Electrocardiogram

What does an electrocardiogram show?

An ECG (electrocardiogram) records the electrical activity of your heart at rest. It provides information about your heart rate and rhythm, and shows if there is enlargement of the heart due to high blood pressure (hypertension) or evidence of a previous heart attack (myocardial infarction).

What happens during an ECG?

What happens during an ECG test? Ten small sticky patches called electrodes are put on your arms, legs and chest. These are connected by wires to an ECG machine which picks up the electrical signals that make your heart beat. This electrical activity is recorded and printed onto paper.

An electrocardiogram records the electrical signals in your heart. It’s a common and painless test used to quickly detect heart problems and monitor your heart’s health.

Why it's done

An electrocardiogram is a painless, noninvasive way to help diagnose many common heart problems in people of all ages. Your doctor may use an electrocardiogram to determine or detect:

Abnormal heart rhythm (arrhythmias)
If blocked or narrowed arteries in your heart (coronary artery disease) are causing chest pain or a heart attack
Whether you have had a previous heart attack
How well certain heart disease treatments, such as a pacemaker, are working

You may need an ECG if you have any of the following signs and symptoms:

- Chest pain
- Dizziness, lightheadedness or confusion
- Heart palpitations
- Rapid pulse
- Shortness of breath
  Weakness, fatigue or a decline in ability to exercise

The American Heart Association doesn’t recommend using electrocardiograms to assess adults at low risk who don’t have symptoms. But if you have a family history of heart disease, your doctor may suggest an electrocardiogram as a screening test, even if you have no symptoms.