[Ultrastructural changes in human myocardium with hypertrophy due to aortic valve disease and their relationship to left ventricular mass and ejection fraction (author's transl)].

Biopsies from hypertrophied left ventricles were obtained intraoperatively from patients undergoing valve replacement for aortic valve disease. The tissue was immediately fixed in glutaraldehyde and, after appropriate preparation, examined by light and electron microscopy. Morphologic characterization was carried out with respect to 1. qualitative alterations within myocytes, mostly degenerative, 2. measurement of cell diameter and the percentage of interstitial tissue volume within the total myocardium, 3. determination of volume densities of mitochondria, myofibrils, and cytoplasm in myocardial cells by morphometric techniques. Data from hypertrophied hearts were compared with those from normal hearts (control group). Analysis of morphologic and clinical data yielded the following results: 1. The increase in the clinically determined left ventricular muscle mass due to hypertrophy in aortic valve disease is caused by an increase in cellular diameter as well as an increase in interstitial tissue; 2. The morphologic correlate of the reduction of left ventricular function (EF) with increasing degrees of hypertrophy consists of an increase in interstitial tissue, i.e. fibrosis, and a marked relative loss of myofibrillar components from hypertrophied myocardial cells which is accompanied by an increase in cytoplasm-filled areas.