Current status of development and in vivo evaluation of the National Cardiovascular Center electrohydraulic total artificial heart system

Tatsumi, Eisuke; Taenaka, Yoshiyuki; Uesho, K.; Homma, Akihiko; Nishinaka, Tomohiro; Kakuta, Yukihide; Tsukiya, Tomonori; Takano, Hisateru; Masuzawa, Toru; Nakamura, Makoto; Koshiji, Kohji; Fukui, Yasuhiro; Tsukahara, Kappei; Tsuchimoto, K.; Wakui, H

doi:10.1007/bf02479967

Cited by 7 publications

(2 citation statements)

References 8 publications

(1 reference statement)

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“…An EHTAH with a stroke volume of 75 mL was connected to a Donovan mock circulatory loop tester (11). Under the pressure condition, the mean left atrium and mean aortic pressure were maintained at 13 and 100 mm Hg, respectively, and the mean right atrium and mean pulmonary artery pressure were maintained at 7 and 25 mm Hg, respectively.…”

Section: Methodsmentioning

confidence: 99%

Hydrodynamic Characteristics of Bileaflet Mechanical Heart Valves in an Artificial Heart: Cavitation and Closing Velocity

Lee¹,

Homma²,

Taenaka³

2007

Artificial Organs

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The aim of this study was to investigate the possibility of using the bileaflet valves in an electrohydraulic total artificial heart (EHTAH). Three kinds of bileaflet valves, namely the ATS valve (ATS Medical Inc., Minneapolis, MN, USA), the St. Jude valve (St. Jude Medical Inc., St. Paul, MN, USA), and the Sorin Bicarbon valve (Sorin Biomedica, Vercelli, Italy), were mounted in the mitral position on an inclined 45 degrees plane in an EHTAH. The pressure waves near the valve surface, the valve-closing velocity, and a high-speed camera were employed to investigate the mechanism for bileaflet valve cavitation. The cavitation bubbles in the bileaflet valves were concentrated along the leaflet tip. The cavitation intensity increased with an increase in the valve-closing velocity. It was established that squeeze flow holds the key to bileaflet valve cavitation. At lower heart rates, the delay time of the asynchronous closure motion between the two leaflets of the Sorin Bicarbon valve was greater than that of the other bileaflet valves. At higher heart rates, no significant difference was observed among the bileaflet valves.

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Section: Methodsmentioning

confidence: 99%

Hydrodynamic Characteristics of Bileaflet Mechanical Heart Valves in an Artificial Heart: Cavitation and Closing Velocity

Lee¹,

Homma²,

Taenaka³

2007

Artificial Organs

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“…Since 1987, our laboratory has been developing an electrohydraulic total artificial heart, and induced the mechanical heart valves (11), (12) . Hemolysis was very important point in an electrohydraulic total artificial heart, which occurred by cavitation as well as shear stresses.…”

Section: Inroductionmentioning

confidence: 99%

A Study on the Mechanism for Cavitation in the Mechanical Heart Valves with an Electrohydraulic Total Artificial Heart

Lee

Tsukiya

Homma

et al. 2004

JSME Int. J., Ser. C

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It has been conceived that the mechanical heart valves mounted in an artificial heart close much faster than in vivo use, resulting in cavitation bubbles formation. In this study, the mechanisms for cavitation in mechanical heart valves (MHVs) is investigated with monoleaflet and bileaflet valves in the mitral position with an electrohydraulic total artificial heart (EHTAH). The valve-closing velocity and pressure-drop through the valve were done, and a high-speed video camera was employed to investigate the mechanism for MHVs cavitation. The valve-closing velocity and pressure-drop of the bileaflet valves were less than that of the monoleaflet valves. Most of the cavitation bubbles in the monoleaflet valves were observed next to the edge of the valve stop and the inner side of the leaflet. With the bileaflet valves, cavitation bubbles were concentrated along the leaflet tip. Also, the number density of cavitation bubbles in the bileaflet valves was less than that of the monoleaflet valves. The number density of cavitation bubbles increased with an increase in the valve-closing velocity and the valve stop area. It is established that squeeze flow holds the key to cavitation in the mechanical heart valve. In a viewpoint of squeeze flow, the bileaflet valve with slow valveclosing velocity and small valve stop area, is safer to prevent of blood cell damage than the monoleaflet valves.Key Words: Mechanical Heart Valve, Cavitation Bubble, Closing Velocity, Squeeze Flow InroductionThe cavitation phenomenon in mechanical heart valves is well documented and has been visualized by stroboscopic photography(1) -(3) . Cavitation in a liquid flow field occurs at locations where the local pressure falls below the vapor pressure of the liquid, creating vaporous bubbles in the field (4) . The collapse of the cavitation bubbles generates a high-speed micro-jet and shock waves that may damage the valve surface and blood components.In general, the major causes of cavitation occurrence * Received 21st May, 2004 (No. 04-4120) * * Department of Artificial Organs, Research Institute, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan. E-mail: hslee@ri.ncvc.go.jp * * * Japan Association for the Advancement of Medical Equipment, 3-42-6 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan in a mechanical heart valve were as follows: venturi effect due to flow after valve closure at the narrow gap between leaflet and valve housing, water hammer effect due to the sudden stop of the MHV leaflets, and squeeze flow that can take place in the narrow gap between the closing leaflet and valve stop (5) . Bluestein et al. (6) reported that the caivtation bubbles cause to squeeze flow and its maximum velocity reach as high as 30 m/s. Lee et al.( 7) and Shu et al. (8) examined the cavitation threshold of dp/dt for different mechanical heart valves using stroboscopic photography. He et al. (3) investigated the mechanism of the formation of cavitation bubbles in cases involving Medtronic Hall valves; in that study, the average v...

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Observation of cavitation bubbles in monoleaflet mechanical heart valves

et al. 2004

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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.

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Current status of development and in vivo evaluation of the National Cardiovascular Center electrohydraulic total artificial heart system

Cited by 7 publications

References 8 publications

Hydrodynamic Characteristics of Bileaflet Mechanical Heart Valves in an Artificial Heart: Cavitation and Closing Velocity

Hydrodynamic Characteristics of Bileaflet Mechanical Heart Valves in an Artificial Heart: Cavitation and Closing Velocity

A Study on the Mechanism for Cavitation in the Mechanical Heart Valves with an Electrohydraulic Total Artificial Heart

Observation of cavitation bubbles in monoleaflet mechanical heart valves

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