[Ventricular fibrillation after radiofrequency ablation of the atrioventricular node]

The authors report the case of a 77 year old patient who underwent radiofrequency ablation of the atrioventricular node for chronic. Invalidating atrial fibrillation, refractory to pharmacological therapy. A single chamber ventricular pacemaker was implanted one week before interruption of AV conduction. Eleven applications (7 on the right and 4 on the left side of the interventricular septum) were required for successful ablation. Four hours later, the patient developed episodes of non-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 of the spontaneous and paced QTc and JTc intervals). Eight days after ablation, the patient had an episode of ventricular fibrillation reduced by external DC shock. This arrhythmia was also preceded by changes in ventricular repolarisation. This case demonstrates the potential proarrhythmogenic effect of radiofrequency ablation of the AV node with changes in ventricular repolarisation which induces malignant ventricular arrhythmias. The authors suggest an appropriate preventive attitude. The progression in two distinct phases (immediate and late) imposes prolonged arrhythmia monitoring.