Value and limitations of Doppler pressure half-time in quantifying mitral stenosis: a comparison with micromanometer catheter recordings. The purpose of this study was to compare the Doppler and catheterization pressure half-time methods of estimating mitral valve area with valve areas obtained by the Gorlin equation in a group of patients with clinically significant mitral stenosis. Data were analyzed from 67 consecutive patients who were undergoing continuous-wave Doppler examination and catheterization with micromanometer catheters. Doppler pressure half-time was calculated as the interval between peak transmitral velocity and velocity divided by the square root of 2, as measured from the outer border of the spectral envelope. Doppler mitral valve area (MVA) was obtained with the equation: MVA = 220 divided by pressure half-time. For catheterization data, the pressure half-time was measured directly from simultaneously recorded left ventricular and left atrial pressure (18 patients) or pulmonary capillary wedge pressure (49 patients). The catheterization half-time was taken as the time required for the peak pressure gradient to fall to one half of the initial value. Calculations of the mitral valve area at catheterization were obtained by the Gorlin equation with pressure gradient and cardiac output determinations. Mitral valve area as determined by the Gorlin equation for all cases ranged from 0.4 to 2.0 (mean = 1.03 +/- 0.37) cm2. Linear regression analysis that compared cardiac catheterization and Doppler half-times yielded r = 0.68. For the subgroup of patients with sinus rhythm, the correlation improved to r = 0.76. 