Transcranial doppler ultrasound. Treatment and symptoms of vertebral artery syndrome

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The study of the specifics and patterns of organ circulation, begun in the 50s of the XX century, is associated with two main points - the development of methods that make it possible to quantify blood flow and resistance in the vessels of the organ under study, and a change in ideas about the role of the nerve factor in the regulation vascular tone. Under the tone of any organ, tissue or cell is understood the state of long-term excitation, expressed by activity specific to this formation, without the development of fatigue.

Due to the traditionally established direction of research on the nervous regulation of blood circulation for a long time it was believed that vascular tone is normally created due to the constrictor influences of the sympathetic vasoconstrictor nerves. This neurogenic theory of vascular tone made it possible to consider all changes in the organ circulation as a reflection of the innervation relationships that govern blood circulation as a whole. At present, with the possibility of obtaining a quantitative characteristic of organ vasomotor reactions, there is no doubt that vascular tone is basically created by peripheral mechanisms, and nerve impulses correct it, ensuring the redistribution of blood between different vascular areas.

Regional and organ circulation

Regional circulation- a term adopted to characterize the movement of blood in organs and organ systems belonging to one area of ​​​​the body (region). In principle, the terms "organ circulation" and "regional circulation" do not correspond to the essence of the concept, since there is only one heart in the system, and this, discovered by Harvey, blood circulation in a closed system is blood circulation, i.e. circulation of blood during its movement. At the level of an organ or region, parameters such as blood supply can be determined; pressure in the artery, capillary, venule; resistance to blood flow in various parts of the organ vascular bed; volumetric blood flow; the volume of blood in the organ, etc. It is these parameters that characterize the movement of blood through the vessels of the organ that are implied when using term "organ circulation «.

The speed of blood flow in the vessels

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As follows from the Poiseuille formula, the blood flow velocity in the vessels is determined (in addition to nervous and humoral influences) by the ratio of five local factors:

pressure gradient, which depends on: 1) Blood pressure,2) Venous pressure

vascular resistance, which depends on: 3) The radius of the vessel,4) The length of the vessel,5) Blood viscosity.

1) Increased blood pressure leads to an increase in the pressure gradient and, consequently, to an increase in blood flow in the vessels. A decrease in blood pressure causes changes in blood flow that are opposite in sign.

2) Increased venous pressure leads to a decrease in the pressure gradient, resulting in a decrease in blood flow. As venous pressure decreases, the pressure gradient will increase, which will increase blood flow.

3) Changes in the radius of vessels can be active or passive. Any changes in the radius of the vessel that do not occur as a result of changes in the contractile activity of their smooth muscles are passive.

The latter may be due to both intravascular and extravascular factors.

Intravascular factor, causing passive changes in the lumen of the vessel in the body is intravascular pressure. An increase in blood pressure causes a passive expansion of the lumen of the vessels, which can even neutralize the active constrictor reaction of arterioles in case of their low severity. Similar passive reactions can occur in the veins when the venous pressure changes.

Extravascular factors, capable of causing passive changes in the lumen of the vessels, not inherent in all vascular areas and depend on the specific function of the organ.

Thus, the vessels of the heart can passively change their lumen as a result of :

a) changes in heart rate,
b) The degree of tension of the heart muscle during its contractions,
c) Changes in intraventricular pressure.

Bronchomotor reactions affect the lumen of the pulmonary vessels. The motor or tonic activity of the sections of the gastrointestinal tract or skeletal muscles will change the lumen of the vessels of these areas. Therefore, the degree of compression of vessels by extravascular elements can determine the size of their lumen.

4) Vessel length

5) Blood viscosity

Active vascular responses

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Active vascular responses are those that result from contraction of the smooth muscles of the vessel wall. This mechanism is characteristic mainly of arterioles, although macro- and microscopic muscle vessels are also able to influence blood flow by actively constricting or dilating.

There are many stimuli that cause active changes in the lumen of the vessels. These include, first of all,

1) Physical,

2) Nervous,

3) Chemical influences.

3.1. Physical factors affecting the lumen of blood vessels

a) Intravascular pressure, changes in which affect the degree of tension (contraction) of vascular smooth muscles. Thus, an increase in intravascular pressure entails an increase in the contraction of vascular smooth muscles, and, conversely, its decrease causes a decrease in the tension of the vascular muscles (the Ostroumov-Bayliss effect). This mechanism provides, at least in part, autoregulation of blood flow in the vessels.

b) Temperature. To increase the temperature of the blood vessels internal organs respond with expansion, but with an increase in temperature environment- narrowing, although the vessels of the skin dilate at the same time.

c) Vessel length in most regions is relatively constant, which is why relatively little attention is paid to this factor. However, in organs that perform periodic or rhythmic activity (lungs, heart, gastrointestinal tract), vessel length may play a role in changes in vascular resistance and blood flow. So, for example, an increase in lung volume (on inspiration) causes an increase in the resistance of the pulmonary vessels, both as a result of their narrowing and elongation. Therefore, changes in vessel length may contribute to respiratory variations in pulmonary blood flow.

d) Blood viscosity also affects blood flow in the vessels. At high rate hematocrit resistance to blood flow can be significant.

3.2. Autoregulation of blood flow

Under the autoregulation of blood flow is understood the tendency to maintain its value in organ vessels. It should not, of course, be understood that with significant fluctuations in blood pressure (from 70 to 200 mm Hg), organ blood flow remains constant. The point is that these shifts in blood pressure cause smaller changes in blood flow than they could be in a passive elastic tube.

Autoregulation of blood flow is highly effective in the vessels of the kidneys and brain (pressure changes in these vessels almost do not cause shifts in blood flow), somewhat less - in the vessels of the intestine, moderately effective - in the myocardium, relatively ineffective - in the vessels of the skeletal muscles and very weakly effective - in the lungs ( table 7.4). The regulation of this effect is carried out by local mechanisms as a result of changes in the lumen of the vessels, and not the viscosity of the blood.

Table 7.4 Regional features of blood flow autoregulation and post-occlusive (reactive) hyperemia.
Region	Autoregulation (stabilization) of blood flow during changes in blood pressure	Reactive hyperemia
		threshold duration of occlusion	maximum increase in blood flow	main factor
Brain	Well expressed, D, -80+160	3 - 5 s	1.5 — 2	Stretch response mechanism.
Myocardium	Well expressed, 4-75+140	2 - 20 s	2 — 3	Adenosine, potassium ions, etc.
Skeletal muscles	Expressed with a high initial vascular tone, D=50+100	1 - 2 s	1.5 — 4	Stretch response mechanism, metabolic factors, lack of O 2 .
Intestines	On the general blood flow is not so clearly expressed. In the mucosa it is more fully expressed, D=40+125	30 - 120 s	1.5 — 2	Metabolites
Liver	Not found	not studied	Weakly expressed. Hyperemia is the second phase of the reaction to arterial occlusion.	local hormones
Leather		0.5-6 min	1.5 — 4	Prostaglandins
Note: Ds is the range of blood pressure values ​​(mm Hg), in which the blood flow stabilizes.

3.3. Theories explaining the mechanism of blood flow autoregulation

There are several theories explaining the mechanism of blood flow autoregulation:

A)myogenic, recognizing as a basis the transmission of excitation through smooth muscle cells;
b)neurogenic, involving interaction between smooth muscle cells and receptors in vascular wall sensitive to changes in intravascular pressure;
V)tissue pressure theory, based on data on shifts in the capillary filtration of a liquid with a change in pressure in the vessel;
G)exchange theory, suggesting the dependence of the degree of contraction of vascular smooth muscles on metabolic processes (vasoactive substances released into the bloodstream during metabolism).

Close to the effect of blood flow autoregulation isveno-arterial effect, which manifests itself in the form of an active reaction of the arteriolar vessels of the organ in response to pressure changes in its venous vessels. This effect is also carried out by local mechanisms and is most pronounced in the vessels of the intestines and kidneys.

Basal tone

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Vessels devoid of nervous and humoral influences, as it turned out, retain (although V at least) the ability to resist blood flow. Denervation of skeletal muscle vessels, for example, approximately doubles the blood flow in them, but the subsequent introduction of acetylcholine into the blood flow of this vascular area can cause a further tenfold increase in blood flow in it, indicating that the ability of the vessels to vasodilate remains in this case. To designate this feature of denervated vessels to resist blood flow, the concept of "basal" vascular tone has been introduced.
Basal vascular tone is determined by structural and myogenic factors. Its structural part is created by a rigid vascular “bag” formed by collagen fibers, which determines the resistance of blood vessels if the activity of their smooth muscles is completely excluded. The myogenic part of the basal tone is provided by the tension of vascular smooth muscles in response to the tensile force of arterial pressure. Consequently, changes in vascular resistance under the influence of nerve or humoral factors superimposed on the basal tone, which is more or less constant for a certain vascular area. If there are no nervous and humoral influences, and the neurogenic component of vascular resistance is zero, the resistance to their blood flow is determined by the basal tone.

Since one of the biophysical features of the vessels is their ability to stretch, then with an active constrictor reaction of the vessels, changes in their lumen depend on oppositely directed influences:

1) Contracting smooth mouse vessels that reduce their lumen, and

2) High blood pressure in the vessels, which stretches them.

The extensibility of the vessels of various organs differs significantly. With an increase in blood pressure by only 10 mm Hg. (from 110 to 120 mm Hg), the blood flow in the intestinal vessels increases by 5 ml / min, and in the myocardial vessels 8 times more - by 40 ml / min.

Differences in their initial lumen may also affect the magnitude of vessel reactions..
Attention is drawn to the ratio of the thickness of the vessel wall to its lumen. It is believed that what. the above mentioned ratio (wall/clearance), i.e. the more wall mass is inside the “line of force” of smooth muscle shortening, the more pronounced the narrowing of the lumen of the vessels. In this case, with the same amount of contraction of smooth muscles in arterial and venous vessels, the decrease in lumen will always be more pronounced in arterial vessels, since the structural "possibilities" of reducing the lumen are more inherent in vessels with a high wall/lumen ratio.

On this basis, one of the theories of development is built. hypertension in a person.
Changes in transmural pressure (the difference between intra- and extravascular pressure) affect the lumen of blood vessels and, consequently, their resistance to blood flow and blood content in them, which especially affects the venous region, where the extensibility of the vessels is high and significant changes in the volume of blood contained in them can take place at small pressure shifts. Therefore, changes in the lumen of the venous vessels will cause corresponding changes in transmural pressure, which can lead to passive-elastic return of blood from this area.
Consequently, the ejection of blood from the veins, which occurs with increased impulses in the vasomotor nerves, can be due to both active contraction of the smooth muscle cells of the venous vessels and their passive elastic recoil. Relative value passive ejection of blood in this situation will depend on the initial pressure in the veins. If the initial pressure in them is low, its further decrease can cause collapse of the veins, leading to a very pronounced passive ejection of blood. Neurogenic constriction of the veins in this situation will not cause any significant ejection of blood from them, and as a result, an erroneous conclusion can be made that the nervous regulation of this section is insignificant. On the contrary, if the initial transmural pressure in the veins is high, then a decrease in this pressure will not lead to collapse of the veins and their passive-elastic recoil will be minimal. In this case, active constriction of the veins will cause a significantly greater ejection of blood and show true value neurogenic regulation of venous vessels.

