Amplitude-weighted mean velocity: clinical utilization for quantitation of mitral regurgitation

Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905.

OBJECTIVES. The purpose of this study was to determine the clinical usefulness of the amplitude-weighted mean velocity method for quantitation of mitral regurgitation. BACKGROUND. Amplitude-weighted mean velocity is a nonvolumetric method for calculating the mitral regurgitant fraction. Its previous validation at one center mandated an independent assessment of its usefulness and limitations. METHODS. In 56 patients with and 16 patients without mitral regurgitation, the regurgitant fraction was measured simultaneously by amplitude-weighted mean velocity, quantitative Doppler study and quantitative two-dimensional echocardiography. In 16 patients, multiple gain settings were used to determine the influence of this variable on amplitude-weighted mean velocity. RESULTS. In patients without regurgitation, amplitude-weighted mean velocity showed more scattering of regurgitant fraction (-18% to 23%) than Doppler (p = 0.016) or two-dimensional echocardiography (p = 0.022). The absolute value of regurgitant fraction was (mean +/- SD) 8 +/- 6%, 4 +/- 2% and 4 +/- 3%, respectively (p = NS). With increasing gain, the amplitude-weighted mean velocity mitral and aortic integrals increased, but the calculated regurgitant fraction remained unchanged. In patients with mitral regurgitation, significant correlation was found between amplitude-weighted mean velocity and Doppler study (r = 0.79, p = 0.0001) and between amplitude-weighted mean velocity and two-dimensional echocardiography (r = 0.76, p = 0.0001) for calculated regurgitant fraction, but the standard error of the estimate (12%) was large. CONCLUSIONS. The amplitude-weighted mean velocity-calculated regurgitant fraction is gain independent, whereas the aortic and mitral integrals are gain dependent. Compared with Doppler and two-dimensional echocardiography, it shows more scattering of values in patients without regurgitation, but the methods correlate significantly in patients with mitral regurgitation. Amplitude-weighted mean velocity can be used as a simple adjunctive tool for comprehensive, noninvasive quantitation of mitral regurgitation.

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