title: Superior type of atypical AV nodal reentrant tachycardia: incidence, characteristics, and effect of slow pathway ablation.
abstract: BACKGROUND
  Atypical atrioventricular (AV) nodal reentrant tachycardias (AVNRT) usually exhibit the earliest retrograde atrial activation (ERAA) at the right inferoseptum (Rt-IS) or proximal coronary sinus (PCS). The purpose of this study was to characterize atypical AVNRT with the ERAA at the right superoseptum (Rt-SS).
  
  
  METHODS
  Seventy-three atypical AVNRTs induced in 63 cases were classified into the superior type with the ERAA at the Rt-SS and inferior type with the ERAA at the Rt-IS or PCS.
  
  
  RESULTS
  There were nine superior (12%) and 64 inferior types of atypical AVNRT (88%) in seven and 56 cases, respectively. The superior type exhibited a short atrial-His interval during the tachycardia (166 +/- 41 ms), long His-atrial interval during the tachycardia (H-At:156 +/- 38 ms), and ventricular pacing at the tachycardia cycle length (TCL) (H-Ap:201 +/- 36 ms), and evidence for a lower common pathway, including second-degree AV block (four tachycardias) and an H-Ap being longer than the H-At (nine tachycardias). The TCL was shorter in the superior type than in the inferior type (322 +/- 35 vs 404 +/- 110 ms; P < 0.02). In the inferior type, all tachycardias were eliminated after the ablation at the Rt-IS (44 tachycardias) or PCS (20 tachycardias) where an ERAA was recorded. In the superior type, ablation at the Rt-IS was ineffective; however, ablation at the right midseptum eliminated seven (78%) of the nine tachycardias.
  
  
  CONCLUSIONS
  The tachycardia circuit of the superior type might have deviated to a more superior part of Koch's triangle than that of the inferior type.
authors.affiliation: Division of Cardiology, Cardiovascular Center, Tsuchiura Kyodo Hospital, Tsuchiura, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Otomo
authors.forename: Yasutoshi
authors.initials: Y
authors.lastname: Nagata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Taniguchi
authors.forename: Kikuya
authors.initials: K
authors.lastname: Uno
authors.forename: Hideomi
authors.initials: H
authors.lastname: Fujiwara
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Iesaka
mesh_terms: D017115:Catheter Ablation / Q000706:statistics & numerical data*; D005260:Female; D006329:Heart Conduction System / Q000601:surgery*; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000175:diagnosis / Q000453:epidemiology* / Q000601:surgery*; D016896:Treatment Outcome