What the Electrocardiography (ECG) machine?

Electrocardiography (ECG) a method of recording or graphic tracing the heart activity with the help of electrodes placed on the skin in order to determine its healthy functioning conditions.


These electrodes usually detect the very minute form of changes in an electrical path on the skin which arises from the heart muscles and the electrophysiologic patterns of the depolarizing during every heartbeat.

The human heart is an unique organ, which produces an electrical impulse by itself. As this electrical impulse passes through our heart, it generates an electrical current that spreads over our body and reaches the skin.

The patient is connected to the Electrocardiography (ECG) machine with three electrical leads (one each to both wrists and the third to the left ankle of the patient), that is used to monitor the activity of the heart. This is standard ECG testing. Of course, detailed ones do exist, involving multiple leads to the patient’s chest.


P to T in the graph represents a specific activity of the heart. Let’s break it down.

  • The P wave is the electrical excitation of the atria, or depolarization, initiating atrial contraction.
  • The QRS complex is the depolarization of ventricles, initiating ventricular contraction. Marking the beginning of the systole.
  • T wave means the return of ventricles to the normal state (repolarization). Marking the end of the systole.

By counting the number of QRS complexes we can evaluate the heartbeat rate of the patient.

Any deviations in this shape results in heart diseases or an abnormal heart rhythm which can either be slow, irregular or very fast heartbeats. Hence it is an essential equipment in the field of medicine.

For more detailed information about Electrocardiograph (ECG), visit Byju’s

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