| Adrenergic effects on reentrant ventricular rhythms in subacute myocardial infarction. | |
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MedLine Citation:
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PMID: 1617776 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND: Reentry has been shown to be a mechanism of ventricular arrhythmias elicited by programmed premature stimulation in the subacute ischemic period of dogs subjected to myocardial infarction. The spatial distribution of refractoriness in these hearts has been shown to play an important part in the formation of functional arcs of conduction block during programmed ventricular stimulation. Because the adrenergic nervous system influences cardiac arrhythmias and myocardial infarction can directly affect sympathetic innervation in the heart, we investigated the role of the sympathetic nervous system on reentry in the canine heart 4 days after infarction. METHODS AND RESULTS: The influences of adrenergic stimuli on the initiation of reentrant ventricular excitation were studied using a 128-channel computerized recording system in the canine heart 4 days after ligation of the left anterior descending coronary artery. Bilateral stimulation of the ansae subclavia preferentially improved conduction of premature beats in the normal zones. This corresponded to an improvement in excitability, as measured by a decrease in stimulus strength at the same premature coupling interval as control. Consequently, the effective refractory period was preferentially shortened at normal sites but not at ischemic sites. Both of these changes contributed to a shift of the arc of functional conduction block toward more normal tissue. As a result, sites proximal to the arc of functional conduction block had more time to recover excitability and thereby were available to be reexcited by the distal activation wave front. Conversely, intravenous infusion of norepinephrine preferentially shortened the effective refractory period of sites in the ischemic zone, thereby indicating that denervation hypersensitivity had occurred at these sites. The spatial dispersion of refractoriness and the arc of functional conduction block were significantly reduced in size. As a consequence, previously inducible reentrant rhythms were no longer inducible. CONCLUSIONS: Sympathetic stimulation can be considered an arrhythmogenic intervention, whereas norepinephrine infusion may be considered antiarrhythmic in this experimental model. |
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Authors:
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G S Butrous; W B Gough; M Restivo; H Yang; N el-Sherif |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Circulation Volume: 86 ISSN: 0009-7322 ISO Abbreviation: Circulation Publication Date: 1992 Jul |
Date Detail:
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Created Date: 1992-08-06 Completed Date: 1992-08-06 Revised Date: 2010-03-24 |
Medline Journal Info:
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Nlm Unique ID: 0147763 Medline TA: Circulation Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 247-54 Citation Subset: AIM; IM |
Affiliation:
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Department of Medicine, State University of New York Health Science Center, Brooklyn. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Arrhythmias, Cardiac / etiology, physiopathology* Cardiac Pacing, Artificial Dogs Electric Stimulation Heart Ventricles Myocardial Infarction / complications* Norepinephrine / pharmacology Pericardium / drug effects, physiopathology Refractory Period, Electrophysiological Sympathetic Nervous System / physiopathology Sympathomimetics / pharmacology* |
| Grant Support | |
ID/Acronym/Agency:
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HL-36680/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Sympathomimetics; 51-41-2/Norepinephrine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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