THE EFFECT OF RADIOFREQUENCY CATHETER ABLATION ON PERMANENT PACEMAKERS - AN EXPERIMENTAL-STUDY

Radiofrequency current is being investigated as an alternative to direct current shock for transcatheter abJation of cardiac arrhythmias. Permanent pacemakers are known to be susceptible to high frequency electromagnetic interference. This study was performed to examine the effects of Imnscatheter radiofrequency ablation on permanent pacemakers in a worst‐case scenario. Nineteen pulse generators representing 16 models from seven manufacturers were acutely implanted in 12 dogs to assess (heir function during and after ablation. Pulse generators were implanted subcutaneously in the neck and connected to a transvenous permanent pacing lead positioned in the right ventricular apex. A 6F quadri‐polar electrode catheter was positioned approximately 1 cm from the tip of the permanent pacing lead. Radiofrequency current from an electrosurgical unit was applied between the distal electrode of the catheter and a large diameter skin electrode placed below the left scapula. Three additional ablation sessions were performed with the catheter situated 4‐5 cm from the permanent pacing lead. Each ablation consisted of 35 W of radiofrequency power, delivered for up to 30 seconds. Twelve pulse generators were falsely inhibited during radiofrequency ablation while programmed to (he WI or DDD mode, nine of which continued to be inhibited while programmed to the VOO or DOO mode. Five pulse generators paced at abnormal rates, including three examples of one pulse generator model that displayed pacemaker runaway. Runaway was observed during eight ablations, resulting in two episodes of ventricular fibrillation. Eleven pulse generators reverted to noise mode behavior during ablation. Only three pulse generators were unaffected during ablation. No reprogramming or pacing system malfunctions were observed after cessation of radiofrequency current application or during ablations > 4 cm from the permanent lead. No changes in lead impedance, sensing, or capture threshold were observed. In conclusion, transcatheter radiofrequency ablation within close proximity of a permanent pacing lead may falsely inhibit implanted pulse generators, induce pacemaker runaway, or cause pulse generators to revert to noise mode behavior. Radiofrequency ablation performed in patients with permanent pacemakers requires careful monitoring as well as backup external pacing. A complete pacing system analysis should be performed following each ablation. Copyright © 1990, Wiley Blackwell. All rights reserved