VENTRICULAR-FIBRILLATION AFTER RADIOFREQU ENCY ABLATION OF THE ATRIOVENTRICULAR NODE

The authors report the case of a 77 year old patient who underwent rad iofrequency ablation of the atrioventricular node for chronic, invalid ating atrial fibrillation, refractory to pharmacological therapy. A si ngle chamber ventricular pacemaker was implanted one week before inter ruption of AV conduction. Eleven applications (7 on the right and 4 on the left side of the interventricular septum) were required for succe ssful ablation. Four hours later, the patient developed episodes of no n-sustained polymorphic ventricular tachycardia and torsades de pointe . These arrhythmias were initiated by long cycle-short cycle sequences and preceded by changes of ventricular repolarisation (prolongation o f the spontaneous and paced QTc and JTc intervals). Eight days after a blation, the patient had an episode of ventricular fibrillation reduce d by external DC shock. This arrhythmia was also preceded by changes i n ventricular repolarisation. This case demonstrates the potential pro arrhytmogenic effect of radiofrequency ablation of the AV node with ch anges in ventricular repolarisation which induces malignant ventricula r arrhythmias. The authors suggest an appropriate preventive attitude. The progression in two distinct phases (immediate and late) imposes p rolonged arrhythmia monitoring.