As known, human cardiovascular system is a unique phenomenon. The most important organ is the heart muscle, which generates its own electrical impulses. Under the action of these impulses, muscle contraction occurs, which sets the rhythm and direction of blood flow. This is a kind of pump, ”embedded in the body by nature itself.

In addition to the heart muscle, the system also includes other components - the aorta (the largest artery), as well as smaller arterial and venous vessels and capillaries. If the state of health has worsened, it is quite possible that one of the components is “to blame”.

The main features of the cardiovascular system

Physicians identify some features of the cardiovascular system adult person:

• The heart is not a single integral organ; it consists of four divided departments - two in each half. Each of the halves includes an atrium and a ventricle, performing their own functions;
• The interatrial wall serves as a partition between the halves, its purpose is to distinguish between blood flows: for the arterial (coming from the lungs) - the left half, for the venous (with decay products coming from the tissues) - the right;
• The delimiter between the two parts (atria and ventricles) are special valves - on the left is the mitral valve (with 2 valves), on the right - with 3 valves;
• The movement of blood is possible only in one direction - from the atrium to the ventricle;
• If we compare the muscle layer in terms of contraction strength, it will be the most powerful in the left half, since it is responsible for a larger blood circulation cycle;
• The source of generated electrical impulses is the cardiac conduction system, which includes the sinoatrial (pacemaker) and atrioventricular (ventricular) nodes;
• The work of the heart is controlled by two more systems - hormonal and nervous.

Basic functions of the cardiovascular system

As noted by numerous articles on health, the human heart and blood vessels form a single closed system through which blood moves. Together with blood, nutrients and oxygen enter all organs and tissues - for metabolic processes, and processed substances are excreted. Certain tasks are assigned to the heart and blood vessels. Failure to comply with them leads to malaise and various diseases.

Main functions of the cardiovascular system are as follows:

• transportation of nutrients, carbon dioxide and oxygen, as well as the removal of metabolic products from tissues and cells;
• integration (the vascular system covers the entire body and unites it into a single whole);
• regulation - implies an independent change in the volume of blood entering certain organs, the delivery of hormones;
• participation in other processes occurring in the body (inflammatory, immune, etc.).

Some pathologies that are not directly related to the heart (for example, dysfunction of the thyroid gland, etc.) subsequently negatively affect its work.

The human body has its own individual development from the moment of fertilization to the natural end of life. This period is called ontogeny. It distinguishes two independent stages: prenatal (from the moment of conception to the moment of birth) and postnatal (from the moment of birth to the death of a person). Each of these stages has its own characteristics in the structure and functioning of the circulatory system. I will consider some of them:

Age features in the prenatal stage. The formation of the embryonic heart begins from the 2nd week of prenatal development, and its development in general terms ends by the end of the 3rd week. The blood circulation of the fetus has its own characteristics, primarily due to the fact that before birth, oxygen enters the body of the fetus through the placenta and the so-called umbilical vein.

The umbilical vein branches into two vessels, one feeding the liver, the other connected to the inferior vena cava. As a result, oxygen-rich blood mixes with blood that has passed through the liver and contains metabolic products in the inferior vena cava. Through the inferior vena cava, blood enters the right atrium.

Further, the blood passes into the right ventricle and then is pushed into the pulmonary artery; a smaller part of the blood flows into the lungs, and most of the blood enters the aorta through the ductus arteriosus. The presence of the ductus arteriosus, which connects the artery to the aorta, is the second specific feature in the fetal circulation. As a result of the connection of the pulmonary artery and the aorta, both ventricles of the heart pump blood into the systemic circulation. Blood with metabolic products returns to the mother's body through the umbilical arteries and the placenta.

Thus, the circulation in the body of the fetus of mixed blood, its connection through the placenta with the mother's circulatory system and the presence of the ductus botulinum are the main features of the fetal circulation.

Age features in the postnatal stage. In a newborn child, the connection with the mother's body is terminated and his own circulatory system takes over all the necessary functions. The ductus botulinum loses its functional significance and soon becomes overgrown with connective tissue. In children, the relative mass of the heart and the total lumen of the vessels are greater than in adults, which greatly facilitates the processes of blood circulation.

Are there patterns in the growth of the heart? It can be noted that the growth of the heart is closely related to the overall growth of the body. The most intensive growth of the heart is observed in the first years of development and at the end of adolescence.

The shape and position of the heart in the chest also changes. In newborns, the heart is spherical and located much higher than in an adult. These differences are eliminated only by the age of 10.

Functional differences in the cardiovascular system of children and adolescents persist up to 12 years. The heart rate in children is higher than in adults. Heart rate in children is more susceptible to external influences: physical exercise, emotional stress, etc. Blood pressure in children is lower than in adults. Stroke volume in children is much less than in adults. With age, the minute volume of blood increases, which provides the heart with adaptive opportunities for physical activity.

During puberty, the rapid processes of growth and development occurring in the body affect the internal organs and, especially, the cardiovascular system. At this age, there is a discrepancy between the size of the heart and the diameter of the blood vessels. With the rapid growth of the heart, the blood vessels grow more slowly, their lumen is not wide enough, and in connection with this, the adolescent's heart bears an additional load, pushing blood through narrow vessels. For the same reason, a teenager may have a temporary malnutrition of the heart muscle, increased fatigue, easy shortness of breath, discomfort in the region of the heart.

Another feature of the cardiovascular system of a teenager is that the heart of a teenager grows very quickly, and the development of the nervous apparatus that regulates the work of the heart does not keep up with it. As a result, adolescents sometimes experience palpitations, abnormal heart rhythms, and the like. All of these changes are temporary and arise in connection with the peculiarity of growth and development, and not as a result of the disease.

Hygiene SSS. For the normal development of the heart and its activity, it is extremely important to exclude excessive physical and mental stress that disrupts the normal pace of the heart, and also to ensure its training through rational and accessible physical exercises for children.

Training of cardiovascular activity is achieved by daily physical exercises, sports activities and moderate physical labor, especially when they are carried out in the fresh air.

The hygiene of the circulatory organs in children imposes certain requirements on their clothing. Tight clothing and tight dresses compress the chest. Narrow collars compress the blood vessels of the neck, which affects the blood circulation in the brain. Tight belts compress the blood vessels of the abdominal cavity and thereby impede blood circulation in the circulatory organs. Tight shoes adversely affect blood circulation in the lower extremities.

heart circulation hypertrophy

Features of the cardiovascular system in puberty
In the pubertal period, the growth of various organs and systems occurs with unequal intensity, which often leads to temporary disturbances in the coordination of their functions. This applies primarily to the cardiovascular system. So, during this period, there is a lagging of the volume of the heart from the volume of the body. If in an adult the ratio of heart volume to body volume is 1:60, in a teenager it is 1:90. It has also been established that if the volume of the heart of adolescents clearly correlates with height and body weight, there is no such correlation with the diameter of large vessels (Kalyuzhnaya R.A., 1975). Consequently, the adolescent period is characterized by an increase in the volume of the heart ahead of the increase in the lumen of large vessels. This is one of the important factors contributing to the increase in blood pressure and the appearance of systolic murmur during puberty.

Different intensity of growth is also observed on the part of the muscular and nervous tissue of the myocardium, since the growth of the nervous tissue lags far behind the rapidly growing mass of the myocardium, which can cause temporary disturbances in rhythm and conduction.

During this period, the coronary arteries grow, their lumen increases, which contributes to good vascularization of the heart and the growth of myocardial muscle cells.

Growth, development and functional improvement of the cardiovascular system is completed only by the age of 19-20. By this time, the main hemodynamic parameters become the same as in adults. Harmoniously developed adolescents have a high correlation of the volume of the heart and the diameter of the main vessels with body size, combined with a good functional state of the cardiovascular system.

In the pubertal period, gender differences begin to be clearly manifested, concerning both the mass of the heart and the functional state of the cardiovascular system and physical performance. In boys at the age of 17, the stroke volume of the heart is greater, the functional state of the cardiovascular system and adaptation to physical activity are better compared to girls (Berenstein A. G. et al., 1987; Farber D. A. et al., 1988).

In 6.5% of cases, there are deviations in the process of age-related evolution of the cardiovascular system towards hypoevolution or hyperevolution of the heart (Kalyuzhnaya R.A., 1975).

Hypoevolution of the heart, i.e. lagging behind the normal dynamics of development, includes two morphological variants: a small hypoevolutionary heart and a hypoevolutionary heart of a mitral configuration. Juvenile myocardial hypertrophy belongs to the hyperevolution of the heart.

A small hypoevolutionary heart is characterized by small size and occurs mainly in tall adolescents with a lack of body weight, with long limbs and a narrow chest. These adolescents usually complain of an asthenovegetative nature: palpitations, shortness of breath, weakness, fatigue, pain in the region of the heart, fainting, etc. others

The hypoevolutionary heart of the mitral configuration is observed in those cases when the turn of the heart forward and to the left has not been completed. Therefore, although the size of the heart is normal, on the frontal radiograph it has a mitral configuration due to the arch of the pulmonary artery, which extends beyond the left contour of the heart at the waist. Adolescents with such a heart, as a rule, do not complain. However, this variant of the hypoevolutionary heart is considered an extreme variant of physiological development (Medvedev V.P., 1990).

