1. Department of Surgery; Oulu University Hospital; Oulu Finland
2. Division of Cardiac Surgery; University of Verona Medical School; Verona Italy
3. Cardiac Surgery Unit; Varese University Hospital; Varese Italy
4. Department of Cardiothoracic and Respiratory Sciences; Second University of Naples; Naples Italy
5. Cardiac Surgery Unit; Poliambulanza Foundation Hospital; Brescia Italy
6. Department of Cardiac Surgery; Klinikum Nürnberg; Nuremberg Germany
7. Cardiac Surgery Unit; San Martino University Hospital; Genoa Italy