Observation of cavitation bubbles in monoleaflet mechanical heart valves

Lee, Hwansung; Tsukiya, Tomonori; Homma, Akihiko; Kamimura, Tomohiko; Takewa, Yoshiaki; Tatsumi, Eisuke; Taenaka, Yoshiyuki; Takano, Hisateru; Kitamura, Soichiro

doi:10.1007/s10047-004-0258-8

Cited by 11 publications

(5 citation statements)

References 6 publications

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“…Thus, we have decided to use the Medtronic Hall valve in our electrohydraulic total artificial heart (EHTAH). However, in previous studies, we observed higher cavitation intensity in the Medtronic Hall valve than in other MHVs (3,4).…”

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confidence: 61%

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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contrasting

confidence: 61%

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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“…We recorded the cavitation images on the valve stop only. However, the cavitation bubbles could be observed on the center hole, due to the venturi effect, and on the inner side of the valve surface, due to the water hammer effect (5). It was likely that the high‐frequency signal after the collapse of the cavitation bubbles was caused by the collapse of cavitation bubbles at one of these locations.…”

Section: Discussionmentioning

confidence: 99%

“…In our previous studies, we investigated MHV cavitation in an electro-hydraulic total artificial heart (EHTAH) (5)(6)(7). We reported that most of the cavitation bubbles were observed around the valve stop and were caused by the squeeze flow, and the formation of cavitation bubbles depended on the valveclosing velocity and valve leaflet geometry (5)(6)(7).…”

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confidence: 99%

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Characteristics of Mechanical Heart Valve Cavitation in a Pneumatic Ventricular Assist Device

Lee

Taenaka

2008

Artificial Organs

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In previous studies, we investigated the mechanism of mechanical heart valve (MHV) cavitation and cavitation intensity with a nonsynchronized experiment system. Our group is currently developing a pneumatic ventricular assist device (PVAD), and in this study we investigated MHV cavitation intensity in the PVAD using a synchronized analysis of the cavitation images and the acoustic signal of cavitation bubbles. A 23-mm Medtronic Hall valve with an opening angle of 70 degrees was mounted in the mitral position of the PVAD after removing the sewing ring. A function generator provided a square signal, which used the trigger signal of the electrocardiogram R wave (ECG-R) mode of the control-drive console for circulatory support. This square signal was delayed by a delay circuit and was then used as the trigger signal for a pressure sensor and a high-speed video camera. The data were stored using a digital oscilloscope at a 1-MHz sampling rate, and then the pressure signal was band-pass filtered between 35 and 200 kHz using a digital filter. The band-pass filtered root mean squared (RMS) pressure and cavitation cycle duration were used as an index of cavitation intensity. The cavitation bubbles were concentrated at the valve stop, and the cavitation cycle duration and RMS pressure increased as the heart rate and driving pressure increased. At the low valve-closing velocity, bubble cavitation was observed near the valve stop. However, at the fast valve-closing velocity, cloud cavitation was observed. A high-frequency signal wave was generated when the bubbles collapsed. The cavitation cycle duration and RMS pressure increased as the valve-closing velocity increased linearly.

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“…34 Because this occurs immediately before complete leaflet closure, many researchers believe it is the main cause of cavitation inception. [19][20][21][22][23] The squeeze flow velocity was studied experimentally or numerically by many investigators. From their results, the squeeze flow velocity varies widely from 1.6 to 60 m/s.…”

Section: Introductionmentioning

confidence: 99%

Cavitation Phenomena in Mechanical Heart Valves: Studied by Using a Physical Impinging Rod System

Chen

et al. 2010

Ann Biomed Eng

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When studying mechanical heart valve cavitation, a physical model allows direct flow field and pressure measurements that are difficult to perform with actual valves, as well as separate testing of water hammer and squeeze flow effects. Movable rods of 5 and 10 mm diameter impinged same-sized stationary rods to simulate squeeze flow. A 24 mm piston within a tube simulated water hammer. Adding a 5 mm stationary rod within the tube generated both effects simultaneously. Charged-coupled device (CCD) laser displacement sensors, strobe lighting technique, laser Doppler velocimetry (LDV), particle image velocimetry (PIV) and high fidelity piezoelectric pressure transducers measured impact velocities, cavitation images, squeeze flow velocities, vortices, and pressure changes at impact, respectively. The movable rods created cavitation at critical impact velocities of 1.6 and 1.2 m/s; squeeze flow velocities were 2.8 and 4.64 m/s. The isolated water hammer created cavitation at 1.3 m/s piston speed. The combined piston and stationary rod created cavitation at an impact speed of 0.9 m/s and squeeze flow of 3.2 m/s. These results show squeeze flow alone caused cavitation, notably at lower impact velocity as contact area increased. Water hammer alone also caused cavitation with faster displacement. Both effects together were additive. The pressure change at the vortex center was only 150 mmHg, which cannot generate the magnitude of pressure drop required for cavitation bubble formation. Cavitation occurred at 3-5 m/s squeeze flow, significantly different from the 14 m/s derived by Bernoulli's equation; the temporal acceleration of unsteady flow requires further study.

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Observation of cavitation bubbles in monoleaflet mechanical heart valves

Cited by 11 publications

References 6 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

Characteristics of Mechanical Heart Valve Cavitation in a Pneumatic Ventricular Assist Device

Cavitation Phenomena in Mechanical Heart Valves: Studied by Using a Physical Impinging Rod System

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