Myocardial Perfusion Imaging Overview

Myocardial perfusion imaging is a test that uses a low dose of a radioactive agent to evaluate the blood flow and function of the heart. Since blood flow to the heart is best tested when you increase the work of the heart, this test is usually done with exercise. If you cannot exercise, your doctor may use a drug that increases the work of your heart to mimic exercise.

Blood Flow Through the Heart © 2009 Nucleus Medical Media, Inc.

Prior to Test

Before the test is scheduled, let your doctor know if you have any medical conditions that may limit your ability to exercise. If you cannot exercise, your doctor may order a drug to mimic exercise. Let your doctor know if you have any of the following:

• Asthma or chronic lung disease
• Arthritis problems, especially with your hips or knees

For 24-48 hours before the test, do not eat or drink any foods or take any of the medicines listed below:

• Beverages containing caffeine (eg, coffee, tea, colas, or other soft drinks)
• Foods containing caffeine, such as chocolate (including candies, frosting, pies, cakes, cookies, cocoa, or chocolate milk)
• Over-the-counter pain relievers that contain caffeine, including Anacin and Excedrin
• Products that contain theophylline , such as Constant-T, Primatene, Quibron, Slo-Phylline, or Theo-Dur
• Dipyridamole (Persantine)

Read product labels and ask your doctor or pharmacist for more information about products you should avoid before the test.

You may be asked to avoid eating or drinking for 4-8 hours before the test.

Wear loose clothing and low-heeled shoes with rubber soles or tennis shoes.

If you smoke, you should avoid smoking for 1-2 days before the test, or at a minimum, for at least four hours before the test.

Tell your doctor if you:

• Have a history of allergies
• Are taking any medicines or herbal supplements
• Have diabetes
• Are pregnant or might be pregnant
• Are breastfeeding
• Have any prosthetic implants in your body

Description of Test

The test usually consists of two parts. One part of the test looks at the heart at rest.

The other part of the test, called “stress,” examines the heart after exercise, or after taking a drug that mimics the effect of exercise on the heart. The doctor interpreting the test will compare the exercise and resting images to evaluate the health of your heart. The order of the parts of the test will vary based on the protocol in your hospital. You will be informed if the exercise or the rest portion will be done first.

A blood pressure cuff is placed on one arm. An intravenous line (IV) is inserted into a vein on your other arm. Small, round pads (ECG electrodes) are placed on your chest and attached to an electrocardiograph. This allows the doctor to monitor your heart rhythm. Your blood pressure and heart rate are monitored before, during, and after you have exercised.

The doctor or nurse will inject a small amount of radioactive material via the IV into your bloodstream. The amount of radioactivity in these materials is very small. The radioactive tracers concentrate in the parts of the heart that have the best blood flow, and emit signals that can be detected by a special camera. Images taken by the camera show any parts of the heart that are not getting enough blood. These images are taken while you are at rest and while you exercise.

The exercise or “stress” part of the test is usually done with a treadmill. You begin by slowly walking on the treadmill, and the pace increases gradually every three minutes. As you exercise, your heart rate and blood pressure will change. At your peak exercise, the tracer is injected into the IV and you will continue exercising for another one or two minutes.

15-30 minutes after exercising, you will lie down on a special table as images are taken of your heart.

If you are unable to exercise for any reason, the doctor may use a drug that mimics the effect of exercise on the heart. If you notice any changes in the way you feel, or experience any side effects, notify the doctor who is monitoring the test.

If you have coronary artery disease , you may feel chest pain or angina during the stress portion of the test. A specialist will be nearby and may give you medicine for the symptoms or stop the test early. Let the clinician know if you have any symptoms of jaw, neck, arm, or chest pain.

After Test

You will be able to leave after the test is done.

If you receive a medicine that increases the work of your heart, you may experience symptoms of anxiety , dizziness, nausea, shakiness, or shortness of breath. Let the doctor monitoring you know if you have any of these symptoms. There is a possibility that you may experience some effects from the medicine for up to 24 hours after the test.

How Long Will It Take?

The entire test takes 3-5 hours. You may receive the entire test in one day, or you may have each part of the test on separate days.

Will It Hurt?

In general, this test should not be painful. If you were given a dilating medicine, you may feel some discomfort such as flushing, chest pressure/pain, or shortness of breath.

The doctor will compare the images taken of your heart during rest with the images of your heart during stress. If your heart is relatively healthy, there should be little or no difference between the images taken during stress and those taken at rest. If your heart has partially blocked arteries, images taken during stress will be different from those taken at rest.

RESOURCES:

American College of Cardiology
http://www.acc.org/

American Heart Association
http://www.americanheart.org/

CANADIAN RESOURCES:

Heart and Stroke Foundation of Canada
http://www.heartandstroke.ca/

University of Ottawa Heart Institute
http://www.ottawaheart.ca/UOHI/Welcome.do

References:

HeartCenter Online website. Available at: http://www.heartcenteronline.com . Accessed on May 2, 2003.

RadiologyInfo: the radiology information resource for patients website. Available at: http://www.radiologyinfo.org . Accessed on May 10, 2003.

University of Texas website. Myocardial perfusion imaging. Available at: http://www.utmb.edu . Accessed on May 2, 2003.