| Fractal component of variability of heart rate and systolic blood pressure in congestive heart failure. | |
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MedLine Citation:
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PMID: 9205413 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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1. There is a substantial non-harmonic or fractal component to the variability of both heart rate and blood pressure in normal subjects. Heart rate is the more complex of these two signals, with respect to the slope, beta, of the 1/f beta relationship. In congestive heart failure, heart rate spectral power is attenuated, but the fractal and harmonic components of heart rate and systolic blood pressure variability have not been characterized. 2. Two groups, each comprising 20 men, were studied during 15 min of supine rest and spontaneous respiration: one with functional class II-IV heart failure (age 52 +/- 2 years; mean +/- SEM) and a second group of healthy men (age 46 +/- 2 years). 3. Total spectral power for heart rate was significantly reduced in heart failure (P < 0.02), whereas total spectral power for systolic blood pressure was similar in the two groups. In both heart failure and normal subjects, 65-80% of total spectral power in these two signals displayed fractal characteristics. 4. In heart failure, the slope of the 1/f beta relationship for heart rate was significantly steeper than in normal subjects (1.40 +/- 0.08 compared with 1.14 +/- 0.05; P < 0.05), indicating reduced complexity of the fractal component of heart rate variability. There was no significant difference in the 1/f beta slope for systolic blood pressure variability between these two groups, but the blood pressure signals were less complex than heart rate variations in both heart failure (2.31 +/- 0.15; P < 0.006) and normal subjects (2.47 +/- 0.15; P < 0.0001). 5. Parasympathetic nervous system activity, as estimated from heart rate variability was reduced (P < 0.01) in patients with heart failure, whereas trends towards increased sympathetic nervous system activity and decreased non-harmonic power were not significant. 6. The non-harmonic components of cardiac frequency are reduced in heart failure. Non-harmonic power is not attenuated, but the complexity of the heart rate signal is less than in subjects with normal ventricular function. A reduction in parasympathetic modulation appears to contribute to this loss of complexity of heart rate. Consequently, the heart rate signal comes to resemble that of blood pressure. In contrast, the variability and complexity of the systolic blood pressure signal is similar in heart failure and normal subjects. This reduced complexity of heart rate variability may have adverse implications for patients with heart failure. |
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Authors:
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G C Butler; S Ando; J S Floras |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Clinical science (London, England : 1979) Volume: 92 ISSN: 0143-5221 ISO Abbreviation: Clin. Sci. Publication Date: 1997 Jun |
Date Detail:
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Created Date: 1997-07-11 Completed Date: 1997-07-11 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 7905731 Medline TA: Clin Sci (Lond) Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 543-50 Citation Subset: IM |
Affiliation:
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Division of Cardiology, Mount Sinai Hospital, Toronto, Ontario, Canada. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Blood Pressure* Electrocardiography Fractals* Heart Failure / physiopathology* Heart Rate* Humans Male Middle Aged Parasympathetic Nervous System / physiopathology Signal Processing, Computer-Assisted Systole |
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