It has been proven that the passive component of blood mobilization from veins at low pressure in them is very pronounced., but becomes very small at a pressure of 5-10 mm Hg. In this case, the veins have a circular shape and the ejection of blood from them under neurogenic influences is due to the active reactions of these vessels. However, when the venous pressure rises above 20 mm Hg. the value of the active ejection of blood decreases again, which is a consequence of the "overstrain" of the smooth muscle elements of the venous walls.
However, it should be noted that the pressure values ​​at which active or passive ejection of blood from the veins predominates were obtained in studies on animals (cats), in which the hydrostatic load of the venous section (due to the position of the body and size of the animal) rarely exceeds 10-15 mmHg. Humans seem to have other features, since most of their veins are located along the vertical axis of the body and are therefore subject to a higher hydrostatic load.
During a person's quiet standing, the volume of veins located below the level of the heart increases by about 500 ml, and even more if the leg veins are dilated. This is what can be the cause of dizziness or even fainting with prolonged standing, especially in cases where, with high temperature environment, vasodilatation of the skin takes place. Insufficiency of venous return in this case is not due to the fact that “the blood must rise up”, but to increased transmural pressure and the resulting stretching of the veins, as well as stagnation of blood in them. Hydrostatic pressure in the veins of the dorsum of the foot in this case can reach 80-100 mm Hg.
However, already the first step creates an external pressure of the skeletal muscles on their veins, and the blood rushes to the heart, as the valves of the veins prevent reverse current blood. This leads to emptying of the veins and skeletal muscles of the limbs and a decrease in venous pressure in them, which returns to its original level at a rate depending on the blood flow in this limb. As a result of a single muscle contraction, almost 100% of venous blood is expelled. calf muscle and only 20% of the blood of the thigh, and with rhythmic exercises, the emptying of the veins of this muscle occurs by 65%, and the thigh - by 15%.
Stretching of the veins of the organs abdominal cavity in the standing position is minimized as a result of the fact that when moving to vertical position pressure inside the abdominal cavity rises.

Among the main phenomena inherent in organ circulation, in addition to autoregulation of blood flow, the dependence of vascular reactions on their initial tone, on the strength of the stimulus, are functional (working) hyperemia, as well as reactive (post-occlusive) hyperemia. These phenomena are characteristic of regional blood circulation in all areas.

Working (or functional) hyperemia - an increase in organ blood flow, accompanying an increase in the functional activity of the organ. An increase in blood flow and blood filling in the contracting skeletal muscle is shown; salivation is also accompanied by a sharp increase in blood flow through dilated vessels salivary gland. Known hyperemia of the pancreas at the time of digestion, as well as the intestinal wall during the period of increased motility and secretion. An increase in myocardial contractile activity leads to an increase in coronary blood flow, activation of brain areas is accompanied by an increase in their blood supply, increased blood supply to the kidney tissue is recorded with an increase in natriuresis.

Reactive (or post-occlusive) hyperemia - an increase in blood flow in the vessels of the body after a temporary cessation of blood flow. It manifests itself in isolated skeletal muscles and in the limbs of humans and animals, is well expressed in the kidney and brain, and takes place in the skin and intestines.
A relationship has been established between changes in blood flow in the organ and chemical composition environment surrounding intraorganic vessels. The expression of this connection is local vasodilatory reactions in response to the artificial introduction into the vessels of tissue metabolism products (CO2, lactate) and substances, changes in the concentration of which in the intercellular environment are accompanied by shifts in cell function (ions, adenosine, etc.). The organ specificity of these reactions was noted: a special activity of CO2, K ions in the cerebral vessels, adenosine - in the coronary ones.
There are known qualitative and quantitative differences in the vascular reactions of organs to stimuli of different strengths.

Autoregulatory response to a decrease in pressure, in principle, resembles a "reactive" hyperemia caused by temporary occlusion of the artery. In accordance with this, the data in Table 7.4 indicate that the shortest threshold arterial occlusions are recorded in the same regions where autoregulation is effective. The post-occlusion increase in blood flow is significantly weaker (in the liver) or requires longer ischemia (in the skin), i.e. is weaker where autoregulation is not found.

Functional hyperemia organs is a strong proof of the main postulate of the physiology of blood circulation, according to which the regulation of blood circulation is necessary for the implementation of the nutritional function of blood flow through the vessels. Table 7.5 summarizes the basic concepts of functional hyperemia and shows that the increased activity of almost every organ is accompanied by an increase in blood flow through its vessels.

Table 7.5 Regional features of functional hyperemia
Organ	Functional activity gain indicator	Change in blood flow	The main factor (factors) of the mechanism
Brain	Local neuronal activation of brain zones.	Local increase by 20-60%.	The initial "fast" factor (nervous or chemical: potassium, adenosine, etc.).
	General activation of the cortex.	In the cortex, an increase of 1.5-2 times.	Subsequent "slow" factor (РСО 2 , pH, etc.).
	Seizures.	In the cortex, an increase of 2-3 times.
Myocardium	Increase in the frequency and force of contractions of the heart.	Magnification up to 6x.	Adenosine, hyperosmia, potassium ions, etc. Histomechanical effects.
Skeletal muscles	Contractions of muscle fibers.	Zoom up to 10x in two modes.	Ions of potassium, hydrogen. Histomechanical influences.
Intestines	Increased secretion, motility and absorption.	Increase up to 2-4 times.	RO 2, metabolites, ingestive hormones, serotonin, local reflex.
Pancreas	Increased exo-secretion.	Increase.	Metabolites, intestinal hormones, kinins.
Salivary glands	Increased salivation.	Magnification up to 5x.	Influence of impulses of parasympathetic fibers, kinins, hysumechanical influences.
Liver	Strengthening of exchange reactions.	Local zoom (?).	Little explored.
Bud	Increased sodium reabsorption.	Zoom up to 2x.	Bradykinin, hyperosmia.
Spleen	Stimulation of erythropoiesis.	Increase.	Adenosine
Bone	Rhythmic deformation of the bone.	Increase to 2- multiple.	mechanical influences.
Fat	Neurogenic enhancement of lipolysis through cyclic AMP.	Increase.	Adenosine, adrenergic influences.
Leather	Temperature increase, UV irradiation, mechanical stimulation.	Magnification up to 5x.	Decreased constriction impulses, metabolites, active substances from degranulated mast cells, weakening of sensitivity to sympathetic impulses.

In most of the vascular regions (myocardium, skeletal muscles, intestines, digestive glands), functional hyperemia is detected as a significant increase in total blood flow (up to a maximum of 4-10-fold) with increased organ function.
The brain also belongs to this group, although a general increase in its blood supply with increased activity of the "whole brain" has not been established, local blood flow in areas of increased neuronal activity increases significantly. Functional hyperemia is not found in the liver - the main chemical reactor of the body. Perhaps this is due to the fact that the liver is not in functional “rest”, and possibly due to the fact that it is already abundantly supplied with blood by the channel of the hepatic artery and portal vein. In any case, in another chemically active "organ" - adipose tissue - functional hyperemia is expressed.

There is functional hyperemia also in the kidney, working "non-stop", where the blood supply correlates with the rate of sodium reabsorption, although the range of changes in blood flow is small. With regard to the skin, the concept of functional hyperemia is not used, although the changes in blood supply caused by it occur constantly here. The main function of the body's heat exchange with the environment is provided by the blood supply to the skin, but other (not only heating) types of skin stimulation (ultraviolet irradiation, mechanical effects) are necessarily accompanied by hyperemia.

Table 7.5 also shows that all known mechanisms of regulation of regional blood flow (nervous, humoral, local) can also be involved in the mechanisms of functional hyperemia, and, in different combination for various organs. This implies the organ specificity of the manifestations of these reactions.

Nervous and humoral influences on organ vessels.
Claude Bernard in 1851 showed that unilateral transection of the cervical sympathetic nerve in a rabbit causes ipsilateral vasodilatation of the scalp and ear, which was the first evidence that the vasoconstrictor nerves are tonically active and constantly carry impulses of central origin, which determine the neurogenic component of resistance vessels.

At present, there is no doubt that neurogenic vasoconstriction is carried out by excitation of adrenergic fibers, which act on vascular smooth muscles by releasing the adrenaline mediator in the region of nerve endings. With regard to the mechanisms of vascular dilatation, the question is much more complicated. It is known that sympathetic nerve fibers act on vascular smooth muscle by reducing their tone, but there is no evidence that these fibers have tonic activity.

Parasympathetic vasodilator fibers of a cholinergic nature have been proven for a group of fibers of the sacral region, which are part of the n.pelvicus. There is no evidence for the presence of vagus nerves vasodilator fibers for the abdominal organs.

It has been proven that the sympathetic vasodilator nerve fibers of skeletal muscles are cholinergic. The intracentral pathway of these fibers, starting in the motor cortex, is described. The fact that these fibers can be fired upon stimulation of the motor cortex suggests that they are involved in a systemic response that increases skeletal muscle blood flow at the start of their work. The hypothalamic representation of this system of fibers indicates their participation in the emotional reactions of the body.

The possibility of the existence of a "dilator" center with a special system of "dilator" fibers is not allowed. Vasomotor shifts of the bulbospinal level are carried out exclusively by changing the number of excited constrictor fibers and the frequency of their discharges, i.e. vasomotor effects occur only by excitation or inhibition of the constrictor fibers of the sympathetic nerves.

Adrenergic fibers during electrical stimulation can transmit impulses with a frequency of 80-100 per second. However, special registration of action potentials from single vasoconstrictor fibers showed that in physiological rest the frequency of u "pulses in them is 1-3 per second and can increase only up to 12-15 impulses / s during the pressor reflex.

Maximum reactions of arterial and venous vessels are manifested at different frequencies of electrical stimulation of adrenergic nerves. Thus, the maximum values ​​of constrictor reactions of arterial vessels of skeletal muscles were noted at a frequency of 16 pulses/s, and the largest constrictor reactions of the veins of the same area occur at a frequency of 6-8 pulses/s. At the same time, “maximum reactions of the arterial and venous vessels of the intestine were noted at a frequency of 4-6 pulses/s.

From what has been said, it is clear that practically the entire range of vascular responses that can be obtained with electrical stimulation of the nerves corresponds to an increase in the frequency of impulses by only 1-12 per second, and that the autonomic nervous system normally functions at a discharge frequency significantly less than 10 impulses / s. .

Elimination of the "background" adrenergic vasomotor activity (by denervation) leads to a decrease in vascular resistance of the skin, intestines, skeletal muscles, myocardium and brain. For kidney vessels, a similar effect is denied; for vessels of skeletal muscles, its instability is emphasized; for the vessels of the heart and brain, a weak quantitative expression is indicated. At the same time, in all these organs (except the kidney) by other means (for example, the administration of acetylcholine) it is possible to cause an intense 3-20-fold (Table 7.6) persistent vasodilation. Thus, the general pattern of regional vascular reactions is the development of a dilator effect during denervation of the vascular zone, however, this reaction is small in comparison with the potential ability of regional vessels to expand.

