What is a Nuclear Scan?
A nuclear scan is a test that uses a radioactive material like myoview, thallium or sestamibi, known as a tracer, to produce images of the heart muscle. When combined with an exercise test, the nuclear scan helps determine if areas of the heart are not receiving enough blood. NOTE: Nuclear tracer is not an iodine dye.
The exercise nuclear 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).
In most cases, doctors use two tracers during one test (dual-isotope imaging), one tracer for the rest portion (thallium) and the other for the exercise portion (myoview or sestamibi).
What Does it Show?
During the test, a small amount of myoview tracer is injected into a vein in your arm while you walk on a treadmill.
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”.
Preparing for the Test
1. Do not eat of drink for 4 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.
2. 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. Do not take beta-blocker medication (see list) for twelve (12) hours prior to the treadmill nuclear stress test. Do not take the ophylline medications (see list) eight (8) hours prior to adenosine or persantine nuclear stress test. If you are using inhalers for asthma or emphysema please bring them with you. If you have any questions regarding your medications please call our office.
3. Before the test, you’ll be given a brief explanation of the procedure and you’ll be asked to sign a consent form. Feel free to ask any questions prior to signing the consent.
4. Bring lunch. (Nothing that has to be refrigerated.) This is not for comfort, it is to induce certain physiologies at a specified time of the exam. For optimal results it is mandatory to bring lunch.
5. Wear loose and comfortable clothing that is suitable for exercise, preferably a shirt or blouse that opens in the front. Also wear comfortable flat walking shoes or sneakers.
6. 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 nuclear scan is usually performed at a hospital, office, or test center. For one-day nuclear tests the rest portion is done first, then the exercise portion. In two-day nuclear tests the rest portion is done one day and the exercise portion is done another day.
The tracer will be injected and a set of pictures will be taken, while you are at rest. 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 twenty (20) minutes. These images are compared to the images obtained during the exercise portion of the test.
You will walk on a treadmill. The treadmill moves slowly at first, then the speed and incline increase gradually. Try to exercise for as long as you are able to, because it increases the accuracy of the test.
If walking on the treadmill is not possible you will receive an injection of a vasodilator either for four (4) minutes adenosine or thirty (30) seconds lexiscan . During infusion with adenosine or lexiscan you may experience chest pain, shortness of breath, headache, nausea, etc. These symptoms are transient and can be reversed within two (2) minutes with another medication. Be sure to report any symptoms, such as chest pain or discomfort, dizziness, or severe shortness of breath.
When you reach the point where you feel you can’t exercise for much longer, let the technician know. The technician will inject the tracer into the intravenous line. You will then be asked to continue exercising for another minute or so after the injection.
Another set of pictures will be taken. These images will be compared to the images obtained during the rest portion of the test.
How Long Does it Take?
For a 1-day test allow four to five (4-5) hours for the entire test, which includes preparation, the exercise portion, imaging waiting time.
For a 2-day test allow two (2) hours for the “resting” day portion of the test and three (3) hours for the “stress” day portion of the test.
Is the Test Safe?
The radiation exposure during a nuclear 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 the doctor know.
The exercise test is also safe. A small amount of risk does exist, however, because it stresses the heart. Possible complications include abnormal heart rhythms, chest pain or heart attack. Experienced personnel are available to handle any emergency.
Your Test Results
Your doctor will discuss the test results with you during a future office visit. The test results help the doctor make an accurate diagnosis and develop a treatment plan that’s best for you.
Note: On an average a stress nuclear examination is 80% accurate and can miss coronary disease 1 out 5 times on an average. The test can also be postive even if you do not have blockages 20% of the time. In addition a negative stress test does not mean that you do not have risk for heart attacks. Your risk factor profile (family history, cholesterol smoking etc) predicts heart attacks and medicines modify this risk. At Florida Cardiopulmonary Center we take every care to discuss both positive and negative results with our patients on a follow up visit so be sure to ask us any questions on your follow up appointment
Medications not to take prior to Treadmill Nuclear Stress Test
Medications not to take prior to ADENOSINE or LEXISCAN Nuclear Stress Test
ALL OF THE ABOVE PLUS:
ATTENTION: THIS IS THE PREPARATION FOR THE NUCLEAR STRESS TEST.
Please read this instruction carefully
1. You must fast (nothing to eat or drink) for four (4) hours prior to the test on the 1-day test and on both days of the 2-day test.
2. You must bring something to eat and something to drink on the 1-day test and on both day 1 and 2 of the 2-day test. The drink must be CAFFEINE FREE. DO NOT bring low-fat or fat-free foods. We need you to eat a fatty meal to obtain accurate images. Examples of acceptable foods are peanut butter and jelly or ham and cheese sandwiches, chips, etc.
3. CAFFEINE and NICOTINE are NOT allowed for twelve (12) hours prior to the test.
4. Please pay special attention to the medications listed above. You can take all of your usual medications except for the ones that are listed above.
5. Once the test is started you will not be able to leave the building under any circumstances.
6. Wear comfortable clothing, such as loose fitting pants, T-shirts, etc. Your shirt must have NO METAL BUTTONS. Metal buttons interfere with the images and may result in an inaccurate test. Also wear tennis shoes or sneakers. DO NOT WEAR BOOTS or HIGH HEELED SHOES.