Doppler Quantitation of Aortic Regurgitation
July 1, 2000 3 minutes read
Doppler Quantitation of Aortic Regurgitation
abstract & Commentary
Synopsis: Jet width by color flow Doppler in the PLA view was the best predictor of aortic regurgitation by angiography, but better results were obtained when concordance with other measures was used.
Source: Evangelista A, et al. Am Heart J 2000;139: 773-781.
Despite the popularity of echo/doppler for the quantitation of aortic regurgitation, there is no agreement concerning the best method and the use of combining methods. Thus, Evangelista and associates used aortic root angiography in the 60° left anterior oblique (LAO) projection and the standard 1-4+ grading system as the gold standard to compare the various echo/Doppler methods in two phases. Phase I was an initial study of 60 patients evaluating the following color-flow Doppler variables: jet width at the annulus in the parasternal long axis (PLA) view; jet area at the valve in the parasternal short axis (PSA) view; and jet area in an apical 5 view. Each of these measures was also ratioed to left ventricular outflow tract diameter or area or the left ventricular area, respectively. Pulsed Doppler measures included: regurgitant flow by comparing aortic flow to pulmonic or mitral flow as appropriate. Continuous wave Doppler was used to obtain the aortic regurgitant velocity deceleration slope from the apical views. The second phase was a validation phase in 158 patients where the ranges determined in phase I to correspond to angiographic grades 1-4 were tested. The results of phase I showed that jet width correlated best with angiography (r = 0.91) and deceleration slope was worst (r = 0.74). In each case, ratios decreased the correlation. Intraobserver variability was least with jet width and apical jet area, and was the most with regurgitant fraction using the mitral flow and the PSA jet area. The phase II study included 90 patients with a central jet. Jet width was not obtainable in 2%, apical jet area in 5%, PSA jet area in 20%, regurgitant flow by pulmonary in 9%, regurgitant flow by mitral in 32%, and velocity slope in 25%. Agreement between echo/Doppler and angiography was within one grade for jet width in 85%, by apical jet area in 79%, and regurgitant flow by pulmonary in 75%. Eccentric jets decreased the agreement usually by underestimating severity. Also, concomitant valve disease also affected accuracy. Evaluating combinations of parameters showed that when jet width and apical jet area gave the same grade, agreement with angiography was 95%. If these two measures disagreed, using regurgitant fraction by pulmonary flow was helpful. If these three disagreed, PSA jet area resolved the issue. Overall if these three steps were used, agreement with angiography was 92%. Evangelista et al conclude that jet width by color flow Doppler in the PLA view is the best predictor of aortic regurgitation severity by angiography, but better results are obtained when a strategy of concordance with other measures is used, especially if the regurgitant jet is eccentric.
Comment by Michael H. Crawford, MD
The most interesting finding of this study is not that jet width was best, but that using ratios (i.e., jet width to left ventricular outflow tract height) made things worse. Also of interest was that regurgitant fraction using mitral flow and velocity slope were not only poor measures, but were unobtainable in 20-30% of patients. As expected, their results showed that eccentricity and other valve disease affect the accuracy of echo/Doppler measures. Jet width in the PLA view was the most accurate measure and the jet width cutoffs are fairly easy to remember: angio 1+ = < 4 mm; 2+ = 4-7 mm; 3+ = 7-10 mm; and 4+ = > 10 mm. Surprisingly, apical jet area was pretty good and had a low intraobserver variability. Since there was no perfect way to determine aortic regurgitation severity, Evangelista et al suggested a stepwise approach of agreement between methods to arrive at a final severity decision.
The major limitation of this study is the use of aortic root angiography as the gold standard and the fact that the Doppler measures are continuous variables and angiography is not. Also, Evangelista et al used the LAO projection, which some catheterization experts believe overestimates the severity of aortic regurgitation by angiography. They believe the right anterior oblique is more accurate. Although the true accuracy of each echo/Doppler measure may be in doubt, the relative value of each parameter is clearly provided by this study.
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