Study of Adaptation of the Right Ventricle to Systemic Afterload

Right ventricle (RV) in sub-aortic position is a rare situation, mainly in two congenital heart defects: congenitally corrected transposition of the great arteries and complete transposition of the great arteries palliated by atrial switch. In these patients, increase of afterload leads to hypertrophy and late RV dilatation. The stress exercised on RV walls could play a role in adaptative mechanisms to systemic afterload. Beyond a remodelling threshold, it could cause fibrosis damage and RV systolic failure. Magnetic resonance imaging, which has a major potential in estimation of RV remodelling, wall stress and fibrosis, could shed light on RV adaptation to systemic afterload and evolution towards failure. Systemic RV remodelling and function could also depend on the neuro-hormone secretion and mechanical arterial properties, that have a direct influence on patients afterload. The first purpose of the study is to determine the adaptative mechanisms of RV to systemic afterload, and the mechanisms of RV failure, in patients with congenital heart disease and subaortic RV, using cardiac magnetic resonance imaging (CMR).The mechanisms are evaluated by measures of RV remodelling and RV wall stress using CMR. Second objectives are to evaluate these mechanisms using echography, arterial properties study and neurohormonal levels