Homologous transplantation of the mitral valve: a review

Numerous experimental studies were conducted on homologous transplantation of the mitral valve either for mitral or tricuspid valve replacement in the early '60s. The first mitral homograft in humans was performed in 1965 by Senning. Since that time, there has been a limited number of implants mainly because of technical difficulties related to the insertion of the papillary muscles. Based on principles established for mitral valve repair, a reproducible method of homograft replacement of the mitral valve was described. Following validation in animals, the technique was applied in a series of 104 patients undergoing partial or complete mitral valve replacement. Significant improvements concerned: selection of indications and contraindications, staged approach according to the extent of the lesions leading either to partial or total replacement, systematic use of prosthetic ring annuloplasty, understanding of papillary muscle anatomy allowing a rationale for a reliable attachment method. In hospital mortality was 3.8%. At 8 years, the incidences of patients free from cardiac death and from all death were 90.6% and 82% respectively. Freedom from any cardiac event (death or reoperation) was 72% at 7 years. Similarly to the aortic homograft, mitral homograft durability was decreased in younger patients. Partial homograft replacementoffered satisfactory results particularly in the case of endocarditis and enhanced the possibilities of valve repair. The limitations of the technique are: the technical difficulty which does not permit a completely standardized operation, the risk of early valve dysfunction related to valve mismatch and the risk of late deterioration mainly leading to stenosis. Homologous transplantation of the mitral valve was also applied for tricuspid valve replacement in the case of infective endocarditis or for replacement of a degenerated bioprosthesis. Satisfactory results have been reported. However due to the lack of anatomical landmarks, the implantation procedure has remained technically challenging. Thus until further progress demonstrates a clear superiority of the mitral homograft, bioprosthesis remains the gold standard for replacing the mitral or the tricuspid valve with a biological substitute.