1. Department of Cardiovascular Surgery, Heart Centre Freiburg University , Hugstetter Str. 55, 79106 Freiburg , Germany
2. Faculty of Medicine, University of Freiburg , Hugstetter Str. 55, 79106 Freiburg , Germany
3. Institute for Surgical Pathology , Hugstetter Str. 55, 79106 Freiburg , Germany