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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 blood flow.

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.