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Amplitude-weighted mean velocity: clinical utilization for quantitation of mitral regurgitation
M Enriquez-Sarano1, A M Kaneshige, A J Tajik
1Division 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.