國家衛生研究院 NHRI:Item 3990099045/1479
English  |  正體中文  |  简体中文  |  全文笔数/总笔数 : 12145/12927 (94%)
造访人次 : 908131      在线人数 : 909
RC Version 6.0 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
搜寻范围 查询小技巧：
  • 您可在西文检索词汇前后加上"双引号"，以获取较精准的检索结果
  • 若欲以作者姓名搜寻，建议至进阶搜寻限定作者字段，可获得较完整数据
    •  进阶搜寻
    主页 ‧ 登入 ‧ 上传 ‧ 说明 ‧ 关于NHRI ‧ 管理 到手机版


    jsp.display-item.identifier=請使用永久網址來引用或連結此文件: http://ir.nhri.org.tw/handle/3990099045/1479


    题名: Bubble observation and transient pressure signals in mechanical heart valve cavitation study
    作者: Xu, LJ;Hock, YJ;Hwang, NHC
    贡献者: Division of Medical Engineering Research
    摘要: Background and aims of the study: Cavitation in the mechanical heart valve (MHV) was first detected in Edwards-Duromedics (ED) clinical explants. Early studies indicated that the pitted surface of the valve leaflet was due to cavitation phenomena occurring during valve closing. Cavitation is seen as the transient appearance of bubbles on the MHV surface on valve closure. The cavitation bubbles occur due to abrupt pressure changes in the vicinity of the valve on valve closing. Hence, analysis of the recorded field pressure can provide useful information relating to cavitation potential. In the present study, MHV cavitation potential was evaluated by counting bubble appearance probability and measuring bubble-size using an image-processing method. A simple and reliable technique using wavelet packet analysis (WPA) to evaluate cavitation potential was also investigated. Methods: A single-valve, pneumatic-driven burst tester system with adjustable pressure control unit, was used to simulate the closing process in the heart mitral valve at three driving pressures: 200, 500 and 1,000 mmHg, using three valve models. A triggering and imaging system was developed within the burst tester system to capture images of cavitation bubbles at predetermined time delays on valve closing. Transient pressure signals were recorded on both sides of the MHV occluder, using a high frequency piezoelectric pressure transducer and a physiological pressure transducer. The pictures recorded were analyzed using image processing software to determine bubble appearance probability and bubble size. WPA was applied to the transient closing pressure signals to evaluate cavitation potential. Results: Cavitation intensity index (Cii) and bubble size-based cavitation index (BS-Ci) were measured by analyzing images captured at different time delays on valve closing at different driving pressures. WPA was used to analyze transient pressure signals at the inflow side of the MHV occluder at valve closure to calculate the WPA-based cavitation index (WPA-Ci). The three methods showed a similar trend for cavitation potential in the valves tested. Conclusion: In the present study, two new approaches to evaluate MHV cavitation were investigated, namely WPA and BS-Ci. The results obtained produced a similar trend to that seen with an earlier method based on counting the probability that cavitation bubbles occur. As cavitation is primarily a function of the transient pressure within the vicinity of the closing valve occluder, the WPA method can be an effective method for future investigation of cavitation potential of mechanical heart valves.
    关键词: Cardiac & Cardiovascular Systems
    日期: 2003-03
    關聯: Journal of Heart Valve Disease. 2003 Mar;12(2):235-244.
    Link to: http://www.ncbi.nlm.nih.gov/pubmed/12701797
    Cited Times(WOS): https://www.webofscience.com/wos/woscc/full-record/WOS:000181752900019
    Cited Times(Scopus): http://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=0037354216
    显示于类别:[黃煥常(2000-2008)] 會議論文/會議摘要

    文件中的档案:

    档案 描述 大小格式浏览次数
    ISI000181752900019.pdf446KbAdobe PDF649检视/开启


    在NHRI中所有的数据项都受到原著作权保护.

    TAIR相关文章

    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - 回馈