An electrocardiogram (ECG or EKG) is a diagnostic test that records the electrical signals in the heart. It is a simple, painless, and quick test that is used to help diagnose and monitor many types of heart conditions and their treatment. During the test, electrodes are placed on the chest, arms, and legs to record the hearts electrical signals, which cause the heart to beat. The signals are shown as waves on an attached computer monitor or printer.

ECG results can give a healthcare provider details about the following:

• Heart rate: An ECG can help identify an unusually fast heart rate (tachycardia) or an unusually slow heart rate (bradycardia).
• Heart rhythm: An ECG can help detect an irregular heartbeat or arrhythmia.
• Size or thickness of certain chambers of the heart: An ECG can help identify if certain chambers of the heart are enlarged or thickened.
• Blood flow to the heart muscle: An ECG can help detect if there is poor blood flow to the heart muscle, which is called ischemia.
• Diagnosis of a heart attack: An ECG can help diagnose a heart attack.

ECG tests are mainly used for people who have symptoms of a heart condition or have already been diagnosed with a heart condition. They are not generally used to screen people who dont have symptoms unless they have an increased risk of developing heart disease. An ECG is a "snapshot" of the hearts activity over a very short time. If a person has heart symptoms that come and go, a regular ECG may not catch the problem. In that case, a healthcare provider may recommend that the person wear a small portable EKG.