Definition of the Procedure
The adenosine stress test is a nuclear stress test that is used to evaluate the flow of blood to the heart. The test measures levels of blood flow to the heart during periods of activity and periods of rest to give doctors a complete picture of what is h appening with the heart. Because this test involves a radioactive tracer and a medication that dilates the blood vessels to simulate the effects of exercise on the heart, it must be done by trained technicians and the results must be reviewed by a licensed physician.
On the day of the test, you will not be able to eat or drink anything until the procedure has been completed. Small sips of water are allowed if you must take medications before you have your test. There are some substances that must be avoided so that your test results are not skewed. Caffeine and nicotine are the two substances that absolutely must be avoided. Avoid caffeinated products for 24 hours before the test and abstain from smoking on the day of the test since these substances can increase heart rate and affect blood flow to the heart. You should also avoid caffeine-free products for 24 hours before the test, as these products may contain small amounts of caffeine.
Some medications may also need to be avoided in order to avoid skewing your test results. If any of your medications contain caffeine, you should not take them for 24 hours before the procedure. Asthma sufferers should avoid taking Theo-dur for 48 hours before the test and should also bring their inhalers with them to the testing center. Diabetics may be given instructions regarding insulin dosages and meals prior to completing the test. Unless your doctor informs you otherwise, you should also avoid beta blockers, nitroglycerin, and drugs such as Isordil, Imdur, and Persantine.
At the beginning of the procedure, a technician will insert an intravenous line (IV) into a vein in your arm so that a radioactive tracer can be injected into the bloodstream. After 30 minutes, a set of images will be taken while you are at rest. You will then be placed in a lying position with both arms above your head. Using a gamma camera, a series of images will be taken to show the blood flow through your heart. Once these resting images have been taken, you will be given medication to simulate the effects of exercise on the heart.
Before the medication is given, you will be connected to an EKG machine via a set of electrodes. The technician will discss how the medicine will work and what side effects to expect. Patients who are able to walk will walk on the treadmill at a slow pace during the test. If you are unable to walk, you will lie on the exam table for the remainder of the test. After a 30-minute wait, the camera will take more images that show blood flow through your heart during a period of cardiac stress. These images will be compared to the resting images that were taken at the beginning of the test.
Cleveland Clinic. “Nuclear Adenosine Stress Test.” Accessed 30 June 2009.