[Value and limitations of the pressure halftime method for quantitating the mitral valve area in mitral stenosis]

To evaluate the accuracy of the pressure half-time (PHT) method in predicting the anatomical mitral valve area (Aa) in mitral stenosis, Doppler echocardiography was performed in 42 cases with mitral stenosis within 48 hours before mitral valve replacement. The diastolic mitral flow velocities were recorded by the continuous wave Doppler technique, and PHT and the derived mitral valve area (Ad) were measured by a computer system from the Doppler spectrum. Aa was measured from a photograph of the mitral valve excited en bloc at surgery. The comparison between Aa and Ad yielded a good correlation (r = 0.85). However, Ad significantly underestimated Aa (P less than 0.001) in cases with combined mitral stenosis and regurgitation, and significantly overestimated Aa in cases with combined mitral and aortic lesions. There was also a large scatter of data obtained by the two measurements (SEE = 0.41 cm2). It is concluded that the PHT method can predict Aa in isolated mitral stenosis with an acceptable accuracy but is of only limited value in combined mitral stenosis and regurgitation or combined mitral and aortic valve lesions.