Juvenile hypertrophy of the heart is usually observed in adolescents with harmonious development, especially those involved in physical culture and sports. Such a heart has good indicators of the functional state.

The pubertal period is characterized by active hormonal changes in the body and improvement in the function of the autonomic nervous system (ANS). In this period, neuroendocrine disorders often occur with the development of autonomic dysfunction. These disorders, as a rule, disappear by the end of puberty, but in some cases they are the basis for the development of such diseases as neurocirculatory dystonia (asthenia) and hypertension.

At the age of 16–17 years, there is an uneconomical function of the circulatory system, especially in girls. The minute volume of blood in young men exceeds the proper values ​​by 28–35%, and in girls - by 37–42% (Berenshtein A.G., 1987). This explains the low physical performance in 60% of cases in untrained adolescents (Tashmatova R. Yu. et al., 1988).

In adolescents, as well as in adults, there are three types of hemodynamics, which are determined by the cardiac index - SI (Table 2.1).

In most cases (50–60%), healthy adolescents have a eukinetic type of hemodynamics.

Table 2.1 Determining the type of hemodynamics in adolescents depending on the cardiac index (l / min * m2) Types of hemodynamics Gender
boys girls
Hypokinetic 3.0 or less 2.5 or less
Eukinetic 3.1–3.9 2.6–3.5
Hyperkinetic 4.0 or more 3.6 or more

2.1.1. Objective Research Data

When examining the region of the heart and large vessels, one can often see an apex beat in the 5th intercostal space 0.5–1.0 cm medially from the midclavicular line. The visualization of the apex beat in adolescents is due to the thin chest, often the pulsation of the carotid arteries is also clearly visible, especially with the sympathicotonic type of autonomic regulation.

On palpation, the apical and cardiac impulses are not increased, the pulse is of normal filling and tension. At rest, with the normotonic type of autonomic regulation, the pulse rate ranges from 65 to 85 beats / min, vagotonic and sympathicotonic types, its frequency is less than 65 and more than 85 beats / min, respectively. However, lability of the pulse can be noted during the day, mainly in adolescents with autonomic dysfunction.

On percussion. Borders of relative cardiac dullness are usually normal. With a small hypoevolutionary heart, they are reduced, and with juvenile hypertrophy, the left border of the heart does not go beyond the midclavicular line in the fifth intercostal space.

On auscultation, the 1st tone at the apex is either normal or intensified. Strengthening of the I tone at the apex is observed in adolescents with a thin chest and a sympathicotonic type of autonomic regulation. Physiological splitting of the I tone is rare and is associated with asynchronous slamming of the mitral and tricuspid valves; this splitting is heard inconsistently and depends on the phases of respiration. On the basis of the heart, physiological splitting of the II tone is often heard, which is observed during the asynchronous end of the systole of the right and left ventricles with a relative narrowness of the aorta or pulmonary artery. This splitting of the II tone is of a non-permanent nature and completely disappears by the end of the pubertal period. Accent II tone over the pulmonary artery can be observed with its relative narrowness and also disappears by the end of puberty.

In more than half of adolescents at the apex and at the Botkin point, immediately after the II tone, a physiological III tone is heard, which occurs due to the vibration of the ventricles during their rapid filling in the protodiastole. III tone usually sounds muffled tone II, due to the predominance of low frequencies in its sound.

Standing and during physical activity III tone, as a rule, disappears. The physiological IV tone is rare and is perceived by auscultation as a bifurcation of the I tone, since it occurs in the presystole immediately before the I tone. Its appearance is associated with increased atrial systole, which is why it is called atrial. IV tone is more common in vagotonics in the presence of bradycardia. Apparently, an increase in blood supply to the atria during bradycardia causes an increase in their systole. IV tone, as well as III, disappears in a standing position, during and after exercise.

It should be borne in mind that III and IV tones can be pathological and occur in patients with various diseases of the cardiovascular system. Therefore, in these cases, differential diagnosis between the physiological and pathological genesis of additional tones is important.

In healthy adolescents, a systolic murmur is often heard with localization in the region of the apex of the heart and along the left edge of the sternum (50-60%). It is soft, short in sound, significantly decreases or disappears in a standing position and intensifies after physical exertion. The genesis of noise can be different - this is an increase in blood flow as a result of a relative narrowing of the lumen of the main vessels, dysfunction of papillary muscles with a sympathicotonic type of autonomic regulation, the presence of false chords, etc. In most adolescents, by the end of puberty, systolic murmur disappears. Noise persists in the presence of an anomaly in the development of the valvular apparatus and subvalvular structures of the heart.

Auscultation of the heart reveals respiratory arrhythmia in almost all adolescents. This arrhythmia becomes especially pronounced if the teenager is asked to breathe slowly and deeply. At the same time, on inhalation, the rhythm quickens; on exhalation, it slows down due to an increase in the inhibitory effect of the vagus nerve on the heart rhythm at the moment of exhalation.

BP in adolescents depends on gender, age and somatotype (Table 2.2). BP numbers between the 3rd and 90th centile indicate normal blood pressure, between 90 and 97 indicate borderline arterial hypertension, and values ​​above the 97th centile indicate arterial hypertension.

Somatotype and age (years) Systolic BP, centiles Diastolic BP, centiles
3 90 97 3 90 97
boys
microsomatic type
11–13 76 110 114 34 67 72
14-15 82 112 116 34 68 74
16–17 90 118 124 36 74 78
Mesosomatic type
11–13 80 111 118 35 66 72
14–15 86 120 120 35 68 80
16–17 94 130 130 38 76 84
macrosomatic type
11–13 84 121 132 36 72 80
14–15 96 126 136 36 74 80
16–17 98 139 154 38 80 84
Girls
microsomatic type
10–11 75 111 119 34 67 70
12–13 82 114 124 34 67 70
14–15 85 120 128 36 74 80
16–17 85 122 128 37 77 84
Mesosomatic type
10–11 76 111 120 34 67 72
12–13 84 114 126 36 71 78
14–15 86 120 130 44 75 80
16–17 86 122 130 46 78 84
macrosomatic type
10–11 82 118 126 38 71 76
12–13 85 123 128 38 72 80
14–15 90 126 132 46 78 82
16–17 90 129 136 48 82 87

2.1.2. Data of instrumental research methods

After a physical examination of a teenager, it is often necessary to resort to instrumental diagnostics, especially in cases where a teenager makes certain complaints about the cardiovascular system, a hypoevolutionary heart or juvenile myocardial hypertrophy is suspected, additional tones, systolic murmur, etc. are heard.

In these cases, it is necessary to carry out differential diagnostics between the characteristics of the cardiovascular system of a teenager and diseases, as well as pre-pathological conditions that can occur secretly. For this purpose, first of all, chest X-ray, electrocardiography (ECG), echocardiography (EchoCG), etc. are used.

2.1.2.1. Chest X-ray. In healthy adolescents aged 16–17 years, with a normal evolution and a normal configuration of the heart, all the arcs are well expressed, and the diameter of the heart is at least 11 cm.

A small hypoevolutionary heart is characterized by its median position, narrowness of the cardiac shadow (diameter of the heart 8.5–9.5 cm) and lengthening of the cardiac arches. If a small hypoevolutionary heart is combined with a protrusion of the pulmonary artery arch, it acquires a mitral configuration due to the flattening of the cardiac waist. In the latter case, it is necessary to carry out a differential diagnosis with mitral heart disease, which requires a comprehensive assessment of clinical and diagnostic data.

With juvenile myocardial hypertrophy, an increase in the left ventricle is observed, the roundness of its apex, the transverse size of the heart is increased to 12–14 cm.

At puberty, single-born children in cardiometric parameters are ahead of their peers from mono- and dizygotic twin pairs (Kukhar I.D., Kogan B.N., 1988).

2.1.2.2. Electrocardiography. The ECG of adolescents approaches the ECG of adults, but has a number of characteristic features. These include severe sinus (respiratory) arrhythmia and shorter intervals compared to adults. Thus, the duration of the PQ interval is 0.14–0.18 s, the duration of the QRS complex is 0.06–0.08 s, the electrical systole of the ventricles, depending on the heart rate, is 0.28–0.39 s.

Most adolescents have a semi-vertical or intermediate position of the heart, less often vertical, semi-horizontal and horizontal (Oskolkova M. K., Kupriyanova O. O., 1986; Sarana V. A. et al., 1989).

The P wave in I and II standard leads is positive, and the ratio of the height of the P wave to the height of the T wave in these leads is 1:8–1:10, the duration of the P wave ranges from 0.05 to 0.10 s (average 0.08 With). In standard lead III, the P wave may be flattened, biphasic, or negative. In the AVL lead, the P wave is often biphasic or inverted in vertical and semi-vertical positions of the heart. In the right chest leads (V1-2), the P wave may be pointed, flattened, or negative.

