Auscultation of the heart

Auscultation is one of the most important methods of heart examination. It is best to use a stethoscope, which must have a membrane for the best perception of high frequency sounds (phonendoscope). In this case, the membrane is applied to the chest fairly tightly. The informative value of auscultation is highest in the detection of heart defects. In this case, the final diagnosis is often based on listening to the heart. To master this method requires a daily practice, in the process of which you must first learn to correctly perceive a normal auscultatory picture of the heart.

The bell of the phonendoscope is sufficiently tightly applied to the surface of the chest in the area of the projection of the heart. In some patients, excessive hair growth interferes with the hearing, which sometimes must be shaved off or moistened with soapy water in connection with this. Auscultation should be carried out first of all in the position of the patient lying on his back, in some cases (see below), supplemented by listening in the position on the left side, on the abdomen, standing or sitting, while holding the breath on inhalation or exhalation, after physical exertion.

All these techniques allow us to discover a number of symptoms that are of great diagnostic importance and often determine the tactics of patient management.

Heart Tones

In healthy people, over the entire heart area, two tones are heard:

1. I tone, which occurs at the beginning of the systole of the ventricles and is called systolic, and
2. II tone, arising at the beginning of diastole and called diastolic.

The origin of heart tones is primarily associated with the fluctuations that arise in its valves in the process of contractions of the myocardium.

I tone occurs at the beginning of the systole of the ventricles already at the time when the valves of the atrioventricular left (mitral) and right (tricuspid) valves slammed, i.e., during the isometric contraction of the ventricles. The greatest importance in its occurrence is attached to the tension of the left and right atrioventricular valves, consisting of an elastic tissue. In addition, in the formation of the first tone, the vibrational movements of the myocardium of both ventricles play a role in the process of their systolic stress. Other components of I tone are less important: vascular is associated with fluctuations in the initial segments of the aorta and pulmonary trunk when they are stretched with blood, atrial is associated with their contraction.

II tone occurs at the beginning of the diastole as a result of slamming the valves of the aorta and pulmonary artery valves.

Under normal conditions it is relatively easy to distinguish I tone from II tone, since a comparatively short systolic pause is determined between them. Between the I and II tone in the diastole period, the pause will be much longer. With increasing rhythm, there may be difficulties in identifying tones. It should be borne in mind that I tone corresponds to a heart beat or an easily detectable pulsation of the carotid artery.

Heart auscultation points

The emergence of tones, as well as other sounds in the heart, as mentioned above, is primarily due to fluctuations in the valvular valves that are located between the atria and ventricles and between the ventricles and large vessels. Each valve hole corresponds to a specific point for listening. These points do not exactly coincide with the projection of the valves on the front chest wall. Sounds that occur in the valve openings are conducted according to the current of the blood.

The following points for the best listening of heart valves are established:

1. mitral valve - the tip of the heart;
2. tricuspid valve - the lower part of the sternum;
3. the aortic valve - the second intercostal space on the right near the edge of the sternum;
4. the valve of the pulmonary artery - the second intercostal space on the left near the edge of the sternum;
5. the so-called V point - the third intercostal space on the left side of the sternum; Auscultation of this area allows you to hear more clearly the diastolic noise that occurs when the aortic valve is deficient.

II tone and its components associated with slamming the semilunar valves of the aorta and pulmonary artery valves are always better audible and evaluated in the auscultative pattern in the second intercostal space on the left or right side of the sternum margin. I tone associated primarily with the strain of the mitral valve flaps is evaluated with auscultation at the apex of the heart, as well as at the lower edge of the sternum. Thus, we speak of strengthening or weakening of the second tone when listening on the basis of the heart (the second intercostal space), but about strengthening or weakening of the I tone - when listening at the top. If the second tone consists of two components when listening on the basis of the heart, we can talk about its bifurcation. If we listen to the additional component following the second tone at the top, we should not speak of the splitting or bifurcation of the second tone, but of the appearance of an additional tone following the second tone and, obviously, associated with the oscillations of the valve.

The volume of heart sounds can change primarily under the influence of non-cardiac factors. They can be worse to listen to when the thickness of the chest is increased, in particular due to a larger muscle mass, when the fluid accumulates in the pericardial cavity. Conversely, with a thinner chest in lean faces and especially with a more frequent rhythm (faster movement of the valves), heart sounds may be more loud.

Children and asthenics sometimes manage to hear III and IV tones.

The third tone is heard soon (after 0.15 s) after the second tone. It is caused by fluctuations in the muscle of the ventricles with rapid passive filling them with blood (from the atria) at the beginning of the diastole.

IV tone occurs before the I tone at the end of the diastole of the ventricles and is associated with their rapid filling due to contractions of the atria.

Pathological changes in heart tones

Attenuation of both tones can be observed with a marked diffuse lesion of the ventricular myocardium and a decrease in their contractility.

Attenuation of I tone at the apex of the heart is also observed in the defeat of heart valves, primarily mitral, as well as trivalent, which leads to the absence of the so-called period of closed valves and a decrease in the valve component of I tone. I tone weakens also at the expressed heart failure at the expense of decrease in the muscular component.

Strengthening I tone can be observed with a decrease in filling of the ventricles to the beginning of the systole due to its muscular component, in which I tone is often defined as "clapping".

Significant fluctuations in I tone intensity are observed with atrial fibrillation due to differences in diastolic pauses, hence, in filling the left ventricle.

