Cardiac Blood Pool Scan

Cardiac Blood Pool Scan

Test Overview

A cardiac blood pool scan shows how well
your heart is pumping blood to the rest of your body.
During this test, a small amount of a radioactive substance called a
tracer is injected into a vein. A gamma camera detects
the radioactive material as it flows through the heart and lungs.

The percentage of blood pumped out of the heart with each heartbeat is
called the
ejection fraction. It provides an estimate of how well
the heart is working.

This test has other names, including cardiac flow study, cardiac nuclear scan, first-pass scan, and MUGA scan. This test can be done in slightly different ways to check how well the heart is working.

Why It Is Done

A cardiac blood pool scan is done
to:

  • Check the size of the heart chambers (ventricles).
  • Check the pumping action of
    the lower ventricles.
  • Look for an abnormality in the wall of the
    ventricles, such as an
    aneurysm.
  • Look for abnormal movement of
    blood between the heart chambers.

How To Prepare

Before having a cardiac blood pool
scan, tell your health professional if you:

  • Are allergic to any medicines.
  • Are
    or might be pregnant.
  • Have recently had any test that uses a
    radioactive tracer, such as a bone scan or thyroid scan.
  • Have a
    pacemaker or other metal device implanted in your chest.
    These devices may make it hard to obtain clear pictures of the blood flow
    through the heart.

You may be asked not to eat or drink for a few hours before the
test. You may be asked to not have any caffeine or smoke for 4 to 6 hours before the
test.

If testing will include exercise, you should wear
comfortable shoes and clothing.

Many medicines may affect the
results of this test. Be sure to tell your health professional about all the
nonprescription and prescription medicines you take.

Talk to your
doctor about any concerns you have regarding the need for the test, its risks,
how it will be done, or what the results will mean. To help you understand
the importance of this test, fill out the
medical test information form ( What is a PDF document? ).

How It Is Done

A cardiac blood pool scan usually is
done in a hospital by a radiology or nuclear medicine technician. Most people do not have to stay overnight in the hospital.

How the test is done is based on the type of scan you are having and the way your hospital does this test.

There are different types of scans. Two of these types are:

  • First-pass scan. This scan makes pictures of the
    blood as it goes through the heart and lungs the first time.
  • MUGA scan (multigated acquisition scan). This scan uses the electrical signals of the heart to trigger the
    camera to take a series of pictures that can be viewed later like a video. The pictures record the heart's motion and check how well it is pumping blood. A MUGA scan may be done before and after your heart is stressed with exercise.

Before the test

You will need to remove any
jewelry that might interfere with the scan. You may need to take off all or
most of your clothes. You will be given a cloth or paper gown to use during the
test.

During the test

You will lie on an examination
table beneath the gamma camera.
Electrocardiogram (EKG, ECG) electrodes are attached
to your chest so that the electrical signal of your heart can also be detected.
Then the camera, which is a round metal instrument about
3 ft (1 m) wide, will be
positioned close to your body. If you are cold or uncomfortable lying on the
table, ask the technician for a pillow or blanket. The camera may be positioned
in different places across your chest to record different views of your
heart.

The technician cleans the site where the
radioactive tracer will be injected. The injection site is typically in the arm, but it may be in the neck. If the arm is used, an elastic band, or tourniquet, is then
wrapped around your upper arm to temporarily stop the flow of blood through the
veins in your arm. This makes it easier to put the needle into a vein properly.
A small amount of the radioactive tracer is then injected, usually into a vein
on the inside of your elbow. The radioactive tracer is designed to attach to your
blood cells for a short time.

If you are having a multigated
acquisition (MUGA) scan, a blood sample may be taken and the tracer added to
it, and then it will be reinjected into your vein.

The gamma
camera will take pictures as the radioactive tracer moves through your
bloodstream and into your heart. It is important not to move while the scan is
under way.

The camera does not produce any radiation, so you are
not exposed to any additional radiation while the scan is being done. You will
need to hold still during each view. You may be
asked to:

  • Change position for each different
    view.
  • Do some exercise between scans to see how well your
    heart functions after the stress of exercise.
  • Take nitroglycerin to
    see how well your heart responds to the medicine.

