Ultrastructure of cardiovascular lesions induced by hypervitaminosis D and its withdrawal

Aortic, coronary and cardiac lesions were induced in swine by a hypervitaminosis D3 diet Lipid-free intimal plaques overlying focally calcified medial or internal elastica occured in the thoracic aorta, pulmonary trunk and coronary artery of swine fed a basal ration supplemented with 250,000 IU of vitamin D3/kg of diet for an induction period of 4 months. Cartilage formation with minimal calcification was initiated in the aortic valve during this period. When such animals were subsequently fed only the basal ration free of excessive vitamin D3 for 3 months, intimal plaques regressed in the aorta and pulmonary trunk but progressed in the coronary artery. The calcific deposits in the medial elastica and internal elastica of all three arteries decreased in size. Atherosclerotic intimal thickening occurred in the main coronary arteries. The most severe lesion occupied 75 p.100 of the lumen area. Multiple intimal plaques were noted in the left atrium and aortic and mitral valves. The thickened intima at these coronary and cardiac sites contained calcified elastica and collagen fibers.