12.04.2019

Blood circulation is collateral. Compensatory processes for local circulatory disorders

Table of contents of the topic “Patterns of distribution of arteries.”:

Collateral circulation is an important functional adaptation of the body associated with the great plasticity of blood vessels and ensuring uninterrupted blood supply to organs and tissues. A deep study of it, which has important practical significance, is associated with the name of V. N. Tonkov and his school

Collateral circulation means lateral, roundabout flow of blood through the lateral vessels. It takes place in physiological conditions with temporary difficulties in blood flow (for example, with compression of blood vessels in places of movement, in joints). It can also occur in pathological conditions for blockages, wounds, ligation of blood vessels during operations, etc.

Under physiological conditions, roundabout blood flow occurs through lateral anastomoses running parallel to the main ones. These lateral vessels are called collaterals (for example, a. collateralis ulnaris, etc.), hence the name of the blood flow “roundabout”, or collateral circulation.

When there is difficulty in blood flow through the main vessels, caused by their blockage, damage or ligation during operations, blood rushes through the anastomoses into the nearest lateral vessels, which expand and become tortuous, vascular wall they are rebuilt due to changes in the muscular layer and elastic frame and they are gradually transformed into collaterals of a different structure than normal.

Thus, collaterals exist in normal conditions, and can develop again in the presence of anastomoses. Consequently, in case of a disorder of normal blood circulation caused by an obstacle to the blood flow in a given vessel, the existing bypass blood paths - collaterals - are first turned on, and then new ones develop. As a result, impaired blood circulation is restored. The nervous system plays an important role in this process.

From the above it follows that it is necessary to clearly define difference between anastomoses and collaterals.

Anastomosis (from the Greek anastomos - I supply the mouth)- anastomosis, every third vessel that connects two others; This is an anatomical concept.

Collateral (from Latin collateralis - lateral)- a lateral vessel that carries out a roundabout flow of blood; This concept is anatomical and physiological.

There are two types of collaterals. Some exist normally and have the structure of a normal vessel, like an anastomosis. Others develop again from anastomoses and acquire a special structure.

To understand collateral circulation it is necessary to know those anastomoses that connect the systems of various vessels, through which collateral blood flow is established in the event of vascular injuries, ligations during operations and blockages (thrombosis and embolism).

Anastomoses between branches of major arterial highways, supplying the main parts of the body (aorta, carotid arteries, subclavian, iliac, etc.) and representing, as it were, separate systems vessels are called intersystemic. Anastomoses between the branches of one large arterial line, limited to the limits of its branching, are called intrasystemic. These anastomoses have already been noted in the course of the presentation of the arteries.

There are anastomoses between the thinnest intraorgan arteries and veins - arteriovenous anastomoses. Through them, blood flows bypassing the microcirculatory bed when it is overfilled and, thus, forms a collateral path that directly connects the arteries and veins, bypassing the capillaries.

In addition, thin arteries and veins that accompany the great vessels in the collateral circulation take part in neurovascular bundles and components of the so-called perivascular and perivascular arterial and venous beds.

Anastomoses, in addition to their practical significance, they are an expression of the unity of the arterial system, which, for ease of study, we artificially divide into separate parts.

With ischemia, complete or partial restoration of blood supply to the affected tissue often occurs (even if the obstruction in the arterial bed remains). The degree of compensation depends on the anatomical and physiological factors blood supply to the corresponding organ.

To anatomical factors include features of arterial branching and anastomoses. There are:

1. Organs and tissues with well-developed arterial anastomoses (when the sum of their lumen is close in size to that of the blocked artery) - this is the skin, mesentery. In these cases, blockage of the arteries is not accompanied by any disturbance of blood circulation in the periphery, since the amount of blood flowing through the collateral vessels is sufficient from the very beginning to maintain normal blood supply to the tissue.

2. Organs and tissues whose arteries have few (or no) anastomoses, and therefore collateral blood flow into them is possible only through a continuous capillary network. Such organs and tissues include the kidneys, heart, spleen, and brain tissue. If an obstruction occurs in the arteries of these organs, severe ischemia occurs in them, and as a result, a heart attack.

3. Organs and tissues with insufficient collaterals. They are very numerous - these are the lungs, liver, and intestinal wall. The lumen of the collateral arteries in them is usually more or less insufficient to ensure collateral blood flow.

Physiological factor promoting collateral blood flow is the active dilatation of the arteries of the organ. As soon as a deficiency of blood supply occurs in the tissue due to blockage or narrowing of the lumen of the adductor arterial trunk, a physiological regulatory mechanism begins to work, causing an increase in blood flow through the preserved arterial pathways. This mechanism causes vasodilation, since products of impaired metabolism accumulate in the tissue, which have a direct effect on the walls of the arteries, and also excite sensitive nerve endings, resulting in a reflex dilatation of the arteries. At the same time, all collateral pathways of blood flow into the area with circulatory deficiency expand, and the speed of blood flow in them increases, facilitating blood supply to the tissue experiencing ischemia.

This compensation mechanism functions differently in different people and even in the same organism under different conditions. In people weakened by a long-term illness, the mechanisms of compensation for ischemia may not function sufficiently. For effective collateral blood flow, the condition of the artery walls is also of great importance: collateral blood flow paths that are sclerotic and have lost elasticity are less capable of expansion, and this limits the possibility of a complete restoration of blood circulation.

If the blood flow in the collateral arterial pathways supplying blood to the ischemic area remains increased for a relatively long time, then the walls of these vessels are gradually rebuilt in such a way that they turn into arteries of a larger caliber. Such arteries can completely replace a previously blocked arterial trunk, normalizing blood supply to tissues.

There are three degrees of severity of collaterals:

Absolute sufficiency of collaterals - the sum of the lumen of the collaterals is either equal to the lumen of the closed artery or exceeds it.

Relative sufficiency (insufficiency) of collaterals - the sum of the lumen, collaterals less than the lumen of a closed artery;

Absolute insufficiency of collaterals - collaterals are poorly expressed and even with full disclosure they are not able to compensate for impaired blood circulation to any significant extent.

Shunting. Shunting is the creation of an additional path bypassing the affected area of a vessel using a system of shunts. An effective method for treating myocardial ischemia is coronary artery bypass grafting. The affected area of the artery is bypassed using shunts - an artery or vein taken from another part of the body, which is fixed to the aorta and below the affected area of the coronary artery, thus restoring blood supply to the ischemic area of the myocardium. In case of hydrocephalus, surgical cerebrospinal fluid shunting of the brain is performed - as a result, the physiological flow of cerebrospinal fluid is restored and the symptoms of increased cerebrospinal fluid pressure disappear (excess cerebrospinal fluid is removed from the ventricles of the brain into the body cavity through a system of valves and tubes).

Insufficiency of lymph circulation during blockade of the lymphatic bed can be compensated by a certain functional reserve, which allows to increase the volume and speed of drainage to a certain extent (lymphatic-lymphatic shunts, lymph-venous shunts).

Stasis

Stasis- this is a stop of blood and/or lymph flow in capillaries, small arteries and venules.

Types of stasis:

1. Primary (true) stasis. It begins with the activation of FEC and their release of proaggregants and procoagulants. FEC aggregate, agglutinate and attach to the wall of microvessels. Blood flow slows and stops.

2. Ischemic stasis develops as an outcome of severe ischemia, with a decrease in the influx of arterial blood, a slowdown in the speed of its flow, and its turbulent nature. Blood cell aggregation and adhesion occurs.

3. Congestive (venous-congestive) variantstasis is the result of a slowdown in the outflow of venous blood, its thickening, changes in physicochemical properties, and damage to blood cells. Subsequently, the blood cells agglutinate, adhere to each other and to the wall of microvessels, slowing down and stopping the outflow of venous blood.

Causes:

Ischemia and venous hyperemia. When blood flow slows down, the formation or activation of substances that cause the adhesion of FEC, the formation of aggregates and blood clots.

Proaggregants (thromboxane A2, Pg F, Pg E, adenosine diphosphate, catecholamines, antibodies to FEC) are factors that cause aggregation and agglutination of FEC with their lysis and release of biologically active substances.

Rice. 8 – The mechanism of development of stasis under the influence of proaggregants.

Collateral Circulation

The role and types of collateral circulation

The term collateral circulation implies the flow of blood through the lateral branches into the peripheral parts of the limbs after blocking the lumen of the main (main) trunk.

Collateral blood flow is an important functional mechanism of the body, due to the flexibility of blood vessels and is responsible for uninterrupted blood supply to tissues and organs, helping to survive myocardial infarction.

The role of collateral circulation

Essentially, collateral circulation is a roundabout lateral blood flow that occurs through the lateral vessels. Under physiological conditions, it occurs when normal blood flow is obstructed, or in pathological conditions - wounds, blockage, ligation of blood vessels during surgery.

The largest ones, taking on the role of a switched off artery immediately after blockage, are called anatomical or preceding collaterals.

