EKG (Electrocardiogram)

In order for the heart muscle to pump as regularly as possible, impulses are sent out by a pacemaker. These electrical activities can be recorded with electrocardiography or an electrocardiogram. Their pattern provides information about heart function, rhythm and previous infarctions. By the age of 70, the heart has contracted and relaxed about 3 billion times to pump about 7,000 liters of blood through the body every day. In order to achieve this performance, a stimulus is generated by the so-called sinus node in healthy people at rest 60 to 70 times per minute, which spreads as an electric current through certain pathways to the heart muscles and encourages them to pump. The sinus node is a network of specialized heart muscle cells in the right atrium of the heart and controls the heart rate, thus serves as a natural pacemaker. The heart This constantly motivates  himself to work.

The ECG – how does an electrocardiogram work?

Since the human body conducts electricity, this spread of excitation in the heart can be plotted on a graph. For this purpose, several metal plates are attached to the body surface as electrodes at certain intervals and the voltage fluctuations (electrical potentials) between them are derived. They are amplified in the ECG device and displayed on the monitor or printed out.

Because the electrical impulse changes direction as it progresses, the waveform (electrocardiogram) also varies depending on the timing of the action. The entire resulting sequence is repeated with every heartbeat. Tissue changes such as B. occur after a  heart attack  , lead to the diversion of currents and thus to typical deviations.

What looks at best like line drawings of mountains and valleys to the layman gives experts valuable information about the heart’s action. In addition to the rhythm, i.e. the frequency and regularity of the voltage changes, their size, direction and duration are also evaluated. In this way, disturbances in the generation, propagation and regression of excitation in the conduction system and in the cardiac muscles can be determined and the position of the heart in the chest can be determined.

When to use the ECG

Since the normal ECG is risk-free for the resting patient, it is carried out as a routine examination if heart disease is suspected. Can be recognized:

  • Circulatory disorders (diseases of the coronary arteries, heart attack)
  • Cardiac arrhythmias  (heartbeat too fast, too slow or irregular, atrial fibrillation/flutter, ventricular fibrillation/flutter)
  • drug overdose
  • Mineral deficiency or excess (e.g.  potassium )
  • Inflammation  of the heart muscle or pericardium

The ECG is also used to monitor the course and therapy of heart diseases. Some lung diseases (e.g. embolism) also lead to changes in the ECG. Before and during an  operation  , it is an essential part of diagnostics to check the patient’s heart function.

How is the examination performed?

If the  patient is taking medication  , they should tell the examiner beforehand. Heart medication in particular can change the ECG and otherwise lead to incorrect diagnoses.

In order to obtain evaluable results, the electrodes are always attached in a specific order to defined locations on the chest (chest wall leads V1-V6) and the wrists and ankles (extremity leads). In order to increase their conductivity, a gel can be used with suction electrodes and the electrode paper can be moistened; if there is a lot of hair on the chest, a partial shave may be necessary. The electrodes are connected to the ECG machine with a cable.

There are different types of electrocardiograms:

  • With the  resting ECG  – the “basic form” – the patient lies quiet and relaxed during the measurement.
  • Some changes, such as circulatory or arrhythmia disorders, only become apparent under physical stress; in such cases, a  stress ECG (ergometry) displayed on the bike or treadmill. The load is increased in a controlled manner in several steps up to “load” (highest load level, which depends, among other things, on age and gender) or until symptoms or serious ECG changes occur. In addition to the cardiac current curve, blood pressure and pulse are also measured. Ergometry is also used, among other things, when there is a suspicion of high exertion pressure, for therapy control and to clarify the resilience after a heart attack or after heart operations. Since complications such as heart pain or even an infarction can occur, ergometry is always carried out under medical supervision.
  • If there is a suspicion of cardiac arrhythmias, a  long-term ECG  may be indicated. The person concerned carries a small recording device with them 24 hours a day and notes activities and complaints. Diseases of the coronary arteries and the control of a pacemaker are also areas of application for the long-term ECG.
  • Special forms such as the  intracardiac ECG  (during a heart catheter examination) or  esophageal ECG  are reserved for specific questions.


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