A cardiac blood pool scan shows how well the heart is pumping blood out to the rest of your body. It can also evaluate how effectively the main pumping chamber of the heart (the left ventricle) is working by studying the motion of the heart walls. The percentage of blood pumped out of the left ventricle with each heartbeat is called the ejection fraction. By measuring the ejection fraction, the heart's pumping ability can be estimated.

During this test, a small amount of a radioactive substance called a tracer (radionuclide or radioisotope) is injected into a vein. A special camera detects the radioactive material as it flows through the heart and lungs. There are two types of cardiac blood pool scans.

• First-pass scan. This scan provides pictures of the blood as it makes its first pass through the heart and lungs. A first-pass scan can be used to diagnose congenital heart disease in children.
• Gated scan or multigated acquisition (MUGA) scan. MUGA scanning may be done after a first-pass 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 can be used to show the heart's motion and determine whether the ventricles are contracting properly. MUGA scanning may require 2 to 3 hours to obtain all the needed views and can be done before and after a person exercises. This test is usually not done on children.

Cardiac Blood Pool Scan
Results

Complete test results are usually available a day or two after the test is done. The most commonly reported value is the ejection fraction, which is the average amount of blood pumped out of the heart's left ventricle during each contraction.