Experimental and clinical evaluations of the optimum combination in size and type of prostheses on double valve replacement

The hemodynamics in combined aortic and mitral valve replacement was studied experimentally with Bjork-Shiley valve and silicon ball valve in circulatory mechanical simulator. According to the results, the hemodynamically best combination was a ball valve used as aortic valve and Bjork-Shiley valve as mitral valve, and the combination of Bjork-Shiley valve alone should be carefully employed for combined aortic and mitral valve replacement to a case with serious risk, because the perivalvular leakage particular to this valve is unexpectedly large. There is an optimum combination of Bjork-Shiley valves as to the size for minimizing the load to left ventricle. The optimum combinations were found to be 23A-29M, 21A-27M,19A-25M or 23M, and 17A-21M, respectively. Our clinical cases of combined aortic and mitral valve replacement were reviewed, referring to the above-described experimental results: the cases in which Starr-Edwards ball valves were used as aortic valve and Bjork-Shiley valves were used as mitral valve had much better prognoses than cases in which Bjork-Shiley valves were used in both aortic and mitral position. Even though Bjork-Shiley valves were used for both aortic and mitral valves, in the cases in which the optimum valve size combination shown above were chosen, prognoses were much better than cases in which the optimum combinations were not used. These clinical data were well coincident with our in vitro experimental results. Thus, it must be emphasized that the combinations of valves as to the type and the size should be carefully selected for improving the clinical results of combined aortic and mitral valve replacements.