[1] Great Ormond St Hosp Natl Hlth Serv Fdn Trust, Cardiac & Crit Care Div, Great Ormond St, London, England
[2] UCL Great Ormond St Inst Child Hlth, Populat Policy & Practice Programme, London, England
[3] UCL, Clin Operat Res Unit, London, England
[4] Evelina London Childrens Hosp, Dept Paediat Cardiol & Cardiac Surg, London, England
[5] Birmingham Childrens Hosp, Dept Intens Care & Paediat Cardiac Surg, Birmingham, W Midlands, England
[6] Bristol Royal Childrens Hosp, Paediat Intens Care Unit, Bristol, Avon, England
[7] Bristol Royal Childrens Hosp, Dept Paediat Cardiac Surg, Bristol, Avon, England
[8] Royal Hosp Children, Dept Intens Care & Paediat Cardiac Surg, Glasgow, Lanark, Scotland