Groups and types

Depending on the localization of intervascular anastomoses, previous collaterals are divided into the following groups:

Intrasystemic - short paths of roundabout circulation, that is, collaterals that connect the vessels of the large arteries.
Intersystem - circuitous or long paths that connect basins different vessels together.

Collateral circulation is divided into types:

Intraorgan connections - intervascular connections inside separate body, between the vessels of the muscles and the walls of the hollow organs.
Extraorgan connections are connections between the branches of the arteries that supply a particular organ or part of the body, as well as between large veins.

The strength of collateral blood supply is influenced by the following factors: the angle of departure from the main trunk; diameter of arterial branches; functional state of blood vessels; anatomical features of the lateral anterior branch; the number of lateral branches and the type of their branching. An important point for volumetric blood flow is the state in which the collaterals are: relaxed or spasmodic. The functional potential of collaterals is determined by regional peripheral resistance and general regional hemodynamics.

Anatomical development of collaterals

Collaterals can exist both under normal conditions and develop again during the formation of anastomoses. Thus, a disruption of the normal blood supply caused by some obstruction in the path of blood flow in a vessel involves already existing blood bypasses, and after that new collaterals begin to develop. This leads to the fact that the blood successfully bypasses the areas in which the patency of the vessels is impaired and the impaired blood circulation is restored.

Collaterals can be divided into the following groups:

sufficiently developed, characterized by wide development, the diameter of their vessels is the same as the diameter of the main artery. Even complete closure of the main artery has little effect on the blood circulation of such an area, since anastomoses fully replace the decrease in blood flow;
insufficiently developed ones are located in organs where intraorgan arteries interact little with each other. They are usually called ring ones. The diameter of their vessels is much smaller than the diameter of the main artery.
relatively developed ones partially compensate for impaired blood circulation in the ischemic area.

Diagnostics

To diagnose collateral circulation, you first need to take into account the rate of metabolic processes in the extremities. Knowing this indicator and competently influencing it using physical, pharmacological and surgical methods, you can maintain the viability of an organ or limb and stimulate the development of newly formed blood flow pathways. To do this, it is necessary to reduce the tissue consumption of oxygen and nutrients supplied by the blood, or to activate collateral circulation.

What is collateral circulation

What is collateral circulation? Why do many doctors and professors focus on the important practical significance of this type of blood flow? Blockage of the veins can lead to a complete blockage of blood movement through the vessels, so the body begins to actively look for the possibility of supplying liquid tissue through lateral routes. This process is called collateral circulation.

The physiological characteristics of the body make it possible to supply blood through vessels that are located parallel to the main ones. Such systems have a medical name - collaterals, which is translated from Greek as “circuitous”. This function allows you to pathological changes, injuries, surgical interventions, ensure uninterrupted blood supply to all organs and tissues.

Types of collateral circulation

In the human body, collateral circulation can have 3 types:

Absolute or sufficient. In this case, the sum of collaterals that will slowly open is equal to or close to the main vessels. Such lateral vessels perfectly replace pathologically altered ones. Absolute collateral circulation is well developed in the intestines, lungs and all muscle groups.
Relative, or insufficient. Such collaterals are located in the skin, stomach and intestines, bladder. They open more slowly than the lumen of a pathologically altered vessel.
Insufficient. Such collaterals are unable to completely replace the main vessel and allow blood to fully function in the body. Insufficient collaterals are located in the brain and heart, spleen and kidneys.

As medical practice shows, the development of collateral circulation depends on several factors:

individual structural features vascular system;
the time during which the blockage of the main veins occurred;
age of the patient.

It is worth understanding that collateral circulation develops better and replaces the main veins at a young age.

How is the replacement of the main vessel with a collateral one assessed?

If the patient has been diagnosed with serious changes in the main arteries and veins of the limb, the doctor assesses the adequacy of the development of collateral circulation.

To give a correct and accurate assessment, the specialist considers:

metabolic processes and their intensity in the limbs;
treatment option (surgery, medications, and exercises);
the possibility of full development of new pathways for the full functioning of all organs and systems.

The location of the affected vessel is also important. It will be better to produce blood flow at an acute angle of departure of the branches of the circulatory system. If you choose an obtuse angle, the hemodynamics of the vessels will be difficult.

Numerous medical observations showed that for the full opening of collaterals, it is necessary to block the reflex spasm in the nerve endings. Such a process may occur because when a ligature is applied to an artery, irritation of the semantic nerve fibers occurs. Spasms can block the full opening of the collateral, so such patients undergo novocaine blockade sympathetic nodes.

Acute coronary syndrome - acute IHD phase. Atherosclerosis, which underlies ischemic heart disease, is not a linearly progressive, stable process. Atherosclerosis of the coronary arteries is characterized by alternating phases of stable progression and exacerbation of the disease.

IHD is a discrepancy between coronary blood flow and the metabolic needs of the myocardium, i.e. volume of myocardial oxygen consumption (PMO2).

In some cases clinical picture Chronic stable ischemic heart disease is caused by symptoms and signs of LV dysfunction. This condition is defined as ischemic cardiomyopathy. Ischemic cardiomyopathy is the most common form of heart failure in developed countries, reaching a level of 2/3 to 3/4 of cases.

Collateral coronary circulation

Networks of small branch anastomoses internally connect the main coronary arteries (CA) and serve as precursors of collateral circulation, which ensures myocardial perfusion despite severe proximal narrowing of the coronary arteries (CA) of atherosclerotic origin.

Collateral ducts may be invisible in patients with normal and mildly damaged coronary arteries (CA) due to their small size (< 200 мкм) калибра, но по мере прогрессирования КБС и увеличения ее тяжести (>90% stenosis) in the anastomotic ducts, ▲P occurs in relation to the distal hypoperfused areas.

Transstenotic ▲P promotes blood flow through the anastomotic vessels, which progressively dilate and eventually become visible as collateral vessels.

Visible collateral ducts arise from either the contralateral coronary artery or the lateral coronary artery located on the same side, through intracoronary collateral ducts or through bridging canals, which have a serpentine arrangement from the proximal coronary artery to the distal coronary artery duct.

These collaterals can provide up to 50% of the anterograde coronary blood flow during chronic total occlusion and may participate in the creation of “protective” areas of myocardial perfusion in which myocardial ischemia does not develop during times of increased oxygen demand. Collateral involvement can occur rapidly in patients who develop OHM ST as a result of unexpected thrombotic occlusion.

Other factors that determine the development of collaterals include the condition of the arteries supplying the collaterals and the size and vascular resistance of the segment distal to the stenosis.

Collateral flow quality can be graded using Rentrop criteria, including grade 0 (no filling), grade 1 (small side branches filled), grade 2 (partial epicardial filling of the occluded coronary artery), or grade 3 (complete epicardial filling of the occluded coronary artery).

(A) Kygel's branch starts from the proximal part of the right coronary artery and continues to the distal portion of the posterior descending branch of the right coronary artery (arrow).

(B) Bridging collaterals (arrow) connecting the proximal and distal parts of the right coronary artery.

(B) “Microduct” in the middle left anterior descending artery (arrow).

(D) The Viessen collateral runs from the proximal right coronary artery to the left anterior descending artery (arrow).

Collateral coronary circulation

So what does the course of IHD depend on?

The main reason for the development and progression of coronary artery disease is damage to the coronary arteries of the heart by atherosclerosis. A decrease in the lumen of the coronary artery by 50% can already clinically manifest itself as angina attacks. A decrease in the lumen by 75 percent or more gives classic symptoms - the appearance of angina attacks during or after physical and emotional stress and a fairly high probability of developing myocardial infarction.

However, in human body, as a biological object of a higher order, there is a huge reserve potential that is activated for any pathological process. With stenotic atherosclerosis of the coronary arteries, the main compensation mechanism is collateral circulation, which takes over the function of blood supply to the heart muscle in the affected artery basin.

What is collateral circulation?

Scientific assumption about the compensatory capabilities of the vascular system during coronary insufficiency has a history of almost two centuries. The first information about the presence of collaterals was obtained by A. Scarpa in 1813, but only the dissertation work of the Russian surgeon and researcher N.I. Pirogov laid the foundation for the doctrine of collateral circulation. However, a whole era has passed from the numerous postmortem studies to the modern understanding of the mechanism of development of collateral circulatory pathways.

The coronary bed, which ensures the viability of the myocardium, consists of the left and right coronary arteries. The basin of the left coronary artery is represented by the anterior interventricular, circumflex and diagonal arteries. When it comes to coronary atherosclerosis, in most cases the stenotic process develops here - in one or several arteries.

In addition to the large main arteries, the heart has vascular formations- coronary anastomoses that penetrate all layers of the myocardium and connect the arteries to each other. The diameter of the coronary anastomoses is small, from 40 to 1000 microns. IN healthy heart they are in a “dormant” state, are underdeveloped vessels and have little functional significance. But it is not difficult to imagine what will happen to these vessels when the main blood flow encounters an obstacle on its usual route. In childhood, everyone probably loved to watch a stream after rain: as soon as you block it with a stone or a piece of wood, the water immediately begins to look for new passages, breaks through them where it “feels” the slightest slope, bypasses the obstacle and returns to its native channel again. We can say: the dam forced the stream to look for its collaterals.

