1. Department of Cardiovascular Imaging, Great Ormond Street Hospital for Children NHS Foundation Trust , London , WC1N 3JH UK
2. Department of Adult Congenital Heart Disease, Liverpool Heart and Chest NHS Trust , Liverpool L14 3PE , UK
3. Cardiology Department, Royal Berkshire Hospital , Reading RG1 5AN , UK
4. Adult Congenital Heart Centre and Centre for Pulmonary Hypertension, Royal Brompton Hospital, Royal Brompton & Harefield Hospitals, Guy's and St Thomas'; NHS Foundation Trust , London SW3 6NP , UK
5. National Heart and Lung Institute, Imperial College London , London SW3 6LY , UK
6. Department of Cardiology, Queen Elizabeth Hospital Birmingham, University Hospitals Birmingham NHS Foundation Trust , Birmingham B15 2GW , UK