Attenuation of II tone occurs with low pressure in large vessels, a decrease in their blood filling. Attenuation of the second tone can occur with damage to the valves of the aorta and pulmonary artery, which leads to a violation of their collapse.

II tone increases with increasing pressure in large vessels - the aorta or pulmonary artery; while talking about the accent of the II tone, respectively, on this or that vessel. In this case, the II tone, for example, to the right of the sternum, is heard as substantially more intense than on the left, and vice versa. The accent of the second tone is explained by the quicker closing of the corresponding valves and a louder sound that is perceived during auscultation. The accent of tone II on the aorta is determined with arterial hypertension, as well as with pronounced sclerotic changes of the aorta with a decrease in the elasticity of its walls. The accent of the second tone on the pulmonary artery is determined by increasing the pressure in it in patients with mitral defects and pulmonary heart.

The bifurcation of tones is said in the case when their main components are captured separately. Usually, the bifurcation of the second tone is established. It can be associated with a non-simultaneous collapse of the valves of the aorta and pulmonary artery, which is associated with different duration of contraction of the left and right ventricles due to changes in the large and small circulatory circulation, respectively. With increasing pressure, for example in the pulmonary artery, the second component of tone II is associated with a later collapse of the pulmonary artery valve. In addition, bifurcation of the second tone is associated with increased blood filling in the small or large circle of blood circulation.

A small bifurcation of the second tone, as always, heard on the basis of the heart, i.e. In the second intercostal space, can also arise under physiological conditions. With a deep inspiration due to an increase in blood flow to the right heart, the duration of the right ventricular systole may be somewhat larger than the left one, and therefore splitting of the second tone is heard on the pulmonary artery, the second component being associated with the collapse of the pulmonary artery valve. This physiological splitting of the second tone is better audible in young people.

Later, the collapse of the pulmonary valve in comparison with the aortic valve is detected with the expansion of the right ventricle, for example, with stenosis of the pulmonary artery or when excitation is disturbed by the right leg of the atrioventricular bundle (the bundle of the Hyis), which also leads to late collapse of the valves of this valve.

With an atrial septal defect, an increase in the volume of the blood in the right atrium and then in the right ventricle results in a wide splitting of the second tone, but since the right and left atrium are in constant communication with such a defect, the volume of the blood of the left and right ventricles fluctuates, therefore one direction and coincides with the respiratory cycle. This leads to a fixed splitting of the II tone on the pulmonary artery, which is pathognomonic for the atrial septal defect.

With pulmonary hypertension in patients with chronic lung diseases, splitting of the second tone is less pronounced and distinct, since the right ventricle (although it works against increased pressure in the lungs) is usually hypertrophied, and therefore its systole does not lengthen.

Additional heart sounds arise for many reasons. The opening of the mitral valve usually occurs silently at the beginning of the diastole. When sclerosing the valves of the mitral valve in patients with mitral stenosis, their opening at the beginning of the diastole is limited, so the flow of blood causes the oscillations of these valves, perceived as an additional tone. This tone is heard soon after the II tone, but only at the apex of the heart, which indicates its connection with the vibrations of the mitral valve. A similar tone of opening of the tricuspid valve is heard at the bottom of the sternum, however, it is rare.

Systolic tones of exile are heard soon after I heart tone, they arise due to fluctuations in the aortic or pulmonary artery valve, so it is better heard in the second intercostal space on the left or right side of the sternum margin. Their appearance is also associated with the appearance of vibrations of the walls of large vessels, especially when they expand. The aortic tone of exile is best heard at the aortic point. It is most often combined with congenital aortic stenosis. Dividing the I tone can be observed in violation of intraventricular conduction in the legs of the atrioventricular bundle, which leads to a delay in the systole of one of the ventricles.

Transplantation of the aortic or mitral valves is now performed quite often. Use an artificial ball valve or biological prosthesis. Mechanical valves cause the formation of two tones in each heart cycle, the tone of opening and the tone of closure. With a mitral prosthesis, a loud tone of closure is heard after the I heart tone. The opening tone follows the second tone, as in mitral stenosis.

The rhythm of the canter is a three-beat rhythm of the heart, which is heard against the background of tachycardia, i.e., rapid rhythm, and indicates a severe lesion of the myocardium of the ventricles. The additional tone at the rhythm of the canter can be heard at the end of the diastole (before I tone) - the presystolic rhythm of the gallop and at the beginning of the diastole (after the II tone) - the proto-diastolic rhythm of the gallop. The rhythm of the canter is determined either at the apex of the heart, or the third - fourth intercostal space to the left of the sternum.

The origin of these additional tones is associated with rapid filling of the ventricles at the beginning of the diastole (additional III tone) and during the period of the systole of the atria (an additional IV tone) under conditions of sharply altered properties of the myocardium with a violation of its extensibility. When they occur against the background of tachycardia, sounds are heard, the rhythm of which resembles a running gallop galloping. Moreover, often these III and IV heart tones are audible almost simultaneously, causing the formation of a three-term rhythm. In contrast to normal III and IV heart tones, which occur in young people with the usual heart rhythm, the gallop rhythm occurs with severe myocardial damage with left ventricular dilatation and heart failure.

An additional tone preceding the first tone against the relatively rare heart rhythm can be heard sometimes in elderly people with little changed heart. III and IV tones, including those corresponding to the rhythm of the canter, are better audible in the position of the patient on the left side.