Table 7.6 Maximum increase in blood flow in the vessels of various organs.
Organ	Initial blood flow, (ml min -1 x (100 g) -1 vasodilation 400	Multiplicity of blood flow increase at maximum 1.2
Myocardium	70	6.0
Salivary gland	55	2.8
Intestines	40	12.0
Liver	30	8.0
Leather	25	6.0
Fat	10	17.5
Skeletal muscle	6	24.0

Electrical stimulation of the corresponding sympathetic fibers leads to a sufficiently strong increase in the resistance of the vessels of the skeletal muscles, intestines, spleen, skin, liver, kidney, fat; the effect is less pronounced in the vessels of the brain and heart. In the heart and kidney, this vasoconstriction is opposed by local vasodilatory effects mediated by the activation of the functions of the main or special tissue cells simultaneously triggered by the neurogenic adrenergic mechanism. As a result of this superposition of the two mechanisms, the detection of adrenergic neurogenic vasoconstriction in the heart and kidney is more difficult than for other organs. The general pattern, however, is that in all organs, stimulation of sympathetic adrenergic fibers causes activation of vascular smooth muscles, sometimes masked by simultaneous or secondary inhibitory effects.

With reflex stimulation of the sympathetic nerve fibers, as a rule, there is an increase in vascular resistance in all studied areas (Fig. 7.21).

On the y-axis - changes in resistance as a percentage of the original; along the abscissa:
1 - coronary vessels,
2 - brain,
3 - pulmonary,
4 - pelvis and hind limbs,
5 - hind limb,
6 - both hind limbs,
7 - pelvic muscles,
8 - kidneys,
9 - large intestine,
10 - spleen,
11 - forelimb,
12 - stomach,
13 - ileum,
14 - liver.

When inhibited by sympathetic nervous system(reflexes from the cavities of the heart, depressor sinocarotid reflex), the opposite effect is observed. Differences between the reflex vasomotor reactions of organs, mainly quantitative, qualitative, are found much less frequently. Simultaneous parallel registration of resistance in various vascular areas indicates a qualitatively unambiguous nature of the active reactions of vessels under nervous influences.

Considering the small value of reflex constrictor reactions of the vessels of the heart and brain, it can be assumed that under natural conditions of blood supply to these organs, sympathetic vasoconstrictor effects on them are leveled by metabolic and general hemodynamic factors, as a result of which, the end effect may be the expansion of the vessels of the heart and brain. This overall dilator effect is due to a complex set of influences on these vessels, and not only neurogenic ones.

Cerebral and coronary departments vascular system provide metabolism in vital organs therefore, the weakness of vasoconstrictor reflexes in these organs is usually interpreted, meaning that the predominance of sympathetic constrictor influences on the vessels of the brain and heart is biologically inappropriate, since this reduces their blood supply. Vessels of the lungs, performing a respiratory function aimed at providing oxygen to organs and tissues and removing carbon dioxide from them, i.e. function, the vital importance of which is indisputable, on the same basis "should not" be subjected to pronounced constrictor influences of the sympathetic nervous system. This would lead to a violation of their basic functional value. The specific structure of the pulmonary vessels and, apparently, because of this, their weak response to nerve influences can also be interpreted as a guarantee of the successful provision of the oxygen demand of the body. Such reasoning could be extended to the liver and kidneys, the functioning of which determines the vitality of the organism in a less "emergency" but no less responsible way.

At the same time, with vasomotor reflexes, the narrowing of the vessels of the skeletal muscles and abdominal organs is much greater than the reflex reactions of the vessels of the heart, brain, and lungs (Fig. 7.21). The similar value of vasoconstrictor reactions in skeletal muscles is greater than in the celiac region, and the increase in the resistance of the vessels of the hind limbs is greater than that of the vessels of the forelimbs.

The reasons for the unequal severity of neurogenic reactions of individual vascular zones may be:
1. different degree of sympathetic innervation;
2. quantity, distribution in tissues and vessels and sensitivity A- and B-adrenergic receptors;
3. local factors (especially metabolites); biophysical features of vessels;
4. uneven intensity of impulses to different vascular areas.

Not only quantitative, but also qualitative organ specificity has been established for the reactions of accumulating vessels. In case of pressor carotid sinus baroreflex, for example, the regional vascular pools of the spleen and intestines equally reduce the capacity of the accumulating vessels. However, this is achieved by the fact that the regulatory structure of these reactions is significantly different: veins small intestine almost completely realize their effector capabilities, while the veins of the spleen (and skeletal muscles) still retain 75-90% of their maximum capacity for constriction.

So, with pressor reflexes biggest changes vascular resistances were noted in the skeletal muscles and smaller ones in the organs of the splanchnic region. Changes in vascular capacity under these conditions are reversed: maximum in the organs of the splanchnic region and smaller in skeletal muscles.

The use of catecholamines shows that in all organs, activation A- adrenoreceptors is accompanied by constriction of arteries and veins. Activation B — adrenoreceptors (usually their connection with sympathetic fibers is much less close than that of a-adrenergic receptors) leads to vasodilation; for the blood vessels of some organs, B-adrenergic reception was not detected. Therefore, in qualitative terms, regional adrenergic changes in the resistance of blood vessels are primarily of the same type.

A large number of chemical substances causes active changes in the lumen of blood vessels. The concentration of these substances determines the severity of vasomotor reactions. A slight increase in the concentration of potassium ions in the blood causes dilatation of blood vessels, and with more high level- they narrow, calcium ions cause arterial constriction, sodium and magnesium ions are dilators, as well as mercury and cadmium ions. Acetates and citrates are also active vasodilators, chlorides, biphosphates, sulfates, lactates, nitrates, bicarbonates have a much lesser effect. Ions of hydrochloric, nitric and other acids usually cause vasodilation. direct action adrenaline and norepinephrine on the vessels causes mainly their constriction, and histamine, acetylcholine, ADP and ATP - dilation. Angiotensin and vasopressin are strong local vascular constrictors. The influence of serotonin on the vessels depends on their initial tone: if the latter is high, serotonin dilates the vessels and, conversely, with a low tone, it acts as a vasoconstrictor. Oxygen can be highly active in organs with intensive metabolism (brain, heart) and have a much lesser effect on other vascular areas (eg, limbs). The same applies to carbon dioxide. A decrease in the concentration of oxygen in the blood and, accordingly, an increase in carbon dioxide leads to vasodilation.

On the vessels of skeletal muscles and organs of the celiac region, it was shown that under the action of various vasoactive substances, the direction of the reactions of arteries and veins in the organ can be either the same in nature or different, and this difference is provided by the variability of venous vessels. At the same time, the vessels of the heart and brain are characterized by an inverse relationship: in response to the use of catecholamines, the resistance of the vessels of these organs can change differently, and the capacity of the vessels always unequivocally decreases. Norepinephrine in the vessels of the lungs causes an increase in capacity, and in the vessels of the skeletal muscles - both types of reactions.

Serotonin in the vessels of the skeletal muscles leads mainly to a decrease in their capacity, in the vessels of the brain - to its increase, and in the vessels of the lungs both types of changes take place. Acetylcholine in skeletal. in the muscles and brain, it mainly reduces the capacity of the vessels, and in the lungs it increases it. Similarly, the capacity of the vessels of the brain and lungs changes with the use of histamine.

The role of vascular endothelium in the regulation of their lumen.
Endotheliumvessels has the ability to synthesize and secrete factors that cause relaxation or contraction of vascular smooth muscles in response to various kinds of stimuli. The total mass of endotheliocytes, monolayer lining blood vessels from within (intimacy) in humans, it approaches 500 g. The total mass, high secretory ability of endothelial cells, both “basal” and stimulated by physiological and physico-chemical (pharmacological) factors, allows us to consider this “tissue” as a kind of endocrine organ (gland). Distributed throughout the vascular system, it is obviously intended to transfer its function directly to the smooth muscle formations of the vessels. The half-life of the hormone secreted by endotheliocytes is very short - 6-25 s (depending on the type and sex of the animal), but it is able to contract or relax the smooth muscles of the vessels without affecting the effector formations of other organs (intestines, bronchi, uterus).

Endotheliocytes are present in all parts of the circulatory system, however, in the veins, these cells have a more rounded shape than arterial endotheliocytes elongated along the vessel. The ratio of the length of the cell to its width in the veins is 4.5-2:1, and in the arteries 5:1. The latter is associated with differences in blood flow velocity in the indicated sections of the organ vascular bed, as well as with the ability of endothelial cells to modulate the tension of vascular smooth muscles. This capacity is correspondingly markedly lower in veins than in arterial vessels.

The modulating effect of endothelial factors on vascular smooth muscle tone is typical of many mammalian species, including humans. There are more arguments in favor of the "chemical" nature of the transmission of the modulating signal from the endothelium to vascular smooth muscle than its direct (electrical) transmission through myoendothelial contacts.

secreted by the vascular endothelium, relaxing factors (HEGF) - unstable compounds, one of which, but far from the only one, is nitric oxide (No). The nature of the vascular contraction factors secreted by the endothelium has not been established, although it may be endothelium, a vasoconstrictor peptide isolated from porcine aortic endotheliocytes and consisting of 21 amino acid residues.

It has been proven that this “locus” is constantly supplied to smooth muscle cells and to the circulating blood by VEGF, which increases with the rape type of pharmacological and physiological influences. The participation of the endothelium in the regulation of vascular tone is generally recognized.

The sensitivity of endotheliocytes to blood flow velocity, which is expressed in their release of a factor that relaxes vascular smooth muscles, leading to an increase in the lumen of the arteries, was found in all studied mammalian main arteries, including humans. The relaxation factor released by the endothelium in response to a mechanical stimulus is a highly labile substance that does not fundamentally differ in its properties from the mediator of endothelium-dependent dilator reactions caused by pharmacological substances. The latter position states the “chemical” nature of signal transmission from endothelial cells to smooth muscle formations of vessels during the dilator reaction of arteries in response to an increase in blood flow. Thus, the arteries continuously adjust their lumen according to the speed of blood flow through them, which ensures the stabilization of pressure in the arteries in the physiological range of changes in blood flow values. This phenomenon is of great importance in the development of working hyperemia of organs and tissues, when there is a significant increase in blood flow; with an increase in blood viscosity, causing an increase in resistance to blood flow in vasculature. In these situations, the mechanism of endothelial vasodilation can compensate for an excessive increase in resistance to blood flow, leading to a decrease in tissue blood supply, an increase in the load on the heart, and a decrease in cardiac output. It is suggested that damage to the mechanosensitivity of vascular endotheliocytes may be one of the etiological (pathogenetic) factors in the development of obliterating endoarteritis and hypertension.

They diagnose many diseases of the brain using various hardware methods, and then, if necessary, prescribe treatment and rehabilitation. One of the methods for diagnosing cerebral vessels is transcranial dopplerography.

The technique of non-invasive ultrasound examination of intracranial arteries directly through the scalp was proposed by R. Aslid in 1982 and opened up great opportunities for neurology and neurosurgery for the clinical study of intracranial arteries, which made it possible to take a new step forward in the study of the vascular system of the brain in normal and pathological conditions (vascular insufficiency). , stroke, HNMK, VVD, stroke, etc.). Ultrasonic devices, used in Doppler sonography, work on the principle of the Doppler effect, which consists in changing the frequency of an ultrasonic signal when it is reflected from any moving object, for example, from blood cells (Fig. 1).

