An electrocardiogram records the electric currents produced by the heart. It is known as either an EKG or ECG. It measures the current on the skin by electrodes attached to the chest. These are harmless devices with wires leading to a recording machine.

An ECG helps identify various problems with the heart. It is used for the following:
* assess the damage from a heart attack,
* identify heartbeat abnormalities,
* identify diseases of the heart muscle,
* diagnose imbalance with the body's salts and minerals,
* to monitor drug therapy for the heart, and
* see if a pacemaker is working.

A resting ECG takes about 5 to 10 minutes. An EKG that involves exercise may last somewhat longer. The examiner attaches electrodes to the chest, wrists, and legs with a special gel. A recording machine will trace a wave pattern for each wire lead. For a resting ECG, the person must remain still and quiet. If an electrode detaches, the doctor or technician presses it back into place.

An exercise ECG is performed while the person walks on a treadmill or cycles. This gives important information beyond the resting ECG. The examiner asks the person to maintain or increase effort. Blood pressure is measured along with heart activity. Unless the person has pain or fatigue, the test goes until he reaches a target heart rate. Monitoring usually continues for 10 or 15 minutes after the exercise stops. People with severe heart problems usually do not have exercise ECGs.

The person's healthcare provider receives the tracings from an ECG for interpretation.

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