Document Detail


Low doses of scopolamine increase cardiac vagal tone in the acute phase of myocardial infarction.
MedLine Citation:
PMID:  8339398     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Reduced cardiac vagal tone in patients with myocardial infarction (MI) is associated with a high risk of sudden death. Muscarinic blocking agents in small doses induce a paradoxical increase in cardiac vagal activity in normal subjects. We tested whether low doses of scopolamine delivered transdermally enhance tonic and reflex cardiac vagal activity in patients in the acute phase of MI. METHODS AND RESULTS: Patients were randomized to a scopolamine (n = 17) or a placebo patch (n = 19) in a double-blind fashion 4.20 +/- 0.18 days after acute MI. Cardiac vagal activity was assessed by testing the arterial baroreflex sensitivity (BRS) using the phenylephrine method and by power spectral analysis of the RR interval variability. Twenty-four hours after scopolamine, we found a significant increase in BRS (from 7.05 +/- 1.21 to 13.99 +/- 2.33 ms/mm Hg, P < .05) and in RR variability, expressed as the mean standard deviation of 512 normal consecutive RR intervals (from 18.09 +/- 2.64 to 31.16 +/- 4.16 milliseconds, P < .05). The amplitude of respiratory sinus arrhythmia, measured by the absolute power of the high-frequency spectral component, was also enhanced (from 62.55 +/- 21.49 to 305.33 +/- 95.68 milliseconds squared, P < .05), whereas the power in the low-frequency spectral component of the RR variability, which results from the interaction between cardiac sympathetic and vagal activity, did not change significantly (from 73.12 +/- 24.44 to 126.46 +/- 44.29 milliseconds squared, P = .93). CONCLUSIONS: In patients in the acute phase of MI, low doses of scopolamine cause a sustained increase in cardiac vagal tone and improve the autonomic indices associated with mortality.
Authors:
B Casadei; A Pipilis; F Sessa; J Conway; P Sleight
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Publication Detail:
Type:  Clinical Trial; Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Circulation     Volume:  88     ISSN:  0009-7322     ISO Abbreviation:  Circulation     Publication Date:  1993 Aug 
Date Detail:
Created Date:  1993-09-02     Completed Date:  1993-09-02     Revised Date:  2010-03-24    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  353-7     Citation Subset:  AIM; IM    
Affiliation:
Department of Cardiovascular Medicine, John Radcliffe Hospital, University of Oxford, England, UK.
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MeSH Terms
Descriptor/Qualifier:
Arteries / drug effects
Dose-Response Relationship, Drug
Double-Blind Method
Electrocardiography
Female
Heart Conduction System / drug effects*,  physiopathology
Humans
Male
Middle Aged
Myocardial Infarction / drug therapy*,  physiopathology*
Pressoreceptors / drug effects
Reflex / drug effects
Scopolamine / administration & dosage*,  therapeutic use
Vagus Nerve / drug effects*,  physiopathology
Chemical
Reg. No./Substance:
51-34-3/Scopolamine

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


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