How long the test takes depends on the type of scan you are having. Ask your doctor how long your test will take. It could be about 1 hour, or it could take a few hours.

After the test

Once your scan is complete, you
usually will be able to leave the testing room right away. You may have to wait
at the test center until all of your scan images have been reviewed. If you
moved during the scan and the images turned out blurry, the scan may have to be
repeated.

Drink lots of water and urinate frequently after your
scan to make sure that the tracer flushes completely out of your body. It takes
a day or two for the tracer to be completely eliminated.

How It Feels

You may feel nothing at all from the
needle puncture when the tracer is injected, or you may feel a brief sting or
pinch as the needle goes through the skin. Otherwise, a cardiac blood pool scan
is usually painless. You will not feel anything from the operation of the gamma
camera. You may find it hard to remain still during the scan. The
examination table may feel cool. Ask for a pillow or blanket to make yourself
as comfortable as possible before the scan begins.

Risks

Allergic reactions to the radioactive
tracer are rare. Most of the tracer will be eliminated from your body (through
your urine or stool) within a day, so be sure to promptly flush the toilet and
thoroughly wash your hands with soap and water. The amount of radiation is so
small that it is not a risk for the people you come in contact with after the
test.

Occasionally, some soreness or swelling may develop at the
injection site. These symptoms can usually be relieved by applying moist, warm
compresses to your arm.

There is always a slight risk of damage to
cells or tissue from being exposed to any radiation, including the low level of
radiation released by the radioactive tracer used for this test.

Results

A cardiac blood pool scan shows how well
your heart is pumping blood to the rest of your body.

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 include the following:footnote 1

  • The ejection fraction is more than 55%.
  • The walls of the ventricles
    are contracting normally.

Many conditions can affect cardiac
blood pool scan results. Your doctor will discuss any significant
abnormal results with you in relation to your symptoms and past health.

What Affects the Test

Reasons you may not be able to
have the test or why the results may not be helpful include:

  • Fast or irregular heart
    rhythms.
  • Long-acting nitrate medicines and
    digoxin.
  • Recent nuclear scans, such as thyroid or bone
    scans.
  • Barium, such as from a
    barium enema, and bismuth, such as
    Pepto-Bismol.
  • Inability to remain still during the test. You may
    not be able to have the test if you have severe back problems or other physical
    disabilities that prevent you from lying flat.
  • Obesity.

What To Think About

  • Cardiac blood pool
    imaging is not usually done during pregnancy because the radiation could damage
    a developing
    fetus.
  • The cardiac blood pool scan is a safe and
    accurate way to determine overall heart function.
  • Multigated
    acquisition (MUGA) scans are routinely used before and after receiving a heart
    transplant to assess how well the heart is working. MUGA also may be used to
    monitor the ejection fraction in people receiving chemotherapy.
  • Generally, an
    echocardiogram provides as much information as a MUGA
    scan and is less invasive. But a MUGA scan can provide more accurate
    information about ejection fraction than an echocardiogram. To learn more, see the
    topic
    Echocardiogram.

References

Citations

  1. Chernecky CC, Berger BJ (2013). Laboratory Tests and Diagnostic Procedures, 6th ed. St. Louis: Saunders.

Other Works Consulted

  • Chernecky CC, Berger BJ (2013). Laboratory Tests and Diagnostic Procedures, 6th ed. St. Louis: Saunders.
  • Fischbach F, Dunning MB III (2015). A Manual of Laboratory and Diagnostic Tests, 9th ed. Philadelphia: Wolters Kluwer Health.
  • Pagana KD, Pagana TJ (2014). Mosby's Manual of Diagnostic and Laboratory Tests, 5th ed. St. Louis: Mosby.

Credits

ByHealthwise StaffPrimary Medical Reviewer Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology E. Gregory Thompson, MD - Internal Medicine Martin J. Gabica, MD - Family Medicine Adam Husney, MD - Family Medicine Specialist Medical Reviewer George Philippides, MD - Cardiology

Current as ofJanuary 11, 2018

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