Key Points

• An electrocardiogram (EKG) is a simple, painless test that records the heart’s electrical activity.
• An EKG shows:
  • How fast your heart is beating
  • Whether the rhythm of your heart is steady or irregular
  • The strength and timing of electrical signals as they pass through each part of your heart
• EKGs are used to detect and evaluate many heart problems, such as heart attack, arrhythmia, and heart failure.
• Your doctor may recommend an EKG if you have signs or symptoms that suggest a heart problem. An EKG also may be done as part of a routine health exam, to check how medicine or a medical device is working, or for routine screening before major surgery. Your doctor may use EKG results to help plan your treatment for a heart condition.
• No special preparation is needed for an EKG. Before the test, let your doctor or doctor’s office know what medicines you’re taking. Some medicines can affect EKG results.
• For an EKG, soft, sticky patches called electrodes are attached to the skin of your chest, arms, and legs. You lie still on a table while the patches detect your heart’s electrical signals. A machine records these signals on graph paper or displays them on a screen. The entire test takes about 10 minutes.
• If you have a heart problem that isn’t present all of the time, you may need a special type of EKG, such as a stress test or Holter or event monitor.
• You usually can go back to your normal daily routine after an EKG.
• Many heart problems change the heart’s electrical activity in distinct ways. An EKG can help detect a number of heart problems. Results from an EKG can suggest problems such as lack of blood flow to the heart muscle, problems with heart rhythm or the heart’s pumping action, birth defects, problems with heart muscle or heart valves, and inflammation of the heart.
• An EKG has no serious risks. EKGs don’t give off electrical charges, such as shocks. You may have a mild rash where the electrodes were attached. This rash usually goes away without treatment.