Improved patency of prosthetic arteriovenous grafts with an acute anastomotic angle and flow diffuser

Conventional end-to-side anastomosis to establish venous outflow for prosthetic arteriovenous grafts often requires operative patch angioplasty within 1 year because of venous stenosis. Rather than conventional venous anastomosis, a modified end-to-side anastomosis at a 15-degree angle with a flow diffuser was constructed. Such diffusers allow decreased flow velocity and increased pressure, inhibiting boundary layer separation.

Ten brachial artery to axillary vein 6 mm straight se-polytetrafluoroethylene prosthetic arteriovenous grafts were created with this technique. Patients included 6 men and 4 women (mean age, 66.4 years; range, 54-80 years), all with renal failure and a history of diabetes. The degree of stenosis at the venous anastomosis was determined with duplex scanning at intervals of 6 months. Analysis of survival and cumulative primary patency estimates were determined with the Kaplan-Meier method.

Primary cumulative patency estimate of 100% for the modified group at 18 and 24 months was significantly greater than that for age-matched historic control fistulas with the conventional end-to-side anastomosis (n = 20): 18 months, 32%; 24 months, 32% (P <.05). Although venous stenosis could not be quantitated for thrombosed conventional fistulas, modified anastomoses had minimal stenosis at 24 months: mean area reduction, 30% (range, 20%-45%).

Incorporation of a flow diffuser and a 15-degree anastomotic angle significantly increases patency of prosthetic brachial artery to axillary vein grafts.