Document Detail

Is the QT interval an indicator of autonomic state?
MedLine Citation:
PMID:  11232988     Owner:  NLM     Status:  MEDLINE    
Prolonged QT interval is suggested to indicate an increased risk of sudden cardiac death in certain clinical conditions such as diabetes mellitus. We investigated whether the individual QT interval is an indicator of an autonomic state. An ambulatory 24-hour ECG was recorded in 53 subjects from different clinical backgrounds. Power spectral components of heart rate variability (HRV) and the QT interval were regressively obtained at a heart rate of 60, 70, 80, 90, or 100 beats per minutes (bpm). Log values of the high-frequency component of HRV (HF: 0.15-0.50 Hz, a scale of cardiac parasympathetic tone) failed to show a relationship with the QT interval. In contrast, the QT interval at a heart rate of 90 bpm and 100 bpm showed a significant correlation with the log values of the low-frequency component (LF: 0.04-0.15 Hz) and the log[LF/HF], i.e., a putative scale of sympathetic tone (100 bpm: QT vs logLF: r = 0.414, p < 0.005, QT vs log[LF/HF]: 0.416, p < 0.002). Also, attenuated rate-dependent QT shortening was associated with greater logLF and log[LF / HF] values at a heart rate of 80, 90, or 100 bpm. These results suggest that the QT interval at a moderate heart rate (approximately 90-100 / min) and the degree of rate-dependent QT shortening are related to individual sympathetic tone.
Y Murakawa; T Yamashita; K Ajiki; J Suzuki; N Hayami; E Fukui; Y Kasaoka; M Omata; R Nagai
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Japanese heart journal     Volume:  41     ISSN:  0021-4868     ISO Abbreviation:  Jpn Heart J     Publication Date:  2000 Nov 
Date Detail:
Created Date:  2001-03-05     Completed Date:  2001-03-08     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0401175     Medline TA:  Jpn Heart J     Country:  Japan    
Other Details:
Languages:  eng     Pagination:  713-21     Citation Subset:  IM    
Department of Cardiovascular Medicine, University of Tokyo, Japan.
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MeSH Terms
Autonomic Nervous System / physiopathology*
Coronary Disease / physiopathology
Diabetes Mellitus / physiopathology
Electrocardiography, Ambulatory*
Heart / innervation*
Heart Rate
Middle Aged
Parasympathetic Nervous System / physiopathology
Sympathetic Nervous System / physiopathology

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