Systolic Murmur

SYSTOLIC MURMUR, a pathological sound phenomenon heard over the area of the heart during the period of ventricular systole. S. murmurs are divided into: 1) organic and 2) non-organic or functional. Organic S. murmurs arise as a result of anatomical changes in the valves or the openings they close. Their occurrence is caused by: 1) either the reverse flow of blood from the ventricles into the atria in case of insufficiency of the mitral or tricuspid valves, or 2) obstacles to the movement of blood from the ventricles into the vessels in case of narrowing of the aortic orifice, resp. pulmonary artery. Organic S. murmurs are best heard in those places where the normal tone corresponding to the given valve is usually heard, in particular in case of mitral valve insufficiency best over the apex of the heart, often however in the III-IV intercostal space to the left of the sternum; in case of tricuspid valve insufficiency - over the lower end of the sternum handle; in case of aortic orifice narrowing - in the II right intercostal space; in case of pulmonary artery orifice narrowing - in the II left intercostal space. However, not all systolic murmurs heard in the II left and right intercostal spaces are caused by narrowing of the aortic orifice, resp. pulmonary artery, in many cases they are caused by expansion of the initial part of the aorta, resp. pulmonary artery, unevenness of their intima or uneven thickening of their walls, for example as a result of their sclerosis. Organic murmurs are usually well conducted along the blood flow - in case of mitral and tricuspid valve insufficiency upward, into the axillary regions, in case of aortic narrowing - upward into the aorta and neck vessels, in case of pulmonary artery narrowing - toward the left clavicle. The Russian school classifies as functional, or non-organic S. murmurs all murmurs that occur in the absence of anatomical changes in the heart valves or the openings they close, while the French school distinguishes between the concepts: functional and non-organic S. murmurs. French authors classify as functional murmurs those caused by relative insufficiency of the valve apparatus due to expansion of the atrioventricular ring in case of heart muscle lesions. Non-organic murmurs, however, they classify as murmurs that occur both in the absence of valve changes and in the absence of anatomical changes in the myocardium. This group includes murmurs of the most diverse origins, such as murmurs heard in anemias (circular and vortex movements of blood caused by increased blood flow velocity and decreased viscosity), in high position of the diaphragm due to meteorism, pregnancy, etc. [relative pulmonary artery stenosis (?)], in older children [discrepancy between the width of the pulmonary artery lumen and the size of the right ventricle (?)], etc. All these murmurs are usually heard most often over the apex of the heart or over all heart openings, also most intensely over the pulmonary artery. Various theories have been proposed to explain the origin of non-organic S. murmurs. According to the old theory of Potain, all non-organic murmurs arise extracardially, in the lungs, being cardio-pulmonary murmurs. Their occurrence is caused by the fact that during systole the heart decreases in volume, and the space freed up as a result is filled by the expanding edge of the lung, into which air is drawn, producing a noise synchronous with cardiac systole. According to the view of Luthe, non-organic S. murmurs arise as a result of relative pulmonary artery stenosis, as is particularly often the case in older children, in whom S. murmur over the pulmonary artery is almost a physiological phenomenon. The theory of Salle gained greatest popularity at the time, according to which non-organic murmurs, being endocardial murmurs, depend on acceleration of blood flow and changes in its physicochemical state. This explanation is apparently correct, as observations of blood flow velocity show for most S. murmurs heard over the pulmonary artery in anemias, especially of the chlorotic type, in thyrotoxicosis, in easily excitable people, etc. In the great majority of cases, however, as daily clinical observations show, such murmurs, especially when heard at the apex, are associated with a certain pathological condition of the neuromuscular apparatus of the heart, and their pathogenesis is the same as that of S. murmurs of muscular origin, i.e., they are caused by relative insufficiency of the valves. Therefore, the division of S. murmurs into non-organic and functional is hardly correct. In the great majority of cases, functional murmurs are caused by weakening of the contractile and tonic function of the myocardium, in particular of all the musculature of the ventricles or only of the circular muscle fibers of the atrioventricular opening or of the papillary musculature. This most often occurs in acute infectious diseases, such as typhoid, pneumonia, acute rheumatism, etc., often giving rise to the erroneous attribution of these murmurs to endocardial lesions. The category of functional-muscular origin murmurs should apparently also include most S. murmurs in thyrotoxicosis, in pronounced anemias and cachexia, especially in cases when these murmurs are heard at the apex of the heart (murmurs heard over the pulmonary artery are apparently mainly caused by acceleration of blood flow present in these diseases), as well as in persons with an overexcited nervous system, with general nutritional decline, general weakness, etc., which particularly often occurs in adolescence and in women, in whom, especially in the recumbent position, S. murmurs are very often heard. The significance of the tonic and contractile function of the myocardium for the occurrence of functional S. murmurs in these cases is proved by the fact that with increased tone of the cardiac muscle (when using strychnine, hydrotherapeutic procedures, mototherapy, etc.) these murmurs often noticeably weaken or disappear. - Some authors (Savitsky, Tregubov, Mikhailov and Popov) attribute special importance in the origin of functional S. murmurs to the increase and decrease in tone of the papillary muscles, caused by disturbance of the balance of tone of the autonomic nervous system. According to these views, with weakening of the papillary muscles, the mitral valve during systole of the left ventricle turns inside out toward the atrium, which causes reverse blood flow from the ventricle into the atrium and the appearance of S. murmur. With hypertonia of the papillary muscles, the valve does not completely close the atrioventricular opening, which also leads to the appearance of S. murmur. It is necessary however to point out that the question of the significance of hyper- and hypotonia of the papillary muscles for the occurrence of functional S. murmurs cannot at the present time be considered finally resolved, since the evidence brought by authors in favor of this position, in particular pharmacological tests with adrenaline and atropine, are not convincing. S. murmurs heard over the area of the heart can be of different character, have different pitch and strength, can be of different duration, be conducted differently and change depending on the change in body position and the phase of respiration. These features are usually used, on the one hand, to determine the place of origin of the murmur, and on the other - for differential diagnosis between organic and functional S. murmurs. By character, S. murmurs are distinguished as rough, gentle, blowing, scraping, sawing, buzzing, musical, etc. The strength of the murmur varies - they can barely be perceived and be very loud, sharp. They are usually most pronounced at the very beginning and more or less quickly weaken toward the end of systole (decrescendo), which is caused by the decrease in pressure difference between the ventricles and the aorta, resp. pulmonary artery, or the atria as the ventricles empty and these vessels, resp. atria, fill. Basically the strength of the murmur is determined by the degree of narrowing or insufficiency, the speed of blood flow, the degree of