title: Entrainment for distinguishing atypical atrioventricular node reentrant tachycardia from atrioventricular reentrant tachycardia over septal accessory pathways with long-RP [corrected] tachycardia.
abstract: BACKGROUND
  The response to right ventricular (RV) entrainment is useful to distinguish atypical AV node reentrant tachycardia from AV reentrant tachycardia using a septal accessory pathway. Whether entrainment can differentiate between AV node reentrant tachycardia and AV reentrant tachycardia in patients with long-RP tachycardia has not been systematically validated.
  
  
  RESULTS
  Twenty-four patients with concealed septal accessory pathways who had an electrophysiology study between January 1, 2000, and January 1, 2010, were included (age, 38 ± 17 years; men, 17). Entrainment was performed from the RV apex pacing at cycle length 20 to 40 ms shorter than tachycardia cycle length (TCL). The mean TCL was 390 ± 80 ms, the mean AH interval during tachycardia was 151 ± 57 ms, and the mean ventriculoatrial (VA) time was 182 ± 103 ms. Twelve patients had typical accessory pathways (VA/TCL <40%), and 12 had slowly conducting accessory pathways (VA/TCL ≥ 40%). In all patients with typical accessory pathways, the postpacing interval minus the TCL (PPI-TCL) was <115 ms and the difference in the VA interval during pacing and tachycardia (StimA-VA) was <85 ms. On the other hand, in 6 of the 12 patients in the slowly conducting group, the PPI-TCL was >115 ms, and the StimA-VA was > 85 ms.
  
  
  CONCLUSIONS
  Slowly conducting accessory pathways frequently yield RV entrainment criteria traditionally attributable to AV node reentry. Distinguishing AV node reentry from AV reentry in patients with long-RP tachycardia requires other criteria.
authors.affiliation: Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada. Matthew.bennett@vch.ca
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Bennett
authors.forename: Peter
authors.initials: P
authors.lastname: Leong-Sit
authors.forename: Lorne J
authors.initials: LJ
authors.lastname: Gula
authors.forename: Allan C
authors.initials: AC
authors.lastname: Skanes
authors.forename: Raymond
authors.initials: R
authors.lastname: Yee
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Krahn
authors.forename: Ellaina C
authors.initials: EC
authors.lastname: Hogg
authors.forename: Elaina C
authors.initials: EC
authors.lastname: Hogg
authors.forename: George J
authors.initials: GJ
authors.lastname: Klein
mesh_terms: D058606:Accessory Atrioventricular Bundle / Q000503:physiopathology*; D000328:Adult; D001283:Atrioventricular Node / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial / Q000379:methods; D003937:Diagnosis, Differential; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D020665:Septum of Brain / Q000503:physiopathology*; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000145:classification* / Q000175:diagnosis* / Q000503:physiopathology; D017180:Tachycardia, Ventricular / Q000503:physiopathology*; D013997:Time Factors