Aging changes in the human aortic valve in relation to dystrophic calcification

Abstract

To elucidate the pathogenesis of aging changes and their relation to age associated calcification, a morphological study of 27 human aortic valves was carried out. Nine valves were obtained from immediate autopsies and 18 valves from routine autopsies done within four hours after death. Calcium deposition was present deep in the zona fibrosa along a zone of lipid accumulation. Fibrocytes in the zona fibrosa showed predominant age associated changes, i.e., a massive accumulation of residual bodies in the cytoplasm probably derived from autophagic vacuoles. Light microscopic lipid accumulation corresponded with both intracellular accumulation of electron dense spherules and membranous vesicles derived from degenerate fibrocytes. Calcium deposition in various stages, including needle shaped hydroxyapatite crystals, was seen in close association with these cellular degradation products rather than collagen or elastic fibers. Dystrophic calcification in the aortic valve appears to result from cellular aging and death followed by petrification of cellular degradation products, which may progress to calcific aortic stenosis.