title: Observation of cavitation bubbles in monoleaflet mechanical heart valves.
abstract: Recently, cavitation on the surface of mechanical heart valves (MHVs) has been studied as a cause of fractures occurring in implanted MHVs. In the present study, we investigated the mechanism of MHV cavitation associated with the Björk-Shiley valve and the Medtronic Hall valve in an electrohydraulic total artificial heart (EHTAH). The valves were mounted in the mitral position in the EHTAH. The valve closing motion, pressure drop measurements, and cavitation capture were employed to investigate the mechanisms for cavitation in the MHV. There are no differences in valve closing velocity between the two valves, and its value ranged from 0.53 to 1.96 m/s. The magnitude of negative pressure increased with an increase in the heart rate, and the negative pressure in the Medtronic Hall valve was greater than that in the Björk-Shiley valve. Cavitation bubbles were concentrated at the edge of the valve stop; the major cause of these cavitation bubbles was determined to be the squeeze flow. The formation of cavitation bubbles depended on the valve closing velocity and the valve leaflet geometry. From the viewpoint of squeeze flow, the Björk-Shiley valve was less likely to cause blood cell damage than the Medtronic Hall valve in our EHTAH.
authors.affiliation: Department of Artificial Organs, Research Institute, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan. hslee@ri.ncvc.go.jp
authors.forename: Hwansung
authors.initials: H
authors.lastname: Lee
authors.forename: Tomonori
authors.initials: T
authors.lastname: Tsukiya
authors.forename: Akihiko
authors.initials: A
authors.lastname: Homma
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Kamimura
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Takewa
authors.forename: Eisuke
authors.initials: E
authors.lastname: Tatsumi
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Taenaka
authors.forename: Hisateru
authors.initials: H
authors.lastname: Takano
authors.forename: Soichiro
authors.initials: S
authors.lastname: Kitamura
mesh_terms: D019544:Equipment Failure Analysis; D006339:Heart Rate; D006350:Heart Valve Prosthesis / Q000009:adverse effects; D006801:Humans; D012039:Regional Blood Flow