[Stenoses of arterioles and small intramural arteries of human hearts. A quantitative study (author's transl)].

Postmortem coronary angiographies with a pressure of 100 mm Hg were performed on 50 human hearts with various degrees of coronary arteriosclerosis. The frequency and degree of narrowing of arterioles and small intramural arteries up to diameters of 400 mu were investigated by giant sections through the whole myocardium. The frequency of stenosing intimal lesions depended on the diameter of the arteries. Mostly (1.8%) small arteries with a diameter between 100 and 200 mu were affected. As a rule the degree of narrowing was unimportant. Only in 23% it surmounted 20%, in nearly 5% it exceeded 30% and only in 0.5% the level of 50% was surmounted. In the different layers of the left ventricular myocardium and of the ventricular septum no significant differences in the frequency of stenosing intimal lesions could be found. But in the right ventricular wall an evidently inferior frequency was determined. There was a significant increase of stenosing lesions with age but not with increasing heart weight. As a rule we observed an inversed correlation between the degree of coronary arteriosclerosis and the frequency of stenosing lesions of arterioles and small intramural arteries. Perhaps a severe coronary atherosclerosis protects the small intramural arteries against intimal lesions. We conclude from our results that only very seldom a stenosis of small intramural arteries and arterioles causes ischemic myocardial lesions.