[1] Univ Padua, Dept Cardiovasc Surg, Pediat Cardiac Surg Unit, I-35128 Padua, Italy
[2] Queen Silvia Childrens Hosp, Gothenburg, Sweden
[3] Childrens Hosp, Birmingham B16 8ET, W Midlands, England
[4] Gasthuisberg Univ Ziekenhuis, Louvain, Belgium
[5] Osped Pediat Bambino Gesu, Rome, Italy
[6] Natl Hosp, Rikshosp, Oslo, Norway
[7] CHU Vaudois, CH-1011 Lausanne, Switzerland
[8] Hosp Santa Maria, Lisbon, Portugal
[9] Great Ormond St Hosp Sick Children, Cardiac Unit, London WC1N 3JH, England
[10] Childrens Hosp, Bratislava, Slovakia
[11] Gyermeksziv Kozpont, Gottsegen Gyorgy Orszagos Kardiologiai Intezet, Budapest, Hungary
[12] Eppendorf Univ Hosp, Hamburg, Germany
[13] Childrens Mem Hlth Inst, Warsaw, Poland
[14] Clin Univ St Luc, B-1200 Brussels, Belgium
[15] Univ Helsinki, Hosp Children & Adolescents, Helsinki, Finland
[16] Onassis Cardiac Surg Ctr, Athens, Greece
[17] Deutsch Kinderherzzentrum, St Augustin, Germany
[18] Gen Infirm, Yorkshire Heart Ctr, Leeds LS1 3EX, W Yorkshire, England
[19] Univ Tubingen, Tubingen, Germany