[Pathology of xenograft, allograft and autograft cardiac valves].
Histopathological changes in xenograft, allograft and autograft heart valves after implantation are discussed. Collagen is the most important structural element in all these valves. In xenograft, there is no synthetic or renewal mechanism to replace the collagen that is gradually broken down, either because of proteolysis or the mechanical stresses to which the cusps are subjected. Thus, the cumulative effect of this breakdown can lead to the formation of cuspal tears and perforations. Collagen in implanted xonografts tends to undergo a time-dependent process of focal calcification, which may result in stenosis and/or regurgitation and loss of mobility of the cusps. In cryopreserved allograft, the viability of donor cells is usually not sufficient to maintain the structure of the cusps. The durability of allograft is influenced by the degree of preservation of collagen and elastic fibers in the graft, attenuation of immunologic reaction and extent of fibrous sheathing. Pulmonary autografts keep their cellular population and structure after implantation, and may have growth potential. Progressive root dilatation is the most important cause of valvular failure after the Ross procedure.
Tamura
K
K
Division of Surgical Pathology, Nippon Medical School Hospital, Tokyo, Japan.
Ferrans
V J
VJ
D000818:Animals; D001705:Bioprosthesis; D006085:Graft Survival; D006351:Heart Valves / Q000473:pathology* / Q000637:transplantation*; D006801:Humans; D014182:Transplantation, Autologous; D014183:Transplantation, Heterologous; D014184:Transplantation, Homologous