Consequences of intramyocardial arterial lesions in aortic valvular stenosis.

Proliferative lesions, which included collagen deposition, developed with age in intramyocardial arteries of 27 patients with aortic stenosis and matched controls. Those with the most extensive intramyocardial artery lesions developed massive subendocardial infarcts during surgery. Using histologic quantitation, the percent of intramyocardial arteries with lesions in a patient was correlated with decreases in the amount of muscle in arterioles between the subepicardial and subendocardial zones of the left ventricle. The mean decrease in arteriolar muscle was 43% in patients with aortic stenosis and 19% in controls. Blood pressures correlate with the amount of muscle in arterioles, so subendocardial perfusing pressures were presumably low in those with aortic stenosis. Patients with the greatest decrease in arteriolar muscle across the myocardium had the most impaired left ventricular function, i.e., highest end diastolic pressures, lowest ejection fractions, and lowest mean fiber shortening rates.