1. Cardiac Surgery, Lausanne University Hospital, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
2. Cardiac Surgery, Cardiocentro Ticino Institute, Lugano, Switzerland
3. Cardiac Surgery, Basel University Hospital, Basel, Switzerland
4. Cardiac Surgery, Cantonal Hospital, Lucerne, Switzerland
5. Cardio-Vascular Department, Geneva University Hospital, Geneva, Switzerland
6. Cardiac Surgery, University Hospital Zürich, Zürich, Switzerland