1 Cardiac Surgery Unit, Cardiac-Thoracic-Vascular Department, San Gerardo Hospital, Monza, Italy.
2 Department of Anaesthesia and Critical Care Medicine, Cardiothoracic and Vascular Anaesthesia and Intensive Care, University Hospital, Pisa, Italy.
3 Cardiac Surgery Unit, Department of Medicine and Surgery, Parma General Hospital, University of Parma, Italy.
4 Cardiac Surgery Unit, Department of Medicine and Surgery, Parma General Hospital, University of Parma, Italy. Electronic address: francesco_formica@fastwebnet.it.