1. Clinic for Cardiac Surgery, Heart Center Leipzig, University of Leipzig, Germany
2. German Society for Thoracic and Cardiovascular Surgery, Langenbeck-Virchow-Haus, Berlin, Germany
3. FOM Hochschule fuer Oekonomie & Management, Essen, Germany
4. Clinic for Cardiac and Vascular Surgery, University Kiel, Kiel, Germany
5. Department of Cardiothoracic Surgery, University of Cologne, Köln, Germany
6. Clinic for Cardiac Surgery, University of Bonn, Bonn, Germany
7. Clinic for Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Bad Oeynhausen, Germany