[1] Great Ormond St Hosp NHS Fdn Trust, Cardiac Crit Care & Resp Div, Great Ormond St, London WC1N 3JH, England
[2] UCL, Clin Operat Res Unit, London, England
[3] Evelina London Childrens Hosp, Dept Paediat Cardiol & Cardiac Surg, London, England
[4] Bristol Royal Hosp Children, Paediat Intens Care Unit, Bristol, Avon, England
[5] Royal Brompton & Harefield NHS Fdn Trust, Paediat Cardiol Dept, London, England
[6] Birmingham Childrens Hosp, Dept Cardiac Surg, Birmingham, W Midlands, England
[7] Royal Hosp Children Yorkhill, Dept Paediat Intens Care, Glasgow, Lanark, Scotland
[8] Royal Hosp Children Yorkhill, Dept Paediat Cardiac Surg, Glasgow, Lanark, Scotland
[9] Univ Hosp Birmingham, Dept Cardiol, Birmingham, W Midlands, England