Fluid dynamics of valve closure and sustained regurgitation in cardiac valve prostheses

It is believed that the fluid mechanical stresses associated with valve closure and sustained regurgitation are responsible for a significant portion of the blood damage observed with the use of mechanical cardiac valve replacements. The high velocity spikes and extreme pressure fluctuations associated with the impact of the occluder and the housing have been suspect in the initiation of cavitation, which can lead to increased hemolysis, excessive valve damage, and the formation of stable bubbles. These events have been photographed in vitro, and there is evidence of their occurrence in vivo. The fluid dynamic events at the instant of valve closure have not yet been captured experimentally. Two dimensional laser Doppler velocimetry was used to investigate the fluid dynamic aspects associated with valve closure and sustained regurgitation in vitro on artificial heart valves in the mitral position