Factors affecting the patency of arteriovenous fistulas for dialysis access

Abstract

The autologous arteriovenous fistula (AVF) is the accepted gold standard mode of repeated vascular access for hemodialysis in terms of access longevity, patient morbidity, and health care costs. This review assesses the current evidence supporting the role of various patient and surgeon factors on AVF patency. The literature was searched to identify the current evidence available for patient characteristics, methods of AVF planning, and anatomic factors that may affect patency outcomes after AVF formation. The use of adjuvant medications, surgical techniques, and policies for AVF maintenance are discussed in relation to AVF patency. Current literature supports patient factors, such as increasing age, presence of diabetes, smoking, peripheral vascular disease, predialysis hypotension, and vessel characteristics, as directly influencing AVF patency. Vessels of small caliber (<2 mm) or demonstrating reduced distensibility are unlikely to create a functional AVF. Current evidence does not support altered patency due to sex or raised body mass index (<35 kg/m(2)). Factors such as early referral for AVF, preoperative ultrasound vessel mapping, use of vascular staples, and intraoperative flow measurements affected AVF patency, but the use of medical adjuvant therapies did not. Programs of surveillance and various needling techniques to maintain patency are not supported by current evidence. Novel techniques of infrared radiotherapy and topical glyceryl trinitrate are possible future strategies to increase AVF patency rates. The limitations of available evidence include a lack of large, randomized controlled trials and meta-analysis data to support current practice. There is a complex interaction of factors that may affect the patency of an individual AVF. These need to be carefully considered when selecting surgical site or technique, adjuvant treatments, and follow-up protocols for AVFs.