Document Detail

Urban ectopy in the mountains: carbon monoxide exposure at high altitude.
MedLine Citation:
PMID:  8757408     Owner:  NLM     Status:  MEDLINE    
Environmental exposure to inhaled carbon monoxide (CO) increases coronary artery disease risk. Sudden cardiac death, a frequent manifestation of coronary artery disease, is usually a result of ventricular dysrhythmia. The effect of exposure to CO at sea level (CO/SL) and simulated high (2.1 km) altitudes (CO/HA) on the incidence of cardiac ectopy in subjects with coronary artery disease was investigated. A double-blind crossover study was conducted, with random-order assignment, and each subject served as his own control. Seventeen men with documented coronary artery disease and stable angina pectoris performed cardiopulmonary exercise stress tests after random exposure to either CO or clean air (CA) at sea level (CA/SL) or at a simulated 2.1-km high altitude (CA/HA). The individual CO and HA exposure conditions were each selected to reduce the percentage of oxygen saturation of the subjects' arterial blood by 4%. Subjects' blood carboxyhemoglobin levels were increased from an average of 0.62% after clean-air exposure to 3.91% of saturation after CO exposure. The percentage of oxygen saturation in arterial blood was reduced from a baseline level of 98% to approximately 94% after CO/SL or CA/HA and to approximately 90% after CO/HA. Compared with the CA/SL (i.e., 10 premature ventricular contractions [PVCs]), the average incidence of exercise-induced ventricular ectopy was approximately doubled after all exposures (CO/SL = 18 PVCs, CA/HA = 16 PVCs, and CO/HA = 19 PVCs), and a significant trend (p < .05) of increased ectopy with decreased oxygen saturation in arterial blood was observed. Yet, among subjects who were free from ectopy (n = 11) on CA/SL, only 2 subjects developed ectopy after CO/HA. No episodes of ventricular tachycardia or fibrillation occurred. The findings indicated that exposure to increased levels of hypoxemia, resulting from hypoxic and/or CO exposures, increased the susceptibility to ventricular ectopy during exercise in individuals with stable angina pectoris; however, this risk was nominal for those without ectopy.
D A Leaf; M T Kleinman
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Archives of environmental health     Volume:  51     ISSN:  0003-9896     ISO Abbreviation:  Arch. Environ. Health     Publication Date:    1996 Jul-Aug
Date Detail:
Created Date:  1996-09-17     Completed Date:  1996-09-17     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0212627     Medline TA:  Arch Environ Health     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  283-90     Citation Subset:  AIM; IM    
Department of Medicine, West Los Angeles V.A. Medical Center, California 90073, USA.
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MeSH Terms
Aged, 80 and over
Air Pollutants / adverse effects*
Angina Pectoris / blood,  complications,  diagnosis
Arrhythmias, Cardiac / blood,  chemically induced*,  diagnosis,  epidemiology
Carbon Monoxide / adverse effects*
Coronary Disease / blood,  complications,  diagnosis
Cross-Over Studies
Double-Blind Method
Exercise Test
Middle Aged
Urban Population*
Reg. No./Substance:
0/Air Pollutants; 630-08-0/Carbon Monoxide

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

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