[Continuous wave Doppler measurement of transmitral pressure gradients in mitral stenosis: comparisons with...

To determine the accuracy and reliability of measurements of mitral flow velocity and pressure gradients obtained from continuous wave Doppler (CWD) echocardiography, the left ventricular pressure, pulmonary capillary wedge pressure and CWD echo were simultaneously recorded simultaneously for 22 patients with mitral stenosis. An ultrasonic transducer was placed over the left ventricular apex to direct the ultrasonic beam parallel with the mitral flow. High-pitched audio signals were used to determine whether the ultrasonic beam direction was appropriate. The angle formed by the beam direction and the blood flow was assumed to be zero when a good Doppler echo was recorded. The maximum flow velocity and pressure gradients calculated from CWD echo were compared with pressure gradients obtained by catheterization. These were analyzed during the same heart beats. The results were as follows: Good recordings of pressures and CWD echograms were obtained for 17 patients, and their data were used for the analysis. The maximum flow velocity through the mitral valve obtained by CWD echography was very similar to the pressure gradients obtained by catheterization in terms of phases and patterns. The pressure gradients (x) calculated from CWD using a simplified Bernoulli's equation correlated well with those (y) measured at the same time on pressure tracings (y = 1.2x + 1.5, r = 0.92, p less than 0.001). Mean diastolic pressure gradients (X) obtained by CWD echography also correlated well with those (Y) recorded at catheterization (Y = 1.2X + 0.15, r = 0.95). Based on these results, we conclude that CWD echography is a reliable, noninvasive method to measure the pressure gradient across the mitral valve in patients with mitral stenosis.