1. Cardiothoracic Surgery Department; University Hospital of Ioannina, School of Medicine; Ioannina Greece
2. Cardiac Surgery Department; L'Institut Mutualiste Montsouris; Paris France
3. Cardiothoracic Surgery Department; School of Medicine, University Hospital of Patras; Patras Greece
4. Department of Anesthesiology; School of Medicine, University Hospital of Ioannina; Ioannina Greece