Nuclear Stress Test

Medically Reviewed By William C. Lloyd III, MD, FACS

What is a nuclear stress test?

A nuclear stress test combines imaging technology, small amounts of radioactive material, and an exercise stress test to diagnose and monitor heart problems. Your doctor may use a nuclear stress test to
diagnose coronary artery disease and assess damage from a heart attack or other heart problems. A nuclear stress test can also show how well your heart pumps blood.

A nuclear stress test, sometimes called a thallium stress test, is an important test because some heart problems can only be seen when the heart is under stress from exercising. A nuclear stress test also provides important information about how the heart is functioning. Other imaging methods, such as X-rays and CTs, do not show how the heart responds to stress.    

A nuclear stress test is only one method to monitor and diagnose heart conditions. Discuss all of your testing options with your doctor to understand which options are right for you.  

Why is a nuclear stress test performed? 

Your doctor may recommend a nuclear stress test to see if any areas of your heart are not getting enough blood and oxygen when stressed by exercise. A nuclear stress test is not a routine screening test. It cannot diagnose all types of heart conditions or predict future heart problems by itself. It provides important information about your heart health in relation to your age, physical exam, medical history, and other tests. 

Doctors use nuclear stress tests to help diagnose or monitor the following conditions:

  • Coronary artery disease (CAD), a buildup of plaque on the walls of the coronary arteries that supply blood to the heart

  • Heart attack, death of a portion of the heart muscle usually due to coronary artery disease and a blood clot that blocks blood flow to the heart

  • Heart failure, an inability of a weakened heart to pump enough blood to the body. A nuclear scan is not recommended for people with advanced heart failure.

Your doctor may also perform a nuclear stress test to:

  • Assess heart damage from a previous heart attack, injury, infection, or other problem

  • Determine if your heart can tolerate a major surgery

  • Determine if your symptoms are related to CAD. Symptoms can include chest pain, dizziness, shortness of breath, fatigue, weakness, palpitations, passing out, or feeling a pounding, racing or irregular heartbeat

  • Further evaluate abnormal heart test results, such as changes on a standard resting EKG

Who performs a nuclear stress test?

The following specialists perform nuclear stress tests:

  • Cardiologists and pediatric cardiologists specialize in conditions and diseases of the heart and blood vessels. Pediatric cardiologists further specialize in treating infants, children and adolescents.

  • Clinical cardiac electrophysiologists specialize in diagnosing and treating abnormal heart rhythms (arrhythmias) using heart and blood vessel imaging and technical procedures.

  • Interventional cardiologists specialize in diagnosing and treating conditions and diseases of the heart and blood vessels using nonsurgical, catheter-based procedures and specialized imaging techniques.

  • Cardiac surgeons specialize in the surgical treatment of conditions of the heart and its blood vessels. Cardiac surgeons may also be known as cardiothoracic surgeons.

  • Advanced heart failure and transplant cardiologists care for people whose heart failure no longer responds to conventional therapies and symptom management.

How is a nuclear stress test performed?

Your nuclear stress test will be performed in a hospital or heart clinic. The stress test takes two to five hours and generally includes these steps:

  1. You will undress from the waist up and wear a patient gown for modesty.

  2. Your care team will attach sticky, painless patches, or electrodes, to your chest, arms and legs. The electrodes are attached to an EKG machine by wires. The EKG machine records your heart’s electrical activity during the test. If you have a hairy chest, your provider may shave small areas to apply the electrodes.

  3. Your care team will also apply a blood pressure cuff to your arm.

  4. Your care team will start an IV in your arm and inject a radioactive tracer, often thallium.

  5. You will rest for about 10 minutes. Then, your team will take pictures of your heart. You will need to lie still on a padded table with your arms raised overhead as a large camera rotates around you to take the pictures.

  6. You will then exercise by walking on a treadmill. You will begin to exercise harder as the treadmill gradually moves more quickly and the incline increases. If you aren't able to exercise due to a medical condition or illness, your doctor may use a drug to simulate the effect of exercise on the heart. This is called a pharmacological nuclear stress test.

  7. When you reach your target heart rate, your care team will inject a different radioactive tracer, often technetium sestamibi (Cardiolite).

  8. Your team will take more pictures with the nuclear scanner 15 to 30 minutes later.

  9. Your care team will watch your EKG and vital signs closely throughout the nuclear stress test. The team will stop the test if abnormalities occur or if you have symptoms, such as chest pain, dizziness, or shortness of breath.

  10. You will rest briefly after the test while your care team watches your vital signs for abnormalities and checks the images to make sure they are clear.

  11. You will go home right after an outpatient nuclear stress test.

Sometimes the order of certain steps is reversed. Your team may take images after the exercise portion of the test first and resting images later.  
Will I feel pain?

Your comfort and relaxation is important to both you and your care team. You will feel a brief stick or pinch during IV insertion. You may also feel a fleeting warm sensation when the radiotracer is injected through the IV. Take a few long, deep breaths to help yourself relax. Tell your care team if any discomfort does not pass quickly.

The nuclear scanning machine never touches you and taking the images is not painful. Your positioning on the table should be comfortable. Tell your care team if you are uncomfortable or if you are having trouble breathing.

