Steroids and immunosuppression. Effect on anastomotic intimal hyperplasia in femoral arterial dacron bypass grafts.

The effects of steroids and immunosuppression on 6-cm long bilateral femoral arterial Dacron bypass grafts were studied in 30 adult mongrel dogs. The dogs were serially placed into one of the following three groups: control, steroid, and immunosuppression. The control and steroid groups each had a 70% graft patency rate, whereas the immunosuppression group had a 100% eight-week graft patency rate. The results in the steroid group were not statistically different from the control group, whereas the results in the immunosuppression group were statistically different from the control. The decrease in internal diameter was secondary to a localized accumulation of tissue at the anastomotic site, which histologically appeared to be a hyperplastic intima morphologically different in each group. There is a substantial decrease in intimal hyperplasia at anastomotic sites and a higher graft patency rate in dogs treated with low-dose azathioprine as compared with control of steroid-treated animals. The mechanism seems to be a slower and more orderly intimalization rather than suppression of any specific intimal cellular elements.