Computer-assisted design of pivoting disc prosthetic mitral valves.

This paper describes the use of the new technique of computer testing to study the simulated performance of flat and curved pivoting disc prosthetic mitral valves. The design parameters considered are the radius of curvature of the occluder and the position of the pivot point. The performance criteria are the net stroke volume, the mean forward pressure difference, and the peak anterior velocity. The last of these criteria may be important in the prevention of small-orifice valve thrombosis. The best overall valve in the study has a radius of curvature equal to 1.5 times the diameter of the occluder and a pivot point located 0.39 mitral-ring diameters from the anterior border of the mitral anulus. The maximum angle of opening of this optimal valve is limited to about 70 degrees by fluid-mechanical forces. Nevertheless, the inclusion of a redundant stop in the mechanical design of the valve is indicated, since the computer experiments also reveal excessive opening and failure to close in valves with nearby parameter values. These studies illustrate the usefulness of computer testing in prosthetic valve design.