title: Characterization of focal atrial tachycardia using high-density mapping.
abstract: OBJECTIVE
  The goal of this study was to characterize the origin of focal atrial tachycardias (AT).
  
  
  BACKGROUND
  Focal ATs originate from a small area and spread centrifugally; however, activation at the AT origin has not been characterized.
  
  
  METHODS
  Twenty patients with AT having failed prior ablation or occurring after atrial fibrillation ablation were studied. After excluding macro-re-entry, AT was mapped using a 20-pole catheter (five radiating spines; diameter 3.5 cm), performing vector mapping to identify the earliest activity followed by high-density mapping at the AT origin. Localized re-entry was considered if >85% of the tachycardia cycle length (CL) was observed within the mapping field and was confirmed by entrainment.
  
  
  RESULTS
  A total of 27 ATs were mapped to the pulmonary vein ostia (n = 5), and left (n = 16) and right atria (n = 6). A localized focus was evidenced at the site of origin in 19 ATs (70%), whereas in 8 (30%), localized re-entry was evidenced by 95.2 +/- 4.5% of the tachycardia CL recorded within the mapping field and entrainment showed a post-pacing interval <20 ms longer than tachycardia CL (6 of 6 tested). Localized re-entry had a shorter CL (p = 0.009), slowed conduction at its origin (fractionated potential 115 +/- 19 ms vs. 64 +/- 22 ms, representing 49 +/- 10% and 20 +/- 10% of tachycardia CL, respectively; p < 0.0001), and were more often contiguous with regions of electrical silence or conduction abnormalities (88% vs. 32%; p = 0.01). In addition, mapping documented varying degrees of intra-atrial conduction block, preferential conduction (n = 5), and rapid bursts of myocardial activity (n = 1). At 11 +/- 7 months, none have had recurrence of AT.
  
  
  CONCLUSIONS
  High-density multielectrode mapping can be used to perform vector mapping to localize complex AT. It provides novel insight into the mechanisms of focal AT, distinguishing focal AT from localized re-entry.
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque, Bordeaux, France. prash.sanders@heartrhythm.org
authors.forename: Prashanthan
authors.initials: P
authors.lastname: Sanders
authors.forename: Mélèze
authors.initials: M
authors.lastname: Hocini
authors.forename: Pierre
authors.initials: P
authors.lastname: Jaïs
authors.forename: Li-Fern
authors.initials: LF
authors.lastname: Hsu
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Martin
authors.initials: M
authors.lastname: Rotter
authors.forename: Christophe
authors.initials: C
authors.lastname: Scavée
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Pasquié
authors.forename: Fréderic
authors.initials: F
authors.lastname: Sacher
authors.forename: Thomas
authors.initials: T
authors.lastname: Rostock
authors.forename: Chrishan J
authors.initials: CJ
authors.lastname: Nalliah
authors.forename: Jacques
authors.initials: J
authors.lastname: Clémenty
authors.forename: Michel
authors.initials: M
authors.lastname: Haïssaguerre
mesh_terms: D000328:Adult; D006328:Cardiac Catheterization / Q000295:instrumentation; D017115:Catheter Ablation; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D005260:Female; D006325:Heart Atria / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013610:Tachycardia / Q000503:physiopathology* / Q000601:surgery