BLOOD CIRCULATION

From Big Medical Encyclopedia

BLOOD CIRCULATION — the continuous motion of blood on a loop system of cardial cavities and blood vessels promoting ensuring all vital functions of an organism. With the help To. to fabrics the oxygen, nutrients, water and salts arriving from the environment are delivered and carbonic acid, end products of a metabolism are removed from fabrics. At the highest animals and the person To. — necessary link gas exchange (see) and heat exchange of an organism with the environment (see. Thermal control ). With the help To. transfer of hormones and other physiologically active agents from one bodies to others is carried out and thus functioning of an organism as complete system is provided.

System effectiveness To. in implementation of transport of substances in an organism, on the one hand, is defined by opportunities of repeated increase regional and the general To., and with another — properties most blood (see). So, unit volume of an arterial blood in conditions fiziol. rest contains much more oxygen and nutrients, than gives them to fabrics. Therefore at a fixed level of a blood-groove transport of oxygen to cells can increase if necessary due to fuller return of oxygen hemoglobin. Existence of such reserve of oxygen means that fabrics can receive normal amount of oxygen at reduction of a blood-groove three times and only at further reduction of a blood-groove intake of oxygen to cells will be broken. On this basis it is accepted that so-called coefficient of safety To. on oxygen it is equal to 3. The glucose oxidized by oxygen has the same coefficient of safety as oxygen. Thus, the amount of oxygen and glucose necessary for fabrics can determine the level of a fabric blood-groove.

HISTORY

Observations testimonial of the correct understanding of function K., were available already in works of scientists of Ancient China (3 century BC).

In 4 century BC Aristotle observed heart beat at the developing chicken embryo. Erazistrat (3 century BC) found a zapustevaniye of arteries after death and mistakenly assumed that they bear to fabrics air. This direction was developed by the Roman doctor and the scientist, the founder of experimental medicine K. Galen (2 century AD).

According to K. Galen's representations, the food processed in a stomach and intestines passes then on channels into a liver where becomes a source of a krovoobrazovaniye; blood is carried then on veins to various parts of a body where it is consumed. The part of blood coming to a right ventricle of heart gets through openings of a partition into a left ventricle where mixes up with air and then, enriched with «vital spirits», comes to all parts of a body, including and to a brain. In a brain blood turns into the «animal spirits» necessary for the movement of each part of a body. In the Middle Ages this representation about To. became the traditional dogma which existed apprx. 1500.

In Renaissance there were Leonardo da Vinci, A. Paré, A. Vezaliya's works which called into question a number of the basic moments of the scheme of Galen. One of important events of this period was the description of a small circle To., made M. Servet.

In 1628 the English doctor At. Garvey described the experimental methods of studying developed by it To. also stated some philosophy of physiology and medicine close to modern. Having measured amount of the blood which is contained in an organism of animals it showed what only through one extremity in several minutes proceeds blood more, than its contains in all organism. U. Garvey came to a valid conclusion that blood repeatedly is returned to the same body part, i.e. moves around. At the same time U. Garvey did not understand still the nature of communication between arteries and veins and assumed that blood filters through «a time of fabrics». Therefore opening by M. Malpigi and A. Levenguk of existence of capillaries gave to U. Garvey's doctrine completeness. Garvey's opening showed a way for the successful solution of important issues of applied medicine. So, Elskholtts (S. Elsholtz, 17 century) showed that more bystry to lay down. the effect of medicine is shown after its introduction directly to blood. In 1733 S. Hales for the first time took direct measurement of pressure of blood in arteries and veins of various animals.

In 19 century deeper studying began To., and also bonds between To. and breath. The big contribution to it was made Poiseuille (J. M of Poiseuille), K. Ludvig, E. Marey, I. M. Sechenov, E. Pflyuger, J. Barkroft, I. R. Tarkhanov, etc. At a boundary of 20 century many, including clinical methods of a research K were developed. — a pletizmografiya, a hemadromometry, a sfigmografiya, a manometriya in various vessels, methods of registration and the analysis of the electric phenomena in heart — an electrocardiography, etc. Use of new methods of a research promoted deeper studying of the main funkts, properties of heart and fiziol, the mechanisms controlling function of heart and vessels. So, brothers Webers (E. Weber and E. F. W. Weber, 1845) brothers I. F. and M. F. Tsiony (1866), and then I. P. Pavlov (1887) — a promoting effect of a sympathetic nerve established the braking action on heart of a vagus nerve; A. P. Walther (1842) and K. Bernard (1852) opened vasoconstrictor nerves. The esodic nerves and barorecrptor reflexogenic zones participating in regulation of arterial pressure (I. F. Dion, K. Ludvig, E. Goering, K. Geymans) were allocated.

In 1871 F. V. Ovsyannikov described a vasomotor center of a myelencephalon.

V. Ya. Danilevsky, N. A. Mislavsky and V. M. Bekhterev showed changes To. at irritation of various sites of a cerebral cortex and subcrustal structures.

Basic value for understanding of questions of regulation To. and all activity of system K. in general had I. P. Pavlov's doctrine about reflex regulation To. normal and at its disturbances.

In 20 century studying of the main properties of heart, various vessels and laws of a hemodynamics [A. Krog, Uiggers continues (Page J. Wiggers), V. V. Voronin, H. N. Savitsky]. Successful development got a job on studying of reflex mechanisms of regulation To. (K. M. Bykov, V. N. Chernigovsky, V. V. Parin); P. K. Anokhin formulated the doctrine about funkts, system as a basis of self-control of an organism and its major functions, in particular systems K.

Since 50th 20 century in development of the doctrine about To. three most essential tendencies were outlined. First, there was a representation that at all importance of the hydrodynamic phenomena in line with system K. (see. Hemodynamics ) they are considerably predetermined by sokratitelny function of a cross-striped muscle of heart and smooth muscles of vessels. In this regard studying of cellular and molecular mechanisms of processes of excitement, reduction and relaxation in heart and vessels began; and also influences on these processes of mediators of nervous excitement and hormones. Secondly, creation of the telemetric sensors implanted in an organism capable to transfer information to distance, made possible a research K. in normal conditions — during various behavioural reactions of an animal. In these researches function K. it is studied not separately and as a link of set of adaptive reactions of a complete organism. At last, in connection with emergence of new methods of intravital studying To. broad development was gained by researches in which questions of physiology and pathology To. decide directly on the person — there was a wedge, physiology and a pathophysiology To.

The COMPARATIVE PHYSIOLOGY

At the elementary organisms metabolic communication of an organism with the environment is carried out by simple diffusion of gases and other substances through a cellular membrane. In an organism of the lowest metazoans between cells the intercellular lymph forms, through it the metabolism between various cells, and also penetration of gases, water and other substances from the environment and removal of end products of exchange from an organism is carried out. Invertebrates (arthropods, mollusks) and at the lowest chordates have special liquid — a hemolymph, edge on not loop system of tubes reaches various parts of a body where vessels are interrupted by cracks, lacunas deprived of own walls. The hemolymph mixes up with an intercellular lymph, gets into intercellular spaces and is returned to heart.

Characteristic feature of evolution of system K. gradual isolation of the device K is. in a loop system; short circuit of this system of tubes for the first time was outlined at annlides. At the same time there was gradual structural and funkts, an isolation of specialized muscular body — heart, a cut plays a role of the pump providing the movement of blood on vessels. At some lowest chordate animals, napr, at a lancelet, the role of such pump carries out a belly vessel, at worms — back. Arthropod mollusks already had an isolation of heart that considerably increased efficiency To.

The subsequent stages of evolutionary development To. are followed by allocation big and small (pulmonary) circles To. and corresponding gradual division of heart into 2, 3 and 4 cameras. Fishes have only one circle To., and heart is divided into two cameras: from a ventricle all blood goes to gills, from where, enriched with oxygen, it is distributed on all body and then is returned to an auricle. At animals with lung respiration two circles of blood circulation form and additional cameras of heart appear. So, at amphibians and the majority of reptiles heart three-chambered: the blood flowing from fabrics comes to the right auricle, and the blood which passed a small circle and enriched with oxygen — to the left auricle. In a ventricle there is mixing of blood then it is distributed between easy and all other bodies and fabrics again. Escaping of an aqueous medium on the land in the conditions of the increased gravitation imposed new requirements to system K. — the mass of heart increased, vascular walls etc. underwent changes.

At the highest reptiles — crocodiles and at mammals in connection with full division To. into small and big circles there is a division of a ventricle on left and right: in the right half of heart only a venous blood, in left — only arterial, arriving then in all fabrics and body organs circulates.

In the course of evolution of system K. there was a gradual improvement of «urgent» information bonds of system K. with other systems that is promoted by development of an innervation of bodies of system K. Heart of most primitive vertebral (cycloostomies) is absolutely deprived of nervous bonds, at fishes the innervation of heart is carried out only by a vagus nerve and, apparently, there is no sympathetic innervation yet. These features are defined by rather low adaptive ability To. these animals living in conditions of stabler environment than land animals. Emergence of a land way of life caused development numerous and various nervous and improvement of humoral bonds of heart and vessels with other bodies. These bonds provide urgent mobilization of system K. for participation in adaptive reactions of an organism.

At mammals the movement of blood happens on two vicious circles — big and small circles of system K. On a big circle blood comes from a left ventricle of heart to an aorta and further to all bodies and body tissues from where on venous system is returned to the right auricle. Having passed from it into a right ventricle of heart, blood comes through a pulmonary artery to lungs from where about four pulmonary veins to the left auricle (a small circle are returned To.).

The PHYSIOLOGY

the Energy source, blood, necessary for ensuring advance, on vascular system, is work hearts (see). Reduction of a cardiac muscle reports to blood the energy spent for overcoming elastic forces of walls of vessels and giving of speed to a stream of blood. A part of the energy reported to blood accumulates in elastic walls of large arteries owing to their stretching. During a diastole of a wall of arteries are reduced, and the energy accumulated in them turns eventually into a motive energy of moving blood. Thus, despite the rhythmic nature of cordial activity, the blood stream in peripheral vessels is supported continuously. Return of a venous blood to heart, owing to the fact that it moves from lower body against gravity is promoted by a number of factors: 1) the part of energy remaining in a flow of blood after passing by it of arteries and capillaries; 2) the negative pressure which is available in a chest cavity at the time of a breath (on 2 — 5 mm of mercury. below atmospheric), the providing suction of blood to heart; 3) the reduction of skeletal muscles and a diaphragm promoting pushing through of blood towards heart (valves of veins obstruct the traffic of a venous blood in the opposite direction).

Various sites of vascular system have a row biophysical, the features influencing function K. They can be divided into five groups.

1. The main vessels — aorta (see) and large arteries (see). Their walls contain a little muscular tissue and many elastic fibers owing to what have considerable distensibility and elasticity. These vessels provide transformation of sharply pulsing blood-groove in more uniform and smooth.

2. Vessels of resistance — small arteries, arterioles. In walls of these vessels there are a lot of muscle fibers promoting active change of a gleam that significantly influences the general peripheric resistance of system K.

3. Exchange vessels — capillaries (see) — the most important elements of system K., providing a metabolism between blood and fabrics. The quantity of the functioning capillaries in each site of fabric depends from funkts, and metabolic activity and can change in considerable limits (see. Microcirculation ).

4. Vessels of the shunt — an arteriolovenulyarny anastomosis — provide dumping of blood from arteries in veins, passing capillaries (see. Arteriovenous anastomosis ), what has important fiziol, value in the conditions of action of cold on an organism and in some other cases.

5. Capacity vessels — veins (see) — have the biggest distensibility and rather low elasticity. Veins contain 70 — 80% of all blood of an organism and determine highly the capacity of all system K., the size of return of blood to heart and the minute volume

of K. O a condition of function K. in a complete organism it is possible to judge on the basis of definition of the following its main indicators.

