title: The impact of pharmacologic sympathetic and parasympathetic blockade on atrial electrogram characteristics in patients with atrial fibrillation.
abstract: BACKGROUND
  Ablation of atrial autonomic inputs exerts antifibrillatory effects. However, because ablation destroys both myocardium and nerve cells, the effect of autonomic withdrawal alone remains unclear. We therefore examined the effects of pharmacologic autonomic blockade (PAB) on frequency and fractionation in patients with atrial fibrillation (AF).
  
  
  METHODS
  Esmolol and atropine were administered and electrograms were recorded simultaneously from both atria and the coronary sinus. In 17 patients, AF was recorded for 5 minutes and dominant frequency (DF) and continuous activity (CA) were compared before and during PAB.
  
  
  RESULTS
  Examination of the pooled data (537 sites, 17 patients) revealed a statistically significant decrease in mean DF (5.61–5.43Hz, P < 0.001) during PAB. Site-by-site analysis showed that 67% of sites slowed (0.45 ± 0.59 Hz), whereas 32% accelerated (0.49 ± 0.59Hz). Fractionation was reduced: median CA decreased from 31% to 26% (P < 0.001). In patient-by-patient analysis, mean DF/median CA decreased in 13 of 17 patients and increased in four. The spatial heterogeneity of DF decreased in nine of 17 patients (spatial coefficient of variation of DF at "nondriver sites" decreased by a mean of 2%).
  
  
  CONCLUSIONS
  PAB decreases DF and CA in the majority of sites. Given the complexity of interactions between atrial cells during AF, the effects of PAB on DF and fractionation are more heterogeneous than the effects of PAB on isolated cells.
authors: Department of Medicine, University of Vermont College of Medicine, Burlington, Vermont, USA.
authors: Nicole
authors: N
authors: Habel
authors: Joachim G
authors: JG
authors: Müller
authors: Pierre
authors: P
authors: Znojkiewicz
authors: Nathaniel
authors: N
authors: Thompson
authors: James
authors: J
authors: Calame
authors: Susan
authors: S
authors: Calame
authors: Arshia
authors: A
authors: Noori
authors: Annemarie
authors: A
authors: Gallo
authors: Daniel L
authors: DL
authors: Lustgarten
authors: Burton E
authors: BE
authors: Sobel
authors: Peter S
authors: PS
authors: Spector
mesh_terms: D058671:Adrenergic beta-1 Receptor Antagonists / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology*; D001285:Atropine / Q000627:therapeutic use; D004562:Electrocardiography / Q000187:drug effects*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods; D010276:Parasympatholytics / Q000627:therapeutic use*; D011412:Propanolamines / Q000627:therapeutic use; D013564:Sympathetic Nervous System / Q000187:drug effects; D013565:Sympatholytics / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D058671:Adrenergic beta-1 Receptor Antagonists; D010276:Parasympatholytics; D011412:Propanolamines; D013565:Sympatholytics; D001285:Atropine; C036604:esmolol