Pathophysiology of myocardial ischemia: importance of platelet-vessel wall interactions.

Clinical and experimental evidence for important interactions between platelets and vascular endothelium under conditions of myocardial ischemia is briefly summarized. The clinical evidence for a role of platelets in myocardial ischemia includes studies indicating alterations in platelet behavior and the therapeutic benefit of some antiplatelet drugs. Experimental evidence suggesting the importance of platelets in ischemia includes reductions in transmyocardial platelet number under these conditions, the cyclical reductions in coronary blood flow that result from intermittent intravascular platelet aggregation, and the relationship between induced platelet aggregation and cardiac arrhythmias. Evidence strongly suggesting the importance of platelet emboli and thromboxane generation as a major cause of reperfusion-induced ventricular arrhythmias is outlined.