Background:Several non-invasive methods for measuring pulmonary vascular resistance (PVR) have been proposed to date, but they remain empirical, lacking sufficient accuracy to be used in clinical practice. The aims of this study were to propose a novel echocardiographic measurement of PVR based on a theoretical formula and investigate the feasibilty and accuracy of this method in patients with heart failure.Methods and Results:Echocardiography was performed in 27 patients before right heart catheterization. Peak tricuspid regurgitation pressure gradient (TRPG), pulmonary regurgitation pressure gradient in end-diastole (PRPG_ed), and cardiac output derived from the time-velocity integral and the diameter in the left ventricular outflow tract (CO_LVOT) were measured. PVR based on a theoretical formula (PVR_theo) was calculated as (TRPG–PRPG_ed)/3CO_LVOTin Wood units (WU). The results were compared with PVR obtained by right heart catheterization (PVR_cath) using linear regression and Bland-Altman analysis. Mean PVR_cathwas 2.4±1.4 WU. PVR_theocorrelated well with PVR_cath(r=0.83, P<0.001). On Bland-Altman analysis the mean difference was 0.1±0.7 WU. The limits of agreements were smaller than for other non-invasive estimations previously reported.Conclusions:The new echocardiographic approach based on a theoretical formula provides a non-invasive and accurate assessment of PVR in patients with heart failure. (Circ J 2015; 79: 2408–2413)