Quantitative ultrastructure of the myocardium in chronic aortic valve disease

Light and electron microscopic morphometry was carried out in tissue samples which were obtained from the left ventricular free wall in 29 patients with chronic aortic valve disease during open-heart surgery. 6 patients had aortic stenosis, 9 had aortic insufficiency and 14 had a mixed aortic valve lesion. Hemodynamics were studied before operation. Patients with mixed aortic valve disease had a higher left ventricular mass, a lower ejection fraction and mean circumferential fiber shortening rate than patients with aortic stenosis. Peak systolic wall stress was comparable between groups. The intracellular content of contractile material was lower and the sarcoplasmic volume was higher in mixed aortic valve disease than in aortic stenosis. Mitochondrial volume and interstitial fibrosis were not different between groups. Patients with aortic insufficiency showed no significant difference of parameters as compared to both other groups. We conclude that an intracellular deficiency of myofibrils causes lack of contractility in advanced hypertrophy due to mixed aortic valve disease.