Document Detail

Evidence for a link between mechanical and electrical alternans in acutely ischaemic myocardium of anaesthetized dogs.
MedLine Citation:
PMID:  1711268     Owner:  NLM     Status:  MEDLINE    
In order to examine the relation between mechanical alternans and associated electrical alternans during acute myocardial ischaemia, we determined the effect of a ventricular premature beat and calcium antagonists on mechanical and electrical alternans during acute coronary occlusion in anaesthetized dogs. Isometric contractions and unipolar electrocardiograms were recorded from ischaemic myocardium. During coronary occlusion, mechanical alternans was accompanied by electrical alternans, which was an alternate change in the ST segment elevation, i.e. the higher ST and the lower ST. Electrical alternans was frequently discordant and in some cases accompanied by discordant mechanical alternans. Both discordant electrical and mechanical alternans became concordant and were potentiated after the ventricular premature beat. In all cases, concordant mechanical alternans was accompanied by concordant electrical alternans and vice versa. In this situation, the higher and the lower ST corresponded to the larger and the smaller contractions respectively. Thus, a fixed correspondence was observed between mechanical and electrical alternans. A fixed correspondence was also observed between mechanical alternans and the variation in the time taken for repolarization of the monophasic action potential. Verapamil and diltiazem inhibited both electrical and mechanical alternans. The present results support the idea that a common mechanism, such as a beat-to-beat cycle of the transmembrane and intracellular movement of calcium ions, may play a role in the mechanisms of electrical and mechanical alternans.
H Hashimoto; M Nakashima
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Acta physiologica Scandinavica     Volume:  141     ISSN:  0001-6772     ISO Abbreviation:  Acta Physiol. Scand.     Publication Date:  1991 Jan 
Date Detail:
Created Date:  1991-07-19     Completed Date:  1991-07-19     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370362     Medline TA:  Acta Physiol Scand     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  63-70     Citation Subset:  IM    
Department of Pharmacology, Hamamatsu University School of Medicine, Japan.
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MeSH Terms
Calcium Channel Blockers / pharmacology
Cardiac Complexes, Premature / pathology,  physiopathology
Coronary Disease / pathology,  physiopathology*
Diltiazem / pharmacology
Electric Stimulation
Myocardial Contraction* / drug effects
Physical Stimulation
Pulse / drug effects
Verapamil / pharmacology
Reg. No./Substance:
0/Calcium Channel Blockers; 42399-41-7/Diltiazem; 52-53-9/Verapamil

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

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