1. Department of Health and Caring Sciences, Western Norway University of Applied Sciences , P.O box 7030, 5020 Bergen , Norway
2. Department of Health and Functioning, Western Norway University of Applied Sciences , Bergen , Norway
3. Department of Cardiothoracic Surgery, Haukeland University Hospital , Bergen , Norway
4. Department of Clinical Science, Faculty of Medicine, University of Bergen , Bergen , Norway
5. Institute of Clinical Medicine, Faculty of Medicine, University of Oslo , Oslo , Norway
6. Department of Cardiothoracic Surgery, Oslo University Hospital , Oslo , Norway
7. Norwegian Register for Cardiac Surgery , Oslo , Norway
8. Department of Anaesthesia and Intensive Care, Haukeland University Hospital , Bergen , Norway
9. Department of Clinical Medicine, University of Bergen , Norway
10. Faculty of Health Sciences, VID Specialized University , Bergen , Norway