Quantification of Acute Aortic Regurgitation by Color Doppler Flow in an Experimental Animal Model

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Abstract
Color Doppler flow studies were performed on ten anesthetized open-chest dogs. Acute aortic regurgitation was created in the dogs by a special valve-spreading catheter. The magnitude of valvular regurgitation was determined by aortic electromagnetic flow recordings of regurgitant fraction. Arbitrarily-designated grades of aortic regurgitation: mild (4%-10%), moderate (11%-30%), and severe ( greater than 30%) were assigned on the basis of electromagnetic flow. We attempted to obtain studies of varying degrees of AR in each animal. Mean regurgitant fraction for the three grades were 6.8 +/- 0.6% (n = 11), 22.0 +/- 2.4% (n = 7), and 40.4 +/- 2.5 (n = 20), respectively (each P less than 0.05). By color Doppler flow assessment, the ratio of regurgitant jet height to the left ventricular dimension at the junction of the left ventricular outflow tract and the aortic annulus (JH/LVOH) was measured in each study. AR was classified by Doppler as grade I (mild), 1%-24%; II (moderate), 25%-64%; and III (severe), greater than or equal to 65% jet height/left ventricular outflow tract height. Color Doppler flow correlated well with flowmeter assessment of regurgitant fraction. Color Doppler flow tests had a calculated sensitivity of 88%, specificity of 83%, and predictive value of 85% for significant (moderate + severe) aortic regurgitation. Our data support the concept that this method of color Doppler flow assessment provides a quantitative noninvasive evaluation of aortic regurgitation.