Inclusion Criteria:  Subject must be 18 years old or older Subject must be willing to give written informed consent Subject must undergo or scheduled for non-emergent cardiac surgery, including coronary artery bypass grafting (CABG), non-infectious valve repair or replacement, atrial or septal defect repair, thoracic aortic replacement surgery, or any combination of these procedures  Exclusion Criteria:  Documented allergy to amiodarone or iodine History of atrial fibrillation or other heart conduction system abnormality History of cardiac maze, pulmonary vein isolation, or other procedure affecting the conduction system Scheduled cardiac maze, pulmonary vein isolation, or other procedure affecting the conduction system Low cardiac index or cardiogenic shock requiring pharmacologic or mechanical support History of pre-existing respiratory system disease requiring oxygen therapy prior to admission History of cirrhosis or other chronic liver diseases Pregnancy or breastfeeding mothers Prisoner status