Distribution and variation of thromboplastic and fibrinolytic activity of dacron aortic grafts.

The distribution and variation of thromboplastic and fibrinolytic activity were studied in various layers of polyester grafts in the dog aorta. One, four and 36 months after implantation, these grafts were removed together with segments of normal arteries and veins and dissected into three layers. The thromboplastic and plasminogen activator activities in these layers were then determined. It was found that in the early post-operative period, the thromboplastic activity in the Dacron graft neointima is very high, whereas that of the plasminogen activator is relatively low. With the passage of time the thromboplastic activity decreases and plasminogen activator activity increases. Similarly the thromboplastic activity in the neomedial and neoadventitial layers of the graft falls as time elapses after the implantation and the fibrinolytic activity gradually increases. These changes in thromboplastic and fibrinolytic activity increase the danger of graft thrombosis in the early post-operative period whereas in the later period they are favourable to maintenance of graft patency.