What is a nuclear heart scan?

A nuclear heart scan is a type of medical test that allows your doctor to get important information about the health of your heart. During a nuclear heart scan, a safe, radioactive material called a tracer is injected through a vein into your bloodstream. The tracer then travels to your heart. The tracer releases energy, which special cameras outside of your body detect. The cameras use the energy to create pictures of different parts of your heart.

Nuclear heart scans are used for three main purposes:

• To provide information about the flow of blood throughout the heart muscle. If the scan shows that one part of the heart muscle isn't receiving blood, it's a sign of a possible narrowing or blockage in the coronary arteries (the arteries that supply blood and oxygen to your heart). Decreased blood flow through the coronary arteries may mean you have coronary artery disease (CAD). CAD can lead to angina, heart attack, and other heart problems. When a nuclear heart scan is performed for this purpose, it's called myocardial perfusion scanning.
• To look for damaged heart muscle. Damage may be due to a previous heart attack, injury, infection, or medicine. When a nuclear heart scan is performed for this purpose, it's called myocardial viability testing.
• To see how well your heart pumps blood out to your body. When a nuclear heart scan is performed for this purpose, it's called ventricular function scanning.

Usually, two sets of pictures are taken during a nuclear heart scan. The first set is taken when the heart is beating fast due to you exercising. This is called a cardiac stress test. If you can't exercise, your heart rate can be increased using medicines such as adenosine, dipyridamole, or dobutamine.

The second set of pictures is taken later, when the heart is at rest and beating at a normal rate.

This answer from the National Heart, Lung and Blood Institute has been reviewed and/or edited by Dr. William D. Knopf.

A nuclear heart scan is a special type of test that assesses the blood flow in the heart as well as then function of the heart muscle. There are different types of nuclear heart scans, the most common of which is a nuclear stress test otherwise known as a myocardial perfusion study. When a myocardial perfusion study is performed, an intravenous line is placed. A small dose of a radioactive material is injected through your vein, which enters your bloodstream. The radioactive material, otherwise known as a tracer, travels through your blood and is taken up by the heart muscle. Usually, two sets of images are needed as assessment of blood flow and trying to figure out if there is a problem or restriction in the blood flow to the heart, which may be causing chest pain or other symptoms. During one part of the test, the radiotracer is given while you are resting. The images are obtained by a special camera called a gamma camera, which detects the radiation and allows the technologist to create images of the heart that the doctor can evaluate. The second part of the test is typically during some mode of stress, usually exercise on a treadmill or a bicycle. In that situation, the radiotracer is injected through the same intravenous line when you are performing exercise. A second set of images is obtained that assesses whether the blood flow during exercise is adequate. If you cannot walk on a treadmill or use a bicycle, there are alternative methods to obtain the same information using pharmacologic stressors. These pharmacologic stressors are drugs such as adenosine, regadenoson, or dobutamine. Although these drugs do not create the exact same stress as exercise, they do create a similar situation, which gives the same information on the images.Once the physician has the rest and the stress images, he or she can compare them and tell whether there is adequate blood flow at times of stress as well as during rest. If there is abnormal blood flow at rest, it may signify a previous heart attack or other problem.