title: Frequency gradients during two different forms of fibrillation in the canine atria.
abstract: BACKGROUND
  Atrial fibrillation (AF) is thought to be sustained by multiple reentrant wavelets or firing foci.
  
  
  OBJECTIVE
  The aim of this study was to compare the spectral domain characteristics in the left atrium (LA) and right atrium (RA) in two different models of AF.
  
  
  METHODS
  Rectangular 8 x 14 electrode arrays were placed on the LA and RA of 14 anesthetized dogs. AF episodes were induced with burst pacing and aconitine in each dog. For each model, AF was induced from the RA in six dogs and from the LA in six dogs. Dominant frequencies (DFs) were obtained using the fast Fourier transform of the unipolar recordings obtained from each electrode of the array. Standard deviation (SD) was used to compute the frequency dispersion within an atrium. Regularity of the signal was quantified using an organization index (OI).
  
  
  RESULTS
  DFs were largest in the atrium where aconitine was applied. Aconitine AF had larger gradients than burst-pacing AF (5.0 +/- 4.5 vs. 0.9 +/- 1.0 Hz: P <.006). Aconitine AF when compared with burst-pacing AF had greater absolute LA-RA differences in the SD of DFs (2.3 +/- 1.9 vs. 0.2 +/- 0.2 Hz; P <.001) and in OI (0.11 +/- 0.07 vs. 0.06 +/- 0.07; P <.07).
  
  
  CONCLUSIONS
  Differences in frequency gradients and organization were observed during AF induced by burst pacing and aconitine. This suggests that different mechanisms of AF are possible and may be identified with frequency domain analysis.
authors: Feinberg Cardiovascular Research Institute and Department of Medicine, Division of Cardiology, Northwestern University, Northwestern Memorial Hospital, 251 East Huron, Chicago, IL 60611, USA.
authors: Joseph S
authors: JS
authors: Ulphani
authors: Jason
authors: J
authors: Ng
authors: Rahul
authors: R
authors: Aggarwal
authors: Jack H
authors: JH
authors: Cain
authors: David
authors: D
authors: Gordon
authors: Eric
authors: E
authors: Yang
authors: Alexander R
authors: AR
authors: Morris
authors: Rishi
authors: R
authors: Arora
authors: Jeffrey J
authors: JJ
authors: Goldberger
authors: Alan H
authors: AH
authors: Kadish
mesh_terms: D000157:Aconitine; D000818:Animals; D001281:Atrial Fibrillation / Q000139:chemically induced / Q000503:physiopathology*; D016279:Atrial Function, Left / Q000187:drug effects / Q000502:physiology; D016280:Atrial Function, Right / Q000187:drug effects / Q000502:physiology; D002304:Cardiac Pacing, Artificial; D004195:Disease Models, Animal; D004285:Dogs; D004562:Electrocardiography; D005583:Fourier Analysis; D006325:Heart Atria / Q000187:drug effects / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000139:chemically induced / Q000503:physiopathology*
chemical_list: D000157:Aconitine