[1] Department of Paediatric Cardiology, Royal Hospital for Children, Bristol BS2 8BJ, Upper Maudlin Street
[2] Department of Paediatric Cardiology, Guy's Hospital, London SE1 9RT, St Thomas' Street
[3] Department of Paediatrics, Ealing Hospital, Southall, Middlesex UB1 3EW, Uxbridge Road
[4] Institute of Psychiatry, London SE5 8AF, De Crespigny Park