Document Detail

Subendocardial ischemia provoked by tachycardia in conscious dogs with coronary stenosis.
MedLine Citation:
PMID:  1109244     Owner:  NLM     Status:  MEDLINE    
We investigated the effect that mild coronary stenosis exerts on the ability of the coronary circulation to compensate for the increased extravascular compression that occurs in the subendocardium during tachycardia. An electromagnetic flowmeter transducer and balloon cuff occluder were implanted on the left circumflex coronary artery in seven dogs, and experiments were performed 1 week later with the dogs under sedation but conscious. Stenosis of the left circumflex artery was produced by partial inflation of the cuff occluder. We determined coronary blood flow distribution by the radioactive microsphere technique, injection 200,000 15mu spheres into the left ventricular cavity during (1) a control period, (2) stenosis of the left circumflex artery and a normal heart rate, and (3) stenosis of the left circumflex artery and tachycardia. When the heart rate was normal, the degree of stenosis used caused no change in myocardial microsphere distribution but eliminated postocclusion reactive hyperemia. Thus, reserve coronary vasodilation compensated for the stenosis. With the degree of stenosis kept constant, an increase in heart rate to 196 beats/min caused a marked transmural shift in distribution of microspheres from subendocardium into subepicardium within the region of the left ventricle supplied by the left circumflex artery. There was no significant transmural shift in the region supplied by the uninvolved left anterior descending coronary artery. Myocardial lactate extraction decreased. These results suggest that when reserve coronary vasodilation has already been utilized to compensate for coronary stenosis, the increased extravascular coronary compression from tachycardia causes subendocardial ischemia and hypoxia.
W A Neill; J Oxendine; N Phelps; R P Anderson
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The American journal of cardiology     Volume:  35     ISSN:  0002-9149     ISO Abbreviation:  Am. J. Cardiol.     Publication Date:  1975 Jan 
Date Detail:
Created Date:  1975-02-18     Completed Date:  1975-02-18     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0207277     Medline TA:  Am J Cardiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  30-6     Citation Subset:  AIM; IM    
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MeSH Terms
Blood Flow Velocity
Coronary Circulation*
Coronary Disease / physiopathology*
Heart Ventricles / metabolism
Lactates / metabolism
Myocardium / metabolism
Statistics as Topic
Strontium Radioisotopes
Tachycardia / chemically induced,  complications*,  physiopathology
Reg. No./Substance:
0/Lactates; 0/Radioisotopes; 0/Strontium Radioisotopes; 51-55-8/Atropine; 7440-03-1/Niobium; 7440-46-2/Cesium

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

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