1. Cardiac Surgery Unit, Parma University Hospital , Parma, Italy
2. Cardiac Surgery Unit, San Gerardo Hospital , Monza, Italy
3. Department of Critical Care Medicine and Division of Cardiac Surgery, Mazankowski, Alberta Heart Institute, University of Alberta , Edmonton, Canada
4. Cardiac Surgery Department, Hospital Universitario Central de Asturias , Oviedo, Spain
5. Department of Cardiothoracic Surgery, Erasmus University Medical Center , Rotterdam, Netherlands
6. Medical Library, University of Parma , Parma, Italy
7. Department of Medicine and Surgery, University of Parma , Parma, Italy