The exercise and stress test portion of the test should also be painless. Tell your care team immediately if you have chest pain or any other discomfort during or after your test.

What are the risks and potential complications of a nuclear stress test?

The nuclear scan portion of your nuclear stress test is generally safe. There is a very small increased risk of cancer due to the radiation exposure involved with a nuclear scan. Nuclear scans expose you to about as much radiation as a standard X-ray. Your care team follows strict standards for nuclear medicine techniques. They use the smallest amount of radiation possible to produce the best images. 

Allergic reactions to radiotracers are rare, and nuclear scan teams are well prepared to handle allergic reactions.

The exercise portion of your nuclear stress test has a small risk of complications that include:

Your care team will watch you closely during your nuclear stress test and will stop the test if you have any problems. Be assured that your team is trained and equipped to treat complications.
People with certain conditions should not have a nuclear stress test due to an increased risk of complications. These conditions include:

  • Inflammation of the heart muscle, also called myocarditis

  • Narrowing of the aortic valve or the aorta, the major artery that carries blood from the heart to the body

  • Pregnancy or breastfeeding

  • Recent lung infection

  • Severe heart failure, a serious inability of the heart to pump enough blood to the body

Reducing your risk of complications

You can reduce the risk or the seriousness of certain complications of a nuclear stress test by: 

  • Notifying your care team immediately of any concerns such as chest pain, palpitations, dizziness, or shortness of breath

  • Telling your care team about your complete medical history. This includes if you are currently breastfeeding, a history of allergies or heart problems, and any chance of pregnancy.

How do I prepare for my nuclear stress test?

You are an important member of your own healthcare team. The steps you take before your nuclear stress test can help your care team obtain the most accurate results. 

You can prepare for a nuclear stress test by:

  • Answering all questions about your medical history and medications. This includes prescriptions, over-the-counter drugs, herbal treatments, and vitamins. It is a good idea to carry a current list of your medical conditions, medications, and allergies at all times.

  • Leaving all jewelry and metal objects at home

  • Not eating, drinking, or using caffeine before your test as directed by your doctor

  • Notifying your care team immediately of any concerns during the test such as chest pain, palpitations, dizziness, or shortness of breath

  • Stopping or taking your medications exactly as directed by your doctor. This may include not taking beta blockers.

  • Telling your doctor and your radiologic technologist if you feel nervous or anxious about lying still or having the nuclear scan

  • Telling all members of your care team if you have any allergies

  • Telling your doctor if you are breastfeeding or if there is any possibility of pregnancy

Questions to ask your doctor

It is common for patients to forget some of their questions about a nuclear stress test during a doctor’s office visit. You may also think of other questions between appointments. Contact your doctor with concerns and questions before your procedure and between appointments.

It is also a good idea to bring a list of questions to your appointments. Questions can include:

  • Why do I need a nuclear stress test?

  • How should I take my medications before and after my nuclear stress test?

  • When and how can I expect to get my test results?

  • When can I return to my regular activities after my test?

  • What other tests or treatments might I need?

  • When should I follow up with you?

  • How should I contact you? Ask for numbers to call during and after regular hours.

What can I expect after my nuclear stress test?

Knowing what to expect after your nuclear stress test can help you get back to your everyday life as soon as possible. 

How will I feel after my nuclear stress test?

Many people return to normal activities shortly after an outpatient nuclear stress test. You should not feel ill effects or have symptoms after your nuclear stress test. Tell your doctor or care team right away of any symptoms, such as dizziness, chest pain, or shortness of breath

The radiotracer will gradually dissipate from your body over several days. You will likely need to drink extra fluids to help flush out the radiotracer. You should wash your hands frequently and flush the toilet immediately after urinating for several days to avoid exposing others to radiation as the radiotracer is washed out of your system. Follow all of your doctor’s precautions to avoid exposing others to radiation.   

The radiation in the radiotracer may set off certain security systems, such as at the airport, until it is completely gone from your body. Your care team will give you a card that explains this. Carry the card with you for several days. 

When can I go home?

Most people go home right after an outpatient nuclear stress test and speak to their doctors about the results in a few days. Sometimes, patients stay to discuss the results with the doctor and to get more tests. If you are hospitalized, you will likely stay in the hospital for further evaluation and treatment.

When should I call my doctor?

It is important to keep your follow-up appointments after a nuclear stress test. Contact your doctor if you have any concerns between appointments. Seek emergency medical care or call 911 if you have chest pain or shortness of breath.

Was this helpful?
  1. Exercise Stress Test. American Heart Association.
  2. Isotope Stress Test.
  3. Nuclear Medicine Imaging. American Society of Radiologic Technologists.
  4. Nuclear Stress Test. HeartHealthyWomen. Org.
  5. Stress Nuclear Study. American College of Cardiology.
  6. Types of Stress Testing. National Heart Lung and Blood Institute.
  7. What Is a Nuclear Heart Scan? National Heart Lung and Blood Institute.
  8. What Is an Electrocardiogram? National Heart Lung and Blood Institute.
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Nov 11
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