PACEMAKER MALFUNCTIONS DURING RADIOFREQUE NCY CATHETER ABLATION OF THE AV NODE DESPITE VOO STIMULATION

We present 10 patients undergoing radiofrequency catheter ablation of the AV node. In all cases, the pacemaker had been implanted for differ ent reasons prior to the ablation procedure. All pacemakers exhibited transient Ventricular exit block immediately after the onset of radiof requency current application which could not be prevented despite devi ce reprogramming to asynchrone stimulation (V00). In the last one (Met a II pacemaker), ventricular exit block occurred immediately after the onset of radiofrerquency catheter ablation lasting for several minute s. In the remaining case, an implanted Medtronic pacemaker (Elite 7076 ) showed intermittent ventricular exit block and the induction of a ra pid atrial burst stimulation No evidence for pacemaker malfunction was observed in all the above mentioned pacemakers immediately after the ablation procedure and during regular follow-up. It seems that unexpec ted pacemaker malfunction due to radiofrequency current occurring desp ite reprogramming to V00 mode can be related to certain types of pacem akers. Our observations suggest that in patients with prior pacemaker implantation undergoing radiofrequency ablation procedure, an addition al pacing lead should be placed in the right ventricle in order to avo id an asystolic complication due to radiofrequency current-mediated ma lfunction of the pacemaker. Manufacturers of the pacemakers should pay more attention to this problem.