title: Analysis of atrioventricular nodal reentrant tachycardia with variable ventriculoatrial block: characteristics of the upper common pathway.
abstract: BACKGROUND
  The precise nature of the upper turnaround part of atrioventricular nodal reentrant tachycardia (AVNRT) is not entirely understood.
  
  
  METHODS
  In nine patients with AVNRT accompanied by variable ventriculoatrial (VA) conduction block, we examined the electrophysiologic characteristics of its upper common pathway.
  
  
  RESULTS
  Tachycardia was induced by atrial burst and/or extrastimulus followed by atrial-His jump, and the earliest atrial electrogram was observed at the His bundle site in all patients. Twelve incidents of VA block: Wenckebach VA block (n = 7), 2:1 VA block (n = 4), and intermittent (n = 1) were observed. In two of seven Wenckebach VA block, the retrograde earliest atrial activation site shifted from the His bundle site to coronary sinus ostium just before VA block. Prolongation of His-His interval occurred during VA block in 11 of 12 incidents. After isoproterenol administration, 1:1 VA conduction resumed in all patients. Catheter ablation at the right inferoparaseptum eliminated antegrade slow pathway conduction and rendered AVNRT noninducible in all patients.
  
  
  CONCLUSIONS
  Selective elimination of the slow pathway conduction at the inferoparaseptal right atrium may suggest that the subatrial tissue linking the retrograde fast and antegrade slow pathways forms the upper common pathway in AVNRT with VA block.
authors.affiliation: Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Morihisa
authors.forename: Hiroshige
authors.initials: H
authors.lastname: Yamabe
authors.forename: Takashi
authors.initials: T
authors.lastname: Uemura
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Koji
authors.initials: K
authors.lastname: Enomoto
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kawano
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Nagayoshi
authors.forename: Koichi
authors.initials: K
authors.lastname: Kaikita
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sumida
authors.forename: Seigo
authors.initials: S
authors.lastname: Sugiyama
authors.forename: Hisao
authors.initials: H
authors.lastname: Ogawa