1. Department of Cardiac Surgery; University Hospital Halle (Saale); Halle Saale Germany
2. Department of Cardiovascular Surgery; University Heart Center Hamburg; Hamburg Germany
3. Department of Cardiothoracic Surgery; King's College Hospital London; London United Kingdom
4. Department of Cardiac Surgery; Asklepios Klinik St. Georg; Hamburg Germany
5. Department of Cardiac Surgery; University Heart Center Dresden; Dresden Germany
6. Department of Cardiac Surgery; Center of Cardiovascular Diseases Rotenburg a. d. Fulda; Rotenburg Germany
7. Department of Cardiovascular Surgery; Robert-Bosch-Krankenhaus; Stuttgart Germany
8. Department of Cardiac Surgery; Heart Center Leipzig, University of Leipzig; Leipzig Germany
9. Department of Cardiovascular Surgery; Klinikum München Bogenhausen GmbH; Munich Germany