What is Electrocardiogram / ECG / EKG?

An ECG is a diagnostic test that records the electrical activity of the heart and helps to detect cardiac abnormalities.

Cardiovascular diseases are the number one cause of death all over the world. Interestingly, a number of these deaths can be prevented by simple lifestyle changes like avoiding smoking, increasing physical activity and eating healthy. Several other risk factors like high blood pressure, abnormal lipid levels, diabetes and obesity if treated on time can prevent cardiac problems in the future.


Diagnosis of heart diseases is done with the help of non-invasive as well as invasive tests. Non-invasive tests include:

  • Electrocardiogram (ECG)
  • Echocardiogram
  • Stress test
  • Radiological tests like chest x-ray, CT or MRI

Invasive tests include:

  • Coronary angiogram
  • Pericardiocentesis

The heart is a muscular organ that has valves within it to control the flow of blood. The regular and rhythmic beating of the heart is controlled by two pacemakers, the sinoatrial node and the atrioventricular node. The electrical impulses originate from the SA node and travel to the AV node. Impulses are carried by special conduction tissues throughout the heart thus bringing about controlled contraction of the different parts. This electrical activity also spreads through the body, which is recorded with the help of the ECG leads placed on specific parts of the body.

ECG as a Screening Test

1. Which are the conditions that ECG can be used to diagnose?

ECG is used to diagnose several cardiac problems like abnormalities in the:

  • Cardiac rhythm. These include:
    • Atrial flutter
    • Atrial and ventricular fibrillation
  • Cardiac blood supply. These include:
    • Angina
    • Heart attack
ECG for Heart Attack
    • Cardiac valvular problems
      • Valvular stenosis
      • Valvular regurgitation
    • Cardiac pump failure
      • Right sided heart failure
      • Left sided heart failure
      • Cardiomyopathy

2. How is an ECG performed?

Electrocardiogram (ECG) or "EKG" is a simple non-invasive, painless diagnostic test that records the electrical activity of the heart. It can be done on an outpatient basis with minimal discomfort to the patient. During a resting ECG, the patient lies down flat and 12 electrodes are attached with the help of a gel on the skin of the chest, arms, and legs. The recording is obtained on a screen or graph paper and is analyzed.

3. How is an ECG recording interpreted?

A normal ECG consists of several waves of particular characteristics. Each wave is studied for its length and height to determine any abnormalities. A cardiac cycle consists of P, QRS and T waves. The length of certain intervals is also measured. These include the PR, QT and ST intervals. Abnormalities seen in the measurements may lead to further investigation.

ECG Recording

4. How is a stress test different from an ECG?

During a stress test, an ECG recording is obtained when the person is exercising on a treadmill. Thus, the recording is obtained when the heart is subject to maximum work. The test can detect minor abnormalities in the heart that are not detected on a simple ECG test.

5. What are Holter and event monitors?

Holter and event monitors are small, portable devices that record heart's electrical activity while the patient carries on with normal daily activities. While a Holter monitor records continuously, an event monitor is used to record abnormal heart rhythms.

6. What are the current recommendations regarding the use of ECG as a screening test?

The United States Preventative Services Task Force currently does not recommend routine screening with ECG for people who do not suffer from symptoms of heart disease or are at a low risk for the condition. This is due to the fact that insignificant abnormalities may be detected which could lead to unnecessary further testing, thereby contributing to the inconvenience and financial burden to the patient.

7. What are the benefits of doing an ECG?

An ECG is a simple and non-invasive test that can be used to diagnose cardiac conditions.

8. Are there any harms of doing an ECG for screening purposes?

There are no side effects of the ECG procedure, except may be a minor and temporary rash at the points of contact of the electrodes. However, an ECG may record insignificant changes in the electrical activity of the heart. This may prompt the patient to undergo further tests, which would add to the inconvenience, and increase the mental and financial burden on the patient.

Frequently Asked Questions

1. Where can I get an ECG done?

You can get an ECG done by your general practitioner or health care professional. If there is any abnormality, you may be referred to a cardiac specialist.

2. What are the symptoms that may indicate the need for an ECG?

Symptoms that will require an ECG include:

    • Irregularities in the heart beat, as detected by an irregular pulse
    • Unexplained chest pain, which may indicate angina, heart attack, or inflammation of the sac surrounding the heart
    • Abnormality in cardiac sounds, which may indicate cardiac valvular problem
    • Symptoms of heart failure like breathlessness, leg swelling, weakness and tiredness


  1. Electrocardiogram - (http://www.nhlbi.nih.gov/health/health-topics/topics/ekg/)
  2. Coronary Heart Disease: Screening with Electrocardiography - (http://www.uspreventiveservicestaskforce.org/Page/Document/RecommendationStatementFinal/coronary-heart-disease-screening-with-electrocardiography)

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