1 Adult Congenital Heart Centre and National Centre for Pulmonary Hypertension, Royal Brompton & Harefield NHS Trust, London, UK. Electronic address: ioannis.kasouridis@doctors.org.uk.
2 Adult Congenital Heart Centre and National Centre for Pulmonary Hypertension, Royal Brompton & Harefield NHS Trust, London, UK.
3 Adult Congenital Heart Centre and National Centre for Pulmonary Hypertension, Royal Brompton & Harefield NHS Trust, London, UK; National Heart and Lung Institute, Imperial College, London, UK.