1. Department of Cardiothoracic Surgery, University Hospital Cologne, 50937 Cologne, Germany
2. Division of Thoracic and Cardiovascular Surgery, HELIOS Klinikum Siegburg, 53721 Siegburg, Germany
3. Faculty of Medicine, University Hospital of Cologne, Experimental Medicine, University of Cologne, 50937 Cologne, Germany
4. Department of Cardiothoracic Surgery, Otto-von-Guericke University Magdeburg, 39106 Magdeburg, Germany
5. Department of Cardiac Surgery, Kerckhoff-Clinic Bad Nauheim, Campus Kerckhoff, University of Giessen, 35392 Giessen, Germany