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, it may be done 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 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. Areas that are damaged or don't have good blood flow do not absorb the tracer. The damaged areas may be called “cold spots” or “defects.”
A stress myocardial perfusion scan assesses blood flow to the heart muscle when it is stressed. The heart is usually “stressed” from exercise. But, if you are unable to exercise, the heart can be stressed by taking a certain medicine that increases your heart rate or dilate blood vessels as would occur during exercise.
After the radioactive tracer is injected, a special type of camera is used that can detect the radioactive energy from outside the body. The camera takes images of the heart during stress and again later at rest. The two sets of images are compared.
Your doctor may order a stress myocardial perfusion scan for:
Risks of the scan may include:
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 with your healthcare provider before the procedure. 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:
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.
You may have a stress 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 stress myocardial perfusion scan follows this process:
Exercise myocardial perfusion scan:
Pharmacologic myocardial perfusion scan:
Procedure completion, both methods:
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.
Before you agree to the test or the procedure make sure you know: