1. Clinic of Cardiology, St. Olavs University Hospital, Trondheim, Norway
2. Department of Circulation and Medical Imaging, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Box 8905, 7491 Trondheim, Norway
3. Department of Medicine, Levanger Hospital, Nord-Trøndelag Hospital Trust, Levanger, Norway
4. Clinic of Cardiothoracic Surgery, St. Olavs University Hospital, Trondheim, Norway
5. Clinic of Anaesthesia and Intensive Care, St. Olavs University Hospital, Trondheim, Norway