A cardiac blood pool scan (also referred to as a MUGA scan) measures the heart’s ability to pump blood to the rest of your body. During this test, a small amount of the patients’ blood is removed and mixed with a radioactive substance called a tracer. Once the tracer binds or is tagged to the red blood cells the mixture is then injected back into the patient. A detector (also called a gamma camera) then detects the labeled cells as they flow through the heart.
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 - With this scan the tagged red blood cells are injected back into the patient rapidly through a large bore i.v. The gamma camera then takes pictures of the labeled blood as it first goes through the heart and lungs.
- Multigated acquisition (MUGA) scan - Using this scan the gamma camera acquires a series of pictures of the heart in synchrony with the patients ECG signals. The pictures record the heart's motion and determine if all of its segments are 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.
The scan is The scan is usually painless except for the pinching sensation during needle puncture. You will not feel anything from the operation of the gamma camera.
Abraham Salacata, MD, FACC