Adverse effects of direct current cardioversion on cardiac pacemakers and electrodes Is external cardioversion contraindicated in patients with permanent pacing systems?

Use of pacing in sick sinus syndrome and recent developments in pacemaker therapy for intermittent atrial fibrillation raise the question of whether external electrical cardioversion should be used for termination of atrial fibrillation. This paper analyzes three cases of pacemaker and/or electrode dysfunction appearing after direct current (DC) cardioversion for termination of atrial fibrillation. Despite similar conditions during cardioversion in all cases, different dysfunctions reflecting damage to the pulse generator and/or a rise of the stimulation threshold in both, atrial and ventricular leads, have been observed. The possible mechanisms for these effects are discussed and recommendations for the management of cardioversion in patients with permanent pacemaker systems are given.