Intrawall anastomoses: the Tebesian vessels and sinusoidal spaces are of considerable importance in maintaining collateral circulation. They are located in the myocardium and open into the cavity of the heart. The role of the Temesian vessels and sinusoidal spaces as sources of collateral circulation has recently been intensively studied in connection with the introduction into clinical practice of transmyocardial laser revascularization in patients with multiple coronary lesions.

There are extracardiac anastomoses - anatomical connections of the arteries of the heart with the arteries of the pericardium, mediastinum, diaphragm, and bronchial arteries. Each person has their own unique structure, which explains the individual level of myocardial protection during various influences on the cardiovascular system.

Congenital failure of coronary anastomoses can cause myocardial ischemia without visible changes in the main coronary arteries. In addition to the anastomoses present in the heart from birth, there are collateral connections formed during the onset and progression of coronary atherosclerosis. It is these newly formed arterial vessels that represent true collaterals. The fate of a patient with coronary heart disease, the course and outcome of coronary heart disease often depend on the speed of their formation and functional viability.

Acute occlusion of the coronary arteries (cessation of blood flow due to thrombosis, complete stenosis or spasm) is accompanied by the appearance of collateral circulatory pathways in 80% of cases. With a slowly developing process of stenosis, roundabout blood flow paths are detected in 100% of cases. But for the prognosis of the disease, the question of how effective these workarounds are is very important.

Hemodynamically significant are the collaterals that arise from intact coronary arteries, and in the presence of occlusion, those that develop above the stenotic area. However, in practice, the formation of collaterals above the stenotic area occurs only in 20-30% of patients with coronary artery disease. In other cases, roundabout blood flow paths are formed at the level of the distal (terminal) branches of the coronary arteries. Thus, in most patients with coronary artery disease, the ability of the myocardium to resist atherosclerotic damage to the coronary arteries and compensate for physical and emotional stress is determined by the adequacy of the distal blood supply. The collaterals that develop during the process of progression are sometimes so effective that a person endures quite large loads without suspecting the presence of damage to the coronary arteries. This explains those cases when myocardial infarction develops in a person without previous clinical symptoms angina pectoris.

This brief and perhaps not entirely easy-to-understand overview of the anatomical and functional features of the blood supply to the heart muscle - the main “pumping” organ that ensures the life of the body - is not presented to the attention of readers by chance. In order to actively resist IHD, the “number one” disease in the sad mortality statistics, a certain medical awareness and the absolute determination of each person for a long fight against such an insidious and strong enemy as atherosclerosis are necessary. Previous issues of the magazine presented in detail necessary methods examination of a potential patient with coronary artery disease. However, it seems appropriate to recall that males over 40 years of age and females aged 45-50 years should show their interest and persistence in conducting a cardiac examination.

The algorithm is simple, accessible if desired, and includes the following diagnostic methods:

study of lipid metabolism (determination of risk factors such as hypercholesterolemia and hypertriglyceridemia - they were discussed in ZiU No. 11 / 2000);
study of microcirculation, which allows non-invasive method to identify early signs damage to the cardiovascular system and indirectly assess the condition of collaterals. (Read about this in “ZiU” No. 12/2000.)
determination of coronary reserve and identification of signs of myocardial ischemia on physical activity. (Functional examination methods must necessarily include a bicycle ergometer test under ECG control)
echocardiographic examination (assessment of intracardiac hemodynamics, the presence of atherosclerotic lesions of the aorta and myocardium).

The results of such a diagnostic complex will make it possible to identify IHD with a high degree of reliability and outline tactics for further examination and timely treatment. If you already have, perhaps, not entirely “intelligible” symptoms in the form of pain, discomfort or discomfort localized behind the sternum and radiating to the neck, lower jaw, in the left hand, which can be associated with physical and emotional stress; If your immediate family members suffer from coronary artery disease or hereditary hypercholesterolemia, a cardiological examination to the specified extent should be carried out at any age.

Of course, the most reliable method for identifying coronary lesions is coronary angiography. It allows you to determine the degree and extent of atherosclerotic artery damage, assess the state of collateral circulation and, most importantly, outline the optimal treatment tactics. Indications for this diagnostic procedure determined by a cardiologist if there are signs of coronary artery disease. This examination is inaccessible to Belarusian residents and is carried out only in a few specialized centers Minsk and Gomel. To some extent, this explains the late performance of coronary angiography, and therefore, in our country, patients with coronary artery disease with a “severe” class of angina pectoris, often with a history of myocardial infarction, are usually referred for surgical revascularization of the myocardium, while in countries Western Europe and the USA, coronary angiography is performed after the first “coronary attack” documented during bicycle ergometry. However, we have the opportunity to conduct coronary angiography in our country and, when indicated, it should be performed in a timely manner.

The arsenal of therapeutic effects and medical technologies in modern Belarusian cardiology is sufficient to provide adequate assistance to patients with coronary artery disease. This is classical cardiac surgery - aortocortical bypass surgery both under conditions of artificial circulation and on a “working” heart. This is minimally invasive cardiac surgery - balloon dilatation (expansion) of the affected area of the coronary artery with the installation of a special device - a stent, to increase the effectiveness of the procedure. This is transmyocardial laser revascularization of the myocardium, which was mentioned above. This drug regimens treatments using pentoxifylline (trental, agapurine) and non-drug technologies, such as selective plasmapheresis and low-intensity infrared laser therapy. They are the technologies of choice for patients who, for a number of reasons, cannot undergo surgical correction of atherosclerotic coronary lesions.

Collateral circulation;

Ligation of arteries throughout can be used not only as a way to stop bleeding from a damaged vessel, but also as a method of preventing it before performing some complex operations. To properly expose the artery for the purpose of ligation, it is necessary to perform operational access, which requires knowledge of the projection lines of the arteries. It should be especially emphasized that to draw the projection line of the artery, it is preferable to use the most easily identifiable and non-displaceable bony protrusions as a guide. Using soft tissue contours can lead to an error, since with edema, the development of a hematoma, or an aneurysm, the shape of the limb and the position of the muscles may change and the projection line will be incorrect. To expose the artery, an incision is made strictly along the projection line, cutting the tissue layer by layer. This type of access is called direct access. Its use allows you to approach the artery by the shortest route, reducing surgical trauma and operating time. However, in some cases, the use of direct access can lead to complications. To avoid complications, the incision to expose the arteries is made slightly away from the projection line. This access is called roundabout. The use of a roundabout approach complicates the operation, but at the same time avoids possible complications. The surgical method of stopping bleeding by ligating the artery along its length eliminates the isolation of the artery from the sheath of the neurovascular bundle and its ligation. To avoid damage to the elements of the neurovascular bundle, novocaine is first injected into its vagina for the purpose of “hydraulic preparation”, and the vagina is opened using a grooved probe. Before applying ligatures, the artery is carefully isolated from the surrounding connective tissue.

However, ligation of large main arteries not only stops bleeding, but also sharply reduces the flow of blood to the peripheral parts of the limb; sometimes the viability and function of the peripheral part of the limb is not significantly impaired, but more often necrosis (gangrene) of the distal part of the limb develops due to ischemia. In this case, the frequency of gangrene development depends on the level of arterial ligation and anatomical conditions, the development of collateral circulation.

The term collateral circulation refers to the flow of blood into the peripheral parts of the limb through the lateral branches and their anastomoses after closing the lumen of the main (main) trunk. The largest ones, which take on the function of a disabled artery immediately after ligation or blockage, are classified as so-called anatomical or pre-existing collaterals. Based on the localization of intervascular anastomoses, pre-existing collaterals can be divided into several groups: collaterals that connect the vessels of a large artery to each other are called intrasystemic, or short circuits of the roundabout circulation. Collaterals that connect the basins of different vessels with each other (the external and internal carotid arteries, the brachial artery with the arteries of the forearm, the femoral artery with the arteries of the leg) are classified as intersystem, or long, roundabout pathways. Intraorgan connections include connections between vessels within an organ (between the arteries of adjacent lobes of the liver). Extraorgan (between the branches of the own hepatic artery at the porta hepatis, including with the arteries of the stomach). Anatomical pre-existing collaterals after ligation (or blockage by a thrombus) of the main arterial trunk take on the function of conducting blood to the peripheral parts of the limb (region, organ). At the same time, depending on the anatomical development and functional sufficiency of the collaterals, three possibilities are created for restoring blood circulation: the anastomoses are wide enough to fully ensure blood supply to the tissues, despite the shutdown main artery; anastomoses are poorly developed, the roundabout circulation does not provide nutrition to the peripheral parts, ischemia occurs, and then necrosis; There are anastomoses, but the volume of blood flowing through them to the periphery is small for a complete blood supply, and therefore the newly formed collaterals are of particular importance. The intensity of collateral circulation depends on a number of factors: on the anatomical features of the pre-existing lateral branches, the diameter of the arterial branches, the angle of their departure from the main trunk, the number of lateral branches and the type of branching, as well as on the functional state of the vessels (the tone of their walls). For volumetric blood flow, it is very important whether the collaterals are in spasm or, conversely, in a relaxed state. It is the functional capabilities of the collaterals that determine regional hemodynamics in general and the value of regional peripheral resistance in particular.

To assess the sufficiency of collateral circulation, it is necessary to keep in mind the intensity of metabolic processes in the limb. Taking into account these factors and influencing them using surgical, pharmacological and physical methods, it is possible to maintain the viability of a limb or any organ in case of functional insufficiency of pre-existing collaterals and to promote the development of newly formed blood flow pathways. This can be achieved either by activating collateral circulation or by reducing tissue consumption of nutrients and oxygen supplied by the blood. First of all, the anatomical features of pre-existing collaterals must be taken into account when choosing the location of the ligature. It is necessary to spare the existing large lateral branches as much as possible and apply the ligature as low as possible below the level of their departure from the main trunk. The angle of departure of the lateral branches from the main trunk has a certain significance for collateral blood flow. The best conditions for blood flow are created with an acute angle of origin of the lateral branches, while an obtuse angle of origin of the lateral vessels complicates hemodynamics due to an increase in hemodynamic resistance. When considering the anatomical features of pre-existing collaterals, it is necessary to take into account the varying degrees of severity of anastomoses and the conditions for the development of newly formed blood flow pathways. Naturally, in those areas where there are many muscles rich in blood vessels, there are the most favorable conditions for collateral blood flow and new formation of collaterals. It must be taken into account that when a ligature is applied to an artery, sympathetic nerve fibers, which are vasoconstrictors, are irritated, and a reflex spasm of the collaterals occurs, and the arteriolar part of the vascular bed is switched off from the blood flow. Sympathetic nerve fibers pass in the outer lining of the arteries. To eliminate the reflex spasm of the collaterals and maximize the opening of the arterioles, one of the methods is to intersect the arterial wall along with the sympathetic nerve fibers between two ligatures. Periarterial sympathectomy is also recommended. A similar effect can be achieved by introducing novocaine into the periarterial tissue or novocaine blockade of the sympathetic nodes.

In addition, when an artery is crossed, due to the divergence of its ends, the straight and obtuse angles of origin of the lateral branches change to an acute angle that is more favorable for blood flow, which reduces hemodynamic resistance and improves collateral circulation.

Collateral circulation

Collateral circulation is an important functional adaptation of the body, associated with the great plasticity of blood vessels and ensuring uninterrupted blood supply to organs and tissues. Its in-depth study, which has important practical significance, is associated with the name of V.N. Tonkov and his school.

Collateral circulation refers to the lateral roundabout flow of blood through the lateral vessels. It occurs under physiological conditions during temporary difficulties in blood flow (for example, when blood vessels are compressed in places of movement, in joints). It can also occur in pathological conditions - during blockage, wounds, ligation of blood vessels during operations, etc.

When there is difficulty in blood flow through the main vessels, caused by their blockage, damage or ligation during operations, blood rushes through anastomoses into the nearest lateral vessels, which expand and become tortuous, the vascular wall is rebuilt due to changes in the muscular layer and elastic frame, and they are gradually transformed into collaterals different structure than normal.

Thus, collaterals exist under normal conditions, and can develop again in the presence of anastomoses. Consequently, in the event of a disorder of normal blood circulation caused by an obstacle to the blood flow in a given vessel, the existing bypass blood pathways and collaterals are first activated, and then new ones develop. As a result, impaired blood circulation is restored. The nervous system plays an important role in this process.

From the above it follows the need to clearly define the difference between anastomoses and collaterals.

Anastomosis (anastomoo, Greek - I supply the mouth) - an anastomosis is any third vessel that connects two others - an anatomical concept.

Collateralis (collateralis, lat. - lateral) is a lateral vessel that carries out a roundabout flow of blood; the concept is anatomical and physiological.

There are two types of collaterals. Some exist normally and have the structure of a normal vessel, like an anastomosis. Others develop again from anastomoses and acquire a special structure.

To understand collateral circulation, it is necessary to know those anastomoses that connect systems of various vessels through which collateral blood flow is established in the event of vascular injuries, ligation during operations and blockages (thrombosis and embolism).

Anastomoses between the branches of large arterial highways supplying the main parts of the body (aorta, carotid arteries, subclavian, iliac, etc.) and representing separate vascular systems are called intersystemic. Anastomoses between the branches of one large arterial line, limited to the limits of its branching, are called intrasystemic.

These anastomoses have already been noted in the course of the presentation of the arteries.

There are anastomoses between the thinnest intraorgan arteries and veins - arteriovenous anastomoses. Through them, blood flows bypassing the microcirculatory bed when it is overfilled and, thus, forms a collateral path that directly connects the arteries and veins, bypassing the capillaries.

In addition, thin arteries and veins take part in the collateral circulation, accompanying the main vessels in the neurovascular bundles and constituting the so-called perivascular and perivascular arterial and venous beds.

Anastomoses, in addition to their practical significance, are an expression of the unity of the arterial system, which, for ease of study, we artificially divide into separate parts.

Collateral circulation

The term collateral circulation refers to

blood flow to the peripheral parts of the limb through the bo-

kovy branches and their anastomoses after closing the lumen of the main

nogo (main) trunk. The largest, receiving

assumes the function of the disconnected artery immediately after ligation

or blockages are classified as so-called anatomical or

pre-existing collaterals. Pre-existing collates

The localization of intervascular anastomoses can be divided into

pour into several groups: collaterals connecting between the

fight the vessels of the basin of any large artery, called

intrasystemic, or short routes of the roundabout blood circulation

scheniya. Collaterals connecting different basins to each other

nal vessels (external and internal carotid arteries, brachial

arteries with the arteries of the forearm, femoral with the arteries of the leg),

referred to as intersystem, or long, roundabout paths. To internal

organ connections include connections between blood vessels

inside the organ (between the arteries of neighboring lobes of the liver). External

ganny (between the branches of the own hepatic artery in the collar

tah of the liver, including with the arteries of the stomach). Anatomical

pre-existing collaterals after ligation (or occlusion

thrombus) of the main arterial trunk at-

take on the function of conducting blood to the peripheral

affairs of a limb (region, organ). Moreover, depending on

anatomical development and functional sufficiency of the number

laterals, three opportunities are created to restore blood

treatment: the anastomoses are wide enough to completely

ensure blood supply to tissues, despite turning off the ma-

hystral artery; anastomoses are poorly developed, roundabout blood

circulation does not provide nutrition to the peripheral parts,

ischemia occurs and then necrosis; there are anastomoses, but the volume

the blood flowing through them to the periphery is small for full

blood supply, in connection with which the

newly formed collaterals. The intensity of collateral-

blood circulation depends on a number of factors: anatomical

features of pre-existing lateral branches, diameter

arterial branches, the angle of their departure from the main trunk,

the number of side branches and the type of branching, as well as on the functional

the normal state of the vessels (from the tone of their walls). For volumetric

of the blood flow, it is very important whether the collaterals are in spasmodic

bath or, conversely, in a relaxed state. Exactly

the functional capabilities of collaterals determine the regional

hemodynamics in general and the value of regional peri-

spherical resistance in particular.

To assess the sufficiency of collateral circulation

it is necessary to keep in mind the intensity of metabolic processes

in a limb. Taking into account these factors and influencing them

using surgical, pharmacological and physical

ways to maintain limb viability

or any organ with functional failure

pre-existing collaterals and promote the development of new

emerging blood flow paths. This can be achieved either

activating collateral blood circulation, or reducing

tissue consumption of nutrients supplied by the blood

and oxygen. First of all, the anatomical features are pre-

existing collaterals must be taken into account when choosing

places where the ligature is applied. It is necessary to spare as much as possible

large lateral branches and apply a ligature as needed

possibilities below the level of their departure from the main trunk.

Has a certain significance for collateral blood flow

the angle of departure of the lateral branches from the main trunk. The best

conditions for blood flow are created with an acute angle of discharge

lateral branches, while the obtuse angle of departure of the lateral branches

vessels complicates hemodynamics due to increased hemo-

dynamic resistance. When considering anatomical

the features of pre-existing collaterals need to be taken into account -

show varying degrees of severity of anastomoses and conditions

for the development of newly formed blood flow pathways. Naturally,

that in those areas where there are many muscles rich in blood vessels, there are

and the most favorable conditions for collateral blood flow

ka and neoplasms of collaterals. It must be taken into account that

when a ligature is applied to an artery, irritation occurs

sympathetic nerve fibers, which are vasoconstrictors -

mi, and a reflex spasm of collaterals occurs, and from

blood flow, the arteriolar link of the vascular bed is switched off.

