QUANTIFICATION OF MITRAL REGURGITATION BY INTEGRATED DOPPLER BACKSCATTER POWER

Objectives. We attempted to determine whether continuous wave Doppler backscatter power could be used to quantify mitral regurgitation. Back ground. The power of a Doppler backscatter signal is proportional to t he number of scatterers insonated and, hence, to the moving volume of blood. The relative power of the continuous wave Doppler signals from mitral inflow and aortic outflow is therefore proportional to the rela tive volumes of blood in motion. Methods. Computer postprocessing was used to derive the relative power of the Doppler backscatter signal fr om the intensity of the pixels within the spectral display of anterogr ade aortic and mitral flow. The power ratio was used to calculate the regurgitant fraction in 20 patients (mean age 61.4 years) with mitral regurgitation. This Doppler regurgitant fraction was compared with tha t derived from angiographic left ventricular volume and thermodilution cardiac output. In addition, 12 normal control subjects were studied by the Doppler method. Results. Mean (+/-SD) catheterization regurgita nt fraction was 0.50 +/- 0.26, and mean Doppler regurgitant fraction w as 0.47 +/- 0.25 (r = 0.89). The limits of agreement between the two m ethods by Bland-Altman analysis were -0.21 to +0.27. In normal control subjects with an expected regurgitant fraction of close to zero, mean Doppler regurgitant fraction was 0.03 +/- 0.05. Conclusions. Doppler backscatter power from mitral and aortic inflow provides a new and acc urate method for quantifying mitral regurgitation.