1. Faculty of Medicine, Friedrich-Schiller-University of Jena, Erlanger Allee 101, Jena, Germany
2. Department of Cardiology, Catholic Hospital Koblenz-Marienhof, Koblenz, Germany
3. Department of Cardiothoracic Surgery, Kasr-El-Aini School of Medicine, Cairo University, Egypt
4. Department of Medical Statistics, Computer Sciences and Documentation, Friedrich-Schiller-University of Jena, Jena, Germany
5. Department of Anesthesiology and Intensive Care Medicine, Friedrich-Schiller-University of Jena, Jena, Germany
6. Department of Cardiothoracic Surgery, University of Cologne, Cologne, Germany
7. Cardiothoracic Surgery, CardioClinic, Cologne, NRW, Germany