The MUGA scan (Multiple Gated Acquisition scan) is a very valuable noninvasive tool for evaluating the size and pumping strength of the left ventricle. The left ventricle pumps blood out to the body.
For people who are in heart failure, the scan images will often show an enlarged and weakened left ventricle. The MUGA scan measures the ejection fraction, which is the proportion of blood that is pumped from the left ventricle with each heart beat. It is expressed as a percentage. The normal ejection fraction is between 50 and 75 percent.
This scan can also provide data about heart wall motion. Patients who have had a previous heart attack, the scan images often reveal inferior wall movement in the area of the heart muscle that was damaged and scarred by the heart attack.
The MUGA scan utilizes a special type of radiation detector called a Gamma Camera that generates a series of moving images of the blood as it passes through the heart during each heartbeat. The gamma camera identifies the injected tracer in the heart muscle and transfers the data to a computer. The computer will process these images into information that one of First Coast Heart & Vascular Center’s cardiologists can use to assess how efficiently the patient’s heart is pumping.
During the test, a small amount of a radioactive substance is injected into your blood and attaches to your red blood cells. The pictures are taken at the same intervals during each heartbeat. A computer examines the images. The images will show if areas of the heart muscle aren’t contracting normally and show how well the heart pumps blood.
This test can be performed while the patient is resting or exercising. A stress (exercise) test will provide the doctor a better idea of how well the patient’s heart handles work. It will help the doctor determine the kind and level of exercise right for the patient.
The cardiologist may order a MUGA Scan for the following reasons:
- In order to assess how much damage was done to the heart muscle after a heart attack.
- For patients with heart failure and/or cardiomyopathy in order to evaluate the size and pumping strength of the ventricles.
- If patient is having chemo for a cancer in order to monitor the ventricles’ pumping strength. Some cancer drugs can be harmful to the heart muscle.
Are there risks associated with a MUGA scan?
The radioactive substance that is injected is safe for most people. The patient’s body will eliminate it through the kidneys within about 24 hours. Pregnant or nursing patients should not have this test.
How to prepare for the test
- For a “resting” scan, avoid drinks containing alcohol or caffeine for several hours prior to the test.
- For an “exercise” scan, don’t drink or eat anything except water for 4 hours prior to your test. Wear comfortable shoes and loose-fitting clothes.
What happens during a MUGA scan?
During the scan, one of our Nuclear Medicine Technologists will place electrodes on the patient’s chest, arms and legs. The electrodes have wires that connect to an electrocardiograph machine to record the patient’s ECG. The ECG tracks the patient’s heartbeat during the test.
An intravenous line (IV) is inserted into a vein in the patient’s hand or arm so that the radioactive drug can be administered for imaging. For a “resting” scan, the patient will lie on a table with a special camera above it. The camera will take many pictures of the patient’s heart while the patient is resting.
For an “exercise” scan the patient will walk on a treadmill until they reach their peak activity level. Then the patient will stop and again lie on a table while the gamma camera takes pictures of their heart.
The test lasts about an 1 hour.
What happens after a MUGA scan?
- The patient can return to normal activities right away.
- The patient should drink plenty of water to remove the radioactive material from their body.