ECGECG is done so often and routinely that most people do not even consider it a special test. However, a lot can be learned from an ECG about the regularity (or irregularity) of the heartbeat. The fact that irregularities in the rhythm of the heartbeat can lead to stroke makes it an important tool in stroke evaluation.

What is an electrocardiogram?

An ECG is a painless test that is used to get information about the electrical activity of the heart, such as the rate and regularity of the heartbeat. The size and position of the heart chambers as well as any damage to the heart can also be obtained through an ECG. If you use an implanted device, like a pacemaker, its effect on the heart can also be studied through the results of this test.

Why do doctors use ECGs?

ECG is sometimes the only method of detecting irregularities in heart rhythm — such as atrial fibrillation — that can lead to the forming of blood clots that can later get flow to the brain. These blood clots can cause stroke by forming in the heart, coming loose and then getting lodged in a small artery of the brain.

ECG is performed on every stroke patient as part of the routine evaluation. However, the test shows only a “snapshot” of the electrical activity of the heart (about 5 minutes), and other devices may be used to find irregularities that occur less frequently.

What happens during an ECG?

You will be asked to lie down while the sites where the sticky electrodes will be attached are cleaned and shaven, if necessary. About 12 electrodes are attached to various parts of your body, six of which will be attached to the chest. The other six (called limb leads) will be attached accordingly: one on each arm, one on each leg, and two on the abdomen.

You must usually lie still during the test, while holding your breath for short periods at a time. The test requires ten to 15 minutes to complete.

What are the risks of ECG?

Since ECG is done without entering the body and does not use dyes or x-rays, there is no pain or risk associated with having an ECG.

How does an ECG work?

The electrodes contain wires that can detect the electrical signals of the heart through the skin. These wires are connected to a machine that traces the heart rhythm on graph paper. Because the results are immediately known, your doctor will instantly know the basic vital signs of your heart.