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.
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.
Otomo
Kiyoshi
K
Division of Cardiology, National Cardiovascular Center, Suita, Japan. k-otomo@fj8.so-net.ne.jp
Okamura
Hideo
H
Noda
Takashi
T
Satomi
Kazuhiro
K
Shimizu
Wataru
W
Suyama
Kazuhiro
K
Kurita
Takashi
T
Aihara
Naohiko
N
Kamakura
Shiro
S
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