1 Paediatric Cardiology Services, Royal Brompton Hospital and Harefield NHS Foundation Trust, United Kingdom of Great Britain and Northern Ireland; National Heart and Lung Institute, Imperial College London, United Kingdom of Great Britain and Northern Ireland. Electronic address: a.fraisse@rbht.nhs.uk.
2 Paediatric Cardiology Services, Royal Brompton Hospital and Harefield NHS Foundation Trust, United Kingdom of Great Britain and Northern Ireland; National Heart and Lung Institute, Imperial College London, United Kingdom of Great Britain and Northern Ireland.