Материал: General propedeutics of internal diseases_Nemtsov-LM_2016

closure of the cusps of the affected valve (regurgitation murmur).

Properties of murmurs

The following characteristics of murmurs should be determined during auscultation:

(1)the relation of the murmur to the phase of the heart activity (to systole or diastole);

(2)the features, character, strength, and length of murmur;

(3)localization of the murmur, i.e. the area where this murmur is heard

best;

(4)direction of transmission (radiation).

The relation of murmurs to systole or diastole is determined by the same signs that are used to differentiate between the first and the second heart sounds. Systolic murmur appears with the first heart sound, during a short pause of the heart; it is synchronous with the apex beat and the carotid pulse. Diastolic murmur follows the second sound, during the long pause of the heart. Three types of diastolic murmurs are distinguished: (1) protodiastolic murmur which arises at the very beginning of diastole, immediately after the second heart sound; (2) mesodiastolic murmur which is

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heard soon after the second heart sound; (3) presystolic murmur which appears at the end of diastole. Murmurs may be pansystolic and pandiastolic murmurs which arise at the very beginning of systole (or diastole) and longs to the end of systole (or diastole).

Character of murmur. By their character, murmurs may be soft, blowing, or on the contrary rough, grating or grazing sounds; musical murmurs can also be heard. By duration, heart murmurs are classified as short and long, and by their intensity as soft and loud.

The intensity of the noise may change with the phase of the heart activity. Murmurs may become weaker (decrescendo) or louder (crescendo), and crescendo-decrescendo (diamond-shaped). Decrescendo murmurs occur more frequently. This can be explained as follows: as blood begins flowing from one heart chamber to another or from the heart to the main vessel, the difference in pressures in two chambers is high and the blood flow rate is therefore high as well. But as the blood is expelled, the pressure inside the chamber from which the blood is ejected gradually decreases, the blood flow rate slows down, and the noise intensity decreases. Presystolic murmur has an increasing character and occurs mostly in stenosis of the anterior left atrioventricular orifice, at the very end of ventricular diastole, when atrial systole begins to increase the blood outflow from the left atrium to the left ventricle. Systolic crescendo-decrescendo (diamond-shaped) murmur presents in aortic stenosis.

Location of the murmur corresponds to the best listening post of that particular valve where this murmur is generated. In certain cases, however, murmurs are better heard at a distance from the point where they are generated, provided their transmission is good. Murmurs are well transmitted in the direction of the blood flow. They are better heard in areas where the heart is close to the chest wall and where it is not covered by the lungs.

Systolic murmur due to mitral valve incompetence is best heard at the heart apex. It can be transmitted by the firm muscle of the left ventricle to the axillary area or by the course of the backward blood flow from the left ventricle to the left atrium, i.e. into the second and third interspace, to the left of the sternum.

Diastolic murmur generated in a narrowed left atrioventricular orifice is usually heard over a limited area at the heart apex.

Systolic murmur due to stenosed aortic orifice is heard in the second interspace, to the right of the sternum. As a rule, it is well transmitted by the course of the blood flow onto the carotid arteries. Since this heart defect is characterized by a rough and loud sound, it can be determined in auscultation over the entire heart region and be transmitted to the interscapular space.

Diastolic murmur due to aortic valve incompetence is better heard not over the aortic valve but rather at the Botkin-Erb point, where it is transmitted by the back flow of blood from the aorta to the left ventricle.

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Systolic murmur associated with tricuspid insufficiency is best heard at the base of the xiphoid process, since the right ventricle is the closest to the chest wall at this point, from which the sound can be transmitted upwards and to the right, in the direction of the right atrium. In the rare heart disease associated with stenosis of the right atrioventricular orifice, the diastolic murmur is heard over a limited area at the base of the xiphoid process.

It should be remembered that murmurs are best heard in certain postures of the patient. Systolic murmurs associated with incompetence of atrioventricular valves or with stenosis of the aortic or pulmonic orifice, are best heard with the patient in the recumbent posture because the blood flow from the ventricles is facilitated and the blood-flow rate increases. Diastolic murmurs arising due to stenosis of the atrioventricular orifice or incompetence of the aortic valve and the valve of pulmonary trunk are better heard in the upright position, since the blood flow to the ventricles from the atria or from the vessels (in insufficiency of the corresponding valves) is thus facilitated and the blood-flow rate increases.

Differentiation of murmurs

If several murmurs are heard simultaneously over different valves, it is necessary to determine the affected valves and the character of their affections. Systolic and diastolic murmurs over one valve indicate its composite affection, i.e. incompetence of the valve and stenosis of the orifice. If systolic murmur is heard over one valve and diastolic murmur over the other, a combined affection of two valves can be diagnosed.