The minute volume of blood (MO) — the amount of the blood which is thrown out by heart in 1 min., expected as the work systolic, or shock, the volume (amount of the blood which is thrown out for one reduction) number of reductions of heart in 1 min. Theoretically minute volume of the blood which is thrown out left and right by ventricles of heart, and also the amount of blood passing in 1 min. through any site of a big or small circle of blood circulation are identical. At rest size MO makes 5,0 — 5,5 l, at physical. to loading it can increase by 2 — 4 times, and at the trained athletes — by 6 — 7 times. In the conditions of pathology, e.g., at dekompensirovanny heart diseases, primary hypertensia of a small circle and other cases, MO about 2,5 — 1,5 l can decrease.

The volume (weight) of the circulating blood (OTsK) normal makes 75 — 80 ml of blood on 1 kg of body weight. At physical. to loading it increases owing to an exit of blood from depot (see. Blood depot ). At to blood loss (see), shock , (see), collapse (see) OTsK decreases (hypovolemia), and at dekompensirovanny heart diseases — increases, reaching 140 — 190 ml/kg (hypervolemia).

Time of a circulation of blood — time, during to-rogo a particle of blood passes a big and small circle. Normal it makes 20 — 25 sec., decreasing at physical. to loading and increasing at disturbances To. (to 50 — 60 sec.). Time of a circulation through a small circle normal makes 7 — 11 sec.; at stagnation in a small circle To., napr, at dekompensirovanny mitral defect, this time can increase to 19 — 21 sec.

Distribution of blood in an organism is characterized by sharply expressed irregularity. At the person the blood stream in ml on 100 g of the weight (weight) of body in 1 min. averages at rest: in kidneys — 420, in heart — 84, in a liver — 57, in a brain — 53, in cross-striped muscles — only 2,7, i.e. is 150 times less, than in kidneys. Sizes of a blood-groove in various fabrics and bodies at rest and during execution of physical. the works expressed as a percentage to the minute volume of blood are given in table 1:

Table 1. Distribution of a blood-groove (in % of the minute volume of blood) in different departments of vascular system of the person at rest and during a heavy exercise stress [across Folkou and Nile (V. of Folkow, E. Niel), 1976]



Such distribution of blood provides compliance between blood supply of bodies and their function. It depends on an unequal tone of vessels in various bodies since blood in a vascular bed moves in the ways with the smallest resistance and in the greatest number comes to those vessels which tone is lower, and the gleam is wider. At physical. to loading vessels of cross-striped muscles extend, the minute volume of blood increases and distribution changes. At the same time the most part of blood will come to vessels of muscles; for blood supply of all other bodies there are 15 — 20% of volume of all blood. In the conditions of pathology at reduction of minute volume distribution of blood changes and provides preferential supply of vitals.

The structure and properties of vessels of heart, a brain and lungs provide rather favorable conditions of blood supply of these bodies. So, to a muscle of heart, weight a cut makes 0,4% of body weight, arrives at rest apprx. 5% of all blood, i.e. in 10 times more, than to all fabrics on average. At big loadings the coronary blood stream can increase by 10 — 15 times, reaching 3000 — 4600 ml/min. At the general decrease in minute volume of blood in the conditions of pathology its share falling on coronary vessels increases (to 10 — 12% of the minute volume of blood) and therefore the coronary blood stream in these conditions either does not change, or increases. Necessary size coronary circulation (see) it is provided with also high density of a capillary network and big surface area of the capillaries inherent to vascular system of heart. So, if in skeletal muscles at the maximum vasodilatation 300 — 400 capillaries on 1 mm open 3 , in a muscle of heart in the same conditions from 2500 to 4000 capillaries open.

To a brain, weight to-rogo is equal to 2% of body weight, at rest nearly 15% of all blood arrive: the brain consumes 20% of the oxygen coming to an organism; most of all blood (about 100 ml on 100 g in 1 min.) is consumed by bark of big hemispheres, it is less (apprx. 20 — 25 ml on 100 g in 1 min.) — white matter of a brain.

To. in lungs, carried out on rather small pressure gradient (10 — 15 mm of mercury.), it is facilitated at the expense of the low resistance of pulmonary vessels. This feature is caused by the small extent of a way, on Krom there passes blood within a small circle To., rather large diameter of pulmonary arteries and high distensibility of vessels of lungs; increase in a blood-groove in lungs at loading highly is promoted by tendency of vessels of lungs to passive stretching.

Rather more favorable conditions of blood supply of vitals are created due to features of a .stroyeniye and properties of vessels of these areas, mechanisms of regulation To. in these bodies.

Regulation of blood circulation

Regulation of blood circulation provides the size of a blood-groove in fabrics and bodies corresponding to the level of their function due to regulyatorno the determined changes of minute volume of blood and resistance of regional departments of a vascular bed.

Regulation To. it is possible to subdivide into self-control and neurohumoral regulation conditionally.

Self-control is carried out constantly and makes a necessary link of regulation To., and its mechanisms are put in a design of the system K. and in its interrelations with with other bodies and systems. In particular, at the animals deprived of a head and spinal cord directly after switching off of nervous control the falling of the ABP caused by reduction of peripheric resistance is observed. However both of these parameters within several hours are recovered to norm. As an example of the mechanisms determined by the structure of system serve mechanisms of self-control of cardiac performance. So, in response to increase in inflow of blood and additional stretching of cavities of ventricles there is an increase in amplitude of reduction and a stroke output — the law of Starlinga (see. Starlinga law ). This mechanism operates because at stretching of myocardial cells the zone of contact between octynic and miozinovy protofibrils increases and the number of aktomiozinovy bridges between them and consequently, and force of reduction of a cardiac muscle increases. Other mechanism of self-control of heart consists that at increase in resistance to exile of blood octynic and miozinovy protofibrils slowly slide relatively each other. As a result exposure time of active centers of a myosin and actin increases, the number of aktomiozinovy bridges and as a result force of reduction increases. Both of these phenomena are implemented on the muscle fibers deprived of a sarcolemma and are an example phylogenetic of the ancient and reliable mechanism of self-control To., the managed object put in the structure, i.e. in structure of myofibrils of myocardial cells. These mechanisms play a role in regulation of function K. and in the conditions of a healthy organism.

One of mechanisms of self-control in system K. Ostroumov's phenomenon — Beylissa, being that at increase in the ABP unstriated muscles of arterioles are reduced is, causing vasoconstriction. Decrease in the ABP has opposite effect. Similar autoregulyatorny reactions, quantitatively differing in different vascular areas, provide constancy of level of perfusion of this or that fabric in the conditions of fluctuation of size ABP.

Self-control of volume of blood and the ABP is implemented due to close interrelation To. and secretory function of kidneys it is also shown in the form of so-called pressor diuresis (see). The essence of this phenomenon consists that at increase in the ABP there is an increase in pressure in capillaries of renal balls, increase of filtering and a diuresis. At patients with an idiopathic hypertensia the same mechanism operating under control of neuroendocrinal regulation is the reason of the increased diuresis.

On the basis of interrelation between fabric microcirculation and a condition of cells the most important mechanisms of self-control providing compliance between a blood-groove in bodies and the level of their function are implemented. The fact that in the course of metabolism some of its products are formed in cells in the quantity proportional to their activity is the cornerstone of functioning of these mechanisms. These substances are capable to expand precapillary arterioles and to increase quantity opened — functioning — capillaries according to intensity of activity of fabric (see. Microcirculation ). At increase in intensity of activity of cells of skeletal muscles or any other fabrics formation of ATP lags behind the need for it in the beginning. As a result the amount of ATP decomposition products increases. The arisen surplus of ADF and AMF activates resynthesis of ATP in mitochondrions, increases oxygen consumption in a cell in general (see. Phosphorylation ). The surplus of adenosine which arose at the same time brakes transport of calcium ions in cells of smooth muscles of arterioles and by that promotes their expansion. As a result there is an increase in a fabric blood-groove necessary for ensuring the increased oxygen requirement, and increase in intensity of synthesis of ATP.

An important role in self-control of a regional blood-groove and consequently, inflow of blood to heart play also kinina (see), prostaglandins (see), histamine (see) and others biologically active agents (see). With their help necessary increase in a blood-groove in the working bodies during the strengthening of loading and other reactions of an organism is provided. Self-control is a necessary link of regulation To., though insufficient to provide fast and considerable changings To., really arising in the course of adaptation of an organism to changes in the environment. The last is reached on the basis of coordination of self-control and neurohumoral regulation of system K.

Neyrogumoralnaya regulation To. it is provided with the difficult mechanism combining afferent, central and efferent links.

The afferent link is presented by receptor fields of the system K. and other receptors, the central link — the cardiovascular center of a myelencephalon and the related centers of a hypothalamus, old and new bark (see. Cerebral cortex ). It is proved that one of the lowest levels of the central regulation To. the spinal cord serves. The efferent link has nervous and endocrine departments. The nervous department is made by preganglionic sympathetic neurons which bodies are located in front horns of chest and lumbar departments of a spinal cord, and the postganglionic neurons located out of a spinal cord. Other its part are the preganglionic parasympathetic neurons located in a kernel of a vagus nerve in a myelencephalon, and also in the lower segments of a spinal cord and the postganglionic parasympathetic neurons located in executive bodies (see. Autonomic nervous system ). The endocrine department is presented brain and cortical by layers adrenal glands (see), back share hypophysis (see) and juxtaglomerular device kidneys (see).

A leading role in neurohumoral regulation To. plays the cardiovascular center of a myelencephalon which is quite often called vasomotor center (see). In it it is possible to allocate three connected among themselves department: 1) group of the neurons located in lateral parts of a myelencephalon; their constant activity through pre-and postganglionic sympathetic neurons exerts the tonic activating impact on function of heart and reduction of smooth muscles of vessels; 2) medially located neurons possessing the opposite (braking) action on post-and preganglionic sympathetic neurons and reducing the activating influence of an adrenergic innervation on To.; 3) dorsalno the located kernel of a vagus nerve exerting the braking impact on heart.

Effector influences, coming from the cardiovascular center of a myelencephalon, form, first, as a result of interaction and processing of the nervous impulses coming to it bearing information from mechanioreceptors, chemoceptors and other receptor fields of system K. Secondly, this direct impact on neurons of a myelencephalon of oxygen, carbonic acid and the hydrogen ions which are contained in blood. Overlying departments of a brain exert impact on the cardiovascular center of a myelencephalon also.

Receptors of system K. are presented by mechanioreceptors of stretching of a carotid sine of an aortic arch, a pulmonary artery, and also auricles and ventricles of heart. According to the location of mechanioreceptors of system K. they are divided into receptors of areas of high and low pressure. Activation of the first has preferential value for regulation of blood pressure, and activation of the second — for regulation of OTsK. The irritation of mechanioreceptors occurs at stretching of walls of vessels the raised ABP and involves increase in intensity of the afferent impulsation coming through carotid and aortal nerves to the cardiovascular center. In reply there is a decrease in tonic activity of sympathetic neurons and excitement of a kernel of a vagus nerve of a vasomotor center. As a result there is a decrease in resistance of a vascular bed and minute volume of heart and normalization of the ABP. Stronger irritation of these receptors involves more expressed reaction in the form of arterial hypotension and bradycardia; decrease in intensity of irritation owing to falling of the ABP at blood loss, on the contrary, leads to increase in tonic excitement of sympathetic neurons and decrease in a tone of vagus nerves. Arisen thereof tachycardia and the increased resistance of a vascular bed, an exit of blood from depot promote recovery arterial pressure (see). Thus, reflexes of mechanioreceptors of an aortal and carotid zone play a role of the regulatory buffer supporting the ABP at the level necessary for an organism.

Receptors of a pulmonary artery also represent the mechanioreceptors of stretching localized in a zone of low pressure and functioning like receptors of an aortal and carotid zone; their strong irritation reduces blood pressure in a big circle To., leads to bradycardia, an apnoea. These receptors play an important role in prevention of possible overloads of a small circle To.

Mechanioreceptors of stretching of auricles are located at the place of falling of venas cava into the right auricle and at the place of falling of pulmonary veins into left; function similar to receptors of an aortal and carotid zone. At irritation of these receptors there is a reflex decrease in tonic activity of sympathetic neurons and increase in a tone of a vagus nerve. At the same time pumping function of heart decreases to a large extent, than resistance of a vascular bed also, thus, is prevented an overload of heart. The area of auricles and the veins falling into them is the most extensible department of all system K., the stretch receptors located here most react to change of filling and play an important role in regulation of volume of the circulating blood. Stretching of the conjunction of pulmonary veins with the left auricle or increase in filling of the left auricle in the conditions of a hyperventilation reflex is followed by increase in a diuresis. It is shown that this reflex can be implemented by two ways. First, the irritation of receptors at a hypervolemia and stretching of auricles involves braking of activity of certain sympathetic neurons of the cardiovascular center and as a result — decrease in resistance of renal vessels, increase in a blood-groove through kidneys, filterings and a diuresis. Increase in a renal blood-groove can be followed by decrease in secretion of a renin the juxtaglomerular device (see. Kidneys ), what leads to reduction of content in blood of the angiotensin activating in usual conditions secretion of Aldosteronum adrenal glands. Secondly, the impulsation from mechanioreceptors caused by stretching of auricles, apparently, reaches not only the cardiovascular center, but also the centers of a hypothalamus, braking activity of the neurons regulating secretion of AKTG, increasing thereby a diuresis. Increase of a diuresis and a natriuresis as a result leads to reduction of OTsK to norm. At the hypovolemia caused by water starvation or blood loss, the same mechanism provides braking of a diuresis and a natriuresis and promotes recovery of OTsK.

Regulation of OTsK, apparently, is not accessory only of mechanioreceptors of auricles and veins. In this process reflexes from other mechanioreceptors since, regulating resistance of a vascular bed, they control, in particular, a ratio of resistance of precapillary and post-capillary vessels (see can play a part. Mikrotsirkulyation ), from to-rogo exchange between a blood plasma and an intercellular lymph depends.

Chemoceptors of system K. are localized in so-called carotid little bodies (see. Paragangliya ), the carotid arteries located in the field of bifurcation and in aortal little bodies. Afferent fibers of carotid little bodies through carotid and aortal nerves go to the cardiovascular center of a myelencephalon. These receptors react to decrease in the oxygen content, increase in content of carbonic acid and hydrogen ions in blood. In reply tachycardia, hypertensia, increase in minute volume of blood develop.

The same reaction To. arises at hypoxias (see), hypercapnias (see), acidosis (see), amplifying when the hypercapnia and acidosis are combined with a hypoxia. Reaction of mobilization To. plays a crucial role in ensuring adaptation To. to conditions physical. works, high-rise hypoxia, blood loss, etc.

Other receptor fields participating in regulation To., are presented intero-and exteroceptors. So, in an experiment it is shown what at perfusion of a vascular bed practically of all abdominal organs which kept with an organism only nervous bonds, irritation of interoretseptor of these bodies change of pressure of perfusate or addition in it various chemical substances involves reflex changes of a vascular tone and cordial activity. Similar reactions can be received at irritation of receptors of skeletal muscles. Fibers from nerve terminations in internals and muscles go to the cardiovascular center of a medulla and a spinal cord and in a considerable part are conductors of painful sensitivity. Normal spinal cardiovascular reflexes are regulated by the descending influences of the cardiovascular center. At damage of conduction paths of a spinal cord they quite often amplify and therefore in response to pain stimulation at patients with damage of a spinal cord of the ABP can raise to dangerous level.

Regulation To. can happen also to participation of thermoreceptors of skin — through the thermoregulatory centers of a hypothalamus, a spinal cord, providing vasoconstriction of skin in response to cold or their expansion in response to thermal influence. All reflexes on the heart and vessels which arose from the listed receptor fields are implemented via the same effector device, i.e. through the spinal sympathetic neurons representing the general final way of all efferent and central influences which through an adrenergic link of regulation affect heart and vessels. These reflexes are carried out also through the parasympathetic neurons stated above and endocrine system. In an endocrine link an important role is played by hormone of marrow of adrenal glands — adrenaline (see), which the same as allocated by sympathetic nerve terminations noradrenaline (see), activates the adenyl cyclase located in an external membrane of muscle cells and through formed 3,5-AMF causes positive other and chronotropic effect on heart, vasoconstriction, reduction of smooth muscles, spleen and other depots of blood (see. Blood depot ). Other necessary links of this system make reninaldosteronovy system (see. Angiotenzin ) and antidiuretic hormone of a back share of a hypophysis (see. Vasopressin ).

Role of the highest departments of c. N of page in regulation To. is defined by the fact that the integrative centers hypothalamus (see), limbic system (see) and certain zones cerebral cortex (see) exert the strong descending impacts on the cardiovascular center of a myelencephalon. These influences form as a result of comparison of information which came to the highest parts of the nervous system from various receptors with previous experience of an organism; they provide implementation of a cardiovascular component emotions (see), motivations (see), behavioural reactions (see. Higher nervous activity ). Before physical. works there is an increase in minute volume of blood, redistribution of a blood-groove and other changes To., making a necessary link of power ensuring future adaptation reaction. Such consecutive system changes To., making a necessary component of all adaptation reactions of an organism, are final result of the descending influences of the highest departments of c. N of page, positive and negative feed-backs from receptors of system K. and mechanisms of self-control.

Blood circulation at advanced and senile age

the General pattern of the growing old organism is decrease in intensity To. in various fabrics, bodies and systems. There is a redistribution of OTsK directed to achievement of optimum blood supply of vitals, first of all a brain and heart. Peripheric vascular resistance both in big, and in a small circle To. raises owing to loss of elasticity of a vascular wall and increase in resistance in small arteries. So, the general peripheric vascular resistance (in dynes-sec.-cm - 5 ) at people of 20 — 49 years makes 1323 ± 62,0; at the age of 60 — 69 years — 2075 ± 122,9; 70 — 79 years — 2286 ± 139,0; 80 — 89 years 2324 ± 108,3; persons have 90 years and are more senior than 2746 ± 212,0.

With age there is a reduction of speed of a blood-groove in all vascular areas, increase in time of the general circulation that it is possible to connect with decrease in cordial emission at increase in capacity of a vascular bed. So, time of a full circulation of blood raises from 47,8 ± 2,7 sec. in 20 — 39 years to 60,6 ± 3,2 in 60 — 69 and to 65,4 ± 3,1 sec. in 70 — 79 years. In 90 years it is also more senior makes 65,0 ± 3,3 sec. There is a delay of a capillary blood-groove promoting fuller saturation of blood oxygen in lungs and its return in fabric in the conditions of reduced permeability of capillaries and the reduced vascularization. Nevertheless decrease in intensity To. at advanced and senile age promotes development of a senile hypoxia owing to disturbance of oxygenation of blood in lungs and deliveries of oxygen in fabric.

At advanced and senile age the nature of regulation changes To., function of neuroreflex mechanisms is easier broken and the role of humoral factors therefore imperfection of regulatory mechanisms in maintenance of optimum level is found To raises. at stressful situations.

Features of blood circulation at children

Organa K. begin to be put on the 2nd week of an antenatal life, to function — from 4th week, formation comes to an end for 3 months. Further they generally increase only in sizes.

The main features pre-natal To. consist in the increased viscosity of blood, existence of an additional circulatory bed in a placenta and a funic cord, rather raised OTsK, big resistance in system of a pulmonary artery, and also in a connection in parallel of both half of heart owing to existence of an oval opening (foramen ovale) and an arterial (botallov) channel (ductus arteriosus Botalli, BNA).

Fig. 5. Diagrammatic representation of blood circulation of a fruit: 1 — an umbilical vein; 2 — a portal vein; 3 — a venous channel; 4 — the lower vena cava; 5 — a hepatic vein; 6 — the right auricle; 7 — an oval opening; 8 — the right pulmonary artery; 9 — an upper vena cava and an aorta; 10 — an arterial channel; 11 — the left auricle; 12 — a pulmonary trunk; 13 — a ventral aorta; 14 — umbilical arteries.

The blood saturated with nutrients and oxygen arrives to a fruit on an umbilical vein from placental fibers (tsvetn. fig. 5). Before portal fissures the branch to a portal vein departs from an umbilical vein. Continuation of an umbilical vein is arantsiyev the channel (ductus venosus Arantii, BNA) falling into the lower vena cava. From it there are branches to a parenchyma of a liver. In the lower vena cava placental blood mixes up with the venous blood arriving from the lower extremities, abdominal organs and a basin. Pressure in the lower vena cava at a fruit is higher, than in the right and left auricles. The lower vena cava falls into the right auricle where falls as well the upper vena cava delivering a venous blood. Thanks to existence in the right auricle of a klapanoobrazny fold (the eustachian gate) apprx. 60% of all blood from the lower vena cava through an oval opening goes to the left auricle, a left ventricle and an aorta. The rest of blood from the lower vena cava and blood from an upper vena cava comes to a right ventricle and a pulmonary artery.

Through lungs of a fruit only 25% of all blood circulating in an organism proceed. It is explained by high resistivity in system of a pulmonary artery. Pulmonary arteries have the expressed muscular layer, their gleam is narrow, and they are in a spazmirovanny state, it is possible in connection with rather low content in blood of oxygen and high content of carbon dioxide gas. Pressure in a pulmonary trunk during a systole rises to 70 — 80 mm of mercury., exceeding pressure in an aorta on average on 10 mm of mercury. Therefore blood from a pulmonary artery through an arterial channel comes to the descending aortic arch below the place of an otkhozhdeniye of the vessels delivering blood to the head and upper extremities of a fruit. On the descending aorta blood goes to lower body. In this regard in the most favorable conditions of food the fruit has a liver, heart, the head and upper extremities that promotes their more bystry development.

Heart at a fruit rather big. By 2,5 months of an antenatal life it makes 10% of the weight (weight) of a body, at the end of pregnancy — 0,8% (children after 3 years have 0,5%). Because the right ventricle works more intensively, than left, the weight of a free part of a right ventricle at the birth is equal 5,2 ± 0,49 g, and the weight of left — 4.3 ± 0,44 g. At a fruit the high frequency of cordial reductions (120 — 160 in 1 min.) and a non-constant rhythm is noted. Duration of a systole exceeds duration of a diastole.

Fig. 6. The diagrammatic representation of blood circulation at the newborn: 1 — a round ligament of a liver; 2 — a portal vein; 3 — the lower vena cava; 4 — a hepatic vein; 5 — the right auricle; 6 — a pulmonary trunk; 7 — an upper vena cava; 8 — an aorta; 9 — an arterial sheaf; 10 — the left pulmonary artery; 11 — the left auricle; 12 — pulmonary veins; 13 — a venous sheaf; 14 — a ventral aorta; 15 — vesicoumbilical sheaves. The arterial blood is designated by red color; dark red — mixed with advantage arterial; violet — mixed with advantage venous; blue — venous; gray — the remains of provisional vessels of a germ.

After the birth of the child there is a sharp reorganization of the blood circulatory system (tsvetn. fig. 6). From the beginning of lung respiration in blood the partial tension of oxygen increases, blood vessels of lungs extend, their krovenapolneniye increases by 4 — 10 times, the small circle begins to function To. Improvement of saturation of blood by oxygen is followed by reduction of number of erythrocytes and, therefore, viscosity of blood. The increased pulmonary blood stream increases pressure in the left auricle, and the termination placental To. reduces pressure in the right auricle that leads to closing of an oval opening.

After shutdown of a placenta of OTsK decreases by 25 — 30%, system vascular resistance is stabilized on more high level, pressure in an aorta increases, the arterial channel is narrowed, and in 2 — 3 months is completely closed.

The most active funkts, and morfol. improvement of cardiovascular system happens within the first three years of life of the child, but also continuous, though uneven development of bodies continues further To.

Unlike adults, at children of early age of an artery have the big width of a gleam in relation to the weight (weight) of heart, gross weight and growth of the child. Venous vessels, on the contrary, are a little narrowed. A ratio between diameter of the corresponding arteries and veins 1:1, while at adults — 1:2. It causes lower the ABP at small children, smaller rate of propagation of pulse wave. With age the weight and volume of heart grows quicker, than a gleam of an artery. By 15 years the volume of heart increases in 7, and a circle of an aorta — by 3 times. Disintegration of weight and volume of heart in comparison with growth of capacity of vascular network at modern children in connection with emergence of acceleration amplified.

Feature To. babies existence of high peripheric vascular resistivity and inadequacy of reactions on patol, irritants is.

Heart rate at children is more, than at adults that is connected with higher intensity of exchange processes and the prevailing influence of a sympathetic innervation.

At children with the developed skeletal muscles pulse is more rare that is caused by increase in activity of a parasympathetic innervation at them. The ABP at children is lower, than at adults, and gradually increases with age.

Venous pressure at children, especially early age, above, than at adults.

Speed of a blood-groove gradually decreases with age in connection with decrease in metabolic rate, an urezheniye of pulse and reduction of amount of the circulating blood by 1 kg of the weight (weight) of the child. The minute volume of a blood-groove at children gradually increases with age preferential due to increase in the systolic volume (tab. 2).

Table 2. Change of size of systolic and minute volumes of a blood-groove at children depending on age [on Gegeshi-Kishsh and Sutreli (P. Gegesi Kiss, D. Szutrely), 1962]



However the relation of size of minute volume of a blood-groove to the weight (weight) characterizing the need of an organism for blood the is more, than the age of the child is less. OTsK of children also decreases with age. So, at newborns size OTsK makes apprx. 103 ml/kg, aged up to 3 years — 89 ml/kg, 4 — 6 years — 81 ml/kg, 7 — 10 years — 80 ml/kg, 11 — 14 years — 78 ml/kg.

Due to the disharmony of development of cardiovascular system in children can arise such funkts, changes as systolic noise, disturbance of a heart rhythm, hypertensia, hypotension, etc.

See also Hemodynamics .

PATHOLOGY

the General mechanisms of disturbances of blood circulation

Disturbances To. are connected with changes of function of heart, arteries, capillaries, veins, changes of rheological properties of the blood flowing on them etc. Certain sites of cardiovascular system in the course of functioning are closely connected among themselves and therefore dysfunction of one of them exerts greater or smaller influence on function another. Disturbances To. can have the general character when function of all circulatory system in general changes, or they can be local when changes concern activity of certain sites of a vascular bed. As continuous and well adjustable To. it is necessary for each body, disturbance it inevitably involves frustration of a metabolism in body and its function up to complete cessation with the subsequent necrosis of fabrics.

Main patterns of disturbance of a hemodynamics. Communication between key parameters of a hemodynamics is usually expressed by the relation: MO = AD/OPS, where MO — the minute volume of blood, the ABP — the level of arterial pressure and OPS — the general peripheric resistance. This relation represents the modified formula of Poiseuille removed for the description of fluid movement in rigid tubes. For system K. this expression is right only as a first approximation. Change of one of parameters (MO or the ABP) affects others not only owing to this pattern (formula). Reduction or increase in cardiac effeciency reflex turns on neurohumoral mechanisms of regulation of a tone of peripheral vessels (influence on OTsK). Similarly regulatory mechanisms at change of the ABP turn on. Thus, studying of ratios between the ABP, MO and OPS allows to understand some general patterns of functioning of system K. So, the size of minute volume of blood is influenced by resistance to a blood flow in openings of cardial cavities. At their stenoses minute volume remains only if pressure respectively grows in ventricles of heart, however it sometimes is not enough, especially at any patol, changes in a myocardium. At the same time the minute volume of blood to a large extent depends also on the volume of blood coming to auricles from venous system. Therefore disturbance of return of a venous blood inevitably involves the corresponding reduction of minute volume of blood.

The general the ABP, i.e. pressure in an aorta and its large branches, depends on the minute volume of blood and the general peripheric resistance. With increase in minute volume of blood or the general peripheric resistance the general raises the ABP — arterial hypertension (see. arterial hypertension ). Under natural conditions the general the ABP depends less often on increase in minute volume of blood (since venous return of blood to heart for this purpose shall increase that demands special conditions) and is more often caused by increase in peripheric resistance owing to a konstriktion of the majority of arteries of an organism. At reduction of these ABP parameters goes down, i.e. there is arterial hypotension (see. Hypotension arterial ), edges, however, depends on reduction of minute volume of blood more, than on primary reduction of resistance to a blood-groove.

The current of blood in any parts of circulatory system is defined by dependence: Q = ΔP/R, t. e. rate of volume flow of a blood-groove (Q) especially increases, than the gradient of pressure (ΔP) throughout this vascular area and than less in it is more than resistance (R). Therefore intensity of a blood-groove in each body and any its part and consequently, and intensity of microcirculation in them also depends from ΔP and R.

For circulatory system of each body the pressure gradient corresponds to arteriovenous swing pressure, i.e. swing pressure between arteries (R art ) and veins (R veins ). Thus, Q = (P art - P veins ) / R. Decrease Rart as well as increase Rven, involves reduction of rate of volume flow of a blood-groove (at invariable resistance throughout vascular system of body). On the other hand, resistance to a blood-groove in this vascular area is defined by hl. obr. resistance in small arteries and arterioles. As soon as this resistance decreases (e.g., at a local vazodilatation), there is an increase in Q, or arterial hyperemia (see). On the contrary, increase in resistance in peripheral arteries (at local vasoconstriction of an embolism etc.) leads to reduction of rate of volume flow of a blood-groove in body — arises ischemia (see). Increase in resistance to a blood-groove can take place and in capillaries of this or that vascular area, napr, owing to intravascular aggregations of erythrocytes (see) at to a staza (see) that in turn can cause reduction of a blood-groove in this body or its part. At last, resistance can increase also in venous system of this body (e.g., owing to thrombosis or a prelum). In these cases in system of microcirculation there is a venous stagnation of blood accompanied with reduction of rate of volume flow of a blood-groove. Thus, though increase in resistance in different parts of circulatory system of bodies is caused by different types of changes of peripheric circulation and microcirculation, but the general for them is reduction of rate of volume flow of a blood-groove of this vascular area.

Mechanisms of dysfunction of heart and vessels

the Main, pumping, function of heart can be broken for the following reasons: owing to reduction of venous return of blood to heart that is usually caused by reduction of OTsK; owing to dekompensirovanny heart diseases, in particular because of insufficiency of the valve device when the incomplete smykaniye of heart valves leads to return of a part of blood in retrogradno the located cardial cavity or there is a stenosis of cordial openings considerably increasing resistance to a blood-groove in them; owing to an amyocardia, reductions a cut do not provide rather high chamber pressure to throw all volume of blood in arterial systems of big and small circles To.; owing to impossibility of sufficient expansion of cardial cavities during a diastole as a result of accumulation of a significant amount of blood (at hemorrhages) or exudate (at perikardita) in a pericardiac cavity or an obliteration of the last owing to hron, a pericardis.

Dysfunctions of peripheral arteries can be connected with changes of their vazomotorika (funkts, expansion or narrowing), with structural changes of their walls (arteriosclerosis) or with full or partial obstruction of a vascular gleam (see. Arteriolosclerosis , Thrombosis , Embolism ). Extent of disturbance To. depends on where there are these changes, in the majority of arteries of an organism or in arteries of separate bodies.

Change of resistance in resistive vessels of separate bodies usually does not affect the level of the general ABP, but leads to changes of blood supply of these bodies. In cases when this resistance decreases (e.g., at a vazodilatation), blood circulation in system of microcirculation of body amplifies — there comes the arterial hyperemia. The last can be not only physiological (e.g., during the strengthening of metabolism in the working muscles), but also pathological — in cases of paralysis of a vasculomotor innervation or vasculomotor neurosises. On the other hand, the increase in resistance in arteries of separate bodies leading to weakening of a blood-groove in them can depend from patol, vasoconstrictions, or vasomotor spasm (see), from sclerous processes in a wall of an artery or from reduction of their gleam up to full embolic occlusion, blood clot or an atheromatous plaque. Reduction of a blood-groove in separate arteries owing to increase in resistance in them not necessarily leads to the corresponding weakening of blood supply of the body supplied by blood these arteries since at the same time there can quickly occur roundabout inflow of blood on collateral arteries (see. Collaterals vascular ). Therefore blood supply of bodies is at once or gradually recovered. However if at increase in resistance in the main arterial trunks supplying with blood this body, collateral inflow of blood is insufficient, then there occurs sharp weakening of microcirculation in the respective sites of fabric, and in them there is ischemia.

Function of venous system considerably differs from function arterial. Veins carry out a drainage of blood from capillaries of all bodies. Resistance in veins rather high can also change only in insignificant degree, and only its increase, but not reduction is possible. Active reductions of unstriated muscles in walls of veins play a small role in increase in resistance since the vazomotorika and a muscular coat in veins is less developed, than in arteries. Increase in resistance in veins is most often caused by their prelum (it happens because of the low intravascular pressure and pliable walls much easier, than in arteries) or thrombosis (rather slow blood stream in veins creates more favorable conditions for formation of blood clots). As a result of increase in resistance in veins outflow of blood from microcirculator system of appropriate authorities is at a loss, and venous stagnation of blood develops.

A role of dysfunction of veins in the general frustration To. it can be caused by their capacity function (i.e. function of depot of blood), from a cut OTsK more depends. At shock (see) the volume of OTsK sharply decreases therefore return of a venous blood to heart is weakened that leads to the corresponding reduction of cordial emission and falling of the general ABP.

Dysfunctions of walls of capillaries cause changes in a transcapillary metabolism (see. Microcirculation ). Function of capillaries depends generally on functions of other parts of system K. and other systems of an organism (respiratory, digestive, mocheotdelitelny). Transcapillary exchange of oxygen and carbon dioxide gas is defined by a difference of partial pressure of these gases in and outside of capillaries. Exchange of water and soluble substances in it depends on intravascular and extravasated pressure, and also on osmolarity of blood and an intercellular lymph. Disturbance of transcapillary balance of water leads to development of hypostases (see. Swelled ). Transcapillary transfer of many substances, including participating in metabolism depends on their active transport through membranes of capillary walls and their barrier properties (see. Barrier functions ).

From changes of hemodynamic indicators in the capillaries influencing all cardiovascular system it is possible to call only changes of viscosity of blood, edges, in turn, most often depends on intravascular aggregation of erythrocytes. Increase in viscosity of blood conducts to different extent of delay of a blood-groove in capillaries up to development of a staz. At the same time food of fabrics is sharply broken that leads even to development necrosis (see) and heart attack (see).

Neurohumoral factors of disturbance of blood circulation

the Various pathogenic factors causing dysfunctions of cardiovascular system can influence heart, arteries, veins, capillaries, and also the blood circulating in them and directly, and via neurohumoral mechanisms by means of which regulation of activity of circulatory system in normal conditions is carried out. Therefore disturbances of activity of the autonomic nervous system, hemadens, and also disturbances of synthesis and turning into an organism of biologically active agents cause various disturbances in system K.

Dysfunction of separate parts of circulatory system depends on neurohumoral factors of subjects more than participation of the last in regulation of their functions is more considerable. Exerts impact on normal cardiac performance not only autonomic nervous system (see), but also various biologically active agents circulating in blood — adrenaline (see), vasopressin (see), serotonin (see), thyroxine (see), etc. Disturbances of datum level of the general ABP more depend on influence of the nervous and humoral factors operating and on cordial activity, and on a tone of walls of peripheral arteries. The tone can change under the influence of vasculomotor nervous impulses or owing to effect of various biologically active agents. Under their influence there can be both a permanent increase in the general ABP, and his decrease coming, e.g., at collapse (see).

The neurohumoral factors operating on an artery can become also the reason of disturbances of blood supply of these or those bodies. However a necessary condition for this purpose is strong vasculomotor influence on arteries of separate bodies or local formation of vasoconstrictive biologically active agents (e.g., prostaglandins) or their specific action on certain arteries (e.g., serotonin on internal sleepy and other large arteries of the basis of a brain).

Disturbances of microcirculation

Disturbances of microcirculation have significant effect on a metabolism and function of the corresponding fabrics and bodies (see. Mikrotsirkulyation ).

For understanding of mechanisms of disturbance of microcirculation it is necessary to consider that not only capillaries, but also branchings of the bringing small arteries and the small veins which are taking away blood from capillaries belong to microcirculator system. The main function of system of small blood vessels is providing such blood-groove in capillaries which is adequate to metabolic requirements of fabric. Disturbances of microcirculation most often depend on changes of inflow of blood from arteries and its outflow in veins, but can depend also on pathology in capillaries.

The disturbances of microcirculation depending on changes of inflow of blood to capillary system from arteries are connected with changes of resistance to a blood-groove throughout the arterial bed supplying this capillary network. At the same time microcirculation can amplify (an arterial hyperemia) or to be weakened (ischemia).

At an arterial hyperemia intra capillary pressure increases that breaks balance of transcapillary exchange of water towards a prevalence of its filtering in fabric over a resorption in blood. Thereof formation of an intercellular lymph and lymph increases, and in the presence of the corresponding conditions there can be edematization of fabric. Increase in a pressure gradient at an arterial hyperemia throughout capillaries increases the speed of a blood-groove in them. At the same time the quantity of the functioning capillaries grows; «dehiscence» of the capillaries closed earlier is connected with increase in intra capillary pressure and falling of «tone» of capillary walls, and also with receipt in capillary system of the blood containing rather bigger quantity of erythrocytes, than usually.

At ischemia key parameters of microcirculation change exactly the opposite: peripheral speed of a blood-groove in capillaries decreases, intra capillary pressure decreases and the quantity of the functioning capillaries decreases. The last depends on transformation of a large number of circulatory capillaries into plasmatic — owing to receipt in capillary system not only smaller amount of blood, but also local reduction of maintenance of erythrocytes in it. Weakening of microcirculation leads to reduction of intake of oxygen in fabric — develops hypoxia (see), one-times but there is a reduction of delivery of power and plastic materials in fabric, and products of metabolism are removed from fabric in smaller quantity. If deficit of blood supply is not eliminated by means of collateral inflow of blood, then changes up to a full necrosis can develop in fabrics owing to disturbances of processes of metabolism various patol.

Disturbances in system of microcirculation happen also at difficulty of outflow of blood in venous system. In this case there is a picture of venous stagnation of blood. Owing to build-up of pressure in veins the pressure gradient throughout capillaries decreases, leading to delay of speed of a blood-groove in them. At the same time, respectively, supply of fabrics with oxygen decreases and the hypoxia develops, supply of fabric with power and plastic materials worsens, and products of metabolism are late in it. As a result of such deficit of blood supply of fabric its mechanical characteristics change: distensibility grows, and elasticity decreases. Under such circumstances increase in intra capillary pressure leads to considerable strengthening of filtering of liquid from capillaries in fabric cracks, and hypostasis develops.

Microcirculation it can also be broken under conditions, when there is no primary changes of inflow of blood to capillaries from arteries or its outflow in veins. It does not depend also on primary changes of width of a gleam of capillaries, and is caused by significant increase in viscosity of blood that, in turn, depends on the strengthened intravascular aggregation of erythrocytes, and the blood stream in capillaries is slowed down in different degree.

Mechanisms of compensation and a decompensation

At pathology To. distinguish two types of compensation closely connected among themselves: purely funkts, compensation, edges it is carried out without structural changes in any parts of cardiovascular system, and compensation which is followed by structural changes (e.g., a hypertrophy of a myocardium). At the same time elimination of these or those disturbances To. can provide funkts, compensation, and restructuring of any parts of cardiovascular system can promote improvement of operation of mechanisms of compensation only. Compensation of disturbances is carried out first of all by the same mechanisms of regulation which function normal.

At pathology in heart compensation can come by means of strengthening of reduction of a myocardium, expansion of cardial cavities, and also a hypertrophy of a cardiac muscle. So, in case of a stenosis of arterial openings (at the beginning of an aorta or a trunk of pulmonary arteries), i.e. at difficulty of exile of blood, the reserve power of the sokratitelny device of cells of a myocardium is implemented and force of reduction of the corresponding ventricle increases. With vrvmeny the compensatory hypertension of ventricles develops. In case of a stenosis of openings between auricles and ventricles pressure in auricles increases, however their hypertrophy does not happen effective due to the lack of valves in mouths of venas cava. Increase intracardiac pressure (see) is followed by growth of the central venous pressure that adversely affects microcirculation.

At insufficiency of these or those valves of heart a part of blood is returned to each following phase of a cardial cycle in the opposite direction. At the same time there is a dilatation of cardial cavities having compensatory character. However excessive dilatation creates unfavorable conditions for cardiac performance since cross-section of a cardial cavity at the same time increases, and a cardiac muscle to create the same pressure, it is necessary to be reduced stronger (see. Hemodynamics ). Besides, if dilatation of cardial cavities reaches a certain degree, blood supply of a myocardium can be broken. The decompensation of cardiac performance can be promoted also various patol, by changes in a cardiac muscle (see. Cardiosclerosis , Myocarditis , Myocardial dystrophy ).

Compensation at the increase in the general ABP caused by increase in the general peripheric resistance in arteries is carried out, in particular, by strengthening of cardiac performance that is necessary for creation of such swing pressure between a left ventricle and an aorta, emission of all systolic volume of blood in an aorta can provide edges. Therefore the myocardium of a left ventricle kompensatorno hypertrophies.

At decrease in the general ABP compensation happens at the expense of the minute volume of heart, increase to-rogo is promoted by transition of blood from depot in system K. and the increase in return of a venous blood caused by it to heart. At the same time there can come the compensatory konstriktion of arteries, edges of subjects more intensively, than the body supplied by them blood is less sensitive to a hypoxia. The maximum vasoconstriction takes place in skin and a fatty tissue, it is less — in parenchymatous bodies, it is even less in kidneys and, at last, the konstriktion is absent and even the vazodilatation in heart and a brain takes place.

At changes of the ABP level in a number of bodies, especially in a brain, compensation is carried out by means of active changes of resistance in arterial system of these bodies. So, at increase in the general ABP there comes the konstriktion of the corresponding arteries of a brain, and resistance so increases in them that the brain blood stream remains normal. Therefore at uncomplicated arterial hypertension intensity of a blood-groove in a brain does not increase. At decrease in the general ABP comes, on the contrary, dilatation of arteries of a brain and a brain blood stream is normalized (it is shown that the brain blood stream can remain not changed during the falling of the general arterial pressure even to 30 mm of mercury with the person.). However such redistribution of blood in a brain can serve as the additional reason of insufficiency of blood supply of internals (a liver, etc.) * Besides, mechanisms of compensation work unequally well, and at each person their work is broken under the influence of various pathogenic factors. In these conditions blood supply of a brain begins to depend on the level of the general ABP more.

At increase in resistance in separate arteries owing to a vasomotor spasm, thrombosis, an embolism etc. disturbance of blood supply of appropriate authority or its part can be compensated for the account of collateral inflow of blood. In some bodies, especially in a brain, such collateral ways are very well presented in the form of an arterial anastomosis in the field of a villiziyev of a circle and in system of pialny arteries on a surface of big hemispheres. Only in the tissue of a brain an interarterial anastomosis is absent, and the available capillary network is not enough for collateral inflow of blood. In addition to existence of an arterial anastomosis, plays an important role for collateral inflow of blood them funkts, dilatation, owing to a cut resistance to a blood-groove considerably decreases, promoting inflow of blood to ishemirovanny area. If in the extended collateral arteries the blood stream is strengthened for a long time, then there comes gradual reorganization of their wall, and the caliber of arteries grows so further they can provide completely blood supply of body as much as the main arterial trunks. However there are cases when after a complete recovery of a blood-groove on collateral ways they can be insufficient over time, napr, owing to age changes of vascular walls (e.g., at arteriosclerosis), and then blood supply of body for the second time is broken.

At increase in resistance in the separate venous vessels which are taking out blood from the small fabric territory or separate body there are great opportunities for compensation for the account of existence of wide network of an anastomosis in venous system. However the blood stream on these collateral ways in venous system can be insufficient, especially at emergence of blood clots in their gleam, and then there comes the decompensation of outflow of blood with the advent of venous stagnation in appropriate authorities.

A circulatory unefficiency

the Aetiology, a pathogeny and a wedge, manifestations of insufficiency To. differ in a variety. They combine existence of an imbalance between oxygen requirement, nutrients and their delivery with blood. The specific reasons of such imbalance, the mechanism of its emergence and signs of manifestation (the general and local) can be various. There is also narrower understanding of insufficiency To., completely corresponding to the value put in the terms «heart failure» and «hron, heart failure». Insisting on understanding of insufficiency To. as equivalent of heart failure, usually refer to the fact that at the same time patol, a state always are mentioned functions of vascular system, in particular vascular dystonia at various levels is observed. E.g., at such form of heart failure, as cardiogenic shock (see), various vascular reactions are observed: increase in a tone of resistive vessels in the first phase of shock and sharp falling — in the second. At chronic heart failure various changes of peripheric vascular resistance and a venous tone connected with a hypoxia of arterial walls, long developments of stagnation in venous system etc. also come to light. Therefore a number of authors designates the specified states not only as a circulatory unefficiency, but also as cardiovascular insufficiency. Along with these terms the term «decompensation of blood circulation» or «decompensation of cordial activity» is sometimes used. However most of the Soviet cardiologists (A. L. Myasnikov, E. I. Chazov, etc.) recommend them not to apply and use the term «heart failure». The term «circulatory unefficiency» (or «circulator insufficiency») in the specified sense and in foreign literature is not applied. At the same time note that primary etiol, a link in similar cases is decrease in pumping function of heart, and these or those changes from a vascular tone have secondary character in these cases. It is possible to speak about cardiovascular insufficiency only when function of heart and a tone of vessels are broken at the same time, napr, under the influence of this or that toxic factor. Critically it is necessary to treat also the concept «decompensation of cordial activity», etc. Really, at various stages of heart failure it is not about a decompensation, and, on the contrary, about turning on of these or those compensatory mechanisms which in a healthy organism at this level of exchange processes do not function. So, at the first stage of heart failure increase of cordial reductions in rest therefore cordial emission increases that allows to provide vital needs of an organism, despite decrease in pumping function of heart is observed. In essence only the end-stage of heart failure can be considered as a decompensation when mobilization of all compensatory mechanisms is not able to provide life activity of an organism.

Generalized insufficiency To. includes also various forms acute and hron, vascular insufficiency, such as syncope (see), collapse (see), shock (see), long decrease in an arterial tone.

Insufficiency To. quite often has also regional character. At the same time the disturbances of a blood-groove caused by vascular impassability as a result of ekstravazalny compression processes, development of intravascular obstacles to a countercurrent (e.g., as a result of atherosclerosis of vessels, vasculites, an embolism, thrombosis, an injury of a vessel) and, at last, disturbances of a vascular tone mean (most often a spasm of arteries and arterioles and decrease in a tone of veins). A wedge, value of regional insufficiency To. depends on what site of vascular system is struck also from extent of the developed disturbances of blood supply. Special value has coronary insufficiency (see), various disturbances of arterial blood supply of a brain (see. Cerebral circulation), vertebrobazilyarny insufficiency, disturbance of blood supply of vessels of extremities (see. Obliterating defeats of vessels of extremities ), etc. In general disturbance of a blood-groove on any artery always constitutes danger to function and integrity of the vascularized body if only this disturbance is not compensated by rather developed collaterals. In a pathogeny of regional manifestations of insufficiency To. the large role is played by disturbances in system of microcirculation: spasms and dystonia of arterioles, staza in capillary system, disturbance of a tone of venules owing to a hypoxia and allocation in a blood channel of biologically active metabolites.

From forms of insufficiency To., developing in venous system, most often it is necessary to deal with disturbances of outflow of blood as a result thrombophlebitis (see) or phlebothrombosis (see), and also decrease in a venous tone (e.g., venous hypotension standing at elderly people).

See also Heart failure , Vascular insufficiency .

METHODS AND DEVICES FOR the RESEARCH of BLOOD CIRCULATION

Exists a large number of various methods and devices allowing to estimate various characteristics of the movement and distribution of blood in an organism and also function of the links which are carrying out these processes. At the same time two main tasks are solved: establishment of the general patterns of functioning of cardiovascular system and detection of functional features To. at a separate individual that is necessary for practical purposes, in particular for diagnosis of various disturbances of blood circulation.

The first methods of a research of blood circulation were based on the simplest ways of obtaining information: sighting, listening, palpation etc. The invention Svammerdamom (J. Swammerdam) in 17 century of a liquid plethysmograph opened an era of tool methods of a research K. In 1733 S. Hales, having read by means of a glass tube blood pressure at a number of domestic animals, in effect offered a method and the device for measurement of one of the major dynamic characteristics by K. Stolety later for this purpose by Poiseuille (J. M of Poiseuille) and K. Ludvig created the liquid and registering manometers. The principle of continuous graphic registration gained bystry development in connection with creation of a kimograf (see. Kimografiya ), the universal pneumatic converter — Marey's capsule.

Emergence of methods and devices for registration of many kardio-and hemodynamic processes belongs to the same period: pulse, speed of a blood-groove, intra esophageal pulsation, pneumopulse, sinkardialny movements of a body.

At the end of 19 — the beginning of 20 century methods of anemic measurement of the ABP [S. Riva-Rocci, were developed 1896; H. S. Korotkov, 1905], the low-inertia optical registering manometer is created [Frank (O. of Frank), 1906 — 1910]. Using it, Frank received the first high-quality records of fluctuations of pressure of blood in cardial cavities and vessels which are objectively reflecting dynamic features of cordial activity. It also improved the principle of air signal transmission, entered a way of optical registration of air fluctuations thanks to what became possible qualitatively to register many other hemodynamic phenomena.

At the beginning of the 30th 20 century the contrast vazografiya at the person which gained late broad development was successfully executed (see. Angiography ).

Development of industrial electronics in the second quarter of 20 century allowed to pass to the electric principles of transformation and signal transmission from the studied object. So. creation of the electronic electrocardiograph promoted broad use in a wedge, practice of electrocardiographical methods of a research (see. Elektrokardiografiya ), the phonocardiography was technically and methodically created. The low-inertia optical manometer of Hamilton used in the beginning for a straight line the nn manometer of heart was replaced by electronic manometers. This period is characterized also by development of other mechanoelectric converters (see. Sensors ) and implementation of new methods of a research: photo-electric, electric, X-ray electric. Development of electronic computer facilities does this direction perspective.

A big role in creation of methods and devices for studying To. belongs to domestic researchers. In 1905 N. S. Korotkov offered the auskultativny principle of measurement of the ABP which became nowadays classical. In 1907 M. V. Yanovsky and A. I. Ignatovsky offered a way of anemic change of speed of a blood-groove, a version to-rogo now is known under the name occlusal pletizmografiya (see). In 1911 V. Voronin and A. A. Bogomolets offered a method of a hemodynamometry in the smallest blood vessels.

A. A. Kedrov in 1941 offered the equipment for reografichesky (reopletizmografichesky) researches (see. Reografiya ). H. N. Savitsky in 1950 created a new complex for hemodynamic researches — the mechanocardiograph intended for complex studying of characteristics of heart, elastic and resistive parameters, arterial and capillary vascular pools (see. Mekhanokardiografiya ). It possesses modern modification of the principle of arterial oscillography (see) and interpretation of the oscillogram inherent to it — a takhoostsillogramma. V. A. Reeben and M. A. Euler created an original way and the device for continuous measurement of the average ABP (see. Blood pressure ).

B. M. Mazhbich (1969) developed a quantitative method of measurement of a local blood-groove of the site of a lung by means of an elektropletizmografiya (see. Pletizmografiya ).

At a research K. there is a problem of obtaining information from unavailable for direct atraumatic approach of areas of an organism. For this purpose in the USSR a number of new methods and devices is developed for a research of a hemodynamics by registration of the secondary phenomena: the torsion movements of a thorax — with the help dinamokardiografiya (see), sinkardialny movements of a body (see. Ballistokardiografiya ), pulsations of air in respiratory tracts; pneumopulse — by means of the pneumocardiograph (see. Cardiography ); precardiac vibrations (see. Seysmokardiografiya ); valve and muscular movements of heart — by means of an ultrasonic valvulografiya and an ultrasonic kinetomiokardiografiya (see. Echocardiography ), etc.

Methods of a research K. divide on bloody and anemic (invasive and noninvasive). A problem of anatomic approach during the determination of the majority of characteristics of system K. and their definition in the necessary body part it is always methodically specific and decides in various ways: carrying out metering devices, their parts or the substances participating in measuring process in a zone, studied or adjacent to it; information retrieval by means of sounding of an organism the getting radiations; use of information of the hemodynamic phenomena reaching a body surface, etc. At the same time along with traditional methods of a research of cardiovascular system the methods based on measurement of electric are implemented impedance (see) and the x-ray density of body tissues (see. X-ray analysis ), specifics of distribution ultrasound (see) in heterogeneous environments, transfer and distribution in an organism of the substances possessing specific physical., properties — isotopes, X-ray contrast, luminescent and other contrast agents.

The important role in obtaining information, unavailable to direct measurements, belongs to indirect measurements at which the required characteristic is found calculation according to measurement of other sizes. This way became traditional during the determination of minute volume of blood, peripheric resistance to a blood flow and some other indicators. However it gains special development with implementation in kardiol, researches of computer facilities thanks to what it was possible to conduct continuous definition of many indicators at catheterization of heart, to visualize processes of reduction of a myocardium, filling and emptying of heart at ultrasonic and radio-gramophones, researches.

Methods of intravital researches of structure of the blood circulatory system

Research of structure of system K. and its links has independent fiziol, value also is an important component of differential diagnosis of congenital anomalies of a structure of heart and the main vessels, the acquired heart diseases, tromboembolic episodes etc. However it must be kept in mind that the research of structure is usually combined with funkts, researches.

The main direction in a research of structure of different departments of cardiovascular system is their visualization.

Radiological methods of a research. Along with traditional methods of radiodiagnosis at a research K. use a number of specialized X-ray diffraction techniques: rentgenofazokardiografiya (see), rentgenokimografiya (see), elektrokimografiya (see), angiography (see), angiocardiography (see), etc. Rentgenofazokardiografiya provides roentgenograms of heart in strictly certain phases of a cardial cycle. Rentgenokimografiya provides the image of movements of contours of a shadow of heart during a cardial cycle. Rentgenokimografiya allows to estimate a stroke output of heart, and also local-kratitelnuyu about function of walls of ventricles of heart. The angiography, though demands introduction to a blood channel of a contrast agent, has high informational content, supplies with the information on features of a structure and patol. changes of system K., the movements of blood that in total allows to diagnose changes of vessels of big and small caliber thanks to what judgment of efficiency of blood supply in the studied zone can be made. Can be an example coronary angiography (see), widely used for identification of defeats of coronary vessels and disturbance of blood supply of a myocardium. By means of a ventrikulografiya it is possible to obtain information on sokratitelny properties of a myocardium, to characterize not only total, but also local sokratitelny function of walls of a left ventricle. The method allows to determine quantitatively end-systolic and final and diastolic volumes, their difference — shock, or systolic, the volume, and also an important indicator of sokratitelny function of a ventricle — the fraction of exile representing the relation of systolic and final and diastolic volumes.

Ultrasonic methods. Important quality of these methods is the full atravmatichnost and suitability for carrying out a research without surgical or other training of the patient. Special one-dimensional echolocators for measurement of thickness of walls of a myocardium and diameter of cameras of heart, and also devices for the two-dimensional image of section of heart in the plane of scanning of an ultrasonic beam are created. At the dorsoventral direction of radiation and scanning in the lateral direction on the screen of the device cross-section of heart is represented. At the same time so-called B-scanners allow to receive the image of heart at certain moments of a sokratitelny cycle, and sectoral scanners — is continuous during all cycle. The method of one-dimensional echolocation allows to diagnose precisely a stenosis of atrioventricular valves, fibrous defeat of shutters of valves and some other changes in heart, and also large vessels. The value of B-scanners first of all is defined by an opportunity to reveal damages of a cardiac muscle, in particular aneurisms, to determine the volume of a left ventricle and other indicators. See also Ultrasonic diagnosis .

Fig. 1. Stsintigramma is normal of a myocardium, executed in a front straight line(s), left front slanting and left side positions. The image has the horseshoe form that corresponds to hypodispersion of radionuclide ( 201 Tl).

Radio isotope scanning — a method of automatic topographical registration of level of radioactivity in various points of the studied body (see. Scanning ). For scanning of cardial cavities intravenously enter any radiotracer (e.g., 131 I-albumine) and by means of the detector of radoactive radiation carry out the graphic representation of area of heart. This method is used for differential diagnosis of endocardiac thromboses, dilatation and a hypertrophy of a cardiac muscle, a pericardis. Scanning of a myocardium is carried out during the use of the indicators collecting in a cardiac muscle. Intravenously enter isotopes 43 K or 201 Tl and through a nek-swarm time by means of the scintillation gamma camera conduct a scintigraphic research (fig. 1). On stsintigramma the left ventricle having the horseshoe or ovoid form depending on a position of its observation is visualized, at the same time areas of insufficient blood supply are accurately shown. With use as the indicator of a pyrophosphate of technetium ( 99m Tc) appeared an opportunity to visualize only the center of an acute necrosis that opens great opportunities for diagnosis of an acute heart attack, and also overseeing by its current. By means of scintillation gamma cameras, in addition to a myocardium, it is possible to investigate also the speed of a blood-groove in vessels of a brain, kidneys and other bodies, i.e. to carry out an isotope angiography. The advantage of a scintigraphic research is low beam loading on inspected.

Termografiya (or thermovision) — a method of obtaining visible images of objects on their infrared radiation. It is carried out by the line-by-line review of an object with definition of intensity of infrared radiation in each point. At researches K. the termografiya is useful to diagnosis of frustration peripheral To. (e.g., extremities, the head), caused by the different reasons (neurovascular, acute thrombosis of arteries and veins, an obliterating endarteritis, thrombophlebitis, etc.). The method is completely atraumatic, does not demand introduction to an organism of tools and drugs, is carried out beskontaktno (see. Termografiya ).

Methods of functional researches of blood circulation

Task funkts, researches K. fullestly decides direct measurements of pressure of blood and rate of volume flow of a blood-groove, or consumption of blood.

A direct manometriya — tonometry of blood directly in a vessel or the camera of heart where enter the catheter filled fiziol, solution transferring pressure to externally located sensor or the probe with the microsensor on the entered end (see. Catheterization of heart ). The method of a direct manometriya is widely used also for measurement of venous pressure, including the central venous pressure (see. Blood pressure ).

Old methods of measurement of a consumption of blood (by means of hours of Ludwig, Rein's termochas, rotameters, elektroterbinometr, differential manometers, etc.) demanded obligatory opening of a vessel and therefore a framework of their use was limited to an acute experiment. Creation of the electromagnetic and ultrasonic raskhodometr which are not demanding opening of a vessel gave the chance to extend a method on hron, experiments, and, above all to transfer it to a wedge, practice for a research of rate of volume flow of a blood-groove at patients during operations, in particular using artificial circulation.

Fig. 2. Scheme of measurement of rate of volume flow of a blood-groove by an electromagnetic method: the blood vessel is located in the pulsing magnetic field, at the movement of blood on a vessel synchronously with a pulsation of magnetic field the electromotive force (EMF) which amplitude of pulsations is proportional to rate of volume flow of a blood-groove through a vessel is generated; measuring amplitude of pulsations of EMF, determine the speed of a blood-groove; 1 — a blood vessel (in a section), 2 — electrodes for measurement of EMF, 3 — an exit of an electric signal on the amplifier, 4 — the poles of an electromagnet creating magnetic zero in which the blood vessel is placed, 5 — the terminal of connection of the generator of square-wave pulses of current, 6 — windings of excitement of an electromagnet, 7 — the core of an electromagnet.

The principle of an electromagnetic raskhodometriya (fig. 2) is based on the law of electromagnetic induction and is as follows. If the vessel to arrange between poles of a horseshoe magnet, then blood as the carrying-out environment, moving along a vessel, will cross magnetic field and to create the EMF which is directed perpendicular to magnetic field and the movement of blood. Size EMF is proportional to tension of the field and speed of the movement of blood in it. Measuring EMF, determine the speed of the movement of blood. As the perceiving link serves the sensor which is carried out in the form of not closed ring which is put on the explored site of a vessel.

The ultrasonic raskhodometriya is based on the following phenomenon: the ultrasonic beam directed along a moving flow of blood, being reflected from uniform elements, changes the frequency in proportion to the speed of movements of a flow of blood.

Fig. 3. Scheme of measurement of rate of volume flow of a blood-groove by an ultrasonic method: the ultrasonic beam sent by a radiator at an acute angle to a vessel, being reflected from moving uniform elements of blood, changes frequency and it is perceived by the receiver; change of frequency is proportional to the speed of a blood-groove; 1 — a wall of a blood vessel, 2 — the uniform element of blood moving in the direction of an arrow, 3 — an ultrasonic beam of a radiator, 4 — a radiator of ultrasound, 5 — the receiver of ultrasound accepting the reflected signals from uniform elements of blood, 6 — the reflected ultrasonic beam (shooters specified the direction of the movement of ultrasound and a uniform element).

Measuring change of frequency of the ultrasonic beam reflected by blood, define peripheral speed of the movement of blood. For measurement of rate of volume flow of a blood-groove the beam is directed at an angle to a flow that it crossed the layers moving with different peripheral speed (fig. 3). Definition of rate of volume flow of a blood-groove can be conducted this way both on an otpreparirovanny vessel, and through skin (with a body surface). The method allows to conduct a hemadromometry in deeply located vessels. However because of pulse movements of other vessels from which the ultrasonic beam is also reflected there can be errors in results of measurement. Reliability and accuracy of measurement depend also on the accuracy of the direction of a beam on a vessel. For measurement on a naked vessel the sensor is carried out in the form of not closed ring which is put on a vessel, on an inner surface to-rogo there is a piezoelectric transducer.

Fig. 4. The scheme of a hemadromometry the heated thermoresistor: the blood washing the thermoresistor which is continuously warmed up by electric current takes away from it heat; as intensity of heat removal is proportional to a flow rate of blood, temperature of the thermoresistor taken on its resistance reflects the speed of the movement of blood; 1 — a wall of a blood vessel, 2 — terminals of connection of the thermoresistor with the measuring device, 3 — a flow of the blood moving to the thermoresistor, 4 — the thermoresistor, 5 — a flow of the blood which is warmed up by the thermoresistor.

Rate of volume flow of the movement of blood can be determined by measurement of peripheral speed of a blood-groove with the subsequent multiplication of this size by the cross-sectional area of a vessel. For definition of instantaneous values of speed of a blood-groove use the method based on assessment of intensity of transfer of heat by a heated body to a moving fluid flow. For this purpose enter the body which is warmed up by electric current into a blood channel (e.g., the thermo-resistor) and on change of resistance register its temperature, edges are reflected by intensity of heat removal from the thermoresistor the proceeding blood and depends on the speed of its movement (fig. 4). Thus, the curve of change of resistance of the thermoresistor reflects process of change of speed of a blood-groove. The sensor of the measuring instrument of speed of blood represents the special probe entered into a circulatory bed, supplied with the converter comprising or combining heating and thermosensitive elements. The device represents the continuous measuring instrument of electric resistance.

Indirect methods. Daily the wedge, practice demands definition funkts, characteristics To. in the least traumatic ways. It defined search of indirect methods of discrete measurement of private indicators of blood pressure and the rate of volume flow of a blood-groove generally characterizing the level of functioning of cardiovascular system.

Indirect measurement of the ABP is carried out by squeezing of a vessel from the outside and tonometries at the moments when external pressure is equal systolic and diastolic. At the same time the main difficulty consists in establishment of reliable signs of exact equality of external and intravascular pressure. The most widespread is the auskultativny sign which is the cornerstone of measurement of the ABP on tones Korotkov. Also other signs are known; also other methods are based on them oscillographic, phase.

Determination of average pressure is also carried out in the compression way on condition of equality of the external and average ABP at the time of achievement of the maximum amplitude of pulsations of pressure in a compression cuff. On this basis the method and the device is developed for long continuous measurement of average pressure of blood (see. Blood pressure ).

Determination of minute volume of blood is carried out by means of the gas-analytical methods, dilution methods of the indicator and methods based on determination of systolic volume of heart.

From gas-analytical methods the oxygen method, or Fick's method based on determination of amount of the oxygen (in ml) absorbed by an organism in 1 min. and establishment of the oxygen content in an arterial and venous blood is most reliable:

MO = Q / (Ca - Cb),

where MO — the minute volume of blood, Q — oxygen absorption an organism (in ml/min.); Ca and Cb — concentration of oxygen respectively in arterial and venous (in a right ventricle or a pulmonary artery) blood (in ml/l).

The minute volume of blood can be determined also by release of carbon dioxide, and also by an arteriovenous difference for carbon dioxide. This method is technically simpler, but its accuracy depends on difficult achievable stability of external respiration.

Modifications in which about saturation of blood gases judge by structure of an alveolar air or by addition of certain amounts of alien gas (acetylene, nitrous oxide, etc.) to inhaled air are developed. These modifications were not widely adopted since possess big errors and have a number of contraindications to use.

The dilution methods of the indicator offered by Stewart and Hamilton (G. N. Stewart, W. F. Hamilton), are the most widespread methods of determination of minute volume of blood. As the indicator apply dyes (kardiogrin, Evans-blue, etc.) » the warmed-up or cooled isotonic solution of sodium chloride and some isotopes. The indicator is entered into the main vessel, and in any remote part of system (e.g., in a lobe of an ear) conduct continuous measurement of concentration of the indicator in blood, by data to-rogo determine the minute volume of blood.

There are methods using bystry (during 1 — 2 sec.) and slow continuous introduction of the indicator. The greatest distribution was gained by a method with bystry introduction of the colourful indicator. Modern methods allow to enter the indicator into an elbow vein, and to measure its concentration in blood by the photo-electric sensor in vessels of an auricle with continuous registration of a curve of cultivation. At the same time minute volume is determined by a formula:

MO = [J*60/S]*[100/(100=Ht)],

where J — the number of the entered indicator (in mg); S — the area of the main wave of a concentration curve expressed in mg • sec. / l-(concentration of the indicator in mg on 1 l of blood, time in seconds); Ht — a hematocrit. For determination of the area S final phase of the main wave is adjusted, extrapolating its descending branch a straight line, and for definition of a hematocrit and calibration of the photo-electric sensor from a vein take blood samples before administration of dye.

Devices in which almost all process of measurement is automated are developed. In such devices the measuring instrument — the special photo-electric sensor with two photosensitive cells, one of which is sensitive, another is insensitive to the indicator, impose on an auricle. The device is supplied with the compression device for desalination of fabric on site of imposing of the sensor. Taking measurements before introduction of the indicator in filled with blood and exsanguinated fabrics, the device by means of the built-in computer calculates concentration of the indicator in blood during its change. The bias in such devices does not exceed 3%.

Except the minute volume of blood determine by an indicator curve OTsK, time of a blood-groove from an injection site of the indicator to the place of its observation. OTsK determine by a formula:

OTsK = J/C, where J — the number of the entered indicator (in mg); With — concentration of the indicator at its full cultivation.

Simpler, but less exact method is the method of measurement of time of a blood-groove, a cut is defined as a time slice, during to-rogo any indicator entered into a blood flow passes from the place of its introduction to a point of observation. As physical indicators use flyuorestsein which is entered into an elbow vein of one hand and define its existence in a vein of other hand, radioisotopes 185Cr, 24Na, 131I which find by method of radio indication, etc. Magnesium sulfate, calcium chloride, a histamine, ether, lobeline which speed of advance in a circulatory bed is found on time of approach fiziol, reactions are among biologically active agents: feeling of heat in a mouth, a hyperemia of the person, a smell in expired air, a tussive reflex etc. Using various indicators, define time of a blood-groove on different pieces of a circulatory bed, on the Crimea reveal area and degree of developments of stagnation in system K. The value of definition of time of a blood-groove is limited to existence of contraindications to use of a number of indicators.

By a method of thermocultivation the dvukhprosvetny probe, in one channel to-rogo there pass wires to the thermo-resistor mounted on the entered end of the probe carry out through the right heart to a pulmonary artery. On the second channel enter the cold indicator into the right auricle — isotonic solution of sodium chloride of room temperature and by means of the thermoresistor which is in a pulmonary artery register the curve of change of local temperature reflecting cultivation of the indicator. At bystry introduction of the indicator the minute volume of blood (in l/min) is determined by a formula:

MO = 0,06*vi * (the TT - Ti) / S,

where MO — the minute volume of blood, an indicator 0,06 — coefficient of recalculation; Vi — the number of the entered indicator (in ml), the TT and Ti — body temperature and the indicator, S — the area of the main wave of a curve of cultivation (during a hail sec.).

The main advantage of a method — lack of effect of accumulation of the indicator in blood and a possibility of repeated repeated measurements; shortcomings — need of catheterization of heart, an error of determination of temperature of the indicator for an injection site, heating of the indicator owing to a supply of heat from tissues of heart.

Determination of systolic volume of heart. Sfigmografichesky methods are based that emission of blood in arterial system causes its systolic filling and proportional increase in the ABP with diastolic to systolic level.

Several ways of calculation of systolic volume of heart according to measurement of pulse pressure and rate of propagation of pulse wave in an aorta with definition according to tables of cross-sectional area of an aorta are offered. On Bremzera and the Wound (P. Broemser, O. of Ranke, 1930),

CO = (1333 • Q • ΔР • Z • T • Tc) / (ρ • α • Td),

an on Vetslera and Begera (To. Wezler, A. Boeger, 1937)

CO = (1333 • Q • ΔP • T) / (2ρα),

where WITH — the systolic volume of heart, Q — the cross-sectional area of an aorta (in cm 2 ); ΔP — pulse pressure (in mm of mercury.); ρ — density of blood (in g/cm 3 ); usually ρ = 1,06 g/cm 3  ; α — rate of propagation of pulse wave (in cm/sec.); The CU — duration of exile (in sec.); T — duration of a cardial cycle (in sec.) Td = T — the CU; Z — a correction factor; Z = 0,48 - 0,6; T' — the period of the main fluctuation in the sphygmogram of a femoral artery in sec.; 1333 — coefficient of recalculation.

Considerable discrepancy (to 25%) results of measurement by these methods with data of measurements on Fick and Stewart's methods — Hamiltona led to the fact that sfigmometrichesky methods began to be applied less often.

Reografichesky methods are based on measurement of a full electric impedance of a body in the field of an arrangement of heart (see. Reografiya ). As the electric resistance of a body depends on a krovenapolneniye of the structures which are in a measuring chain (see. Conductivity of biological systems ), measurement of the sizes of heart during a cardial cycle can be registered reografichesk, the most exact results receive by means of tetrapolar reografichesky measurement of systolic volume of heart. By this method around a neck and a trunk at the level of a xiphoidal shoot impose two tape electrodes in pairs fastened in the form of belts. On couple of the external electrodes, most remote from heart (one on a neck, the second on a torso) give alternating current of constant intensity and on power failure on the second (internal) couple of electrodes continuously measure resistance between them. The systolic volume of heart is determined by a formula:

WITH = ρ (L/Z0) of T(dz/dt),

where ρ — the specific resistivity of blood (usually 135 ohms-cm); L — average distance between internal couple of electrodes (in cm); T — time of reduction of ventricles (in sec.); Z0 — an average value of an impedance of a body between couple of internal electrodes (in ohm), (dz/dt) — the minimum value of speed of change of an impedance during a cardial cycle (in ohm/sec.). Lack of a method is indirect communication of a volume krovenapolneniye of heart with the electric resistance of a thorax, and also incomplete compliance of changes of volume of heart to systolic volume. Therefore the method cannot apply for high precision of absolute measurements. However its simplicity, suitability for long measurements and accuracy of assessment of relative changes of systolic volume of heart put it in number of perspective methods of a dynamic research.

X-ray diffraction techniques are based on calculation of systolic and diastolic volumes of cameras of heart by the sizes of projections of a shadow of heart or its cameras on x-ray films. The most precisely systolic volume of heart decides at contrast researches of a left ventricle in two mutually perpendicular planes on cardiosynchronized shooting at the end of a systole and a diastole (see. Heart, methods of a research ).

Definition of some complex characteristics of the blood circulatory system. Along with quantitative values of rate of volume flow of a blood-groove and blood pressure great value in assessment of function of system K. and its parts have derivatives of size from them — cardiac index, work of ventricles of heart, peripheric resistance of a vascular bed.

Cardiac index characterizes the average level of blood supply of body tissues, at the same time communication of intensity of a blood-groove with the sizes of an organism is considered:

The SI = MO/FRIDAY,

where the SI — cardiac index (in l / min-m 2 ); MO — the minute volume of blood (in l/min); FRIDAY — a body surface (in m 2 ). Normal cardiac index is rather stable characteristic and for the healthy person at rest; according to Dexter (L. Dexter, 1947), it makes 3,12 l / mi N • m 2 .

Hydraulic resistance of a vascular bed is defined by the relation of pressure drop on a source of resistance to rate of volume flow. The main resistance to a blood-groove is shown by small peripheral arteries. At the movement of blood on a big circle To. the general peripheric resistance is expressed by a formula:

OPS = 8*10 4 (Ra - Rv) / MO of di of N • sec./cm 5

or

OPS = 0,8 (Ra - Rv) / MO N with/cm 5 ,

where OPS — the general peripheric resistance; Pa and Rv — respectively average arterial and central venous pressure (in mm of mercury.), MO — the minute volume of blood (in l/min).

In the same way determine the general peripheric resistance of a small circle of K. Razlichiye consists only in values of sizes of Ra and Rv which in this case will designate respectively the average pulmonary pressure and average pressure in pulmonary veins.

Fig. 5. Chart of work of a ventricle of heart. Phases of work of a ventricle: 1 — 2 — isometric contraction; 2 — 3 — exile of blood; 3 — 4 — isometric relaxation; 4 — 1 — filling; To TO — konechnodiastolichesky volume; KSO — konechnosistolichesky volume; Rs — systolic pressure; Rs — average systolic pressure; Rd — diastolic pressure; Rd — average diastolic pressure. The work made by a ventricle during a sphygmic interval corresponds to the area of a figure 6 — 1 — 2 — 3 — 4 — 5 or the areas equal to it a rectangle 6 — 2' — 3' — 5: the work spent for filling of a ventricle with blood corresponds to the area of a figure 6 — 1 — 4 — 5. The area of the rectangle limited from above and from below to dashed lines corresponds to shock work of a ventricle.

Definition of the power characteristic of heart. The mechanical cardiac performance spent for movement of blood is defined by dependence:

And = ∫P(t) dV,

where And — mechanical cardiac performance; P(t) — pressure created by work of a ventricle of heart; dV — the moved volume of blood for a unit of time. Calculation of the work made by a ventricle of heart with use of this dependence can be executed according to the chart of cardiac performance, on a cut process of change of pressure in a ventricle and its volume is presented during reduction and filling (fig. 5). The work made by a ventricle in the course of reduction is represented of I (fig. 5, points 6, 2, 3, 5), II Square corresponds to the work spent by the arriving blood and an auricle for filling of a ventricle (fig. 5, a point 6, i, 4, 5). Shock work of a ventricle will correspond to a difference of the areas of I and II. Thus, the chart of cardiac performance characterizes the work not only made by a ventricle but also the work spent for its stretching and filling. For creation of the chart it is necessary to have instantaneous values of chamber pressure and its volume during all cycle. But also in this case definition of work of a ventricle is extremely labor-consuming. Therefore for practical purposes use the simplified representation, believing that pressure in a ventricle during exile is invariable also to equally average systolic value (Rs). Then shock work of a ventricle will correspond to the area of the rectangle limited from above and from below to dashed lines, and to be expressed quantitatively by approximate dependence:

And = 1,333*10 - 4 (Rs - Rd) WITH, where And — external work of a ventricle (in J), Rs and Rd — an average during exile systolic and final diastolic pressure in a ventricle (in mm of mercury.), WITH — the systolic volume of heart (in ml).

For definition of work of a left ventricle of Rs pressure can accept equal to an average during exile in an aorta, and Rd — equal 5 mm of mercury. During the definition of work of a right ventricle of Rs accept equal to an average during exile to pressure in a right ventricle or a pulmonary artery, and Rd equal final diastolic' to pressure in a right ventricle or the right auricle.

The average power (W) developed by a ventricle can be determined by a formula:

W = (A*ChSS)/60,

or

W = 2,22 • 10 - 3 (Rs - Rd) MO,

where W — the power, average for a cycle, developed by a ventricle (in W); ChSS — the heart rate (beats/min). Value of power is frequent carry to the surface area of a body. This indicator can be called specific power. The size of the specific power of a ventricle (W) specified to a surface unit of a body is determined by a formula:

W' = 2,22 • 10 - 3 (Rs - Rd) the SI,

where W' — specific power (in W/m 2 ); The SI — cardiac index (in l / min-m 2 ).

Research of the temporary organization of the cardiohemodynamic phenomena. Cardiohemodynamic processes happen in a certain temporary sequence. Defining these time frames of the current processes, it is possible to gain an indirect impression about the dynamic organization K. and its disturbances.

There is a number of the methodical directions according to temporary funkts, characteristics of cardiovascular system: the analysis of a rhythm of cardiac performance, the analysis of the temporary organization of hemodynamic processes in heart during a cardial cycle or phase operational analysis of heart, the analysis of the temporary sequence of the pulse phenomena in an organism determined by rate of propagation of pulse waves (see. Pulse ).

The analysis of a rhythm of cardiac performance — a widespread method of a research of action of the heart, in the course to-rogo is defined duration of a cardial cycle or the return by it size — heart rate, and also them fiziol, and patol, fluctuations. Usually electrocardiosignal (QRS complex) which starts intervalometr — the measuring instrument of duration of a cardial cycle, or a cardiotachometer — the measuring instrument of heart rate is the main source of information. Similar measurements can be carried out also pulsotakhometry on the basis of perception of the pulse signal removed by usually photo-electric sensor from a finger of a hand. A number of programs and devices for the analysis of regular and arrhythmic pulse is known. The monitors of arrhythmia intended for early identification of frustration of a cordial rhythm in system of intensive overseeing by patients are among the last (see. Monitor observation ).

The phase analysis — the method of definition of temporary structure of a cardial cycle used for quantitative assessment funkts, conditions of heart and the central K. Razlichayut direct and indirect methods of the phase analysis (see. Polikardiografiya ). The direct method is based on single-step record of indicators of pressure in cardial cavities and the central vessels and their correlation with an ECG. The method has high precision. The indirect method is based on synchronous record ECG, FKG and sphygmograms of a carotid artery. Unlike the direct method demanding catheterization, this method is completely atraumatic thanks to what it found broad application in a wedge, practice.

Methods of assessment of dynamic changes of a krovenapolneniye: overseeing by fluctuations in a krovenapolneniya of vessels is carried out by methods pletizmografiya (see), reografiya (see), and also an arterial and venous pulsografiya (see. Pulse , Sfigmografiya ).

Other methods of a research

Complexity of approaches to direct measurement of the main characteristics To. caused development of methods in which information on secondary — not hemodynamic phenomena accompanying propulsive function of heart is used. Mechanical movements and vibrations of parts of cardiovascular system and adjacent structures concern to them: the movements of precardiac area of a thorax (see. Dinamokardiografiya , Cardiography , Kinetokardiografiya , Seysmokardiografiya , Fonokardiografiya ), air pulsations in respiratory tract, synchronous with action of the heart, the pulsations transmitted through a wall of a gullet (see. Ezofagokardiografiya ), the reactive movements of a body (see. Ballistokardiografiya ). Registration of the nonmechanical secondary phenomena is methodically convenient: changes of electric resistance of fabrics (see. Reografiya ), their optical density — a fotopletizmografiya (see. Pletizmografiya ). Indirect character of these methods does not reduce high informational content.

Feature of methods of all this group — expression of a result in not hemodynamic, and in the phenomenological concepts answering to physical essence of the registered phenomena (movements of heart, acoustic noise and tones, electric resistance, etc.). Many of them entered daily use of specialists, are perceived and analyzed as specific hemodynamic data.

Along with the considered methods of a research central and peripheral To. there are special methods of a research capillary and regional To.

See also Blood circulation regional .



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T. 3. Meerson, H. A. Barbarash; V. A. Bogoslovsky (cards.), O. V. Korkushko (geront.), E. K. Lukyanov, V. S. Salmonovich (tekhn.), G. I. Mchedlishvili (stalemate. physical.), E. V. Neudakhin (ped.).

Яндекс.Метрика