Part of the ultrasonic radiation is reflected by various tissues in the human body and is received by a crystal located in the sensor. Upon contact of the sensor with the skin, an acoustic paste is applied, because. ultrasound, passing through the air changes. The ultrasonic signal reflected from moving erythrocytes is shifted in frequency by an amount proportional to the speed of their movement. The frequency distribution of the Doppler signal depends on the uneven movement of erythrocytes through the vessel, the distance between blood cells and some other factors.

The first reports on the application of the Doppler principle for measuring blood flow velocity belong to Satomura (1960), Franclin (1961). Over the next few years, Doppler ultrasound devices have been greatly improved. The use of the flow direction detector (McLeod, 1968; Beker, 1969) has greatly expanded the diagnostic possibilities. In the 70s, the method of "spectral analysis" of the Doppler signal was proposed, which made it possible to quantify the degree of stenosis carotid arteries. In the same years, in parallel with the development of constant-wave Doppler systems, systems with pulsed radiation were introduced. The combination of the latter with spectral analysis and echoscopy in "B" mode has led to the creation of duplex systems.

1982 is the starting point for transcranial Doppler sonography (TDG). The first clinical results of this method were published by R. Aaslid in this year. Transcranial dopplerography made a breakthrough in the diagnosis of occlusive lesions of the brachiocephalic arteries, allowing the diagnosis of intracranial lesions, which until then were considered inaccessible to ultrasound. For TDG, a pulsed mode of operation of the sensor is used (Fig. 2).

All signals of Doppler devices have certain characteristics, each of which should be used as much as possible in the diagnosis of vascular lesions: amplitude, direction of blood flow and its phase, frequency distribution, source location, power distribution within the spectrum frequencies. The total amplitude is the least reliable indicator, as it depends on many factors unrelated to the blood flow velocity. Power distribution is important characteristic for diagnostics.

The maximum frequency of the upper end of the spectrum is the most used characteristic when comparing symmetrical arteries or a single artery along the vessel. Due to the fact that the blood flow velocity along the course of the vessel changes periodically, the display of the spectral distribution is of great value, and the appearance of the sound spectrum contributes to a more accurate analysis of the received signal. The direction of blood flow is determined using the phase value of the Doppler shift. To designate the direction of blood flow in the literature, several terms are accepted: “forward”, “anterograde” - indicate the normal direction of blood flow; "reverse", "retrograde" - this is movement in an abnormal direction, "bidirectional" blood flow - signals begin either with a positive or negative direction; "biphasic" - the direction of blood flow changes during the cardiac cycle, "double" direction - refers to blood flow moving in two directions at the same time, i.e. with turbulence.

The first stage in the study of cerebral vessels using the TCD method is to determine and fix the optimal position of the doctor and the patient, since at least half of the unsuccessful studies can be attributed to the forced position of the doctor during work. The study is carried out with horizontal position the patient on his back with a small pillow under his head, stomach or side. The doctor is located on the side of the head (possibly behind the head), the device is in front of him with a convenient location of the sensor in his hand.

The next important step in the transcranial examination technique is to determine the place on the skull (ultrasonic window) through which the ultrasound signal can easily pass through the bone without significant attenuation and receive the Doppler signal from the intracranial arteries (Fig. 3).

At present, it is known that the TCD method can be successfully used in everyday neurological and angioneurosurgical practice. This study of cerebral vessels is widely used to diagnose atherosclerotic lesions of intracranial arteries, detect aneurysms and arteriovenous malformations, determine spasm of cerebral arteries and dynamically monitor them during treatment, for an objective assessment of the functional reserve of cerebral vessels and other changes.

Diagnostics of TKD is based on the principles of assessing LBFV in arterial lesions, taking into account changes in hemodynamics in the pre- and post-stenotic zone, assessment of the anatomical and functional state of the collateral circulation, indicators of blood flow velocities and their asymmetry. The leading indicator for the diagnosis of TCD is a change in the rate of blood flow through the intracranial arteries compared to the norm (Table 1).

Table 1

The main Doppler indicators of blood flow in the intracranial arteries of healthy people (V. Rotenberg. 1987)

Artery, depth (mm)	Age	Doppler indicators
		Vmax (cm/s)	Vmed (cm/s)	Vd (cm/s)	R.I.	PI
CMA 45-65	< 40	94.5±13.6	58.4±8.4	45.6±6.6	0.55±0.16	0.83±0.21
	40-60	91.0±16.9	57.7±11.5	44.3±9.5	0.50±0.17	0.86±0.14
	> 60	78.1±15.0	4.7±11.1	31.9±9.1	0.45±0.14	1.03±0.18
PMA 65-75	< 40	76.4±16.9	47.3±13.6	36.0±9.0	0.53±0.18	0.85±0.20
	40-60	85.4±20.1	53.1±10.5	41.1±7.4	0.50±0.15	0.85±0.18
	> 60	73.3±20.3	45.3±13.5	34.2±8.8	0.47±0.17	0.86±0.16
ZMA 60 - 75	< 40	53.2±11.3	34.2±7.8	25.9±6.5	0.55±0.16	0.79±0.22
	40-60	60.1±20.6	36.6±9.8	28.7±7.5	0.53±0.14	0.85±0.17
	> 60	51.0±11.9	29.9±9.3	22.0±6.9	0.51±0.16	0.96±0.14
PA 45-80 OA 80-100	< 40	56.3±7.8	34.9±7.8	27.0±5.3	0.52±0.16	0.83±0.23
	40-60	59.5±17.0	36.4±11.7	29.2±8.4	0.49±0.12	0.84±0.19
	> 60	50.9±18.7	30.5±12.4	21.2±9.2	0.48±0.14	0.97±0.20

Note: MCA - middle cerebral artery, ACA - anterior cerebral artery, PCA -0 posterior cerebral artery, VA - vertebral artery, OA - basilar artery

They are fundamentally important for diagnostics, since they determine the boundaries of the possible normal range of blood flow rates, beyond which may be associated with pathological changes in the vessels. In this case, it is necessary to take into account the age of the subject, indicators of blood rheology.

When analyzing the received Dopplerogram for the subsequent assessment of the linear velocity of blood flow and other blood flow parameters, in addition to audio and visual information evaluation, a number of parameters and indices are calculated:

• Vmed is the average blood flow velocity in systole;
• Vmax is the maximum systolic amplitude, reflecting the highest systolic blood flow velocity at the location point;
• Vd is the end diastolic blood flow velocity;

Vmax is the main criterion for carotid Doppler sonography. Its increase above normal values ​​indicates the presence of stenosis in the area of ​​the artery location.

An increase in Vd above normal values ​​indicates the presence of stenosis, and a decrease indicates an increase in circulatory resistance in the basin of the located artery.

SB (spectrum broadening) or spectral broadening index characterizes the degree of blood flow turbulence at the location.

This index is calculated using the formula:

SB = (Vmax-A)/Vmax

where A is the velocity of the maximum flow intensity.

To characterize circulatory resistance, the Purcelo index (RI) is calculated, which is the ratio of the difference between the maximum systolic and final diastolic velocities to the maximum systolic velocity, also reflects the state of blood flow resistance distal to the measurement site.

The Stewart index (ISD) is also used - a systolic-diastolic indicator that reflects the elastic properties of blood vessels and changes with age. It is calculated by calculating the ratio between the maximum and minimum blood flow velocity.

PI - pulsation index (Gosling index), is the ratio of the difference between the maximum systolic and diastolic velocities to the average velocity, reflects the elastic properties of the arteries and decreases with age.

To determine the percentage of vessel stenosis, the Arbeli index (STI) can be used, which reflects the degree of narrowing of the arteries with stenoses of more than 50% (relative index). Here, the ratio between the blood flow velocities in the stenosis zone and in the post-stenotic area with normalized blood flow is calculated. With the predominance low speeds blood flow, which is typical for turbulent flow, the SB index increases above normal values.

Transcranial diagnostics of intracranial arteries located on the basis of the brain requires the researcher to be proficient in the technique of ultrasonic location, knowledge of the anatomical and functional variants of the structure and development of blood vessels, LBF norm indicators, experience in compression tests and knowledge of the signs accompanying the lesion of each of the arteries. Only after that it is possible to proceed to the diagnosis of lesions of individual sections of intracranial vessels. TKD uses a transducer with a frequency of 2 MHz and includes a study in the ophthalmic, supratrochlear, internal carotid, anterior, middle and posterior cerebral, vertebral and basilar arteries through the main "windows": temporal, orbital, suboccipital. Identification criteria:

1. Depth and angle of sounding.

3. Response of blood flow to compression of the common carotid artery (CCA).

temporal window is considered the main one, since through it the study of the final sections of the internal carotid artery, the initial segments of the middle, anterior, posterior cerebral arteries is performed. In scales temporal bone It is customary to conduct a study through the anterior, middle and posterior temporal windows. The anterior window is located above the zygomatic arch closer to the orbital bone, the posterior anterior auricle, and the average between them. It is possible to locate the intracranial arteries through any of these windows, however, due to the small size of these arteries and the difficulty of focusing the beam, it is sometimes necessary to sequentially locate the arteries through all three windows, selecting the most stable signal.

MCA, ACA, PCA, ICA are located through the temporal window (anterior, middle, posterior) (Fig. 4). After the optimal position of the sensor has been found, it is possible to start locating the ICA siphon. The blood flow here is detected at a depth of 65–75 mm, the sensor beam is directed to the lower edge of the opposite eye. Bidirectional blood flow is recorded in the area of ​​the siphon or bifurcation of the ICA. Compression of the homolateral CCA leads to a weakening or reduction of the received signal, a change in the direction of blood flow, and causes compensatory blood flow from the contralateral ICA through the PCA.

Further, changing the depth, locate the M1 segment of the middle cerebral artery(SMA). SMA is the largest branch and a direct continuation of the ICA. MCA is subdivided into segments M1, M2, M3, M4 - the first two of which are accessible to ultrasound location. The M1 segment is located horizontally almost at a right angle to the area of ​​the temporal bone on which the sensor is installed. SMA brings to the cerebral hemisphere up to 80% of the required blood volume. The cortical branches of the MCA widely anastomose with the cortical branches of the ACA and PCA. The MCA is located at depths from 45 to 65 mm; a little deeper one can detect the bifurcation of the ICA. The blood flow in the MCA in healthy individuals is directed to the transducer at an almost zero angle. In addition to the study of blood flow through the MCA at rest, tests with clamping of the ipsi- and contralateral CA are performed to study the effectiveness of collateral blood flow through the circle of Willis and identify signs of subocclusion / occlusion of the ipsilateral CA, as well as a 30-second breath-hold test and a 30-second test with hyperventilation to assess cerebrovascular reactivity

With stenosis of the MCA, there is an increase in the linear velocities of blood flow, with severe stenosis, the diastolic velocity is greatest with a decrease in the systolic-diastolic ratio, and blood flow is accelerated at the site of stenosis. A “shaggy” Dopplerogram is visualized with a shift in the maximum spectral power to the low-frequency region, manifestations of post-stenotic turbulence. Stenoses less than 50% of the lumen do not cause perceptible changes in the Dopplerogram. Dopplerography does not accurately determine the degree of stenosis. In MCA stenosis, accompanied by a decrease in cerebrovascular reactivity, there are indications for an extra-intracranial anastomosis (in the absence of pronounced postischemic changes in the brain tissue). In other cases, conservative therapy is undertaken.

