Patency, blood flow and histologic characteristics in end-to-end and end-to-side arteriovenous fistulas. Comparisons in an experimental model.

Experimental arteriovenous fistulas of end-to-end (ETE) and end-to-side (ETS) type were created with microsurgical technique in rabbits between the carotid artery and the facial vein. Blood pressure and blood flow through the fistulas were registered during the operation and the flow capacity (flow/BP) was calculated. Evaluation was made at 2 hours, 1 day, 1 month and 3 months. Immediately after completion of the anastomosis there was no statistically significant difference in blood flow capacity between the ETE and the ETS group. At 1 month the flow capacity had increased significantly in the ETS, but not in the ETE group. At 3 months 3/5 of the ETS anastomoses remained patent, but all the ETE types were occluded. Histologic findings included severe intimal thickening at the anastomotic level and on the venous side of the anastomosis at 1 and 3 months. The study indicated that late blood flow and patency may be greater in ETS than in ETE arteriovenous fistulas.