Ekologiya cheloveka (Human Ecology)Ekologiya cheloveka (Human Ecology)1728-08692949-1444Eco-Vector7160310.17816/humeco71603Research ArticleVariations of human heart bioelectrical signals at hypoxic exposureBocharovMihail I.<p>MD, Dr. Sci. (Biol.), professor</p>bocha48@mail.ruhttps://orcid.org/0000-0001-6918-5523ShilovAleksandr S.shelove@list.ruhttps://orcid.org/0000-0002-0520-581XKomi science centre of the Ural branch of the Russian academy of sciences010720222931751851606202118022022Copyright © 2022, Bocharov M.I., Shilov A.S.2022<p><strong><em>BACKGROUND:</em></strong> In the area of physiology and medicine, special emphasis is placed on the study of hypoxic conditions. Hypoxic responses of some major physiological systems, including blood circulation, are described. However, the cardiological component of these individual responses, and their variability at different levels of acute hypoxia (AH) remains a poorly-studied aspect.</p>
<p><strong><em>AIM:</em></strong> To study the individual characteristics of the response types in conjugated ECG parameters, and their variations at different stages of mild and medium AH.</p>
<p><strong><em>MATERIAL AND METHODS:</em></strong> The experiments were performed on male subjects (1826 years old) divided into two groups (<em>n</em><sub>1</sub>=30 and <em>n</em><sub>2</sub>=29), who were exposed to AH of 14.5% at 12.3% O<sub>2 </sub>for 20 min. Amplitude (<em>P</em><sub>1</sub>II, <em>R</em>II, <em>T</em><sub>1</sub>II, BA<sub>L</sub>, BA<sub>R</sub>) and temporal (<em>RR, QT</em>) ECG parameters, and blood oxygenation (SpO<sub>2</sub>) were determined at AH periods (at 5, 10, and 20 min respectively). In subgroups (clusters), the features of types with low and high responses, and their stability in AH are described.</p>
<p><strong><em>RESULTS:</em></strong> Clustering of ECG variations with AH of 14.5% and 12.3% O<sub>2 </sub>identified two subgroups (clusters), that differed at least in the magnitude of the decrease in the total BA<sub>L</sub> and <em>RR</em>. With AH of 14.5% O<sub>2</sub>, the number of different ECG parameters between subgroups gradually increased: at 5 min BA<sub>L</sub> (<em>p</em> 0.001), at 20 min <em>R</em>II (<em>p</em>=0.047), <em>T</em><sub>1</sub>II (<em>p</em>=0.016), BA<sub>L</sub> (<em>p</em> 0.001), <em>RR </em>(<em>p</em>=0.035), <em>QT</em> (<em>p</em>=0.008), and with AH 12.3% O<sub>2</sub> only BA<sub>L</sub> (<em>p</em> 0.001). It was found that at all periods of AH of 14.5% O<sub>2,</sub> in 60% of individuals, the type of response remained. Regarding AH of 12.3% O<sub>2</sub> in 55.2% of the other cases, the type of response of ECG parameters changed. At the same time, no parallels were observed between the types of reactions and deviations in SрO<sub>2</sub>.</p>
<p><strong><em>CONCLUSION:</em></strong> From this study, It can be assumed that there are two types of conjugated reactions of ECG parameters in response to mild and medium AH, and their variability is absent in 40% and 44.8% of cases, respectively, as well as the independence of differentiation of ECG responses types from hypoxemia.</p>humanacute hypoxiablood oxygenationelectrocardiographyчеловекострая гипоксияоксигенация кровиэлектрокардиография[Lukyanova LD. Signaling mechanisms of hypoxia. Moscow: RAS, 2019. (In Russ).][Newsholme P, De Bittencourt PIH, O’Hagan C, et al. Exercise and possible molecular mechanisms of protection from vascular disease and diabetes: the central role of ROS and nitric oxide. Clin Sci (Lond). 2009;118(5):341–349. doi: 10.1042/CS20090433][Semenza GL. Hypoxia-inducible factors in physiology and medicine. Cell. 2012;148(3):399–408. doi: 10.1016/j.cell.2012.01.021][Nesterov SV. Autonomic regulation of the heart rate in humans under conditions of acute experimental hypoxia. Human Physiology. 2005;(31)1:70–74. (In Russ). doi: 10.1007/s10747-005-0010-7][Boos CJ, Vincent E, Mellor A, et al. The effect of sex on heart rate variability at high altitude. Med Sci Sports Exerc. 