1. Cardiology, Department of Medicine, Faculty of Science, University of Fribourg, Chemin du Musée 5, 1700 Fribourg, Switzerland
2. Clinic for Cardiovascular Surgery, Inselspital Berne, Berne University Hospital and University of Berne, Switzerland
3. Empa, Swiss Federal Laboratories for Material Science and Technology, 9014 St. Gallen, Switzerland