RESUMO
AIM: In some patients with clinical paroxysmal supraventricular tachycardia (PSVT), who are candidates for radiofrequency (RF) catheter ablation, attempts for the induction of arrhythmia during the electrophysiological study (EPS) fail despite different stimulation protocols even during the isoproterenol infusion and atropine injection. The presence of an atrial-His interval (AH) jump during decremental pre-mature atrial stimulation is the only clue for slow pathway ablation in these patients; in occasional patients, however, the AH jump is an accidental finding and the real arrhythmia is not atrioventricularnodal reentrant tachycardia (AVNRT). We aimed to introduce a new method for the induction of AVNRT in these patients. METHODS AND RESULTS: Ten patients (50% male, mean age=44.40 ± 12.80 years) with clinical PSVT who were referred to our department for the EPS and RF catheter ablation were selected. These patients had documented clinical PSVT with non-inducible arrhythmia during the EPS with different stimulation protocols even during the isoproterenol infusion and atropine injection but they only showed an AH jump. To induce AVNRT, low-watt (15-20), low-temperature (40-45°C) RF currents were delivered into the slow pathway area for a maximum of 40 s. Atrioventricularnodal reentrant tachycardia was inducible in five cases (50%, three male, mean age=45.80 ± 9.65 years). Induction of AVNRT occurred either during the RF current application after the occurrence of junctional ectopic beats or after another stimulation protocol. CONCLUSION: A low-watt, low-temperature RF current application into the slow pathway area can be a provocative method for the induction of AVNRT probably by AV-junction warming and conduction-velocity augmentation.