1. Department of Cardiovascular Surgery, Heart Centre Freiburg-Bad Krozingen, Faculty of Medicine, University of Freiburg, 79085 Freiburg, Germany
2. Division of Cardiac Surgery, University Hospital “Shefqet Ndroqi”, University of Medicine, 1005 Tirana, Albania
3. Department of Cardiac Surgery, University Hospital Bern, University of Bern, 3012 Bern, Switzerland
4. Department of Cardiology and Angiology II, University Heart Centre Freiburg-Bad Krozingen, 79189 Bad Krozingen, Germany