What is a nuclear stress test?

A nuclear stress test, also known as a thallium stress test, myocardial perfusion scan or radionuclide test, is a diagnostic imaging test that is performed if your doctor suspects you have coronary artery disease. The test can help determine if your heart is receiving adequate blood flow at rest or while you exercise.

Why is a nuclear stress test performed?

Your doctor may recommend having a nuclear stress test if your cardiac stress test did not reveal the cause of your symptoms or if your doctor needs more information to accurately treat a diagnosed heart condition. 

What to expect during a nuclear stress test?

A nuclear stress test takes approximately two to four hours to complete. 

During a nuclear stress test, your nuclear medicine technician will inject radioactive dye (tracer) into a vein in the arm or hand. After 20 minutes, your technician will take images of your heart at rest. The camera will take a series of images that shows how blood is flowing through the heart. To determine how your heart functions under exertion, your technician will place electrodes on your chest to monitor your EKG. You will then walk on the treadmill until your heart rate reaches a target rate (approximately 7 to 12 minutes). Your technician will then inject more radioactive dye into your vein. Your doctor will monitor your blood pressure, heart rate and EKG. Some patients are not able to reach the target heart rate and are given medication to simulate exertion. After a rest period, your technician will ask you to lie down to take more images of the heart. The resting images will be compared to the images after exercising.

What are benefits of a nuclear stress test?

A nuclear stress test gives your doctor information that can help diagnose and treat your heart condition such as:

  • The size of the heart chambers
  • How effective your heart is pumping blood to the body
  • Evaluates whether you have damage to your heart
  • Determine if you have narrowing or blockages in the coronary arteries
  • Provides information to determine if you are a candidate for a cardiac rehabilitation program

What are the risks of a nuclear stress test?

Although nuclear stress tests are relatively safe, you are exposed to a small amount of radiation, so you should be aware of complications associated with the test. Complications include:
  • Allergic reaction to the radioactive dye 
  • Arrhythmias that occur during the testing 
  • Heart attack
  • Chest pain, nausea, anxiety, headache or dizziness
  • Low blood pressure

Recovery from a nuclear stress test?

A nuclear stress test is an outpatient diagnostic test. You will go home the same day and return to your daily activities unless your doctor has given you other instructions.


After the test is complete, your doctor will review your results with you.

  • Normal results
    If your blood flows normally through both tests, you most likely do not have coronary artery disease and no further testing is required.

  • Normal blood flow during rest periods, abnormal blood flow during exercise
    When your tests reveal normal blood flow during rest periods but abnormal blood flow during exercise, you may have a blocked artery (arteries). 

  • Abnormal blood flow during rest and exercise
    If your blood isn’t flowing normally during resting or exercise, you could have severe coronary artery disease.

  • Tracer dye did not reach part of the heart
    If the radioactive tracer does not appear in certain areas of the heart, you most likely have damage from a heart attack.

Your Mercy Health doctor will consult with your cardiac team to determine the most appropriate next steps if your blood flow is abnormal. You may need further testing or immediate treatment.

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