0089 : Echocardiography and right ventricular function: validation of functional criteria compared to in-vivo and ex-vivo contractility parameters

Abstract

Right ventricular (RV) dysfunction is a major determinant of long-term survival in congenital heart diseases. Early echocardiographic detection of RV failure is mandatory, but recent parameters need to be validated. Objectives were to: (1) validate standard and strain echocardiographic parameters for evaluation of RV systolic function, compared to hemodynamic parameters; (2) assess the accuracy of these parameters for early detection of RV failure. Combined RV overload as observed in repaired tetralogy of Fallot was surgically reproduced in 2-month-old piglets (n=6). Age-matched piglets were used as controls (n=4). RV function was evaluated at baseline and 4 months of follow-up by standard and strain echocardiographic parameters, compared to hemodynamic (conductance catheter). Sarcomere shortening and calcium transients were recorded in RV isolated myocytes (IonOptix). Contractile reserve was assessed by in-vivo (dobutamine 5奯kg) and ex-vivo (isoprenaline 100nM) ?-adrenergic stimulation. 4 months after surgery, hemodynamic RV ejection fraction (FEVD) was significantly decreased (29.7% [26.2-34] vs 42.9% [40.7-48.6], p<0.01), and inotropic responses to dobutamine were attenuated (contractile reserve ΔEmax = 51% vs 193% for controls). On echocardiography FAC, TAPSE, S’ peak and RV free wall longitudinal strain rate were significantly decreased and correlated with FEVD. Strain rate and S’ peak were correlated with ?Emax (r=0.75 and 0.78, p<0.05). Isolated RV myocytes from operated animals exhibited hypertrophy, decreased sarcomere shortening peak in response to isporenaline (ΔL= 7.8 ± 2.8% vs 10.7 ± 2.9%, p<0.05), and increased spontaneous calcium waves suggesting perturbations of calcium homeostasis. In this model, both standard and strain echocardiographic parameters allowed the detection of early impairments of RV function and cardiac reserve, which are associated with cardiac excitation-contraction coupling alterations.