title: A novel pacing maneuver to localize focal atrial tachycardia.
abstract: BACKGROUND
  Although focal atrial tachycardias cannot be entrained, we hypothesized that atrial overdrive pacing (AOP) can be an effective adjunct to localize the focus of these tachycardias at the site where the post-pacing interval (PPI) is closest to the tachycardia cycle length (TCL).
  
  
  METHODS
  Overdrive pacing was performed in nine patients during atrial tachycardia, and in a comparison group of 15 patients during sinus rhythm. Pacing at a rate slightly faster than atrial tachycardia in group 1 and sinus rhythm in group 2 was performed from five standardized sites in the right atrium and coronary sinus. The difference between the PPI and tachycardia or sinus cycle length (SCL) was recorded at each site. The tachycardia focus was then located and ablated in group 1, and the atrial site with earliest activation was mapped in group 2.
  
  
  RESULTS
  In both groups the PPI-TCL at the five pacing sites reflected the distance from the AT focus or sinus node. In group 1, PPI-TCL at the successful ablation site was 11 +/- 8 msec. In group 2, PPI-SCL at the site of earliest atrial activation was 131 +/- 37 msec (P < 0.001 for comparison). In groups 1 and 2, calculated values at the five pacing sites were proportional to the distance from the AT focus or sinus node, respectively.
  
  
  CONCLUSIONS
  The PPI-TCL after-AOP of focal atrial tachycardia has a direct relationship to proximity of the pacing site to the focus, and may be clinically useful in finding a successful ablation site.
authors.affiliation: Division of Cardiology, Department of Medicine, University of Western Ontario, London, Ontario, Canada.
authors.forename: Uwais
authors.initials: U
authors.lastname: Mohamed
authors.forename: Allan C
authors.initials: AC
authors.lastname: Skanes
authors.forename: Lorne J
authors.initials: LJ
authors.lastname: Gula
authors.forename: Peter
authors.initials: P
authors.lastname: Leong-Sit
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Krahn
authors.forename: Raymond
authors.initials: R
authors.lastname: Yee
authors.forename: Rajesh
authors.initials: R
authors.lastname: Subbiah
authors.forename: George J
authors.initials: GJ
authors.lastname: Klein
mesh_terms: D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004562:Electrocardiography; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D013612:Tachycardia, Ectopic Atrial / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome