Determination of pulmonary capillary wedge pressure using pulsed wave Doppler echocardiography: clinical application of range ambiguity phenomenon.

To predict pulmonary capillary wedge pressure (PCWP) noninvasively, several Doppler combination indices have been developed. Recently, a fair correlation has been found between the time constant of isovolumic left ventricular (LV) relaxation (tau) and pulsed wave Doppler LV inflow propagation velocity (LVIPVpw) derived through the application of range ambiguity phenomenon. In the measurement of LVIPVpw, we can simultaneously measure the peak phantom E-wave velocity (Ep) from the same heartbeat. Hence, it is hypothesized that Ep/LVIPVpw is a useful index in predicting PCWP. In all, 29 patients who underwent elective cardiac catheterization for suggested coronary artery disease were included. Mean PCWP (mPCWP) obtained from right heart catheterization was compared with echocardiographic data before and 5 minutes after sublingual application of nitroglycerin (0.6 mg). Nitroglycerin caused a significant decrease in Ep and mPCWP, but not in LVIPVpw (P < .001, P < .001, and P = .687, respectively). By stepwise multiple linear regression analysis, only the Ep/LVIPVpw (beta = 0.832, P < .001) was the independent predictor of mPCWP. After nitroglycerin intake, the change in mPCWP was significantly correlated with the change in Ep/LVIPVpw (r = 0.455, P = .015). The sensitivity and specificity of Ep/LVIPVpw > 0.74 in predicting mPCWP > 15 mm Hg were 78% and 90%, respectively (area under curve 0.86). In conclusion, Ep/LVIPVpw derived from the same heartbeat provides a good estimate of mPCWP and can be used to rapidly track the change in mPCWP.