1. Leipzig Heart Institute GmbH, Leipzig, Germany
2. German Society for Thoracic and Cardiovascular Surgery, Langenbeck-Virchow-Haus, Berlin, Germany
3. FOM Hochschule für Oekonomie and Management, Essen, Germany
4. Clinic for Cardiac and Vascular Surgery, University of Kiel, Kiel, Germany
5. Department of Cardiac and Thoracic Surgery, University of Cologne, Cologne, 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
8. Clinic for Cardiac, Thoracic and Vascular Surgery, Klinikum Braunschweig gGmbH, Braunschweig, Germany