Pathogenesis of aortoenteric fistula. An experimental study.

The pathogenesis of aortoenteric fistulas was studied in the experimental laboratory. In 23 dogs patch of woven dacron was interposed in the anterior wall of the infrarenal abdominal aorta. In two groups (I and II), the serosa denuded duodenal wall was sutured to an opening of the proximal anastomosis--creating a pseudoaneurysm--, with induction of staphylococcal bacteremia, without (group I) and with simultaneous administration of methicillin (group II) pre and postoperatively. In the remaining two groups (III and IV), the serosa stripped duodenal wall, was simply attached to overlay the intact proximal anastomosis, with induction of staphylococcal bacteremia, without methicillin in group II and with administration of methicillin without bacteremia in group IV. Aortoduodenal fistulas developed in 100% of animals in group I, 80% in group II and 14% in group III. No aortoduodenal fistula was observed in group IV. We conclude that mechanical factors have the decisive role for the formation of aortoenteric fistulas, especially the development of a false aneurysm, which subsequently ruptures into the duodenum or the bowel.