PMA is also a branch of the BCA. PSA binds the right and left ACA, and it can be detected by Dopplerography only when performing a compression test. Two ACA and PSA form the anterior carotid section of the arterial (Willisian) circle big brain(Fig.5).

The location of the ACA is carried out at a depth of 65-75 mm when the sensor is located in the posterior temporal fenestra and the beam is directed anteriorly. The blood flow in the ACA in healthy individuals is directed away from the sensor. In addition to the study of blood flow through the ACA at rest, a test with clamping of the ipsilateral CA is performed to study the closure of the circle of Willis in front.

ZMA is formed during the separation of OA. There are several anatomical options for the discharge of the PCA. It may be the final branch of the OA, one PCA may originate from the ICA, the other from the OA, both arteries on one side, both from the ICA, one PCA may originate from the other. The cortical branches of the PCA anastomose on the surface of the brain with the cortical branches of the SCA and ACA. ACA connects the ACA to the ICA.

The PCA is examined with the patient lying on his back through the posterior "temporal window" at depths of 60-75 mm, directing the beam posteriorly. In healthy individuals, the blood flow in the proximal part of the PCA is directed towards the sensor, and in the distal part, away from the sensor. In addition to the study of blood flow through the PCA at rest, a test with clamping of the ipsilateral CA is performed to study the closure of the circle of Willis at the back.

At orbital approach can be located ophthalmic artery, NBA, carotid siphon, C1 region of the ICA. The main artery that is examined in this approach is the NMA, which originates from the ophthalmic artery. The ophthalmic artery arises from the medial side of the anterior bulge of the ICA siphon. It enters the eye socket through a canal optic nerve and on the medial side of the orbit divides into its terminal branches. Through the branches of the ophthalmic artery, anastomosis is carried out between the ICA and ECA systems. The 8 MHz transducer is placed in the medial corner of the orbit and the beam is directed to the chiasm region.

Normally, the blood flow in the supratrochlear artery is antegrade (i.e. from the cranial cavity to skin) and directed towards the sensor. Several tests are carried out, sequentially clamping the ipsilateral, contralateral CCA, branches of the ECA on the side of the study, as well as the branches of the ECA on the contralateral side. Normally, compression of the ipsilateral CCA leads to a reduction in blood flow in the supratrochlear artery, which indicates the patency of the internal carotid artery; when the contralateral CCA is clamped, the LBFV in the IMA increases or does not change, which indicates the normal functioning of the PSA. With occlusion of the ICA, the blood flow in the IMA changes to retrograde, which may indicate the inclusion of an ophthalmic anastomosis. Further, it is possible to locate the ophthalmic artery, with a location depth of 45-55 mm, a radiation power of 15-30%, the location of the sensor in the middle of the lower eyelid and the direction of the beam to the upper orbital fissure. By increasing the location depth to 60-75 mm, it is possible to find the cavernous and cisternal segments of the carotid siphon. By moving the transducer to the outer eyelid and directing the beam medially, the C1 segment of the ICA can be detected.

Suboccipital window is the main one for the study of the vertebrobasilar basin. Through this approach, it is possible to locate the intracranial part vertebral artery, the main artery throughout and the posterior cerebral arteries.

The vertebral artery (VA) is a branch subclavian artery. On the right, it begins at a distance of 2.5 cm, on the left - 3.5 cm from the beginning of the subclavian artery. PA is divided into 4 parts. Initial (segment V1), - located behind the anterior scalene muscle, goes up, enters the opening of the transverse process of the 6th (less often 4-5 or 7) cervical vertebra. Neck part artery (segment V2) passes through the canal formed by the transverse processes of the cervical vertebrae and rises. Having exited through the opening in the transverse process of the 2nd cervical vertebra (segment V3), it goes posteriorly and laterally (1st bend), heading for the opening of the transverse process of the atlas (2nd bend), then turns to the dorsal side of the atlas (3rd bend), then turning medially and reaching the foramen magnum (4th bend), it passes through the atlanto-occipital membrane and hard meninges into the cranial cavity. Further, the intracranial part (V4 segment) goes to the base of the brain laterally from medulla oblongata and then anterior to it. Both PAs at the border of the medulla oblongata and the pons merge into one unpaired OA. Approximately in half of the cases, one or both VAs have an S-shaped bend before the moment of fusion, which is associated with multidirectional blood flow in its segments. The study of PA with TKD is carried out with a 2 MHz sensor in the V3 segment. The subject is in the supine position. The head is tilted slightly back and turned in the opposite direction to the examined artery so that the common carotid arteries are easily accessible for clamping. The sensor is installed in the area bounded from above by the mastoid process, in front - by the sternocleidomastoid muscle, while the beam is directed to the opposite orbit of the eye. Location depth 45-80 mm. By moving the sensor, the maximum signal is achieved, after which it is identified, since in this area, in addition to the vertebral artery, branches of the external carotid artery can be located. VA is identified by tapping on the VA projection in the brachiocephalic region (V1 segment). A short-term compression of the common carotid artery is also performed from the side of the study. A test for the functioning of the posterior communicating artery is performed when registering blood flow through the vertebral artery, pinching the homolateral common carotid artery for 1–2 s. If at the same time there is an increase in the speed of blood flow through the vertebral artery, then the homolateral posterior communicating artery is functioning (positive test), if there are no changes, then the communicating artery is not functioning (negative test).

If you suspect subclavian steal syndrome a reactive hyperemia test is performed. Using a sphygmomanometer cuff, compression of the shoulder is performed for 1.5-2 minutes, followed by rapid decompression. Normally, the blood flow does not change ( negative test). If after decompression of the shoulder there is an accelerated blood flow through the VA, this is positive test reactive hyperemia, and increased blood flow has a retrograde direction. There are three types of subclavian steal syndrome:

1. Constant, in case of occlusion of the subclavian artery orifice and/or the orifice of the VA — the blood flow in the VA is constantly retrograde, increases when performing the reactive hyperemia test.

2. Transient, with severe stenosis of the orifice of the subclavian artery or/and the orifice of the VA - retrograde blood flow along the VA in systole, anterograde - in diastole.

3. Latent, with moderate stenosis of the orifice of the subclavian artery or/and the orifice of the VA — anterograde blood flow through the VA at rest and a positive test result.

For stenosing changes in the vertebral artery the presence on the side of the lesion of the following deviations in the spectrogram indicators is characteristic:

1) a decrease in the peak of the impulse velocity of blood flow through the vertebral artery, its blurring;

2) decrease in the diastolic component of the blood flow velocity in the vertebral artery;

3) change in the audio characteristics of the recorded sound signals of the blood flow velocity;

4) change in spectral characteristics: spread of the high-frequency spectrum, closing of the spectral window, concentration of brightness in the low-frequency zone, etc.

5) asymmetry of blood flow velocity in the vertebral arteries of more than 50% (possible with developmental variants);

6) increased blood flow velocity in the vertebral artery during compression of the homolateral shoulder by the inflated cuff of the tonometer, followed by the return of the velocity to the initial values ​​after decompression of the cuff.

The concept of normal blood flow velocity for the carotid and vertebral arteries, strictly speaking, is somewhat arbitrary, because. you can never accurately determine the angle of the location of the artery.

When researching basilar artery several options for the location of the patient are possible: lying on his stomach or on his side, sitting on a chair with his head down.

The main artery is formed by the confluence of two vertebral arteries at the posterior edge of the pons varolii, then it lies on the anterior surface of the pons varolii, adjoins the clivus, goes forward, upwards and at the level of the anterior edge of the pons is divided into two terminal branches - the posterior cerebral arteries, also OA gives branches of the anterior inferior and superior cerebellar arteries.

In some cases, variants of the anatomical structure of the OA are observed, which are associated with the peculiarities of its location: high formation of a short OA, partial fusion of the VA with the formation of "islands", and in rare cases, there is no fusion of the VA and two parallel trunks stretch along the bridge, which directly pass into the PCA or ZSA.

When locating the basilar artery, the transducer is placed along middle line below the posterior edge of the large occipital foramen of the occipital bone and direct the ultrasound beam under it. The search for a signal is started at a depth of 60 - 80 mm, successively changing the angle of inclination and the position of the sensor on the skin surface, increasing the depth, and also increasing the opening angle of the window slit by pressing the patient's chin to the chest. After the appearance of a stable signal from the main artery and the recording of spectrograms, it is possible, by increasing the depth, to continue the location of the already distal part of the artery, including the bifurcation.

The location of the posterior cerebral artery can, if necessary, be performed from the suboccipital window. To do this, when examining the main artery, it is necessary to “reach” its distal section and locate the bifurcation area, which will manifest itself in a change in the sound and spectral characteristics of the signal - coarse noise and an increase in low frequencies in the spectrum. After that, by slowly changing the angle and increasing the depth of location (90-110 mm), you can get a clear spectrogram.

Examination of the connecting arteries of the arterial circle. The main collateral source of the human brain, which provides instant compensation for cerebral circulation in case of its violation, is the circle of Willis or the arterial circle of the cerebrum. known various options its structure, but the normal standard structure of the circle of Willis is found only in 30-50% of the subjects. There are two divisions in the circle of Willis: anterior and posterior. The anterior section includes the proximal segments of both anterior cerebral arteries and the anterior communicating artery, which is an anastomosis between both carotid pools. The posterior section of the great arterial ring is formed by the initial segments of the PCA and is closed by two posterior communicating arteries.

The anterior communicating artery may be poorly developed, but its absence is extremely rare.

The inclusion of collateral circulation occurs with stenosis or thrombosis of the arteries of the brain and is the fastest and most effective link in compensation. The development of cerebrovascular diseases and the occurrence of cerebrovascular accidents are accompanied by changes and restructuring of blood vessels, therefore, information about the state of the vessels of the circle of Willis is very important for specialists and helps to assess the possibilities of cerebral hemodynamics. Tests for the functional state of the anterior and posterior communicating arteries are carried out using functional compression tests. Compression of the common carotid artery should be carried out as low as possible on the neck to exclude an irritating effect on the carotid glomerulus (bradycardia, arrhythmia), as well as compression of an atherosclerotic plaque (risk of arterio-arterial embolism). The usual duration of CCA compression is 2-3 seconds. With correctly performed compression of the common carotid artery, no complications are observed, and this simple method is of decisive importance both for identifying intracranial branches and for studying the state of collateral circulation.

A lot of experience is required to carry out this procedure and evaluate the result. The study of the anterior communicating artery is carried out in two stages: first, the blood flow velocity in the supratrochlear artery is recorded from both sides and the contralateral common carotid artery is compressed for 2-3 seconds. An increase in the velocity of blood flow in the NMA on at least one side indicates the functioning of the anterior communicating artery. In the absence of an increase in LBF in the NBA, they proceed to the second stage and register the blood flow in the internal carotid artery during clamping of the contralateral CCA. The absence of increased blood flow in the ICA indicates non-functioning of the anterior communicating artery.

Also, a test for the functioning of the anterior communicating artery can be carried out at the location of the ACA, clamping the ipsilateral CCA. If the anterior communicating artery functions when the ipsilateral CCA is clamped, an inversion of the blood flow through the ACA occurs, since blood flow from the contralateral carotid pool through the contralateral ACA and PCA begins with retrograde filling of the proximal ACA on the side of the study for the purpose of collateral blood supply to the main artery of the base of the brain - MCA.

