Nuclear Stress Testing with Drugs

A stress test, sometimes called a treadmill/exercise test, helps your doctor know how your heart works during physical activity. As your body works during any physical exertion, it requires more oxygen and energy. To meet this demand, the heart beats faster and harder.

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.

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.

Special Instructions

Do not eat or drink after midnight before the test.

Take your regular medicine, including your blood pressure medicine. However, if you are taking theophylline, aminophylline or other medications for breathing, you must stop them 24 or preferably 48 hours, before the Persantine test. Speak with your physician.

If you are diabetic, do not take your insulin or oral agent. Bring the medication with you.

Common Questions About Nuclear Stress Testing with Drugs

Is it safe?
There is little risk and medical professionals are present to respond to any unusual happening.

What about the radiation?
The risk from radiation exposure is comparable to that of an x-ray.

Will I need other tests?
The results of the exercise test may suggest to your doctor that you need further studies. The results may also eliminate the need for further studies.

How long will it take?
The test takes about 5 hours total.

When will my doctor have the results?
Reports are mailed the next working day. Your physician should have the results within a few days.

I take persantine routinely. Will that interfer?
Persantine tablets will not interfer with the intravenous dose used. The intravenous dose is much higher than the tablets.