Experimental microvascular autogenous vein grafts for arterial defects: II. A histopathologic study of the grafts

Twelve autogenous vein grafts, of average diameter 1.5 mm, which had been used to bridge defects in the contralateral femoral artery of adult rabbits by a minimally traumatic technique, were examined over a 12-week postoperative period. Each graft remained widely patent but showed fibroelastic intimal thickening with time. Further evidence of arterialisation was the development of a prominent subintimal layer of smooth muscle. Also noted was the presence of medial fibrosis, with both calcification and ossification. This latter is suggestive of damage due to disruption of the vasa vasorum. It would appear that arterialisation of microvascular vein grafts occurs independently of surgical trauma and is therefore difficult to avoid. However, these pathologic changes were not as severe, nor was there as much luminal narrowing, as at the previously described anastomotic sites. The most important cause of these changes appears to be arterial pressure.