Pharmacologic Nuclear Stress Test
A pharmacologic nuclear stress test is a nuclear stress test for patients with physical limitations. The pharmacologic test may also be referenced as an adenosine stress test or a dobutamine test. This stress test is for patients that are unable to participate in the exercise portion of the regular nuclear stress test. Physically limited patients that are unable to induce “stress” using the treadmill will have it induced pharmaceutically.
Both the nuclear stress test and the pharmacologic nuclear stress test employ a radioactive substance; hence, the term “nuclear” is used. During the stress test a small amount of a radionuclide (thallium, technetium or sestamibi) is injected to allow gamma imaging. The radionuclide does expose the patient to a small amount of radiation; however, this procedure is approved and is considered safe.
Prior to your appointment, you will need to discuss the use of any prescription or over the counter medications with the doctor. If you have asthma or diabetes, you will receive special instructions. Do not consume any food or drinks that contain caffeine for 24 hours before your test. Keep in mind that chocolate contains caffeine and decaf beverages usually contain trace amounts of caffeine. On the day of your appointment, do not eat or drink anything for at least four hours prior. Wear comfortable clothing as the entire procedure will take two to three hours.
When you arrive your blood pressure and heart rate will be noted. You will be given an IV and an injection of the radionuclide. Electrodes will be placed on your chest for an electrocardiogram. After about 20 minutes, the first set of “at rest” images will be taken. For a pharmacologic stress test using adenosine, you will receive a six minute infusion of the drug. Adenosine dilates the blood vessels providing an “imitation” of exercise. Half-way through the infusion, you will receive another dose of the radionuclide. Then you receive a beverage to help enhance the images. After a short break a second set of gamma images will be taken. If the pharmacologic being used is dobutamine, it will be infused, increasing the amount, at three minute intervals until your heart rate reaches your targeted level.
There are several variations of pharmacologic stress tests. The low level treadmill adenosine stress test, for example. This test may be scheduled for physically limited patients that are able to perform low level exercise. During the test, the patient walks on the treadmill, at a very slow pace, during the six minute adenosine infusion.
When you have finished testing, a brief summary of your results may be provided. However, Dr. Alonso will evaluate all of the data and images and discuss them you later. The doctor will recommend a course of action, based on his assessment of your results.