Methods of investigation of cardiac activity
The size of the heart are determined by chest percussion (percussion). When tapping on the finger, attached to the chest above the heart, it turns dull sound. The exact size of the heart are determined by radiography of the chest wall X-rays (radiographs).
The size of the heart change under tension. They depend on the thickness of his muscles.
In a healthy person are heard two tones of the heart. Listening tones called auscultation.
The first heart sound (systolic) – dull, low and drawling. He listened at the top, at the level of the fifth left intercostal space, on the finger inwards from the nipple line. This tone is caused by slamming three and bivalve valves and swing attached to them filaments and muscle contraction of the ventricles. It occurs at the beginning of ventricular systole and lasts for about 0.12 seconds.
The second heart sound (diastolic) – a clear, tall and short. He listened at the second intercostal space at the sternum. This tone is caused by slamming semilunar valves at the end of ventricular systole and lasts for about 0.08 seconds.
Cardiac impulse and cardiography
During ventricular systole the heart changes its position in the chest. Its base is slightly lowered down, the heart is rotated slightly larger vessels from left to right, his muscles tense and the tip of the heart strikes the chest in the fifth intercostal space on the finger inwards from the nipple line, bulging chest wall. It is felt as a protrusion of the push. In full swing wall people barely noticeable. It can be clearly seen from the lean.
Recording of vibrations caused by the heart, called a cardiogram. It is very similar to the recording of intracardiac pressure.
Currents action of the heart and ECG
Currents action of the heart have a very low voltage, measured in hundredths or thousandths of a volt, and captured by special instruments with which they can be written. This entry is designated as an electrocardiogram.
Since the heart is located in the thorax asymmetrically, the current lines emanating from the base of the heart, are transferred to the right hand, and coming from the apex of the heart – the left arm.
Apply three diversion action currents of the heart:
- 1) from the right and left hand, 2) on the right hand and left foot, 3) of the left hand and left foot.
If you simultaneously record current action of the heart and the pressure in the cavities of the heart, we can determine what phase of the heart correspond to the teeth. P wave is associated with atrial systole, and the teeth Q; R; S; T – with ventricular systole.
AF Samoilov found that an electrocardiogram depends on the personality of the body, the size and position of the heart in the chest and on its functional state.
To register for heart bioelectric potentials at large distances apply teleelektrokardiografy.
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