A test for the functioning of the posterior communicating artery is performed when registering blood flow through the vertebral artery, while clamping the homolateral CCA. If at the same time the speed of blood flow along the vertebral artery increases, then the homolateral posterior communicating artery functions, if there are no changes, it does not function.

Also, a test for the functioning of the posterior communicating artery is carried out at the location of the posterior cerebral artery. When clamping the ipsilateral CA, there is an increase in the linear blood flow velocities (systolic, mean, diastolic) along the PCA, which indicates that the circle of Willis is closed posteriorly on the side of the study. There is an acceleration of blood flow through the PCA due to the discharge of blood through the ipsilateral PCA into the ipsilateral carotid pool for the purpose of its collateral blood supply. If the circle of Willis is not closed posteriorly on the side of the study (ipsilateral PCA is functionally incapable), there is no reaction to clamping of the ipsilateral CCA.

Evaluation of the functional state of collateral circulation. When performing this test, the M1 segment of the MCA is mainly located, a stable signal is achieved, and then the CCA is clamped for 7-10 seconds. Under normal functional state collaterals of the circle of Willis, LFR in the MCA decreases by no more than 50% of the background record, while a fairly rapid increase in LFR is noted. In case of insufficiency of collateral circulation, there is no tendency to an increase in LBF in the MCA, and a more significant decrease in LBF in the MCA is noted.

In addition to the assessment of collaterals, the study of biogenic mechanisms of regulation is used. cerebral circulation. At healthy patients in response to clamping of the CCA, autoregulatory mechanisms are activated, consisting in the expansion of the pial arteries, which compensate for the deficiency of cerebral circulation. In this case, when the CCA clamping is interrupted, an “overshoot” is noted - an increase in the LSC in the MCA above the background level, which then returns to its original value within 5-6 seconds. There is a formula for calculating the overshoot coefficient. It is calculated by dividing the blood flow velocity after deocclusion by the background blood flow velocity. Since the MCA supplies blood to most of the hemisphere, the calculation of the overshoot coefficient is important. clinical significance in the diagnosis of vascular pathology.

Occlusion of the vessels of the base of the brain. With occlusions of the arteries of the base of the brain, focal neurological symptoms often develop. It is advisable to carry out ultrasonography both neck vessels (Fig. 6) and TCD.

Occlusion of the ICA in the area of ​​the siphon distal to the mouth of the ophthalmic artery on the side of the lesion is characterized by the following changes on the Dopplerogram:

1. decrease in LBF in homolateral and CCA and ICA compared with contralateral ones by 30% or more;

2. An increase in LBF in the homolateral supratrochlear artery and a pronounced reaction of increased blood flow during compression by 8-10 seconds of the homolateral temporal artery.

3. no changes in blood flow on the test of the functioning of the connecting arteries of the arterial circle.

For occlusion of the ICA siphon at the origin of the posterior communicating artery, the following changes in the doppletogram are typical on the side of the lesion:

1. increase in the index of circulatory resistance > 0.75.

2. decrease in LBF in the supratrochlear artery

3. a positive test for the functioning of the homolateral posterior communicating artery in the absence of signs of functioning of the anterior communicating artery.

MCA occlusion can occur in patients with various pathologies, including cerebrovascular pathology, however, its diagnosis by ultrasound is possible mainly in the acute stage of thrombosis, since as the collateral circulation is switched on, the reliability of the UDC method decreases. For occlusion of the MCA on the side of the lesion, the following changes on the Dopplerogram are characteristic:

1. The increase in the index of circulatory resistance according to the OCA is more than 0.75.

2. Absence of asymmetry of the blood flow velocity along the CCA, sometimes an increase on the side of the lesion.

3. Positive samples on the functioning of the anterior and posterior communicating arteries.

Diagnosis of occlusion of the intracranial vertebral artery is not difficult, but sometimes you have to do differential diagnosis reasons for the absence of a Doppler signal, which may be anatomical features location or excessive development of the subcutaneous fat layer and muscles. The following dopplerogram changes are characteristic:

1. Decrease in LBF on the side of the lesion, with its compensatory increase from the contralateral side.

2. Decrease in the diastolic component of the blood flow velocity.

3. Absence of LBF amplification response in a normally functioning vertebral artery.

4. Negative test for the functioning of the posterior communicating artery.

Occlusion of the basilar artery is uncommon. Since anatomically, it supplies the brainstem with blood, and with this pathology, there is an increasing stem neurological symptomatology and respiratory disorders. Timely diagnosis here it is extremely important, since active thrombolytic therapy can save the patient's life and avoid many complications. The following changes are detected on the dopplerogram:

1. A pronounced decrease in LBF in both vertebral arteries with the disappearance of the diastolic component.

2. Compensatory increase in blood flow in one or both CCAs.

3. Negative test for the functioning of the posterior communicating artery.

Cerebral circulation disorders. With the initial manifestations of circulatory insufficiency, blood flow compensation in individuals with an increased need for blood flow to the brain is not fully realized. In this situation, headaches may occur, memory worsens, sleep, concentration of attention, heaviness in the head, noise in the head, dizziness, and increased irritability appear. All these symptoms disappear after rest and exclusion of adverse conditions. The ultrasound method allows to detect on initial stages circulatory disorders, pronounced changes in the main arteries and the connecting arteries of the circle of Willis, especially in patients with increased blood pressure in combination with signs of atherosclerosis.

Patients with transient ischemic attacks often experience focal and cerebral neurological symptoms lasting up to 24 hours. Then there is a fairly rapid recovery of lost functions. The ultrasound method in this case reveals mainly occlusive lesions of the main arteries, much less often occlusive and stenosing changes in the arteries of the circle of Willis. Study of patients during the period acute violation cerebral circulation requires a particularly careful approach to the patient, since the results of the examination can decide tactics emergency treatment. Ultrasound is of particular importance in the diagnosis of brain death. In this case, in the main arteries of the head, a reverberant blood flow (forward-backward movement of blood) is recorded, which is characterized by the manifestation of a negative wave in the diastole phase and an acute wave in the systole phase on the dopplerogram of the carotid and vertebral arteries.

Duplex scanning of vessels of the circle of Willis. The duplex scanning technique is based on two main effects of ultrasound. The effect of real-time imaging of an artery is associated with the reflection of ultrasonic waves from the interface between two media with different acoustic densities. The second effect is based on the Doppler principle itself. Duplex scanning has a significant advantage over angiography, since the technique is non-invasive and allows you to more accurately detect small vascular lesions, assess the state of blood flow, and identify features of an atherosclerotic plaque. With the advent of new diagnostic capabilities, new technologies based on color Doppler mapping and the energy of the reflected Doppler signal have appeared. The main advantage of color staining of the flow in the lumen of the vessel is to facilitate the search and refinement of the location of vessels of various diameters, the features of their anatomical structure. Using the energy of the reflected Doppler signal makes it possible to visualize low-velocity flows with a clearer image of the internal contours of the studied vessels.

In the 1980s, the active introduction of the method of transcranial duplex examination of the arteries of the base of the brain into clinical practice began. The technique of transcranial duplex scanning allows obtaining and evaluating the anatomical structure of the circle of Willis, the direction of blood flow and its spectral characteristics, diagnosing occlusive lesions and spasm of the arteries of the circle of Willis, identifying aneurysms, and determining the presence of hypertension syndrome.

Similarly to transcranial dopplerography, scanning is carried out through three main accesses: transtemporal, transorbital, transoccipital. First, brain structures are visualized in B-mode. Through the transtemporal window, it is possible to obtain axial and coronary scans of the brain. In the scan through the midbrain, it is possible to visualize the image of the legs of the brain in the form of an echostructure of medium density, enveloping their posterior cerebral arteries. When the probe is tilted in the cranial direction, it is possible to scan the thalamus, the pineal gland, the third ventricle, and the interhemispheric fissure in the form of structures of increased echo density located along the midline.

In order to obtain information about anatomical structure arteries of the base of the brain go into the color flow mode. The image of the middle cerebral artery is a tubular structure directed vertically or at a slight angle with a red lumen, the anterior cerebral artery is visualized in the region of the interhemispheric fissure as a blue coding. The posterior cerebral artery, as mentioned above, has an arcuate shape and goes around the legs of the brain. Further, by recording the image of the blood flow between the anterior cerebral arteries, the middle and posterior cerebral arteries, the anatomical structure of the circle of Willis is assessed. If visualization is difficult, compression tests are performed. Also, a red-coded image of the distal part of the basilar artery is obtained through the transtemporal window.

When examining through the transoccipital ultrasound window, it is possible to obtain images of the vertebral arteries and the proximal segment of the basilar artery in blue coding. From the transorbital window, the ophthalmic artery and the siphon of the internal carotid artery are examined. The power of the device in this study must be reduced by 50-75% of the maximum. In B-mode, you can see directly the orbit, below the ophthalmic artery at a depth of 25-35 mm, the lumen of which is coded in red. At a depth of 50-60 mm, one can visualize the siphon of the internal carotid artery with a rounded shape of red color.

In addition to studying the anatomical course of the arteries of the base of the brain, a qualitative and quantification SDCH sequentially in each vessel. For a qualitative assessment of the spectrum configuration in the arteries, the amplitude of the systolic rise, the shape of the systolic apex, the depth of the incisura between the systolic and diastolic components, and the magnitude of the diastolic velocity are taken into account. Normally, the blood flow velocity in the anterior circle of Willis is higher than in the posterior. It should also be taken into account that with age, the rate of blood flow decreases, while the values ​​of the pulsator index and the index of peripheral resistance normally remain stable.

transcranial duplex scanning also allows you to register embolic signals in the studied arteries. The explanation for this phenomenon is that the intensity of the reflected ultrasonic signal depends on many factors, including the size of the particles being determined. However, it should be noted that finding microemboli is possible only if their size and acoustic signal differ from blood cells.

In recent years, the number of indications for surgical interventions on the main arteries of the extracranial region has increased significantly, in this regard, duplex diagnosis of occlusive lesions of the arteries of the base of the brain is very relevant for doctors of various profiles. Stenosis or occlusive lesions are more commonly seen in the siphon of the internal carotid artery, the middle cerebral artery, and the basilar artery. In the diagnosis of stenosis, the location of the blood flow is extremely important: directly at the site of narrowing, distal or proximal to it. Also, to assess the effectiveness of therapy and determine the timing of the operation, specialists need to diagnose arterial spasms, both at the time of its onset and development, and at the time of completion. The hemodynamic effect of arterial spasm is identical to arterial stenosis, which results in an increase in LBF. The severity of spasm is determined by the degree of increase in LBF in the middle cerebral artery (from 140 to 200 cm/s is assessed as an average severity, above 200 cm/s as a significantly pronounced spasm). The study of LBF blood flow in the arteries of the base of the brain makes it possible to study the dynamics of changes in LBF blood flow in patients with subarochnoid hemorrhage. It should be noted that the great advantage of transcranial examination of the arteries of the base of the brain in the diagnosis of spasm in comparison with the method of radiopaque angiography is non-invasiveness, and this technique also avoids subsequent angiography.

In recent years, the first steps have been taken in the application of a new technique ultrasound diagnostics— three-dimensional ultrasonic angiography, the principle of which is based on the use of the energy of the reflected Doppler signal to obtain an image of the organ under study and its vessels. Then all the obtained images are sent for processing to a computer unit and as a result, a three-dimensional image of the vascular structures is obtained, which provides complete information about the anatomical structure and nature of the blood flow of the vascular bed of the study area.

