Intrinsic electrophysiologic properties of reentrant supraventricular tachycardia involving bypass tracts

Paolo Alboni, Nelly Paparella, Riccardo Cappato, Franco Baggioni, Salvatore Scarfo', Franco Percoco, Anna M. Tomasi

Research output: Contribution to journalArticlepeer-review


This study evaluates the effects of autonomic blockade (propranolol, 0.2 mg/kg, and atropine, 0.04 mg/kg) in 20 patients with paroxysmal supraventricular tachycardia (SVT). In 8 patients the SVT circuit involved a concealed atrioventricular bypass for retrograde conduction (group I) and in 12 a concealed atrio-His pathway (group II). Autonomic blockade did not significantly change atrial and ventricular refractory periods, whereas it prolonged atrioventricular nodal refractoriness without varying AH interval. The ventriculoatrial interval did not change in any patient. The H2A2 interval was unchanged in all but 2 group II patients. In both groups, the effective refractory period of the concealed bypass was prolonged by autonomic blockade. In the basal state, SVT was induced in all patients; after autonomic blockade, SVT was induced in 7 patients in group I (87%) and in 7 in group II (58%) (p <0.05). Cycle length of SVT was prolonged after autonomic blockade in 11 of these 14 patients. The variations were observed only in the anterograde conduction (Ae-H interval), whereas retrograde conduction (H-Ae interval) was unchanged in all patients. These data indicate that the autonomic system appears to facilitate induction of SVT in patients with concealed atrio-His bypass as well as shorten the cycle length of SVT in both groups of patients.

Original languageEnglish
Pages (from-to)266-272
Number of pages7
JournalThe American Journal of Cardiology
Issue number3
Publication statusPublished - Aug 1 1986

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine


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