What an electrocardiogram is used for

Also called an ECG or EKG, it can help investigate chest discomfort, palpitations, breathlessness, dizziness or fainting. Clinicians also use it when monitoring known heart conditions, certain medicines, or changes in a person's clinical condition.

Sticky electrodes placed on the skin detect electrical signals from different directions. The tracing can reveal an irregular rhythm such as atrial fibrillation, conduction delays, or patterns that support further assessment for reduced blood flow or heart muscle changes. A normal tracing captures only that recording period and does not exclude every intermittent rhythm problem or heart condition.

Wear clothing that allows access to your chest, wrists and ankles, and avoid applying oily lotion to those areas beforehand because it can stop electrodes sticking. Tell the clinician about your symptoms, medicines and implanted cardiac devices. During a resting ECG, lie still and breathe normally while the machine records; the electrodes detect signals and do not deliver electricity into your body.

Do not wait for a routine ECG appointment if you have severe or persistent chest pressure, sudden marked breathlessness, collapse, or fainting with ongoing symptoms; seek emergency help. Palpitations accompanied by chest pain, severe dizziness or near-fainting also need urgent assessment. The need for urgent care comes from the symptoms, not from whether an earlier ECG was normal.

Ask what question the ECG is intended to answer, whether the result explains your symptoms, and whether comparison with an earlier tracing is useful. If symptoms come and go, ask whether longer rhythm monitoring or another test is appropriate and what to do if an episode returns.