Electrocardiogram (ECG)


An electrocardiogram is a test that checks for problems with the electrical activity of your heart and checks your heart’s rhythm. An ECG translates the heart's electrical activity into line tracings on paper. The spikes and dips in the line tracings are called waves. A natural electrical system causes the heart muscle to contract and pump blood through the heart to the lungs and the rest of the body.

An electrocardiogram (ECG) is done to:
  • Check the heart's electrical activity.
  • Find the cause of unexplained chest pain.
  • Find the cause of symptoms of heart disease.
  • Find out if the walls of the heart chambers are too thick (hypertrophied).
  • Check how well medicines are working and whether they are causing side effects that affect the heart.
  • Check how well mechanical devices that are implanted in the heart.
  • Check the health of the heart when other diseases or conditions are present.


Sensors attached to the skin are used to detect the electrical signals produced by your heart each time it beats. These signals are recorded by a machine and are looked at by a doctor to see if they're unusual. An ECG may be requested by a cardiologist.

When an ECG is used:

An ECG is often used alongside other tests to help diagnose and monitor conditions affecting the heart. It can be used to investigate symptoms of a possible heart problem, such as chest pain, suddenly noticeable heartbeats (palpitations), dizziness and shortness of breath.

An ECG can help detect:

  • Arrhythmias - where the heart beats too slowly, too quickly, or irregularly.
  • Coronary heart disease - where the heart's blood supply is blocked or interrupted by a build-up of fatty substances.
  • Heart attacks - where the supply of blood to the heart is suddenly blocked.
  • Cardiomyopathy - where the heart walls become thickened or enlarged A series of ECGs can also be taken over time to monitor a person already diagnosed with a heart condition or taking medication known to potentially affect the heart.

How an ECG is carried out?
There are several different ways an ECG can be carried out. Generally, the test involves attaching a number of small, sticky sensors called electrodes to your arms, legs and chest. These are connected by wires to an ECG recording machine.

You don't need to do anything special to prepare for the test. You can eat and drink as normal beforehand. The test itself will normally only last a few minutes, and you can usually go home soon afterwards or return to the ward if you're already staying in hospital.

Are there any risks or side effects?
An ECG is a quick, safe and painless test. No electricity is put into your body while it's carried out. There may be some slight discomfort when the electrodes are removed from your skin – similar to removing a sticking plaster – and some people may develop a mild rash where the electrodes were attached. In case you feel stress or chest pain during the test, it can be stopped.