Sympathetic nerve fibers pass through the outer sheath

arteries. To eliminate reflex spasm of collaterals

and maximum opening of arterioles, one of the ways is -

the intersection of the artery wall along with the sympathetic nerves

management of periarterial sympathectomy. Similar

the effect can be achieved by introducing novocaine into the periarterial

new fiber or novocaine blockade of sympathetic nodes.

In addition, when crossing an artery due to divergence

its ends there is a change in the right and obtuse angles of the exit

dividing the lateral branches to a more favorable location for blood flow

angle, which reduces hemodynamic resistance and spores

improves collateral circulation.

Let us examine the development of collateral circulation of the heart vessels using the example of atherosclerosis of the coronary arteries. Coronary atherosclerosis has certain patterns of development: atherosclerotic plaques develop primarily in places most susceptible to mechanical pressure or stretching or pulse wave shock. The angiographic picture of atherosclerosis of the coronary arteries consists of symptoms of arterial patency disorders and symptoms reflecting compensation processes.

TO the most important features These include primarily narrowing of the arteries or their occlusion, marginal filling defects or their equivalent - uneven contrasting of the vessel. With atherosclerosis, significant tortuosity of the coronary arteries may be observed. Greatest diagnostic value have tortuosity of the circumflex branch of the left coronary artery, since its shape is least related to phase changes in configuration and heart size.

A sign of atherosclerosis is the unevenness of the lumen of the coronary artery. Normally, the arteries gradually narrow in the distal direction. With atherosclerosis, in some places they have a cylindrical shape, in some places narrowings occur with subsequent expansions.

Compensation for impaired coronary blood flow is primarily collateral circulation.

The number and diameter of collaterals increase depending on the severity of the atherosclerotic process, especially they are expressed at the border of the myocardial zones fed by the left and right coronary arteries, as well as along the edge of the ischemic zone.

Anatomically, the coronary arteries are anastomosing. In a healthy heart, there are a huge number of intra- and intercoronary anastomoses, however, coronary anastomoses do not normally function. Intracoronary anastomoses connect the branches of one coronary artery or several branches of the basin of one coronary artery, intercoronary anastomoses connect the basins of the right and left coronary arteries. Intracoronary anastomoses within one branch are presented in the form of short arterial shunts connecting segments of one vessel with a small segmental occlusion. With extended blockage, intracoronary anastomoses are presented in the form of long connections connecting one of the branches to another branch of this artery. Short shunts are formed from tiny vessels located in the epicardium around the coronary artery and dilate in the presence of a small segmental occlusion. The value of this kind of anastomosis is small, since they are unlikely to provide sufficient blood flow. Of greater importance are anastomoses of another kind, connecting segments of arteries through lateral branches. Thus, when the anterior interventricular or circumflex branch is blocked, compensatory blood flow occurs through anastomoses of the diagonal branches with the marginal branch of the circumflex artery. With the extreme left type of blood circulation, when the posterior interventricular branch is formed by the circumflex artery, blood flow can occur through the septal branches, which in this case are intracoronary anastomoses.

Intercoronary anastomoses are numerous and connect the basin of the right and left coronary arteries. Intercoronary blood flow is especially intense through the septal branches, through the branches of the pulmonary cone and branches to the right ventricle. On the diaphragmatic surface, the branches of the right coronary artery anastomose with the branches of the circumflex branch of the left coronary artery.

In the coronary artery system, the following main pathways of collateral circulation can be distinguished (Fig. 30.).

1. Anastomoses connecting the anterior and posterior interventricular branches. This path is most common (in 90% of all collaterals). Typically, these anastomoses connect the right coronary artery to the anterior interventricular branch.
2. Anastomoses of the anterior interventricular branch of the left coronary artery with the right coronary artery in the region of the anterior wall of the right ventricle. Especially great importance have anastomoses with a conical branch, which can arise either from the right coronary artery or an independent trunk in the area of the right coronary sinus of the aorta. These anastomoses in the area of the base of the pulmonary artery form the so-called Tebezia-Viessen circle.
3. Anastomoses between the anterior interventricular and circumflex branches of the left coronary artery.
4. Anastomoses between the right coronary artery and the left circumflex branch on the diaphragmatic surface of the left ventricle.
5. Anastomoses between the perforating branches of the anterior and posterior interventricular branches (as a rule, these anastomoses connect the system of the right coronary artery and the anterior interventricular branch of the left).

Fig.30.

1 - between conical branches; 2 - between the right ventricular branches; 3 - between the posterior interventricular branch and the posterior ventricular branch of the circumflex branch; 4 - between the anterior and posterior septal branches; 5 - between the terminal branches of the posterior interventricular branch and the branches of the posterolateral branch (branches of the obtuse edge); 6 - between the posterior interventricular and anterior interventricular branches in the area of the apex of the heart (apical anastomoses); 7 - between the first diagonal and posterolateral branches.

When assessing the condition of the coronary arteries according to coronary angiography, the anatomical type of blood supply to the heart, location, extent and degree of narrowing are also taken into account.

There are three main types of coronary blood supply (Fig. 31):

1. Right type- the right coronary artery predominates. It forms the posterior interventricular branch, which reaches the apex of the heart along the posterior longitudinal groove.
2. Left type- blood supply back wall heart (including the posterior wall of the right ventricle) is carried out mainly due to the circumflex branch of the left coronary artery, forming the posterior interventricular branch.
3. Uniform (balanced) type- both coronary arteries have evenly developed branches on back surface heart and form two parallel posterior interventricular arteries.

Fig.31.

(1 - right coronary artery, 2 - left coronary artery, 3 - circumflex branch. A - left type, B - right type, C - balanced type).

The type of blood supply can significantly influence the course of coronary heart disease. For example, occlusions in the left coronary artery system are most unfavorable with the left type of blood supply.

– blood pressure gradient above and below the narrowed section of the vessel;

– accumulation in the ischemic zone of biologically active substances with a vasodilating effect (adenosine, acetylcholine, Pg, kinins, etc.);

– activation of local parasympathetic influences (promoting the expansion of collateral arterioles);

– high degree development of the vascular network (collaterals) in the affected organ or tissue.

Organs and tissues, depending on the degree of development arterial vessels and anastomoses between them are divided into three groups:

– with absolutely sufficient collaterals: skeletal muscles, intestinal mesentery, lungs. In them, the total lumen of the collateral vessels is equal to or greater than the diameter of the main artery. In this regard, cessation of blood flow through it does not cause severe tissue ischemia in the region of blood supply to this artery;

– with absolutely insufficient collaterals: myocardium, kidneys, brain, spleen. In these organs, the total lumen of the collateral vessels is significantly less than the diameter of the main artery. In this regard, its occlusion leads to severe ischemia or tissue infarction.

– with relatively sufficient (or, which is the same thing: with relatively insufficient) collaterals: the walls of the intestines, stomach, bladder, skin, adrenal glands. In them, the total lumen of the collateral vessels is only slightly smaller than the diameter of the main artery. Occlusion of a large arterial trunk in these organs is accompanied by a greater or lesser degree of ischemia.

Stasis: a typical form of regional circulatory disorder, characterized by a significant slowdown or cessation of blood and/or lymph flow in the vessels of an organ or tissue.

What is collateral circulation

The physiological characteristics of the body make it possible to supply blood through vessels that are located parallel to the main ones. Such systems have a medical name - collaterals, which is translated from Greek as “circuitous”. This function allows you to ensure uninterrupted blood supply to all organs and tissues in case of any pathological changes, injuries, or surgical interventions.

Types of collateral circulation

In the human body, collateral circulation can have 3 types:

Absolute or sufficient. In this case, the sum of collaterals that will slowly open is equal to or close to the main vessels. Such lateral vessels perfectly replace pathologically altered ones. Absolute collateral circulation is well developed in the intestines, lungs and all muscle groups.
Relative, or insufficient. Such collaterals are located in the skin, stomach and intestines, and bladder. They open more slowly than the lumen of a pathologically altered vessel.
Insufficient. Such collaterals are unable to completely replace the main vessel and allow blood to fully function in the body. Insufficient collaterals are located in the brain and heart, spleen and kidneys.

As medical practice shows, the development of collateral circulation depends on several factors:

individual structural features of the vascular system;
the time during which the blockage of the main veins occurred;
age of the patient.

It is worth understanding that collateral circulation develops better and replaces the main veins at a young age.

How is the replacement of the main vessel with a collateral one assessed?

If the patient has been diagnosed with serious changes in the main arteries and veins of the limb, the doctor assesses the adequacy of the development of collateral circulation.

To give a correct and accurate assessment, the specialist considers:

metabolic processes and their intensity in the limbs;
treatment option (surgery, medications, and exercises);
the possibility of full development of new pathways for the full functioning of all organs and systems.

