Assessing Mitral Stenosis with Doppler Echocardiography Limitations of the Pressure Half-Time Method

Echocardiographic techniques have been used exten-sively in the noninvasive evaluation of mitral stenosis. Although mitral valve area can be reliably predicted by two-dimensional echocardiography (2DE) in selected patients, neither M-mode nor 2DE techniques provide any direct hemodynamic information. The subsequent utilization of Doppler techniques allows for interro-gation of coexistent blood flow alterations and an estimate of the pressure gradient across the mitral valve using the modified Bernoulli equation. Since the pressure gradient is found to vary with flow volume, an additional Doppler technique using the concept of pressure half-time provides an assessment of the severity of mitral stenosis that is related to mitral valve area and independent of hemodynamic factors. Although several studies reporting good reliability have contributed to the widespread acceptance of the pressure half-time concept, recent reports have indicated significant limitations with the pressure half-time method leading to inaccuracies and poor reliability in predicting the mitral valve area. This review discusses the development of the pressure half-time concept and the implications of these recent research findings on the critical use of the Doppler pressure half-time method to estimate the mitral valve area