Accessory vein obliteration criteria for immature fistulae: a modest proposal for an old paradigm.

Venous stenosis and/or presence of accessory vein (av) are the two most common causes of early fistula failure. While treatment of stenosis is better defined, there are no clear criteria for obliteration of the av. Often, interventionalists rely on visual assessment of flow through the av and its diameter (significant if > 1/3 of the main fistula diameter) for intervention. The purpose of this study was to establish objective criteria for the management of av. Various computational fluid dynamics simulations were performed to analyze blood flow in the arteriovenous fistula (AVF). av of different diameters and angles was then added at various locations in the AVF and comparison of simulation results was undertaken. The computational model revealed that when the av was 33% of the diameter of the AVF, flow in av was only 7%. When diameter of the av was increased to 50% and 66% of the diameter of the AVF, flow through the av was 10% and 31% of the flow in main AVF, respectively. Location or angle of take-off of av did not alter flow. This report provides objective information regarding criteria for av obliteration. It needs to be further validated in randomized clinical trials.

Vascular access types in patients starting hemodialysis after failed kidney transplant: does close nephrology follow-up matter?

BACKGROUND: Native arteriovenous fistulae (AVFs) are preferred while central venous catheters (CVCs) are least suitable vascular access (VA) in patients requiring hemodialysis (HD). Unfortunately, around 80% of patients start HD with CVCs. Late referral to nephrologist is thought to be a factor responsible for this. We retrospectively analyzed the types of VA at HD initiation in renal transplant recipients followed by nephrologists with failed transplant. If early referral to nephrologist improves AVF use, these patients should have higher prevalence of AVF at HD initiation. METHODS: All patients who failed their kidney transplants from January 2002 to April 2013 were included in the study. Data regarding planning of VA by nephrologist, documented discussion about renal replacement therapy (RRT), estimated glomerular filtration rate (eGFR) at 6 months and last clinic visit before HD initiation, time of VA referral, and subsequent VA at dialysis initiation were gathered and analyzed. RESULTS: Eighty-three patients failed their transplants during study period. Data were inaccessible in six patients. Eleven patients started peritoneal dialysis (PD) while 66 started HD. Thirty-two had previous functioning VA while 34 needed VA. There were 11/34 patients (32%) with eGFR <15 mL/min at six months while 21/34 (61%) had eGFR <15 mL/min at last clinic visit before HD initiation. Only 11/34 (32%) had documented RRT discussion, 8/34 (24%) had VA referral, and 7/34 (21%) had vein mapping. A total of 30/34 (88.3%) started HD with CVC while 4/34 (11.3%) started HD with AVF (p<0.0001). CONCLUSIONS: Early referral to nephrologist by itself may not improve VA care amongst patient with end-stage renal disease.

Accessory Vein Obliteration for Early Fistula Failure: A Myth or Reality?

Early fistula failure (EFF) is a significant clinical problem causing lower rates of arteriovenous fistulae (AVFs) use in patients with ESRD on hemodialysis. The 2 main factors amenable to treatment and widely accepted to cause EFF are stenosis anywhere in the AVF circuit and/or presence of accessory vein (av). The role of stenotic lesions in causing EFF and their treatment options are relatively better defined with clear guidelines. On the other hand, assessing the significance of an av in causing EFF and the indications for its treatment seem to lack scientific recommendations based on robust clinical data. In this article, we review the pathophysiology of EFF as pertains to the presence of av's. Current recommendations for obliteration of av, the available techniques and the evidence to support current clinical practice are discussed. The possible cons of av obliteration are highlighted, while newer concepts and the need for future clinical trials are addressed.