Document Detail

Ability of short-time Fourier transform method to detect transient changes in vagal effects on hearts: a pharmacological blocking study.
MedLine Citation:
PMID:  16361363     Owner:  NLM     Status:  MEDLINE    
Conventional spectral analyses of heart rate variability (HRV) have been limited to stationary signals and have not allowed the obtainment of information during transient autonomic cardiac responses. In the present study, we evaluated the ability of the short-time Fourier transform (STFT) method to detect transient changes in vagal effects on the heart. We derived high-frequency power (HFP, 0.20-0.40 Hz) as a function of time during active orthostatic task (AOT) from the sitting to standing posture before and after selective vagal (atropine sulfate 0.04 mg/kg) and sympathetic (metoprolol 0.20 mg/kg) blockades. The HFP minimum point during the first 30 s after standing up was calculated and compared with sitting and standing values. Reactivity scores describing the fast and slow HFP responses to AOT were calculated by subtracting the minimum and standing values from the sitting value, respectively. The present results, obtained without controlled respiration, showed that in the drug-free condition, HFP decreased immediately after standing up (P < 0.001) and then gradually increased toward the level characteristic for the standing posture (P < 0.001), remaining lower than in the sitting baseline posture (P < 0.001). The magnitudes of the fast and slow HFP responses to AOT were abolished by the vagal blockade (P < 0.001) and unaffected by the sympathetic blockade. These findings indicate that HFP derived by the STFT method provided a tool for monitoring the magnitude and time course of transient changes in vagal effects on the heart without the need to interfere with normal control by using blocking drugs.
Kaisu Martinmäki; Heikki Rusko; Sami Saalasti; Joni Kettunen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-12-16
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  290     ISSN:  0363-6135     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2006 Jun 
Date Detail:
Created Date:  2006-05-11     Completed Date:  2006-06-22     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  H2582-9     Citation Subset:  IM    
KIHU-Research Institute for Olympic Sports, and Department of Biology of Physical Activity, University of Jyväskylä, FI-40014 Jyväskylä, Finland.
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MeSH Terms
Adrenergic beta-Antagonists / pharmacology
Atropine / pharmacology
Autonomic Agents / pharmacology
Blood Pressure / drug effects,  physiology
Dizziness / physiopathology
Fourier Analysis*
Heart / drug effects*,  innervation*
Metoprolol / pharmacology
Muscarinic Antagonists / pharmacology
Posture / physiology
Sympathetic Nervous System / drug effects
Vagus Nerve / drug effects*,  physiology*
Reg. No./Substance:
0/Adrenergic beta-Antagonists; 0/Autonomic Agents; 0/Muscarinic Antagonists; 37350-58-6/Metoprolol; 51-55-8/Atropine

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

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