From Big Medical Encyclopedia

SEISMOCARDIOGRAPHY (Greek seismos fluctuation, an earthquake + a cardiography) — the method of registration of mechanical oscillations (vibrations) of a chest wall connected with action of the heart, used for studying of force of cordial reductions and the phase analysis of a cardial cycle. Frequency range of the registered fluctuations lies within 0,1 — 60 Hz. By means of S. register a second or third derivative shifts of a chest wall. By the principle C. it is closest to kinetokardiografiya (see), apekskardiografiya (see. Cardiography ) and dorsoventral ballistokardiografiya (see).

Sensors for registration of the seismocardiogram (SKG) represent the accelerometers which are directly contacting to a chest wall. The less mass of the sensor, the less amplitude-phase distortions is brought in record. The most adequate is registration of SKG by means of the piezoelectric accelerometer. The mechanical oscillations of a chest wall registered at the same time correspond to the frequency range of 5 — 40 Hz with a maximum apprx. 20 Hz.

SKG can be registered in provisions inspected lying, sitting, standing. Sensor (see) fix an elastic rubber tape or a special belt. Most often it have over the lower third of a breast, but also other points can be chosen. The maximum amplitude of SKG is noted at an arrangement of the sensor in a breast on the left parasternal line or in points of a projection of the ascending aorta.

Synchronously registered electrocardiogram (a) and the seismocardiogram (b) are normal: A0 — an atrial wave, A1 — a systolic cycle of fluctuations, A2 — a diastolic cycle of fluctuations, A3 — an additional oscillatory cycle in a diastole.

In the drawing SKG and ECGs registered at the same time are presented. At almost healthy people on SKG distinguish two basis oscillatory cycles connected with reduction of ventricles of heart — systolic (A1) and diastolic (A2), sometimes the third additional oscillatory cycle in a diastole (A3), and also atrial fluctuations (A0) - At the expressed asynchronism of reductions of the right and left auricles the A0 complex can consist of two waves. The oscillatory cycle A1 begins in a phase of izometrrkhchesky reduction of ventricles and reaches a maximum at the beginning of a phase of bystry exile. Duration of this cycle depends on co-ordination of reductions of the right and left ventricles of heart. The cycle A2 arises at the beginning of a diastole and is caused by a relaxation of ventricles and a reversed current of blood in an aorta. Between the oscillatory cycles A1 and A2 the so-called waves of exile caused by fluctuations of a chest wall during exile of blood ventricles are noted. The third oscillatory cycle (A3), apparently, is connected with hydraulic forces during the movement of blood from auricles in ventricles in a phase of bystry filling.

In the analysis of SKG measure amplitudes of the cycles A1 and A2 and their ratio, duration of a mechanical systole of A1A2 and other indicators. Amplitude and a form of oscillatory cycles SKG change according to phases of breath. On a breath amplitude of cycles increases a little, their duration decreases that is caused by changes of inflow of blood and filling of cavities of ventricles. Amplitude of the cycle A1 depends on rate of pressure rise in ventricles and reflects force of cordial reduction therefore its size allows to judge sokratitelny function of heart. Criteria for assessment of degree of a deviation of SKG from norm are offered: The I degree — existence of considerable respiratory fluctuations of amplitude of cycles SKG; II extent existence of changes of the SKG form, emergence of big waves of A0 or cycles A3, expansion of oscillatory cycles; The III degree — considerable expansion of the cycle A1 up to merge to the cycle A2 or considerable reduction of amplitude of cycles; The IV degree — very low-voltage SKG or a chaotic, nondifferentiable curve.

One of the first ranges of application of S. was the space medicine (see. Meditsina space ). Even during the first piloted flights by the East and Rising ships changes of force of cordial reductions at astronauts at different stages of adaptation to conditions of zero gravity were studied. In the subsequent this method began to be applied constantly in system of medical control by the ships «Union» and at the Salute space stations. Apply S. and in sports medicine. S.'s use in a wedge, showed to practice, - that this method allows to reveal the changes of sokratitelny ability of heart caused by both organic lesions, and functional shifts. On the basis of the analysis of changes of SKG at various arrhythmias it is possible to receive the objective characteristic of extent of disturbance hemodynamics (see). Villages use also at mass inspections of the population.

Bibliography: Anishkina N. M., etc. Piesoceramic Pulse sensor, Medical equipment, No. 1. page 29, 1978; Bai-with to and y R. M. Forecasting of states on the verge of norm and pathology, M., 1979; Children's sports medicine, under the editorship of S. B. Tikhvinsky and S. V. Khrushchev, M., 1§80; Parin V. V., etc. Space cardiology, D., 1967; Fetisov N. S. Use of a seismocardiography at rheumatic damages of heart, in book: Vopr. cybernetics, under the editorship of S. I. Samoylenko, etc., century 22, page 140, M., 1976.

R. M. Bayevsky.