Ten different Types of mechanical and biological heart valves were compared by hydrodynamically. The resistance against forward flow, leakage after valvular closure and regurgitation during valvular closing were studied and discussed. Of ten prosthetic valves tested, the resistance and the leakage were observed to be minimum with the Hall-Kaster valve. The. S. J. M. valve chosed rapidly and was quick in response. The resistance of the biological valves was greater than that of the ball valve. However the biolgical valves showed very minimum leakage with quick respouse in valvular closing.
