NATURAL SCIENCES

Journal of fundamental
and
applied researches

Electrocardiographic characteristics of the heart of practically healthy people during passive antiorthostasis

2018. №2, pp. 38-43

Panteleeva N.I. - Ph.D. (Biology), Komi Science Center of the Ural Branch of the RAS, 24 Kommunisticheskaya St., Syktyvkar, 167982, Russian Federation, bdr13@mail.ru

Zamenina E.V. - Researcher, Komi Science Center of the Ural Branch of the RAS, 24 Kommunisticheskaya St., Syktyvkar, 167982, Russian Federation, e.mateva@mail.ru

Ulyasheva E.A. - postgraduate student, Komi Science Center of the Ural Branch of the RAS, 24 Kommunisticheskaya St., Syktyvkar, 167982, Russian Federation, evgeneka@mail.ru

The study of the influence of the change in the human body position in space and the redistribution of body fluids is topical in theoretical and practical aspects of human physiology. Such studies allow to evaluate the adequacy of compensatory and adaptive reactions of the organism, neurohumoral regulation of main functional systems, where the cardiovascular system plays a major role. The compensatory mechanisms of the organism normalize homeostatic changes by regulating heart beats and vascular tone. Because of a high sensitivity of the heart to changes in the volume of incoming blood (myocardium preload), it is important to understand the relationship between electrical and mechanical components of cardiac activity. To assess the effect of an increased preload on the electrical activity of the human heart an electrocardiographic study of the myocardium has been carried out in practically healthy young men under conditions of antiorthostasis. The ECG was recorded in the initial state, when changing the body position, during a 20-minute period in a supine position at an angle of 30В°, when descending, and during a 5-minute recovery. It was found that an increase in venous return to the right chambers of the heart led to a change in the P- and T-waves amplitudes in precordial leads and the prolongation of the PQ, QT, STT intervals. A negative chronotropic effect was observed as the time period of antiorthostasis increased, that was not, however, connected with the phase of the cardiac cycle - the QTc interval did not change significantly during the whole examination. The changes revealed are linked with the factors influencing the actual electrical activity of the myocardium (stretching of cardiomyocytes) and the transfer of an electrical signal to the recording electrodes (an increase in the intercardiac blood volume).

Key words: электрическая активность сердца, антиортостатическая проба, преднагрузка, правые отделы сердца, растяжение кардиомиоцитов, electrical activity of the heart, antiorthostatic test, preload, right chambers of the heart, stretching of cardiomyocites

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