In our letter, we only noted that the radiofrequency current interfered with the function of the pacemaker but that there was no damage the pacemaker itself.1Actually, we described this effect as “falsely inhibited,” which was very similar to what was first described by Chin et al.  2Chin et al.  noted that intracardiac radiofrequency current may produce a number of potentially serious pacing systems malfunctions. When such ablation was performed in close proximity to a pacing lead, false inhibition was observed, even when devices were programmed to the asynchronous mode. Several devices paced at abnormal rates during current flow, producing extremely rapid pacemaker runaway. Some pacers reverted to a noise mode of operation during the ablation procedures. Despite these effects, none of the devices was spuriously reprogrammed by the ablation, with the exception of revision to reset mode. Nor were any of the pulse generators permanently damaged. In our case, the situation was similar and that is why we described the device as “falsely inhibited” rather than “true inhibition” in our first submission. However, some reviewers had different opinions and were uncomfortable with the term “falsely inhibited.” They insisted that the generator is either inhibited or it is not. Finally we omitted the word “falsely.”

Second, a statement is needed regarding the placement of the current returns pads, which should be as close as possible to the radiofrequency ablation delivery electrodes to prevent or minimize radiofrequency ablation current travel across the generator and lead systems. In this case, two grounding pads were applied to the posterior aspects of the patient's thighs as close as possible to the ablation electrodes. This comment was deleted during the revision of the work.

Third, complete supra-Hisian Atrio-ventricular block was diagnosed by a cardiologist via  a formal electrophysiological study.

* Chang Gung Memorial Hospital at Keelung, Keelung, Taiwan, ROC.

Tong NY, Ru HJ, Ling HY, Cheung YC, Meng LW, Chung PC: Extracardiac radiofrequency ablation interferes with pacemaker function but does not damage the device. Anesthesiology 2004; 100:1041
Chin MC, Rosenqvist M, Lee MA, Griffin JC, Langberg JJ: The effect of radiofrequency catheter ablation on permanent pacemakers: An experimental study. PACE 1990; 13:23–9