It is more difficult to decide whether one or two valves are affected if murmurs can be heard at various listening points during one and the same phase of heart activity. The character of the murmur should then be analyzed. If a soft and blowing murmur is heard over one valve and rough and grating over the other, the murmurs are generated by two different affected valves. By moving the stethoscope bell along the line connecting the two valves, the changes in the murmur intensity should be followed. If at some point of the line the murmur disappears or weakens markedly, and then again becomes louder, it will in most cases indicate affection of two valves. If the murmur decreases or increases as the stethoscope bell moves in the direction of the second valve, it usually indicates affection of only one valve. But this is not an indisputable sign because the degree of valve affection may differ too, and an independent, though less loud, murmur will then be heard over milder stenotic affection. The character of murmur transmission helps differentiation. For example, systolic murmur occurring in mitral valve incompetence is transmitted into the axillary region. It may be heard also over the aortic valve but it will not be transmitted onto the carotid arteries (as distinct from systolic murmur associated with stenosis of the aortic orifice).

During auscultation of the heart, it is necessary to differentiate between functional and organic, and between endocardial and exocardial murmurs.

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The following properties of functional murmurs help differentiate them from organic murmurs:

(1)in most cases of functional murmurs are systolic;

(2)functional murmurs are not permanent and may arise and disappear when the person changes his posture, after exercise and during various respiratory phases;

(3)they are mostly heard over the pulmonary trunk and less frequently over the heart apex;

(4)functional murmurs are transient and are rarely heard during the entire systole; these are soft and blowing sounds;

(5)the murmurs are normally heard over a limited area and are not transmitted to long distances from their source;

(6)functional murmurs are not accompanied by other signs of valve affections (e.g. enlargement of the heart chambers or changes in the heart sounds).

Systolic apex murmur

Systolic murmur can be heard at the point of apex beat, which is the main sign of mitral incompetence. It arises during systole when the stream of blood passes a narrow slit leading from the left ventricle to the left atrium. The systolic murmur is synchronous with the first sound. It can be transmitted by the firm muscle of the left ventricle to the axillary area or by the course of the backward blood flow from the left ventricle to the left atrium, i.e. into the second and third interspace, to the left of the sternum. Auscultation findings are confirmed and verified by phonocardiography. The amplitude of the first sound is decreased on a PCG taken at the heart apex; systolic murmur occupies the entire pause between the first and second heart sounds.

Diastolic apex murmur

Diastolic murmur is characteristic of mitral stenosis because the passage from the left atrium to the ventricle during diastole is narrowed. This murmur can be heard to follow the mitral valve opening sound (protodiastolic murmur) because the velocity of the blood flow in early diastole is higher due to the pressure difference in the atrium and the ventricle. The murmur disappears when the pressures equalize. If stenosis is not pronounced, the murmur can be heard only at the end of diastole, immediately before systole proper (presystolic murmur); it arises during acceleration of the blood flow at the end of ventricular diastole because of the early atria systole. Diastolic murmur can be heard in mitral stenosis during the entire diastole. It increases before systole and joins the first snapping sound.

Murmurs of functional etiology can also be heard in aortic incompetence at the heart apex. If the left ventricle is markedly dilated, relative mitral incompetence develops and systolic murmur can be heard at the heart apex. Diastolic murmur (presystolic, or Austin Flint, murmur) can

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sometimes be heard. It arises due to an intense regurgitation of the blood that moves aside the mitral valve cusp to account for functional mitral stenosis.

Systolic murmur at the second intercostal space by the right edge of a sternum

Rough systolic murmur over the aorta is characteristic of aorta stenosis. This murmur is generated by the blood flow through the narrowed orifice. It is conducted by the blood onto the carotids and can sometimes be heard in the interscapular space. The phonocardiogram shows the specific changes in the heart sounds: diminished amplitudes of the first sound at the heart apex and of the second sound over the aorta. Systolic murmur over the aorta is typical; its oscillations are recorded in the form of specific diamondshaped figures.

Diastolic murmur at the second intercostal space by the right edge of a sternum

Diastolic murmur heard over the aorta and at the Botkin-Erb listening point is characteristic of aortic incompetence. This is a low blowing protodiastolic murmur which weakens by the end of diastole as the blood pressure in the aorta drops and the blood-flow rate decreases. The described changes in the sounds and murmurs are clearly visible on PCG in aortic incompetence. The amplitude of the heart sounds and diastolic murmur are decreased on the PCG taken over the aorta.

Systolic murmur at the second intercostal space by the left edge of a breast bone is characteristic of pulmonary artery valves stenosis. The mechanism formation of this murmur is similar to systolic murmur in aortic stenosis.

Diastolic murmur at the second intercostal space by the right edge by the breast bone is characteristic of pulmonary artery valves incompetence. The mechanism formation of this murmur is similar to diastolic murmur in aortic incompetence.

Systolic murmur above the xiphoid process can be heard in tricuspid valve incompetence at the same listening point and also at the 3rd and 4th interspaces, to the right of the sternum; this murmur increases when the patient keeps his breath at the height of inspiration.

Diastolic murmur above the xiphoid process is characteristic of tricuspid stenosis. The mechanism formation of this murmur is similar to diastolic murmur in mitral stenosis.

Extracardial murmurs

Although synchronous with the heart work, they arise outside the heart. These are pericardial and pleuropericardial friction sounds.

Pericardial friction murmurs are connected with the changes in the

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