What is a myocardial perfusion scan?

Myocardial perfusion scan is an imaging test. It's also called a nuclear stress test. It's 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 healthcare provider 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. This is 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 don't absorb it. Areas that are damaged or don't have good blood flow don't absorb the tracer.

Why might I need a resting myocardial perfusion scan?

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

• For chest pain, either new or occurring over a few days or longer

• To diagnose coronary artery disease (CAD). This is the narrowing of the blood vessels that supply oxygen and nutrients to the heart muscle.

• After a heart attack (myocardial infarction) to look for heart muscle damage. Or if the heart isn't working correctly.

• 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 CAD

There may be other reasons for your 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 (intravenous) line, this test doesn't 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 provider knows about all of your medical conditions. Make a list of questions you have about the procedure. Be sure to talk about these questions and any concerns with your 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:

• Having caffeine 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'll be asked to sign a consent form that gives your permission to do the test. Read the form carefully and ask questions if anything isn't clear.

• Tell your provider if you're 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 provider will give you instructions as to how long to withhold food or liquids. Don't eat or drink anything that contains caffeine for at least 48 hours before the procedure..

• Tell your provider about all prescription and over-the-counter medicines, vitamins, herbs, and supplements that you take.

• If you're pregnant or think you may be, tell your provider. Radiation exposure during pregnancy may lead to birth defects.

• If you're breastfeeding, tell your provider. Radioactive tracer can contaminate breast milk.

• Tell your provider if you have a pacemaker or an implantable cardioverter defibrillator.

• Based on your medical condition, your provider may ask for 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 provider's practice.

Generally, a resting myocardial perfusion scan follows this process:

1. You'll be asked to remove any jewelry or other objects that may interfere with the procedure.

2. You'll be asked to remove your clothing and will be given a gown to wear.

3. An IV line will be started in your hand or arm.

4. You will be connected to an electrocardiogram machine with leads attached to stickers on your skin. And a blood pressure cuff will be placed on your arm. These will monitor you during the test.

5. You'll lie flat on a table in the procedure room.

6. The radioactive tracer will be injected into the IV line in your hand or arm.

7. After the tracer 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. During this SPECT (single photon emission computed tomography) imaging test, the scanner rotates around you as it takes pictures. The table slides into the hole of the scanner, which is a large, doughnut-shaped machine. Some facilities may use a PET (Positron emission tomography) camera to get images.

8. You'll 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'll 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 provider know.

10. After the scan is done, the IV line will be removed, and you'll be allowed to leave, unless your provider tells you differently.

What happens after a resting myocardial perfusion scan?

Move slowly when getting up from the scanner table to prevent 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 provider may give you other instructions after the procedure, depending on your situation. If the perfusion scan shows you may have a serious or life-threatening cardiac disease, your provider may talk with you about an urgent or a same-day cardiovascular procedure.

Next steps

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

• The name of the test or procedure

• The reason you're 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're to have the test or procedure

• Who will do the test or procedure and what that person’s qualifications are

• Any alternative tests or procedures to think about

• When and how you'll get the results

• Who to call after the test or procedure if you have questions or problems

• How much you'll have to pay for the test or procedure