Cardiac – MUGA Study

What is a MUGA scan?

A MUGA (Multigated Acquisition) scan can be useful for a wide range of studies, but its primary task is to determine the left-ventricular ejection fraction of the heart. This is a measure of the heart’s efficiency at pumping blood around the body.

Is there any special preparation for the scan?

There is no preparation for this scan. You can eat as normal and take any medication.

What happens when I arrive in the department?

Upon arrival to the department, you should let reception know that you are here. Shortly after you will be given a small injection into a vein in your arm. This will be done by a radiographer in one of the treatment rooms. This injection helps the radioactivity to ‘stick’ to your blood cells. This substance will not damage the cells and you will not feel anything.

How long between the initial injection and the scan?

After this initial injection there will be a brief wait of about ten to fifteen minutes.

How are the images acquired?

For the scan we may need you to undress to the waist to be able to attach electrodes from an ECG machine to you. While lying slightly under the gamma camera, a small amount of a radioactive substance will be injected into a vein in your other arm. This injection is also not hazardous.

We will then take a series of pictures over a period of about 15 to 45 minutes. You will need to lie very still on the couch for the pictures. The radiographer will remain in the room at all times.

Cardiac Stress/Rest test

What is a stress/rest cardiac scan?

A stress/rest cardiac scan is used to assess the blood supply to the heart muscle. The test is performed on 2 different days with the rest part of the test first.

What happens in the rest part of the test?

A GTN (Glyceryl trinitrate) spray is used before the radioactive injection. The spray is administered under the tongue and helps to improve the quality of images. One hour later images are taken of your heart. If you are prescribed GTN spray please bring it with you for the test, otherwise we will provide one for you.

What happens in the stress part of the test?

ECG leads are placed on your chest and a small needle (cannula) is inserted into your arm. If you are able, you are asked to perform light exercise on a bicycle. While you are undertaking this, a pharmacological stressing agent, called Adenosine is administered through the cannula in your arm. This increases your heart rate. Half way through the administration a small injection of radioactivity is given (also through the cannula). Once the administration is finished, the needle will be removed from your arm. One to three hours later images are taken of your heart on a gamma camera.

How are the images taken?

For the images you will need to lie still for approximately one hour. You are not required to remove any clothes but you will be asked to remove jewellery and other metallic objects before the scan as these will interfere with the image. There is no tunnel to go through although the camera will come close to your body. A radiographer will remain in the room during the scan.

Do I need to prepare for the scan?

It is very important that you follow the instructions below otherwise we cannot perform the test.

Rest test

• You can have a light breakfast on the day of the test (eg toast and fruit juice) but then nothing until after the injection of radioactivity.

• You do not need to stop taking any drugs for this part of the test.

Stress test

• Do not have anything containing caffeine eg tea, coffee or Coca cola for 24 hours before the test.

• If you are taking Beta Blockers, Aminophylline, Theophylline or Dipyridamole you must not take them for 24 hours before the test.

• If you are on Xanthines you must not take them 12 hours before the test.

• You can have a light breakfast on the day of the test (eg toast and fruit juice) but then nothing until after the injection of radioactivity.

What should I wear for the scan?

Wear comfortable clothing and shoes suitable for light exercise so that we are able to place the ECG leads easily.

What can I do between the injection and the scan?

In the time between the injection and scan, you are free to leave the department. You can eat and drink and take any medications that you require. You will be notified of the time that you should return to the department.

Are there any side effects?

The adenosine can cause some side effects (feeling hot, shortness of breath, dizziness, chest tightness), similar to strenuous exercise, while it is being administered. To ensure your safety this procedure is closely supervised and we will monitor your heart rate and blood pressure. We can stop the injection at any point, should any problems arise, but it is important that we complete the infusion, if possible, to ensure we get the best images.

GTN can make you feel a little giddy so we may ask you to lie down for 15-20 mins after using the spray.

There are no side effects from the radioactive injection.

Are there any risks from the radioactive injection?

The amount of radioactivity you will receive is small, similar to doses received frm X-Ray examinations.

There is no risk to other members of your family but if there are small children or babies in the house it is advisable not to spend long periods of time cuddling them for 24 hours after each injection.

Is there anything I should tell the staff?

Please tell the Nuclear Medicine staff if you are breast feeding or if there is any chance you could be pregnant before you receive the injection.

The staff also need to know if you are asthmatic.

Can I bring a friend/relative with me?

You are welcome to bring a companion with you but please do not bring children or pregnant women with you unless it is absolutely necessary.

When will the doctor have the results?

The doctor who referred you for the scan will usually have a report within one week.

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