VAIVT) for hemodialysis patients.

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It allows VAIVT to be performed using one sheath with one approach site in cases in which lesions are present on the upstream and downstream sides.

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Because vascular access location is usually superficial, the technique can be utilized with relative ease.

Introduction

Vascular access intervention therapy (VAIVT) is an essential interventional therapy in the field of hemodialysis therapy that allows for the long-term vascular access functionality to be maintained. The venous approach is often performed in VAIVT for arteriovenous fistula. When lesions are present on the upstream and downstream sides from the approach site, it is likely that two sheaths will be inserted from two facing punctures. However, we have adopted a one-sheath inverse method using a guidewire in such cases.

Case presentation

We herein describe the steps of the technique that we have performed and report the successful treatment of a 77-year-old woman who developed arteriovenous fistula failure.

Discussion

To the best of our knowledge, the concrete and detailed technique has not been reported in the English literature to date. The merit of the technique is that it allows VAIVT to be performed using one sheath with one approach site in cases in which lesions are present on the upstream and downstream sides from the approach site. The other benefits include pain reduction, a shortened operation time, and reduced costs. Because vascular access location is usually superficial, the technique can be utilized with relative ease.

Conclusion

A one-sheath inverse method is useful. We hope that the technique will be more widely recognized, allowing the technique to be applied to more cases.

Spanish Clinical Guidelines on Vascular Access for Haemodialysis

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

Restoration of Autologous Arteriovenous Fistula by Removal of the Occluded Short Venous Part and Venovenous End-To-End Anastomosis in a Hemodialysis Patient

Standard salvage procedures for occuluded autologous arteriovenous fistula (AVF) in a hemodialysis patient are endovascular and/or surgical therapy. When endovascular therapy and thrombectomy prove unsuccessful, it is most likely that creating a new AVF or arteriovenous graft will be considered. However, if the occuluded venous part is short, we have adopted an operative technique for repair of AVF by removal of the occluded short venous part and venovenous end-to-end anastomosis. To our knowledge, the efficacy and clinical course of restoration of AVF by the technique have not been reported to date. Here, we describe the technique and report the successful treatment of a hemodialysis patient who developed AVF occlusion.

Preoperative arterial microcalcification and clinical outcomes of arteriovenous fistulas for hemodialysis

BACKGROUND

Arteriovenous fistulas (AVFs) often fail to mature, but the mechanism of AVF nonmaturation is poorly understood. Arterial microcalcification is common in patients with chronic kidney disease (CKD) and may limit vascular dilatation, thereby contributing to early postoperative juxta-anastomotic AVF stenosis and impaired AVF maturation. This study evaluated whether preexisting arterial microcalcification adversely affects AVF outcomes.

STUDY DESIGN

Prospective study.

SETTING & PARTICIPANTS

127 patients with CKD undergoing AVF surgery at a large academic medical center.

PREDICTORS

Preexisting arterial microcalcification (≥1% of media area) assessed independently by von Kossa stains of arterial specimens obtained during AVF surgery and by preoperative ultrasound.

OUTCOMES

Juxta-anastomotic AVF stenosis (ascertained by ultrasound obtained 4-6 weeks postoperatively), AVF nonmaturation (inability to cannulate with 2 needles with dialysis blood flow ≥ 300mL/min for ≥6 sessions in 1 month within 6 months of AVF creation), and duration of primary unassisted AVF survival after successful use (time to first intervention).

RESULTS

Arterial microcalcification was present by histologic evaluation in 40% of patients undergoing AVF surgery. The frequency of a postoperative juxta-anastomotic AVF stenosis was similar in patients with or without preexisting arterial microcalcification (32% vs 42%; OR, 0.65; 95% CI, 0.28-1.52; P=0.3). AVF nonmaturation was observed in 29%, 33%, 33%, and 33% of patients with <1%, 1% to 4.9%, 5% to 9.9%, and ≥10% arterial microcalcification, respectively (P=0.9). Sonographic arterial microcalcification was found in 39% of patients and was associated with histologic calcification (P=0.001), but did not predict AVF nonmaturation. Finally, among AVFs that matured, unassisted AVF maturation (time to first intervention) was similar for patients with and without preexisting arterial microcalcification (HR, 0.64; 95% CI, 0.35-1.21; P=0.2).

