TITLE

Effects of nicardipine and diltiazem on fractal features of short-term heart rate variability—application of coarse graining spectral analysis

AUTHOR(S)
Koh, Junken; Hidaka, Ichiro; Miyata, Masahiko
PUB. DATE
May 2002
SOURCE
Journal of Anesthesia;2002, Vol. 16 Issue 2, p108
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
.Purpose. This study was designed to investigate the effects of nicardipine and diltiazem on the fractal features of short-term heart rate variability (HRV), using coarse graining spectral analysis (CGSA).Methods. Eighteen healthy volunteers participated in this study; they were divided into two groups according to the drug administered. Five-minute electrocardiogram and arterial pressure recordings were made during stepwise infusions of either nicardipine (0.4, 0.8, 1.6, and 3.2 μg·kg[sup -1] ·min[sup -1] ) or diltiazem (2, 4, 8, and 16 μg·kg[sup -1] ·min[sup -1] ) under rate-controlled breathing at 0.25 Hz. CGSA broke down the total power of the time series into harmonic (low frequency [0.0–0.15 Hz; LF] and high frequency [0.15–0.5 Hz; HF]) and nonharmonic (fractal) components. Cardiac sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) activity indicators were evaluated as the ratios LF/HF and HF/TP (total spectral power), respectively. Fractal components were evaluated as %fractal and the spectral exponent β of 1/f[sup β] .Results. Compared with control measurements, the maximum dose of nicardipine infusion caused a significant decrease in systolic arterial pressure, a significant increase in the mean heart rate, and a significant increase in plasma norepinephrine level, findings that were associated with significant increases in %fractal and β values (54.2 ± 13.3 vs 75.6 ± 9.8, and 0.86 ± 0.22 vs 1.32 ± 0.46, respectively; P < 0.05). PNS and SNS indicators showed decreased and increased values, respectively. Diltiazem caused a reduction in arterial pressure; however, no other parameters, including the nonharmonic components of HRV, were affected by this drug.Conclusions. These findings strongly suggest that nicardipine suppresses vagal cardiac neural outflow and activate the SNS, an action which, subsequently, causes changes in the fractal features of HRV....
ACCESSION #
6688442

 

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