You know that feeling when something just isn’t quite right? Maybe you’ve noticed you’re getting breathless more easily, or there’s an unusual tiredness that won’t go away. Sometimes, it’s a little nudge from your body telling us we need to take a closer look, especially at your heart. Or, perhaps you’re on a journey with a different treatment, like for cancer, and we want to keep a close eye on how your heart is handling things. That’s where a test called a MUGA scan can be really helpful.
What Exactly is a MUGA Scan?
So, what is this MUGA scan? Think of it as a special kind of moving picture show for your heart. The full name is a multigated acquisition scan, but we usually just say MUGA. It’s an imaging test that helps us see how well your heart is pumping blood.
To do this, we use a tiny, safe amount of a radioactive substance, called a radionuclide (or sometimes a radiotracer), and a special camera. This substance hitches a ride with your blood, and as it flows through your heart, the camera takes pictures. It’s pretty clever, really. This lets us see your heart muscle as it contracts (squeezes) and relaxes. We can do this while you’re resting, and sometimes while you’re doing a bit of light exercise.
Other names you might hear for it are radionuclide ventriculography (RNVG) or equilibrium radionuclide angiocardiography (ERNA). Sounds complicated, I know, but the idea is simple: check the pump!
What Does a MUGA Scan Show Us?
The main thing we’re looking at with a MUGA scan is something called your ejection fraction, or EF. Now, your EF is simply a measurement of how much blood your heart pumps out with each beat.
We measure EF as a percentage. For instance, if your EF is 65%, it means that when your heart fills up and then squeezes, it pumps out 65% of the blood that was in that chamber. Generally, a healthy heart has an EF somewhere between 50% and 75%.
Why Might You Need a MUGA Scan?
There are a few common reasons why I, or another doctor, might suggest a MUGA scan.
Often, it’s if you’re showing signs that could point to heart failure. This is a condition where your heart isn’t pumping blood as efficiently as it should. Some of the things that might make us think about this include:
- Chest pain (what we call angina)
- Feeling dizzy
- Persistent fatigue
- Shortness of breath (medically, dyspnea)
- Swelling in your hands or feet (edema)
Another important time we use MUGA scans is before, during, or after certain cancer treatments. Some treatments, while life-saving, can be tough on the heart. These can include:
- Bone marrow transplant
- Chemotherapy
- Immunotherapy
- Radiation therapy to the chest area
The scan helps us monitor your heart and make sure it’s staying strong.
MUGA Scan vs. an Echo Test: What’s the Difference?
You might have heard of an echocardiogram, or “echo.” Both MUGA scans and echos give us images of your heart beating. An echo uses sound waves – a bit like an ultrasound – with a device the doctor or technician moves over your chest.
A MUGA scan, being a nuclear imaging test with that radiotracer, can sometimes give us a slightly more precise reading of the ejection fraction. Both are good tests; we just choose the one that’s best for your specific situation.
Getting Ready for Your MUGA Scan
So, what’s involved if you’re scheduled for one?
How Does It Work?
The MUGA heart scan uses that tiny bit of a radioactive chemical, usually something called technetium-99m-pertechnetate (Tc-99m). Don’t let the long name worry you; it’s a standard tracer.
A small amount of this Tc-99m is injected into a vein. It then attaches itself to your red blood cells – those are the cells that carry oxygen around your body. As your heart beats and pumps these tagged blood cells, that special camera (often called a gamma camera) takes pictures, showing us exactly how the blood is moving.
How to Prepare
We’ll give you specific instructions, of course, but generally:
- You’ll likely be asked to avoid eating or drinking for a few hours, maybe up to six, before the test.
- Caffeine is usually a no-go for a bit beforehand too, as it can speed up your heart rate and potentially affect the results.
- It’s really important to tell us about all medications you’re taking. Sometimes, we might ask you to temporarily stop certain heart medicines, like nitrates (you might know them as Nitrostat® or NitroMist®) or digoxin (like Digitek® or Lanoxin®), before your scan. But please, don’t stop any medication unless we specifically tell you to!
What to Expect During the Scan
The whole thing can take anywhere from one to three hours. It’s not painful, though. Here’s a typical rundown:
- You’ll lie down comfortably on an exam table. The special camera will be positioned above your chest.
- A technician will attach a few small sticky pads, called electrodes, to your chest. These are connected to an ECG machine to monitor your heart’s electrical activity during the scan – it helps time the pictures perfectly with your heartbeat.
- Then, you’ll get that injection of the radiotracer into a vein, usually in your arm. You might feel a little pinch, like any injection.
- The camera will then start taking pictures from several different angles. You’ll need to lie as still as possible during these.
Sometimes, especially if we want to see how your heart performs under a bit of demand, the technician might ask you to do some light exercise between sets of pictures. This could be walking on a treadmill or pedaling a stationary bike. This helps your cardiologist (that’s the heart specialist) see how your heart responds to stress.
And After the MUGA Scan?
Once it’s all done, you can usually get right back to your normal day. You can drive, eat, and do whatever you usually do.
It’s a good idea to drink plenty of fluids – water is great – for the day or two after the test. This just helps your body flush the radiotracer out of your system a little quicker.
Are There Any Risks?
For most people, MUGA scans are very safe. The amount of radiation from the radiotracer is small – often less than a standard X-ray – and it’s not harmful. It usually clears out of your body within about 24 hours.
However, it’s crucial to tell us if you are pregnant, think you might be pregnant, or if you are breastfeeding. We generally don’t recommend these types of tests for pregnant or nursing mothers because of the potential, however small, for the radiotracer to affect the baby. We’d always look for alternatives in these cases.
Understanding Your Results
After the scan, a specialist will look at the images and calculate that ejection fraction (EF) we talked about.
- Remember, a typical EF is between 50% and 75%.
- An EF below 50% might suggest your heart isn’t pumping as strongly as it should.
- An EF above 75% can sometimes, though less commonly, also point to certain heart conditions.
Your doctor will sit down with you to discuss what your specific results mean. It’s not just about the number; it’s about what that number means for you, in the context of your health and any symptoms you’ve been having. We’ll then talk about any next steps, which might include further tests or discussing treatment options if needed.
Take-Home Message: Key Things About Your MUGA Scan
Let’s quickly recap the important bits about a MUGA scan:
- It’s an imaging test to see how well your heart is pumping blood.
- It measures your ejection fraction (EF) – the percentage of blood pumped with each beat.
- It’s often used if there are signs of heart failure or to monitor heart health during/after cancer treatments.
- It involves a safe, small injection of a radiotracer and pictures taken with a special camera.
- Preparation usually involves some fasting and avoiding caffeine.
- The test itself is generally safe, with the radiotracer leaving your body within a day.
- Always tell your doctor if you’re pregnant or breastfeeding.
You’re not alone in this. If we’re suggesting a MUGA scan, it’s because we want the best information to help you. We’ll walk through it all together.
