Exercise Cardiolite Scan
What is a Cardiolite Scan?
A Cardiolite scan is a test that uses a radioactive substance, known as a tracer, to produce images of heart muscle. When combined with an exercise test, the Cardiolite scan helps determine if areas of the heart are not receiving enough blood.
The exercise Cardiolite scan is especially useful in diagnosing coronary heart disease, the presence of blockages in the coronary arteries (the vessels that supply oxygen-rich blood to the heart muscle).
(Other terms used to describe the Cardiolite scan include: sestamibi scan, myocardial perfusion scan, and cardiac nuclear imaging.)
Other tracers, such as thallium, may be used for this type of scan. In some cases, doctors use two tracers during one test (dual-isotope imaging).
What Does it Show?
During the test, a small amount of Cardiolite tracer is injected into a vein in your arm while you walk on a treadmill or pedal a stationary bicycle.
The tracer travels in the bloodstream, is carried through the coronary arteries, and is picked up by the heart muscle cells.
Areas of the heart muscle that have an adequate blood supply pick up the tracer right away and more completely. Areas that do not have an adequate blood supply pick up the tracer very slowly or not at all.
The tracer gives off a small amount of radiation that is detected with a scanning camera. A computer processes the information and produces images of the radioactivity distributed in the heart.
If an area of the heart receives less blood than the rest of the heart (because of a blocked or narrowed artery), it will pick up less radioactivity and will show up as a lighter area, called a "defect."
Additional Cardiolite is injected while you are at rest and another set of images is taken. This allows doctors to compare how much blood flows through the heart muscle during stress and at rest.
Either the exercise or rest portion of the test may be done first. The entire test can be completed in either one day or two separate days.
Preparing for the Test
Do not eat or drink for four hours prior to the test. This will help prevent the possibility of nausea, which may accompany vigorous exercise after eating. Sips of water are okay.
If you are currently taking any heart medications, check with your doctor. He or she may ask you to stop certain medications a day or two before the test. This can help get more accurate test results.
Wear loose and comfortable clothing that is suitable for exercise. Men usually don't wear a shirt during the test; women generally wear a lightweight blouse or hospital gown. Also wear comfortable walking shoes or sneakers.
Before the test, you'll be given a brief explanation of the test and you'll be asked to sign a consent form. Feel free to ask any questions about the procedure.
Several electrodes (small sticky patches) will be placed on your chest to obtain an electrocardiogram (ECG or EKG), a recording of your heart's electrical activity.
An intravenous (IV) line will be inserted into a vein in your arm to allow injection of the tracer during exercise.
What Happens During the Test?
The Cardiolite scan is usually performed at a hospital, clinic or test center. Either the exercise portion or rest portion of the test may be done first. The doctor or technician will inform you whether the test can be completed in one or two days.
You will either walk on a treadmill or pedal a stationary bicycle. The treadmill moves slowly at first, then the speed and incline increase gradually. If you pedal a stationary bicycle, it feels easy to pedal at first, then it gradually gets harder.
Be sure to report any sysptoms, such as chest pain or discomfort, dizziness or severe shortness of breath. Try to exercise for as long as you are able, because it increases the accuracy of the test.
When you reach the point where you feel you cannot exercise for much longer, let the doctor know. The technician will then inject the tracer into the intravenous line. You will be asked to continue exercising for another minute or so after the injection.
Next, you will lie flat on a special table under a large scanning camera. During imaging, the camera takes pictures of your heart at various angles. Remain still while the pictures are being taken. This part of the test may take up to 40 minutes.
The tracer will be injected one other time and another set of pictures will be taken while you are at rest. These images are compared to the images obtained during the exercise portion of the test.
How Long Does It Take?
Allow three to four hours for the entire test, which includes preparation, the exercise portion and imaging. Keep in mind that you may have to come back for more pictures later in the day or the next day.
In dual-isotope imaging, two tracers are used. A rest study with thallium is done first, and a stress study with Cardiolite follows soon after. The entire test can be completed in two to three hours (there is no need to come back).
Is the Test Safe?
The radiation exposure during a Cardiolite scan is small and the doses used are safe. However, if you are pregnant, suspect you may be, or are a nursing mother, be sure to let your doctor know.
The exercise test is also safe. A small amount of risk does exist, however, because it stresses the heart. Possible rare complications include abnormal heart rhythms and heart attack. Experienced personnel are available to handle any emergency.
Your Test Results
Your doctor will discuss the rest results with you during a future office visit. The test results help the doctor make an accurate diagnosis and develop a treatment plan that is best for you.