Ultrastructural substrates of dystrophic calcification in porcine bioprosthetic valve failure.

摘要: Calcific degeneration is the main cause of porcine bioprosthetic valve failure. This dystrophic phenomenon has been studied by transmission electron microscopy in 26 explants; six normally processed unimplanted xenografts and a pig aortic from slaughterhouse served as controls. Loss endothelial lining proteoglycans were regular finding all commercially valves. In order to detect initial calcifications, we investigated particular areas apparently devoid mineralization at x-ray. Three ultramicroscopic features found: 1) intracytoplasmic interstitial calcospherulae 22 explants, 2) calcified collagen fibrils 15, 3) platelike calcium deposits upon amorphous material 3. X-ray diffraction energy-dispersive microanalysis identified Ca2+ crystals hydroxyapatite. From these findings there evidence that debris membrane fragments cusp cells represent one nuclei calcification.