Quantitative Evaluation of Indicators of Cardiac Function in an Experimental Animal Model of Chronic Aortic Regurgitation
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Authors
Huskey, Kathryn D.
Issue Date
1998
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
One of the most difficult problems facing cardiologists today involves the therapy
of chronic aortic regurgitation, including the timing of aortic valve replacement. Aortic
regurgitation refers to a valvular heart disease in which a portion of the blood ejected into
the aorta during systole leaks back into the left ventricle during diastole, due to a faulty
aortic valve. Evaluation of aortic regurgitation currently focuses on indicators, such as
regurgitant fraction, which measure the severity of the regurgitation. This study was
designed to explore quantitatively the reliability of regurgitant fraction, and other
hemodynamic indicators, as quantitative indices of cardiac work.
Using a sheep model of chronic aortic regurgitation, several indicators were
measured. Regurgitant flow rates were recorded using electromagnetic flow meters,
cardiovascular pressures were obtained from high-fidelity catheters placed in the right
femoral artery and left ventricle, and continuous wave Doppler was used to determine
mean regurgitant jet velocity. These measurements allowed us to calculate left
ventricular stroke work and potential and kinetic energy expenditures due to
regurgitation.
A strong correlation existed between left ventricular stroke work and both kinetic
and potential energy (r2= 0.85, P = 0.001; r2 = 0.78, P <0.0001), pulse pressure (r2= 0.82,
p < 0.0001), left ventricular stroke volume (r2= 0.77, P <0.0001) and regurgitant volume
(~= 0.76, P <0.0001). The weakest correlation was found between left ventricular stroke
work and regurgitant fraction (r2 = 0.39, p = 0.002). Therefore, conventional evaluation
of aortic regurgitant severity does not include examination of the most important
determinants of left ventricular stroke work. Assessment of cardiac work in patients with
chronic aortic regurgitation would be improved by examining factors such as regurgitant,
volume and energy expenditure due to the regurgitation.
Description
vii, 23 p.
Citation
Publisher
Kalamazoo College
License
U.S. copyright laws protect this material. Commercial use or distribution of this material is not permitted without prior written permission of the copyright holder.