['Ventricular preexcitation syndromes are classically more common in the pediatric age group than in adults, and a latent Kent bundle may explain most cases of paroxysmal junctional tachycardia (PJT). These data stem from the results of intracardiac electrophysiologic testing, which is performed only in those patients at the most severe end of the symptom spectrum. The recent introduction of transesophageal testing has expanded the indications of electrophysiologic testing for PJT. This technique was used to determine the mechanism of PJT in 23 adolescents aged 11 to 9 years (mean age, 16 +/- 3 years) with paroxysmal palpitations, accompanied in seven cases with dizziness or syncope. Only four patients had documented PJT. The basal ECG was normal, and exercise testing showed no evidence of preexcitation. Pacing at increasing rates and programmed stimulation with one then two extra-stimuli was used and repeated, if needed, under infusion of 20 to 30 micrograms of isoproterenol.', "PJT was induced in 21 patients (91%), under basal conditions in 13 and under isoproterenol in eight. Neither of the two patients with a negative test had documented tachycardia. Based on classic criteria (position of A relative to V1, effect of a bundle branch block, and shape of A in D1 and V1), the mechanism of the PJT was shown to be nodal reentry in 17 cases (81%) and reentry into a latent left-sided Kent's bundle in four cases. Atrial fibrillation was also induced in two of the patients with nodal reentry. In six of the patients with dizziness or syncope associated with palpitations, these symptoms were due to nodal reentry."] Is [ Junctional tachycardia in adolescents : nodal reentry the most frequent cause ]?