Document Detail

Identifying coronary artery flow reduction and ischemia using quasistationary QT/RR-interval hysteresis measurements.
MedLine Citation:
PMID:  17993337     Owner:  NLM     Status:  MEDLINE    
Because myocardial ischemia induces QT/RR hysteresis, a correlation was hypothesized to exist between the extent of myocardial flow reduction and the magnitude of QT/RR hysteresis. Graded reductions in regional myocardial perfusion in the distribution of the left anterior descending coronary artery in open-chest pigs were used to model 1-vessel coronary artery disease. At each reduced level of left anterior descending coronary artery flow, the heart was electrically paced at progressively higher and lower rates between an initial control and maximum heart rate values. Digitized surface and intramyocardial electrograms and aortic pressure were used to measure QT/RR hysteresis, QT-interval adaptation, ST- and TQ-segment depression, and cardiac contractility. Intraexperimental blood samples were analyzed to assess inflammatory response (interleukin 6), oxidative stress (protein carbonyls), and myocyte injury (creatine kinase). Higher values of QT/RR hysteresis correlated with the severity of ischemia as assessed by TQ-segment depression in intramyocardial electrograms (P = .002). Lower flow rates were strongly associated with higher values of QT/RR hysteresis and slower QT-interval adaptation (P <or= .004), and were less correlated with the magnitude of ST- and TQ-segment depression (P >or= .02). Significant increases in systemic measures of inflammation, oxidative stress, and cardiac myocyte injury and major decrease in cardiac contractility preceded the most severe stages of flow reduction (30% and 20% of normal flow). We determined QT/RR hysteresis index thresholds corresponding to these mechanical and immunochemical responses. QT/RR hysteresis is a strong indicator of reduced myocardial perfusion and may provide information for noninvasive assessment of mechanical and immunochemical changes associated with early stages of coronary artery disease.
Joseph M Starobin; Wayne E Cascio; Allan H Goldfarb; Vivek Varadarajan; Andrei J Starobin; Christopher P Danford; Timothy A Johnson
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of electrocardiology     Volume:  40     ISSN:  1532-8430     ISO Abbreviation:  J Electrocardiol     Publication Date:    2007 Nov-Dec
Date Detail:
Created Date:  2007-11-12     Completed Date:  2008-01-07     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0153605     Medline TA:  J Electrocardiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  S91-6     Citation Subset:  IM    
Mediwave Star Technology, Inc, Greensboro, NC, USA.
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MeSH Terms
Blood Flow Velocity*
Coronary Circulation
Coronary Stenosis / diagnosis*,  physiopathology*
Diagnosis, Computer-Assisted / methods*
Electrocardiography / methods*
Heart Rate
Myocardial Ischemia / diagnosis*,  physiopathology*
Reproducibility of Results
Sensitivity and Specificity
Grant Support
R43 HL078027-01/HL/NHLBI NIH HHS

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

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