Nuclear Stress Testing

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

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.

A nuclear stress test combines the treadmill portion with pictures (images) recorded on computerized gamma cameras. For the pictures the patient receives a small dose of a radioactive substance (isotope), which the cameras can see. The radioactive substance can be thallium-201 or technetium-99m sestamibi (Mibi).

The basic stress test requires leads on the chest to provide the EKG signal. The EKG is the electrical signal the doctor monitors during the test. 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. They will record an EKG at rest, at peak exercise, and afterwards. The doctor will ask about symptoms and how tired you feel.

At peak exercise 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 from the exercise. After resting, you will have a second set of images. For the second set, you may require a second injection of the isotope. The doctor will compare the 2 sets of pictures to determine if the study is normal or abnormal.

The choice of isotope depends on:

1. The size of the patient 2. The information requested.

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 chest diameters. Mibi also can provide pictures of heart function, which is helpful information in patients with suspected previous heart damage.

A third possibility is using 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 12pm before the test.

Take your regular medicine, including your blood pressure medicine.

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

Common Questions About Nuclear Stress Testing

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

What about radiation?
The risk from radiation exposure is comparable to that of a chest 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.

What should I wear?
Comfortable clothes and shoes.

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