Abstract
Background: Low-frequency (LF) and high-frequency (HF) components of RR interval (RR) variability are widely used as indirect markers of cardiac autonomic control but their reproducibility is unknown. We determined the intra-class correlation coefficients (ICC) of repeated measures of the mean levels and variability of RR and muscle sympathetic nerve activity (MSNA) in 7 normal subjects. We also determined whether spontaneous fluctuations in RR and MSNA over repeated measurements were mirrored by fluctuations in spectral components of these variables. Methods: Twenty minute recordings of respiration, RR, blood pressure (BP) and MSNA were performed at day 1, 1 week, 1 month and 3 months. Comparison between these recordings determined the long-term reliability. Results: The long-term reliability of the variability of RR was comparable to the variability of MSNA (range of ICC: .34 - .52). Spontaneous decreases in RR during the repeated recordings were paralleled by increases in the ratio of low-frequency to high-frequency variability (LF:HF ratio) of RR interval (r=-.43, p
| Original language | English |
|---|---|
| Journal | FASEB Journal |
| Volume | 11 |
| Issue number | 3 |
| Publication status | Published - 1997 |
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)
- Biochemistry, Genetics and Molecular Biology(all)
- Biochemistry
- Cell Biology