Document Detail


Early morning reduction in ischemic threshold in patients with unstable angina and significant coronary disease.
MedLine Citation:
PMID:  7671355     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: The objective of this study was to investigate in patients with unstable angina and significant coronary stenosis (> 70%) whether or not the morning peak of myocardial ischemia is associated with a reduction in the ischemic threshold. The morning increased incidence of ischemic episodes in stable angina appears to be attributable to a coincidence of several factors. Patients with unstable angina who remain at bed rest, however, also present a similar morning increased incidence of ischemia, but its mechanisms are not completely understood. METHODS AND RESULTS: The ischemic threshold was assessed by atrial pacing at 7 to 8 AM and at 12 to 1 PM in 46 patients. In the 34 with a positive pacing response (ST segment shift > 1.0 mm), ischemic threshold was lower at 7 to 8 AM than at 12 to 1 PM (131 +/- 16 versus 139 +/- 15 beats per minute, P < .001), whereas in the remaining 12 patients, the pacing response was negative. Moreover, 4 patients presented ST segment elevation during pacing in the morning but only 1 at noon and at a higher threshold. Baseline heart rate and diastolic blood pressure were higher at noon than in the morning (81 +/- 16 versus 76 +/- 13 beats per minute, P < .01, and 87 +/- 11 versus 82 +/- 10 mm Hg, P < .05). CONCLUSIONS: The morning lowering of ischemic threshold in the absence of increases in baseline blood pressure or heart rate suggests that a reduced coronary vasodilator capacity or an increased coronary tone may favor the increased incidence of ischemic events during this interval.
Authors:
J Figueras; R M Lidón
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Circulation     Volume:  92     ISSN:  0009-7322     ISO Abbreviation:  Circulation     Publication Date:  1995 Oct 
Date Detail:
Created Date:  1995-10-19     Completed Date:  1995-10-19     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1737-42     Citation Subset:  AIM; IM    
Affiliation:
Unitat Coronària, Hospital General Vall d'Hebron, Barcelona, Spain.
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MeSH Terms
Descriptor/Qualifier:
Angina, Unstable / diagnosis,  physiopathology*
Bed Rest
Blood Pressure / physiology
Cardiac Pacing, Artificial
Circadian Rhythm / physiology*
Coronary Disease / diagnosis,  physiopathology*
Coronary Vessels / physiopathology*
Electrocardiography
Female
Heart Rate / physiology
Humans
Male
Middle Aged
Myocardial Ischemia / physiopathology*
Vascular Resistance / physiology
Vasodilation / physiology

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


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