Ancillary Effects of Dexmedetomidine Sedation After Cardiac Surgery

The investigator goal is to evaluate the effects of intraoperative and postoperative
dexmedetomidine sedation (versus placebo after cardiac surgery.

Inclusion Criteria:

1. 18-85 years old;

2. Scheduled for cardiac surgery with bypass (CABG, valve, or combined);

3. Able to provide a written informed consent;

4. Hemodynamically stable (heart rate>= 55).

Exclusion Criteria:

1. Sick sinus syndrome or Wolff-Parkinson-White syndrome

2. Atrio-ventricular block

3. Hypersensitivity or known allergy to dexmedetomidine

4. Hepatic disease, e.g. twice the normal level of liver enzymes

5. AF within 1 preoperative month;

6. Permanent pacemaker;

7. Use of amiodarone or dexmedetomidine within the last 30 days;

8. Patients with an ejection fraction under 30% or who had severe heart failure

9. Myocardial infarction in the previ¬ous 7 days;

10. Body mass index =< 40 (BMI= mass (kg) / height (m)2);

11. Those tak¬ing clonidine within last 48 hours.