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