[The heart in the elderly. Light and electron microscopy findings].

No specific morphological substrate has yet been found which could explain the reduced adaptability of the heart in old age. A review is given of the most striking changes which have been observed in the myocardium of elderly humans and animals, as revealed by light and electron microscopy. Heart muscle cells: In the myocytes of aged animals an increase in fat droplets and glycogen was observed, but there was a reduction of endoplasmic reticulum. Basophilic degeneration, which is a frequent alteration of myocardial cells in old people, is based on the storage of a glucose polymer. The age-related increase of lipofuscin particles in myocytes is well known. In the course of life they change their structure from a fine granular type in children to a coarse granular and vacuolated type in the aged. The importance of this wear and tear pigment for myocardial function is not known, which is also true for the altered lipid composition of the cellular membrane of myocytes in the hearts of the elderly. A reduction of the mitochondrial to myofibrillar ratio, which was found in the left ventricular myocardium of old old rats, may affect the adaptability of the heart, and changes in the ratio of myosin isoenzymes are suggested to be of importance in reduced contractility. Studies on the mitochondria in the aged myocardium revealed different results concerning size and numbers.(ABSTRACT TRUNCATED AT 250 WORDS)