The QRS complex is often polyphasic in standard lead III (in the form of the letter M or W). In the right chest leads, the amplitude of the S wave predominates, and in the left - the R wave, the transition zone of the QRS complex is more often in lead V3. Serrated S or R wave may be seen in lead V1-2 with normal QRS complex duration and internal deflection time. Such changes are characteristic of the syndrome of delayed excitation of the right supraventricular crest and are a variant of the norm. This syndrome occurs in adolescents in 20–24% of cases, and in adolescents involved in sports - up to 35.5% (Sarana V. A. et al., 1989; Kozmin-Sokolov N. B., 1989; Dembo A. G ., Zemtsovsky E. V., 1989). In adolescents with a thin chest, high amplitude QRS waves are often recorded in the chest leads. In these cases, the Sokolov-Lyon Sv1 + Rv5 index of 35 mm or more, which is characteristic of left ventricular hypertrophy, may turn out to be positive.

The ST segment in all leads is on the isoelectric line, its displacement by 1–2 mm above the isoline is observed mainly in the chest leads from V2 to V4 in adolescents with a vagotonic type of autonomic regulation.

An oblique-ascending ST segment depression can be observed both in standard and chest leads in adolescents with a sympathicotonic type of autonomic regulation against the background of tachycardia.

The T wave can be flattened, biphasic or negative in lead V1 less often than V2, as well as in standard lead III, while it must be positive in lead AVF. If the T wave in III and AVF leads is negative, this indicates a violation of the repolarization process in the region of the posterior wall of the left ventricle. With a vertical and semi-vertical position of the heart, a negative T wave is often observed in the AVL lead, which is a variant of the norm.

The U wave is recorded immediately after the T wave, more often in the chest leads (V2-4) and occurs in 70% of healthy adolescents (Medvedev V.P. et al., 1990). This wave reflects the repolarization of the papillary muscles, normally it is positive, but in amplitude it is much smaller than the T wave.

Of the cardiac arrhythmias in adolescents, the most common are sinus arrhythmia, as well as sinus tachycardia and bradycardia, respectively, with sympathicotonic and vagotonic types of autonomic regulation. A variant of the norm is the migration of the pacemaker through the atria, which is more often observed in adolescents with autonomic dysfunction. At the same time, in the standard and enhanced leads from the limbs, a P wave of different amplitude and duration is recorded, and the PQ and RR intervals can also be different in duration.

The syndrome of early repolarization of the ventricles (ERVR) often occurs in the prepubertal and pubertal periods (Oskolkova M.K., Kupriyanova O.O., 1986). This syndrome is characterized by elevation of the ST segment with a bulge directed downwards, the presence of a j point (a notch or connection wave on the descending knee of the R wave or the ascending knee of the S wave), and the rotation of the electrical axis of the heart counterclockwise around the longitudinal axis. These changes are especially clearly recorded in the chest leads. There are many hypotheses of the electrophysiological substantiation of RRS. The most proven point of view is that SRW occurs as a result of the imposition of a vector of delayed depolarization of individual sections of the myocardium on the initial repolarization phase of the ventricles (Storozhakov G. I. et al., 1992; Mirwis D. M. et al., 1982). SRRJ can be both a variant of the norm and a manifestation of various diseases of the cardiovascular system (Skorobogaty A. M. et al., 1990; Storozhakov G. I. et al., 1992). This syndrome is often found in primary connective tissue dysplasia (funnel chest deformity, mitral valve prolapse, false chords of the left ventricle, etc.); hypertrophic cardiomyopathy, accessory atrioventricular pathways, autonomic dysfunction, electrolyte disturbances, etc. Therefore, the identification of SRW requires the exclusion of diseases of the cardiovascular system (Vorobiev L.P. et al., 1991).

Physical activity (veloergometry) in healthy adolescents gives the following ECG changes. Against the background of an increase in heart rate to submaximal age values ​​(150-170 beats / min), there is a moderate increase in the voltage of the P wave, a decrease in the R wave, a decrease or increase in the T wave, the ST segment either remains on the isoline, or its ascending depression is noted, but not more than 1.5 mm. Such ECG changes during physical activity are detected in 60-65% of adolescents (Sarana V.A. et al., 1989).

2.1.2.3. Echocardiography. The main morphofunctional EchoCG parameters in healthy adolescents approach those of an adult and depend on the somatotype. At the age of 15-17 years, the diameter of the cavity of the left ventricle in diastole is 43-46 mm, in systole 28-32 mm, the final diastolic volume of the left ventricle is 106-112 ml, systolic - 26-30 ml. The thickness of the posterior wall of the left ventricle and interventricular septum is 8–10 mm. The diameter of the cavity of the right ventricle in diastole ranges from 12–14 mm, and that of the left atrium, 24–26 mm.

An echocardiogram study should definitely be carried out in adolescents who have auscultated systolic murmur.

In recent years, it has been shown that in healthy adolescents with the presence of systolic murmur, echocardiography in most cases reveals various ventriculoseptal, chordal, papillary features of the intracardiac structure, as well as positional features of the chambers of the heart and its main vessels. The most common are: false chords of the left ventricle and movable chord of the mitral valve, displacement of the papillary muscles and their splitting, additional papillary muscle, pronounced trabecularity of the ventricular cavity, etc. Among healthy adolescents with systolic murmur in 35.5% of cases, there is a combination of these anomalies, which causes a complex mechanism of noise formation with the participation of both "ejection noise" and "regurgitation noise". The hyperkinetic type of hemodynamics is a resolving factor for the appearance of noise.

Such features of the intracardiac structure (small anomalies) often proceed favorably and do not reduce the functional state of the cardiovascular system. However, in a number of cases, adolescents begin to complain of pain in the region of the heart, interruptions, palpitations, etc., which requires a more detailed examination and treatment.

2.1.2.4. Rhythmographic study. The imperfection of neurohormonal regulation, characteristic of the puberty period, can lead to the development of autonomic dysfunction and disruption of the body's adaptation to the environment. This, in turn, contributes to the occurrence of diseases of the cardiovascular system (NCA, hypertension, etc.).

The functional state of the ANS can be judged from the study of the respiratory periodicity of the heart rhythm, since during breathing there is a sequential inhibition and excitation of the nucleus of the vagus nerve, which is transmitted to the sinus node through the corresponding nerve endings. In this case, cardiointervals are shortened on inspiration and lengthened on expiration. Dosed breathing (6–7 respiratory cycles per 1 min) with normal vegetative regulation of the heart rhythm causes an increase in respiratory periodicity, i.e. shortening and lengthening of the duration of cardiointervals becomes more pronounced. With autonomic dysfunction, these patterns are violated.

One of the simple and reliable methods for studying the respiratory periodicity is the method of cardiointervalography (CIG), which is presented in the automated complex "Cardiometer" (produced by LLP "Micard"). Using this method, it is possible to assess the functional state of the ANS according to three parameters: vegetative tone (type of vegetative regulation), reactivity of the ANS departments and vegetative support of cardiac activity. At rest (after 15–20 minutes of rest) and at the time of the respiratory test (6–7 respiratory cycles per 1 min), 100 cardiocycles are recorded, according to which the following indicators of heart rate variability are automatically calculated: RRmax. - the maximum value of the intervals RR (c), RRmin. - minimum value of intervals RR (c), RRcp. - the average value of the intervals RR (c) and? RR - indicators of heart rate variability (the difference between RRmax. And RRmin. (c). The study should be carried out only in the morning.

The study of heart rate variability at rest allows you to determine the type of autonomic regulation (Baevsky R.M., 1979). With the normotonic type of vegetative regulation, the values ​​of RRavg. range from 0.70 to 0.90 s, and?RR - from 0.10 to 0.40 s, with vagotonic and sympathicotonic types, these indicators are, respectively: RRav. more than 0.90 s with? RR more than 0.40 s and RRavg. less than 0.70 s with?RR less than 0.10 s.

A breath test allows you to explore the response (reactivity) of the ANS to physiological influences. Depending on how much the increase in RRmax occurs. and decrease in RRmin. at the time of the test, compared with rest, the reactivity of the parasympathetic and sympathetic divisions of the ANS, respectively, is assessed (Levina L.I., Shcheglova L.V., 1996).

With normal reactivity of the parasympathetic and sympathetic divisions (PSO and SO) of the ANS, the indicators of an increase in RRmax. (?RRmax.) and decreasing RRmin. (?RRmin) are in the range from 0.05 to 0.10 s, and the vegetative provision of the sample is carried out at the expense of both sections of the ANS. With an increase in the reactivity (hyperreactivity) of PSO and (or) SO of the ANS, these indicators exceed 0.10 s, respectively, and the vegetative provision of the sample is excessive either due to one of the departments, or evenly excessive due to both departments of the ANS. With a decrease in reactivity (hyporeactivity) PSO and (or) CO VNS indicators? RRmax. and?RRmin are less than 0.05 s. This indicates a low vegetative supply of the sample either due to one of the departments, or it is evenly low due to both departments of the ANS. At the same time, paradoxical reactions can be determined, which are characterized by a decrease (instead of an increase) in the ?RRmax indicator. and (or) an increase (instead of a decrease) in the indicator? RRmin.

