Calculation of Mitral Valve Area in Mitral Stenosis Using the Proximal Isovelocity Surface Area Method. Comparison with Two-Dimensional Planimetry and Doppler Pressure Half Time Method.

Two-dimensional echocardiographic (2-D) planimetry and the Doppler pressure half-time (PHT) method have been used to estimate mitral valve area (MVA) in patients with mitral stenosis (MS). Recently, the proximal isovelocity surface area (PISA) method has been shown to be accurate for calculating MVA. The purpose of this study was to compare the PISA method with previous methods. Thirty patients with MS were studied; 17 had pure MS, 4 combined mild MR, 6 combined mild AR, and 3 combined MR and AR. Color Doppler flow mapping was performed at an aliasing (blue-red interface) velocity of 14 cm/sec using the zero-baseline shift. MVA was calculated as 2 x 3.14 x R2 x 14 x (theta/180) / PFV, where R is the distance from aliasing to orifice, 14 is the aliasing velocity, theta is the internal angle of the mitral valve, and PFV is the peak flow velocity at the mitral orifice. MVA was also calculated using the 2-D and PHT methods, and compared with the PISA method. MVA calculated using the PISA method correlated well with the 2-D (r=0.90, p < 0.01, SEE = 0.18 cm2) and PHT methods (r=0.82, p < 0.01, SEE = 0.24 cm2). Compared with the 2-D method, the standard error of the estimate of the PISA method was - 0.14+/-0.18 cm2 and the percent error was -10.4+/-18.9%. Compared with the PHT method, the standard error of the estimate of the PISA method was + 0.01+/-0.24 cm2 and the percent error was +3.4+/-34.6%. MVA calculated using the PISA method correlated well with the 2-D and PHT methods in patients with pure MS or with MS combined mild regurgitation. The PISA method may be useful for calculating MVA as an alternative method.