What is a MUGA Scan?
A multiple gated acquisition (MUGA) scan is a test that uses a radioactive substance, called a tracer, to access how well your heart is pumping blood.
How Does it Work?
During a MUGA scan, a small amount of radioactive tracer is injected into a vein in your arm. The tracer "tags" or "labels" your red blood cells by attaching to them for a few hours.
The tagged red blood cells distributes evenly in your blood. As these cells travel through the heart, the tracer gives off a small amount of radiation that can be detected with a scanning camera. A computer processes the information and produces images that show how radioactivity is distributed in the heart.
The camera is linked to an electrocardiogram (ECG). Your heart's electrical signals trigger the camera to take a series of pictures at precise moments during the heartbeat cycle. This is called "gating."
Gating creates images that are sharp and clear. It also produces moving images that show the left and right lower chambers, or ventricles, as they contract and pump blood.
A MUGA scan is usually done while you are at rest. In some cases, it may be done while you exercise.
What Does it Show?
The MUGA scan is especially useful for assessing the size and pumping strength of the ventricles. In people with heart failure, for example, the scan images often show enlarged and weakened ventricles.
The ejection fraction is a commonly used measure of your heart's pumping strength. The ejection fraction is the proportion of blood that is pumped from the left ventricle (the main pumping chamber) with each heartbeat. A normal ejection fraction is greater than 50 percent. Patients with heart failure often have an ejection fraction of less than 40 percent.
The MUGA scan also provides information about hear wall motion. In people who have had a heart attack, for example, the scan images often show poor wall movement in the area of the heart muscle that was damaged and scarred.
Preparation for a MUGA Scan...
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If you are scheduled for a rest MUGA scan, no special preparation is necessary.
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If you are scheduled for an exercise MUGA scan, you'll be instructed not to eat, drink or smoke for at least 3 hours before the test.
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If you take heart medications, check with your doctor. You may be asked to stop certain medications a day or two before the test.
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Wear comfortable clothing and shoes that are suitable for exercise.
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The procedure will be explained to you and you will be asked to sign a consent form.
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How Long Does it Take?
A rest MUGA scan usually takes less than an hour. It the test also includes an exercise scan, it may take up to 3 hours.
After the test, you can resume your normal activities, including driving.