CHANGE IN ACTIVITY OF CENTRAL AND AUTONOMOUS CIRCUITS OF HEART RHYTHM REGULATION IN CASE OF DYSFUNCTION OF AIRWAYS

Doct of med. sciences, prof. A.L. Isakadze, doct. of biol. sciences, prof. G.G. Eliava,

prof. T.G. Tsintsadze, assoc. prof. L.S. Topuria

Tbilisi State Medical University

Georgian Technical University

Annotation: Statistical analysis of heart rhythm variability is widely used both in experimental and in clinical medicine.

In the given work, due to changes in respiratory function there were studied the processes of rearrangement of performance level of blood circulatory system, which are focused on maintenance of homeokinesis and which characterize system mechanisms.

Research showed that during disorder of natural nasal breathing under conditions of relative physiological rest takes place displacement of balance (equilibrium) of central and autonomous circuits of heart rhythm regulation, enhancement of slow periodicity and severity (expressiveness) of stochastic aperiodic influences, decrease of index of tension of regulatory systems, increase of index of functional status of heart.

Keywords: heart rhythm variability, nasal breathing, central and autonomous circuits, heart rhythm regulation

I. Introduction

Mathematical description of physiological processes makes possible not only quantitative, but also qualitative analysis of vital processes in body and its systems under influence of different environmental factors on it [1,7].

Mathematical analysis of heart rhythm is widely used both in experimental and in clinical researches [1, 2, 7, 8].

Processes of rearrangement of performance level of blood circulation system reflect not only the action of stress factors, but also characterize internal and intersystem mechanisms focused on maintenance of homeokinesis.

It is known that stress, which runs in three stages (alert stage, resistance stage, exhaustion stage) is a unity of non-specific response, which are based on neuroendocrinal and metabolic changes, which manifest themselves as general adaptation syndrome (Fig. 1).

Fig. 1. Stress factor’s action mechanisms

Homeokinesis abnormalities during stresses are preceded by disorders in regulation of function, which emerge as a result of tension, supertension and further depletion of adaptation mechanisms (Fig. 2).

Fig. 2. Influence of homeokinesis function disorder on different indices

of vital functions

Fig. 3. Method of study of different aspects of activity of regulatory systems

Regulation of body functions may be represented by three interrelated systems – cerebral cortex, system of hormonal-humoral regulation and vegetative nervous system (Fig. 3).

Different samples of RR intervals are used for acquisition of information on various changes in body of healthy and sick persons depending on assigned task.

Good correlation of mathematical-statistical indices of heart rhythm and hemodynamics indices is obtained in patients having arterial hypertension [2, 5, 6]. Obtained indices supplement clinical-postgenetic features of formation and course of arterial hypertension. Received indices testify the predominance of sympathetic activation of vegetative nervous system among patients having arterial hypertension and the superiority of central mechanism of regulation of heart rhythm variability over autonomous regulations. Excessive activation of sympathetic-adrenal system and decreased activity of parasympathetic regulation testify deadaptation processes in hypertensive patients with disorder of regulation both at the level of segmental (subcortical) and suprasegmental (nuclear) brain structures and decreased influence of cortical inhibition on them.

Based on abovementioned we set a task of study of processes of rearrangement of performance level of blood circulation system due to changes in respiratory function.

II. Problem setting.

Heart rhythm variability of humans was studied in our work. Study was conducted in healthy persons aged 19-20 years.

Goal of the work was a study of mathematical-statistical indices of heart rhythm in case of disorder of natural nasal breathing. Persons under test performed breathing under conditions of both nasal and mouth breathing. In case of mouth breathing nasal breathing has been turned off using soft nose clip. Study has been conducted under conditions of relative physiological dormancy. Both nasal and mouth breathing have been performed in seated position. For removal of stochastic fluctuations of measurement the persons under test took a course of preliminary adaptation to mouth breathing. Method of correlation rhythmography has been used for research. Registration of correlation rhythmography has been conducted with the use of rhythmocardioscope RKS-01.

