Determination of the mean pressure gradient in mitral stenosis by Doppler echocardiography.

Measurement of the mean pressure gradient provides an important estimation of the severity of mitral stenosis. However, determination of the mean pressure gradient from Doppler recordings has been unsatisfactory using previously described methods. In this study, a new method calculating the mean pressure gradient, the integral method is described. It was developed from mathematical analysis of Doppler velocity curves. Doppler echocardiography and cardiac catheterisation were performed in 23 patients with mitral stenosis to evaluate the accuracy of three current mathematical methods of determining the mean pressure gradient. The mean pressure gradients calculated by the three methods correlated highly with that measured by catheterisation (r = 0.93). However, the mean pressure gradients calculated by the previously described mean velocity square method and the arithmetical average method underestimated significantly that measured by cardiac catheterisation. In contrast, there was no significant difference between the mean pressure gradients calculated by the integral method and measured by cardiac catheterisation. These results confirm the usefulness of Doppler echocardiography for determining the mean pressure gradient in mitral stenosis and demonstrate that among current methods, the integral method provides the most accurate calculations of the mean pressure gradient.