Presystolic Murmur

PRESYSTOLIC MURMUR, a sound heard over the heart at the end of diastole—in the presystole. This murmur is observed primarily in cases of narrowing of the atrioventricular openings, mainly in the much more frequently occurring narrowing of the left atrioventricular opening (stenosis mitralis). This murmur is coarse, has a vibrating character, and, according to Laënnec, resembles the sound of sawing wood. The duration of the murmur is variable, but it is usually short, the intensity of the murmur gradually increases (crescendo character), and it is abruptly terminated by the accentuated first heart sound. The murmur is usually heard over a very limited area, sometimes not exceeding 2 cm, and in cases of narrowing of the left atrioventricular opening, it is heard at the apex of the heart and between the apex and the left edge of the sternum, while in cases of narrowing of the right atrioventricular opening, it is heard at the xiphoid process of the sternum. At present, it can be considered established that the P. murmur is caused by blood passing through the narrowed atrioventricular opening during the contraction phase of the atria. When the pressure in the atria exceeds the pressure in the ventricles, the atrioventricular valves open, and ventricular filling begins. During diastole, the rate of blood flow through the atrioventricular openings gradually decreases as the intraventricular pressure rises. Only at the end of diastole, when the difference between intra-atrial and intraventricular pressure increases again due to atrial contraction, the rate of blood flow through the atrioventricular openings increases again. Thus, diastole of the cardiac cycle has two periods with the highest rate of blood flow through the atrioventricular opening: one at the beginning of diastole immediately after closure of the semilunar valves, and the other at the end of diastole at the moment of atrial contraction (Lewis). Acceleration of blood flow contributes to the appearance of the murmur. In severe narrowing, in addition to the P. murmur, a murmur sometimes appears at the beginning of diastole immediately after opening of the atrioventricular valves. In cases of marked narrowing and increased rate of blood flow through the atrioventricular openings, the murmur fills the entire diastole. The main factor in the appearance of the P. murmur is atrial contraction; even Mackenzie made the observation that when atrial fibrillation occurs, when the atria as a whole cease to contract, the P. murmur disappears. The disappearance of the P. murmur in cases of narrowing of the atrioventricular openings is thus one of the signs of the onset of atrial fibrillation. When in cases of narrowing of the atrioventricular openings the atrioventricular interval is prolonged, the P. murmur does not end, as usual, with the first heart sound, but an interval appears between the sound and the murmur. With simultaneous recording of phonocardiogram and electrocardiogram, it was also established that the P. murmur coincides with atrial contraction. A number of English clinicians, in particular Brockbank, have put forward the theory that the murmur in narrowing of the left atrioventricular opening, classified as presystolic, is essentially systolic. According to them, this murmur occurs during systole in the tension phase and is caused by the fact that the altered atrioventricular valves do not close immediately and allow blood to pass through; atrial contraction thus, according to Brockbank's opinion, plays no role in the occurrence of the P. murmur. This theory can be considered refuted on the basis of all the above. - The P. murmur is occasionally observed in cases of insufficiency of the aortic valves. This was first noted by Flint (1860). Flint explains the occurrence of the P. murmur by the fact that the reverse flow of blood from the aorta presses on the leaflets of the left atrioventricular valve and thus, at the moment of atrial contraction, there is relative narrowing of the opening. This narrowing of the left atrioventricular opening is caused (Zimnitsky, Elias) by the displacement of the aortic valve leaflet, which can undergo anatomical changes from constant impact of the diastolic wave. Thus, in cases of aortic valve insufficiency, non-functional, rather than organic, narrowing of the left atrioventricular opening can occur. It should be noted that the character of Flint's murmur compared to the P. murmur in narrowing of the atrioventricular openings is significantly less coarse and harsh. As a great rarity, the P. murmur has been observed in adhesive pericarditis in children.

L. Fogelson. PRESS Aleksey Aleksandrovich (1857-1930), a major worker in the field of safety engineering, one of the founders of the struggle with industrial trauma along the line of technical protection of labor in Russia. After graduating in 1879 from the St. Petersburg Polytechnic Institute, P. in 1883 published a fundamental monograph in 8 issues devoted to labor protection and safety engineering. Soon he began working in the Ministry of Trade and Industry on issues of technical protection of labor. He was the organizer and chief editor of the multi-volume collective work 'Protection of the life and health of workers in industry' (parts 1-3, P., 1913-17), published by the ministry of trade and industry, which was a handbook for many practical workers in the field of labor protection in pre-revolutionary and in the first years after the October Revolution. In addition, during these years he worked extensively in the field of vocational and technical education. In 1912, he was one of the organizers of the polytechnic institute in Yekaterinoslav, in 1916 he was elected professor of mechanical technology at Yekaterinoslav. In 1915 he began to head the technical department of the St. Petersburg Insurance Partnership, where he worked until its liquidation in the first years after the October Revolution. After this (1918) P. immediately moved to work in the Leningrad Regional Department of Labor, where he worked on issues of social insurance and labor protection. From 1925, leaving direct work in the Department of Labor due to his advanced age, P. devoted himself entirely to pedagogical and literary activity, mainly again on issues of safety engineering (as well as on issues of social insurance). P. was an active propagandist of the idea of creating a new specialty—social engineering, combining issues of professional hygiene, sanitary engineering, and safety engineering. In 1920, P. organized in the composition of the Leningrad Polytechnic Institute a faculty of social engineering and was elected professor of preventive engineering there. In 1925, P. was entrusted by the NKT USSR with editing a series of monographs on safety engineering under the general title 'Safety in Labor.' Before his death, Press managed to publish 13 issues of this series (some of them went through three editions) and to edit several more issues. Press was a member of the editorial board of the journal 'Hygiene of Labor,' a lifelong honorary member of the Scientific-Consultative Section of the Leningrad Department of Labor, an honorary member of the Central Institute for Labor Protection, a member of numerous scientific and scientific-public organizations. To P. belong up to 10 monographs and up to 100 journal articles, as well as numerous newspaper articles, especially in the post-revolutionary years, propagandizing ideas of labor protection. The main works of P.: 'Devices for the protection of the life and health of workers when handling machines for wood processing' (Notes of the Russian Technical Society, SPB, 1883); 'Protection of the life and health of workers in factories and plants' (parts 1-3, SPB, 1892); 'Social Engineering' (P., 1918); 'Classification of labor by degree of safety and harmfulness' (P., 1919). Under the editorship of P. (the series of monographs on safety engineering 'Safety in Labor' was published (issues 1-18, M., 1927-32; some issues were reprinted); in this series, P. as author belongs monographs on mechanical wood processing and on transmissions.