title: Reversing the direction of paced ventricular and atrial wavefronts reveals an oblique course in accessory AV pathways and improves localization for catheter ablation.
abstract: BACKGROUND
  The purpose of this study was to determine how often accessory atrioventricular (AV) pathways (AP) cross the AV groove obliquely. With an oblique course, the local ventriculoatrial (VA) interval at the site of earliest atrial activation (local-VA) and the local-AV interval at the site of earliest ventricular activation (local-AV) should vary by reversing the direction of the paced ventricular and atrial wavefronts, respectively.
  
  
  RESULTS
  One hundred fourteen patients with a single AP were studied. Two ventricular and two atrial pacing sites on opposite sides of the AP were selected to reverse the direction of the ventricular and atrial wavefronts along the annulus. Reversing the ventricular wavefront increased local-VA by >/=15 ms in 91 of 106 (91%) patients. With the shorter local-VA, the ventricular potential overlapped the atrial potential along a 17.2+/-8.5-mm length of the annulus. No overlap occurred with the opposite wavefront. Reversing the atrial wavefront increased local-AV by >/=15 ms in 32 of 44 (73%) patients. With the shorter local-AV, the atrial potential overlapped the ventricular potential along an 11.9+/-8.9-mm length of the annulus. No overlap occurred with the opposite wavefront. Mapping during longer local-VA or local-AV identified an AP potential in 102 of 114 (89%) patients. Catheter ablation eliminated AP conduction in all 111 patients attempted (median, 1 radiofrequency application in 99 patients with an AP potential versus 4.5 applications without an AP potential).
  
  
  CONCLUSIONS
  Reversing the direction of the paced ventricular or atrial wavefront reveals an oblique course in most APs and facilitates localization of the AP potential for catheter ablation.
authors.affiliation: Cardiac Arrhythmia Research Institute, University of Oklahoma, Oklahoma City 73104, USA.
authors.forename: K
authors.initials: K
authors.lastname: Otomo
authors.forename: M D
authors.initials: MD
authors.lastname: Gonzalez
authors.forename: K J
authors.initials: KJ
authors.lastname: Beckman
authors.forename: H
authors.initials: H
authors.lastname: Nakagawa
authors.forename: A E
authors.initials: AE
authors.lastname: Becker
authors.forename: N
authors.initials: N
authors.lastname: Shah
authors.forename: K
authors.initials: K
authors.lastname: Matsudaira
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.forename: R
authors.initials: R
authors.lastname: Lazzara
authors.forename: W M
authors.initials: WM
authors.lastname: Jackman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001283:Atrioventricular Node / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation; D002648:Child; D002675:Child, Preschool; D005260:Female; D006325:Heart Atria / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology*; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged