An electrocardiogram (EKG) is painless and harmless. A nurse or technician will attach 12 soft, sticky patches called electrodes to the skin of your chest, arms, and legs. The patches are about the size of a quarter.

This helps detect your heart’s electrical activity from many areas at the same time.

After the patches are placed on your skin, you’ll lie still on a table while the patches detect your heart’s electrical signals. A machine will record these signals on graph paper or display them on a screen.

The entire test will take about 10 minutes.