Document Detail


Experimental study of the effect of the vagus nerve on atrial electrical remodeling.
MedLine Citation:
PMID:  14661165     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Recent studies have shown that rapid atrial activation causes atrial electrical remodeling (AER), which recovers quickly following withdrawal of stimulation. The underlying mechanisms, however, are incompletely understood. The purpose of the present study, therefore, was to characterize the effect of the vagus on AER as well as define possible mechanisms of the phenomenon. Eight dogs were used in the study for 3 consecutive protocols. In the first, the dogs were subjected to atrial pacing at 800 ppm for 7 hours. Every hour, pacing was interrupted for a short time and atrial effective refractory period (AERP) was measured at 6 sites. The rapid atrial pacing was then discontinued and the electrophysiological study was repeated every hour for another 7 hours. Time-domain parameters of heart rate variability (HRV) were also computed 1 hour before pacing as well as each of 7 hours after the rapid atrial pacing protocol. The second program was performed two weeks after the first; 0.04 mg/kg of atropine was administered intravenously 30 min before pacing, and then 0.007 mg/kg was added at each hour. Parameters of HRV were not evaluated. Finally, the 8 dogs were subjected to the third protocol 2 weeks after completion of the second; 0.2 mg/kg of propranolol was given intravenously 30 min before pacing, and 0.04 mg/kg was added at each hour. The dispersion of AERP (dAERP) was calculated as, maximum AERP minus minimum AERP. There was a prompt decrease in AERP as the result of pacing (P<.05), but dAERP did not change significantly. The AERP recovered quickly, and dAERP increased from 21 +/-5.3 ms to 40 +/- 7.4 ms (P<.05) after cessation of pacing. At the same time, the parameters of HRV increased (P<.05) after cessation of pacing. The AERP increased from 128 +/- 12 ms to 135 +/- 12 ms and from 127 +/- 12 ms to 142 +/- 14 ms (P<.05) after vagal and autonomic blockade. However, AERP decreased during pacing (P<.05) with vagal or autonomic blockade, but dAERP did not change significantly during or after pacing. These results suggest that vagal and autonomic blockade can not prevent AER, but a high vagal tone is associated with a high dAERP during recovery from AER, indicating that the vagus and sympathetic have a synergistic effect on the refractory period.
Authors:
Cong-Xin Huang; Qing-Yan Zhao; Hong Jiang; Jian-Jun Li; Bo Yang
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Journal of electrocardiology     Volume:  36     ISSN:  0022-0736     ISO Abbreviation:  J Electrocardiol     Publication Date:  2003 Oct 
Date Detail:
Created Date:  2003-12-08     Completed Date:  2005-06-28     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0153605     Medline TA:  J Electrocardiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  295-300     Citation Subset:  IM    
Affiliation:
Department of Cardiology, Renmin Hospital, Wuhan University School of Medicine, People's Republic of China. Hunagcongxin@yahoo.com
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MeSH Terms
Descriptor/Qualifier:
Animals
Anti-Arrhythmia Agents / administration & dosage
Atrial Function / drug effects,  physiology*
Atropine / administration & dosage
Cardiac Pacing, Artificial
Dogs
Electric Stimulation
Electrophysiologic Techniques, Cardiac
Heart Atria / chemistry,  drug effects
Heart Rate / drug effects,  physiology
Infusions, Intravenous
Models, Animal
Models, Cardiovascular
Propranolol / administration & dosage
Refractory Period, Electrophysiological / drug effects
Vagus Nerve / drug effects,  physiology*
Chemical
Reg. No./Substance:
0/Anti-Arrhythmia Agents; 51-55-8/Atropine; 525-66-6/Propranolol

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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