Nuclear stress test

A nuclear stress test is an imaging test that uses radioactive material to show how well blood flows into your heart muscle while you are active as well as while you are rest.

Nuclear stress tests help diagnose coronary artery disease, which is damage to the arteries that supply your heart with blood. If you have already been diagnosed with coronary artery disease, this test will help determine how well your treatment is working.

In preparation for a nuclear stress test, you may be asked not to eat, drink or smoke for a period of time the day of your test and to avoid caffeine the day before and the day of the test. Let your provider know if you are pregnant, breastfeeding or have an implanted medical device, and ask if you can continue to take your prescription or over-the-counter medications.

The day of the test, do not apply oil, lotions, creams or deodorant to your skin. Leave your jewelry at home and wear comfortable clothes and walking shoes. If you use an inhaler, bring it with you and make sure the people doing the test know you use one.

During this test, an intravenous (IV) line will be started and a radioactive substance such as thallium will be injected through the IV into your vein. You might feel a little sting, or a flush of warmth, but most people don't have any problem with the injection.

You will lie quietly for up to an hour on a table with some large cameras surrounding it. Once the scan begins, the cameras will move around you to take pictures of your heart and determine how the well the substance traveled through your veins and heart. You may hear different sounds as the camera takes the pictures, but it is not painful.

After that part of the scan is completed, you will be hooked up to an electrocardiograph (ECG or EKG). Sticky patches are put on your chest and possibly your arms or legs, and electrodes attached. The ECG allows clinicians to monitor the electrical impulses of your heart, although no electricity is sent to you. Then, you will be asked to walk on a treadmill or use some other type of exercise machine. You will start slowly, and then the exercise rate and intensity will be increased. While you exercise, your blood pressure as well as your heart rate and rhythm will be measured. After a while, you will be given another injection through the IV, and you will lie back on the table so more pictures can be taken. If you are unable to exercise, medications will be given to you to make your heart beat faster and harder, similar to when you exercise.

These tests are very safe, but as with any medication, there is always the chance of an allergic reaction to the medications used. If you are given medications because you could not exercise, you might briefly feel anxious, dizzy, nauseated, short of breath or have some mild chest discomfort, but this should go away quickly. Let the people in the room know and they may give you other medications to stop these feelings.

The small amount of radioactive material used in the test loses its radioactivity over time. Drink plenty of water during the hours and days after the test to help flush the radioactive material out of your body. Depending on the type of radioactive material used, women who are breastfeeding and people who take care of small children may need to make adjustments after the test, such as to stop breastfeeding for a short time and avoid close contact with young children. Talk with your provider to determine if this needs to happen. No other precautions need to be taken and no one close to you is at risk from this small amount of radioactive material.

An abnormal nuclear stress test result indicates that an insufficient amount of blood is reaching your heart, at rest, with activity, or both. Restricted blood flow indicates coronary artery disease and certain results can indicate damage to the heart. If you already know you have coronary artery disease, an abnormal result may indicate that your treatment plan needs to be changed.

Whatever the results of the test, your health care provider will explain the findings and talk with you about your concerns. Both of you will develop a treatment plan to improve or manage how your heart functions.

Clinically reviewed and updated, March 2022