1. Department of Cardiac Surgery, University Hospital Halle (Saale), 06120 Halle (Saale), Germany
2. Department of Cardiac Surgery, Heidelberg University Hospital, 69120 Heidelberg, Germany
3. Department of Anaesthesiology, St. Josef Hospital, Ruhr-University Bochum, 44791 Bochum, Germany
4. Faculty Medical and Life Sciences, Furtwangen University, 78054 Villingen-Schwenningen, Germany