Acute effects of radiofrequency ablation of atrial arrhythmias on implanted permanent pacing systems

We studied the safety of performing RF catheter ablation in patients with implanted permanent pacemakers by monitoring the function of implanted pacing systems before, during, and immediately after exposure to RF energy. Patients with implanted pacing systems may require RF ablation for treatment of a variety of tachyarrhythmias. High frequency electromagnetic fields, such as RF energy, may affect implanted pacing systems, causing temporary or permanent loss of output, undersensing, oversensing, asynchronous pacing, or reversion to "reset" (Recommended Replacement Time or Power On Reset) parameters. Thirty-five patients with implanted pacing systems (23 DDDR, 6 VVIR, 5 DDD, 1 VVI, 31 bipolar and 4 unipolar) underwent RF catheter ablation. Prior to ablation, each pacing system underwent measurements of pacing and sensing thresholds, telemetry of intracardiac electrograms and measurement of battery voltage and lead impedance(s). During ablation, pacemaker function was monitored by real-time telemetry, intracardiac electrograms, and surface ECG. Immediately after ablation, each pacing system was reevaluated. Telemetry during RF ablation revealed normal pacing and sensing in 14 (40%) of 35 patients. Refractory period extension with asynchronous pacing and noise mode reversion were seen in 16 (46%) of 35 patients. Rare under- and/or oversensing, reversion to reset parameters, and telemetry "lock up" with inhibition of pacing output was seen in a few patients. After ablation, there were no significant changes in atrial or ventricular pacing or sensing thresholds or measurements of atrial and ventricular lead impedances. We conclude that most permanent pacemakers are not adversely affected by exposure to RF energy during catheter ablation. A variety of pacemaker behaviors may be seen during RF ablation, and a thorough understanding of each pulse generator's potential response(s) to electromagnetic interference is important before undertaking catheter ablation in patients with permanent pacemakers. Careful reevaluation of the patient's pacing system following the procedure is mandatory.