LIMITATIONS

Single-center study.

CONCLUSIONS

Arterial microcalcification is common in patients with advanced CKD, but does not explain postoperative AVF stenosis, AVF nonmaturation, or AVF failure after successful cannulation.

Preemptive Open Surgical vs. Endovascular Repair for Juxta-Anastomotic Stenoses of Autogenous AV Fistulae: A Meta-Analysis

Purpose

There is controversy about the best mode of preemptive repair of juxta-anastomotic stenoses in radial-cephalic arteriovenous fistula (AVFs). The aim of the present review was to compare the outcome of surgical vs. endovascular repair of those AVF stenoses.

Methods

A systematic review and meta-analysis was performed for studies comparing the outcome of open surgical vs. endovascular preemptive repair of AVF stenoses located in the juxta-anastomotic region. A search was carried out in April 2015. The analyzed outcome measures were the primary patency at 12 and 18 months and the assisted primary patency at 24 months. In addition, assessment of the methodological quality of the included studies was carried out.

Results

Four non-randomized cohort studies (297 patients) were analyzed. A random effects model was used to pool the data. The pooled odds ratio (OR and 95% confidence intervals) for the primary patency at 12 and at 18 months was 0.42 (0.25-0.72) and 0.33 (0.2-0.56), respectively, showing statistically significant higher patency of the surgically repaired group. The pooled OR for the assisted primary patency at 24 months was 0.53 (0.28-0.98) also in favor of the surgically repaired group (p<0.04)

Conclusions

The available evidence, based on non-randomized cohort studies, suggests that surgery is the best way to treat ‘juxta-anastomotic’ stenotic lesions in distal radial-cephalic AVFs, although angioplasty remains a valuable but less durable option in this location of the stenosis.

Efficacy of percutaneous transluminal angioplasty on dysfunctional fistulae because of inflow stenosis

PURPOSE

Autogenous fistulas are the preferential vascular access for hemodialysis. The aim of this retrospective study was to determine the efficacy of angioplasty for dysfunctional fistulas because of inflow dysfunction. 


METHODS

We reviewed all the angiographic procedures performed on our institution between April 2007 and April 2009. Procedures performed in dysfunctional fistulas because of inflow stenoses were analyzed. Fistulas with stenoses out of these areas were excluded. The following data were collected: patient age and sex, fistula age at the time of intervention, location of fistula, number and location of stenosis, angiography referral criteria, clinical findings (presence or absence of thrills, bruits and pulsatility) and date of reintervention or failure. 


RESULTS

During the study period 215 fistulas were submitted to angiography of which, seventy-one presented inflow stenosis (33%). Mean follow-up was 21.72±9.26 months, and average age was 7.03 months. Two groups were considered: 31 fistulas comprising ≤6 months old, and 40 fistulas >6 months old. Primary patency rates±SE for older fistulas at 6, 12, 18 and 24 months, respectively, was 91.3%± 0.04%, 80.7%± 0.07%, 53.8% ±0.10% and 34.2±0.1% versus 91.7±0.08%, 57.1±0.14%, 23±0.14%, 11.4%± 0.1% for younger fistulas (P=0.04). Fistulas ≤6 months old and multiple stenosis were associated with a poorer primary patency rate (P=0.005).


CONCLUSIONS

Inflow stenosis is frequently associated with fistula dysfunction. In this study we only analyzed AVF with inflow stenosis and we have shown that angioplasty can have great patency results, particularly for single lesions in matured fistulas.

Restoration of autologous arteriovenous fistula by vascular stripping in a hemodialysis patient with venous neointimal hyperplasia

A significant number of arteriovenous fistulae fail because of venous neointimal hyperplasia-associated vascular blockage. We developed a surgical technique for repairing arteriovenous fistulae by surgically removing neointimal hyperplasia and vessel re-anastomosis. Here, we report the successful treatment of a case that developed arteriovenous fistula stenosis because of venous neointimal hyperplasia.

