Partial replacement of mitral valve by homograft. An experimental study.

Satisfactory long-term clinical results with heart valves have renewed the interest in the use of mitral homografts, despite the technical difficulties with their surgical implantation. This report describes the behavior and viability of the partial mitral homograft in the ortotopic position in a chronic sheep model (n = 25). The 20 surviving animals were studied hemodynamically and were anesthetized and electively put to death 3, 6, 9, and 12 months after the operation. All specimens had a normal mitral valve without signs of infection or thrombosis. Light, scanning, and transmission electron microscopy showed the presence of viable endothelial cells from the recipient covering the graft, signs of reendothelialization, and organized dense collagen tissue. The structural integrity was more evident in the fresh mitral homografts. This method may provide consider improvement in the viability of the mitral homograft, and it could be a valid alternative for repair of mitral valve localized pathology.