RESUMEN
We report a 59 year-old woman who had recurrent episodes of paroxystic supraventricular tachycardia despite pharmacologic therapy. A previous electrophysiological study (EPS) was done two years earlier without induction of any sustained arrhythmia. A new EPS was performed, during which atrial and ventricular programmed stimulation failed to induce tachycardia, and only by fast ventricular stimulation during intravenous isoproterenol infusion, a typical atrio ventricular nodal reentrant tachycardia (AVNRT) was induced. We successfully ablated the slow nodal pathway. After ablation the tachycardia was not inducible. We comment the occasional difficulties to induce AVNRT and the importance of a complete induction protocol to avoid false negative studies during the EPS.