[Ultrastructural morphometric analysis of normally loaded human myocardial left ventricles from young and old patients (author's transl)].

An ultrastructural and morphometric analysis was performed on human myocardial left ventricle, obtained during surgical heart operations on normally loaded ventricles. The diagnoses of the patients were a) Persistant foramen ovale b) Atrial septal defect stage (I.-II) c) Mitral stenosis (stage III.-IV.). The median values of left ventricular pressure were not pathologically elevated. The patients were divided in 2 groups, the younger one ranging from 5-15 years, the older from 42-78 years. It was shown that the volume density of the interstitial tissue does not differ with the aging process. The number of the nuclei per test area of the heart muscle cells decreased within age (P less than 0.001). This finding suggests a decreasing process in the number of the heart muscle cells and an increase in size of the individual myocardial cell. Increase in the volume density of myofibrils was demonstrated at electron microscopical level with aging (P less than 0.02). The volume density of mitochondria is the same in both groups, whereas the volume density of the remaining cytoplasm (without myofibrils and mitochondria) decreases (P less than 0.05). The numberical density of the mitochondria increased in the older patient group (P less than 0.001).