Depending on the state of reactivity of the parasympathetic and sympathetic divisions of the ANS, 5 types of vegetative support (VO) are distinguished in adolescents:

Normal uniform VO due to both departments of the ANS (increase? RR max. from 0.05 to 0.10 s, decrease? RR min. from 0.05 to 0.10 s);
excessive uniform VO due to both departments of the ANS (increase?RRmax. more than 0.10 s, decrease in RRmin more than 0.10 s);
low uniform VO from both departments of the ANS (increase?RRmax less than 0.05 s, decrease RRmin less than 0.05 s), paradoxical reactions;
VO mainly due to PSO ANS (increase? RRmax. from 0.05 to 0.10 s or more, decrease? RRmin less than 0.05 s or a paradoxical reaction);
VO is mainly due to SO VNS (decrease in RRmin by 0.05–0.10 s or more, increase in RRmax by less than 0.05 s or a paradoxical reaction).
Vegetative provision of cardiac activity can be normal, and also proceed with adaptation and maladjustment (Shcheglova L.V., 2002). Normal vegetative provision of cardiac activity is most often found in adolescents with a normotonic type of autonomic regulation and normal uniform VO due to both sections of the ANS (72.9%).

For vegetative support with adaptation, an increase in the activity (tonus) of one of the ANS departments is characteristic, which is accompanied by an increase in the reactivity of another department. This creates a dynamic vegetative balance, providing an adequate response of the heart rhythm in response to the physiological impact. So, with the vagotonic type of vegetative regulation, vegetative provision occurs due to the sympathetic division of the ANS, and with the sympathicotonic type, respectively, the parasympathetic. Such vegetative provision occurs in healthy adolescents in 20.3% of cases. Thus, the connection of compensatory mechanisms of regulation leads to the preservation of autonomic homeostasis, which creates an adequate response to physiological effects. Such reactions can be regarded as borderline, standing on the verge of norm and pathology.

With disadaptation of the vegetative supply (vegetative dysfunction), the dynamic balance is disturbed, since an increase in the activity (tonus) of one department is accompanied by an increase in the reactivity of the same department of the ANS. So, with the sympathicotonic type of autonomic regulation and autonomic supply due to the predominantly sympathetic section of the ANS, even more pronounced increase in heart rate occurs in response to physiological effects already with initial tachycardia. With the vagotonic type of autonomic regulation and autonomic supply due to the predominantly parasympathetic division of the ANS, in response to physiological influences, an inadequate increase in heart rate is observed. This indicates a violation of the adaptive-compensatory mechanisms of regulation of the circulatory system.

Uniformly high and uniformly low vegetative supply is also pathological and refers to disadaptation reactions. A uniformly high vegetative supply due to both sections of the ANS sharply increases the variation range and contributes to the appearance of heart rhythm disturbances (migration of the pacemaker, extrasystole). Therefore, this variant of vegetative provision is considered arrhythmogenic. With a uniformly low vegetative supply (vegetative insufficiency), there is a tendency to a rigid rhythm, while the adaptive-compensatory mechanisms of regulation of the circulatory system are significantly reduced. Disadaptation of autonomic provision in healthy adolescents is rare (6.8%).

Carrying out such studies will allow us to assess the functional state of the autonomic nervous system and identify violations of the adaptive-compensatory mechanisms of regulation of the circulatory system.

Knowledge of the characteristics of the cardiovascular system in adolescence enables the doctor to correctly interpret certain deviations and early identify pre-pathological conditions and diseases of the cardiovascular system. This will allow timely implementation of therapeutic and preventive measures, which will contribute to the improvement of the younger generation.

2.2. Neurocirculatory dystonia (asthenia)

L.I. Levina, L.V. Shcheglova, S.N. Ivanov

Definition. Neurocirculatory asthenia (NCA) is a syndrome of functional disorders of the cardiovascular system, which occurs as a result of inadequacy of nervous regulation. Nerve dysregulation can occur at any level of the cerebral cortex, subcortical deep structures, brainstem, and peripheral ganglia. These disorders lead to the development of autonomic dysfunction, which in turn causes the appearance of cardiovascular disorders.

In the 1950s, N. N. Savitsky introduced the term NCD into clinical practice to refer to a disease that occurs as a result of dystonia of the central nervous apparatus that regulates the function of blood circulation and proceeds according to the cardiac, hypo- and hypertensive type.

In the structure of diseases of the cardiovascular system in adolescents, 75% are autonomic disorders of cardiac activity (Levina L. I., 1994). According to the international classification of diseases ICD-10, these disorders are included in the heading of somatoform autonomic dysfunction. To designate somatoform autonomic dysfunction, occurring mainly with cardiovascular disorders, in our country the term proposed by N. N. Savitsky, “Neurocirculatory dystonia” (NCD), has been adopted. In the schedule of diseases of the Regulations on military medical examination No. 123, approved by the Decree of the Government of the Russian Federation of February 25, 2003, the term neurocirculatory asthenia is used.

NCA refers to functional diseases of the cardiovascular system, however, this concept is conditional, since it is known that dysfunction is always associated with structural changes that can occur at the cellular and subcellular levels and are not always detected using even modern research methods.

Prevalence. When examining adolescents aged 15 to 21 years, NCA is determined in 12.4% of cases, equally often in girls and boys (Antonova L. T. et al., 1989). In the structure of cardiovascular diseases, NCA occurs 3 times more often in adolescents compared to organic diseases - respectively: 75 and 25% (Levina L.I. et al., 1994).

Etiology and pathogenesis. According to the etiology, NCA can be primary and secondary. Primary NCA is an independent nosological form of the disease. Etiological factors in the development of primary NCA are neurosis, pubertal-adolescent and constitutional-hereditary autonomic dysfunction. The development of vegetative dysfunction is facilitated by the incompleteness of the morphological and functional formation of the central nervous system, which is characteristic of the pubertal period.

The works of F. Z. Meyerson et al. (1990) showed that in patients with NCA, there is an inferiority of physiological mechanisms that limit the stress response, and, as a result, an excessive increase in the adrenergic component of this reaction is observed. Indeed, in most adolescents with NCA, an increase in the reactivity of the sympathetic division of the ANS is determined.

Secondary NCA is a syndrome that occurs with various diseases and is often transient. In favorable cases, circulatory disorders are temporary and subside when the cause is eliminated or during the period of remission of the underlying disease. Diseases in adolescents, in which NCA most often develops, include (Nesterenko A. O. et al., 1994):

connective tissue dysplasia;
foci of chronic infection;
intoxication (including professional);
asthenic syndrome after infections, surgical interventions, injuries;
exposure to ionizing radiation, etc.
Among adolescents, primary and secondary NCA occurs with the same frequency. The most significant etiological factors in patients with primary NCA are neuroses (especially asthenovegetative neurosis), which occur in 34.7% of cases. Secondary NCA in adolescents most often develops with foci of chronic infection (especially chronic tonsillitis) in 40% of cases (L. I. Levina, L. V. Shcheglova, 1996).

It should be noted a number of unfavorable factors that predispose to NCA disease and worsen the course and prognosis. These factors primarily include smoking, alcohol and drug use, the frequency of which has increased significantly in recent years. Other adverse factors include underweight (16.6%) and menstrual irregularities in girls (20.8%), up to amenorrhea. The increase in the frequency of NCA is also associated with the low physical activity of adolescents, since most of them do not go in for physical culture and sports.

In the pathogenesis of NCA, the main role belongs to autonomic dysfunction, which causes a violation of the adaptation of the cardiovascular system to the effects of external and internal environmental factors. Such a failure of adaptation leads to the appearance of inadequate vascular reactions, disruption of cardiac activity and the activity of other internal organs.

Clinic. Diagnosing NCA is a very responsible and difficult task, since the doctor must completely exclude the organic pathology of the cardiovascular system. At the same time, inadequate examination of adolescents leads to the fact that serious organic diseases are often hidden under the flag of the NCA.

Thus, among patients admitted to the clinic with a diagnosis of NCA, in 65% of cases certain organic diseases of the cardiovascular system are detected.

Usually, the diagnosis of NCA is made in cases where there are complaints of pain in the region of the heart, headaches, palpitations, interruptions in the work of the heart, a feeling of "lack of air", lability of the pulse and blood pressure in the absence of cardiomegaly and heart failure. However, it is well known that many diseases of the cardiovascular system of an organic nature have a similar clinical picture, especially in the early stages of their development. In the presence of good compensatory capabilities of a young organism, these diseases can proceed for a long time without cardiomegaly and heart failure. Timely detection and early treatment of such diseases in adolescents makes it possible to stop their progression, and in some cases to achieve regression of the pathological process.

The clinical presentation of NCA is very variable and is characterized by polymorphism of symptoms. Some patients present only one complaint, for example, pain in the region of the heart or palpitations, while others present a wide variety of complaints, often with emotional overtones, which is more common in cases where NCA develops in patients with neuroses.

The most common complaint is pain in the region of the heart, which is characterized by cardialgia. They are more often stabbing, short-term (several seconds) with localization in the apex of the heart or aching, long-term (several hours) with localization in the precordial region. Irradiation of pain, as a rule, is absent, rarely pain is given under the left shoulder blade. Sometimes there is a combination of stabbing pains in the region of the apex of the heart and aching in the precordial region. The pains go away on their own or are stopped by taking sedatives (corvalol, valerian, valocordin). Intense pain in the region of the heart may be accompanied by a feeling of fear, shortness of breath, sweating.

Patients also complain of palpitations, interruptions in the work of the heart, dizziness, often loss of consciousness, more often when changing the position of the body from horizontal to vertical. The connection of these complaints with nervous and physical overstrain was noticed.

