1. Department of Cardiac Surgery, Onassis Cardiac Surgery Center, 17674 Athens, Greece
2. Cardiothoracic Surgery Unit, Great Ormond Street Hospital for Children, WC1N 3JH London, UK
3. Propaedeutic Surgery First Department, University of Athens, 11527 Athens, Greece
4. Laboratory of Clinical Virology, Medical School, University of Crete, 71003 Heraklion, Crete, Greece