Multiple Gated Acquisition Study
Multiple Gated Acquisition Study (MUGA)
What is it?
A multiple gated blood pool scan produces a moving image of the beating heart, and from this image determinations can be made regarding the health of the cardiac ventricles (the heart’s major pumping chambers). The scan uses a nuclear (radioisotope) dye that shows how blood pools in the heart during rest, exercise, or both.
How does it work?
MUGA makes use of a radioactive substance that is injected into the bloodstream. The radioactive substance "tags" or "labels" the red blood cells in the blood. This substance is safe and will not harm blood or organs. Doctors will then use a gamma-ray camera to take pictures of the heart as the "tagged" red blood cells circulate.
Reasons for an Exercise Stress Test
If a patient has had a heart attack, or any other disease that affects the heart muscle, the MUGA scan can localize the portion of the heart muscle that has sustained damage, and can assess the degree of damage. The test can also tell doctors how well the heart is pumping blood and if it is working harder to make up for one or more blocked arteries.
Most importantly, this scan is very useful for measuring overall cardiac function by determining the "ejection fraction," which is the percentage of blood that is pumped out of the heart's lower chambers (called the ventricles) with each heartbeat.
This test can be done while resting or exercising.
What to expect
In a resting study, a technician will clean areas on the chest where small metal disks (electrodes) will be placed. The electrodes have wires (leads), which are attached to a nuclear imaging computer. Then the technician will give two injections: the first injection prepares the red blood cells, and the second is used to "label" the red blood cells. The patient will then lie down on an examination table, which has a special camera (gamma-ray) around it which takes a number of pictures of the heart.
If a doctor ordered an exercise gated blood pool test, the patient will be moved to a different examination table. When lying down, there will be pedals at the end of the bed for which, while still lying down, the patient begins to pedal as if riding a bicycle. Using the gamma-ray camera, the technician will take a number of pictures of the heart.
The radioactive substance is not harmful to the body or organs. After the test is over the patient may resume normal activities.