A new method to estimate pulmonary vascular resistance using diastolic pulmonary artery-right ventricular pressure gradients derived from continuous-wave Doppler velocity measurements of pulmonary regurgitation

Echocardiographic estimation of right ventricular diastolic stiffness based on pulmonary regurgitant velocity waveform analysis in precapillary pulmonary hypertension

Right ventricular (RV) diastolic stiffness is an independent predictor of survival and is strongly associated with disease severity in patients with precapillary pulmonary hypertension (PH). Therefore, a fully validated echocardiographic method for assessing RV diastolic stiffness needs to be established. This study aimed to compare echocardiography-derived RV diastolic stiffness and invasively measured pressure-volume loop-derived RV diastolic stiffness in patients with precapillary PH. We studied 50 consecutive patients with suspected or confirmed precapillary PH who underwent cardiac catheterization, magnetic resonance imaging, and echocardiography within a 1-week interval. Single-beat RV pressure-volume analysis was performed to determine the gold standard for RV diastolic stiffness. Elevated RV end-diastolic pressure (RVEDP) was defined as RVEDP ≥ 8 mmHg. Using continuous-wave Doppler and M-mode echocardiography, an echocardiographic index of RV diastolic stiffness was calculated as the ratio of the atrial-systolic descent of the pulmonary artery-RV pressure gradient derived from pulmonary regurgitant velocity (PRPGDAC) to the tricuspid annular plane movement during atrial contraction (TAPMAC). PRPGDAC/TAPMAC showed significant correlation with β (r = 0.54, p < 0.001) and RVEDP (r = 0.61, p < 0.001). A cut-off value of 0.74 mmHg/mm for PRPGDAC/TAPMAC showed 83% sensitivity and 93% specificity for identifying elevated RVEDP. Multivariate analyses indicated that PRPGDAC/TAPMAC was independently associated with disease severity in patients with precapillary PH, including substantial PH symptoms, stroke volume index, right atrial size, and pressure. PRPGDAC/TAPMAC, based on pulmonary regurgitation velocity waveform analysis, is useful for the noninvasive assessment of RV diastolic stiffness and is associated with prognostic risk factors in precapillary PH.

A simpler noninvasive method of predicting markedly elevated pulmonary vascular resistance in patients with chronic thromboembolic pulmonary hypertension

Several echocardiographic methods to estimate pulmonary vascular resistance (PVR) have been proposed. So far, most studies have focused on relatively low PVR in patients with a nonspecific type of pulmonary hypertension. We aimed to clarify the clinical usefulness of a new echocardiographic index for evaluating markedly elevated PVR in chronic thromboembolic pulmonary hypertension (CTEPH). We studied 127 CTEPH patients. We estimated the systolic and mean pulmonary artery pressure using echocardiography (sPAPEcho, mPAPEcho) and measured the left ventricular internal diameter at end diastole (LVIDd). sPAPEcho/LVIDd and mPAPEcho/LVIDd were then correlated with invasive PVR. Using receiver operating characteristic curve analysis, a cutoff value for the index was generated to identify patients with PVR > 1000 dyn·s·cm-5. We analyzed pre- and postoperative hemodynamics and echocardiographic data in 49 patients who underwent pulmonary endarterectomy (PEA). In this study, mPAPEcho/LVIDd moderately correlated with PVR (r = 0.51, p < 0.0001). There was a better correlation between PVR and sPAPEcho/LVIDd (r = 0.61, p < 0.0001). sPAPEcho/LVIDd ≥ 1.94 had an 77.1% sensitivity and 75.4% specificity to determine PVR > 1000 dyn·s·cm-5 (area under curve = 0.804, p < 0.0001, 95% confidence interval [CI], 0.66-0.90). DeLong's method showed there was a statistically significant difference between sPAPEcho/LVIDd with tricuspid regurgitation velocity2/velocity-time integral of the right ventricular outflow tract (difference between areas 0.14, 95% CI, 0.00-0.27). The sPAPEcho/LVIDd and mPAPEcho/LVIDd significantly decreased after PEA (both p < 0.0001). The sPAPEcho/LVIDd and mPAPEcho/LVIDd reduction rate (ΔsPAPEcho/LVIDd and ΔmPAPEcho/LVIDd) was significantly correlated with PVR reduction rate (ΔPVR), respectively (r = 0.58, p < 0.01; r = 0.69, p < 0.05). In conclusion, the index of sPAPEcho/LVIDd could be a simpler and reliable method in estimating CTEPH with markedly elevated PVR and also be a convenient method of estimating PVR both before and after PEA.

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_AC) and tricuspid annular plane movement during atrial contraction (TAPM_AC). We studied 81 consecutive patients with various cardiac diseases who underwent echocardiography and cardiac catheterization. We measured PRPGD_AC and TAPM_AC using continuous-wave Doppler and M-mode echocardiography, respectively, and calculated PRPGD_AC/TAPM_AC. RV end-diastolic pressure (RVEDP) and RV pressure increase during atrial contraction (ΔRVP_AC) were invasively measured, and RV volume change during atrial contraction (ΔV_AC) was calculated from echocardiographic late-diastolic transtricuspid flow time-velocity integral and tricuspid annular area; thus ΔRVP_AC/ΔV_AC was used as the standard index for RV operating stiffness. PRPGD_AC/TAPM_AC well correlated with ΔRVP_AC/ΔV_AC (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_AC/TAPM_AC was the single independent determinant of ΔRVP_AC/ΔV_AC (β = 0.86, p < 0.001). PRPGD_AC/TAPM_AC is useful to estimate RV operating stiffness and a good practical indicator of RVEDP.