Compensatory processes for local circulatory disorders. Collateral circulation. Anastomosis. Collateral

Collaterals develop from pre-existing anatomical channels (thin-walled structures with a diameter of 20 to 200 nm), as a result of the formation of a pressure gradient between their beginning and end and chemical mediators released during tissue hypoxia. The process is called arteriogenesis. It has been shown that the pressure gradient is about 10 mmHg. sufficient for the development of collateral blood flow. Interarterial coronary anastomoses are presented in different quantities at different types: they are so numerous guinea pigs, which can prevent the development of MI after sudden coronary occlusion, whereas they are virtually absent in rabbits.

In dogs, anatomical channel density may account for 5-10% of resting pre-occlusion blood flow. Humans have a slightly less developed collateral circulatory system than dogs, but there is marked interindividual variability.

Arteriogenesis occurs in three stages:

• the first stage (first 24 hours) is characterized by passive expansion of pre-existing channels and activation of the endothelium after the secretion of proteolytic enzymes that destroy the extracellular matrix;
• the second stage (from 1 day to 3 weeks) is characterized by the migration of monocytes into the vascular wall after the secretion of cytokines and growth factors that trigger the proliferation of endothelial and smooth muscle cells and fibroblasts;
• the third phase (3 weeks to 3 months) is characterized by thickening of the vascular wall as a result of deposition of the extracellular matrix.

In the final stage, mature collateral vessels can reach up to 1 mm in lumen diameter. Tissue hypoxia may favor collateral development by affecting the vascular endothelial growth factor gene promoter, but this is not a primary requirement for collateral development. Among the risk factors, diabetes may reduce the ability to develop collateral vessels.

A well-developed collateral circulation can successfully prevent myocardial ischemia in humans following sudden collateral occlusion, but rarely provides adequate blood flow to meet myocardial oxygen demands during maximal exercise.

Collateral vessels can also be formed by angiogenesis, which involves the formation of new vessels from existing ones and usually results in the formation of capillary network-like structures. This was clearly demonstrated in a study of thoracic artery implants in canine myocardium with progressive complete occlusion of the main artery. coronary artery. The collateral blood supply provided by such newly formed vessels is quite small compared to the blood supply provided by arteriogenesis.

Filippo Crea, Paolo G. Camici, Raffaele De Caterina and Gaetano A. Lanza

Chronic ischemic heart disease

Collateral blood circulation (s. collateralis: synonym K. roundabout) K. along vascular collaterals, bypassing the main artery or vein.

Large medical dictionary. 2000 .

See what “collateral circulation” is in other dictionaries:

COLLATERAL BLOOD CIRCULATION- (collateral circulation) 1. Alternative path the passage of blood through the side blood vessels when the main ones are blocked. 2. Arteries connecting the branches of the coronary arteries supplying the heart. At the apex of the heart they form very complex... ... Dictionary in medicine

1. An alternative route for blood to pass through the side blood vessels when the main ones are blocked. 2. Arteries connecting the branches of the coronary arteries supplying the heart. At the apex of the heart they form very complex anastomoses. Source:… … Medical terms

I Blood circulation (circulatio sanguinis) continuous movement of blood through a closed system of cavities of the heart and blood vessels, providing everything vital important functions body. The directional flow of blood is due to the pressure gradient, which... ... Medical encyclopedia

- (p. collateralis) see Collateral circulation... Large medical dictionary

- (p. reducta) collateral K. in the limb after ligation of the vein according to Oppel, characterized by a reduced but balanced inflow and outflow of blood ... Large medical dictionary

CIRCULATION- Structure evolution diagram circulatory system. Scheme of the evolution of the structure of the circulatory system: I fish; II amphibians; III mammals; 1 pulmonary circulation, 2 big circle blood circulation: p … … Veterinary encyclopedic dictionary

REDUCED CIRCULATION- REDUCED CIRCULATION, a concept introduced by Oppel in 1911 to designate a condition when a limb lives on collateral circulation (both arterial and venous) in cases where forced ligation ...

Blood supply to the heart muscle; carried out through interconnected arteries and veins that penetrate the entire thickness of the myocardium. The arterial blood supply to the human heart occurs mainly through the right and left coronary... ... Great Soviet Encyclopedia

I Stroke Stroke (late Latin insultus attack) acute disorder cerebral circulation, developmental persistent (lasting more than 24 hours) focal neurological symptoms. During I. complex metabolic and... ... Medical encyclopedia

ANEURYSM- (from the Greek aneuryno I expand), a term used to denote the expansion of the lumen of an artery. From the concept of A. it is customary to separate arter and ectasia, which are a uniform expansion of the system of any artery with its branches, without ... ... Great Medical Encyclopedia

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 circulation caused by an obstacle to the flow of blood in this vessel, first the existing bypass blood pathways - collaterals - are turned on, and then new ones develop. As a result, impaired blood circulation is restored. In this process important role the nervous system plays.

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 various vessels, through which collateral blood flow is established in case of vascular injuries, ligation 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 great vessels V 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.

The term collateral circulation implies the flow of blood through the lateral branches into peripheral parts 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:

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

Collateral circulation is divided into types:

1. Intraorgan connections - intervascular connections inside separate body, between the vessels of the muscles and the walls of the hollow organs.
2. 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 vessels; anatomical features 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 speed metabolic processes in the limbs. Knowing this indicator and competently influencing it with the help of physical, pharmacological and surgical methods, the vitality of an organ or limb can be maintained and the development of new blood flow pathways can be stimulated. To do this, you need to reduce oxygen consumption by tissues and nutrients supplied with blood, or activate 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 exposed to mechanical pressure or stretching or shock of the pulse wave. 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 left circumflex branch coronary artery, since its shape is least related to phase changes in the configuration and size of the heart.

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 healthy heart there is 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 be carried out through the septal branches, which in 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. The indicated anastomoses in the base area pulmonary artery form the so-called circle of Tebesia - Viessin.
• 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 coronary disease hearts. For example, occlusions in the left coronary artery system are most unfavorable with the left type of blood supply.