title: Oscillatory vagal maneuvers produce ventricular entrainment in patients with atrial fibrillation.
abstract: BACKGROUND
  Atrial fibrillation (AF) is the most common sustained dysrhythmia and appears to be an independent predictor of sudden cardiac death. The irregular ventricular rhythm contains both linear and non-linear patterns; however, it remains unclear whether vagally mediated effects are present within these patterns.
  
  
  OBJECTIVE
  We sought to determine if (1) power spectral analysis of heart rate can detect changes in vagal activity in patients with AF and (2) if the vagus modulates ventricular response during AF.
  
  
  METHODS
  Time and frequency domain parameters of heart rate variability (HRV) were calculated during forced vagal oscillations at 0.125 and 0.25 Hz imposed by neck suction and deep breathing in five AF patients.
  
  
  RESULTS
  There was a significant increase in SDRRI during deep breathing/neck suction combined compared to baseline (p=0.01) and deep breathing (p=0.03). Neck suction significantly increased SDRRI compared to baseline (p=0.03). Deep breathing/neck suction significantly increased spectral power compared to baseline (p=0.02) and deep breathing (p=0.03). Neck suction significantly increased spectral power compared to baseline (p=0.03). Deep breathing did not significantly increase HRV compared to baseline (p>0.20). In addition, SDRRI and spectral power were significantly correlated during deep breathing (r=0.91, p=0.03) and deep breathing/neck suction combined (r=0.92, p=0.02).
  
  
  CONCLUSIONS
  These data suggest that (1) power spectral analysis can detect vagal influences on heart rate in AF patients, and (2) oscillatory vagal maneuvers produce ventricular entrainment during AF.
authors.affiliation: Department of Integrative Physiology, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107-2699, USA. Christina.pacchia@unthsc.edu
authors.forename: Christina F
authors.initials: CF
authors.lastname: Pacchia
authors.forename: Geoff P
authors.initials: GP
authors.lastname: Kline
authors.forename: Mohamed H
authors.initials: MH
authors.lastname: Hamdan
authors.forename: Kari G
authors.initials: KG
authors.lastname: Clark
authors.forename: Michael G
authors.initials: MG
authors.lastname: Clark
authors.forename: Michael L
authors.initials: ML
authors.lastname: Smith
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D014630:Vagus Nerve / Q000502:physiology / Q000503:physiopathology