ANTI-THROMBOTIC THERAPY FOR VASCULAR PROSTHESIS - AN EXPERIMENTAL-MODEL TESTING PLATELET INHIBITORY DRUGS

Abstract

Dacron vascular grafts are widely used, but they are thrombogenic and rapid blood flow maintains patency. When blood flow is suboptimal, antithrombotic therapy may prevent early occlusion. The effect of 3 platelet inhibitory drugs: acetylsalicylic acid (ASA), dipyridamole (DPM) sulfinpyrazone (SPZ) and a combination of ASA plus DPM on platelet adherence to woven Dacron in an artificial circulation was studied. Heparinized blood from 18 volunteers was divided equally for test and control circuits, and to the test each drug was added in therapeutic concentration. The experiment was repeated ex vivo, using blood donated by 6 volunteers after each had taken, separately, for 1 wk: no drug; ASA, 300 mg 3 times a day; DPM, 100 mg 4 times a day; SPZ, 200 mg 4 times a day, and ASA, 300 mg, plus DPM, 75 mg, combined, 3 times a day. Platelet count, adhesion and aggregation were measured during the 60 min perfusion, and scanning electron microscopy of the graft''s luminal surface was performed. ASA was the most effective single agent, significantly impairing platelet function and reducing consumption of platelets by the graft. DPM reduced platelet adherence only in the ex vivo experiment, and its addition to ASA imparted no further influence. Sulpinpyrazone had little effect in either experiment. Antithrombotic therapy with ASA and DPM requires clinical evaluation.