Platelet Consumption by Arterial Prostheses: the Effects of Endothelialization and Pharmacologic Inhibition of Platelet Function

The thrombogenic mechanism of arterial grafts has been studied by determining the relative utilization of platelets, fibrinogen and plasminogen by human arterial prostheses, and by direct examination of arterial grafts in a baboon model. Forty-one survival and turnover measurements of (51)Crplatelets, (131)I-fibrinogen and (125)I-plasminogen in ten patients with aortofemoral knitted Dacron prostheses demonstrated platelet consumption after graft placement (platelet survival 4.2 days +/- 0.5 and turnover 68,000 plat/ul/day +/-10,000 compared with 8.2 days +/- 0.3 and 35,000 plat/ul/day +/- 5,000 respectively for control subjects with stable vascular disease, p < 0.01). In vitro platelet function test results were normal. Platelet consumption was interrupted by dipyridamole or a combination of dipyridamole and acetylsalicylic acid, and platelet survival normalized spontaneously during nine months postoperatively. No significantly increased consumption of fibrinogen or plasminogen was found in these patients with arterial grafts. Placement of impervious knitted Dacron velour aortic grafts in baboons reproduced platelet consumption that progressively normalized over six weeks postoperatively. Platelet survival measurements correlated directly with endothelial cell coverage of the graft luminal surface in these animals implying that endothelialization of the graft surface was also occurring postoperatively in patients.