ACUTE EFFECTS OF RADIOFREQUENCY ABLATION OF ATRIAL ARRHYTHMIAS ON IMPLANTED PERMANENT PACING SYSTEMS

We studied the safety of performing RF catheter ablation in patients w ith implanted permanent pacemakers by monitoring the function of impla nted pacing systems before, during, and immediately after exposure to RF energy. Patients with implanted pacing systems may require RF ablat ion for treatment of a variety of tachyarrhythmias, High frequency ele ctromagnetic fields, such as RF energy, may affect implanted pacing sy stems, causing temporary or permanent loss of output, undersensing, ov ersensing, 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 bipol ar and 4 unipolar) underwent RF catheter ablation. Prior to ablation, each pacing system underwent measurements of pacing and sensing thresh olds, telemetry of intracardiac electrograms and measurement of batter y voltage and lead impedance(s). During ablation, pacemaker function w as monitored by real-time telemetry, intracardiac electrograms, and su rface EGG. Immediately after ablation, each pacing system was reevalua ted. Telemetry during RF ablation revealed normal pacing and sensing i n 14 (40%) of 35 patients. Refractory period extension with asynchrono us pacing and noise mode reversion were seen in 16 (46%) of 35 patient s. Rare under- and/or oversensing, reversion to reset parameters, and telemetry ''lock up'' with inhibition of pacing output was seen in a f ew patients. After ablation, there were no significant changes in atri al or ventricular pacing or sensing thresholds or measurements of atri al and ventricular lead impedances. We conclude that most permanent pa cemakers are not adversely affected by exposure to RF energy during ca theter ablation. A variety of pacemaker behaviors may be seen during R F ablation, and a thorough understanding of each pulse generator's pot ential 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 proc edure is mandatory.