Design Considerations for the Omniscience Pivoting Disc Cardiac Valve Prosthesis

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Abstract
Parametric studies are conducted in an effort to determine the optimum curvature and eccentricity for concave-convex pivoting disc prosthetic heart valves. Steady-state pressure measurements with prototype valves and laser-Doppler anemometer measurements of the velocity field with a two-dimensional model are presented. These results suggest that an optimum curvature exists and that the minimum eccentricity that promotes full opening should be used. Estimates of the shear stress distribution in the wake of the valve are computed. The maximum shear stress for both the major and minor outflow areas appear to be: 1) fairly evenly distributed, 2) well below the level for damage to the formed elements of blood as they pass through the valve, and 3) above the level required for the formation of a stable thrombus.