[1] Evelina Childrens Hosp, Dept Congenital Cardiol, London SE1 7EH, England
[2] Childrens Hosp, Inst Child Hlth, Dept Paediat Cardiol, Lahore, Pakistan
[3] Punjab Inst Cardiol, Lahore, Pakistan
[4] Childrens Mem Hlth Inst, Heart Catheterizat Lab, Warsaw, Poland
[5] Leeds Gen Infirm, Dept Congenital Cardiol, Leeds, W Yorkshire, England