title: Influence of wavefront dynamics on transmembrane potential characteristics during atrial fibrillation.
abstract: BACKGROUND
  Although computerized mapping studies have demonstrated the presence of multiple wavelets during atrial fibrillation (AF) and that action potential amplitude and duration in AF vary significantly from beat to beat, no study has correlated the single cell action potential changes with the patterns of activation during AF.
  
  
  RESULTS
  We studied wavefront dynamics and single cell transmembrane potential (TMP) characteristics in 12 isolated perfused canine right atria. The endocardial surface was mapped using 477 bipolar electrodes while TMP was recorded with a standard glass microelectrode from an epicardial cell. AF was induced in the presence of acetylcholine. Successful simultaneous TMP recordings and activation maps were made during six episodes of AF and for a total of 141 activations. Large variations of TMP amplitude and duration were observed frequently; 34% of them have a low amplitude (<50% of the amplitude recorded during pacing). Low-amplitude potentials were recorded when the impaled cell was (1) in an area of random reentry (67%, n = 36); (2) within 3.2 mm of the core of organized functional reentry (22%, n = 12); (3) in the middle of two merging wavefronts (9%, n = 5); and (4) at the point of spontaneous wavebreak (2%, n = 1).
  
  
  CONCLUSIONS
  Large variations of TMP are observed frequently during in vitro AF. Low-amplitude TMPs are associated with specific patterns of AF activation wavefronts.
authors.affiliation: Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California 90048, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Athill
authors.forename: T J
authors.initials: TJ
authors.lastname: Wu
authors.forename: M
authors.initials: M
authors.lastname: Yashima
authors.forename: Y H
authors.initials: YH
authors.lastname: Kim
authors.forename: J N
authors.initials: JN
authors.lastname: Weiss
authors.forename: H L
authors.initials: HL
authors.lastname: Huang
authors.forename: H S
authors.initials: HS
authors.lastname: Karagueuzian
authors.forename: P S
authors.initials: PS
authors.lastname: Chen
mesh_terms: D000200:Action Potentials; D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial; D004285:Dogs; D004594:Electrophysiology; D066298:In Vitro Techniques; D008564:Membrane Potentials; D011930:Reaction Time