Cardiovascular ochronosis

Abstract

A 64-year-old man with alkaptonuric ochronosis required aortic valve replacement for severe aortic stenosis and single-vessel aortocoronary artery bypass grafting for a subtotally occluded obtuse marginal branch of the circumflex coronary artery. Operative findings included ochronosis of a partly calcified aortic valve and the aortic intima. The aortic valve and a punch biopsy specimen of the ascending aorta were removed at surgery and were studied with transmission electron microscopy and light microscopy. The ultrastructural studies of the aortic valve revealed intracellular and extracellular deposits of ochronotic pigment. A portion of the extracellular ochronotic pigment represented degenerated cells. Large deposits of extracellular ochronotic pigment were associated with areas of valvular calcification. Electron microscopic study of the aorta disclosed ochronotic pigment in macrophages and smooth-muscle cells. Aggregates of extracellular ochronotic pigment in the intima and media appeared to be in locations of necrotic cells. Light microscopy also showed intracellular and extracellular deposits of ochronotic pigment. Our study suggests that extensive extracellular deposits of ochronotic pigment in the aortic valve may serve as a stimulus for dystrophic calcification. This may play a role in the development of aortic valve calcification and aortic stenosis associated with alkaptonuric ochronosis. To our knowledge, this is the first ultrastructural study of the aortic valve and aorta in alkaptonuric ochronosis.