Numerous medical observations have shown that for the full opening of collaterals, it is necessary to block the reflex spasm in the nerve endings. Such a process may occur because when a ligature is applied to an artery, irritation of the semantic nerve fibers occurs. Spasms can block the full opening of the collateral, so such patients are given novocaine blockade of the sympathetic nodes.

SHEIA.RU

Collateral Circulation

The role and types of collateral circulation

The term collateral circulation implies the flow of blood through the lateral branches into the peripheral parts of the limbs after blocking the lumen of the main (main) trunk. Collateral blood flow is an important functional mechanism of the body, due to the flexibility of blood vessels and is responsible for uninterrupted blood supply to tissues and organs, helping to survive myocardial infarction.

The role of collateral circulation

The largest ones, taking on the role of a switched off artery immediately after blockage, are called anatomical or preceding collaterals.

Groups and types

Depending on the localization of intervascular anastomoses, previous collaterals are divided into the following groups:

Intrasystemic - short paths of roundabout circulation, that is, collaterals that connect the vessels of the large arteries.
Intersystem - roundabout or long paths that connect the basins of different vessels with each other.

Collateral circulation is divided into types:

Intraorgan connections are intervascular connections within a separate organ, between muscle vessels and the walls of hollow organs.
Extraorgan connections are connections between the branches of the arteries that supply a particular organ or part of the body, as well as between large veins.

Anatomical development of collaterals

Collaterals can be divided into the following groups:

sufficiently developed, characterized by wide development, the diameter of their vessels is the same as the diameter of the main artery. Even complete closure of the main artery has little effect on the blood circulation of such an area, since anastomoses fully replace the decrease in blood flow;
insufficiently developed ones are located in organs where intraorgan arteries interact little with each other. They are usually called ring ones. The diameter of their vessels is much smaller than the diameter of the main artery.
relatively developed ones partially compensate for impaired blood circulation in the ischemic area.

Diagnostics

What is collateral blood flow?

Clinical and topographic anatomy is studied and such important question as collateral circulation. Collateral (roundabout) blood circulation exists under physiological conditions when there is temporary difficulty in blood flow through the main artery (for example, when blood vessels are compressed in areas of movement, most often in the joint area). Under physiological conditions, collateral circulation occurs through existing vessels running parallel to the main ones. These vessels are called collaterals (for example, a. collateralis ulnaris superior, etc.), hence the name of the blood flow - “collateral circulation”.

Collateral blood flow can also occur in pathological conditions - with blockage (occlusion), partial narrowing (stenosis), damage and ligation of blood vessels. When blood flow through the main vessels becomes difficult or stops, blood rushes through anastomoses into the nearest lateral branches, which expand, become tortuous, and gradually connect (anastomose) with existing collaterals.

Thus, collaterals exist under normal conditions and can develop again in the presence of anastomoses. Consequently, in case of a disorder of normal blood circulation caused by an obstacle to the blood flow in a given vessel, the existing bypass blood paths, collaterals, are first turned on, and then new ones develop. As a result, blood bypasses the area with impaired vessel patency and blood circulation distal to this area is restored.

To understand collateral circulation, it is necessary to know those anastomoses that connect systems of various vessels through which collateral blood flow is established in the event of injury and ligation or during development pathological process leading to blockage of the vessel (thrombosis and embolism).

Anastomoses between the branches of large arterial highways that supply the main parts of the body (aorta, carotid arteries, subclavian, iliac arteries, etc.) and representing, as it were, separate vascular systems are called intersystem. Anastomoses between the branches of one large arterial line, limited to the limits of its branching, are called intrasystemic.

No less important are anastomoses between systems of large veins, such as the inferior and superior vena cava, and the portal vein. The study of anastomoses connecting these veins (cavo-caval, portocaval anastomoses) in clinical and topographic anatomy much attention is paid.

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Ultrasound scanner, Doppler: Ultrasound Dopplerography of the lower extremities

Portable ultrasound scanner with color and power Doppler

Ultrasound Dopplerography of the lower extremities

(Selected chapter from the Educational and Methodological Manual "CLINICAL DOPPLEROGRAPHY OF OCCLUSING LESIONS OF THE ARTERIES OF THE BRAIN AND LIMB". E.B. Kuperberg (ed.) A.E. Gaidashev et al.)

1. Anatomical and physiological features of the structure of the arterial system of the lower extremities

The internal iliac artery (IIA) supplies blood to the pelvic organs, perineum, genitals, and gluteal muscles.

The external iliac artery (EIA) supplies blood hip joint and the head of the femur. The direct continuation of the IFA is the femoral artery (FA), which arises from the IFA at the level of the middle third of the inguinal ligament.

The largest branch of the BA is the deep femoral artery (DFA). It plays a major role in the blood supply to the thigh muscles.

The continuation of the BA is the popliteal artery (PclA), which begins 3-4 cm above the medial epicondyle of the femur and ends at the level of the neck of the fibula. The length of PklA is approximately cm.

Fig.82. Scheme of the structure of the arterial system of the upper and lower extremities.

The anterior tibial artery, having separated from the popliteal, runs along the lower edge of the popliteal muscle to the gap formed by it with the neck of the fibula on the outside and the posterior tibial muscle on the bottom.

Distal to the PTA is in the middle third of the leg between the extensor pollicis longus muscle and the tibialis anterior muscle. On the foot, the PTA continues into the dorsalis pedis artery (terminal branch of the PTA).

The posterior tibial artery is a direct continuation of the PclA. Behind the medial malleolus, midway between its posterior edge and the medial edge of the Achilles tendon, it passes to the base of the foot. The peroneal artery departs from the PTA in the middle third of the leg, supplying blood to the muscles of the leg.

Thus, the direct source of blood supply to the lower extremity is the IPA, which passes into the femoral ligament below the Pupart ligament, and three vessels provide blood supply to the lower leg, two of which (PTA and PTA) supply blood to the foot (Fig. 82).

Collateral circulation in lesions of the arteries of the lower extremities

Occlusive lesions of various segments of the arterial system of the lower extremities, like any other arterial systems, lead to the development of compensatory collateral circulation. The anatomical prerequisites for its development are inherent in the very structure of the arterial network of the lower limb. There are intrasystemic anastomoses, that is, anastomoses connecting the branches of one large artery, and intersystemic, that is, anastomoses between the branches of different vessels.

When the IPA is affected in any area up to the level of origin of its two branches - the inferior epigastric and deep, surrounding the ilium, collateral blood supply is carried out through intersystem anastomoses between the branches of these arteries and the IPA (iliopsoas, obturator, superficial and deep gluteal arteries) (Fig. 83).

Fig.83. Occlusion of the right IPA with filling of the BA through collaterals.

When the BA is affected, the branches of the GBA widely anastomose with the proximal branches of the PclA and constitute the most important roundabout path (Fig. 84).

When the PCL is damaged, the most important intersystem anastomoses are formed between its branches and the PTA (network of the knee joint). In addition, the branches of the PclA to the posterior group of muscles of the lower leg and its branches to knee joint form a rich collateral network with the branches of the GBA. However, collateral flows in the PclA system do not compensate blood circulation as fully as in the BA system, since collateral compensation in any of the vascular systems with distal lesions is always less effective than with proximal ones (Fig. 85).

Fig.84. Occlusion of the right BA in the middle third with collateral flow through the branches of the GAB (a) and filling popliteal artery(b).

Fig.85. Distal damage to the arteries of the leg with poor collateral compensation.

The same rule corresponds to collateral compensation in case of damage to the tibial arteries. The terminal branches of the PTA and PTA are anastomosed on the foot widely through the planetary arch. In the foot, the dorsal surface is supplied with blood by the terminal branches of the anterior, and the plantar surface by the branches of the posterior tibial arteries; between them there are numerous perforating arteries that provide the necessary compensation for blood circulation when one of the tibial arteries is damaged. However, distal involvement of the PCL branches often leads to severe ischemia that is difficult to treat.

The severity of ischemia of the lower limb is determined, on the one hand, by the level of occlusion (the higher the level of occlusion, the more complete collateral circulation) and, on the other hand, the degree of development of collateral circulation at the same level of damage.

2. Technique for examining the arteries of the lower extremities

Examination of patients using the Doppler ultrasound method is carried out using sensors with frequencies of 8 MHz (PTA and PTA branches) and 4 MHz (BA and PclA).

The technique for examining the arteries of the lower extremities can be divided into two stages. The first stage is the location of blood flow at standard points with obtaining information about its nature, the second stage is the measurement of regional blood pressure with the registration of pressure indices.

Location at standard points

Almost along the entire length, the arteries of the lower extremities are difficult to locate due to their great depth. There are several projections of vascular pulsation points, where the location of the blood flow is easily accessible (Fig. 86).

These include:

the first point in the projection of Scarp's triangle, one transverse finger medial to the middle of the Pupart ligament (point of the external iliac artery); the second point in the region of the popliteal fossa in the PclA projection; the third point is localized in the fossa formed anteriorly by the medial malleolus and posteriorly by the Achilles tendon (ATA);
the fourth point in the dorsum of the foot along the line between the first and second phalanges (terminal branch of the PTA).

