Definition of Nuclear stress test:

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 center or physician's office. It is done in parts, or stages:

You will have an IV (intravenous line) started.

• A radiopharmaceutical, such as thallium or sestamibi, will be injected into one of your veins.
• You will lie down and wait for between 15 and 45 minutes.
• A special camera will scan your heart and create pictures to show how the radiopharmaceutical has traveled through your blood and into your heart.

Most people will then walk on a treadmill (or pedal on an exercise machine).

• After the treadmill starts moving slowly, you will be asked to walk (or pedal) faster and on an incline. It is like being asked to walk fast or jog up a big hill.
• If you are not able to exercise, your doctor may give you a medicine called a vasodilator, which dilates your heart arteries. Or you may get a medicine 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.

When your heart is working as hard as it can, a radiopharmaceutical is again injected into one of your veins.

• You will wait for 15 to 45 minutes.
• Again, the special camera will scan your heart and create pictures.
• You may be allowed to get up from the table or chair and have a snack or drink.

Using a computer, your doctor can compare 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.

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:

• Tea and coffee
• All sodas, even ones that are labeled caffeine-free
• Chocolates, and certain pain relievers that contain caffeine

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:

During the treadmill test, some people feel:

• Chest pain
• Fatigue
• Muscle cramps in the legs or feet
• Shortness of breath

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.

If you are given medication to make your heart beat stronger and faster (dobutamine), you may have a headache, nausea, or your heart may pound more strongly.

Rarely, during the test people experience:

• Chest discomfort
• Dizziness
• Palpitations
• Shortness of breath

If any of these symptoms occur 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
• Before you start an exercise program or have surgery, if you are at high risk for heart disease or complications
• 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