A cardiac blood pool scan shows how well your heart is pumping blood to the rest of your body. During this test, a small amount of a radioactive substance called a tracer is injected into a vein. A gamma camera detects the radioactive material as it flows through the heart and lungs.

The percentage of blood pumped out of the heart with each heartbeat is called the ejection fraction. It provides an estimate of how well the heart is working.

There are two types of cardiac blood pool scans.

• First-pass scan. This scan makes pictures of the blood as it goes through the heart and lungs the first time. A first-pass scan can be used in children to look for heart problems that have been present since birth (congenital heart disease).
• Gated scan or multigated acquisition (MUGA) scan. This scan uses the electrical signals of the heart to trigger the camera to take a series of pictures that can be viewed later like a motion picture. The pictures record the heart's motion and determine if it is pumping (contracting) properly. MUGA scanning may take 2 to 3 hours to obtain all the needed views and can be done both before and after you exercise. You may be given nitroglycerin to see how your heart responds to this medicine. MUGA scanning may be done after a first-pass scan. It is usually not done on children.

Why It Is Done

A cardiac blood pool scan is done to:

• Check the size of the heart chambers (ventricles).
• Check the pumping action of the lower ventricles.
• Look for an abnormality in the wall of the ventricles, such as an aneurysm.
• Look for abnormal movement of blood between the heart chambers.

How To Prepare

Before having a cardiac blood pool scan, tell your health professional if you:

• Are allergic to any medicines.
• Are or might be pregnant.
• Have recently had any test that uses a radioactive tracer, such as a bone scan or thyroid scan.
• Have a pacemaker or other metal devices, such as spinal fixation rods, in your chest. These devices may make it difficult to obtain clear pictures of the blood flow through the heart.

You may be asked not to eat or drink for 4 hours before the test. You should not have any caffeine or smoke for 4 to 6 hours before the test.

If testing will include exercise, you should wear comfortable shoes and clothing.

Many medicines may affect the results of this test. Be sure to tell your health professional about all the nonprescription and prescription medicines you take.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will indicate. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).