A simple noninvasive measurement of stenotic mitral valve area: an alternative approach using M-mode and Doppler...

Doppler echocardiography is a widely used noninvasive technique to examine the mitral valve area (MVA) by obtaining mitral pressure half-time (PHT) and to assess the severity of the stenosis. However, several hemodynamic factors influence the PHT and may render the PHT data inaccurate in any measurement of MVA under certain conditions. Using a simple echo-Doppler (E-D) method, we assessed the MVA in a physiological equation. The mitral flow volume (MFV) is represented by MVA x transmitral mean flow velocity (mV) x diastolic filling time (DFT). Thus, the formula can be restated as MVA (cm2) = MFV (cm3)/mV (cm/sec) x DFT (sec). We measured MFV by M-mode, and mV and DFT by continuous wave Doppler echocardiography. This formula was tested in 43 patients with isolated mitral stenosis. MVA was obtained by the PHT and E-D methods, and the data obtained were validated against the results of cardiac catheterization. The results obtained using the E-D method showed much better correlation (r = 0.82) with those of catheterization than those with the PHT method (r = 0.52). The inter- and intraobserver variabilities were checked. The results obtained with the E-D method were found to be reproducible. To further validate the accuracy of the E-D method, MVA was measured by both methods at different R-R intervals after exercise and the results were compared. The MVA obtained by the PHT method showed marked variations; whereas, that obtained by the E-D method remained nearly constant. Similarly, in a patient with atrial fibrillation, the MVA assessed by the PHT method varied from beat to beat; whereas, the fluctuations in MVA were minimal using the E-D method. We concluded that the E-D method can be reliable and clinically easily applicable for the accurate assessment of MVA.