Accurate noninvasive estimation of pulmonary vascular resistance by Doppler echocardiography in patients with chronic heart failure

OBJECTIVES This study was undertaken to explore further the relationship between Doppler-derived parameters of pulmonary flow and pulmonary vascular resistance (PVR) and to determine whether PVR could be accurately estimated noninvasively from Doppler flow velocity measurements in patients with chronic heart failure. BACKGROUND The assessment of PVR is of great importance in the management of patients with heart failure. However, because of the inconclusive and conflicting data available, Doppler estimation of PVR is still considered unreliable. METHODS Simultaneous Doppler echocardiographic examination and right heart catheterization were performed in 63 consecutive sinus rhythm heart failure patients with severe left ventricular systolic dysfunction. Hemodynamic PVR was calculated with the standard formula. The following Doppler variables on pulmonary flow and tricuspid regurgitation velocity curve were correlated with PVR: maximal systolic flow velocity, pre-ejection period (PEP), acceleration time (AcT), ejection time, total systolic time (TT), velocity time integral, and right atrium-ventricular gradient. RESULTS At univariate analysis, all variables except maximal systolic flow velocity and velocity time integral showed a significant, although weak, correlation with PVR. The best correlation found was between AcT and PVR (r = −0.68). By regression analysis, only PEP, AcT and TT entered into the final equation, with a cumulative R = 0.87. When the function (PEP/AcT)/TT was correlated with PVR, the correlation coefficient further improved to 0.96. Of note, this function prospectively predicted PVR (r = 0.94) after effective unloading manipulations. CONCLUSIONS The analysis of Doppler-derived pulmonary systolic flow is a reliable and accurate tool for estimating and monitoring PVR in patients with chronic heart failure due to left ventricular systolic dysfunction.