Some adolescents periodically experience an increase in blood pressure, which, as a rule, does not exceed 150/90 mm Hg. Art. or vice versa - its decrease below 100/60 mm Hg. Art. At the same time, in both cases, headaches, dizziness, flickering of “flies” before the eyes, and weakness appear. Both an increase and a decrease in blood pressure are often associated with nervous and physical overexertion.

Some adolescents complain of cold extremities, weakness, decreased physical performance, dyspeptic disorders (nausea, vomiting, heartburn, belching, etc.).

During an objective examination, there may be spots of hyperemia of irregular shape in the face, neck, anterior surface of the chest - enhanced mixed dermographism, especially pronounced in girls. The skin on the extremities has a marble appearance due to areas of cyanotic and pale color. There is sweating of the palms of the hands, armpits, limbs to the touch cold, wet.

The dimensions of the heart are not changed, sometimes an increased cardiac and apical beat is palpated. During auscultation of the heart, the tones are not changed, sometimes at an increased volume, splitting of the I and (or) II tone can be determined. A systolic murmur is often audible, usually soft, localized at the apex of the heart and along the left edge of the sternum. The cause of systolic murmur is in some cases a hyperkinetic type of hemodynamics with an acceleration of blood flow and the development of papillary muscle dysfunction, in others - myocardial dystrophy. In 10-15% of cases, a systolic murmur of a coarser sound is observed. Such noise is caused by prolapse or deflection of one or both leaflets of the mitral valve into systole, which is associated with mitral valve prolapse in connective tissue dysplasia of the heart (see connective tissue dysplasia of the heart).

During the day, pronounced lability of the pulse and blood pressure is detected. Of the rhythm disturbances, the most common are sinus arrhythmia, sinus bradycardia, sinus tachycardia, pacemaker migration and extrasystole. The appearance of these rhythm disturbances can also be associated with nervous and physical overexertion.

Pathological changes in other organs and systems are not detected during physical examination. Sometimes, on palpation of the abdomen, pain in the epigastric region is determined.

The course of the disease. With NCA, several types of clinical course of the disease can be distinguished. The first type proceeds mainly with a violation of cardiac activity (according to N. N. Savitsky - NCA according to the cardiac type). In this type, two clinical variants are observed: cardialgic and arrhythmic. In the first case, cardialgia is leading in the clinic, in the second - rhythm and conduction disturbances.

The second type proceeds with the clinic of vascular dystonia according to the hypertensive, hypotensive (Savitsky N. N., 1957) and regional (angiodystonic) type. The latter can occur in any part of the vascular system: arterial, venous and microcirculatory (Raynaud's syndrome, vertebrobasilar insufficiency, venous insufficiency, capillaropathy, etc.).

The third type is mixed, it includes any variants of the first two types in various combinations and is usually characterized by a severe course.

Among all types of clinical course, hypertensive and cardiac are the most common (respectively: 42 and 32%). Moreover, the hypertensive type is more often observed in young men, and the cardiac type in girls (Shcheglova L.V., 1993).

According to the severity of the course, NCA is divided into mild, moderate and severe.

A mild course is characterized by the fact that in the presence of complaints and symptoms of autonomic dysfunction, the ability to work does not suffer significantly, exercise tolerance is satisfactory. With a moderate course, patients present numerous complaints, cardialgia is expressed, combined with hypo- or hypertension, as well as rhythm and conduction disturbances, while exercise tolerance and working capacity are reduced. A severe course is accompanied by a multiplicity and persistence of manifestations of the disease, the appearance of complications, low tolerance to physical activity and disability.

Complications. Of the complications of NCA, myocardial dystrophy (34.5%) is in the first place, which indicates an organic lesion of the myocardium. Most often, myocardial dystrophy develops when NCA is combined with chronic foci of infection and high activity of the sympathetic division of the ANS (neurodystrophy). Of the other complications, sympathoadrenal and vagoinsular crises are much less common (respectively: 5.7 and 5.6%).

Sympathoadrenal crisis is characterized by the appearance of palpitations, trembling throughout the body, severe sweating, pain in the heart, increased breathing, increased blood pressure.

Vagoinsular crises occur with severe bradycardia, hypotension, with headache, severe weakness, dizziness, and sometimes fainting.

Other complications that occur in adolescents with NCA, especially of the cardiac type, include cardiac arrhythmias - extrasystole (20.8%), which occurs mainly in patients with myocardial dystrophy against the background of chronic focal infection.

The classification of NCA in adolescents is based on etiological, pathogenetic and clinical principles, as well as the severity of the course of the disease and the presence of complications.

By etiology:
primary:
constitutional and hereditary autonomic dysfunction;
pubertal-adolescent autonomic dysfunction;
neuroses.
secondary:
chronic focal infection;
diseases of the central and peripheral nervous system;
connective tissue dysplasia;
infections and intoxications;
physical and nervous strain;
others.
By pathogenesis:
with adaptation of vegetative provision;
with disadaptation of vegetative provision.
By clinic:
violation of cardiac activity (cardiac type):
cardialgic variant;
arrhythmic option.
violation of vascular tone:
hypertensive type;
hypotensive type;
regional type;
mixed.
Complications:
myocardial dystrophy;
sympathoadrenal crises;
vagoinsular crises;
rhythm and conduction disturbances.
According to the severity of the flow:
light;
average;
heavy.
Diagnostics. Indicators of clinical and biochemical blood tests do not go beyond normal values, which excludes heart damage of inflammatory origin.

In x-ray examination, the size of the heart and large vessels correspond to age, which is important in differential diagnosis with heart defects.

In an ECG study, changes are often absent, there may be signs of incomplete blockade of the right bundle branch block, which is a variant of the norm and is associated with a slowdown in excitation of the right supraventricular crest, which often occurs in adolescence. In 34.5% of cases, violations of the repolarization process are detected in the form of a decrease, smoothness and inversion of the T waves, indicating the development of myocardial dystrophy. These changes are unstable, and they disappear during pharmacological tests with vegetotropic drugs (obzidan and atropine) and potassium chloride. Obzidan should be used in cases where changes in the terminal part of the ventricular complex are combined with high activity and reactivity of the sympathetic division of the ANS, which is called the sympathicotonic (hyperkinetic) syndrome. The dose of obzidan is 40–60 mg, it is used sublingually with ECG registration before the test and 1 and 1.5 hours after taking the drug.

Atropine is used when there is a combination of a violation on the ECG of the repolarization process with high activity and reactivity of the parasympathetic division of the ANS. Atropine sulfate is administered intravenously in a 0.1% solution of 0.5–1.0 ml, ECG is recorded 30 minutes and 1 hour after administration.

Normalization of the repolarization process on the ECG during these tests indicates neurodystrophy due to autonomic dysfunction, and is an important sign in the differential diagnosis with myocarditis.

A potassium chloride test is more informative when NCA is combined with chronic focal infection, since these patients often develop potassium-deficient myocardial dystrophy. After the initial ECG recording, the patient is given 6 g of potassium chloride (drink with tomato juice) and the ECG is re-registered 1 and 1.5 hours after taking the drug. Normalization of the ECG indicates potassium-dependent myocardial dystrophy.

With bicycle ergometry, in 80% of cases, the ECG normalizes the repolarization process (Vecherinina K.O. et al., 1996).

Of the heart rhythm disorders in adolescents with NCA, the most common are sinus tachycardia (33.4%), pacemaker migration (29.1%), extrasystole (20.8%) and sinus bradycardia and bradyarrhythmia (16.7%) (Levina L.I., 1993). These rhythm disturbances depend on the nature of autonomic dysfunction. So, sinus tachycardia is most often observed in patients with high activity of the sympathetic department, the migration of the pacemaker - the parasympathetic department, and extrasystole - both departments of the ANS.

In 4.2% of cases, sinoatrial and atrioventricular (I degree) blockades are detected in patients with NCA. These blockades are observed against the background of sinus bradycardia or bradyarrhythmia and are due to the high activity of the parasympathetic division of the ANS with the development of vagal dysfunction of the sinus node and slowing of atrioventricular conduction. Vagal dysfunction of the sinus node may be accompanied by dizziness and fainting, especially with the development of vagoinsular crises.

To identify autonomic dysfunction, a simple and informative method is a rhythmographic study (cardiointervalography). This method allows you to evaluate the vegetative support of cardiac activity, which can proceed with adaptation and disadaptation (see Features of the cardiovascular system in the pubertal period, section rhythmographic study). In adolescents with NCA of primary genesis, disadaptation of the vegetative supply of cardiac activity occurs in 46% of cases, and of secondary genesis - in 63%, adaptive reactions are observed in 38 and 27% of cases, respectively, and only in 16 and 10% of cases, the vegetative supply is within the normal range (Shcheglova L. V., 2002).

In the severe course of the disease, the indicators of exercise tolerance during bicycle ergometry in most cases are low and correspond to low physical performance, especially in patients with disadaptation of the vegetative support of cardiac activity. In these patients, the reserve capacity of the myocardium is sharply reduced.

In the study of central hemodynamics in patients with NCA twice as often as in healthy people, hypo- and hyperkinetic types of hemodynamics are observed. In this case, the type of hemodynamics, as a rule, corresponds to the state of activity of the ANS departments. So, with high activity of the sympathetic division of the ANS, a hyperkinetic type of hemodynamics is observed (cardiac index - CI more than 4.0 l / (min m?), And with high activity of the parasympathetic division of the ANS - a hypokinetic type of hemodynamics - CI less than 3.0 l / (min m ?).