Hemodynamically significant arterial inflow stenosis in dysfunctional hemodialysis arteriovenous fistulae and grafts

PURPOSE

Hemodynamically significant arterial inflow stenosis in dysfunctional fistulae and grafts is poorly understood. No reliable clinical methods exist to detect arterial inflow stenosis. In this study, we assessed the accuracy of a novel screening method to detect arterial inflow stenosis in dysfunctional fistulae and grafts following successful juxta-anastomotic and venous outflow intervention.

METHODS

We prospectively evaluated all patients (N= 204) referred to our academic center for angiographic evaluation of a dysfunctional dialysis fistula/graft from May 1, 2006 to June 30, 2007. Following successful angioplasty/stenting of the venous outflow and juxta-anastomotic areas, patients were screened for arterial inflow stenosis. The screening method involved detection of 1) weak thrill, or sluggish blood flow on the post-intervention angiogram, 2) low mean arterial blood pressures in the dialysis access arm compared to the contralateral arm, and 3) inadequate blood flow at the first hemodialysis session post-intervention. If patients screened positive for any of these, they were further evaluated for arterial inflow stenosis.

RESULTS

Fifteen patients (15/204) were positive for arterial inflow stenosis on screening study. Eleven of those 15 had arterial stenosis on angiography, giving our screening method a positive predictive value of 73.3%. Eight patients were successfully treated by angioplasty/stenting. Two patients successfully underwent surgical intervention. Two year patency of revascularization was 91% (10/11).

CONCLUSIONS

Hemodynamically significant arterial inflow stenosis occurs and can be detected by simple clinical methods. Interventions for correction of the arterial inflow stenosis are successful.

Paclitaxel-coated balloon angioplasty vs. plain balloon dilation for the treatment of failing dialysis access: 6-month interim results from a prospective randomized controlled trial

PURPOSE

To report the 6-month results of a prospective randomized trial investigating angioplasty with paclitaxel-coated balloons (PCB) vs. plain balloon angioplasty (BA) for the treatment of failing native arteriovenous fistulae (AVF) or prosthetic arteriovenous grafts (AVG).

METHODS

The enrollment criteria for this non-inferiority hypothesis trial included clinical signs of failing dialysis access with angiographic documentation of a significant venous stenotic lesion in patients with AVF or AVG circuits. From March to December 2010, 40 patients (29 men; mean age 64.1 ± 14.3 years) were randomized to undergo either PCB dilation (n = 20) or standard BA (n = 20) of a stenosed venous outflow lesion. Regular angiographic follow-up was scheduled bimonthly. Study outcome measures included device success (<30% residual stenosis without postdilation), procedural success (<30% residual stenosis), and primary patency of the treated lesion (<50% angiographic restenosis and no need for any interim repeat procedures).

RESULTS

Baseline and procedural variables were comparably distributed between both groups. Device success was 9/20 (45%) for the PCB device vs. 20/20 (100%) for standard control BA (p<0.001). Procedural success was 100% in both groups after further high-pressure post-dilation as necessary. There were no major or minor complications in either group. At 6 months, cumulative target lesion primary patency was significantly higher after PCB application (70% in PCB group vs. 25% in BA group, p<0.001; HR 0.30, 95% CI 0.12 to 0.71, p<0.006).

CONCLUSION

PCB angioplasty improves patency after angioplasty of venous stenoses of failing vascular access used for dialysis.

Improved cumulative survival in fistulas requiring surgical interventions to promote fistula maturation compared with endovascular interventions

Due to high nonmaturation rates, arteriovenous fistulas (AVF) frequently require intervention(s) to promote maturation. Endovascular or surgical interventions are often undertaken to salvage nonmaturing AVFs. The objective of this study was to compare the impact of surgical versus endovascular interventions to promote AVF maturation on cumulative AVF survival. We evaluated 89 patients with new AVF placement from a Veterans Affairs population over a 5-year period. Of these, 46 (52%) required intervention(s) to achieve successful maturation for dialysis: 31 patients had surgical revisions and 15 patients had endovascular repairs. We compared cumulative survival between AVFs requiring no intervention, surgical revision, and endovascular intervention to promote AVF maturation. Cumulative survival was longer in AVFs receiving surgical intervention compared with angioplasty to promote AVF maturation (p = 0.05). One-year cumulative survival was 86% vs. 83% vs. 40% for no intervention vs. surgery vs. angioplasty, respectively. In AVFs that required interventions to promote maturation, AVFs with surgical intervention had longer cumulative survival compared with those AVFs with endovascular intervention. AVFs with surgical intervention to promote maturation had similar 1-year cumulative survival to those AVFs that did not require intervention to promote maturation.

