Myocardial perfusion 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 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 don't absorb it. Areas that are damaged or don't have good blood flow don't absorb the tracer.
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
After a heart attack (myocardial infarction, or MI) to look for heart muscle damage or if the heart is not 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 coronary artery disease
There may be other reasons for your healthcare provider to order 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
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. Don't 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 (ICD).
Based on your medical condition, your healthcare provider may request other specific preparation.
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:
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 IV (intravenous) line will be started in your hand or arm.
You will be connected to an electrocardiogram (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 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, doughnut-shaped machine. Some facilities may use a PET (Positron emission tomography) camera to acquire images.
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.
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 an urgent 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
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 you will get the results
Who to call after the test or procedure if you have questions or problems
How much you will have to pay for the test or procedure