Nuclear Stress Test
A nuclear stress test is conducted similarly to a routine exercise stress
test, but it involves an injection and the taking of images in addition
to electrocardiograms to show how much blood is reaching the heart. During
the test, a small amount of thallium, a radioactive substance, is injected
into the bloodstream and travels to the heart. A special camera or scanner
creates images of the heart and shows if there are any areas of inadequate
There are several types of nuclear stress tests, including:
- Myocardial perfusion scan. For this procedure, the patient exercises on
a treadmill or a stationary bike. When the maximum heart rate is reached,
the injection is given. Images gathered then show the heart under stress.
A few hours later, images are again taken, showing the heart at rest.
- Multigated acquisition (MUGA) scan. With this procedure, the patient receives
an injection before exercising. Images are taken before and after the
exercise period. A MUGA scan shows the motion of the heart and how well
it pumps out blood (ejection fraction).
Patients who are unable to exercise may be given medication to simulate
exercise for the test.