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Titolo:
Effect of posture and isoproterenol on beat-to-beat heart rate and QT variability
Autore:
Yeragani, VK; Pohl, R; Jampala, VC; Balon, R; Kay, J; Igel, G;
Indirizzi:
Wayne State Univ, Sch Med, Dept Psychiat, Detroit, MI 48202 USA Wayne State Univ Detroit MI USA 48202 ept Psychiat, Detroit, MI 48202 USA Wright State Univ, Sch Med, Dayton, OH 45435 USA Wright State Univ DaytonOH USA 45435 Univ, Sch Med, Dayton, OH 45435 USA Vet Affairs Med Ctr, Dayton, OH USA Vet Affairs Med Ctr Dayton OH USAVet Affairs Med Ctr, Dayton, OH USA
Titolo Testata:
NEUROPSYCHOBIOLOGY
fascicolo: 3, volume: 41, anno: 2000,
pagine: 113 - 123
SICI:
0302-282X(2000)41:3<113:EOPAIO>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
VENTRICULAR REPOLARIZATION DURATION; 24-HOUR HOLTER RECORDINGS; MYOCARDIAL-INFARCTION; INTERVAL VARIABILITY; FRACTAL DIMENSION; SPECTRAL-ANALYSIS; DIURNAL-VARIATION; FREQUENCY-DOMAIN; RR; PERIOD;
Keywords:
QT variability; sympathetic activity; posture; isoproterenol; fractal dimension;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
32
Recensione:
Indirizzi per estratti:
Indirizzo: Yeragani, VK Flat 16,KCN Mans,Madhav Nagar, Bangalore 560001, Karnataka, India Flat 16,KCN Mans,Madhav Nagar Bangalore Karnataka India 560001
Citazione:
V.K. Yeragani et al., "Effect of posture and isoproterenol on beat-to-beat heart rate and QT variability", NEUROPSYCHB, 41(3), 2000, pp. 113-123

Abstract

Rationale: Recent literature emphasizes the utility of QT variability to study ventricular electrophysiologic function, in this investigation, we sought to test the hypothesis that beat-to-beat fluctuations in QT intervals are mediated by sympathetic activity in normal subjects using postural challenge and isoproterenol infusions. Subjects and Methods: We obtained ECG in the supine and standing postures during spontaneous breathing, at 12, 15 and 20 per minute controlled breathing (n = 19), and before and after infusions of isoproterenol, a beta-adrenergic agent, in the supine posture during spontaneous breathing (n = 11) using lead II configuration in healthy humanadult subjects. Heart rate (HR) and QT time series data were analyzed by spectral analysis of 256 s of real-time data. Beat-to-beat QT intervals weremeasured by automated analysis of ECG. A QT variability index (QT(vi)) wascalculated for each subject as the logarithm of the ratio of normalized QTvariance to normalized HR variance. We also calculated fractal dimensions of QT time series during spontaneous breathing. Results: QT(vi) was significantly higher in the standing than in the supine posture (-1.93 +/- 0.27 vs. -1.47 +/- 0.41; p = 0.0001), and also during isoproterenol infusions in the supine posture (-1.83 +/- 0.39 vs. -1.27 +/- 0.43; p = 0.0001). Fractal dimensions of QT time series were also significantly higher during standing(p = 0.00001) and isoproterenol infusions (p = 0.0002). Respiratory rate or tidal volume did not account for the increased QT variability seen in thestanding posture. Conclusions: A change from the supine to the standing posture as well as infusion of isoproterenol significantly increased the absolute as well as normalized QT variability, which appears to be due to an increase in sympathetic activity associated with these conditions. Copyright (C) 2000 S. Karger AG, Basel.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/09/20 alle ore 23:32:05