Document Detail


Autonomic control of ventricular tachycardia: direct effects of beta-adrenergic blockade in 24 hour old canine myocardial infarction.
MedLine Citation:
PMID:  3805527     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The purpose of this study was to determine whether alpha- or beta-adrenergic influences directly modulate the rate of spontaneous ventricular tachycardia occurring 24 hours after left anterior descending coronary artery occlusion. Chloralose-anesthetized, open chest dogs (n = 41) with ventricular tachycardia were studied. The left anterior descending artery was cannulated distally. Neither intracoronary saline solution nor phenylephrine (0.3 to 12 micrograms) changed the rate of ventricular tachycardia; however, isoproterenol (0.01 to 10 micrograms) produced dose-dependent increases in the rate. In six dogs, metoprolol, 5 mg given intravenously, slowed ventricular tachycardia from 174 +/- 10 (mean +/- SE) to 140 +/- 17 beats/min (p less than 0.05). This was accompanied by decreases in mean arterial pressure from 106 +/- 7 to 95 +/- 8 mm Hg, cardiac output from 2.6 +/- 0.3 to 1.6 +/- 0.3 liters/min and prolongation of atrioventricular conduction from 134 +/- 10 to 189 +/- 29 ms (all p less than 0.05) during atrial pacing at a cycle length of 300 ms. In 10 dogs, metoprolol (0.5 mg) given intracoronary, a dose that shifted the isoproterenol dose-response curve to the right, slowed ventricular tachycardia from 174 +/- 7.2 to 140 +/- 9.7 beats/min (p less than 0.05) without hemodynamic changes. Additional metoprolol (4.5 mg) given intravenously produced hemodynamic alterations, but ventricular tachycardia did not slow further. Therefore, beta- but not alpha-adrenergic influences control the rate of ventricular tachycardia occurring 24 hours after left anterior descending coronary artery occlusion. Furthermore, beta-adrenergic blockade slows ventricular tachycardia solely by a direct electrophysiologic effect on the tachycardia foci and not indirectly as a result of hemodynamic effects.
Authors:
L Constantin; J B Martins
Related Documents :
3720767 - Ventricular late potentials and inducible ventricular tachyarrhythmias as a marker for ...
6630777 - Long-term follow-up of patients with recurrent unexplained syncope evaluated by electro...
657857 - Mechanical stimulation of the heart: its therapeutic value in tachyarrhythmias.
11232627 - Evidence of sinoatrial block as a curative mechanism in radiofrequency current ablation...
15145877 - A comparison of coronary artery stenting with angioplasty for isolated stenosis of the ...
10616877 - Fatty acid imaging with 123i-15-(p-iodophenyl)-9-r,s-methylpentadecanoic acid in acute ...
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of the American College of Cardiology     Volume:  9     ISSN:  0735-1097     ISO Abbreviation:  J. Am. Coll. Cardiol.     Publication Date:  1987 Feb 
Date Detail:
Created Date:  1987-03-06     Completed Date:  1987-03-06     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  8301365     Medline TA:  J Am Coll Cardiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  366-73     Citation Subset:  AIM; IM    
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:
Animals
Coronary Vessels
Dogs
Female
Heart Conduction System / drug effects
Hemodynamics / drug effects
Injections, Intra-Arterial
Isoproterenol / therapeutic use
Male
Metoprolol / administration & dosage,  pharmacology,  therapeutic use*
Myocardial Infarction / complications*
Phenylephrine / pharmacology*,  therapeutic use
Tachycardia / etiology,  prevention & control*
Grant Support
ID/Acronym/Agency:
HL 26567/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
37350-58-6/Metoprolol; 59-42-7/Phenylephrine; 7683-59-2/Isoproterenol

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


Previous Document:  Closed chest catheter desiccation of the atrioventricular junction using radiofrequency energy--a ne...
Next Document:  A nonflow basis for the vulnerability of the subendocardium.