Scanning electron microscopic investigation of the afferent arteries of experimental femoral arteriovenous fistulae in rabbits.

Scanning electron microscopy of the intimal surface of anastomosed arteries of experimental femoral arteriovenous fistulae in rabbits was conducted to determine whether the muscular femoral artery differed from the elastic common carotid artery in its response to the hemodynamic stress of the arteriovenous shunt. Control femoral arteriotomies were performed in an additional five rabbits. The animals were sacrificed at varying intervals from 2 days to more than nine months postoperatively. Within two days postoperatively transverse and longitudinal tears involving the internal elastic lamina and also the endothelium appeared in the afferent artery as far proximal to the fistula as the lower abdominal aorta. Tears distal to the fistula were fewer and later in appearance. The tears healed rapidly. The response as demonstrated by this technique was similar to that of the common carotid artery of carotid-jugular fistulae except that tears appeared earlier postoperatively with longitudinal as well as transverse disposition. Similar tears were found in four of the five control arteriotomies in the vicinity of the suture or at the site of clamping. The experiments reveal the readiness with which hemodynamic stress induces intimal tears.