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Electrocardiogram (ECG)

Last updated date: 17th May 2024
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What is Electrocardiogram (ECG)?

A simple, painless test that measures the heart's electrical activity is termed as an electrocardiogram. It's also known as an ECG or EKG. In this, every heartbeat is triggered by an electrical signal that starts at the top of the heart and travels to the bottom. Generally. heart problems often affect the electrical activity of the heart. In other words,  an electrocardiogram is a graphic record produced by an electrocardiograph that provides details about one’s heart rate and rhythm and depicts if the heart has enlarged due to hypertension (high blood pressure) or evidence of a myocardial infarction previously (heart attack if any). 

It is one of the most common and effective tests in all drugs. We use electrocardiogram because it is easy to perform, non-invasive, yields outcomes instantly, and can identify hundreds of heart conditions. 

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Why Is It Done?

Two kinds of data are given by an ECG. First, a surgeon will determine how long it takes for the electromagnetic pulse to travel through the heart by calculating time intervals on the ECG. He observes that whether the electrical activity is natural or sluggish, fast or erratic, figuring out how long a pulse takes to travel from one part of the heart to the next. Second, it may help a cardiologist to find out if areas of the heart are too large or overworked by measuring the amount of electrical activity that flows through the heart muscle. 

In this process, ten electrodes are mounted on the arms of the patient and the top of the heart in a traditional 12-lead ECG. We calculate the average strength of the electrical potential of the heart from these 12 leads and report over a period of time (generally it is 10 seconds). The total intensity and trajectory of the electrical depolarization of the heart are observed at each moment, throughout the cardiac phase.

Doctors do not use ECG as an attempt for prevention among those without symptoms or at low risk of cardiovascular disease because an ECG may incorrectly suggest a concern. It also leads to misdiagnosis, initiation for invasive procedures, or overtreatment. Those individuals who are working in some sensitive professions, such as aeroplane pilots, may need to have an ECG as part of their routine safety evaluations.

The main objective of an ECG is to obtain information about the heart’s electrical function. An ECG is used to measure:

  • Any heart damage and weaknesses in various parts of the heart muscle

  • The beating of the heart is observed whether it normally beats

  • The effects of drugs or devices used to control your heart (such as a pacemaker)

  • Helps to check the size and position of the heart chambers

  • Used to diagnose abnormal heart rhythms

Mechanism of ECG

The indirect proof of blood flowing to the muscle of the heart along with measuring the rhythm and rate of heartbeat is shown by an ECG. For the tool to have a routine working, a standardized system has been developed for placing the electrode. We require 10 electrodes for the heart to view electrical impulses at least 12 in number.  A lead of an electrode is kept on every arm and leg with the wall of the chest with six of them. The signals originating from every electrode is recorded by a machine and it is shown in a printed format as an electrocardiograph.


The electrodes which measure the electric impulses that come from various parts around the heart are fixed on various body parts.  Every electrode has normal patterns. Abnormal patterns would be the symptoms with the person having different heart disorders. Using ECG, one could detect different disorders like:

  • Heart Attack: 

Abnormal patterns of heartbeats would help to detect these irregularities. A heart attack damages the muscles of the heart and the scar tissue is healed simultaneously.

  • Enlarged Heart: 

In this case, the impulses would be larger instead of normal ones.

  • Abnormal Heart Rhythms: 

In ECG, we observe abnormal heart rhythms particularly in case of heart rates which are very slow or very fast or irregular in a particular person.

What Does Abnormal Rhythm Mean?

The abnormal results would be the result of the following defects:

  • It may be heart enlargement.

  • It may be a heart attack (previous or present).

  • It may be arteries with poor blood supply.

  • It may be a heart defect (congenital).

  • It may be muscle damage to the heart.

  • It may be fluctuations in electrolyte content (like calcium and potassium) in the blood.

  • It may be swelling around the covering around the heart.

  • It may be fluid or swelling in the sac around the heart.

It should be noted that the accuracy of the result would be dependent on the conditions in which the test was conducted. Every problem of the heart would not be traced using ECG because there are certain heart conditions which do not show any particular changes in the test results.


Did You Know?

  • An ECG is the same thing as an EKG but when it is translated into the German language, the word electrocardiogram is spelt Elektro-kardiographie. EKG is just the way to say ECG based on the translation.

  • Every day, our heart pumps about 2,000 gallons of blood.

  • There are no side effects of ECG.

  •  An ECG won't hurt at all during or after the test.

  • All testing takes place on the outside of the body and it does not hurt.

FAQs on Electrocardiogram (ECG)

1. What is a Pacemaker?

Ans: A pacemaker is a small self-contained metal box containing a battery, circuits, and connections for wires. These are passed down through veins under the collar-bone under local anaesthetic, guided by X-rays.

2. What is the Difference Between ECG and Echocardiogram?

Ans: The Echocardiogram and Electrocardiogram are both diagnostic tests. The difference between them is the instrument and methodology used. An ECG uses electrical impulses to read the heart’s rhythm and activity, while the Echocardiogram uses ultrasound technology to produce an image of the heart.