The study of the causes of cerebral ischemia made it possible to establish that in 90% of cases it is caused by extracranial arteries supplying blood to the head. The largest part pathological changes form carotid, subclavian and vertebral arteries (vertebral).

Timely detection of the segment responsible for the decrease in blood flow makes it possible to prevent a stroke and apply the most effective method of treatment.

What do the statistics say?

Statistical processing of data obtained during computed tomography, showed that in almost 1/3 of patients (26% alone and 3% in combination with other vessels) with ischemic stroke, the main focus is located in the vertebrobasilar area of ​​responsibility or the basin. It is formed by a bilateral vertebral artery, passing into the basilar (main).

According to clinical findings, transient ischemic attacks in this area occur 3–3.5 times more often than in other extracranial areas of the brain blood supply.

Cause of death from brain failure vessels in 57% of cases is an atherosclerotic process in the vertebral arteries. Clinical picture lesions associated with the peculiarities of their location, shape, participation in hemodynamics.

Anatomical features of the vertebral arteries

Normally, 30% of the required blood volume enters the brain through the vertebral arteries. Anatomy plays a significant role in creating conditions for narrowing the diameter of blood vessels.

The vertebral artery branches from the subclavian towards the central part of the inner edge of the scalene muscle in the neck.

It is important that no more than 1–1.5 cm remains to the adjacent mouth of the thyroid trunk, which is also a branch of the subclavian artery. This creates an additional mechanism of “stealing” (blood redistribution) in case of hypoplasia or stenosis of the vertebral artery.

Heading up, the artery at the level of the sixth cervical vertebra (less often the fifth) enters the protected bone canal formed by the spinous processes of the vertebrae.

It is customary to distinguish departments or segments of the vertebral artery:

• I - the entire area from VI to II of the cervical vertebrae, where the vessel leaves the hole;
• II - outside the canal at an angle of 450 deviates posteriorly and goes to the transverse process of the first cervical vertebra (atlas);
• III - passing through the opening of the atlas on his back side the artery forms loops, their role is to prevent blood flow disorders when turning the head;
• IV - heading into the foramen magnum, the artery is located inside a dense ligament, when the container is ossified or bone outgrowths on the occipital bone, conditions are created for traumatizing the walls of the vessel during movements in cervical region;
• V - inside the foramen magnum (intracranial segment), the vertebral artery passes through the dura and lies on the surface of the medulla oblongata.

The fusion of the left and right arteries into a single trunk (basilar artery) provides participation in the formation of the circle of Willis at the base of the brain

A feature is the compensatory development of blood circulation due to the vertebral artery on the one hand, if another symmetrical branch is clamped. The asymmetry of blood flow in the vertebral arteries is leveled by the flow of blood through the basilar artery into the undamaged part.

What is the most common anatomical pathology?

20% of cases of pathology of the vertebral arteries are due to developmental anomalies:

• discharge directly from the aorta;
• entry into the bone spinal canal is higher than usual (at the level of the third to fifth cervical vertebrae);
• displacement of the mouth towards the outside.

More often, lesions are combined in nature and are divided into the following options:

• up to 34% is due to the combined effect of developmental anomalies and extravasal muscle compression;
• 39% are stenoses of atherosclerotic and thrombotic nature;
• the maximum part - 57% - is represented by compression by various displacements of the vertebrae in combination with atherosclerosis.

The main causes and relationship with the localization of damage

All causes of the pathology of the vertebral arteries are divided into 2 large groups:

• vertebrogenic,
• nonvertebrogenic.

Vertebrogenic are caused by the impact of changes in the spine. IN childhood most often found:

• developmental anomalies;
• injuries in the cervical region (including those received during childbirth);
• pathological muscle spasm with severe hypothermia, torticollis.

In adults, there are more associations with diseases of the vertebrae:

• osteochondrosis;
• ankylosing spondylitis;
• tumors.

Injuries also matter.

Altered lateral processes of the vertebrae take part in the compression of the artery

Non-vertebrogenic are represented by three groups of diseases:

• causing stenosis of the lumen of the arteries (inflammatory arteritis, thrombosis, atherosclerosis, embolism);
• contributing to the violation of the shape and direction of the vessels (kinks, non-rectilinear course from the sixth to the second vertebra, increased tortuosity);
• as a consequence of compression from the outside (spastic muscles, abnormal ribs, scar tissue in the postoperative period).

The level of narrowing of the vertebral artery correlates with the causes of the pathology.

If compression occurs before the entry into the bone canal, then this is due to spasm of the scalene muscle, increased stellate ganglion. It is more common with an abnormal location of the initial section of the artery. Here is the most vulnerable area for the deposition of atherosclerotic plaques (70% of cases).

Inside the bone canal from the transverse processes of the vertebrae, dangerous for the vessel can be:

• enlarged hook-shaped processes;
• subluxations in the vertebral joints, leading to pinching of one or both arteries;
• consequences of spondyloarthrosis, proliferation of articular surfaces;
• disc herniation (rare).

When exiting the canal, the arteries prevent:

• furrow too deep top edge atlanta, which forms an additional bone canal (Kimerli anomaly);
• pressing against the bodies of the vertebrae by the spasmodic lower oblique muscle of the head;
• atherosclerotic plaques (it has been established that the extracranial parts of the artery are more often affected by atherosclerosis than the internal ones);
• increased tortuosity and additional kinks are formed more often at the level of the first or second cervical vertebrae, usually combined with similar changes in the subclavian and.

The main cause of increased tortuosity, which causes non-straightness of the course of the vertebral arteries, is the loss of elastic properties of the vessel wall in age-related disorders in collagen metabolism, prolonged hypertension

Thrombotic changes in the vertebral arteries are found at autopsy in 9% of people who have had cerebrovascular diseases. As a rule, they are preceded by severe atherosclerosis. Without atherosclerotic changes, thrombosis is facilitated by the development of the “steal” syndrome with reverse vortex blood flows due to the subclavian artery and its other branches.

How is impaired patency of the vertebral arteries manifested?

Clinical signs of impaired blood flow in the vertebral arteries depend on such factors:

• state of the circle of Willis;
• development of a network of collaterals and anastomoses with the subclavian artery;
• the rate of increase in obstruction.

A combination of symptoms indicates damage to a specific part of the brain. The most common ischemia of the pool:

• posterior artery of the brain;
• zones of the trunk or cerebellum (in acute and chronic variants);
• nuclei and cranial nerves causing vestibular disorders.

The disease has a crisis course. Vertebral crises are manifested by a variety of symptoms. Most often stimulated by head movements. At the same time, damage to the brachial plexus and spinal cord is detected.

Syndrome of "cervical" migraine accompanies cervical osteochondrosis, spondylosis. Characterized by:

• typical pains in the back of the head and neck, radiating to the supraorbital region;
• fainting;
• dizziness;
• tinnitus.

Pain duration ranges from minutes to hours.

Vestibular crises are accompanied by:

• severe dizziness, a sense of rotation of objects;
• eye nystagmus;
• disturbed balance.

Atonic-adynamic syndrome appears with ischemia of the medulla oblongata:

• a sharp decrease in muscle tone;
• inability to stand on their own.

Visual disturbances due to impaired eye microcirculation:

• spots, dots, lines before the eyes;
• darkening;
• transient loss of visual fields;
• sensation of flashes in the eyes (photopsies), reduction visible objects(micropsy);
• optical illusions.

Less common:

• Syndrome of transient tonic convulsions in the arms and legs without loss of consciousness, while the extensor muscles are tensed and the limbs are extended. The symptom of "intermittent claudication" in the hands is observed in 65% of patients.
• Transient speech disorders, spasm of masticatory muscles.
• Sudden contraction of the diaphragm, which is manifested by paroxysmal cough, pupil dilation on the side of the lesion, increased salivation, tachycardia.

Outside of crises, the neurologist will notice in the patient some mild focal symptoms, paresis of some pairs of cranial nerves.

Characteristics of the main symptoms

Headaches are present in 73% of patients. They have a shooting, tightening, pulsating character.

Amplify:

• on palpation of the cervical vertebrae;
• after sleeping in an uncomfortable position;
• due to local cooling.

Dizziness often worries in the morning after sleep, accompanied by impaired hearing, vision, a sensation of noise in the head.

Such a sign as tinnitus, in most patients, is felt on both sides.

With one-sided noise, it indicates the side of the lesion

Characterized by an increase in the height of the audible noise at the onset and its decrease in the interictal period. Patients note a change during the day with osteochondrosis (increased at night).

Numbness is observed on the skin of the neck, around the mouth, on the hands.

Fainting is provoked by overextension of the head back. Usually they are preceded by other listed manifestations.

Nausea and vomiting are considered harbingers of a crisis.

The long course of the disease causes mental changes in patients, accompanied by depression.

What is the danger of violations?

Impaired patency of the vertebral arteries eventually causes ischemia of different parts of the brain. Vascular crises are variants of transient ischemic attacks. Lack of attention to symptoms wrong treatment soon contribute to the development of a "full-fledged" ischemic stroke with adverse consequences: paresis, paralysis, impaired speech, vision.

Missing important symptoms means dooming the patient to disability and his own helplessness. Recovery after a stroke is not for everyone and requires a lot of effort.

How to identify the pathology of the vertebral arteries?

By the presence of symptoms, the determination of its connection with neck movements, the doctor suspects the pathology of the vertebral arteries general practice or a therapist. In time to refer to a neurologist and for examination is a matter of experience.

Duplex scanning allows you to see the structure of the vessel, determine the nature of the stenosis, the degree of damage to the walls of the artery

Main methods:

• ultrasound dopplerography- an assessment is made of all anatomical characteristics of the vertebral arteries on both sides, the diameter along the length, the speed of the blood flow wave, which is important as a way to determine the reserve of cerebral circulation;
• magnetic resonance imaging of the brain and neck vessels will indicate the resulting foci with impaired blood supply, the formation of cysts, aneurysms;
• according to the radiograph of the cervical spine, one can judge the participation of pathological growths of bone tissue in the pinching of the vertebral arteries;
• Angiography of the vessels of the neck is performed by injecting a contrast agent into the subclavian artery. The technique is informative, but it is carried out only in specialized departments.

Methods of treatment

One of the simple methods of treatment is the constant wearing of the Shants collar. By the way, it is also used for diagnostics: if the patient feels improvement against the background of using the collar, this confirms the connection with the pathology of the vertebral arteries.

The value of exercise therapy and massage

Rare vascular crises make it possible to do without potent drugs in treatment. To do this, you need to master the exercises physiotherapy exercises and massage techniques.

Movements should be done carefully, at a slow pace:

• turning the head to the sides, first with a small amplitude, gradually increasing it;
• forehead pressure on the ball;
• head nods;
• shrug.

Massage is not available acute period. Its main task is to relieve tension in the neck muscles and reduce pressure on the arteries. It is not recommended to trust the procedure to an inexperienced person.

Medication treatment

Depending on the cause of the narrowing, the doctor chooses drugs:

• anti-inflammatory action (Nimesulide, Ketorol, Naizilat);
• to maintain vascular tone, you will need Troxerutin and a group of venotonics;
• thrombosis can be prevented with the help of Curantyl, Trental;
• with dizziness and vestibular disorders, Betaserk, Betahistine are indicated;
• neuroprotectors (Mexidol, Piracetam, Gliatillin) are needed to protect the brain from ischemia.

