Heart blood pool scan & bull; hello healthy

Definition

What is a heart blood pool scan?

A heart blood pool scan shows how well your heart pumps blood around the body. During this test, a small amount of a radioactive substance called a tracer is injected into a vein. A gamma camera will detect radioactive substances flowing through the heart and lungs. The percentage of blood pumped out of the heart with each beat of the heart is called the ejection fraction. This provides an idea of how well the heart is working.

There are two types of cardiac blood pool scans:

First-pass scan. This scan produces an image of the blood as it first passes through the heart and lungs. First-pass scans can be used in children to look for problems in the heart that are present at birth (congenital heart disease).

Gated scan or multigated acquisition (MUGA) scan. This scan uses an electrical signal to trigger the camera to take several pictures that can later be viewed as moving images. The image records the movement of the heart and determines whether the heart is pumping properly. A MUGA scan can take 2 to 3 hours to gather everything there is to see and can be done either before or after you exercise. You may be given nitroglycerin to see how your heart responds to this drug. MUGA scans can be performed after the first-pass scan. This scan is not usually performed on children.

When should I have a heart blood pool scan?

A heart blood pool scan is done to:

check the size of the heart chambers (ventricles)
check the pumping action of the heart in the lower ventricles
look for abnormalities in the walls of the ventricles such as an aneurysm
look for abnormalities in the movement of blood between the chambers of the heart.

Precautions & warnings

What should I know before having a heart blood pool scan?

Cardiac blood pool imaging is usually not performed during pregnancy because the radiation rays can damage the developing fetus. MUGA scans are routinely used before and after receiving a heart transplant to assess how well the heart is working. MUGA is also used to monitor ejection fraction in those receiving chemotherapy. In general, an echocardiogram provides as much information as a MUGA scan and is less invasive. However, MUGA scans provide more accurate information regarding ejection fraction than echocardiograms, especially for people with obesity or pulmonary disease.

Process

What should I do before having a heart blood pool scan?

Before performing a heart blood pool scan, tell your medical personnel if you:

allergic to a drug
is or may be pregnant
recently performed tests with a radioactive tracer, such as a bone or thyroid scan
have a pacemaker or other metal device that fits inside your chest. These devices can make it difficult to obtain a clear image of blood flow through the heart

You may be asked not to eat or drink for several hours before the test. You should not consume caffeine or smoke for 4 to 6 hours before the test. If the exam includes exercise, you should wear comfortable clothes and shoes. Many drugs can affect the results of this test. Be sure to tell your doctor about all prescription and nonprescription medicines you use.

You will be asked to remove any jewelery that could interfere with the scan process. You may need to remove all or part of your clothes. You will be given special clothes during the examination.

How is the heart blood pool scan?

You will lie on an examination table under the surveillance of a gamma camera. Electrocardiogram (EKG, ECG) electrodes will be attached to your chest so that the electrical signals of your heart can be detected as well. Then the camera, which is a round metal instrument about 3 ft (1 m) wide, will be positioned close to your body. If you feel cold or uncomfortable lying on a table, ask the technician for a pillow or blanket. The camera will be positioned at different places on your chest to record different images of your heart.

The technician will clean the area on your arm where the radioactive tracer will be injected. An elastic band, or tourniquet, is then wrapped around your upper arm to temporarily stop the flow of blood in your arm. This makes it easier to properly inject the needle into the vein. A small amount of radioactive tracer is then injected, usually into a vein just inside your elbow.

If you have a MUGA scan, a blood sample will be drawn and a tracer will be added to the sample, then will be injected back into your vein.

A gamma camera will take pictures as the radioactive tracer travels through your bloodstream and into your heart. It is important not to move while the scan is in progress.

The camera does not produce any radiation, so you are not exposed to radiation when the scan is complete. You will need to remain still during each shot, which can take up to 5 minutes. You may be asked to:

changing the position for each image is different
do some light exercise in between scans to see how well your heart is functioning after stressful exercise
use nitroglycerin to see how the heart responds to this drug

The radioactive tracer is designed to attach to your blood cells, which takes 20 to 30 minutes. You will then wait 2 to 4 hours for the tracer to be completely absorbed by your red blood cells. During this time, you will likely remain at the test center. Some test centers allow you to leave and come back when your test time arrives. The test usually takes 10 minutes to 1 hour, depending on the research being carried out. MUGA scans take 2 to 3 hours to collect all the required images.

What should I do after having a heart blood pool scan?

When your scan is done, you can usually go straight to the test room. You may wait at the test center until all of your scanned images have been reviewed. If you move during the scan process and the resulting image is not clear, the scan may need to be repeated.

Drink lots of mineral water and urinate frequently after the scan is over to make sure the tracer is completely out of the body. It can take one to two days for the tracer to completely disappear.

If you have questions related to this test process, please consult your doctor for a better understanding.

Explanation of the Test Results

What do my test results mean?

The most commonly reported value is the ejection fraction, which is the average amount of blood pumped out of the heart's left ventricle during each contraction. Normal results are:

ejection fraction is 55% to 60%
the walls of the ventricles contract normally

Many conditions can affect the results of a heart blood pool scan. The doctor will discuss with you any abnormal results related to your symptoms and medical history.