Title

Mechanical heart valve (MHV) cavitation potential analyzed by transient pressure signals

Date of Award

1998

Availability

Article

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Biomedical Engineering

First Committee Member

Ned H. C. Hwang, Committee Chair

Abstract

A series of transient pressure signals (TPS) can be recorded using a miniature pressure transducer mounted near the tip of the inflow side of a mechanical heart valve (MHV) occluder during closure. A relationship appears to exist between the intensity and pattern of TPS and the cavitation potential of a MHV.In order to study the relationship between MHV cavitation and the TPS, we installed a MHV in a valve-testing chamber of a digitally controlled burst test loop. A CCD camera and a PC based image grabbing program were used to visualize cavitation bubbles appearing on or near the occluder surface. A special synchronization circuit was designed to record the TPS and the cavitation bubbles simultaneously. Two bileaflet MHVs were used as the models for this study. Cavitation bubbles were observed within 1 ms of the leaflet/housing impact.The valves were tested at various driving pressures between 100 and 1300 mmHg. MHV cavitation bubble intensities were qualitatively classified into three categories: (1) strong, (2) weak, and (3) none. Digital images of the MHV occluder inflow surface were recorded simultaneously with the TPS. TPS were studied by the time-frequency analysis method (spectrogram), and correlated to MHV cavitation potential. The intensity of the cavitation bubbles was found to be associated with burst test loop driving pressures during leaflet closure.

Keywords

Applied Mechanics; Engineering, Biomedical; Engineering, Electronics and Electrical; Health Sciences, Medicine and Surgery; Biophysics, General

Link to Full Text

http://access.library.miami.edu/login?url=http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:9934288