Comparison of Oxygen Interventions and Defibrillator Efficiency

Background: Cardiac arrhythmias can be terminated by electrical current applied by an external defibrillator. This treatment, named cardioversion, has been used for decades in the treatment of atrial fibrillation. Several kinds of defibrillators exist, though the relative efficacy and safety of these defibrillators is not clear. During cardioversion, oxygen is being administered, and it has been a long-held belief that oxygen is always beneficial for the patient. This is now being challenged by recent studies suggesting excessive oxygenation to be potentially dangerous for the patients. Objective: 1. To compare the efficiency and safety of two different defibrillators 2. To investigate the effects of excessive oxygen on injury of the heart following cardioversion. Experimental design: Patients will be recruited at the outpatient clinic at the Department of Cardiology, Regional Hospital of Randers, Denmark as a part of the pre-cardioversion check. Patients will be randomized to cardioversion using one of two defibrillators and randomized to treatment with room air or 100% oxygen. The cardiac condition will be measured by blood samples before cardioversion, 4 hours after cardioversion and 3 months after cardioversion. Heart rhythm will be measured by ECG before cardioversion, 1 minute-, 30 minutes- and 4 hours after cardioversion.