Electrocardiography

Electrocardiography is a test that measures your heart’s electrical activity. It's quick, painless, and harmless.

The results of that test are shown in an electrocardiogram. It looks like a wavy line with spikes on a grid (a tracing). The electrocardiogram gives doctors information about:

• The part of your heart that triggers each heartbeat

• Your heart's electrical pathways

• Your heart's rate and rhythm

ECG: Normal Heartbeat

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From D Dubin, Rapid Interpretation of EKGs, 1996, Cover Inc., p. 95; with permission.

You may have an ECG:

The Conduction System

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• As part of a routine checkup, if you're middle-aged or older

• As a way for the doctor to evaluate symptoms that could be from a heart problem, such as chest pain, trouble breathing, a fast or abnormal heartbeat, or swelling in your legs

• Small, round sensors (electrodes) that stick to the skin are placed on your arms, legs, and chest

• Wires that snap on to the sensors are connected to a machine

• As your heart beats, the sensors measure your heart’s electrical currents

• The machine records information from each sensor and develops an ECG (a wavy line with spikes) for your doctor to read

There are no side effects. An ECG won't hurt at all during or after the test.

Electrocardiogram

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An ECG helps your doctor learn many things about your heart, including:

• If you’ve had or are having a heart attack

• If you have an abnormal heart rhythm

• If your heart isn't getting enough blood and oxygen

• If the muscular wall of your heart is too thick

• If there are bulges in weak areas of your heart’s walls (the bulge is called an aneurysm)

If you've had heart problems, you might want to keep a copy of your ECG with you (ask your doctor if you should). That way, if you have an emergency, the doctor treating you can compare your older ECG with a new ECG.