Mechanism for cavitation phenomenon in mechanical heart valves |
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Authors: | Hwansung Lee Yoshiyuki Taenaka |
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Affiliation: | (1) Department of Artificial Organs, Research Institute, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, 565-8565 Osaka, Japan |
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Abstract: | Recently, cavitation on the surface of mechanical heart valve has been studied as a cause of fractures occurring in implanted
Mechanical Heart Valves (MHVs). It has been conceived that the MHVs mounted in an artificial heart close much faster than
in vivo sue, resulting in cavitation bubbles formation. In this study, six different kinds of monoleaflet and bileaflet valves
were mounted in the mitral position in an Electro-Hydraulic Total Artificial Heart (EHTAH), and we investigated the mechanisms
for MHV cavitation. The valve closing velocity and a high speed video camera were employed to investigate the mechanism for
MHV cavitation. The closing velocity of the bileaflet valves was slower than that of the monoleaflet valves. Cavitation bubbles
were concentrated on the edge of the valve stop and along the leaflet tip. It was established that squeeze flow holds the
key to MHV cavitation in our study. Cavitation intensity increased with an increase in the valve closing velocity and the
valve stop area. With regard to squeeze flow, the bileaflet valve with slow valve-closing velocity and small valve stop areas
is better able to prevent blood cell damage than the monoleaflet valves. |
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Keywords: | Artificial Heart Mechanical Heart Valve Cavitation Bubble Squeeze Flow |
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