Physiotherapy techniques have the same goals as massage, they contribute to pain relief. Courses assigned:

• magnetotherapy,
• diadynamic currents,
• phonophoresis with hydrocortisone.

Acupuncture and traction can only be used in specialized centers.

Exercise therapy is especially indicated for sedentary work

When is surgery necessary?

The first operation to reconstruct the vertebral artery was performed in 1956, and in 1959, a blood clot was first removed from the subclavian artery with the capture of the bed of the vertebral vessel.

Indications for surgery are judged by the results conservative therapy. If the treatment is ineffective, and if established reason associated with compression of the artery by a tumor, a process of a vertebra, do without surgical intervention impossible.

Operate patients in neurosurgical departments. Produce removal bone formations, tumors, sympathetic nodes (to eliminate excessive spasm).

It is possible to eliminate abnormal tortuosity only if it is localized in segment I.

Crisis prevention

With an established diagnosis, the patient is able to prevent vascular crises. For this you need:

• do gymnastic exercises;
• wean yourself from sleeping on your stomach;
• take courses of physiotherapy and massage at least twice a year;
• purchase an orthopedic pillow to ensure an even position of the cervical spine during sleep;
• wear a Shants collar;
• get rid of the factors of narrowing of the arteries (smoking, drinking alcohol).

The stroke clinic is not necessarily caused by intracerebral vessels. Extracranial disorders should always be kept in mind when making a diagnosis and prescribing treatment. This strategy helps prevent life-threatening complications.

Asymmetry of blood flow in the vertebral arteries - enough unpleasant ailment. It appears due to improper blood supply to the human brain, as a result of damage to the main arteries.

It has another name - vertebral artery syndrome, as well as vertebrobasilar syndrome. This disease is quite common in Lately. Previously, it affected the elderly population, but now this syndrome is increasingly affecting people in their 20s and 30s.

The reasons for the appearance of such a disease may be the following:

• Due to the influence of some unfavorable factors, the patient begins to pinch the artery that supplies blood to the brain. In some cases, both arteries are affected.
• After clamping the artery, oxygen and nutrients cannot normally enter the patient's body.

If this unpleasant ailment is not treated, ischemic stroke and others may appear in the future. This is due to the fact that the state of the human brain is directly related to the work of all organs.In order to scientifically explain why such a syndrome arises, it is necessary to consider in more detail what is the structure of the blood supply to the brain as a whole. The most important current blood is coming from them to the head area (from 75 to 82%).

If at least one of them is injured, this can cause quite serious disorders, often leading to a rather unpleasant disease - ischemia.

As for the two remaining arteries, they are the left and the right. They carry the rest of the blood to the brain. Since there is not such a high percentage here, in comparison with any of the carotid arteries, it is believed that any malfunction in the work of such organs is not so dangerous for humans. But it is not so. In some cases, if the right or left artery is pinched, then a stroke can be completely avoided.

Useful video - Vertebral Artery Syndrome:

Although there may still be some problems. They relate to how the patient feels, and then to diseases associated with the organs of hearing, vision, etc. It is not uncommon for such an unpleasant ailment to lead to disability in the patient.

Symptoms of the disease

Hypertension, vestibular disorders, headache- signs of vertebral artery syndrome

Without proper diagnosis, it can be quite difficult to recognize the symptoms of blood flow asymmetry in the vertebral arteries. This is not due to the fact that such a disease does not manifest itself in any way. On the contrary, the signs of vertebrobasilar syndrome are very similar to other diseases.

It starts with osteochondrosis, very common among different groups population, and ends with diseases that the patient can hardly associate with. That is why, as soon as at least one of the symptoms listed below is detected, you should immediately contact a medical institution for carrying out.

Very often, patients with vertebrobasilar disease may develop a headache. It is manifested either by attacks that pass with the same frequency or have the same basis. Mostly pain concentrated in the occipital region. But besides this, they can also spread to the temporal region and even the forehead.Vertebrobasilar syndrome very often begins to increase over time. On the skin, in places where hair grows, discomfort increase with touching this area. All this can go together with a burning sensation.

Another symptom of the vertebrobasilar symptom is a strong crunch of the vertebrae in the neck with any turn of the head.

If the patient has this pathology, then first of all, doctors recommend that such patients change their lifestyle to a more active one. It is largely thanks to this method that most of those who have asymmetry of blood flow through the vertebral arteries can easily defeat such an unpleasant ailment.

Other signs:

• felt in the ears loud noise and ringing
• the patient periodically vomits
• heart hurts
• constant feeling of fatigue
• dizzy, up to a state similar to fainting
• the patient loses consciousness
• severe tension in the neck or pain in that area
• vision is impaired
• sore eyes and ears

Sometimes, in addition to this syndrome, VVD can develop, as well as an increase in pressure inside cranium. In addition, very often the arms or legs go numb, mainly the fingers on the limbs. Among other things, signs such as mild psychological deviations in the patient may appear.But it should be remembered that all these symptoms do not appear immediately, so some patients may delay the treatment of such an unpleasant ailment.

Causes of occurrence and risk groups

Causes and risk groups by this disease can be completely different:

• The most main reason such an ailment is the not quite uniform development of a pair of arteries, which leads to asymmetry of blood flow. This type of pathology cannot be cured. modern medicine. Often the patient lives with such an ailment until his death, without feeling the slightest inconvenience.
• Not too stable vertebrae in the cervical region can also be the cause of this syndrome. They gradually lead to the destruction of the disks in it and to their weakening. It can develop as a result of an injury in a patient (for example, after an accident) or gradually, due to lifestyle. In the second case, the reason for the appearance of blood flow asymmetry is a sedentary lifestyle, without sports, or ordinary physical activity.
• Another reason for the occurrence of such an ailment is associated with extravasal compression. And she, in turn, appears due to hernias and injuries. Also, such a pathology can develop into others.
• Injury received during childbirth is another factor that causes vertebrobasilar disease.
• Osteochondrosis is very common cause occurrence of vertebrobasilar symptoms.

Tortuous arteries of the spine can also be the beginning of the development of such a disease. This pathology is quite dangerous, and in many cases can lead to strokes. It is for this reason that patients who have been diagnosed with such a syndrome can almost instantly fall into the risk group. Such a category of patients should definitely monitor their health with particular scrupulousness. They especially recommend an active lifestyle.

If you have any of the pathologies listed above, you should start playing sports or at least exercising. In addition, it is necessary to undergo diagnostics once every few years to identify such a disease at an early stage.

Diagnostics

Ultrasound of neck vessels effective diagnostics pathology

During the initial examination of the patient, the specialist pays great attention to the absence or presence of such a syndrome. To do this, he looks at the occipital region, and in particular, checks the muscle tension in this place. Asks the patient if the skin on the head or cervical vertebrae is painful during pressure.

To date, the diagnosis of such a syndrome is carried out not only by visual inspection, but also with the help of Doppler ultrasound (USDG). Thanks to this method, the arteries are also examined, their condition is revealed, as well as the disorders present in the patient's body. Among other things, during the correct diagnosis, in some cases, the specialist uses x-rays.

If during such a procedure at least minimal exacerbations are detected, then the sick person is sent to.

In some cases, after the results of the examination, the patient may be urgently hospitalized.

Pathology treatment method

Treatment of blood flow asymmetry should occur strictly only under the supervision of a specialist, even if it occurs at the patient's home.

Therapy in all cases should have an integrated approach. It includes the methods listed below. But the doctor, at his discretion, can add or change something:

• course of vascular therapy
• appointment of therapeutic exercises
• drugs that improve blood flow
• medicines that improve general state patient
• well manual therapy(preferably conducted by healthcare professionals)
• carrying out autogravity

In addition to the methods listed above, other non-drug methods are also practiced. But every patient with such an unpleasant disease should remember that self-medication is fraught with the appearance of unpleasant ones. That is why treatment should be prescribed by a specialist on an individual basis. Everything will depend on the cause of the disease and its stage.

If the patient has this pathology, then first of all, doctors recommend that such patients change their lifestyle to a more active one.

It is largely thanks to this method that most of those who have asymmetry of blood flow through the vertebral arteries can easily defeat such an unpleasant ailment. But do not forget that such therapy must be used in combination with other methods. That is when the treatment will have the desired effect.

It is possible to increase the blood flow rate by increasing the number of heartbeats per unit time so that more blood is distilled through the filter element (2) per unit time, and the filtration rate will increase. The body does just that. It increases the number of heart contractions, Claude Bernard's law is fulfilled. But let's see where this leads us. We know that the capacity of the arterial part of the vascular bed in a grown person (sector 5 in the BCH) is constant. We know that arteries, unlike veins, are thicker and have a muscular wall that can contract, reducing the capacity of the arteries. We know that blood is a liquid, and liquid is incompressible. In this case, we have the following discrepancy: the heart per unit time pumps into the arterial

the capacity of the blood is greater than the capacity itself. And this leads to an increase in blood pressure in the arterial container. And we got what in clinical parlance is called type 1 hypertension, or hyperkinetic hypertension, or ejection hypertension. This increased workload on the heart leads to thickening of the heart muscle and is called working myocardial hypertrophy. Increased pressure in the arteries (arterioles) can open the shunts (5) and lead to partial discharge of blood into the venous capacity of the vascular bed. Veins do not have a muscular wall and are more elastic than arteries. Therefore, the discrepancy between the venous capacity and the volume of blood in it will lead to the expansion of the venous capacity. Expansion of venous capacity will give what is called in medicine varicose veins.

So, biofilters fulfilled Claude Bernard's law of life at the cost of hypertension of the first type, myocardial hypertrophy, varicose veins. The system continues to live, and the water continues to leave the body as a fact and as a condition of the problem.

The filtering area of ​​cell membranes continues to shrink. And the blockade of filtration increases again, and again toxins accumulate in the blood and deviate blood homeostasis from the law of Claude Bernard. And again, in order to live, you must fulfill this law, which means removing slags. If we again follow the path of increasing the work of the heart, then a breakdown of the central neuro-reflex regulation of the work of the heart may occur. For some people, this happens, and we get what is called in the clinic of internal diseases cardioneurosis. But more often the body follows a different path.

From physics, we know that the narrower the vessel, the higher the blood flow rate, which means that the narrowing of the vessels (arteries) will provide us with an increase in the rate of blood filtration per unit time and the fulfillment of Claude Bernard's law. The body does just that. With the help of nervous regulation, it reduces the diameter of the arteries (arterioles) and thus achieves an increase in blood flow and filtration rate. But this leads to the following. Again, there is a discrepancy between the capacity of the arteries and the volume of blood. The blood volume becomes larger again relative to the arterial capacity. And attempts to drive more into less again lead to an increase in blood pressure. Arises in the language of medicine hypertension of the second type, or volume hypertension, or vasoconstrictor hypertension.(These are all different names for the same thing.) Since the required filtration rate is provided by vasoconstriction, the number of heartbeats drops. But since the resistance to blood flow both from the side of the vessels and from the side of the more blocked filter element is even higher than before, the heart will increase myocardial hypertrophy up to the expansion of the ᴇᴦο chambers, which is called