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You are in: Home > Heart Information > Tests > Electrocardiogram (ECG)

Electrocardiogram (ECG)

• ECG
• 24 hour ECG
• Exercise ECG

ECG

ECG stands for electrocardiogram, which gives a recording of the electrical activity of the heart in the form of a graph (see diagram for an example of an ECG recording).

An ECG recording consists of 'waves' and 'complexes' which correspond to particular phases in the heart's electrical cycle. These are identified by the letters P, Q, R, S and T.

Electrodes, attached to sticky patches, are positioned on your chest, wrists and ankles and a recording of the electrical signal between the electrodes is made.

ECGs are often referred to by the number of 'leads' e.g. 12 lead ECG. Each lead gives a view of the electrical activity of the heart from a particular angle across the body (i.e. between two electrodes) .

The ECG reflects what is happening in different areas of the heart and helps to show up any abnormality in the conducting system.

An ECG is painless and the procedure usually takes about 5–10 minutes.

24 hour ECG

This is sometimes referred to as an ambulatory ECG. In this test there are fewer electrodes than a standard ECG.

These electrodes are connected to a small box (similar in size to an original personal stereo system) and attached to a belt which you wear for 24 hours, as you go about your normal daily activities.

A 24hr ECG records the information on a tape, which can then be studied by your doctor. This can be very helpful in looking at irregular heart rhythms that come and go. It can also be used to confirm whether or not symptoms you are having are related to your heart.

Exercise ECG

Also known as a 'stress test' or 'treadmill test'. This is a type of ECG which records the activity of the heart as you make it work harder i.e. by walking and talking on a treadmill.

You will be closely monitored by medical staff during this test. An exercise ECG records changes that the heart experiences due to an insufficient blood supply.

It can be used to diagnose angina and assess its severity. Not everyone will be able or fit enough to have this test.

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