Flow visualization in mechanical heart valves: Occluder rebound and cavitation potential

High density particle image velocimetry, with spatial resolution of O(1 mm) , was used to measure the effect of occluder rebound on the how field near a Bjork-Shiley Monostrut tilting-disk mitral valve. The ability to measure two velocity components over an entire plane simultaneously provides a very different insight into the flow compared to the more traditional point to point techniques (like Laser Doppler Velocimetry) that were utilized in pre vious investigations of the regurgitant flow. A picture of the effects of o ccluder rebound on the fluid how in the atrial chamber is presented. Specif ically, fluid velocities in excess of 1.5 m/s traveling away from the atria l side were detected 3 mm away from the valve seat in the local low pressur e region created by the occluder rebound on the major orifice side where ca vitation has been observed. This analysis is the first spatially detailed f low description of the effects of occluder rebound on the flow field past a tilting-disk mechanical heart valve and further reinforces the hypothesis that the rebound effect plays a significant role in the formation of cavita tion, which has been implicated in the hemolysis and wear associated with t ilting-disk valves in vivo. (C) 2000 Biomedical Engineering Society.