Ballistocardiography

ballistocardiogramBallistocardiography - method study contractility of heart muscle by registration of shocks in the body that arise in connection with cardiac activity. The blood in the aorta and the pulmonary trunk accompanied reverse thrust, dedication, transmitted to the body. At registration of movements of the machine (ballistocardiography) is written curve - ballistocardiogram (Fig.), the form of which in heart disease varies.

Ballistocardiography (from the Greek. ballo - throw, to the sword; kardia - heart and grapho - write) - method study of the myocardium contractile function by graphic registration of the mechanical movements of the body caused by heart.
Ballistocardiogram (BCG) healthy man consists of repeated in each of the cardiac cycle waves, which are denoted by the Latin letter H to O (1). Waves H, J, L, N up-directed, waves I, K, M - down. In parallel registration of BCG in dual-channel electrocardiograph wave I observed through 0,04-0,Obsecro R-wave electrocardiogram; it is caused by the initial part of ventricular systole and movement atrioventricular septum in the beginning of isometric phase of ventricular systole. Wave I connected with the period of exile ventricular systolic and reactive drop hearts; wave J, the biggest in amplitude is called a push in the direction of the head, formed by the impact of the jet of blood in the arch of the aorta and the pulmonary artery bifurcation; wave It is connected with the movement of blood through the descending aorta. Waves L, M, N, diastolic, expressed or less regularly.
At BCG has a great influence breath. Segment I - J is incremented when inhaling and decreases during exhalation in norm and especially noticeable changes in heart disease. Changes BCG in connection with breathing became the basis for the creation of a number of classifications of pathological changes BCG. According to the most popular classification brown there are four degrees of pathological changes at BCG (Fig. 2): I degree is the minimum complexes I - J is equal to 40% or less of the maximum amplitude; II - the amplitude of the most part of the complexes is less than half the maximum amplitude; III - the decrease in the amplitude of the waves I-J when inhaling and change their shape during exhalation; IV - curves with irregular chaotic complexes in most parts of cardiac cycles.
On changes BCG when breathing is based calculation ballistocardiography index and respiratory exchange ratio (BI and DK). Ballistocardiography allows you to set the contractile myocardial function in the initial phases of rheumatic process, disorders of coronary circulation, hypertension, atherosclerosis of coronary vessels and other diseases. Ballistocardiography widely used in diagnostic and prognostic purposes, for the evaluation of the functional state of the cardiovascular system. Especially important data is received while conducting functional cardiovascular samples with physical exercise.
The greatest distribution was received ballistocardiography based on immediate registration of the movements with the help of electromagnetic sensor Dock, strengthened on the shins investigated.
Sensor (Fig. 3) is a wooden bar, which includes two series-connected coils 8000 coils of insulated copper wire with cross-section of 0.05-0.08 mm gap between the coils wide 12-14 mm, which introduced a permanent magnet. The magnet is mounted on a tripod from non-magnetic alloy so that, without touching coils, create magnetic field. When the movements of the body, connected with the activity of the heart, in coils occurs induction current which, after passing through the condenser, enters the registering device. Depending on the capacity of the capacitor can be obtained in various recording options. When the condenser 20 MT turns out the so-called diagnostic BCG, when capacitor 2 MF - BCG speed.
For ballistocardiography a photoelectric sensor, based on U-effect (change of the surface tension of mercury during its contact with the electrolyte solution).
When writing BCG under Achilles tendon it is necessary to enclose a piece of wood or a cushion of sand. The entry must occur in a room with solid floors, in a calm environment, in the absence of vibration and other mechanical interference.
For the record BCG indirect method (not received distribution of surveyed stack on ballistocardiography table (Fig. 4) and register fluctuations platform, caused by the movement of his body. Cm. also Cardiography.

Fig. 1. Ballistocardiogram (top) and ECG (bottom) of the healthy person.
Fig. 2. Classification of pathological changes in ballistocardiogram (brown): 1 - the upper limit of normal; 2 - I degree; 3 - II degree; 4 - III degree; 5 - IV degree.
Fig. 3. Electromagnetic sensor Doc: I - view from above; II - side view; 1 - wooden plank; 2 - reel; 3 - stand for lower leg; 4 - tripod for magnet; 5 - magnet; 6 - lead electrocardiograph.
Fig. 4. Ballistocardiography table Starr: 1 - the platform on which lies the subject; 2 - flat steel spring; and - the Foundation of the table; 4 - sensor that converts the movement of the table in pulses of electric current; S cable to the electrocardiograph.