Defining a significant stenosis in an autologous radio-cephalic arteriovenous fistula for hemodialysis

The current definition of a significant stenosis in an autologous arteriovenous fistula (aAVF), the percentage narrowing compared with the adjacent "normal" vessel, is inaccurate. We believe a significant stenosis in the aAVF is an absolute minimal luminal diameter determined by the requirements of the hemodialysis pump. To determine what absolute diameter constitutes a hemodynamically significant stenosis in a radio-cephalic autologous arteriovenous fistula (RC aAVF), the minimal luminal diameter of dysfunctional RC aAVF was compared to that of functional RC aAVF using grayscale and color ultrasound. There were 93 fistulas in study group and 77 in control group. The mean minimum luminal diameter in study group was significantly lower than in control group (2.19 vs. 4.71 mm, p 0.001). With a cutoff value of 2.7 mm, there was 90% sensitivity and 80% specificity in distinguishing functional fistula from dysfunctional fistula. The area under the receiver-operator curve was 90% (CI 84-94%), indicating that a 2.7 mm diameter is accurate in discriminating functional from dysfunctional fistulas. An absolute minimal luminal diameter of 2.7 mm, as determined with grayscale and color ultrasound, is a useful cutoff for defining significant stenosis in a RC aAVF.

Origin of neointimal cells in arteriovenous fistulae: bone marrow, artery, or the vein itself?

To elucidate the source of neointimal cells, experimental fistulas were created in Lewis wild-type (WT) and transgenic rats that constitutively expressed the green fluorescent protein (GFP) in all tissues. Arteriovenous fistula (AVFs) were created by anastomosing the left renal vein to the abdominal aorta. The contribution of bone marrow (BM)-derived cells to the AVF neointima was examined in lethally irradiated WT rats that had been rescued with GFP BM cells. Neointimal cells in these chimeric rats were mostly GFP negative indicating the non-BM origin of those cells. Then, the contribution of arterial cells to the AVF neointima was assessed in a fistula made with a GFP aorta that had been implanted orthotopically into a WT rat. Most of the neointimal cells were also GFP negative demonstrating that AVF neointimal cells are not derived from the feeding artery. Finally to study local resident cells contribution to the formation of neointimal lesions, a composite fistula was created by interposing a GFP vein between the renal vein and the aorta in a WT recipient rat. GFP neointimal cells were only found in the transplanted vein. This study suggests that neointimal cells originate from the local resident cells in the venous limb of the fistula.

Decreased cumulative access survival in arteriovenous fistulas requiring interventions to promote maturation

BACKGROUND AND OBJECTIVES

New arteriovenous fistulas (AVF) are frequently unsuitable for hemodialysis because of AVF nonmaturation. Aggressive endovascular or surgical interventions are often undertaken to salvage nonmaturing AVFs. The effect of early interventions to promote AVF maturation on subsequent long-term AVF outcomes is unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We evaluated 173 hemodialysis patients from two academic centers who received a new AVF. Of these, 96 (56%) required no further intervention, 54 (31%) required one intervention, and 23 (13%) required two or more interventions to achieve suitability for dialysis. We calculated AVF survival and frequency of postmaturation interventions in each group.

RESULTS

Cumulative AVF survival (access cannulation to permanent failure) in patients with two or more versus one versus zero interventions before maturation was 68% versus 78% versus 92% at 1 year, 57% versus 71% versus 85% at 2 years, and 42% versus 57% versus 75% at 3 years. Using Cox regression analysis with interventions before maturation, age, sex, race, diabetes, peripheral vascular disease, access site, and obesity in the model, intervention before maturation (two or more) was the only factor associated with cumulative AVF survival. The number of interventions required to maintain patency after maturation was 3.51 ± 2.20 versus 1.37 ± 0.31 versus 0.76 ± 0.10 per year in patients with two or more versus one versus zero interventions before maturation.

