Dexmedetomidine or Clonidine Infusion for Prevention of Delirium After Open Heart Surgery

Inclusion Criteria: Participants are eligible to be included in the study only if all of the following criteria apply: 1. Participant must be ≥70 years old at the time of signing the informed consent. 2. Participant must be accepted for cardiac surgery with cardiopulmonary bypass. The surgical procedures may constitute 1) coronary bypass grafting, 2) tricuspid, mitral, or aortic valve replacement or repair, 3) surgery on the ascending aorta, and 4) the combination any of these procedures. 3. Participant must be capable of giving signed informed consent. Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply: 4. Preoperative delirium 5. Known hypersensitivity to the active ingredient or components of the product 6. Bradycardia due to sick-sinus-syndrome, 2nd or 3rd degree AV-block (if not treated with pacemaker) or any other reason causing HR \<50 bpm at time of inclusion 7. Uncontrolled hypotension 8. Ischemic stroke or transitory ischemic attack the last month or critical peripheral ischemia 9. Acute coronary syndrome last 24 hours. Acute coronary syndrome is defined according to international guidelines 10. Left ventricular ejection fraction \< 40% 11. Severe renal impairment (estimated GFR \<20ml/min) or expected requirement for renal replacement therapy 12. Severe hepatic dysfunction (liver enzyme three times the upper limit of normal together with a serum albumin concentration below the normal reference limit) 13. Reduced peripheral autonomous activity (e.g. spinal cord injury) 14. Current use of tricyclic antidepressants, monoamine reuptake inhibitors or ciclosporin 15. Endocarditis or sepsis 16. Pheochromocytoma 17. Planned deep hypothermia and circulatory arrest 18. Emergency surgery, defined as less than 24 hours from admission to surgery 19. Previously included in this study 20. Not speaking or reading Norwegian 21. Any other condition as evaluated by the treating physician