Age-related changes in elastic fibers of human heart.

The effects of age on the human heart elastic fibers were studied by light and electron microscopy. Studies were done on 15 hearts from male subjects 42 days to 87 years of age. Using specific staining procedures, the length of elastic fibers was determined by morphometry in the parenchyma of right and left ventricles. These studies suggest that the length of elastic fibers per unit heart volume is present early in life, possibly at birth, and thereafter remains constant until adulthood. Average fiber length increases significantly beyond the third decade of life which can be interpreted as a continuous formation of new fibers and a continuous apposition of elastic-type material to these fibers. Electron microscopy confirmed the presence of mature elastic fibers at birth, since they contained amorphous substance (elastin) surrounded by numerous microfibrils. In the adult hearts, the amount of amorphous substance has increased and the number of microfibrils has decreased. With advancing age the amorphous substance forms areas of rarefaction and the microfibrils have disappeared. Whether or not such morphometric modifications could influence the elastic properties of the ventricular myocardium requires further study.