In order for the heart muscle to pump as regularly as possible year in and year out, pulses are sent out by a pacemaker. These electrical activities can be recorded with electrocardiography. Its pattern provides information about heart function, rhythm and expired infarcts. After 70 years of age, the heart has contracted about 3 billion times and relaxed again, pumping around 7, 000 liters of blood daily through the body. In order to achieve this performance, a stimulus is generated by the so-called sinus node 60- to 70-times per minute in the healthy at rest, which spreads as electrical current through certain pathways to the heart muscle and these animated to pump. The sinus node is a network of specialized cardiomyocytes in the right atrium of the heart and controls the heart rate, thus serving as a natural pacemaker. The heart motivates itself constantly to work.
The ECG - how does it work?
Since the human body conducts current, this excitation spread in the heart can be recorded in a graph. For this purpose, a plurality of metal plates are attached as electrodes at certain intervals on the body surface and derived the intermediate voltage fluctuations (electrical potentials). They are amplified in the ECG device and displayed or printed on the monitor. As the electrical impulse changes direction in its course, the graph (electrocardiogram) also varies depending on the time of the action. The entire process that follows is repeated at every heartbeat. Tissue changes as z. B. occur after a heart attack, lead to the diversion of the currents and thus to typical deviations.
What for the layman at best looks like line drawings of mountains and valleys, gives the expert valuable information about the heart action. In addition to the rhythm, ie the frequency and regularity of the voltage changes, their size, direction and duration are also evaluated. Thus, disorders of arousal formation, spread and regressions in the conduction system and in the heart muscle can be determined and the position of the heart in the chest determined.