1. From the Centre for Cardiovascular Imaging, UCL Institute of Cardiovascular Science, London, United Kingdom (B.P., M.A.Q., J.A.S., A.M.T., V.M.); Cardiorespiratory Division, Great Ormond Street Hospital for Children, London, United Kingdom (I.S.-N., G.D., S.M.); Adult Congenital Heart Disease Department, The Heart Hospital, University College London Hospitals, London, United Kingdom (B.P.); Pediatric Respiratory Medicine, The Royal Brompton Hospital, London, United Kingdom (A.M.); INSERM, U947,...