Document Detail

Continuous assessment of hemodynamic control by complex demodulation of cardiovascular variability.
MedLine Citation:
PMID:  8476100     Owner:  NLM     Status:  MEDLINE    
Usefulness of complex demodulation (CDM) in assessing the frequency components of cardiovascular variability was assessed and, subsequently, this technique was utilized to determine the time-dependent responses of the low-frequency (LF) and high-frequency (HF) amplitudes of heart rate and blood pressure variabilities during postural tilt. CDM provides the time-dependent changes in amplitude of a particular frequency component on a continuous basis. Analysis of simulated data showed that CDM has sufficient frequency resolution to separately measure LF and HF amplitudes with a time resolution < 15 s and that CDM is robust to alterations in the frequency of the components. Analysis of actual data during postural tilt test in 23 young healthy subjects demonstrated that the HF amplitude of heart rate, an index of cardiac parasympathetic tone, rapidly decayed with head-up tilt (P < 0.01) and increased quickly showing an overshoot with tilt back to the supine position (P < 0.01). The LF amplitude of blood pressure, an index of vasomotor sympathetic activity, showed marked rhythmic fluctuation at an interval of 48-100 s during head-up tilt (P < 0.01), synchronizing with similar fluctuation in the LF amplitude of heart rate (P < 0.01). These results suggest that CDM can be used to provide a continuous assessment of cardiovascular variability components and that the dynamic responses of autonomic circulatory control to upright posture result in a phasic modulation of LF amplitude.
J Hayano; J A Taylor; A Yamada; S Mukai; R Hori; T Asakawa; K Yokoyama; Y Watanabe; K Takata; T Fujinami
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of physiology     Volume:  264     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1993 Apr 
Date Detail:
Created Date:  1993-05-17     Completed Date:  1993-05-17     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H1229-38     Citation Subset:  IM; S    
Third Department of Internal Medicine, Nagoya City University Medical School, Japan.
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MeSH Terms
Autonomic Nervous System / physiology
Blood Pressure / physiology
Cardiovascular Physiological Phenomena*
Cardiovascular System / innervation
Electric Stimulation
Heart Rate / physiology
Hemodynamics / physiology
Posture / physiology
Time Factors

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