Abstract 17062: A Novel Non-Invasive Index to Characterize Right Ventricle-Pulmonary Arterial Vascular Coupling in Children

Abstract

Introduction: The right ventricle (RV) is a pulsatile pump, the efficiency or work of which depends on proper hemodynamic coupling with the compliant pulmonary arterial vasculature (PV). RV-PV coupling derived by right heart catheritization (RHC) measures the ratio of ventricular elastance (Ees, contractility) to arterial elastance (Ea, afterload) and is based on the work-energy principle that states a change in energy is equal to the work expended by a force through displacement. Non-invasive echocardiography derived surrogates to the Ees/Ea ratio that account for the length-force relationship have been proposed, but their clinical correlation as estimates of RV-PV coupling remain to be established. Hypothesis: We hypothesize that the non-invasive index of RV length-force relationship is a reliable measure of invasive RV-PV coupling (Ees/Ea) in children. Methods: Prospectively acquired simultaneous echocardiography-derived ratio of tricuspid annular plane systolic excursion to pulmonary artery acceleration time (TAPSE/PAAT) and RHC-derived Ees/Ea were compared using regression analysis in a cohort of 125 children (median age, 5 years; IQR, 1-13 years) with a wide range of pulmonary hemodynamics. Ees/Ea was calculated using the single beat method from RHC measures with the following equation: (RV systolic pressure - mean pulmonary artery pressure) / mean pulmonary artery pressure. TAPSE (mm), as a measure of RV contractile reserve, was substituted for length, and PAAT (msec), a reliable estimate of RV afterload, was exchanged for force. PAAT was adjusted for RV ejection time (PAATi=PAAT/RVET) to account for heart rate variability. Results: TAPSE/PAAT and TAPSE/PAATi both correlated with invasive Ees/Ea (r = 0.81, p<0.01 and r=0.76, p<0.01, respectively, Figure). TAPSE/PAAT and TAPSE/PAATi were both decreased (p<0.001) in children with pulmonary hypertension by RHC (mPAP>25 mmHg and PVRi>3 WU.m2). With ROC analysis, TAPSE/PAAT < 0.13 m/sec and TAPSE/PAATi < 38 mm detected Ees/Ea < 1.0 with sensitivity of 95% and specificity of 91% with an AUC of 0.90 (95% CI, 0.85-0.96). Conclusions: TAPSE/PAAT and TAPSE/PAATi , non-invasive indices of the length-force relationship, provide reliable estimates of invasive RV-PV coupling in children.