Restrictive left ventricular filling and preserved ventricular function:: A limitation in the noninvasive estimation of pulmonary wedge pressure by Doppler echocardiography

Pulmonary wedge pressure (PWP) can be estimated from the ratio of transmitral early peak flow velocity to flow propagation velocity measured by Doppler. Discrepancies observed in the application of the method prompted us to design this prospective study, aimed at detecting potential limitations of the method. We studied a total of 32 patients admitted to a cardiac intensive care unit, using a Swan-Ganz catheter. Correlation between invasive- and Doppler-estimated PWP was fairly good (r = 0.58). Analysis of discrepant cases led to the identification of a subgroup of 6 patients In whom PWP was largely underestimated because of unexpectedly high values of flow propagation velocity (71 +/- 15 cm/s vs 37 +/- 10 cm/s in the rest of the group; P = .0001). All of them had in common a restrictive Doppler filling pattern and preserved left ventricular systolic function. Exclusion of this group showed an improvement in the correlation coefficient to r = 0.72. In conclusion, PWP can be estimated by the Doppler early peak flow velocity to flow propagation velocity ratio, although a significant underestimation of PWP may be observed in patients with a restrictive filling pattern and preserved ventricular function.