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Analysis of changes in cardiac circadian rhythms of RR and QT induced by a 60-day head-down bed rest with and without nutritional countermeasure

Solbiati, S. ; Landreani, F. ; Turcato, M. ; Martin-Yebra, A. LU ; Costantini, L. ; Vaida, P. and Caiani, Enrico G. (2020) In European Journal of Applied Physiology 120(7). p.1699-1710
Abstract

Purpose: Prolonged weightlessness exposure generates cardiovascular deconditioning, with potential implications on ECG circadian rhythms. Head-down (− 6°) tilt (HDT) bed rest is a ground-based analogue model for simulating the effects of reduced motor activity and fluids redistribution occurring during spaceflight. Our aim was to evaluate the impact of 60-day HDT on the circadianity of RR and ventricular repolarization (QTend) intervals extracted from 24-h Holter ECG recordings, scheduled 9 days before HDT (BDC-9), the 5th (HDT5), 21st (HDT21) and 58th (HDT58) day of HDT, the 1st (R + 0) and 8th (R + 7) day after HDT. Also, the effectiveness of a nutritional countermeasure (CM) in mitigating the HDT-related changes was tested. Methods:... (More)

Purpose: Prolonged weightlessness exposure generates cardiovascular deconditioning, with potential implications on ECG circadian rhythms. Head-down (− 6°) tilt (HDT) bed rest is a ground-based analogue model for simulating the effects of reduced motor activity and fluids redistribution occurring during spaceflight. Our aim was to evaluate the impact of 60-day HDT on the circadianity of RR and ventricular repolarization (QTend) intervals extracted from 24-h Holter ECG recordings, scheduled 9 days before HDT (BDC-9), the 5th (HDT5), 21st (HDT21) and 58th (HDT58) day of HDT, the 1st (R + 0) and 8th (R + 7) day after HDT. Also, the effectiveness of a nutritional countermeasure (CM) in mitigating the HDT-related changes was tested. Methods: RR and QTend circadian rhythms were evaluated by Cosinor analysis, resulting in maximum and minimum values, MESOR (a rhythm-adjusted mean), oscillation amplitude (OA, half variation within a night–day cycle), and acrophase (φ, the time at which the fitting sinusoid’s amplitude is maximal) values. Results: RR and QTend MESOR increased at HDT5, and the OA was reduced along the HDT period, mainly due to the increase of the minima. At R + 0, QTend OA increased, particularly in the control group. The φ slightly anticipated during HDT and was delayed at R + 0. Conclusion: 60-Day HDT affects the characteristics of cardiac circadian rhythm by altering the physiological daily cycle of RR and QTend intervals. Scheduled day–night cycle and feeding time were maintained during the experiment, thus inferring the role of changes in the gravitational stimulus to determine these variations. The applied nutritional countermeasure did not show effectiveness in preventing such changes.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Cardiac deconditioning, Circadian rhythm, Head-down bed rest, Heart rate, Nutrition, Ventricular repolarization
in
European Journal of Applied Physiology
volume
120
issue
7
pages
12 pages
publisher
Springer
external identifiers
  • pmid:32494859
  • scopus:85085883357
ISSN
1439-6319
DOI
10.1007/s00421-020-04404-7
language
English
LU publication?
yes
id
2375307e-f581-4bfd-8dcd-d17801e845af
date added to LUP
2020-07-02 11:54:50
date last changed
2020-07-03 01:58:44
@article{2375307e-f581-4bfd-8dcd-d17801e845af,
  abstract     = {<p>Purpose: Prolonged weightlessness exposure generates cardiovascular deconditioning, with potential implications on ECG circadian rhythms. Head-down (− 6°) tilt (HDT) bed rest is a ground-based analogue model for simulating the effects of reduced motor activity and fluids redistribution occurring during spaceflight. Our aim was to evaluate the impact of 60-day HDT on the circadianity of RR and ventricular repolarization (QTend) intervals extracted from 24-h Holter ECG recordings, scheduled 9 days before HDT (BDC-9), the 5th (HDT5), 21st (HDT21) and 58th (HDT58) day of HDT, the 1st (R + 0) and 8th (R + 7) day after HDT. Also, the effectiveness of a nutritional countermeasure (CM) in mitigating the HDT-related changes was tested. Methods: RR and QTend circadian rhythms were evaluated by Cosinor analysis, resulting in maximum and minimum values, MESOR (a rhythm-adjusted mean), oscillation amplitude (OA, half variation within a night–day cycle), and acrophase (φ, the time at which the fitting sinusoid’s amplitude is maximal) values. Results: RR and QTend MESOR increased at HDT5, and the OA was reduced along the HDT period, mainly due to the increase of the minima. At R + 0, QTend OA increased, particularly in the control group. The φ slightly anticipated during HDT and was delayed at R + 0. Conclusion: 60-Day HDT affects the characteristics of cardiac circadian rhythm by altering the physiological daily cycle of RR and QTend intervals. Scheduled day–night cycle and feeding time were maintained during the experiment, thus inferring the role of changes in the gravitational stimulus to determine these variations. The applied nutritional countermeasure did not show effectiveness in preventing such changes.</p>},
  author       = {Solbiati, S. and Landreani, F. and Turcato, M. and Martin-Yebra, A. and Costantini, L. and Vaida, P. and Caiani, Enrico G.},
  issn         = {1439-6319},
  language     = {eng},
  number       = {7},
  pages        = {1699--1710},
  publisher    = {Springer},
  series       = {European Journal of Applied Physiology},
  title        = {Analysis of changes in cardiac circadian rhythms of RR and QT induced by a 60-day head-down bed rest with and without nutritional countermeasure},
  url          = {http://dx.doi.org/10.1007/s00421-020-04404-7},
  doi          = {10.1007/s00421-020-04404-7},
  volume       = {120},
  year         = {2020},
}