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Nuclear Stress Testing with Drugs
The stress test shows if your heart receives enough blood from its own arteries to work harder, safely. Taking the stress test also helps your doctor know what type of exercise and how much is right for you.

However, some patients cannot exercise adequately. Patients with lung disease, arthritis, or disease in the leg vessels may not be able to walk. Patients with some medical conditions should not walk on the treadmill. For these patients the doctor can use a drug to effect the blood supply to the heart and simulate the effects of exercise. The drug may be persantine (dipyridamole), dobutamine, or adenosine. The drug is used with a radioactive substance (isotope) to assess the blood supply to the heart. The radioactive substance may be thallium-201 or technetium-99m sestamibi (Mibi).
The test requires leads on the chest to provide the EKG signal, just as with an exercise study. The doctor monitors your heart rate, heart rhythm, blood pressure, and looks for changes which suggest that the heart is not receiving enough blood for its needs. He/she will record an EKG at rest, at peak exercise, and afterwards. The doctor will ask about symptoms.

For the test, you will receive the drug through a needle in your arm vein. At peak effect of the drug the doctor or technologist will inject the isotope. You will then have the images recorded. These pictures may take 30 minutes. Then you must wait for about 4 hours. During this time your heart will rest. After resting, you will have a second set of images. For the second set, you may require a "booster" injection of the isotope. The doctor will compare the 2 sets of pictures to determine if the study is normal or not.

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Thallium-201 is the most commonly used isotope. It provides pictures of how good the blood supply to the heart muscle is. Mibi also provides information about blood supply.
It is particularly useful in patients with larger chests. Mibi also provides pictures of heart function, which is helpful information in patients with suspected previous heart damage.

A third possibility is the use of the combination of the 2 isotopes to obtain function and blood supply pictures. This procedure does not require the 4 hour rest period, since the resting image is taken first.