Heart sounds: the first (systolic), the second (diastolic) - norm and pathology

The first phonendoscopes were stacked sheets of paper or hollow bamboo sticks, and many doctors used only their own organ of hearing. But they all wanted to hear what is happening inside the human body, especially when it comes to such an important organ as the heart.

Heart sounds are sounds that are formed in the process of shrinking the walls of the myocardium. Normally, a healthy person has two tones, which can be accompanied by additional sounds depending on which pathological process develops. A doctor of any specialty must be able to listen to these sounds and interpret them.

Heart cycle

The heart beats at a frequency of sixty to eighty beats per minute. This, of course, is the average value, but ninety percent of the people on the planet fall under it, which means you can take it for granted. Each stroke consists of two successive components: systoles and diastoles. The systolic tone of the heart, in turn, is divided into atrial and ventricular. By the time it takes 0.8 seconds, but the heart manages to contract and relax.

Systole

As already mentioned above, there are two components involved. Initially, the systole of the atria is moving: their walls contract, blood under pressure enters the ventricles, and the valve flaps collapse. It is the sound of the closing valves that can be heard in the phonendoscope. This whole process lasts 0.1 seconds.

Then comes the systole of the ventricles, which is a much more complicated job than it does with the atria. To begin with, we note that the process lasts three times longer - 0.33 seconds.

The first period is ventricular tension. It includes the phases of asynchronous and isometric contractions. It all begins with the fact that the eclectic impulse spreads through the myocardium, It stimulates individual muscle fibers and causes them to spontaneously contract. Because of this, the heart shape changes. Due to this, the atrioventricular valves close tightly, increasing pressure. Then a powerful contraction of the ventricles occurs, and the blood enters the aorta or pulmonary artery. These two phases take 0.08 seconds, and in the remaining 0.25 seconds the blood enters the main vessels.

Diastole

Here, too, everything is not so simple as it might seem at first glance. Ventricular relaxation lasts 0.37 seconds and occurs in three stages:

1. Proto-diastolic: after the blood has left the heart, the pressure in its cavities decreases, and the valves leading to the large vessels are closed.
2. Isometric relaxation: the muscles continue to relax, the pressure drops even more and aligns with the atrial. From this, the atrioventricular valves open, and the blood from the atria enters the ventricles.
3. Filling of the ventricles: on the pressure gradient, the fluid fills the lower chambers of the heart. When the pressure levels, the blood flow gradually slows down, and then stops.

Then the cycle is repeated again, starting with systole. Its duration is always the same, but the diastole may contract or elongate depending on the speed of the heartbeat.

The mechanism of formation of I tone

Strange as it may sound, but 1 tone of the heart consists of four components:

1. Valve - he leads in the formation of sound. In fact, these are the oscillations of the valves of the atrioventricular valves at the end of the systole of the ventricles.
2. Muscular - oscillatory movements of the walls of the ventricles with contraction.
3. Vascular - stretching the walls of the main vessels at a time when blood is being injected into them under pressure.
4. Atrial - systole of the atria. This is the immediate beginning of the first tone.

The mechanism of formation of II tone and additional tones

So, 2 tone of the heart includes only two components: valvular and vascular. The first is a sound that arises from blood strikes on the valves of the artifact and the pulmonary trunk at the moment when they are still closed. The second, that is, the vascular component, is the movements of the walls of large vessels, when the valves finally open.

In addition to the two main, there are 3 and 4 more tones.

The third tone is the variability of the ventricular myocardium during diastole, when the blood flows passively into the area of lower pressure.

The fourth tone appears at the end of the systole and is associated with the end of the expulsion of blood from the atria.

I tone characteristic

Heart sounds depend on many causes, both intra- and extracardiac. Soundness of 1 tone depends on the objective state of the myocardium. So, first of all loudness is ensured by tight closing of the heart valves and the speed with which the ventricles contract. Of secondary importance are such features as the density of the valves of the atrioventricular valves, as well as their position in the heart cavity.

It is best to listen to the first tone of the heart on its top - in 4-5 intercostal space to the left of the sternum. For more precise coordinates, it is necessary to perform percussion of the chest in this area and clearly define the boundaries of cardiac dullness.

Characteristics of the 2nd tone

To hear it, it is necessary to put the bell of the phonendoscope over the base of the heart. This point is slightly to the right of the xiphoid process of the sternum.

The volume and clarity of the second tone also depends on how closely the valves close, only now they are semilunar. In addition, the speed of their operation, that is, closing and oscillating free ends, affects the reproduced sound. And additional qualities are the density of all structures involved in the formation of tone, as well as the position of the valves during the expulsion of blood from the heart.

Rules for listening to heart tones

The sound of the heart is probably the most calming in the world, after white noise. Scientists have a hypothesis that it is he who hears a child in the prenatal period. But in order to detect damage to the heart, it's not enough to just listen to how it beats.

First of all, you should practice auscultation in a quiet and warm room. The position of the person being examined depends on which valve should be carefully examined. This may be the position lying on the left side, vertically, but with the body tilted forward, on the right side, and so on.

