Right ventricular hypertrophy after atrial switch operation: Normal adaptation process or risk factor? A cardiac magnetic resonance study

Abstract

Background: Systemic right ventricle (RV) hypertrophy and impaired function occur after atrial switch for dextrotransposition of the great arteries (d-TGA). Echocardiography is limited in its ability to assess the RV. We sought to evaluate systemic RV myocardial-mass index (MMI) and function after atrial switch and to analyse the role of hypertrophy for ventricular function with special consideration of the interventricular septal (IVS) movement. Methods: Thirty-seven consecutive patients (median age 22.9 years) after atrial switch were studied using cardiac magnetic resonance imaging (1.5T Intera, Philips) with a dedicated 5-channel phased-array surface cardiac coil. Cine steady-state free-precession sequences were acquired to obtain myocardial masses and function. The systolic movement of the IVS was defined as positive when moving towards the centroid of the RV and was defined as nonpositive otherwise. Patient parameters were compared to controls. Results: The systemic RVs were significantly larger (p < 0.001) than the left ventricles of the control group, systolic function was significantly impaired (p < 0.001) and MMI including the IVS was comparable (p = n.s.). RV-MMI excluding the IVS and RV ejection fraction (EF) demonstrated a quadratic correlation (r = 0.6, p< 0.001), meaning that patients with RV-MMI ≤29 g/m2 and ≥68 g/m2 had a reduced level of systolic function. Positive septal movement improved RV function compared with nonpositive septal movement (p = 0.024). Conclusions: There seems to be a range of beneficial RV hypertrophy after atrial switch in which a sufficient RV-EF can be expected. A positive septal movement, probably the resultofhypertrophic septal RVfibres, improvesRVfunction and might be regarded as a beneficial contraction pattern. © The Author(s) 2012.