Sample volume was 100 cardiocycles. Mode (М_о), mode amplitude (АМ_о) and variation range (ΔХ) have been determined. By means of special program there have been established integral indices of heart rhythm: index of tension (IT) of regulatory systems; index of functional status (IFS).

III. Results.

Research results testify that at nasal breathing takes place the change of heart rhythm variability. At mouth breathing occurs enhancement of aperiodic stochastic influence on heart rhythm.

At nasal-mouth breathing, in comparison with nasal breathing takes place elongation of longitudinal axis of correlation rhythmogram, i.e. slow periodicity becomes more expressed.

Similar dynamics of correlation rhythmogram is also observed in case of only mouth breathing: takes place elongation of not only longitudinal axis of correlation rhythmogram but also transverse axis of correlation rhythmogram.

Abovementioned changes in correlation rhythmogram obviously demonstrate that mouth breathing promotes both the increase of aperiodic stochastic influence on heart rhythm and enhancement of slow periodicity in heart rhythm.

Analysis of such statistical parameters of heart rhythm as the mode (М_о), mode amplitude (АМ_о) and variational range ΔХ, evidences that at mouth breathing takes place enhancement of heart rhythm variability (Table 1).

Table 1. Change in indices of variational pulsogram at nasal and mouth breathing

Indices	Nasal breathing	Mouth breathing	Statistical indicator of confidence level
Mode, Мо	0,79 ± 0,08	0,73 ± 0,02	P < 0,05
Mode amplitude АМо	37,5 ± 4,8	22,0 ± 4,1	P < 0,001
Variational range	0,135 ± 0,001	0,20 ± 0,0045	P < 0,05

Indices of variational pulsogram are statistically significantly changed (р<0,5) as follows (Table 1):

- value of mode amplitude is decreased;

- mode value is decreased;

- variational range is increased.

Index of tension of regulatory systems, which has negative correlation with the index of functional status of heart, under conditions of mouth breathing significantly decreases (p<0,05) by 26% in average (Fig. 4). Index of functional status of heart increases by 45,8% in average (Fig. 5).

IT

Fig. 4. Change in index of tension (IT) of regulatory systems at nasal (1)

and mouth (2) breathing

IFS

Fig. 5. Change in index of functional status of heart at nasal (1)

and mouth (2) breathing

Abovementioned changes are in accordance with hemodynamic researches.

According to literature data [1,2,5,6], slow waves are related to adaptive activity of cardiovascular center.

Stochastic changes of venous inflow caused by the change in functional status of cardio-vascular system at mouth breathing lead to abovementioned changes of correlation rhythmogram. Changes in vegetative homeokinesis are related to increased influence of both sympathetic (relative gain of mode) and, predominantly, parasympathetic (enhancement of variational range, decrease in index of tension of regulatory systems) divisions of vegetative nervous system on sinoatrial node.

Change in vegetative homeokinesis may be explained by the fact that takes place the disorder of balance of central and autonomous circuits of heart rhythm regulation and, thereby, character of heart rhythm regulation. It seems that these phenomena may be explained by change of sensory input (afferent signalization) from airways under conditions of different pattern of breathing [3, 4].

Research results give us an opportunity to suppose that extracardiac effects, implemented from airways play significant role in multistage system of heart rhythm control.

IV. Conclusions:

Under conditions of mouth breathing the influence of autonomous circuit of heart rhythm regulation prevails.

1. Vegetative homeokinesis of heart rhythm regulation is changed in case of disorder of natural nasal breathing. Balance of central and autonomous circuits of heart rhythm regulation is disrupted.

2. Under conditions of mouth breathing is increased the severity (expressiveness) of slow periodicity with simultaneous enhancement of stochastic periodical effects.

3. Obtained data must be taken into account during assessment of heart rhythm of patients with dysfunctions of upper respiratory airways for delivery of adequate therapy.

References

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