Fig.86. Standard location points and Dopplerograms of the arteries of the lower extremities.

Locating blood flow at the last two points can sometimes be somewhat difficult due to the variability in the course of the arteries in the foot and ankle.

When locating the arteries of the lower extremities, Dopplerograms normally have a three-phase curve, characterizing the usual main blood flow (Fig. 87).

Fig.87. Dopplerogram of the main blood flow.

The first antegrade pointed high peak characterizes systole (systolic peak), the second retrograde small peak occurs in diastole due to retrograde blood flow towards the heart until the aortic valve closes, the third antegrade small peak occurs at the end of diastole and is explained by the occurrence of weak antegrade blood flow after blood is reflected from aortic valve leaflets.

In the presence of stenosis above or at the location, as a rule, an altered main blood flow is determined, which is characterized by a biphasic amplitude of the Doppler signal (Fig. 88).

Fig.88. Dopplerogram of altered main blood flow.

The systolic peak is flatter, its base is expanded, the retrograde peak may not be expressed, but is still most often present, there is no third antegrade peak.

Below the level of arterial occlusion, a collateral type of Dopplerogram is recorded, which is characterized by a significant change in the systolic peak and the absence of both retrograde and second antegrade peaks. This type of curve can be called monophasic (Fig. 89).

Fig.89. Dopplerogram of collateral blood flow.

Regional pressure measurement

The value of arterial systolic pressure, as an integral indicator, is determined by the sum of the potential and kinetic energy possessed by the mass of blood moving in a certain area of the vascular system. The measurement of arterial systolic pressure by ultrasound is, in essence, the registration of the first Korotkoff sound, when the pressure created by the pneumatic cuff becomes lower than the arterial pressure in a given section of the artery so that minimal blood flow appears.

To measure regional pressure in individual segments of the arteries of the lower limb, it is necessary to have pneumatic cuffs, essentially the same as for measuring blood pressure on the arm. Before starting the measurement, blood pressure is determined in the brachial artery, and then at four points in the arterial system of the lower limb (Fig. 90).

The standard cuff arrangement is as follows:

the first cuff is applied at the level of the upper third of the thigh; the second - in the lower third of the thigh; the third - at the level of the upper third of the lower leg;
fourth - at the level of the lower third of the leg;

Fig.90. Standard arrangement of pneumatic cuffs.

The essence of measuring regional pressure is to register the first Korotkoff sound during sequential inflation of the cuffs:

the first cuff is designed to determine systolic pressure in the proximal BA; the second - in the distal part of the BA; the third - in PklA;
the fourth is in the arteries of the lower leg.

When recording blood pressure at all levels of the lower extremities, it is convenient to locate the blood flow at the third or fourth points. The appearance of blood flow, recorded by the sensor with a gradual decrease in air pressure in the cuff, is the moment of fixation of systolic blood pressure at the level of its application.

In the presence of hemodynamically significant stenosis or occlusion of the artery, blood pressure decreases depending on the degree of stenosis, and in the case of occlusion, the degree of its decrease is determined by the severity of the development of collateral circulation. Blood pressure in the legs is normally higher than in the upper limbs approximately namm.Hg.

The topical value of measuring blood pressure in the legs is determined by sequentially measuring this indicator over each of the arterial segments. Comparison of blood pressure figures gives a sufficient idea of the state of hemodynamics in the limb.

Greater objectification of measurement is facilitated by the calculation of the so-called. indices, that is, relative indicators. The most commonly used is the ankle pressure index (API), calculated as the ratio of arterial systolic pressure in the PTA and/or PTA to this indicator in the brachial artery:

For example, blood pressure at the ankle is 140 mmHg, and at the brachial artery, mmHg, therefore, LID = 140/110 = 1.27.

With an acceptable blood pressure gradient in the brachial arteries (up to 20 mm Hg), the ADP is taken according to the larger indicator, and in case of hemodynamically significant damage to both subclavian arteries the LID value drops. In this case, the absolute numbers of blood pressure and its gradients between individual vascular segments become more important.

Normal LID is between 1.0 and 1.5 at any level.

The maximum fluctuation of the LID from the upper to the lower cuff is no more than 0.2-0.25 in one direction or another. An LID below 1.0 indicates an arterial lesion proximal or at the measurement site.

Scheme of examination of the arteries of the lower extremities

The patient is in the supine position (with the exception of the examination of PCL, which is located when the patient is positioned on his stomach).

The first step is to measure blood pressure in both upper extremities.

The second stage consists of sequential location of standard points with obtaining and recording Dopplerograms of the NPA, BA, PTA and PTA.

It should be noted that it is necessary to use a contact gel, especially when locating the dorsal artery of the foot, where the subcutaneous fat layer is quite thin, and location without creating a kind of “cushion” of gel can be difficult.

The frequency of the ultrasound sensor depends on the artery being located: when locating the external iliac and femoral arteries, it is advisable to use a sensor with a frequency of 4-5 MHz, when locating smaller PTA and PTA - with a frequency of 8-10 MHz. The sensor must be installed so that arterial blood flow is directed towards it.

To carry out the third stage of the study on standard areas of the lower limb (see. previous section) pneumatic cuffs are applied. To measure blood pressure (with subsequent conversion to LID) in the IPA and BA, registration can be carried out at 3 or 4 points on the foot, when measuring blood pressure in the arteries of the leg - sequentially at both 3 and 4 points. Blood pressure measurements at each level are carried out three times, followed by selecting the maximum value.

3. Diagnostic criteria occlusive lesions of the arteries of the lower extremities

When diagnosing occlusive lesions of the arteries of the lower extremities using Doppler ultrasound, the nature of blood flow with direct location of the arteries and regional arterial pressure. Only a combined assessment of both criteria allows an accurate diagnosis to be made. However, the nature of the blood flow (mainline or collateral) is still a more informative criterion, since with a well-developed level of collateral circulation, LID values can be quite high and mislead regarding damage to the arterial segment.

Isolated lesion of individual segments of the arterial network of the lower limb

With moderately severe stenosis that does not reach hemodynamic significance (from 50 to 75%), the blood flow in this arterial segment has an altered main character, proximal and distal (for example, for BA, the proximal segment is the IPA, the distal segment is the PCL), the nature of the blood flow is main, LID values do not change throughout the entire arterial system of the lower limb.

Occlusion of the terminal aorta

When the terminal aorta is occluded, collateral blood flow is recorded at all standard location points on both limbs. On the first cuff, LID is reduced by more than 0.2-0.3; on the remaining cuffs, LID fluctuations are no more than 0.2 (Fig. 91).

It is possible to differentiate the level of aortic damage only angiographically and according to duplex scanning data.

Fig.91. Occlusion of the abdominal aorta at the level of the origin of the renal arteries.

Isolated occlusion of the external iliac artery

When the IPA is occluded, collateral blood flow is recorded at standard location points. On the first cuff, LID is reduced by more than 0.2-0.3; on the remaining cuffs, LID fluctuations are no more than 0.2 (Fig. 92).

Isolated femoral artery occlusion

in combination with GAB damage

When the BA is occluded in combination with a lesion of the GAB, the main blood flow is recorded at the first point, and collateral at the other points. On the first cuff, LID is reduced more significantly due to the exclusion of GAB from collateral compensation (LID can decrease by more than 0.4-0.5); on the remaining cuffs, LID fluctuations are no more than 0.2 (Fig. 93).

Isolated occlusion of the femoral artery below the origin of the GAB

When the BA is occluded below the level of the outlet of the GAB (proximal or middle third), the main blood flow is recorded at the first point, in the rest - collateral, as well as with occlusion of the BA and GAB, but the decrease in LID may not be as significant as in the previous case, and differential diagnosis with an isolated lesion of the IPA is carried out based on the nature of the blood flow at the first point (Fig. 94).

Fig.94. Isolated occlusion of the BA in the middle or distal third

With occlusion of the middle or distal third of the BA at the first point there is a main blood flow, at the rest there is a collateral type, while the LID on the first cuff is not changed, at the second it is reduced by more than 0.2-0.3, at the rest - LID fluctuations are not more than 0.2 (Fig. 95).

Fig.95. Isolated occlusion of PCL

With PclA occlusion, the main blood flow is recorded at the first point, collateral at the rest, while the LID on the first and second cuff is not changed, on the third it is reduced by more than 0.3-0.5, on the fourth cuff the LID is approximately the same as on the third (Fig. 96).

Isolated occlusion of the arteries of the leg

When the arteries of the leg are damaged, the blood flow is not changed at the first and second standard points, at the third and fourth points there is collateral blood flow. The ankle pressure index does not change on the first, second and third cuffs and sharply decreases on the fourth by 0.5 -0.7, down to an index value of 0.1 -0.2 (Fig. 97).

Combined damage to segments of the arterial network of the lower limb

Interpretation of data is more difficult in cases of combined lesions of the arterial network of the lower extremity.

