title: Differential entrainment distinguishes atrioventricular nodal reentry tachycardia from atrioventricular reentrant tachycardia.
abstract: BACKGROUND
  Entrainment from the right ventricular (RV) apex and the base has been used to distinguish atrioventricular reentrant tachycardia (AVRT) from atrioventricular nodal reentry tachycardia (AVNRT). The difference in the entrainment response from the RV apex in comparison with the RV base has not been tested.
  
  
  METHODS
  Fifty-nine consecutive patients referred for ablation of supraventricular tachycardia (SVT) were included. Entrainment of SVT was performed from the RV apex and base, pacing at 10-40-ms faster than the tachycardia cycle length. SA interval was calculated from stimulus to earliest atrial electrogram. Ventricle to atrium (VA) interval was measured from the RV electrogram (apex and base) to the earliest atrial electrogram during tachycardia. The SA-VA interval from apex and base was measured and the difference between them was calculated.
  
  
  RESULTS
  Thirty-six AVNRT and 23 AVRT patients were enrolled. Mean age was 44 ± 12 years; 52% were male. The [SA-VA]apex-[SA-VA]base was demonstrable in 84.7% of patients and measured -9.4 ± 6.6 in AVNRT and 10 ± 11.3 in AVRT, P < 0.001. The difference was negative for all AVNRT cases and positive for all septal accessory pathways (APs).
  
  
  CONCLUSIONS
  The difference between entrainment from the apex and base is readily performed and is diagnostic for all AVNRTs and septal APs.
authors.affiliation: QE II Health Sciences Center, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Aamir H
authors.initials: AH
authors.lastname: Khan
authors.forename: Aliasghar
authors.initials: A
authors.lastname: Khadem
authors.forename: Magdy N
authors.initials: MN
authors.lastname: Basta
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Gardner
authors.forename: Ratika
authors.initials: R
authors.lastname: Parkash
authors.forename: Lorne J
authors.initials: LJ
authors.lastname: Gula
authors.forename: John L
authors.initials: JL
authors.lastname: Sapp
mesh_terms: D058606:Accessory Atrioventricular Bundle / Q000175:diagnosis / Q000503:physiopathology; D000328:Adult; D017115:Catheter Ablation; D003937:Diagnosis, Differential; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D013617:Tachycardia, Supraventricular / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery