Health Library

What is a myocardial perfusion scan?

Myocardial perfusion is an imaging test. It’s also called a nuclear stress test. It
is done to show how well blood flows through the heart muscle. It also shows how well
the heart muscle is pumping. For example, after a heart attack, your doctor may order
this test to find areas of damaged heart muscle. This test may be done during rest
and while you exercise.

A myocardial perfusion scan uses a tiny amount of a radioactive substance, called
a radioactive tracer. The tracer travels through the bloodstream and healthy heart
muscle absorbs it. On the scan, the areas where tracer has been absorbed look different
from the areas that do not absorb it. Areas that are damaged or don’t have good blood
flow do not absorb the tracer.

Why might I need a resting myocardial perfusion scan?

Your doctor may order a resting myocardial perfusion scan in these cases:

• For chest pain, either new or occurring over a period of days or longer
• To diagnosis of coronary artery disease, which is the narrowing of the blood vessels
  that supply oxygen and nutrients to the heart muscle

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• After a heart attack (myocardial infarction, or MI) to look for heart muscle damage
• To assess blood flow to areas of the heart muscle that have had blood flow restored
  by bypass surgery, angioplasty, or stent placement
• To check for scar tissue in the heart from other disease not related to coronary artery
  disease

There may be other reasons for your healthcare provider to order a resting myocardial
perfusion scan.

What are the risks of a resting myocardial perfusion scan?

Except for the needle used to put in the IV, this test does not cause pain.

The injection of the radioactive tracer may cause some slight discomfort. Allergic
reactions to the tracer are rare.

You may want to ask your healthcare provider about the amount of radiation used during
the procedure and the risks related to your particular situation.

There may be other risks depending on your specific medical condition. Be sure your
healthcare provider knows about all of your medical conditions.

Make a list of questions you have about the procedure. Be sure to discuss these questions
and any concerns with your healthcare provider before the test. Bring a family member
or friend to the appointment to help you remember your questions and concerns.

Certain factors may interfere with or affect the results of this test. These include:

• Caffeine intake within 48 hours of the procedure
• Smoking or using any form of tobacco within 48 hours of the procedure
• Certain heart medicines

How do I get ready for a resting myocardial perfusion scan?

• Your healthcare provider will explain the procedure to you and you can ask questions.
• You will be asked to sign a consent form that gives your permission to do the test.
  Read the form carefully and ask questions if anything is not clear.
• Tell your healthcare provider if you are allergic to or sensitive to medicines, local
  anesthesia, contrast dyes, iodine, tape, or latex.
• You may need to fast (not eat or drink) before the procedure. Your healthcare provider
  will give you instructions as to how long to  withhold food or liquids. Do not eat
  or drink anything that contains caffeine for at least 48 hours before the procedure.
  Also, avoid any prescription and over-the-counter medicines that contain caffeine.
• Tell your healthcare provider of all medicines (prescription and over-the-counter),
  vitamins, herbs, and supplements that you take.
• If you are pregnant or think you may be, tell your healthcare provider. Radiation
  exposure during pregnancy may lead to birth defects.
• If you are breastfeeding, tell your healthcare provider. Radioactive tracer can contaminate
  breast milk.
• Tell your healthcare provider if you have a pacemaker or an implantable cardioverter
  defibrillator.
• Based on your medical condition, your healthcare provider may request other specific
  preparation.

What happens during a resting myocardial perfusion scan?

You may have a resting myocardial perfusion scan on an outpatient basis or as part
of your stay in a hospital. Procedures may vary depending on your condition and your
healthcare providers practice.

Generally, a resting myocardial perfusion scan follows this process:

1. You will be asked to remove any jewelry or other objects that may interfere with the
   procedure.
2. You will be asked to remove your clothing and will be given a gown to wear.
3. An intravenous (IV) line will be started in your hand or arm.
4. You will be connected to an ECG machine with leads that stick to your skin and a blood
   pressure cuff will be placed on your arm.
5. You will lie flat on a table in the procedure room.
6. The radioactive tracer will be injected into the IV in your hand or arm.
7. After the tracers has circulated through your body (10 to 60 minutes depending on
   the type of radioactive tracer being used), the scanner will take pictures of your
   heart. In this special kind of imaging test, called SPECT (single photon emission
   computed tomography), the scanner rotates around you as it takes pictures. The table
   slides into the hole of the scanner, which is a large, donut-shaped machine.
8. You will be lying flat on a table while the images of your heart are made. Your arms
   will be on a pillow above your head. You will need to lie very still while the images
   are being taken, as movement can affect the quality of the images.
9. If you have any symptoms, such as dizziness, chest pain, extreme shortness of breath,
   or severe fatigue, at any point during the procedure, let the healthcare provider
   know.
10. After the scan is done, the IV line will be removed, and you will be allowed to leave,
    unless your healthcare provider tells you differently.

What happens after a resting myocardial perfusion scan?

Move slowly when getting up from the scanner table to avoid any dizziness or lightheadedness
from lying flat for the length of the procedure.

Drink plenty of fluids and empty your bladder often for 24 to 48 hours after the test.
This helps flush the remaining radioactive tracer from your body.

The IV site will be checked for any signs of redness or swelling. If you notice any
pain, redness, or swelling at the IV site after you return home, tell your healthcare
provider. This may be a sign of infection or other type of reaction.

Your healthcare provider may give your other instructions after the procedure, depending
on your particular situation. If the perfusion scan shows you may have a serious or
life threatening cardiac disease, your healthcare provider may talk to you about a
same-day cardiovascular procedure.

Next steps

Before you agree to the test or the procedure make sure you know:

• The name of the test or procedure
• The reason you are having the test or procedure
• What results to expect and what they mean
• The risks and benefits of the test or procedure
• What the possible side effects or complications are
• When and where you are to have the test or procedure
• Who will do the test or procedure and what that person’s qualifications are
• What would  happen if you did not have the test or procedure
• Any alternative tests or procedures to think about
• When and how will you get the results
• Who to call after the test or procedure if you have questions or problems
• How much will you have to pay for the test or procedure