Welch Allyn twelve-lead ECG machine

During an ECG, adhesive electrodes are placed on the chest and limbs. The machine detects tiny electrical signals as the heart contracts and displays them as waveforms on a printout or screen. Twelve views of the heart’s electrical activity help a trained clinician look for rhythm disturbances, conduction changes or patterns that may need further assessment.

The device records information; it does not by itself provide a complete diagnosis. Movement, loose electrodes, muscle tension or interference can affect the tracing. A clinician interprets the recording alongside symptoms, examination findings and medical history.

Wear clothing that allows access to the chest and lower limbs. Tell the clinician about chest discomfort, palpitations, breathlessness, dizziness, implanted cardiac devices and medicines. Remain still and breathe normally during the brief recording. The electrodes may feel cool when applied, and removing them can cause minor skin irritation, particularly if your skin is sensitive.

An ECG appointment should not delay emergency care. Seek urgent help for chest pressure or pain, severe breathlessness, fainting, sudden sweating with nausea, or a fast or irregular heartbeat accompanied by weakness or dizziness. If symptoms are brief but recurring, arrange prompt medical review and describe when they start, how long they last and what you are doing at the time.

Ask why an ECG is recommended, whether you need to rest before it, when the tracing will be reviewed and whether another test may be needed. If the result is described as abnormal, ask which finding was seen and what it means in relation to your symptoms.