Nuclear Stress Test

A nuclear cardiac stress test helps diagnose and monitor heart problems such as coronary artery disease (CAD). A nuclear medicine technologist injects a small amount of radioactive tracer (radiopharmaceutical) into your bloodstream. When the radioactive tracer is administered intravenously, it allows visual assessment of coronary blood flow and perfusion to the cardiac muscle. The nuclear medicine technologist will image your heart with a nuclear medicine (gamma) camera. The test has two phases: once when you’re resting and again after exercise.

The test may also be called:

• Cardiac SPECT/CT (single-photon emission computed tomography)
• Myocardial perfusion imaging (MPI)
• Nuclear stress test

Types of nuclear cardiac stress tests

A nuclear stress test can be performed by physical activity (treadmill) or medication (pharmacologic) to stress the heart. The cardiac provider team will help determine the safest or best option for you, based on EKG, history, and mobility.

• Exercise stress test: You exercise on a treadmill to increase blood flow to the heart and reach a target heart rate.
• Pharmacologic stress test: If you can’t exercise, have limited exercise capacity, or have an abnormal EKG, you will receive medication to increase blood flow and stress the heart.

What does a cardiac nuclear stress test show?

Cardiac stress testing is commonly used to diagnose and monitor coronary artery disease (CAD) by showing blood flow to your heart. CAD occurs when blood vessels are clogged or blocked.

The test can also:

• Determine whether your heart muscle is pumping well
• Identify poor blood flow
• Locate blocked arteries
• Show whether your heart has been damaged (for example, by a heart attack)

It also may be used in people with:

• Acute coronary syndrome
• Bundle branch block
• Congestive heart failure
• Other confirmed or suspected heart problems
• Trouble breathing

Who performs a nuclear cardiac stress test?

Cardiologists (heart doctors) often order this test. A nuclear medicine technologist can perform the test, along with a cardiac provider and other healthcare professionals.

What’s the difference between a stress test and a nuclear stress test?

A regular exercise stress test and a nuclear stress test are similar. Both assess your heart’s electrical activity using an electrocardiogram (EKG). Both evaluate how your heart performs under stress. But a nuclear stress test is a more advanced method that provides more detailed information.

An exercise stress test uses only an EKG to monitor your heart while you’re resting and then exercising. But a nuclear stress test includes images of your heart. A radioactive tracer is injected into your veins, and a special camera takes pictures of your heart before and after exercise.

How do I prepare for a nuclear cardiac stress test?

Your healthcare provider will give you specific instructions to help you prepare for the test. The instructions may include:

• Avoid foods, beverages and medications that contain caffeine for 12 hours before the test. Examples include coffee, tea, soft drinks, Excedrin medication, and chocolate. This includes decaffeinated versions of coffee, tea, and soda which have enough caffeine to alter the accuracy of your test.
• Bring anything with you that helps you breathe, such as your inhaler
• Fast (don’t eat or drink anything but water) for a few hours beforehand
• Inform your healthcare provider about any medications you take, including prescriptions, over-the-counter medicines, illegal drugs and supplements
• Wear sneakers and comfortable, loose clothes

Your healthcare provider may ask you to skip certain medications before the test or change the dose. But don’t change the way you take prescription medications without talking to your doctor first.

What can I expect during a nuclear stress test?

Your nuclear stress test will be performed at Goshen Hospital.

A healthcare provider will:

1. Insert an IV into your arm to inject the tracer into your bloodstream
2. Wait approximately 30 minutes for the tracer to circulate and reach the heart
3. Place patches called electrodes on your skin, usually on the chest, arms and legs (They may have to shave some hair so the patches stick.)
4. Connect the patches to an EKG machine to measure the heart’s electrical activity
5. Put a cuff on your arm to monitor your blood pressure
6. Ask you to lie on a table and stay still so they can take pictures with a special camera (You will lie on your back with your arms up by your head.)
7. Instruct you to exercise on a treadmill, starting slowly and then increasing the intensity
8. Ask you to keep exercising until you reach a target heart rate or experience bothersome symptoms (You can stop the test anytime you aren’t comfortable continuing.)
9. Inject more tracer into your bloodstream
10. Ask you to lie down on a table again to take a second set of images after exercise and a break, where you may eat and drink again

What if I can’t exercise for a nuclear stress test?

If you have a medical condition that prevents you from exercising, a healthcare provider can inject a medication into your arm. The medication stimulates the heart and increases blood flow to mimic exercise conditions.

How long does a nuclear stress test take?

A nuclear stress test usually takes about three or four hours.

What should I avoid after a nuclear cardiology stress test?

People usually can go back to normal activities immediately. You may want to drink plenty of fluids to help flush the tracer out of your body.

What are the risks of nuclear stress testing?

Nuclear stress tests are generally safe. But the procedure can cause a problem in about 1 in 5,000 people, such as:

• Arrhythmia
• Chest pain
• Heart attack (myocardial infarction)
• Low blood pressure (hypotension)

The procedure involves a small amount of radiation exposure. Radiation exposure can cause cancer, but scientists believe that requires large or frequent doses.

You should not have a nuclear stress test if you have certain conditions that are severe or not controlled, such as:

• Angina
• Aortic dissection
• Aortic stenosis (narrowed aorta).
• Arrhythmia.
• Congestive heart failure.
• Heart infection
• Pulmonary embolism
• Pulmonary hypertension

Results and Follow-Up

When will I know my nuclear cardiac stress test results?

Results of a nuclear stress test will be sent to your ordering provider within two business days. A healthcare provider such as a cardiologist or radiologist must review the images and interpret the results.