Abstract 10567: Systolic and Diastolic Myocardial Stiffness of the Right Ventricle Free Wall Assessed by Ultrafast Ultrasound Imaging in Humans: Comparison with Pressure-Volume Loop in Healthy Volunteers and Pulmonary Arterial Hypertension Patients

Abstract

Background: Echocardiographic parameters to assess systolic and diastolic RV function are strongly dependent on loading conditions. Myocardial stiffness (MS) is an intrinsic myocardial property that influences both diastolic and systolic cardiac function. MS is independent of loading conditions and pre-clinical studies have demonstrated a correlation between 1) systolic MS and contractility (or ESPVR); 2) end-diastolic MS and compliance (or EDPVR). Shear wave imaging (SWI) by ultrafast ultrasound imaging allows quantitative MS assessment at any time of the cardiac cycle. This noninvasive technique could provide load-independent measure of RV function. Methods (figure 1): Ten children, 5 pulmonary arterial hypertension patients (PAH) undergoing diagnostic right heart catheterization (RHC) were prospectively enrolled as well as 5 age-matched heathy volunteers (HV). MS was assessed at baseline and during FiO2 70%+40ppm NO for the PAH group. MS in the RV free wall using SWI every 100ms during the cardiac cycle. RV-ESPVR and RV-EDPVR were assessed by pressure-volume loops using a pressure catheter and real-time 3D-echo volumes. Results (figure 2): MS increased significatively in systole compared to end-diastole in both groups (p<0.01) and more significantly in the PAH group (p<0.01). In the PAH group, no difference was found in systolic MS between baseline and during FiO2 70%+40ppm NO (p=0.67). Systolic MS correlated with RV-ESPVR (r=0.75). End-diastolic MS correlated with RV-EDP (r=0.76) and RV-EDPVR (r=0.85). Conclusions: Our preliminary data demonstrate that MS could be a quantitative measure of RV contractility and diastolic compliance of the RV.