An electrocardiogram (ECG or EKG) is a noninvasive and painless test that records the electrical signals in the heart. The pattern of these signals can help tell your physician whether your heart is normal, under stress or having rhythm problems. An ECG can also detect changes in the heartbeat, strain on the heart or other damage.

During an ECG, electrodes (small, plastic patches that stick to the skin) are placed at certain spots on the chest, arms and legs. The electrodes are connected to an ECG machine by lead wires. The electrical activity of the heart is recorded by the lead wires, printed on graph paper, and analyzed and interpreted by cardiovascular physicians.