Risk factors in infra-inguinal graft stenosis.

Intimal hyperplasia appears to be the universal vessel response to injury and is important in atherogenesis. In animal and in-vitro models, the initiation and promotion of this process has been associated with a number of risk factors found in the circulation. In man, approximately 25% of infrainguinal bypass grafts develop stenosis due to smooth muscle cell proliferation but it is not known if circulating risk factors influence this process. In these studies, circulating risk factors have been correlated with the development of hyperplastic stenoses in infrainguinal bypass grafts. Non-hyperplastic causes of stenosis have been excluded by peri-operative graft assessment. Duplex scanning and angiography were used to detect new stenoses occuring in the first postoperative year. Logistic regression shows association between graft stenoses and; continued cigarette smoking and elevated circulating levels of fibrinogen, Lp(a) and 5-HT. These associations are independent of graft material or whether grafts were studied prospectively or retrospectively. There were some differences in stenosis associated risk factors between vein and PTFE graft groups on univariate analysis. These results suggest that circulating risk factors do play a role in intimal hyperplasia and stenosis of human infrainguinal bypass grafts and support other work demonstrating a reduction in graft patency in association with similar abnormalities.