1. Department of Surgery, General University Hospital of Patras, 26504 Patras, Greece
2. General Surgery, Epsom and St. Helier University Hospitals, National Health Service (NHS) Trust, London SM5 1AA, UK
3. Department of Cardiothoracic Surgery, General Hospital of Athens “Ippokrateio”, 11527 Athens, Greece
4. Department of Cardiothoracic and Vascular Surgery, Westpfalz-Klinikum, 67655 Kaiserslautern, Germany