The patient should seldom and shallowly breathe, and at the request of the doctor to hold his breath. In order to clearly understand where the systole is, and where the diastole, the doctor should in parallel listen to the carotid artery, the pulse on which completely coincides with the systolic phase.

Cardiac auscultation

After the preliminary determination of absolute and relative cardiac dullness, the doctor listens to the heart's tones. Begins, as a rule, from the top of the organ. There, the mitral valve is well audible. Then go to the valves of the main arteries. First to the aortic - in the second intercostal space to the right of the sternum, then to the pulmonary artery - at the same level, only to the left.

The fourth point for listening is the base of the heart. It is located at the base of the xiphoid process, but it can move sideways. So the doctor should check what kind of heart, and the electric axis, to accurately hear the three-leaf valve.

They complete the auscultation at the Botkin-Erba point. Here you can hear the aortic valve. It is located in the fourth intercostal space to the left of the sternum.

Additional tones

The sound of the heart does not always resemble rhythmic clicks. Sometimes, more often than he would like, he takes on bizarre forms. Some of them doctors have learned to detect only by listening. These include:

- Click the mitral valve. It can be heard near the apex of the heart, it is associated with the organic changes in valve flaps and appears only with the acquired heart disease.

- Systolic click. Another type of mitral valve defect. In this case, its wings loosely close and seem to turn outward during systole.

- Perecardton. Detects with adhesive pericardial. It is associated with excessive distension of the ventricles due to the formation of the inside of the muzzle.

- The rhythm of the quail. Occurs with mitral stenosis, manifested by the intensification of the first tone, the accent of the second tone on the pulmonary artery and the click of the mitral valve.

- The rhythm of the canter. The cause of his appearance is a decrease in myocardial tone, appears on the background of tachycardia.

Extracardiac causes of intensification and attenuation of tones

The heart beats in the body all life, without breaks and rest. So, when it wears out, then in the measured sounds of his work appear outsiders. The causes of this can be either directly related to heart damage, and do not depend on it.

Strengthening the tones contribute to:

- cachexia, anorexia, thin chest wall;

- atelectasis of the lung or part of it;

- tumor in the posterior mediastinum, moving the lung;

- infiltration of the lower lobes of the lungs;

Bullae in the lungs.

Attenuation of cardiac tones:

Excessive weight;

- development of the muscles of the chest wall;

- subcutaneous emphysema;

- the presence of fluid in the chest cavity;

- exudate pericarditis.

Intracardial causes of heart tone intensification and weakening

Heart tones are clear and rhythmical when a person is at rest or in a dream. If he came into motion, for example, climbed the stairs to the doctor's office, then this can cause a strengthening of the heart sound. Also, the acceleration of the pulse may be caused by anemia, diseases of the endocrine system, etc.

Deaf heart tone is heard with acquired heart defects, such as mitral or aortic stenosis, valve failure. Its contribution is the stenosis of the aorta in the departments close to the heart: the ascending part, the arc, the descending part. Muted heart tones are associated with an increase in the mass of the myocardium, as well as with inflammatory diseases of the heart muscle, leading to dystrophy or sclerosis.

Heart murmurs

In addition to tones, the doctor can hear other sounds, so-called noise. They are formed from the swirls of blood flow that passes through the heart cavity. Normally, they should not be. All the noise can be divided into organic and functional.

1. Organic appear when the body has anatomical, irreversible changes in the valve system.
2. Functional noise is associated with impaired innervation or feeding of papillary muscles, an increase in heart rate and blood flow velocity, a decrease in its viscosity.

Noises can accompany heart tones, but can be independent of them. Sometimes the noise of friction of the pleura in inflammatory diseases is superimposed on the heartbeat, and then it is necessary to ask the patient to hold his breath or lean forward and once again to perform an auscultation. This simple trick helps you avoid mistakes. As a rule, when listening to pathological noise, they try to determine which phase of the cardiac cycle they are in, find the place for the best listening, and collect the noise characteristic: strength, duration and direction.

Noise properties

By the timbre there are several types of noise:

- mild or blowing (usually not associated with pathology, often in children);

- rough, scraping or sawing;

- musical.

Duration distinguish:

- short;

- long;

By volume:

- Quiet;

- loud;

- decreasing;

- increasing (especially with narrowing of the left atrioventricular orifice);

- increasing-decreasing.

The change in loudness is recorded during one of the phases of cardiac activity.

Height:

- high-frequency (with aortic stenosis);

- low-frequency (with mitral stenosis).

There are some general patterns in the auscultation of noise. First, they are well listened to in the locations of the valves, because of the pathology of which they were formed. Secondly, the noise radiates in the direction of the blood flow, and not against it. And thirdly, like heart sounds, pathological noises are best heard where the heart is not covered by the lungs and is tightly attached to the chest.

Systolic noise is better to listen in lying position, because the blood flow from the ventricles becomes easier and faster, and diastolic - sitting, because under the force of gravity, the fluid from the atria quickly enters the ventricles.

Differentiate noise by their location and phase of the heart cycle. If noise in the same place appears in both systole and diastole, then this indicates a combined lesion of one valve. If in the systole the noise appears at one point, and in the diastole - in another - then this is a combined defeat of the two valves.