1. Cardiac Surgery Unit; A.O.U. “Policlinico-Vittorio Emanuele”; Ferrarotto Hospital; University of Catania; Catania Italy
2. Heart Center; Fondazione “G.B Morgagni”; Pedara, Catania Italy
3. Heart Center; Turku University Hospital; Turku Finland
4. Department of Surgery; University of Turku; Turku Finland
5. Department of Surgery; University of Oulu; Oulu Finland
6. Cardiology Unit, A.O.U. “Policlinico-Vittorio Emanuele”; Ferrarotto Hospital; University of Catania; Catania Italy
7. Department of Biomedical and Biotechnological Sciences; University of Catania; Catania Italy