2017;(49)12:2562–2569. doi: 10.1249/MSS.0000000000001384][Giles D, Kelly J, Draper N. Alterations in autonomic cardiac modulation in response to normobaric hypoxia. Eur J Sport Sci. 2016;16(8):1023–1031. doi: 1023–1031. doi: 10.1080/17461391.2016.1207708][Li Y, Li J, Liu J, et al. Variations of time irreversibility of heart rate variability under normobaric hypoxic exposure. Front Physiol. 2021;12:607356. doi: 10.3389/fphys.2021.607356][Uryumtsev DY, Gultyaeva VV, Zinchenko MI, et al. Effect of acute hypoxia on cardiorespiratory coherence in male runners. Front Physiol. 2020;11:630. doi: 10.3389/fphys.2020.00630][Lesova EM, Samoilov VO, Filippova EB, Savokina OV. Individual differences of hemodynamics in terms of hypoxia and orthostatic stress. Bulletin of the Russian Military medical academy. 2015;(49)1:157–163. (In Russ).][Sanotskaya NV, Matsievsky DD, Lebedeva MA. Acute hypoxia influence on pulmonary and systemic blood circulation. Pathogenesis. 2012;(10)4:56–59. (In Russ).][Coustet B, Lhuissier FJ, Vincent R, et. al. Electrocardiographic changes during exercise in acute hypoxia and susceptibility to severe high-altitude Illnesses. Circulation. 2015;(131)9:786–794. dol: 10.1161/CIRCULATIONAHA.114.013144][Novikov VS, Soroko SI, Shustov EB. Desadaptation states of man to exposure to extreme сonditions and their correction. Sankt-Peterbursburg. Politekhnika-print, 2018. (In Russ).][Malkin VB, Gippenreiter EB. Acute and chronic hypoxia. Moscow: Nauka, 1977. (In Russ).][Agadzhanyan NA, Mirrakhimov MM. Mountains and body resistance. Moscow: Nauka, 1970. (In Russ).][Bocharov MI, Shilov AS. Bioelectric heart processes in healthy men at different levels of acute normobaric hypoxia. Ekologiya cheloveka (Human Ecology). 2020;(27)12:28–36. (In Russ). doi: 10.33396/1728-0869-2020-12-28-36][Volkov NI. Intermittent hypoxia — a new method of training, rehabilitation, and therapy. Theory and practice of physical culture. 2000;(7):20–23. (In Russ).][Navarrete-Opazo А, Mitchell GS. Therapeutic potential of intermittent hypoxia: a matter of dose. Am J Physiol Regul Integr Comp Physiol. 2014;(307)10:R1181–R1197. doi: 10.1152/ajpregu.00208.2014][Instrumental methods for the study of the cardiovascular system: a reference. Vinogradova TS, editors. Moscow: Meditsina, 1986. (In Russ).][Turbasov VD, Artamonova NP, Nechaeva EI. Assessment of the bioelectrical activity of the heart in conditions of antiorthostatic hypokinesia using conventional and corrected orthogonal ECG leads. Space biology and aerospace medicine. 1990;(24)1:42–44. (In Russ).][Koichubekov BK, Sorokina MA, Mkhitaryan KE. Sample size determination in planning of scientific research. International Journal of applied and fundamental research. 2014;4:71–74. (In Russ).][Millet GP, Faiss R, Pialoux V. Last word on point: counterpoint: hypobaric hypoxia induces different responses from normobaric hypoxia. J Appl Physiol (1985). 2012;112(10):1795. doi: 10.1152/japplphysiol.00338.2012][Vigo DE, Lloret SP, Videla AJ, et al. Heart rate nonlinear dynamics during sudden hypoxia at 8230 m simulated altitude. Wilderness Environ Med. 2010;21(1):4–10. doi: 10.1016/j.wem.2009.12.022][Li Y, Gao J, Lu Z, et al. Intracellular ATP binding is required to activate the slowly activating K+ channel IKs. Proc Natl Acad Sci U S A. 2013;110(47):18922–18927. doi: 10.1073/pnas.1315649110][Kane GC, Liu XK, Yamada S, et al. Cardiac KATP channels in health and disease. J Mol Cell Cardiol. 2005;(38)6:937–943. doi: 10.1016/j.yjmcc.2005.02.026][Anikina TA, Sitdikov FG. Purinoreceptors of the heart in ontogenesis. Kazan, Printing house of TGSPU. 2011. (In Russ).][Vassort G. Adenosine 5’-triphosphate: a P2-purinergic agonist in the myocardium. Physiol Rev. 2001;81(2):767–806. doi: 10.1152/physrev.2001.81.2.767][Burnstock G, Kind BF. Numbering of cloned P2 purinoceptors. Drug Development Research. 1996;(38)1:67–71. doi: 10.1002/(SICI)1098-2299(199605)38:1<67::AID-DDR9>3.0.CO;2-28.][Burnstock G. Purinergic signaling. Br J Pharmacol. 2006;(147)S1:S172–S187. doi: 10.1038/sj.bjp.07064229.][Pelleg A, Katchanov G, Xu J. Autonomic neural control of cardiac function: modulation by adenosine and adenosine 5'-triphosphate. Am J Cardiol. 1997;79(12A):11–14. doi: 10.1016/s0002-9149(9x)00257-5]