Resting Myocardial Perfusion Scan
What is a myocardial perfusion scan?
A myocardial perfusion scan is a type of nuclear medicine imaging test. This means that a tiny amount of a radioactive substance, called a radioactive tracer (also called a radiopharmaceutical or a radionuclide), is used during the scan to help show the tissue under study, in this case, the heart.
A resting myocardial perfusion scan is used to assess blood flow to the heart muscle and determine what areas of the heart tissue have decreased blood flow. The is done by injecting a radioactive tracer (usually thallium or technetium) into a vein in the arm or hand. The tracer travels through the bloodstream and is absorbed by the healthy heart muscle. On the scan, the areas where tracer has been absorbed look different from the areas that do not absorb it. The tracer may not be absorbed due to damage to the tissue from decreased or blocked blood flow.
Why might I need a resting myocardial perfusion scan?
Possible reasons a resting myocardial perfusion scan may be done include:
- Chest pain, either new onset or occurring over a period of days or longer
- A diagnosis of coronary artery disease, which is the narrowing of the blood vessels that supply oxygen and nutrients to the heart muscle.
- 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 been reperfused (blood flow has been restored) by bypass surgery, angioplasty (the opening of a coronary artery using a balloon or other method), or stent placement (a tiny expandable metal coil is placed inside the artery to keep the artery open)
There may be other reasons for your healthcare provider to recommend 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 to discuss any concerns with your healthcare provider prior to the procedure.
Certain factors may interfere with or affect the results of this test. These include, but are not limited to, the following:
- Caffeine intake within 48 hours of the procedure
- Smoking or using any form of tobacco within 48 hours of the procedure
- Certain heart medications
How do I get ready for a resting myocardial perfusion scan?
- Your healthcare provider will explain the procedure to you and ask if you have any 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 medications, local anesthesia, contrast dyes, iodine, tape, or latex.
- Fasting (not eating or drinking) may be required before the procedure. Your healthcare provider will give you instructions as to how long you should withhold food and/or liquids. You should not eat or drink anything that contains caffeine for at least 48 hours prior to the procedure. Some prescription and over-the-counter medications contain caffeine and should be avoided. Some over-the-counter medications that contain caffeine include Anacin, Excedrin, and NoDoz.
- Tell your healthcare provider of all medications (prescription and over-the-counter), vitamins, herbs, and supplements that you are taking.
- If you are pregnant or think you may be pregnant, you should tell your healthcare provider. Radiation exposure during pregnancy may lead to birth defects.
- If you are lactating, breastfeeding, you should tell your healthcare provider due to the risk of contaminating breast milk with the radioactive tracer.
- Tell your healthcare provider if you have a pacemaker.
- Based on your medical condition, your healthcare provider may request other specific preparation.
What happens during a resting myocardial perfusion scan?
A resting myocardial perfusion scan may be done 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:
- You will be asked to remove any jewelry or other objects that may interfere with the procedure.
- You will be asked to remove your clothing and will be given a gown to wear.
- An intravenous (IV) line will be started in your hand or arm.
- 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.
- You will lie flat on a table in the procedure room.
- The radioactive tracer will be injected into the IV in your hand or arm.
- After the tracers has circulated through your body (10 to 60 minutes depending on the type of radioactive tracer being used), the scanner will begin to 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.
- 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.
- 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.
- 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?
You should move slowly when getting up from the scanner table to avoid any dizziness or lightheadedness from lying flat for the length of the procedure.
You will be instructed to drink plenty of fluids and empty your bladder frequently for 24 to 48 hours after the test to help 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, and/or swelling at the IV site after you return home, you should notify your healthcare provider as this may be a sign of infection or other type of reaction.
Your healthcare provider may give your additional or alternate instructions after the procedure, depending on your particular situation. If the perfusion scan indicates you may have a serious or life threatening cardiac disease, your healthcare provider may talk to you about a same-day cardiovascular procedure.
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
- The risks and benefits of the test or procedure
- When and where you are to have the test or procedure and who will do it
- When and how will you get the results
- How much will you have to pay for the test or procedure