title: Impact of vagal nerve stimulation on left atrial structure and function in a canine high-rate pacing model.
abstract: BACKGROUND
  Cervical vagal nerve stimulation (VNS) can improve left ventricular dysfunction in the setting of heart failure (HF). However, little is known about the impact of VNS on left atrial (LA) function. The aim of this study was to compare LA mechanics and histology between control and VNS-treated animals during HF development.
  
  
  RESULTS
  Fifteen mongrel dogs were randomized into control (n=7) and VNS (n=8) groups. All dogs underwent 8 weeks of high-rate ventricular pacing (at 220 beats per minute for the first 4 weeks to develop HF and another 4 weeks at 180 beats per minute to maintain HF). LA contractile function (LA negative peak strain), conduit function (LA positive peak strain), and reservoir function (LA total strain) were measured from speckle tracking in 2 groups. At the end of the terminal study, the LA appendage was obtained. Baseline LA strains were comparable in the control and VNS-treated dogs. At 4 and 8 weeks of ventricular pacing, all LA strains were decreased and LA volumes were increased in the control group compared with the VNS group (P<0.05). Histological evaluation of the left atrium revealed that percent fibrosis was significantly lower in the VNS versus the control group (8±1% versus 13±1%; P<0.001). Finally, transmitral flow showed decreased atrial contribution to left ventricular filling in the control group (P<0.05).
  
  
  CONCLUSIONS
  VNS improved LA function and volumes and suppressed LA fibrosis in the canine high-rate ventricular pacing model. VNS is a novel and potentially useful therapy for improving LA function during HF.
authors.affiliation: Departments of Cardiovascular Medicine and Molecular Cardiology, Cleveland Clinic, OH; and New York Institute of Technology College of Osteopathic Medicine, Old Westbury.
authors.forename: Kenya
authors.initials: K
authors.lastname: Kusunose
authors.forename: Youhua
authors.initials: Y
authors.lastname: Zhang
authors.forename: Todor N
authors.initials: TN
authors.lastname: Mazgalev
authors.forename: David R
authors.initials: DR
authors.lastname: Van Wagoner
authors.forename: James D
authors.initials: JD
authors.lastname: Thomas
authors.forename: Zoran B
authors.initials: ZB
authors.lastname: Popović
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D006325:Heart Atria / Q000473:pathology* / Q000503:physiopathology; D006333:Heart Failure / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D006339:Heart Rate; D008297:Male; D016896:Treatment Outcome; D055536:Vagus Nerve Stimulation / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000503:physiopathology / Q000628:therapy*
keywords: atrial function, left; vagus nerve stimulation