1. Department of Cardiac Surgery, Heidelberg University, Heidelberg, Germany
2. Department of Cardiac Surgery, Helios Klinik, Karlsruhe, Germany
3. Department of Cardiac Surgery, Oldenburg University Hospital, Oldenburg, Germany
4. Department of Thoracic and Cardiovascular Surgery, University Hospital Tübingen, Tübingen, Germany
5. Department of Cardiovascular Surgery, University Hospital Freiburg, Freiburg, Germany
6. Department of Vascular Surgery, Vascular Center Berlin-Brandenburg, Academic Hospital Hubertus, Berlin, Germany
7. Department of Cardiovascular Surgery, University Hospital Giessen, Giessen, Germany