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Nuclear stress test

Alternative Names

Sestamibi stress test; MIBI stress test; Myocardial perfusion scintigraphy; Dobutamine stress test; Persantine stress test; Thallium stress test; Stress test - nuclear

Definition

Thallium stress test is a nuclear imaging method that shows how well blood flows into the heart muscle, both at rest and during activity.

How the test is performed

This test is done at a medical or outpatient center. The test is done in two parts:

Part 1: Stressing the heart:

• Most people will walk on a treadmill (or pedal on an exercise machine).
• Gradually you will be asked to walk (or pedal) faster and on an incline.
• If you are not able to exercise, your doctor may give you a medicine called that will make your heart beat faster and harder, similar to when you exercise.
• Your blood pressure and heart rhythm (ECG) will be watched (monitored) the whole time.

Part 2: The health care provider will inject a radioactive substance into one of your veins and then take pictures of your heart.

• The radioactive material may be thallium or sestamibi. These substances travel through your bloodstream to the arteries of your heart, then into the heart muscle.
• Next, you will be asked to lie down on a table or sit in a special chair. A computer creates pictures of your heart by tracking the radioactive material present in your heart. These images show how blood flows to your heart during exercise.

After the first set of pictures are taken, you will be allowed to get up from the table or chair for a period of time.

You will be asked to return anywhere between 1 and 4 hours later for a second set of images.

Your doctor will compare the amount of thallium or sestamibi present in areas of your heart between the first and second set of images. This can help your doctor tell if you have heart disease or if your heart disease is becoming worse.

If your study takes more than an hour, you will usually be allowed to have a caffeine-free lunch or a snack at a nearby cafeteria.

How to prepare for the test

You should wear comfortable clothes and shoes with nonskid soles. You will probably be asked not to eat or drink anything after midnight, except for a few sips of water if you need to take medicines.

You will need to avoid caffeine for 24 hours before the test. This includes caffeinated beverages such as tea, coffee, and sodas, as well as chocolates, and certain pain relievers.

Your doctor will tell you if you need to stop taking any medicines before the test. Medications used to treat asthma and angina may interfere with test results. Never stop taking any medicine without first talking to your doctor.

It is important to tell your doctor if you have taken a dose of the following medications within the last 24 hours:

• Sildenafil citrate (Viagra)
• Tadalafil (Cialis)
• Vardenafil (Levitra)

How the test will feel

Some people feel fatigue, muscle cramps in the legs or feet, shortness of breath, or chest pain during the treadmill test.

If you are given the vasodilator drug, you may feel a sting as the medication is injected, followed by a feeling of warmth. Some patients also have a headache, nausea, and a feeling that their heart is racing.

Rarely, during the test people experience:

• Chest discomfort
• Dizziness
• Palpitations
• Shortness of breath

If any of the symptoms listed above appear during your test, let the lab personnel know immediately.

Why the test is performed

The test is done to see whether your heart muscle is getting enough blood flow, and therefore enough oxygen, when it is working hard (under stress).

Your doctor may order this test to determine:

• How well a treatment (medications, angioplasty, heart surgery) is working
• If you are at high risk for heart disease before you start an exercise program or have surgery
• The cause of new chest pain or worsening angina
• What you can expect after you have had a heart attack

The results of a nuclear stress test can help your doctor:

• Determine how well your heart is pumping
• Determine the proper treatment for coronary heart disease
• Diagnose coronary artery disease
• See whether your heart is too large

Normal Values

A normal result means blood flow through the coronary arteries is normal.

Note: Normal value ranges may vary slightly among different medical centers. Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

Abnormal results may be due to:

• Reduced blood flow to a part of the heart. The most likely cause is a blockage of the arteries that supply your heart muscle.
• Scarring of the heart muscle due to a previous heart attack

After the test you may need:

• Angioplasty and stent placement
• Changes in your heart medicines
• Coronary angiography
• Heart bypass surgery

What the risks are

Complications are rare but may include:

• Arrhythmias
• Increased angina pain during the test
• Difficulty breathing or asthma-like reactions
• Extreme swings in blood pressure
• Skin rashes

Your health care provider will explain the risks before the test.

Special considerations

Breast tissue in women and nonheart tissues such as the diaphragm can sometimes cause false positive test results when older (rest-stress) methods are used to show how well blood flows into your heart muscle. This problem has been effectively eliminated by a quantified (FHRWW) method, which can reduce the need for further testing. Further tests may include a cardiac catheterization.

References

Udelson JE, Dilsizian V, Bonow RO. Nuclear cardiology. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. St. Louis, Mo: WB Saunders; 2007:chap. 16.

Fleming RM, Harrington GM, Baqir R, Jay S, Challapalli S, Avery K, Green J. Renewed Application of an Old Method Improves Detection of Coronary Ischemia. A Higher Standard of Care. Federal Practitioner 2010;27:22-31.