Nuclear Stress Test

A nuclear stress test measures blood flow to your heart muscle at rest and during stress. It is performed similar to a routine exercise stress test, but provides images in addition to electrocardiograms.

During a nuclear stress test, a radioactive substance is injected into your bloodstream. This substance mixes with your blood and travels to your heart. A special scanner — which detects the radioactive material in your heart — creates images of your heart muscle. Inadequate blood flow to any part of your heart will show up as a light spot on the images because not as much of the radioactive substance is getting there.

There are several types of nuclear stress tests, including:

• Mycocardial perusion scan. During this procedure, you exercise on a treadmill of pedal a stationary bicycle. When you reach your maximum heart rate, you’re given the injection. Images are made of your heart shortly after exercise and also a few hours later. This test shows how well blood flows into the heart muscle and can detect narrowing of the coronary arteries (coronary artery disease).
• Multiple gated acquisition (MUGA) scan. In this test, you receive the injection before exercising. Images are made of your heart before and after exercise. A MUGA scan shows the motion of the heart and how well it pumps out blood (ejection fraction).

If you’re unable to exercise, you may be injected with a medication that increases blood flow to your heart muscle, simulating exercise, for the test.