[Calculation of the mitral valve area with the proximal convergent flow method with Doppler-color in patients with mitral stenosis].

In this study we evaluate prospectively a new color Doppler method for calculating the mitral valve area based on identifying a blue-red aliasing interfase proximal to the orifice, corresponding to the flow convergence region (FCR). This method can be used to calculate areas using the continuity equation. We studied 61 patients with stenosis. The mitral valve area was calculated using pressure half-time (PHT) Doppler method which were compared with values that obtained by the FCR method, according to the following formula. AVM (cm2) = 2 pi r2 x VN/Vmax; where "r" is the FCR radius measured from the orifice to the first color aliasing (blue-red interface); VN is Nyquist velocity and Vmax is the peak flow velocity by continuous wave Doppler. Twenty three patients had pure mitral stenosis and 38 double mitral lesion. Twenty patients were on sinus rhythm while 41 in atrial fibrillation. Calculated mitral valve area using the FCR method correlated well with mitral valve area determined by PHT method at a correlation coefficient of r = 0.96 (y = 0.097 x + 54.9, SEE = 0.10 cm2, p < 0.001). MVA by FCR ranged from 0.4 to 2.5 cm2 (mean = 1.19 cm2). MVA by PHT ranged from 0.42 to 2.48 cm2 (mean = 1.15 cm2). Color Doppler FCR method provides an accurate estimate of effective mitral valve area and may be useful as an alternative to the pressure half-time method. The calculated mitral valve area by the FCR method is not influenced by the presence of mitral regurgitation nor atrial fibrillation.