Pathogenetic mechanism of stenosis in the intramural coronary artery.

In order to clarify the pathogenetic mechanism of stenosis in the intramural coronary branch, morphological changes were examined by postmortem coronary angiography and determination of the Coronary Stenosis Index of the Myocardium (CSIM) were made in hearts obtained by autopsy from 10 patients with hypertension, 15 with normotensive myocardial infarction, 25 with hypertensive myocardial infarction, 6 with mitral valvular disease, 7 with aortic stenosis and 14 control subjects. CSIM was significantly higher in patients with hypertension, infarction with hypertension and aortic stenosis than in other three groups, indicating higher incidence of stenosis in those with a left ventricular pressure load. There was no specific correlation between the degree of stenosis of the epicardial coronary artery and that of the intramural coronary branches supplied by the former in any groups examined. Major pathological changes of the intramural coronary branches were muscular hypertrophy of media and proliferation of internal elastic lamella, both observed with a high incidence in vessels with high CSIM values. These findings suggest that intramural pressure which exerted extravascular pressure played an important role in the pathogenetic mechanisms of stenotic changes in the intramural coronary branches.