[1] Stt Georges Univ London, Inst Med & Biomed Educ, London, England
[2] Univ Birmingham, Coll Med & Dent Sci, Birmingham, W Midlands, England
[3] Queens Univ Belfast, Sch Med, Belfast, Antrim, North Ireland
[4] Liverpool Heart & Chest Hosp, Dept Cardiothorac Surg, Liverpool, Merseyside, England
[5] Alder Hey Children Hosp, Dept Cardiac Surg, E Prescot Rd, Liverpool L14 5AB, Merseyside, England
[6] Univ Liverpool, Liverpool Ctr Cardiovasc Sci, Liverpool, Merseyside, England
[7] Heart & Chest Hosp, Liverpool, Merseyside, England