Determination of the transvalvular gradient using continuous wave Doppler in patients with mitral stenosis. Correlation with the hemodynamic method

In order to assess the reliability of Doppler echocardiography in the determination of mean mitral gradient 38 consecutive patients (pts) affected by rheumatic mitral valve stenosis (MS) were analyzed by continuous wave Doppler echocardiography (CWD). Cardiac catheterization (CATH) was performed within 24 hours from echocardiographic examination. The mean diastolic mitral gradient (MG) at CATH was calculated by planimetry from simultaneously recorded left ventricular and pulmonary artery wedge pressure. The maximal velocity profile through the mitral valve was used to calculate pressure gradient by CWD. A mean mitral gradient was calculated for each patient by the planimetered velocity profile throughout diastole. MG determined by CATH ranged from 6 to 31 mmHg (mean 15.2 +/- 6.0); MG determined by CWD ranged from 4 to 18 mmHg (mean 10 +/- 3.7). The correlation between CWD and CATH by linear regression analysis was: y = 0.53 X + 1.8; r = 0.85; p less than 0.001. Mean % error of CWD in the assessment of MG was 34.7%. In conclusion this study indicates that CWD seems systematically underestimate MG with respect to CATH. The identification of CWD flow tracings "optimal" for analysis could not represent the maximal velocity of transmitral jet, which is a complex three dimensional entity. In addition non-simultaneous determinations of gradient and day-to-day variations in cardiac output may account for discrepancies between CWD and CATH measurements.