title: Unique electrophysiologic characteristics of atrioventricular nodal reentrant tachycardia with different ventriculoatrial block patterns: effects of slow pathway ablation and insights into the location of the reentrant circuit.
abstract: BACKGROUND
  The electrophysiologic mechanisms of different ventriculoatrial (VA) block patterns during atrioventricular nodal reentrant tachycardia (AVNRT) are poorly understood.
  
  
  OBJECTIVE
  The purpose of this study was to characterize AVNRTs with different VA block patterns and to assess the effects of slow pathway ablation.
  
  
  METHODS
  Electrophysiologic data from six AVNRT patients with different VA block patterns were reviewed.
  
  
  RESULTS
  All AVNRTs were induced after a sudden AH "jump-up" with the earliest retrograde atrial activation at the right superoparaseptum. Different VA block patterns comprised Wenckebach His-atrial (HA) block (n = 4), 2:1 HA block (n = 1), and variable HA conduction times during fixed AVNRT cycle length (CL) (n = 1). Wenckebach HA block during AVNRT was preceded by gradual HA interval prolongation with fixed His-His (HH) interval and unchanged atrial activation sequence. AVNRT with 2:1 HA block was induced after slow pathway ablation for slow-slow AVNRT with 1:1 HA conduction, and earliest atrial activation shifted from right inferoparaseptum to superoparaseptum without change in AVNRT CL. The presence of a lower common pathway was suggested by a longer HA interval during ventricular pacing at AVNRT CL than during AVNRT (n = 5) or Wenckebach HA block during ventricular pacing at AVNRT CL (n = 1). In four patients, HA interval during ventricular pacing at AVNRT CL was unusually long (188 +/- 30 ms). Ablations at the right inferoparaseptum rendered AVNRT noninducible in 5 (83%) of 6 patients.
  
  
  CONCLUSIONS
  Most AVNRTs with different VA block patterns were amenable to classic slow pathway ablation. The reentrant circuit could be contained within a functionally protected region around the AV node and posterior nodal extensions, and different VA block patterns resulted from variable conduction at tissues extrinsic to the reentrant circuit.
authors.affiliation: Division of Cardiology, National Cardiovascular Center, Suita, Japan. k-otomo@fj8.so-net.ne.jp
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Otomo
authors.forename: Hideo
authors.initials: H
authors.lastname: Okamura
authors.forename: Takashi
authors.initials: T
authors.lastname: Noda
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Satomi
authors.forename: Wataru
authors.initials: W
authors.lastname: Shimizu
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Suyama
authors.forename: Takashi
authors.initials: T
authors.lastname: Kurita
authors.forename: Naohiko
authors.initials: N
authors.lastname: Aihara
authors.forename: Shiro
authors.initials: S
authors.lastname: Kamakura
mesh_terms: D000293:Adolescent; D000328:Adult; D016275:Atrial Function; D001283:Atrioventricular Node / Q000503:physiopathology / Q000601:surgery; D018780:Body Surface Potential Mapping; D002036:Bundle of His / Q000503:physiopathology / Q000601:surgery; D017115:Catheter Ablation; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D006327:Heart Block / Q000503:physiopathology* / Q000601:surgery*; D006801:Humans; D008875:Middle Aged; D012107:Research Design; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology* / Q000601:surgery*; D016896:Treatment Outcome