On the Closing Sounds of a Mechanical Heart Valve

Wu, Changfu; Herman, Bruce A.; Retta, Stephen M.; Grossman, Laurence W.; Liu, Jia-Shing; Hwang, Ned H. C.

doi:10.1007/s10439-005-3237-1

Cited by 12 publications

(3 citation statements)

References 15 publications

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“…In a previous study by the authors, we investigated the valve closing sound in air, naturally without the presence of cavitation. 25 It was found that the frequency of the closing sound of a Bjö rk-Shiley Convexo-Concave valve can reach as high as 123 Ϯ 6 kHz, with 99% of the total sound energy being accounted for, which is close to the 100 kHz value observed by Herman et al 26 on a 27-mm Medtronic Hall tilting disc valve under noncavitating conditions in water. These results indicate that the mechanical closing sound of an MHV might contain frequencies higher than what were previously thought.…”

mentioning

confidence: 62%

A Novel Study of Mechanical Heart Valve Cavitation in a Pressurized Pulsatile Duplicator

Wu¹,

Retta²,

Robinson³

et al. 2009

ASAIO Journal

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Submission of data regarding the cavitation potential of a mechanical heart valve is recommended by the U.S. Food and Drug Administration in the device-review process. An acoustic method has long been proposed for cavitation detection. However, the question as to whether such a method can differentiate the cavitation noise from the mechanical closing sound has not been sufficiently addressed. In this study, cavitation near a Medtronic Hall tilting disc valve was investigated in a pressurized pulsatile duplicator. The purpose of pressurizing the testing chambers was to prevent cavitation under a normally cavitating loading condition to isolate the mechanical closing sound. By comparing the sound signals before and after pressurization, some noticeable differences were found between them. In the time domain, the intensity of the sound under a cavitating condition was much higher. In the frequency domain, the energy distribution of a sound signal was distinctively different depending on whether cavitation occurred or not. The valve closing sound had a large amount of energy in the low-frequency range (less than about 25 kHz). When cavitation took place, the sound energy shifted toward the high-frequency range (from 25 to 500 kHz).

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confidence: 62%

A Novel Study of Mechanical Heart Valve Cavitation in a Pressurized Pulsatile Duplicator

Wu¹,

Retta²,

Robinson³

et al. 2009

ASAIO Journal

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“…The electronic transducer can digitally record HS, laying the groundwork for subsequent processing and application of HS signal. Furthermore, HS can directly reflect the property of cardiac mechanical activity and provide useful information for early diagnosis of cardiac abnormalities [ 11 ].…”

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confidence: 99%

Deep Learning-Based Heart Sound Analysis for Left Ventricular Diastolic Dysfunction Diagnosis

et al. 2021

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The aggravation of left ventricular diastolic dysfunction (LVDD) could lead to ventricular remodeling, wall stiffness, reduced compliance, and progression to heart failure with a preserved ejection fraction. A non-invasive method based on convolutional neural networks (CNN) and heart sounds (HS) is presented for the early diagnosis of LVDD in this paper. A deep convolutional generative adversarial networks (DCGAN) model-based data augmentation (DA) method was proposed to expand a HS database of LVDD for model training. Firstly, the preprocessing of HS signals was performed using the improved wavelet denoising method. Secondly, the logistic regression based hidden semi-Markov model was utilized to segment HS signals, which were subsequently converted into spectrograms for DA using the short-time Fourier transform (STFT). Finally, the proposed method was compared with VGG-16, VGG-19, ResNet-18, ResNet-50, DenseNet-121, and AlexNet in terms of performance for LVDD diagnosis. The result shows that the proposed method has a reasonable performance with an accuracy of 0.987, a sensitivity of 0.986, and a specificity of 0.988, which proves the effectiveness of HS analysis for the early diagnosis of LVDD and demonstrates that the DCGAN-based DA method could effectively augment HS data.

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“…Other research groups have suggested that high-intensity transient pressure detected by ultrasonography was useful as an indication of cavitation intensity (8)(9)(10)(11)(12). The frequency of the pressure signal when cavitation bubbles collapse has been investigated using a pressure sensor or hydrophone, but the results varied widely (13)(14)(15). However, these experiments were performed under nonsynchronized conditions between the visual doi:10.1111/j.1525-1594.2008.00564.x observation of cavitation and the emitting of an acoustic signal.…”

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confidence: 99%

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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On the Closing Sounds of a Mechanical Heart Valve

Cited by 12 publications

References 15 publications

A Novel Study of Mechanical Heart Valve Cavitation in a Pressurized Pulsatile Duplicator

A Novel Study of Mechanical Heart Valve Cavitation in a Pressurized Pulsatile Duplicator

Deep Learning-Based Heart Sound Analysis for Left Ventricular Diastolic Dysfunction Diagnosis

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

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