Study of the cardiovascular system in animals. Study of the arterial pulse of animals. Examination of the circulatory organs of dogs and cats

Percussion of the heart area is one of the most difficult diagnostic tasks. It is carried out to determine the boundaries of the heart, by which one can get an idea of ​​its size, shape and position in the chest, as well as to establish the sensitivity of the heart and the nature of the percussion sound.

Percussion is carried out with the front limb maximally retracted; in large animals, mediocre instrumental percussion is more often used, in small animals, mediocre digital percussion.

The heart adjoins the chest wall only partially, since it is covered by the pulmonary edges along the periphery. By percussing the region of the heart from top to bottom along the intercostal spaces, one can catch the transition of a clear pulmonary sound into a dull one, then into a dull one. The area of ​​the heart adjacent to the chest wall gives a dull sound (the zone of absolute dullness of the heart), and the area covered by the lungs gives a dull sound (the zone of relative dullness of the heart).

The boundaries of relative cardiac dullness correspond to the projection of the surface of the heart on the chest and are the true boundaries of the heart.

Absolute dullness is normally recorded in horses, foxes, dogs; in most other animals it is not found, since the cardiac notch is easily covered by a thick layer of muscles of the pectoral girdle.

Method of percussion of the heart.

In large animals, percussion of the heart area is performed using a percussion hammer and a plessimeter (instrumental percussion) in the conventional way, while in small animals it is more convenient to percussion with fingers (digital percussion). The percussion borders of the heart are determined on the left, and in the diagnosis of right ventricular hypertrophy, pericarditis and other indications, right-sided percussion is also performed. The boundaries of relative dullness are better recognized with stronger percussion, and absolute, on the contrary, at the threshold of auditory perception ("threshold percussion"). Percussion is carried out with the animal standing; percuss the region of the heart in two directions:

1) along the back vertical line of anconsus;

2) from the ulnar tubercle to the maklok.

The researcher should be on the side on which the percussion is performed. Auditory perception is carried out at the level of occurrence of percussion sounds. In large animals, the corresponding thoracic limb is set aside, bent at the carpal joint and pulled forward. In cattle and one-hoofed animals, only the dorsal and caudal boundaries of cardiac dullness can be accurately established, while in carnivores, the part of the cardiac region covered with the sternum is also percussed (when the animal is sitting).

At a large cattle the zone of dullness of the heart is weakly expressed and is located in the subscapular region at the apex of the angle formed by a vertical line going to the head of the ulnar tubercle and a line inclined to it, going at an angle of 45°. Percussion is difficult even with strong abduction of the limb. Relative dullness of the heart on the left is percussed in the 3rd-4th intercostal space. Its upper border reaches the line of the shoulder joint, and the back reaches the 5th rib. The lower percussion border of the heart coincides with the dullness formed by sternum. In the 3rd intercostal space, this dullness is recognized only when the left thoracic limb is pulled forward, and in the 4th intercostal space, on the contrary, it is more accessible to research. On the right percussion sound of dullness is not detected.

In sheep and goats, three borders of dullness of the heart are established: anterior, in the 3rd intercostal space; back - up to the 5th rib; upper - 1-2 cm below the line of the scapular-shoulder joint. Relative dullness of the heart is found only in the 3rd-4th intercostal space from the midline of the sternum to the middle of the lower third of the chest. On the right, normal percussion does not give results.

In horses and other one-hoofed animals, 3/5 of the heart is located in the left half of the chest cavity, and its apex is in the 5th intercostal space 2 cm above the upper border of the sternum. On the left, in the region of the 4th-5th ribs, it is in the form of a triangle adjacent to the chest wall, creating a zone of dullness. The upper limit of the relative dullness of the heart normally passes in the 3rd intercostal space on the left, 2-3 cm below the line of the scapular-shoulder joint, and the posterior one reaches the 6th rib. The area of ​​absolute dullness of the heart has the shape of a triangle, its anterior border goes along the line of the anconeus, the posterior border goes from top to bottom and goes arcuately from the 3rd intercostal space to the lower edge of the 6th rib, and the bottom one passes without a sharp border into dullness sternum and its muscles. The height of the triangle in the 3rd intercostal space is 10-13 cm, depending on the size of the animal. The area of ​​absolute dullness on the right is much smaller and occupies the most lower part 3rd and 4th intercostal space. The area of ​​relative cardiac dullness, both on the left and on the right, goes in the form of a strip 3-5 cm wide, surrounding the absolute dullness of the heart.

In pigs, the upper limit of the relative dullness of the heart reaches the level of the shoulder joint, and the posterior limit, up to the 5th rib. In animals of good fatness, percussion does not always give positive results.

In carnivores, percussion of the cardiac region is carried out along three boundaries:

1) anterior - along the anterior edge of the 3rd rib;

2) upper - 2-3 cm below the scapular-shoulder joint;

3) back - up to the 7th rib.

Absolute dullness of the heart is found in the 4-6th intercostal space. Its anterior border starts from the middle of the sternum parallel to the caudal edge of the 4th rib, goes vertically to the costal symphyses, and the dorsal border goes horizontally in the 4th-5th intercostal space and reaches the 6th intercostal space, forming a curved back curve. Caudally, without a sharp border, it passes into the zone of hepatic blunting, and from the midline of the sternum, into right-sided cardiac blunting in the 4th or 5th intercostal space 1-2 cm dorsally top edge chest bone. In this case, one merging zone of blunting is formed in the ventral area. chest well defined in dogs in their sitting position.

The boundaries of cardiac dullness can also be set by percussion along arcuate curves, approaching the boundaries from the periphery, as well as along the intercostal spaces.

The change in the boundaries of cardiac dullness depends on the size of the heart and the nature of pathological changes in the pericardial sac and lungs. Thus, with an increase in the volume of the heart, for example, with its expansion and hypertrophy, the boundaries of relative and absolute dullness shift, and with an increase in individual parts of the heart, the configuration of the heart area changes. dullness. So, in the case of an increase in only the left ventricle, its posterior border shifts in the lower part of the area of ​​​​cardiac dullness, then only the atria - its posterior border shifts in the upper part of the area of ​​​​cardiac dullness, the right ventricle - the area of ​​\u200b\u200bdullness on the right side increases, etc.

The accumulation of fluid in the cavity of the pericardial sac leads to the displacement of the edges of the lungs from the surface of the heart, as a result of which an area of ​​​​absolute dullness appears or increases, its boundaries shift up and back.

The displacement of the boundaries of the area of ​​cardiac dullness occurs in the same cases as the displacement of the cardiac impulse.

Tympanic sound in the region of the heart occurs with traumatic pericarditis as a result of the formation of gases in the pericardial shirt, with fibrinous pneumonia in the stage of hyperemia, pneumothorax.

Pain on percussion in the region of the heart is observed with inflammatory processes in tissues chest wall, pleurisy, pericarditis, etc.

Percussion of the heart is considered one of the most difficult tasks clinical diagnostics. Situated deep in chest cavity the heart directly adjoins the chest only partially, for the most part it is covered by the edges of the lung. By contrast between a clear pulmonary sound and dullness, from the side of the heart, one can judge the position, size and configuration, especially in cases of significant increase in pathological conditions. Distinguish twofold cordial dullness. The part of the heart immediately adjacent to the chest gives a dull sound. The dull sound zone is much smaller than the true contour of the heart, but changes in it during pathology can be used to judge changes in the heart itself. The part of the heart covered by the lungs gives a dull sound on percussion. This zone, which gives an idea of ​​the true size of the heart in small animals, is called relative cardiac dullness. The zone of relative cardiac dullness passes in large animals without a pronounced border into an atympanic sound of the lungs.

Absolute heart failure. The definition of absolute cardiac dullness is made either by percussion from the periphery to the heart or, conversely, from the heart to the periphery. In the first case, the boundaries are defined along arcuate lines, starting from the point of intersection of the line of the scapular-shoulder joint with the line of the anconeus group.

The first arcuate curve ends in the eighth intercostal space, giving an atympanic sound throughout. The second, the same arc-shaped, curve is drawn 2 cm away from the first towards the heart. According to this curve, the sound is weaker and quieter. As you approach the zone of absolute dullness, the sound becomes more and more dull. The border between dullness and dullness is marked with dots and then connected with a line. Absolute cardiac dullness makes itself felt by means of a very quiet or dull sound. It must be borne in mind that in its upper part the zone of absolute dullness does not give an absolutely dull sound, but a dull sound with a tympanic tint. The tympanic shade depends on the proximity of the lung covering part of the heart.

It is also possible to determine the boundaries of absolute dullness from the heart to the periphery. In this case, the absolute dullness of the heart is first determined, and then relative dullness is determined from it by percussion to the periphery with the transition to an atympanic sound of the lung. In this case, the upper and posterior borders of the heart are determined.

V. P. Sidorov recommended following method defining the boundaries of the heart. The upper limit is determined by an oblique line running from the posterior angle of the scapula down near the anconeus, with the left thoracic limb as far forward as possible. Along this line, the upper border of the heart is 2-3 cm below the horizontal line drawn along the scapular-shoulder joint, and in cattle, on this line. The posterior border is determined by an oblique line running from the maklok to the middle of the area of ​​absolute dullness. The posterior border of the heart in the horse reaches the sixth rib, and in cattle it reaches the fifth rib. The transition of an atympanic sound to a dull, distinct sound.

To determine the absolute dullness of the heart, mediocre percussion is used in large animals and direct in small ones. The definition of boundaries is best achieved with percussion of the lung, with a delay of the percussion hammer on the plessimeter. It must be borne in mind that by means of weak percussion one can achieve much best results than with a strong one. In a horse, the area of ​​absolute dullness has the shape of a versatile triangle, located in the region of the 3rd-5th intercostal space on the left. Starting in the third intercostal space, from the posterior edge of the anconeus muscle group, at some distance from the line of the scapular-shoulder joint, it descends in a convex arc to the lower end of the sixth rib; below, the dullness of the heart passes into the absolute dullness of the sternum and its muscles. The height of the triangle in the third intercostal space ranges from 10-13 cm. These fluctuations depend on the size of the animal, the structure of the chest and the size of the heart. Thus, absolute dullness captures the lower part of the third, fourth and fifth intercostal spaces. The heart in this part touches the chest wall with the anteroinferior part of the left ventricle and the posterior inferior part of the right ventricle. The dullness on the right is much smaller in size and covers only the lowest part of the third and fourth intercostal spaces.

In dogs, absolute dullness is easily determined in the region of the 4th - 5th intercostal space, in the upper part, and the sixth intercostal space in the lower, on the left side. Percussion can be done with a finger on a finger, using weak percussion when determining the boundaries.

Increased area of ​​cardiac dullness. The reason for the increase in the zone of absolute dullness may be hypertrophy of the heart muscle, expansion of the heart and the presence of exudate and transudate in the pericardial sac. Less often, an increase in absolute dullness is possible with compaction of the edges of the lung covering the heart. Depending on whether the whole heart or any part of it increases, an increase in cardiac dullness is noted in one direction or in several.

In all directions, cardiac dullness increases with accumulation large quantities inflammatory or edematous fluid in the pericardial cavity (pericarditis, hydropericarditis). An increase to the left is noted with left ventricular hypertrophy and its expansion.

Decrease in cardiac dullness. Decrease in cardiac dullness is not associated FROM Decreases in the size of the heart and depends mainly on the cover heart lungs. A decrease in the area of ​​cardiac dullness is established in acute, and sometimes in chronic forms alveolar emphysema. An emphysematous lung pushes the heart away from the chest wall, which leads to a decrease, and sometimes the complete disappearance of a dull sound, which is replaced by relative dullness.

Displacement of absolute dullness of the heart. The displacement of cardiac dullness is due to the movement of the heart in the chest cavity and is noted in the same cases as changes in cardiac impulse.

Relative cardiac dullness. In areas where the heart is covered by lung tissue, percussion reveals dullness, which passes from the zone of absolute dullness without a pronounced border into the atympanic sound of a normal lung. Percussion of relative cardiac dullness is difficult and requires known skill. In medicine, the best method, which gives less subjectivity, is the Golypreider method and other methods close to it, which allow percussion to be performed at the threshold of perception. Direct percussion in this case is good because it allows you to perceive sound and tactile impressions.

In the horse, the zone of relative dullness, both on the right and on the left, is in the form of a strip 3-5 cm wide, surrounding absolute dullness.

In cattle, the heart is mostly covered by the lungs. Direct contact of the heart with the chest in the region of the cardiac notch is completely inaccessible to clinical trial, since this zone is located under the scapular-shoulder girdle. Relative cardiac dullness is found in the third and fourth intercostal spaces.

The appearance of an absolutely dull sound in the region of the heart in cattle is noted only with an increase in the size of the heart and is more often associated with traumatic pericarditis.

Tympanic percussion sound in the area of ​​cardiac dullness. With exudative pericarditis in the heart shirt is found a large number of exudate, causing an increase in the zone of absolute dullness. Above the exudate, as a result of the vital activity of putrefactive microorganisms, gases are formed that accumulate in the upper part of the cavity of the heart shirt. The presence of gases causes a high resonance sound, sometimes with a metallic tinge. The combination of tympanic sound with an increase in absolute dullness is most often observed in cattle and is one of the reliable symptoms of traumatic pericarditis.

The cause of the tympanic sound may also be infiltration lung tissue covering the heart. In adult pigs of good fatness, there can be no question of even an approximate definition of the boundaries of the heart.

Despite the difficulties of percussion of the heart in animals, the determination of the zone of absolute and relative dullness is of considerable diagnostic value. On the basis of percussion data, it seems possible to judge the size of the heart, its location and changes occurring in the heart shirt. The effectiveness of the method depends both on the method of percussion and on the practical skills of the specialist.

The heart and circulatory system of cats.

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Additional Information:
Heart disease in cats
Congenital and hereditary diseases hearts
Cardiomyopathy
Acquired diseases
Heart failure
Blood clots and aneurysms
Murmurs in the heart

The cardiovascular system of cats includes the heart itself and blood vessels - veins and arteries.

Structure of a cat's heart.

Heart acts as a pump - pumps blood. The right side of the heart pumps blood to the cat's lungs, where oxygenation takes place. Left-hand side serves the rest of the organs, delivering blood and nutrients to them, as well as removing the "waste" of vital activity (such as, for example, carbon dioxide). The heart of a cat is a hollow muscular organ, which (like all mammals and birds) is divided into four chambers. The muscular middle layer of the heart is called the myocardium. The upper chambers of the left and right sides of the heart are called the atria (left and right, respectively). Both lower chambers are called ventricles - also left and right.

Work of cardio-vascular system cats.

A set of valves allows blood to flow through the cat's heart in the right direction. Atrioventricular valves are located between the atria and ventricles of the heart. The semilunar valves are located at the outlet of the aorta and pulmonary artery from the ventricles of the heart. Each ventricle of the heart has an inlet and outlet valve. In the left ventricle, the inlet valve is called the mitral valve and the outlet valve is called the aortic valve. In the right ventricle, the inlet valve is called the tricuspid valve and the outlet valve is called the pulmonary valve.

Blood from the body goes to right atrium through two large veins called vena cava.

When the right valve is open, blood flows into the right ventricle through the tricuspid valve. When the right ventricle is close to filling, the right atrium contracts, adding more blood to the right ventricle. The right ventricle itself then contracts, pushing blood through the pulmonary valve into the pulmonary artery, which leads to the cat's lungs. In the lungs, blood absorbs oxygen and releases carbon dioxide. After that, blood through the pulmonary veins into the left atrium.

When the right valve is open, blood enters the left atrium through mitral valve left ventricle. After the left ventricle becomes nearly full, the left atrium contracts and more blood enters the left ventricle. The left ventricle then contracts, pushing blood through the aortic valve into the aorta. largest artery in the body of a cat. This blood carries oxygen through the aorta throughout the body, except for the lungs.

The work of the cat's heart.

Each contraction of the heart occurs in two stages - diastole and systole. The first stage is diastole, which can be tracked by the sound of closing of the mitral and tricuspid valves. The second stage - systole, is determined by the sound of the closing of the aortic and pulmonary valves. During diastole, the ventricles relax and fill with blood, and during systole, they contract and expel blood.

The rate and force of heart contractions, as well as the degree of filling of the constriction or expansion of blood vessels, are controlled by certain hormones and the autonomic nervous system (part nervous system which controls unconscious activity).

Heartbeat.

A cat's heart beats because it receives very small electrical impulses from the sinus (or sinoatrial) node. This node for the heart is a natural pacemaker. Periodic electrical impulses or discharges from the sinus node cause contraction of the fibers of the muscle tissues of the heart. As long as the cat is at rest, sinus node continues its work, issuing discharges - for a relaxed cat normal frequency is about 200 discharges per minute.

Heart rate is inversely related to blood pressure. When the pressure rises, the rhythm slows down, and when it falls, the pulse frequency increases.

Sounds and noises of the heart of cats.

The heart produces sounds due to the acceleration and deceleration of the flow of circulating blood, causing vibrations in the heart. Heart sounds can be heard with a stethoscope. Normally, two heart sounds can be distinguished in cats.

Heart murmurs are vibrations that can be heard in the heart or large blood vessels. Vibrations are typically caused by turbulences in the bloodstream or structures of the heart such as parts of the valves. Noises are generally described by temporal characteristics (that is, whether they are heard continuously or only intermittently), their intensity (that is, whether they can be heard easily or with difficulty), and by the location of their source. Not all murmurs are signs of cardiac dysfunction, for example, murmurs can almost always be heard in the heart of kittens up to six months of age.

arrhythmias in cats.

Arrhythmia is a violation of the heart rate, regularity or correct form heartbeat. Arrhythmia does not always indicate problems with the cat's heart. Many types of arrhythmia have no functional significance and do not require special treatment. Some types of arrhythmia, however, can cause severe consequences such as loss of consciousness due to lack of blood flow to the brain, or even lead to sudden death cats. Many diseases are associated with disturbances in the normal rhythm of the heart.

Pulse of cats.

Pulse is a rhythmic expansion of the arteries that can be felt with the fingertips during a physical examination of the cat. In a cat, the pulse is usually checked in the thigh (femoral artery). At healthy cat you can feel the pulse in the neck in the jugular cavity. The pulse may be absent, increased or weakened - all of which may indicate a certain type of heart disease or defect.

HEART POSITION

The longitudinal axis of the heart in a dog forms an open cranial angle of 40° with the sternum, in a cat it forms an angle of 25–30°, with the apex of the heart directed towards the diaphragm. The base of the dog's heart is oriented cranio-dorsally and lies approximately at the level of the 4th rib. The right (“cranial”) ventricular edge runs along the sternum, from which it is a short distance away, the left (“caudal”) ventricular edge follows the cranial edge of the VII rib. Both edges meet at the apex of the heart, which faces slightly to the left and reaches approximately the 7th costal cartilage. Thus, the heart is located 4/7 to the left and 3/7 to the right of the midline and occupies in this plane the space of the III-VI intercostal spaces, and in the frontal plane the space between the sternum and the middle of the chest cavity. Close to the chest wall, the heart is adjacent only to its left surface in the region of the cardiac notch of the left lung.

The topography of the lateral chest wall is important in such methods of clinical examination of the heart as palpation, percussion, auscultation, and radiography. The chest in its cranial part is closed by the scapula and part humerus and their associated muscles. The line of the triceps muscle, linea musculi tricipitis, is formed by the caudal border of the triceps muscle of the shoulder and stretches from the thoracic angle of the scapula to the ulnar tubercle. This line is clearly visible through the skin. By pulling the thoracic limb forward, the lateral chest wall in the region of the IV-VII ribs can be released for examination.

Rice. 3. The position of the heart in a standing dog fixed in formalin (according to Schummer, 1984)

A vertebra cervicalis VII; In vertebra thoracica I; With vertebra thoracica VI; D costa I; E costa VI; F scapula; G humerus; H sternum; I radius; To ulna

auricula cordis dextra, b conus arteriosus; with atrium sinistrum ef auricula cordis sinistra; d sulcus coronarius; e sulcus interventricularis paraconalis; f ventriculus dexter, g his margo ventricularis dexter; h ventriculus sinister, i its margo ventricularis sinister; k apex cordis; l Diaphragm contour

1 truncus pulmonalis; 2 arcus aortae; 3 aorta thoracica with aa. intercostales dorsales; 4 v. cava cranialis; 5v. cava caudalis; 6 a. pulmonalis sinistra, 6" vv. pulmonales; 7 ligamentum arteriosum (Botalli); 8 a. subclavia sinistra; 9 truncus brachiocephalicus; 10 a. subclavia dextra; 11a. carotis communis dextra; 12 a. carotis communis sinistra; 13 a. vertebralis; 14 v. jugularis externa sinistra 15 a. et v. axillaris sinistra, 15" a. et v. thoracica interna; the dashed line corresponds to the caudal margin m. triceps brachii (linea mi. tricipitis or anconaea)

Knowledge of the topography of the heart allows you to apply various methods lifetime diagnosis of the heart.

The apex beat of the heart, which occurs as a result of contraction of the heart muscle and leads to concussion of the lateral chest wall, in the dog is heard clearly on the left in the lower third in the IV-VI intercostal space, especially good in the V intercostal space, and slightly worse on the right in the IV-V intercostal space .

With the help of percussion, as a rule, it is possible to detect an area of ​​absolute cardiac dullness in the uncovered lung part of the heart on both sides in the IV-VI intercostal space. The dorsal border of this area is formed by the symphyses of the IV-V ribs. Auscultation of heart sounds or pathologically altered heart murmurs in a dog should be performed in the 5th intercostal space for the left ventricle and in the 4th intercostal space for the right ventricle. For intracardiac injection, only the right ventricle is suitable and the needle should be inserted from the right side into the 5th intercostal space as close as possible to the sternum.

In a cat, the caudal edge of the triceps muscle of the shoulder runs parallel to the IV intercostal space, the heart is located closest to the chest walls on the left side between the IV and VI ribs, on the right side - under the V rib. In these places, the apex beat of the heart is clearly perceived and heart sounds are well heard. The 5th intercostal space is also suitable for intracardiac injection in cats. At standing cat this point is directly above the ulnar tubercle.

R HEART DIMENSIONS AND MASS IN CARNIVORS

Tab. 1. Heart mass in dogs of various breeds (according to Ballmer, 1937)

FROM TRIPPING OF THE HEART WALL

The wall of the heart consists of three layers: epicardium, epicardium, myocardium, myocardium, and endocardium, endocardium.

The epicardium corresponds to the visceral plate of the serous pericardium. It covers the surface of the heart with a smooth, shiny, transparent shell. The outer layer of the epicardium consists of mesothelium, the cells of which, depending on the degree of distension of the heart, have a flat or cubic shape. Beneath them is the lamina propria, in which bundles of collagen fibers are arranged to follow changes in the shape of the heart. This is followed by a subepicardial layer of collagen and elastic fibers associated with the connective tissue backbone of the cardiac muscles. Large vessels and nerves pass through this layer. In the coronal sulcus and in areas of the interventricular sulci close to the base of the heart, there are deposits of adipose tissue, the amount of which depends on the age and fatness of the animal.

The red muscle layer, the myocardium, consists of membrane-covered longitudinal muscle cells of a special structure with a nucleus located in the center. Individual cells are connected to each other by means of processes extending at acute angles and form a kind of network. Adhesion lines, or insertion plates, disci intercalares, unite muscle cells into more extended systems of fibers covered with sarcolemma, sarcolemma. Those, in turn, form bundles, combined into a three-dimensional mesh, the cells of which are filled with delicate connective tissue - endomysium, endomisium. This internal connective tissue of the myocardium in some places continues into the collagen fibers of the tendons of the nipple muscles, connects the muscle fibers of the nipple muscles with the tendon strings of the valve valves. Quantity blood capillaries in the myocardium approximately corresponds to the number of muscle fibers.

The endocardium is a membrane of connective tissue and elastic fibers and a layer of endothelium lining internal cavities hearts and valves. The endocardium is movably connected to the base, which allows it to adapt to changes in the stretching of the walls during cardiac activity.

Auscultation of the heart occupies the first place among research methods, as it makes it possible to most fully study the sound phenomena associated with the work of a healthy and diseased heart. Both indirect and direct auscultation can be used to listen to the heart. Direct auscultation is carried out with the right ear, which is firmly applied to the chest wall in the area behind the elbow. In restless horses, it is better to listen with the left ear, which is applied to the posterior edge of the anconeus muscle group. The auscultation zone can be significantly expanded if the animal's left front leg is slightly forward. It must be taken into account that prolonged standing tires the animal, and it begins to worry. This creates extraneous rustles, which greatly complicate the study. Examination with the left ear in the region of the muscle group of the anconeus has the advantage that the animals stand still, and although the sounds are somewhat weaker than when the leg is abducted, the examination can be carried out without haste, without forced interruptions.

Mediocre auscultation with the help of a phonendoscope or soft stethoscopes is carried out in all cases to determine the points of the best audibility of heart tones, analyze their qualitative changes, to determine noise and in functional diagnostics. The advantage of mediocre auscultation is that it allows you to listen to animals in any position.

Heart sounds. When listening normal heart you can catch two rhythmically repeating sounds, which are called heart tones. They are short, have some musicality and resemble the clapping of a stretched fabric. Tones are separated from each other by pauses of various durations. The tone heard before a short pause coincides in time with the cardiac impulse and with the pulse. carotid artery, i.e. with ventricular systole, which is why it is called systolic, or first, tone. The tone that occurs after a short pause refers to the period of relaxation of the ventricles and is called diastolic, or second tone.

Heart sounds occur due to tissue tension during its work. Sounds are produced by tissues capable of vibratory vibrations. Such tissues include semilunar sail valves and fibrous orifices of the aorta and pulmonary artery. The contraction of muscle tissue gives sounds weaker, but longer than valves and fibrous holes.

Sounds that occur in various departments hearts merge into one common sound. The most powerful is the sound of the flap valves, which dominates the formation of tone and gives it a peculiar shade.

The first, or systolic, tone is of particular complexity in its origin. It consists of: a) bivalve and tricuspid tones, which contract simultaneously during ventricular systole; b) tones of stretchable connective tissue orifices of the aorta and pulmonary artery and c) muscle tones of contracting right and left ventricles of the heart. All these sound phenomena merge into the first tone. The diastolic, or second, tone is formed from two sounds that merge into one - the slamming of the valves of the aorta and pulmonary artery.

In pathological conditions, the change in tone depends on the qualitative changes in the individual components included in one or another tone, and therefore the ability to identify and isolate individual components allows you to establish the cause and localization of the process.

In humans, a third heart sound is also distinguished, which occurs at the beginning of diastole, i.e., in the proto-diastolic period. The origin of the third tone is based on the flow of blood into the empty ventricle from the atria with stretching of their relaxed wall (Gubergrits).

By the nature of the sound, both tones differ sharply from one another. The first tone is louder, much longer and stretched at the end; the second tone is shorter, higher and has a flapping character. The end of the second tone is abruptly cut off. Phonetically, the combination of the first and second tones can be represented as repeating syllables: boo-tup, boo-tup, boo-tup. Stress during auscultation in the fourth and fifth intercostal spaces falls on the first tone (chorea rhythm).

In large animals, the difference in sounds is so well expressed that the differentiation of tones in the norm, with relatively rare cardiac activity, is not difficult. In small animals with more accelerated work of the heart, you can use simultaneous listening and palpation. The systolic tone coincides with the heart beat. Simultaneous perception of tactile and auditory impressions can also be used in large animals with increased cardiac activity.

Differentiation of tones at normal operation heart helps, in addition, the difference in the pauses between the first and second tone and between the second and first tone. There is a short pause between the first and second tone, its duration is large dogs equals 0.2 seconds. The pause between the second and the first is 2 times longer and reaches 0.43 seconds in dogs. A kind of rhythm is created. The first tone follows a long pause, and the second tone follows a short one. At normal activities of the heart, all of the listed features in the work of the heart make it easy to distinguish heart tones from one another, to distinguish normal heart melody from pathological.

During febrile processes, the work of the heart is greatly accelerated. The shortening of the refractory period affects the duration of the intervals between tones, due to which the pauses become equal to one another. The nature of the tones changes, the differences between them are smoothed out, and they become similar to one another. To differentiate in these cases, it is necessary to use tactile and auditory perception. The first tone coincides with the heart beat.

Points of the best audibility of heart tones in (Punctum optimum). shortest distance from the heart opening - the source of sound - is called the projection of the openings of the heart, or the points of best audibility of heart sounds. The shortest distance is determined by the perpendicular restored from this hole to the surface of the chest. The intersection of the perpendicular with the surface of the chest wall will be the projection of this opening of the heart. The individual components that make up the first and second tones are formed in the lumen of the heart

Holes at some distance from one another. Naturally, the conduction of sounds to the chest in various points happens to be uneven. It depends both on the distance between the points of their formation, and on the point where auscultation is performed. The point where the intensity of the tone will be stronger, and the other valve similar to it is weaker, and is called the Punctum optimum of heart tones.

Determining the points of the best audibility of a tone is of great practical importance. In pathological conditions, it is possible to determine the localization of the process.

Projection bicuspid valve, or P. optimum bivalve, is located in the horse in the fifth intercostal space on the left, in the middle of the lower third of the chest. During auscultation at this point, both tones are heard, but one of them, systolic, in which the bivalve sounds with particular force, is dominant.

The projection of the tricuspid valve, or P. optimum tricuspid, is on the right side, under the fourth rib, at the level of the middle of the lower third of the chest. Of the two tones that are heard here, the systolic tone of the tricuspid is dominant. It should be noted that on the right side heart tone audible somewhat weaker than on the left side.

Projection of the aortic valve, or P. optimum aortic valve, is located in the fourth intercostal space on the left, slightly below the line drawn through the scapular-shoulder joint. Due to the deep location, this tone is low-intensity and easily mixes with the tone of the pulmonary artery. On the right, in the same intercostal space, this tone is heard, although weaker, but almost pure. Projection of the opening of the pulmonary artery, or. P. optimum of the pulmonary artery, located in the third intercostal space on the left, in the middle of the lower third of the chest. Both tones are heard clearly, but the tone of the pulmonary artery dominates.

In ruminants, the difference lies in the fact that the projection of the bicuspid valve is located in the fourth intercostal space and in the same intercostal space, but slightly higher, there is also the projection of the aortic orifice. The projection of the pulmonary artery is located in the third intercostal space on the left, almost in line with the bicuspid, and the projection of the tricuspid valve protrudes most clearly on the right, in the third intercostal space.

In the pig, the projection of the bicuspid is in the fourth intercostal space on the left, the projection of the aortic orifice is in the third intercostal space, and the pulmonic valve is in the second intercostal space. The projection of the tricuspid valve is on the right, in the third intercostal space.

In the dog, the projection of the bicuspid valve is on the left in the fifth intercostal space above the line dividing the lower third of the chest in half, the projection of the aortic opening in the fourth intercostal space on the left, directly below the line of the humeral tubercle. The projection of the pulmonary artery is in the third intercostal space on the left along the edge of the sternum, and the tricuspid is on the right in the fourth intercostal space at the height of the attachment of the ribs.

Strengthening of heart tones. Changes in the strength of heart tones can be observed simultaneously and separately. Strengthening of both tones is noted in the following cases: a) strengthening of heart contractions with physical stress and fevers; b) when poor diet and in animals with a narrow chest; c) when there is an anemic condition. Heart sounds in this case acquire a clapping character, apparently due to the large difference in the tension of the tissues of the valves and openings during systole and diastole; d) when there is an improvement in the conditions for conducting sound.

Strengthening individual tones is called an accent, or accentuation of heart tones. They speak of an accent of tone in those cases when it stands out sharply from the general sound (accentuates). AT clinical practice the emphasis of the tone of the pulmonary artery, the emphasis on the second aortic tone and the accentuation of the systolic tones matter.

Emphasis on the second aortic tone is noted with an increase blood pressure in arterial system. In healthy horses, an emphasis on the aorta is found at muscle tension and excitation of the animal. In pathological conditions, the emphasis on the aortic valve is observed as a persistent phenomenon. These processes include arteriosclerosis of the initial part of the aorta, an increase in blood pressure in big circle with chronic nephritis, etc. The emphasis on the second tone of the pulmonary artery is observed in cases of increased blood pressure in the pulmonary circulation, when there is difficulty in blood circulation in pulmonary circle with sufficient strength of the right ventricle. Of the diseases in which there is an emphasis on the second tone of the pulmonary artery, it is necessary to name alveolar emphysema, interstitial pneumonia, bicuspid insufficiency and mitral stenosis. It should be noted that in young horses the pulmonary artery tone is much stronger than the aortic tone. With age, the intensity of the aortic tone gradually increases, and the pulmonary artery weakens.

Decreased heart sounds. Heart sounds may appear to be weakened if sound conduction to the periphery worsens. This can be with obesity, subcutaneous emphysema, exudative pericarditis and emphysema, when the heart is removed from the chest. it Need Bear in mind not to recognize the weakening of cardiac activity where it does not exist.

Decreased heart tones associated with impaired contractility heart muscle, observed in myocarditis, myodegeneration of the heart and its expansion. It is also observed when the valves are thickened and deformed, preventing their contraction due to loss of elasticity. A further change leads to the appearance of noise. The weakening of tones may be due to insufficiency of the aortic valve. The weakening is based on the impossibility of the bivalve to move during closure from a stressed state to an even greater voltage during ventricular systole. The highest degree of the disorder is the complete disappearance of heart tones. In cattle, this symptom is characteristic of exudative traumatic pericarditis.

Bifurcation of heart sounds. The bifurcation of cardiac tones is based on either non-simultaneous contraction of both ventricles, which causes a bifurcation of the first tone, or their non-simultaneous relaxation, causing a bifurcation of the second tone. Non-simultaneous work of the ventricles is observed in diseases that unevenly affect both halves of the heart. The conditions for the occurrence of unequal work may be a weakening of the work of the heart and hypertrophy of one ventricle. The weakened ventricle lags behind the healthy one with its contractions, and its first tone is heard separately. The bifurcation can also be on the basis of the defeat of one of the legs of the gisovsky bundle.

In ventricular diastole, the one that works against the lower blood pressure relaxes rather. For bifurcation of the first tone, especially favorable conditions are such when the systole of the left ventricle is shorter than the systole of the right one, and the aorta closes before the pulmonary artery. An increase in blood pressure in the pulmonary circulation causes a bifurcation of the second tone with an emphasis on the pulmonary valve, and an increase in blood pressure in the systemic circulation causes a bifurcation and an emphasis on the aortic valve.

Splitting of heart tones differs from bifurcation only in the degree of severity. When bifurcated, a pause between semitones clearly appears, and when splitting, the impression of tones with pre- or post-beats is obtained. The tone lengthens and splits in the middle.

Galloping rhythm. The gallop rhythm differs from bifurcation in that it acquires a three-term character. It depends on the sharp bifurcation of the tone, when the split-off part is perceived as a separate independent tone. The gallop rhythm is determined with a rapid contraction of the heart; under physical stress, it appears more distinctly. The gallop rhythm can be presystolic, systolic and diastolic in nature.

The presystolic gallop rhythm is noted when the conduction of impulses along the bundle of His between the atria and ventricles is difficult. This leads to a slowdown in the excitation of the ventricles and the appearance of an atrial tone.

Rice. 22. Tonogram. Splitting of the second tone.

The systolic rhythm of the gallop is explained by the non-simultaneous contraction of the right and left ventricles and is based on a violation of conduction along the legs of the bundle of His or their branches.

The diastolic gallop rhythm is characterized by the appearance of an additional tone in the middle of a long pause, i.e., in the middle of diastole. This form in relation to the mechanism of occurrence has not yet been deciphered. There is an assumption that the diastolic gallop rhythm is associated with the existence of a third tone (Obraztsov, Gubergrits). In favor of the existence of the third tone, the graphic recording of the soundtrack speaks, which demonstrates small short-term fluctuations in diastole.

The appearance of the third tone is associated with fluctuations in the tension of the walls of the ventricles due to the blood flowing into it during diastole. With a decrease in the tone and contractility of the ventricular muscle, a change in its tension under the pressure of blood will occur on a large scale, which is why the third tone becomes more sonorous.

The gallop rhythm indicates severe violations in the conduction system of the heart associated with organic diseases of the heart muscle.

Embryocardia. With severe chronic insufficiency heart and with its acute weakening, the pauses become the same duration due to the shortening of a longer pause. Heart tones in this case are compared in strength and character of the sound. Differentiation of the first and second heart sounds becomes difficult. If cardiac activity also becomes more frequent, then by its nature it resembles a fetal heartbeat (embryocardia). Differentiation by cardiac impulse-coincidence of the first tone.