Miocardium bioelectrical characteristics, autonomic regulation and circadian rhythms in space
- Paper number
IAC-18,A1,2,3,x46395
- Author
Dr. Vasily Rusanov, Russian Federation, Institute for Bio-Medical Problems of RAS
- Coauthor
Prof. Roman Baevsky, Russian Federation, SSC RF Institute of bio-medical problems RAS
- Coauthor
Ms. Olga Isaeva, Russian Federation, SSC RF-Institute of Biomedical Problems RAS
- Coauthor
Dr. Anna Chernikova, Russian Federation, SSC RF Institute of Biomedical problems of RAS
- Year
2018
- Abstract
Background. Assessment and prediction of possible health risks is one of the main objectives for medical control system in future interplanetary space flights. Not only environmental stressors (microgravity, radiation, confined living place, workloads) but low functionality of different body systems in space may become one of the limiting factors for medical care. So, we must be focused on use of instruments for early detection of health disorders. Materials and methods. “Cosmocard” experiment involves Russian ISS crew-members and consists of 24-hours ECG monitoring with further analysis of ECG-signal electrical microalternations in 30-sec ECG samples (ECG dispersion mapping) and of autonomic regulation (heart rate variability analysis) in 5-min ECG samples. We also study the circadian rhythms of these processes. Data analysis provides the calculation of averaged hour-to-hour, daily, day and night values of all parameters. Investigations are conducted twice before flight, every month in-flight and +1, +7 days after landing. The results for 12 cosmonauts in 6-months missions are presented. Results. By the results of 24-hours ECG monitoring we observe the shift of autonomic balance towards reduced parasympathetic activity under long action of microgravity. This is especially evident in the decreased daily mean values of HRV parameter pNN50 during space flight (5,29 ±0,15 % vs 9,04± 0,7% before flight). Daily heart rate (HR) values during flight are slightly lower than preflight values (66.87 ± 0.26 bpm vs 68.56 ± 0.83 bpm). According to the results of ECG dispersion mapping the greatest changes during space flight have been identified in "electrical instability index", which is decreased during the flight (1,08 ± 0,003 vs 1,13 ± 0,01 before flight). The calculation of this index is based on the ratio oh TW-alternations and normalized with respect to HR-variation of RR-interval. The indicator of TW-alternations during flight does not change. All these changes of autonomic regulation and of myocardium bioelectricall properties during space flight were more pronounced and occurred earlier (from the first month of flight) during night period. The circadian rhythms of HRV during flight were smoothed in comparison with pre-flight data. Conclusion. The role of reduced RR-variations in maintaining of electrical stability of the myocardium needs further investigation. The amplitude of circadian rhythms is important for assessing the functional conditions of crew-members. A smoothing of circadian rhythms is a prognostic sign, evidence of the adaptation mechanisms violation during space flight.
- Abstract document
- Manuscript document
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