In an echocardiographic study (EchoCG), the thickness of the myocardium and the cavity of the heart is not changed, the contractile function is not impaired, with a hyperkinetic type of hemodynamics, the ejection fraction exceeds 70%. Echocardiography allows you to exclude valvular heart disease or other heart damage of an organic nature.

Diagnosis of peripheral vascular disorders is carried out using thermal imaging of the extremities and capillaroscopy. In thermal imaging of the upper and lower extremities, a decrease in infrared radiation in the distal parts of the hands and feet is determined, in severe cases up to thermal amputation, the thermal pattern is symmetrical, when conducting a test with nitroglycerin, a complete restoration of the thermal pattern is observed .

When examined by a psychologist, most patients with NCA of primary origin have a high level of anxiety, neuroticism and low stress resistance, which indicates a violation of socio-psychological adaptation.

In patients with NCA with dyspeptic disorders, fibrogastroscopy often shows pathological refluxes with symptoms of gastritis, duodenitis, esophagitis, the development of which is also due to autonomic dysfunction.

To resolve the issue of the primary or secondary genesis of NCA, it is necessary to consult with specialists:

Otorhinolaryngologist to identify foci of chronic infection;
psychologist and neuropathologist for diagnosing neurosis or diseases of the central and peripheral nervous system;
an ophthalmologist to study the vessels of the fundus in patients with hypo- and hypertension;
according to indications with other specialists (surgeon, endocrinologist, gynecologist, gastroenterologist, etc.).
Criteria for diagnosis. The main criteria for diagnosis are:
multiplicity and polymorphism of complaints mainly from the cardiovascular system;
asthenic syndrome, psycho-emotional disorders; violations of socio-psychological adaptation;
signs of autonomic dysfunction (clinical and according to rhythmographic studies);
violation of the process of repolarization on the ECG with its recovery when using pharmacological tests with vegetotropic drugs and potassium chloride;
decrease in tolerance to physical activity during a bicycle ergometric study;
detection of peripheral vascular disorders in thermal imaging;
favorable course without the development of cardiomegaly and heart failure.
Structure and examples of diagnosis. Clinical diagnosis is formed according to the classification. We give an example of the formulation of a clinical diagnosis.

The main diagnosis: NCA by cardiac type, disadaptation of the vegetative support of cardiac activity, the average severity of the course. Asthenoneurotic syndrome.

Complication: myocardial dystrophy, pacemaker migration.

differential diagnosis. In adolescents, NCA should be differentiated from many syndrome-like diseases, and first of all, nonspecific (infectious-allergic) myocarditis, rheumatism, and thyrotoxicosis.

Unlike NCA, in infectious-allergic myocarditis, the disease proceeds with an increase in the size of the heart and a decrease in its contractile function, and in severe cases, the development of heart failure. Of the rhythm disturbances, if with NCA there are mainly migration of the pacemaker and ventricular extrasystole, with myocarditis - extrasystole, both atrial and ventricular, often proceeding as an allorhythmia, as well as paroxysmal tachycardia. ECG repolarization disorders in myocarditis do not disappear during pharmacological tests, improvement in repolarization is observed during treatment, positive indicators of acute phase reactions (C-reactive protein, sialic acids, protein fractions, LDH, etc.) are noted.

With rheumatism, a systemic lesion of the connective tissue (heart, joints, skin, etc.) is determined, accompanied in the active phase by positive acute phase indicators and immunological disorders. In contrast to NCA, in rheumatism, a characteristic melody of a heart defect or a melody of its formation is heard. The diagnosis is specified by ultrasound.

A similar clinical picture is observed in adolescents with NCA and thyrotoxicosis. Therefore, in unclear cases, it is necessary to investigate the function of the thyroid gland. An increase in the thyroid gland and an increase in the level of thyroid hormones (triiodothyronine - T3 and thyroxine - T4) indicates thyrotoxicosis.

Disease outcomes. In primary NCA, adolescents are cured at the end of the puberty period, as well as successful treatment of neurosis and appropriate psychocorrection, elimination of bad habits, physical education, normalization of working and rest conditions, etc.

With secondary NCA, recovery of adolescents occurs with successful treatment of those diseases that contributed to the development of NCA (foci of chronic infection, diseases of the central and peripheral nervous system, etc.). Rarely, this disease continues into adulthood.

The prognosis for NCA is favorable, however, these patients, especially those with a severe course of the disease, should be classified as a “risk group”, since in the future, already in adulthood, they develop hypertension and coronary heart disease more often than in the general population (Belokon N A. et al., 1986; Lazarev V. I. et al., 1989; Kukharenko V. Yu. et al., 1990; Makolkin V. I., 1995; Kushakovsky M. S., 1996).

Treatment. Treatment of NCA is carried out taking into account the nature of autonomic dysfunction and its etiopathogenesis.

With NCA, which occurs against the background of neurosis, treatment with sedatives (preparations of valerian, bromine, etc.) is indicated, in more severe cases - tranquilizers (phenazepam, gidazepam).

Identification of violations of the socio-psychological adaptation of a teenager requires psychological correction by a psychotherapist. In the presence of foci of chronic infection, their mandatory sanitation (tonsillectomy, treatment of sinusitis, otitis media, dental caries).

If during the examination of a teenager other diseases and lesions are diagnosed (encephalopathy, deformity and osteochondrosis of the spine, deformity of the chest, menstrual irregularities, etc.), treatment of these diseases jointly with a therapist and an appropriate specialist is indicated. At the same time, it is necessary to carry out general strengthening treatment (vitamins, metabolics, adaptogens of plant origin: ginseng, eleutherococcus, Chinese magnolia vine, etc.).

Pathogenetic treatment is carried out using vegetotropic drugs.

With high activity and reactivity of the sympathetic division of the ANS, beta-blockers (anaprilin, propranolol, atenolol) are used in a daily dose not exceeding 50–60 mg.

With high activity and reactivity of the parasympathetic division of the ANS, anticholinergics (belloid, bellaspon, bellataminal) give a good effect.

Various physiotherapeutic influences and water procedures improve the function of the ANS (ultrasound and massage of the cervical-collar zone, circular shower, underwater massage, douche), balneotherapy (carbon dioxide, radon, oxygen, mineral baths), acupuncture, exercise therapy, hypoxic therapy.

Symptomatic treatment is aimed at leading clinical syndromes.

With a pronounced cardialgic syndrome, Corvalol, Valocordin should be used, and if there is no effect, calcium channel blockers (verapamil in a daily dose of 60–80 mg) should be used.

With the development of myocardial dystrophy, the appointment of metabolic drugs (riboxin, potassium preparations, B vitamins, mildronate, etc.)

Extrasystole does not require special treatment, since with effective treatment of NCA, it disappears on its own.

In diseases of the central and peripheral nervous system, as well as in the presence of regional cerebral dystonia, treatment should be prescribed by a neuropathologist after an appropriate neurological examination.

The duration of treatment depends on the severity of the course of the disease and is 1–2 months, however, after improvement in the condition, treatment should be continued with maintenance doses of selected drugs for several more months.

With mild and moderate severity of the course of the disease, it is advisable to carry out treatment on an outpatient basis or in a sanatorium-preventorium. In severe cases or the need for differential diagnosis with organic diseases of the cardiovascular system, examination and treatment in a hospital is indicated.

The criteria for the effectiveness of treatment are: improvement in the general condition, elimination of crises, disappearance of complaints, cardiac arrhythmias, normalization of the ECG and blood pressure, stabilization of hemodynamic parameters, etc.

Prevention consists in organizing the rational physical education of adolescents, giving up bad habits (smoking, drinking alcohol), eliminating physical and nervous overstrain, regulating the work and rest regime, good nutrition, preventing harmful occupational influences, and treating diseases that cause vegetative disorders.

Clinical examination of adolescents with NCA should be built individually (Medvedev V.P. et al., 1990). In moderate and severe NCA, adolescents should be observed in the 3rd dispensary group (D-3). At least 2 times a year, an examination is carried out by an adolescent therapist and a neuropathologist with a mandatory study of ECG, CIG and bicycle ergometry. A teenager can be removed from the dispensary after a year from the moment of improvement, disappearance of complaints, normalization of blood pressure and hemodynamics.

Expertise questions. Adolescents with NCA belong to the 3rd health group. The issue of admission to a particular medical group for physical education is decided taking into account the severity of the course of the disease, the functional state of the cardiovascular system and physical performance. Adolescents with a mild course of the disease and good physical performance are included in the main group. For the moderate severity of the course of the disease and satisfactory physical performance, a preparatory group is indicated, and for a severe course with low physical performance, a special group. Patients with a tendency to angiospasm, crises, fainting, combined with low and very low physical performance should be exempted from exams, especially during an exacerbation of the disease, and should not participate in labor associations of schoolchildren and student construction teams during the holidays.

For adolescents with NCA, work associated with physical and nervous overexertion, exposure to elevated ambient temperatures, the presence of toxic substances, noise and vibration, sharp fluctuations in barometric pressure, work at unprotected heights, near fires and water bodies should be considered contraindicated (Serdyukovskaya G. N., 1979).

