The effect of combined aspirin and dipyridamole therapy on thrombus formation in an arterial thrombogenic lesion in the dog.

We investigated the potential of aspirin and dipyridamole in combination to inhibit thrombus formation by comparing endarterectomized segments of 20 dog carotid arteries in animals treated with pre- and post-operative aspirin and dipyridamole to 20 arteries from untreated animals and 20 arteries from animals receiving intra-operative heparin. The temporal profile of thrombus formation was assessed by means of angiography, light microscopy, and scanning electron microscopy at time intervals ranging from 30 minutes to three months from the time of surgery. All of the aspirin-dipyridamole vessels remained patent and only one had significant gross thrombus formation. This contrasted to six occlusions and six significant gross thrombi in the control group and one occlusion and six significant gross thrombi in the heparin group. The combination of oral aspirin and dipyridamole minimizes thrombus formation in the highly thrombogenic lesion created by carotid endarterectomy in the dog.