Combined use of pulsed and color M-mode Doppler echocardiography for the estimation of pulmonary capillary wedge pressure: an empirical approach based on an analytical relation.

OBJECTIVES We sought a noninvasive estimation of pulmonary capillary wedge pressure (Pw) by means of the information obtained from transmitral pulsed Doppler and color M-mode Doppler flow propagation velocity (FPV). BACKGROUND Pulsed Doppler parameters have limited accuracy for the estimation of Pw because they are determined by left atrial pressure and other parameters such as ventricular relaxation. Recently, a good correlation has been found between the rate of ventricular relaxation (tau, tau) and FPV measured by color M-mode Doppler echocardiography. METHODS We studied 20 patients who underwent invasive hemodynamic monitoring. By multilinear regression analysis, the relationships between Pw and Doppler parameters, FPV, and a noninvasive estimate (P(est)) based on the Weiss' equation (substituting tau for 1/FPV) were determined. A simplified index based on the results obtained was then tested in an additional group of 34 patients. RESULTS By multiple regression analysis only isovolumic relaxation time (IVRT) (p = 0.0096) and P(est) (p = 0.0043) were related to Pw. A derived empirical index, 10(3)/([2 x IVRT] + FPV), was strongly correlated with Pw in the entire group according to the regression equation Pw = 4.5 x (10(3)/[[2 x IVRT] + FPV]) - 9 (r = 0.89, p < 0.0001, [standard error of the estimate] SEE = 3.3 mm Hg). The sensitivity and specificity for the prediction of Pw > 15 mm Hg were 90% and 100%, respectively. CONCLUSIONS The combined use of FPV as a surrogate for tau and IVRT permits a close prediction of Pw.