When drafted into the army, patients with NCA should be examined twice in a hospital: the first time - after registration, again - before conscription. Depending on the severity of the course of the disease and in the presence of a complete clinical examination, the military medical commission decides on the degree of suitability or unfitness for military service.

In this part, we are talking about the features of the morphological development of the cardiovascular system: changes in blood circulation in a newborn; about the position, structure and size of the child's heart in the postnatal period; about age-related changes in heart rate and duration of the cardiac cycle; about age-related features of external manifestations of the activity of the heart. Features of the morphological development of the cardiovascular system.

Changes in blood circulation in a newborn. The act of giving birth to a child is characterized by its transition to completely different conditions of existence. Changes occurring in the cardiovascular system are primarily associated with the inclusion of pulmonary respiration. At the time of birth, the umbilical cord (umbilical cord) is bandaged and cut, which stops the exchange of gases in the placenta. At the same time, the content of carbon dioxide in the blood of the newborn increases and the amount of oxygen decreases. This blood, with a changed gas composition, comes to the respiratory center and excites it - the first breath occurs, during which the lungs expand and the vessels in them expand. Air enters the lungs for the first time. The dilated, almost empty vessels of the lungs have a large capacity and low blood pressure. Therefore, all the blood from the right ventricle through the pulmonary artery rushes to the lungs. The botallian duct gradually overgrows. Due to the changed blood pressure, the oval window in the heart is closed by a fold of the endocardium, which gradually grows, and a continuous septum is created between the atria. From this moment, the large and small circles of blood circulation are separated, only venous blood circulates in the right half of the heart, and only arterial blood circulates in the left half. At the same time, the vessels of the umbilical cord cease to function, they overgrow, turn into ligaments. So at the time of birth, the fetal circulatory system acquires all the features of its structure in an adult.

The position, structure and size of the child's heart in the postnatal period. The heart of a newborn differs from that of an adult in shape, relative mass, and location. It has an almost spherical shape, its width is somewhat greater than its length. The walls of the right and left ventricles are the same in thickness. In a newborn, the heart is very high due to the high position of the diaphragm. By the end of the first year of life, due to the lowering of the diaphragm and the transition of the child to a vertical position (the child is sitting, standing), the heart takes an oblique position. By the age of 2-3, its apex reaches the 5th left rib, by 5 years it shifts to the fifth left intercostal space. In 10-year-old children, the boundaries of the heart are almost the same as in adults. Since the separation of the large and small circles of blood circulation, the left ventricle performs much more work than the right, since the resistance in the large circle is greater than in the small one. In this regard, the muscle of the left ventricle develops intensively, and by six months of life the ratio of the wall of the right and left ventricles becomes the same as in an adult - 1: 2.11 (in a newborn it is 1: 1.33). The atria are more developed than the ventricles. The weight of the heart of a newborn is on average 23.6 g (fluctuations are possible from 11.4 to 49.5 g) and is 0.89% of body weight (in an adult, this percentage ranges from 0.48 to 0.52%). With age, the mass of the heart increases, especially the mass of the left ventricle. During the first two years of life, the heart grows rapidly, and the right ventricle is somewhat behind in growth from the left one. By 8 months of life, the mass of the heart doubles, by 2-3 years - 3 times, by 5 years - 4 times, by 6 11 times. From 7 to 12 years of age, the growth of the heart slows down and somewhat lags behind the growth of the body. At the age of 14-15 - during puberty - an increased growth of the heart occurs again. Boys have a larger heart than girls. But at the age of 11, girls begin a period of increased heart growth (for boys, it begins at 12 years old), and by the age of 13-14, its mass becomes larger than that of boys. By the age of 16, the heart in boys becomes heavier again than in girls.

Age-related changes in heart rate and duration of the cardiac cycle. In the fetus, the heart rate ranges from 130 to 150 beats per minute. At different times of the day, it can differ in the same fetus by 30-40 contractions. At the moment of fetal movement, it increases by 13-14 beats per minute. With a short-term holding of breath in the mother, the heart rate of the fetus increases by 8-11 beats per minute. The muscular work of the mother does not affect the heart rate of the fetus. In a newborn, the heart rate is close to its value in the fetus and is 120-140 beats per minute. Only during the first few days there is a temporary slowdown in heart rate to 80-70 beats per minute. A high heart rate in newborns is associated with an intensive metabolism and the absence of influences from the vagus nerves. But if in the fetus the heart rate is relatively constant, then in the newborn it easily changes under the influence of various stimuli acting on the receptors of the skin, organs of vision and hearing, olfactory, gustatory and receptors of internal organs. With age, the heart rate decreases, and in adolescents, it approaches the value of adults. Changes in heart rate in children with age. Age Heart rate Age Heart rate

Newborn 120-140 8 years 80-85

6 months 130-135 9 years 80-85

1 year 120-125 10 years 78-85

2 years 110-115 11 years 78-84

3 years old 105-110 12 years old 75-82

4 years old 100-105 13 years old 72-80

5 years old 98-100 14 years old 72-80

6 years 90-95 15 years 70-76

The decrease in the number of heartbeats with age is associated with the influence of the vagus nerve on the heart. Gender differences in heart rate were noted: in boys it is less frequent than in girls of the same age. A characteristic feature of the activity of the child's heart is the presence of respiratory arrhythmia: at the moment of inhalation, the heart rate increases, and during exhalation it slows down. In early childhood, arrhythmia is rare and mild. Starting from preschool age and up to 14 years, it is significant. At the age of 15-16 years, there are only isolated cases of respiratory arrhythmia. In children, the heart rate undergoes large changes under the influence of various factors. Emotional influences lead, as a rule, to an increase in the rhythm of cardiac activity. It increases significantly with an increase in the temperature of the external environment and during physical work, and decreases with a decrease in temperature. The heart rate during physical work increases to 180-200 beats per minute. This is due to the insufficient development of mechanisms that provide an increase in oxygen consumption during operation. In older children, more advanced regulatory mechanisms ensure a rapid restructuring of the cardiovascular system in accordance with physical activity. Due to the high heart rate in children, the duration of the entire cycle of contractions is much shorter than in adults. If in an adult it leaves 0.8 seconds, then in the fetus - 0.46 seconds, in a newborn child - 0.4-0.5 seconds, in 6-7-year-old children the duration of the cardiac cycle is 0.63 seconds, in children 12 years of age - 0.75 sec, i.e. its value is almost the same as in adults. In accordance with the change in the duration of the cycle of heart contractions, the duration of its individual phases also changes. By the end of pregnancy in the fetus, the duration of ventricular systole is 0.3-0.5 seconds, and diastole - 0.15-0.24 seconds. The phase of ventricular tension in a newborn lasts - 0.068 seconds, and in infants - 0.063 seconds. The ejection phase in newborns is carried out in 0.188 seconds, and in infants - in 0.206 seconds. Changes in the duration of the cardiac cycle and its phases in other age groups are shown in the table. The duration of individual phases of the cardiac cycle (in seconds) in children of different age groups (according to B.L. Komarov) Phases of the cardiac cycle Age groups

8-11 years old 12-15 years old 20-60 years old

Ventricular systole 0.275 0.281 0.301

Atrial systole 0.089 0.090 0.078

Ventricular diastole 0.495 0.545 0.579

Cycle duration 0.771 0.826 0.880 With intense muscle load, the phases of the cardiac cycle are shortened. The duration of the tension phase and the exile phase at the beginning of work is especially sharply reduced. After some time, their duration slightly increases and becomes stable until the end of the work.

Age-related features of the external manifestations of the activity of the heart. The cardiac impulse is clearly visible to the eye in children and adolescents with poorly developed subcutaneous adipose tissue, and in children with good fatness, the cardiac impulse is easily determined by palpation. In newborns and children under 2-3 years of age, cardiac the push is felt in the 4th left intercostal space 1-2 cm outside the nipple line, in children 3-7 years of age and subsequent age groups it is determined in the 5th intercostal space, somewhat varying outside and inside from the nipple line. children are somewhat shorter than adults. If in adults the first tone lasts 0.1-0.17 seconds, then in children it is 0.1-0.12 seconds. The second tone in children is longer than in adults. In children, it lasts 0.07-0.1 seconds, and in adults - 0.06-0.08 seconds. Sometimes in children from 1 to 3 years old, there is a splitting of the second tone, associated with a slightly different closure of the semilunar valves of the aorta and pulmonary artery, and a splitting of the first tone, which is due to asynchronous closure of the mitral and tricuspid valves. Often, a third tone is recorded in children, very quiet, deaf and low. It occurs at the beginning of diastole 0.1-0.2 sec after the second tone and is associated with rapid stretching of the ventricular muscle that occurs when blood enters them. In adults, the third tone lasts 0.04-0.09 seconds, in children 0.03-0.06 seconds. In newborns and infants, the third tone is not audible. During muscular work, positive and negative emotions, the strength of heart tones increases, during sleep it decreases. heart, its position, regulation, etc. In the fetus, an electrocardiogram is recorded at the 15-17th week of pregnancy. The time for conducting excitation from the atria to the ventricles (PQ interval) in the fetus is shorter than in the newborn. In newborns and children of the first three months of life, this time is 0.09-0.12 seconds, and in older children it is 0.13-0.14 seconds. The QRS complex in newborns is shorter than at an older age. Separate teeth of the electrocardiogram in children of this age are different in different leads. In infants, the P wave remains strongly pronounced in the electrocardiogram, which is explained by the larger size of the atria. The QRS complex is often multiphase, the R wave predominates in it. Changes in the QRS complex are associated with uneven growth of the conduction system of the heart. At preschool age, the electrocardiogram of most children of this age is characterized by a slight decrease in the P and Q waves. The R wave increases in all leads, which is associated with the development of the left ventricular myocardium. At this age, the duration of the QRS complex and the P-Q interval increase, which depends on the fixation of the influences of the vagus nerve on the heart. In school-age children, the duration of the cardiac cycle (R-R) increases even more and averages 0.6-0.85 sec. The value of the R wave in the first lead in adolescents approaches its value in an adult. The Q wave decreases with age, and in adolescents also approaches its size in an adult. 7.4. Heart: structure and age-related changes The heart is a hollow muscular organ divided into four chambers: two atria and two ventricles. The left and right sides of the heart are separated by a solid septum. Blood from the atria enters the ventricles through openings in the septum between the atria and ventricles. The holes are equipped with valves that open only towards the ventricles. Valves are formed by interlocking flaps and therefore are called flap valves. The valve is bicuspid on the left side of the heart, and tricuspid on the right. Semilunar valves are located at the exit point of the aorta from the left ventricle and the pulmonary artery from the right ventricle. The semilunar valves pass blood from the ventricles to the aorta and pulmonary artery and prevent the reverse movement of blood from the vessels to the ventricles. Heart valves ensure the movement of blood in only one direction: from the atria to the ventricles and from the ventricles to the arteries. The mass of the human heart is from 250 to 360

