Exertion and acute coronary artery injury.

Twelve cases of myocardial infarction as related to strenuous exertion are presented with the pathological findings in several of these cases. Three cases with coronary arteriography are also presented. The pathology of coronary arteriosclerotic plaques and the vulnerability to acute injury is reviewed and discussed. It is concluded that strenuous exertion can cause acute injury to coronary artery plaques due to the unusual stressful whip-like action to which coronary arteries are subject. These injuries may initiate as cracks in the plaques or subintimal hemorrhages and proceed to coronary occlusion and ultimate myocardial infarction. With this concept in mind we use the term of "crack in the plaque" (Black's Crack in the Plaque) to account for the sudden appearance of clinical coronary artery disease appearing during or shortly after exertion, or other stressful situations in patients without previous existing evidence of clinical coronary artery disease. This could also account for exacerbation of symptoms or death occurring after exertion in previously quiescent asymptomatic known coronary artery disease subjects. This concept may explain some of the puzzling features of coronary disease.