1. Department of Cardiothoracic Surgery, University Hospital Birmingham NHS Foundation Trust, Birmingham, UK
2. Department of Cardiac and Vascular Surgery, Robert Bosch Hospital, Stuttgart, Germany
3. Department of Cardiac Surgery, Sant’Orsola-Malpighi Hospital, Bologna, Italy
4. Department of Cardiovascular Surgery, Hospital Hietzing, Vienna, Austria
5. Department of Cardiac Surgery, Leipzig Heart Center, University of Leipzig, Leipzig, Germany
6. Tampere University Hospital Heart Center, Tampere, Finland
7. Department of Thoracic and Cardiovascular Surgery, West German Heart Centre Essen, University Hospital Essen, Essen, Germany