1. Department of Surgical Research and Clinic for Cardiovascular Surgery, University Hospital and University of ZürichRaemistrasse 100, CH 8091 Zürich, Switzerland
2. Department of Medical Physics and Biophysics, Charité UniversityInvalidenstrasse 42, 10098 Berlin, Germany
3. Department of Biomedical Engineering, University of Technology Eindhoven5600 MB Eindhoven, The Netherlands