Small Arteriovenous Anastomosis In Fistula Creation: Establishing A Functional Vascular Access While Minimizing Steal Syndrome.

The size selection of the arteriovenous (AV) anastomosis in dialysis access creation requires a careful balance: the diameter must be large enough to accommodate sufficient flow for hemodialysis, but small enough to minimize the complication of steal syndrome. Steal syndrome affects up to 10% of patients after creation of dialysis access with sometimes devastating consequences. Conventional teaching recommends an 7-10 mm anastomosis. We sought to assess the efficacy of using a smaller (5-6 mm) anastomosis in new arteriovenous fistula (AVF) creation. We conducted a comparative retrospective analysis of patients who underwent fistula creation with a small versus regular size anastomosis at any upper extremity anatomic site between March 2019 and October 2020 at our institution. Anatomic sites included radiocephalic, brachiocephalic and brachiobasilic. All arteriovenous anastomoses were measured intra-operatively to be 5-6 mm in diameter for the small size groups and 8-10mm for the regular size group. Endpoints included steal syndrome, functional patency, primary patency and secondary patency. Out of 110 patients who underwent an AVF creation, 59.1% received a 5-6 mm anastomosis with a median follow-up time of 10±6 months. Patients' demographics and comorbidities were relatively similar between the two groups except for a higher rate of hyperlipidemia (55.4% vs. 28.9%, P=0.008) in the small size group. Patients in the small size group were more likely to undergo a radiocephalic fistula (40% vs. 4.5%, P<0.001) and to have a smaller mean vein diameter on preoperative duplex ultrasound (3.2±1mm vs. 3.9±1mm, P=0.0016) when compared to their regular size counterparts. During follow-up, none of the patients in the small group developed steal syndrome (0% vs. 9%, P=0.015). At 1 year, patients in the regular size group achieved higher rates of primary patency (67.9% vs. 46.9%, P=0.02); however, no difference was seen in 1-year primary-assisted patency (84.9% vs. 73.6%, P=0.3), secondary patency (89.6% vs. 79.5%, P=0.3) nor in functional patency (87.7% vs. 82.2%, P=0.64) between the small and regular size groups, respectively. The use of a 5-6 mm anastomosis in the creation of new arteriovenous fistulas of the upper extremities appears to be a technically safe option for dialysis access. Our experience suggests that smaller anastomosis still creates enough flow to maintain a functional AV access while minimizing the incidence of steal syndrome. Additionally, even with smaller vein sizes pre-operative, adequate dialysis access can be created via a small sized anastomosis, including distal arm access. Larger studies with longer follow-up are needed to evaluate long-term outcomes of small anastomosis fistulas.

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