The expanded upper part of the heart is called the base, the narrowed lower part is called the apex. The heart lies obliquely behind the sternum. Its base is directed back, up and to the right, and the top is directed down, forward and to the left. The apex of the heart is adjacent to the anterior chest wall in the area near the left intercostal space; here, at the moment of contraction of the ventricles, a cardiac impulse is felt. The main mass of the wall of the heart is a powerful muscle - the myocardium, consisting of a special kind of striated muscle tissue. The thickness of the myocardium is different in different parts of the heart. It is thinnest in the atria (2–3 mm). The left ventricle has the most powerful muscular wall: it is 2.5 times thicker than in the right ventricle. Typical and atypical muscles of the heart. The bulk of the heart muscle is represented by fibers typical of the heart, which provide contraction of the heart. Their main function is contractility. This is a typical, working muscle of the heart. In addition to it, there are atypical fibers in the heart muscle, the activity of which is associated with the occurrence of excitation in the heart and the conduction of excitation from the atria to the ventricles. Atypical muscle fibers differ from contractile fibers both in structure and in physiological properties. They have a less pronounced transverse striation, but they have the ability to be easily excited and more resistant to harmful influences. For the ability of the fibers of atypical muscles to conduct the resulting excitation through the heart, it is called the conduction system of the heart. Atypical muscles occupy a very small part of the heart in terms of volume. The accumulation of atypical muscle cells is called nodes. One of these nodes is located in the right atrium, near the confluence (sinus) of the superior vena cava. This is the sinoatrial node. Here, in the heart of a healthy person, excitation impulses arise that determine the rhythm of heart contractions. The second node is located on the border between the right atrium and the ventricles in the septum of the heart, it is called the atrioventricular, or atrioventricular, node. In this region of the heart, excitation spreads from the atria to the ventricles. From the atrioventricular node, excitation is directed along the atrioventricular bundle (Hiss bundle) of the fibers of the conduction system, which is located in the septum between the ventricles. The trunk of the atrioventricular bundle is divided into two legs, one of them goes to the right ventricle, the other to the left. Excitation from the atypical muscles is transmitted to the fibers of the contractile muscles of the heart using fibers related to the atypical muscles. Age-related changes in the heart. The heart of a child after birth not only grows, but processes of shaping take place in it (shape, proportions change). The heart of a newborn occupies a transverse position and has an almost spherical shape. The relatively large liver makes the arch of the diaphragm high, so the position of the heart in the newborn is higher (it is at the level of the fourth left intercostal space). By the end of the first year of life, under the influence of sitting and standing and in connection with the lowering of the diaphragm, the heart takes an oblique position. By 2-3 years, the apex of the heart reaches the fifth rib. In ten-year-old children, the boundaries of the heart become almost the same as in adults. During the first year of life, the growth of the atria outstrips the growth of the ventricles, then they grow almost the same, and after 10 years, the growth of the ventricles begins to overtake the growth of the atria. The heart in children is relatively larger than in adults. Its mass is approximately 0.63-0.80% of body weight, in an adult - 0.48-0.52%. The heart grows most intensively in the first year of life: by 8 months, the mass of the heart doubles, triples by 3 years, quadruples by 5 years, and 11 times by 16 years. The heart mass in boys in the first years of life is greater than girls. At the age of 12–13, a period of increased heart growth begins in girls, and its mass becomes larger than that of boys. By the age of 16, the heart of girls again begins to lag behind the heart of boys in mass. Cardiac cycle. The heart contracts rhythmically: contractions of the heart (systole) alternate with their relaxation (diastole). The period of one contraction and one relaxation of the heart is called the cardiac cycle. In a state of relative rest, the adult heart beats about 75 times per minute. This means that the entire cycle lasts about 0.8 s. Each cardiac cycle consists of three phases: 1) atrial systole (lasts 0.1 s); 2) ventricular systole (lasts 0.3 s); 3) general pause ( 0.4 s). With great physical exertion, the heart contracts more often than 75 times per minute, while the duration of the total pause decreases.

During the development of a child, significant morphological and functional changes occur in his cardiovascular system. The formation of the heart in the embryo begins from the second week of embryogenesis and a four-chambered heart is formed by the end of the third week. The blood circulation of the fetus has its own characteristics, primarily related to the fact that before birth, oxygen enters the body through the placenta and the so-called umbilical vein.

The umbilical vein branches into two vessels, one feeding the liver, the other connected to the inferior vena cava. As a result, oxygen-rich blood (from the umbilical vein) and blood flowing from the organs and tissues of the fetus mix in the inferior vena cava. Thus, mixed blood enters the right atrium. As after birth, the atrial systole of the fetal heart directs blood into the ventricles, from there it enters the aorta from the left ventricle, and from the right ventricle into the pulmonary artery. However, the fetal atria are not isolated, but are connected using an oval hole, so the left ventricle sends blood to the aorta partially from the right atrium. A very small amount of blood enters the lungs through the pulmonary artery, since the lungs in the fetus do not function. Most of the blood ejected from the right ventricle into the pulmonary trunk, through a temporarily functioning vessel - the ductus botulinum - enters the aorta.

The most important role in the blood supply to the fetus is played by the umbilical arteries, which branch off from the iliac arteries. Through the umbilical opening, they leave the body of the fetus and, branching, form a dense network of capillaries in the placenta, from which the umbilical vein originates. The fetal circulatory system is closed. The mother's blood never enters the fetal blood vessels and vice versa. The supply of oxygen to the blood of the fetus is carried out by diffusion, since its partial pressure in the maternal vessels of the placenta is always higher than in the blood of the fetus.

After birth, the umbilical arteries and vein become empty and become ligaments. With the first breath of a newborn, the pulmonary circulation begins to function. Therefore, usually the botallian duct and the foramen ovale quickly overgrow. In children, the relative mass of the heart and the total lumen of the vessels are greater than in adults, which greatly facilitates the processes of blood circulation. The growth of the heart is closely related to the overall growth of the body. The heart grows most intensively in the first years of life and at the end of adolescence. The position and shape of the heart also change with age. In a newborn, the heart is spherical in shape and is located much higher than in an adult. Differences in these indicators are eliminated only by the age of ten. By the age of 12, the main functional differences in the cardiovascular system also disappear.

The heart rate (Table 5) in children under 12 - 14 years of age is higher than in adults, which is associated with the predominance of the tone of sympathetic centers in children.

In the process of postnatal development, the tonic influence of the vagus nerve is constantly increasing, and in adolescence, the degree of its influence in most children approaches the level of adults. A delay in the maturation of the tonic influence of the vagus nerve on cardiac activity could indicate a retardation of the child's development.

Table 5

Resting heart rate and respiration rate in children of different ages.

Table 6

The value of blood pressure at rest in children of different ages.

Blood pressure in children is lower than in adults (Table 6), and the rate of circulation is higher. The stroke volume of blood in a newborn is only 2.5 cm3, in the first year after birth it increases four times, then the growth rate decreases. To the level of an adult (70 - 75 cm3), stroke volume approaches only 15 - 16 years. With age, the minute volume of blood also increases, which provides the heart with increasing opportunities for adaptation to physical exertion.

Bioelectrical processes in the heart also have age-related features, so the electrocardiogram approaches the form of an adult by the age of 13-16.

Sometimes in the pubertal period there are reversible disturbances in the activity of the cardiovascular system associated with the restructuring of the endocrine system. At the age of 13-16, there may be an increase in heart rate, shortness of breath, vasospasm, violations of the electrocardiogram, etc. In the presence of circulatory dysfunctions, it is necessary to strictly dose and prevent excessive physical and emotional stress in a teenager.