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TECHNICAL PAPERS: Fluids/Heat/Transport

A New Method for Evaluation of Cavitation Near Mechanical Heart Valves

[+] Author and Article Information
Peter Johansen

Bioengineering Department, Penn State University, University Park, PA 16802Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital Skejby Sygehus, 8200 Aarhus N., Denmark

Keefe B. Manning

Bioengineering Department, Penn State University, University Park, PA 16802

John M. Tarbell

Department of Biomedical Engineering, The City College of New York (CUNY), New York, NY 10031

Arnold A. Fontaine, Steven Deutsch

Applied Research Laboratory, Penn State University, University Park, PA 16802

Hans Nygaard

Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital Skejby Sygehus, 8200 Aarhus N., Denmark

J Biomech Eng 125(5), 663-670 (Oct 09, 2003) (8 pages) doi:10.1115/1.1613297 History: Received November 14, 2002; Revised April 17, 2003; Online October 09, 2003
Copyright © 2003 by ASME
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Figures

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The top three schematics of the investigated valves show areas (shaded) of highest probability to find cavitation. The transducer position is illustrated as the dark shaded rectangle on the atrial aspect with the wire leaving. Below the schematics are three photographs which visualizes the cavitation.
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The different dp/dt obtained for the different investigated valves. The mean dp/dt±standard deviation was 2926±1183,2286±824, and 2585±1296 mmHg/s for the Björk-Shiley, CarboMedics, and Medtronic Hall, respectively.
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Images acquired at different loading rates. The data are divided in three degrees of cavitation based on visual judgments and criteria. Only frames with visual cavitation are shown, except for the non-cavitation category. Each frame represents 1/3 msec. Successive frames are shown with time increasing downward. Contrast and brightness of the images have been adjusted to enhance details.
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The spectra calculated are the total energy spectrum, the deterministic energy spectrum calculated from the ensemble average signal, and the non-deterministic spectrum being the difference between the total and the deterministic energy spectrum. Legends Light gray: Total energy density spectrum; Dark gray: Deterministic energy density spectrum; Black: Non-deterministic energy density spectrum.
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The non-deterministic energy and dp/dt plotted as a function of the cavitation degree based on the visual criteria for the three valves investigated.
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The non-deterministic energy plotted as a function of dp/dt for the three valves. Björk-Shiley r2=0.74; CarboMedics r2=0.99: Medtronic Hall r2=0.56.
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The RMS value of the high-pass filtered pressure data is plotted as a function of non-deterministic energy for the three valves. The high-pass filter is designed based on a priori knowledge of the particular valve’s mechanical resonance characteristic. Björk-Shiley valve r2=0.99; CarboMedics valve r2=0.98; Medtronic Hall valve r2=0.88.

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