title: Low-level carotid baroreceptor stimulation suppresses ventricular arrhythmias during acute ischemia.
abstract: BACKGROUND
  The autonomic imbalance during acute ischemia is involved in the occurrence of life-threatening arrhythmias.
  
  
  OBJECTIVE
  To investigate the effect of autonomic nervous system (ANS) modulation by low-level carotid baroreceptor stimulation (LL-CBS) on ventricular ischemia arrhythmias.
  
  
  METHODS
  Anesthetized dogs were received either sham treatment (SHAM group, n = 10) or LL-CBS treatment (LL-CBS group, n = 10). The voltage lowering the blood pressure was used as the threshold for setting LL-CBS at 80% below the threshold. Treatment started 1 hour before left anterior descending coronary (LAD) occlusion, and continued until the end of experience. Ventricular effective refractory periods (ERP), monophasic action potential duration at 90% (APD90), ventricular arrhythmias, indices of heart rate variability, left stellate ganglion nerve activity (LSGNA) and infarct sizes were measured and analyzed.
  
  
  RESULTS
  Ventricular ischemia resulted in an acute reduction of blood pressure, which was not significantly affected by LL-CBS. After 1 hour of LL-CBS, there was a progressive and significant increase in ERP, increase in APD90, and decrease in LSGNA vs the SHAM group (all P<0.05). LL-CBS apparently reduced premature ventricular contractions (PVC, 264±165 in the SHAM group vs 60±37 in the LL-CBS group; P<0.01) during LAD occlusion. Number of episodes of ventricular fibrillation (VF) was 8 in the Control group versus 3 in the LL-CBS group (80% versus 30%, P<0.05). LL-CBS obviously increased high frequency (HF) component (P<0.05) and decreased low frequency/high frequency ratio (P<0.05) compared with the SHAM group. Ischemic size was not affected by LL-CBS between the two groups.
  
  
  CONCLUSIONS
  LL-CBS reduced the occurrences of ventricular arrhythmias during acute ischemia without affecting blood pressure. The procedure was associated with changes of electrophysiological characteristics, nerve activity and heart rate variability. Therefore, LL-CBS may protect from ventricular arrhythmias during acute ischemic events by modulating ANS.
authors.affiliation: Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Liao
authors.affiliation: Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.
authors.forename: Lilei
authors.initials: L
authors.lastname: Yu
authors.affiliation: Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.
authors.forename: Kang
authors.initials: K
authors.lastname: Yang
authors.affiliation: Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.
authors.forename: Gaowa
authors.initials: G
authors.lastname: Saren
authors.affiliation: Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.
authors.forename: Songyun
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Huang
authors.affiliation: Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Jiang
mesh_terms: D000200:Action Potentials; D000208:Acute Disease; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000150:complications*; D002339:Carotid Arteries / Q000378:metabolism*; D054059:Coronary Occlusion / Q000150:complications; D004285:Dogs; D004558:Electric Stimulation; D005071:Evoked Potentials; D006352:Heart Ventricles / Q000503:physiopathology; D006439:Hemodynamics; D008297:Male; D017202:Myocardial Ischemia / Q000150:complications* / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D011311:Pressoreceptors / Q000378:metabolism*; D013233:Stellate Ganglion / Q000503:physiopathology