First of all, an abrupt decrease in LID (more than 0.2-0.3) below the level of each of the lesions is determined.

Secondly, a kind of “summation” of stenoses is possible with a tandem (double) hemodynamically significant lesion (for example, IAD and BA), while collateral blood flow can be recorded in a more distal segment, indicating occlusion. Therefore, it is necessary to carefully analyze the data obtained taking into account both criteria.

Occlusion of the IPA in combination with damage to the BA and peripheral bed

In case of occlusion of the IPA in combination with damage to the BA and peripheral blood flow, collateral blood flow is recorded at standard location points. On the first cuff, LID is reduced by more than 0.2-0.3; on the second cuff, LID is also reduced by more than 0.2-0.3 compared to the first cuff. On the third cuff, the difference in LID in comparison with the second is no more than 0.2; on the fourth cuff, a difference in LID of more than 0.2 -0.3 is again recorded (Fig. 98).

Occlusion of the BA in the middle third in combination with damage to the peripheral bed

With occlusion of the BA in the middle third in combination with damage to the peripheral bloodstream, the main blood flow is determined at the first point, at all other levels - collateral blood flow with a significant gradient between the first and second cuffs, on the third cuff the decrease in LID compared to the second is insignificant, and on the fourth cuff again there is a significant decrease in LID down to 0.1-0.2 (Fig. 99).

PCL occlusion in combination with peripheral lesions

With PclA occlusion in combination with peripheral lesions, the nature of the blood flow is not changed at the first standard point; at the second, third and fourth points, the blood flow is collateral. The ankle pressure index does not change on the first and second cuffs and sharply decreases on the third and fourth by 0.5 -0.7 down to an index value of 0.1 -0.2.

Infrequently, but simultaneously with PclA, not both, but one of its branches are affected. In this case, an additional lesion of this branch (PTA or PTA) can be determined by separate measurement of the LID on each of the branches at points 3 and 4 (Fig. 100).

Thus, with combined lesions of the arteries of the lower extremity, various options are possible, but careful adherence to the study protocol will avoid possible mistakes in making a diagnosis.

Also, the task of more accurate diagnosis is answered by automated expert diagnostic system determination of the pathology of the arteries of the lower extremities “EDISSON”, which allows, based on objective indicators of the pressure gradient, to determine the level of damage to these arteries.

4. Indications for surgical treatment

Indications for reconstruction of the aortoiliac, aortofemoral, iliofemoral and femoropopliteal segments of the arteries of the lower extremities

Indications for reconstructive operations on the arteries of the lower extremities with damage to the aorto-femoral-popliteal zones are quite widely covered in domestic and foreign literature, and their detailed presentation is inappropriate. But it is probably worth recalling their main points.

Based on clinical, hemodynamic and arteriographic criteria, the following indications for reconstruction have been developed:

Graduation I: severe intermittent claudication in an active individual, negatively affecting work ability, inability to change lifestyle with an adequate assessment by the patient of the risk of surgery (chronic ischemia of the lower limbs, grade 2B-3, reducing the patient’s quality of life);

In general, indications for surgical treatment are determined individually, depending on the patient’s age, concomitant diseases and lifestyle. Thus, a clinical picture of intermittent claudication even after meters without pain at rest and without trophic disorders is not yet an indication for surgery, if this situation does not reduce the patient’s “quality of life” (for example, moving mainly by car, mental work). There is also the exact opposite situation, when intermittent claudication over meters, but taking into account the patient’s specialty (for example, employment in the field of heavy physical labor) makes him incapacitated and gives indications for surgical reconstruction. However, in any case, surgical reconstruction should be preceded by medical treatment, including, along with vasoactive and antiplatelet drugs, smoking cessation and an anti-cholesterol low-calorie diet.

Graduation II: pain at rest that is not amenable to non-surgical conservative treatment (chronic ischemia of the lower limbs grade 3, psychoasthenia);

Graduation III: A non-healing ulcer or gangrene usually limited to the toes or heel or both. Ischemic pain at rest and/or tissue necrosis, including ischemic ulcers or fresh gangrene, are indications for surgery if appropriate anatomical conditions exist. Age rarely acts as a reason for contraindications to reconstruction. Even in elderly patients, TLBAP can be performed along with drug treatment if surgical reconstruction is not possible due to the patient’s somatic condition.

Indications for grade I are for functional improvement, grades II and III are for salvage of the lower limb.

The frequency of atherosclerotic lesions of the arteries of the lower extremities is different (Fig. 101). Most common cause chronic ischemia is damage to the femoral-popliteal (50%) and aorto-iliac zones (24%).

The types of operations used for the surgical treatment of chronic ischemia of the lower extremities are extremely diverse. The bulk of them are so-called. bypass operations, the main purpose of which is to create a bypass shunt between unchanged sections of the vascular bed above and below the area of arterial damage.

Fig. 101. Frequency of atherosclerotic lesions of the arteries of the lower extremities.

1- aorto-iliac, 2- femoral-popliteal, 3- tibial,

4 - iliofemoral, 5 - popliteal zones.

In accordance with the frequency of damage to the arteries of the lower extremities, the most frequently performed operations are femoral-popliteal bypass (Fig. 102) and aorto-femoral bifurcation (Fig. 103a) or unilateral (Fig. 103b) bypass. Other operations of direct and indirect revascularization of the arteries of the lower extremities are performed much less frequently.

Fig. 102. Scheme of the femoropopliteal bypass operation.

B Fig.103. Aorto-femoral bifurcation (a) and unilateral (b)

Transluminal balloon angioplasty of the arteries of the lower extremities

Like all treatments vascular diseases, indications for the use of TLBAP are based on clinical and morphological criteria. Of course, TLBAP is indicated only for “symptomatic” patients, that is, for those in whom damage to the arterial bed of the lower extremities is accompanied by the development of ischemic symptoms to varying degrees severity - from intermittent claudication to the development of gangrene of the limb. At the same time, if for surgical reconstruction (see the previous section) the indications are strictly defined only for severe ischemia, and for intermittent claudication the issue is resolved individually, then for TLBAP the clinical indications can be presented much wider due to the lower risk of complications and mortality.

Serious complications during surgical treatment also occur very rarely, but nevertheless, the risk of complications with TLBAP, if all conditions of the procedure are met and the indications are correctly established, is even lower. Therefore, clinical indications for TLBAP should not only include patients with critical ischemia of the lower extremities (rest pain or arterial ischemic ulcers, incipient gangrene), but also patients with intermittent claudication, which reduces the quality of life.

Anatomical indications for TLBAP: ideal:

short stenosis of the abdominal aorta (Fig. 104); short stenosis involving the aortic bifurcation including the mouths of the common iliac arteries; short stenosis of the iliac artery and short occlusion of the iliac artery (Fig. 105); short single or multiple stenosis of the superficial femoral artery (Fig. 106a) or its occlusion of less than 15 cm (Fig. 106b);
short stenosis of the popliteal artery (Fig. 107).

Fig. 104. Angiogram of arterial stenosis.

Fig. 105. Angiogram of iliac abdominal aortic stenosis (arrow).

B Fig.106a. Angiograms of stenosis (a) and occlusion (b) of BA before and after TLBAP.

Fig. 107. Angiogram of popliteal artery stenosis.

Some types of lesions can also undergo TLBAP, but with lower efficiency than in the group of “ideal” patients:

prolonged stenosis of the common iliac artery;
short stenoses of the branches of the popliteal artery below the knee joint.

However, prolonged stenoses in the IAS and noncircular prolonged stenoses of the abdominal aorta may be indicated for TLBAP if there are serious contraindications for surgical reconstruction, although it should be emphasized again that the short-term and long-term effectiveness may be reduced.

Contraindications are based on anatomical considerations, but must always be weighed in light of the risk of TLBAP in relation to alternative procedures (surgical or medical treatment).

The following situations may be accompanied by low efficiency and, most importantly, high risk complications with TLBAP:

prolonged occlusion of the iliac artery due to its tortuosity; iliac artery occlusion, but which clinically and/or angiographically can be suspected as thrombosis;
the presence of aneurysms, especially the iliac and renal arteries.

In some cases (relatively recent occlusion), targeted thrombolytic therapy can be effective, the use of which is advisable before TLBAP.

In the presence of calcium deposits at the site of stenosis, TLBAP may be risky due to possible dissection or rupture of the artery. However, the use of transluminal atherotomy has expanded the capabilities of the method and made it feasible in these situations.

An important aspect of the use of TLBAP is the possibility of combining this method with surgical treatment, including:

TLBAP of iliac artery stenosis before femoropopliteal bypass or other distal procedures; TLBAP restenosis;
TLBAP of existing shunts, but with a narrow thread-like lumen of the latter.

Thus, TLBAP can be used either as an alternative to surgical treatment, or as an aid to this type of treatment, or can be used before or after surgical treatment in a selectively selected group of patients.

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Ultrasound scanner, Doppler: Ultrasound Dopplerography of the lower extremities

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