What should you know about an electrocardiogram test?

A clinician places adhesive electrodes on the chest and sometimes the arms and legs. Wires connect them to an ECG machine, which turns the signals into a tracing. You usually lie still and breathe normally while the recording is taken. The test does not send electricity into your body.

The tracing can show the rate and regularity of the heartbeat and patterns that may need further assessment. The meaning depends on your symptoms, examination and health history, so a printed line should be reviewed by a qualified clinician.

Wear clothing that can be adjusted for access to the chest, and mention allergies to adhesives or difficulty lying flat. Avoid applying oily creams to electrode areas unless your clinic advises otherwise. Keep still during the recording; movement, shivering or talking can create interference and may require another recording.

Call emergency services for new or severe chest pain, major breathlessness, fainting, collapse or sudden weakness. Do not wait for a routine ECG appointment when these symptoms are happening. Arrange a review for recurring racing beats, unexplained dizziness or reduced ability to exercise.

Ask why the test is recommended, whether you need to change any medicines, when results will be available and whether further testing may be needed.