Simple and noninvasive method to estimate right ventricular operating stiffness based on echocardiographic pulmonary regurgitant velocity and tricuspid annular plane movement measurements during atrial contraction.

It was recently shown that invasively determined right ventricular (RV) stiffness was more closely related to the prognosis of patients with pulmonary hypertension than RV systolic function. So far, a completely noninvasive method to access RV stiffness has not been reported. We aimed to clarify the clinical usefulness of our new echocardiographic index of RV operating stiffness using atrial-systolic descent of the pulmonary artery-RV pressure gradient derived from pulmonary regurgitant velocity (PRPGD) and tricuspid annular plane movement during atrial contraction (TAPM). We studied 81 consecutive patients with various cardiac diseases who underwent echocardiography and cardiac catheterization. We measured PRPGD and TAPM using continuous-wave Doppler and M-mode echocardiography, respectively, and calculated PRPGD/TAPM. RV end-diastolic pressure (RVEDP) and RV pressure increase during atrial contraction (ΔRVP) were invasively measured, and RV volume change during atrial contraction (ΔV) was calculated from echocardiographic late-diastolic transtricuspid flow time-velocity integral and tricuspid annular area; thus ΔRVP/ΔV was used as the standard index for RV operating stiffness. PRPGD/TAPM well correlated with ΔRVP/ΔV (r = 0.84, p < 0.001) and RVEDP (r = 0.80, p < 0.001), and the area under the receiver operating characteristic curve to discriminate RVEDP > 12 mmHg was 0.94. Multivariate regression analysis revealed that PRPGD/TAPM was the single independent determinant of ΔRVP/ΔV (β = 0.86, p < 0.001). PRPGD/TAPM is useful to estimate RV operating stiffness and a good practical indicator of RVEDP.