CONCLUSIONS

Compared with AVF that mature without interventions, AVF that require interventions have decreased cumulative survival and require more interventions to maintain their patency for hemodialysis.

Retrograde occlusive arteriography of hemodialysis access: failure to detect inflow lesions?

Once thought to be a minor player in hemodialysis (HD) access dysfunction relative to outflow stenosis, inflow stenosis has recently come to be viewed as a major cause of access failure. Indeed, recent literature has shown that up to 40% of all accesses referred for dysfunction have an inflow lesion. Imaging of the inflow segment has been traditionally performed by interventional nephrologists via retrograde occlusive arteriography (ROA). Recent advances in our understanding of ROA have cast the technique in a negative light, with the possibility of vascular complications and poor diagnostic yield coming to the fore. Using a prospectively collected, vascular access database, we identified 18 consecutive patients who received imaging of inflow lesions by ROA and direct arteriogram (DA). The mean percent luminal stenoses were found to be 59.89 ± 24 and 79.06 ± 17.8 (p = 0.009) for the ROA vs. DA groups, respectively. Using multiple regression analysis, DA was found to be associated with detecting higher degree of luminal stenosis (β = 19.17, 95% CI 6.28-32.05, p = 0.006). This small case series provides evidence on the theoretical concern that ROA does not adequately evaluate inflow lesions. We may conclude that by relying solely on ROA, interventional nephrologists may be failing to detect a subset of hemodynamically significant inflow lesions.

Juxta-Anastomotic Stenosis of Native Arteriovenous Fistulas: Surgical Treatment versus Percutaneous Transluminal Angioplasty

Purpose

Juxta-anastomotic stenosis (JAS) is a complication of arteriovenous fistulas (AVFs). Both surgical revision (SR) and percutaneous transluminal angioplasty (PTA) may correct JAS. In this study we compare the results for SR treatment versus PTA.

Methods

From January 2005 until December 2008, 66 PTA and 68 SR were performed in 43 and 57 uremic pts with JAS of the native AVF, respectively. Efficacy of SR and PTA was evaluated measuring brachial arterial flow (BAF) by CDU. The Kaplan-Meier table of primary and assisted primary patency was analyzed.

Results

PTA was attempted in 50 patients. PTA failed in 7 patients and they were switched to SR. In 43 pts, PTA produced a favorable effect, with a mean increase of 99 ± 70% (p<0.001) in blood flow. Restenosis occurred in 17 pts: 2 were treated by SR and 15 by PTA. Restenosis occurred again in 6/15 pts: after second restenosis, 5/6 pts received a third PTA with stenting, 1 patient underwent SR. The failure of access occurred after 12–17 months in 3 pts. In 57/57 JAS treated by SR, a new well-functioning fistula was created upstream of the stenosis, with a mean increase of 102 ± 71% in blood flow (p<0.001). Restenosis occurred in 15 pts: 9 were treated by SR and 6 by PTA. Access failure occurred after 3–36 months in 9 pts. The Kaplan-Meier table showed a better primary patency for SR (p<0.05) without difference in assisted primary patency.

Conclusions

SR showed a better primary patency then PTA, confirming the trend to stenosis relapse after PTA. So, as PTA does not exclude a later correction of the JAS, the similar assisted patency suggests to perform a PTA first, reserving SR for after its failure.

Arterial stent placement in arteriovenous dialysis access by interventional nephrologists

Arterial stenoses in patients with arteriovenous dialysis access can create a variety of problems including access dysfunction, thrombosis, and hand ischemia. While percutaneous balloon angioplasty is largely successful in the management of arterial stenoses, elastic recoil can present a real predicament to this treatment. In this report, we present two cases of arterial stenosis that demonstrated elastic recoil after angioplasty and required endovascular stent insertion. Both cases were treated successfully without any complications on an outpatient basis. This report describes arterial stent placement in patients with arteriovenous access and discusses anticoagulation considerations in such cases.