title: A comparative in vitro study of the closing characteristics of Björk-Shiley and Bicer-Val tilting disc mitral valve prostheses.
abstract: The replacement of mitral valves has become a relatively common procedure in cardiac surgery. Information concerning losses due to backflow through the valve may be used to assess and compare the physical characteristics of commercially available prostheses. A simple apparatus based on an artificial ventricle was used to measure closing volume, leakage volume, total volume, leakage rate and closing time on a beat by beat basis for Björk-Shiley and Bicer Val prosthetic mitral valves. The Björk-Shiley valve opened to 60 degrees and displayed a smaller closing volume than the Bicer Val, which opened to 75 degrees; and the Björk-Shiley displayed higher leakage than the Bicer Val, thus reducing its advantage in terms of closing volume. Overall, the Bicer-Val showed about 1 ml greater reflux per beat than the Björk-Shiley. Study of a Bicer-Val, modified to have an opening angle of 80 degrees, confirmed that valve closing volume was a function of opening angle.
mesh_terms: D002302:Cardiac Output; D002306:Cardiac Volume; D006350:Heart Valve Prosthesis; D008943:Mitral Valve / Q000502:physiology*; D008954:Models, Biological; D013599:Systole; D013997:Time Factors