國家衛生研究院 NHRI:Item 3990099045/6846
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    题名: Statistical characteristics of mechanical heart valve cavitation in accelerated testing
    作者: Wu, C;Hwang, NHC;Lin, YKM
    贡献者: Division of Medical Engineering Research
    摘要: Background and aim of the study: Cavitation damage has been observed on mechanical heart valves (MHVs) undergoing accelerated testing. Cavitation itself can be modeled as a stochastic process, as it varies from beat to beat of the testing machine. This in-vitro study was undertaken to investigate the statistical characteristics of MHV cavitation. Methods: A 25-mm St. Jude Medical bileaflet MHV (SJM 25) was tested in an accelerated tester at various pulse rates, ranging from 300 to 1,000 bpm, with stepwise increments of 100 bpm. A miniature pressure transducer was placed near a leaflet tip on the inflow side of the valve, to monitor regional transient pressure fluctuations at instants of valve closure. The pressure trace associated with each beat was passed through a 70 kHz high-pass digital filter to extract the high-frequency oscillation (HFO) components resulting from the collapse of cavitation bubbles. Three intensity-related measures were calculated for each HFO burst: its time span; its local root-mean-square (LRMS) value; and the area enveloped by the absolute value of the HFO pressure trace and the time axis, referred to as cavitation impulse. These were treated as stochastic processes, of which the first-order probability density functions (PDFs) were estimated for each test rate. Results: Both the LRMS value and cavitation impulse were log-normal distributed, and the time span was normal distributed. These distribution laws were consistent at different test rates. Conclusion: The present investigation was directed at understanding MHV cavitation as a stochastic process. The results provide a basis for establishing further the statistical relationship between cavitation intensity and time-evolving cavitation damage on MHV surfaces. These data are required to assess and compare the performance of MHVs of different designs.
    日期: 2004-07
    關聯: Journal of Heart Valve Disease. 2004 Jul;13(4):659-666.
    Link to: http://www.ncbi.nlm.nih.gov/pubmed/15311875
    Cited Times(WOS): https://www.webofscience.com/wos/woscc/full-record/WOS:000222883200022
    Cited Times(Scopus): http://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=7044231252
    显示于类别:[黃煥常(2000-2008)] 期刊論文

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