title: Chronic intermittent low-level transcutaneous electrical stimulation of auricular branch of vagus nerve improves left ventricular remodeling in conscious dogs with healed myocardial infarction.
abstract: BACKGROUND
  Vagus nerve stimulation attenuates left ventricular (LV) remodeling after myocardial infarction (MI). Our previous study found a noninvasive approach to deliver vagus nerve stimulation by transcutaneous electric stimulation of auricular branch of vagus nerve. So we hypothesize that chronic intermittent low-level tragus stimulation (LL-TS) could attenuate LV remodeling in conscious dogs with healed MI.
  
  
  RESULTS
  Thirty beagle dogs were randomly divided into 3 groups, MI group (left anterior descending artery and major diagonal branches ligation to introduce MI, n=10), LL-TS group (MI plus chronic intermittent LL-TS, n=10), and control group (sham surgery without stimulation, n=10). Tragus stimulation was delivered to bilateral tragus with ear-clips connected to a custom-made stimulator. The voltage slowing sinus rate was used as the threshold for setting LL-TS at 80% below that. LL-TS group was given 4 hours stimulation at 7-9 am and 4-6 pm on conscious dogs. At the end of 90-day follow-up, LL-TS group significantly reduced LA and LV dilatation, improved LV contractile and diastolic function, reduced infarct size by ≈50% compared with MI group. LL-TS treatment alleviated cardiac fibrosis and significantly decreased protein expression level of collagen I, collagen III, transforming growth factor β1, and matrix metallopeptidase 9 in LV tissues. The plasma level of high-specific C-reactive protein, norepinephrine, N-terminal pro-B-type-natriuretic peptide in LL-TS group was significantly lower than those in MI group from the 7th day to the end of follow-up.
  
  
  CONCLUSIONS
  Chronic intermittent low-level transcutaneous electric stimulation of auricular branch of vagus nerve can attenuate LV remodeling in conscious dogs with healed MI.
authors.affiliation: From the Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Wang
authors.affiliation: From the Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.
authors.forename: Lilei
authors.initials: L
authors.lastname: Yu
authors.affiliation: From the Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.
authors.forename: Songyun
authors.initials: S
authors.lastname: Wang
authors.affiliation: From the Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Huang
authors.affiliation: From the Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Liao
authors.affiliation: From the Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.
authors.forename: Gaowa
authors.initials: G
authors.lastname: Saren
authors.affiliation: From the Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.
authors.forename: Tuantuan
authors.initials: T
authors.lastname: Tan
authors.affiliation: From the Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China. whujianghong@163.com.
authors.forename: Hong
authors.initials: H
authors.lastname: Jiang
mesh_terms: D000818:Animals; D001341:Autonomic Nervous System / Q000503:physiopathology; D002097:C-Reactive Protein / Q000032:analysis; D004285:Dogs; D006439:Hemodynamics; D008297:Male; D009203:Myocardial Infarction / Q000503:physiopathology*; D020097:Natriuretic Peptide, Brain / Q000097:blood; D009638:Norepinephrine / Q000097:blood; D010446:Peptide Fragments / Q000097:blood; D004561:Transcutaneous Electric Nerve Stimulation; D055536:Vagus Nerve Stimulation / Q000379:methods*; D020257:Ventricular Remodeling
chemical_list: D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain; D002097:C-Reactive Protein; D009638:Norepinephrine
keywords: autonomic nervous system; left ventricular remodeling; myocardial infarction; vagus nerve stimulation