title: Biological tissue in heart valve replacement.
mesh_terms: D000328:Adult; D001021:Aortic Valve / Q000601:surgery; D006351:Heart Valves / Q000637:transplantation*; D006801:Humans; D008875:Middle Aged; D011664:Pulmonary Valve / Q000601:surgery; D014184:Transplantation, Homologous