Quantification of aortic regurgitation with amplitude-weighted mean flow velocity from continuous wave Doppler spectra.

Aortic regurgitant fraction (RFao) was quantified by estimating the ratio of the forward blood flow through the aortic (Qao) and pulmonary (Qp) valve: RFao = 100(Qao - Qp)/Qao. Aortic and pulmonary flow were measured by the systolic time integrals of the amplitude-weighted mean velocity from continuous wave Doppler spectra recorded over the aortic and pulmonary valves. Thus, measurements are independent of the left and right ventricular outflow tract area. In 20 normal subjects, aortic regurgitant fraction ranged between -2.9% and +12.0% (mean +4.3%), the physiologic value being +2%. In 20 patients with pure aortic regurgitation, aortic regurgitant fraction obtained by Doppler spectra (y) was compared with that calculated from biplane left ventriculography and cardiac output determined with the Fick method (x). The correlation was r = 0.94, (SEE = 5.4%, which is 10.6% of the angiography-Fick mean value). The regression line was y = 0.87x + 6.6 (mean y = 51.2%, mean x = 51.1%). It is concluded that determination of aortic regurgitant fraction in pure aortic regurgitation by using the amplitude-weighted mean velocity from continuous wave Doppler spectra is accurate and allows easy noninvasive evaluation of the regurgitant fraction in routine clinical applications.