1 Department of Thoracic and Cardiovascular Surgery, University Hospital Tuebingen, Calwerstr. 7/1, 72076 Tuebingen, Germany. Electronic address: meltem.avci-adali@uni-tuebingen.de.
2 Head of Department, Department of Biomedical Engineering and W.J. Kolff Institute for Biomedical Engineering and Materials Science, University Medical Center Groningen/University of Groningen, Ant. Deusinglaan 1, 9713 AV Groningen, The Netherlands. Electronic address: h.a.santos@umcg.nl.