Nuclear Stress Test

A nuclear stress test measures blood flow to your heart muscle. This exam provides images that show areas of blood flow through the heart. A nuclear stress test usually involves taking two sets of images – before and after exercise.

Why it’s done:
Your doctor may recommend a nuclear stress test to:

  • Diagnose coronary artery disease. Your coronary arteries are the major blood vessels that supply your heart with blood, oxygen and nutrients. Coronary artery disease is a condition that develops when there arteries become damaged or diseased- usually due to a buildup of deposits called plaque. If you have symptoms, such as shortness of breath or chest pains, a nuclear stress test can help determine if they are related to coronary artery disease.
  • Look at the size and shape of your heart. The images from a nuclear stress test can show your doctor if your heart is enlarged and can measure the pumping function (ejection fraction) of your heart.
  • Guide treatment of heart disorders. If you’re already been diagnosed with coronary artery disease, arrhythmia or another heart condition, a nuclear stress test can help your doctor find out how well treatment is working to relieve your symptoms. It may also be used to help establish the right treatment plan for you by determining how much exercise your heart can handle.

A nuclear stress test is safe and complications are rare. But, as with any medical procedures, it does carry a risk of complications.
Potential complications include:

  • Allergic reaction
  • Low blood pressure
  • Abnormal heart rhythms (arrhythmias)
  • Heart attack (myocardial infarction)
  • Flushing sensation or chest pain

How you prepare:
You may be asked not to eat, drink or smoke the night before the nuclear stress test. Your doctor will instruct you concerning which medications to take prior to the exam.

If you use an inhaler for asthma or other breathing problems, bring it with you to the test. Make sure your doctor and the health care team member monitoring your stress test know that you use an inhaler.

Wear or bring comfortable clothes and walking shoes with you to the exercise stress test.

Read complete instructions on preparing for your nuclear stress test here.

During a nuclear stress test:
Before you start the test, a member of your health care team places sticky patches (electrodes) on your chest, legs and arms. The electrodes are connected by wires to an electrocardiogram (ECG or EKG) machine. The electrocardiogram records the electrical signals that trigger your heartbeats. A blood pressure cuff is placed on your arm to check your blood pressure during the test.

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

You then begin walking on the treadmill. As the test progresses, the speed and incline of the treadmill increases. The length of the test depends on your physical fitness and symptoms. Our goal is to have you work hard enough to achieve a heart rate equaling 85% of your predicted maximal heart rate. This, on an average, takes between six to ten minutes of exercise. You will continue exercising until you develop symptoms that don’t allow you to continue or warning signs detected by those monitoring your test, including:

  • Moderate to severe chest pain
  • Severe shortness of breath
  • Abnormally high or low blood pressure
  • An abnormal heart rhythm
  • Dizziness

Injection of radioactive material:
Once you’ve reached your maximum level of exercising, a radioactive material is injected into your bloodstream through an intravenous (IV) line, usually in your hand or arm. This substance mixed with your blood and travels to your heart. A special scanner detects the radioactive material in your heart.

After exercising, you will be allowed to eat and drink a light meal. Between 30 minutes to an hour, you’ll have a second set of images taken of your heart while lying on an imaging table. The Nuclear Cardiologist will compare the resting images and the stress images to measure the blood flow through your heart.

After a nuclear stress test you may return to your normal activities for the remainder of the day.

Your doctor will discuss the results of your nuclear stress test with you. Your results could show:

  • Normal blood flow during exercise and rest.
  • Normal blood flow during rest, but not exercise.
  • Low blood flow during rest and exercise.
  • Lack of radioactive material in parts of your heart.