1 Department of Cardiovascular Surgery, University Heart Center, University Hospital Freiburg, Freiburg, Germany; Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany. Electronic address: julia.benk@uniklinik-freiburg.de.
2 Department of Cardiovascular Surgery, University Heart Center, University Hospital Freiburg, Freiburg, Germany; Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany.