Материал: General propedeutics of internal diseases_Nemtsov-LM_2016

For detection of the left border of absolute cardiac dullness, the pleximeter-finger is placed slightly outside the border of relative cardiac dullness, and then moved medially to dullness. The left border of absolute cardiac dullness is normally 1.5-2 cm medially of the left midclavicular line.

For detection of the superior border of absolute cardiac dullness, the pleximeter-finger is placed on the superior border of relative cardiac dullness and then moved downward to dullness. The superior border of absolute cardiac dullness is normally at the level of the 4th rib.

For more accurate determination of superior border the immediate percussion (Obraztcov method) is performed on two overlying ribs above a dulled sound (first – the 3-d control rib, then - the 4-th test rib). If the percussion by ribs yields an identical note, the border is placed on the inferior edge of a lower (the 4-th) rib. If more dulled percussion sound is found above a lower rib, the superior border is defined on the upper edge of the 4-th rib. In norm the superior border of absolute dullness of heart settles down at a level of the inferior edge of the 4-th rib.

The area of cardiac dullness can be modified by extracardiac factors. At high position of the diaphragm, the heart assumes a horizontal position and its transverse dimensions thus increase. When the diaphragm is low, the heart assumes the vertical position and its transverse diameter is thus diminished. Accumulation of liquid or air in one pleural cavity displaces cardiac dullness toward the healthy side; in atelectasis and pneumosclerosis, or in the presence of pleuropericardial adhesion the borders of cardiac dullness are displaced to the affected side. The area of absolute cardiac dullness markedly diminishes or disappears in pulmonary emphysema, while it increases in pneumosclerosis. The area of absolute dullness is also enlarged in the anterior displacement of the heart (e.g. by a mediastinal tumour, due to accumulation of fluid in the pericardium, or in dilatation of the right ventricle). The borders of relative dullness are displaced in the presence of enlarged heart chambers. Displacement to the

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right is due to dilatation of the right atrium and the right ventricle. If the left atrium or the conus of the pulmonary trunk is enlarged, the area of relative dullness is displaced upwards. Dilatation of the left ventricle displaces the area of relative dullness to the left. It should be remembered that a markedly enlarged and hypertrophied right ventricle displaces the left ventricle and can also displace the border of relative dullness to the left. Aortic dilatation increases the dullness area in the second interspace.

Auscultation of heart: heart sounds

Anatomical and physiological bases of auscultation of the heart

The sounds produced by a working heart are called heart sounds. Two sounds can be well heard in a healthy subject; the first sound, which is produced during systole and the second sound, which occurs during diastole.

A mechanism by which the heart sounds are produced connects with the phases of the cardiac cycle. The heart contraction begins with the systole of the atria, which is followed by contraction of the ventricles. During the early systole the following phases are distinguished: (1) asynchronous contraction; the myocardium is involved only partly and the intraventricular pressure does not increase; (2) isometric contraction; it begins when the main mass of the myocardium is involved; atrioventricular valves are closed during this phase and the intraventricular pressure markedly increases; (3) ejection phase; the intraventricular pressure increases to level with that in the main vessels; the semilunar valves open. As soon as the blood has been ejected, the ventricles relax (diastole) and the semilunar valves close. The ventricles continue relaxing after the closure of the atrioventricular and semilunar valves until the pressure in them is lower than in the atria (isometric relaxation phase). The atrioventricular valves then open to admit blood into the ventricles. Since the difference between pressures in the atria and the ventricles is great during the early diastole, the ventricles are quickly filled

(ventricle rapid filling phase). The blood flow then slows down (flow filling phase). Atrial systole begins, and the cardiac cycle is repeated.

The first sound is produced by several factors. One of them is the valve component, i.e. vibrations of the cusps of the atrioventricular valves during the isometric contraction phase, when the valves are closed. The second component is muscular, and is due to the myocardial isometric contraction. The intensity of myocardial and valves vibrations depends on the rate of ventricular contractions: the higher the rate of their contractions and the faster the intraventricular pressure grows, the greater is the intensity of these vibrations. The first heart sound will thus be more resonant. The third component of the first heart sound is the vascular one. This is due to vibrations of the nearest portions of the aorta and the pulmonary trunk caused

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by their distention with the blood during the ejection phase.

The second sound is generated by vibrations arising at the early diastole when the semilunar cusps of the aortic valve and the pulmonary trunk are shut (the valve component) and by vibration of the walls at the point of origination of these vessels (the vascular component).

Both sounds can be heard over the entire precordium but their strength changes depending on the proximity of the valves involved in the formation of the first or second sound. Therefore, in order to assess correctly the findings of auscultation, it is necessary to know the sites where the valves project on the chest wall (auscultatory valve areas) and also areas where the sounds produced by a valve can be better heard.

Projections of the valves on the anterior chest wall are very close to one another:

-mitral valves projects to the left of the sternum at the 3-rd costosternal joint;

-tricuspid valve - on the sternum midway between the 3-rd left and 5- th right costosternal joints;

-valves of the pulmonary trunk are projected in the 2-nd intercostal space, to the left of the sternum;

-aortic valves are projected in the middle of the sternum at the level of the 3-rd costosternal joint.

Since all heart valves are projected on a small area of the chest, it is difficult to decide which of them is damaged if the valves are auscultated at sites of their actual projections. Perception of sounds generated in the heart depends on the distance from the valve to its projection on the chest wall and on sound conduction by the course of the blood flow. It is therefore possible to find certain sites on the chest where sounds of each valve can be better heard.

The auscultatory areas (points) are as follows:

(1)area of the apex beat - for the mitral valves because the vibrations are well transmitted by the firm muscle of the left ventricle and the cardiac apex is at the nearest distance to the anterior chest wall during systole;

(2)lower part of the sternum near its junction with the xiphoid process (the right-ventricular area) - for the tricuspid valves;

(3)valves of the pulmonary trunk are best heard at its anatomical projection onto the chest, i.e. in the second intercostal space, to the left of the sternum;

(4)aortic valves are best heard in the second intercostal space, to the right of the sternum where the aorta is the nearest to the anterior chest wall;

(5)heart sounds which are associated with the contractions of aortic and mitral valves or which develop during its affections can be heard to the left of the sternum at the 3-rd and 4-th costosternal joints (the so-called fifth listening post at the Botkin-Erb point).

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Rules of auscultation of heart

-The heart is usually auscultated by a stethoscope or a phonendoscope, but direct (immediate) auscultation is also used.

-The condition of the patient permitting the heart sounds should be heard in various postures of the patient: erect, recumbent, after exercise (e.g. after repeated squatting).

-Sounds associated with the mitral valve pathology are well heard when the patient lies on his left side, since the heart apex is at its nearest position to the chest wall; aortic valve defects are best heard when the patient is in the upright posture or when he lies on his right side.

-The heart sounds are better heard if the patient is asked to inhale deeply and then exhale deeply and keep breath for short periods of time so that the respiratory sounds should not interfere with auscultation of the heart.

-The valve sounds should be heard in decreasing order of their affection frequency. The mitral valve should be heard first (at the heart apex); next follows the aortic valve (in the second intercostal space to the right of the sternum), the pulmonary valve (in the second intercostal space, to the left of the sternum), tricuspid valve (at the base of the xiphoid process), and finally the aortic and mitral valve again at the Botkin-Erb point. If any deviations from normal sounds have been revealed at these points, the entire heart area should be auscultated thoroughly.

Heart sounds

Normal heart sounds

The first sound is produced during systole, after a long pause. It is best heard at the heart apex since the systolic tension of the left ventricle is more pronounced than that of the right ventricle. The first sound is longer and louder than the second heart sound. The second sound is generated during diastole, after a short pause, and is best heard at the heart base because it is produced by the closure of the semilunar cusps of the aortic and pulmonary trunk valves. As distinct from the first sound, the second sound is shorter and higher. The tone of the heart sounds may change in pathology, and in order to differentiate between the first and second sounds it should be remembered that the first sound coincides in time with the apex beat (if the latter can be palpated) or with the pulse of the aorta and the carotid artery. Sometimes the third and the fourth sounds can be heard, especially in children and in thin youths.

The third sound is caused by vibrations generated during quick passive filling of the ventricles with the blood from the atria during diastole of the heart; it arises in 0.15-1.12 s from the beginning of the second sound.

The fourth sound is heard at the end of ventricular diastole and is produced by atrial contractions during quick filling of the ventricles with

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blood.

The third and fourth sounds are low-pitch and soft and are therefore hardly heard in normal subjects. But they are clearly seen on a phonocardiogram. These sounds are better heard in immediate (direct) auscultation. The presence of the third and fourth sounds in the middle-aged usually indicates severe affection of the heart muscle.

Changes in the heart sounds

The heart sounds may increase or decrease their intensity, the tone, or length; they may be split or reduplicated, or adventitious sound may appear.

Intensity of the heart sounds may depend on conditions of the sound wave transmission, i.e. on the extracardiac causes. If subcutaneous fat or muscles of the chest are overdeveloped, or there are lung emphysema, liquid in the left pleural cavity, and some other affections that separate the heart from the anterior chest wall, the intensity of the heart sounds decreases. If conditions for sound transmission are improved (thin chest wall, the lung edges are sclerosed, the heart is pressed against the anterior chest wall by a growing tumour in the posterior mediastinum, etc.), the intensity of the heart sounds increases. The sounds can also be increased by the resonance in large empty cavities filled with air (a large cavern in the lung, large gastric airbubble). The intensity of the heart sounds also depends on the composition of the blood flowing through the heart: if the blood viscosity decreases (in anemia) the intensity increases.

Intensity of the heart sounds can decrease in decreased myocardial contractility in patients with myocarditis, myocardial dystrophy, cardiosclerosis, collapse, and accumulation of fluid in the pericardial cavity.

Both heart sounds can be increased due to the effect of the sympathetic nervous system on the heart. It occurs in physical and emotional strain, during exercise, and in patients with exophthalmic goitre.

Changes of only one of heart sounds are very important diagnostically.

Intensity of the first heart sound diminishes in the mitral and aortic valve insufficiency. The cusps of the affected mitral valve fail to close completely the left atrioventricular orifice during systole. Part of the blood is thus regurgitated to the left atrium. The pressure of the blood is below norm against the ventricular walls and the cusps of the mitral valve, and the valvular and muscular components of the first heart sound markedly diminish. The period of closed valves is absent also during systole in the aortic valve insufficiency. It means that the valves and muscle components of the first heart sound will also diminish significantly.

In tricuspid and pulmonary valve failure, the diminution of the first heart sound will be better heard at the base of the xiphoid process due to the diminution of the muscular and valves components of the right ventricle.

The first sound can be diminished at the heart apex in stenotic aortal

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