Thallium stress test is a nuclear imaging method that shows how well blood flows into the heart muscle, both at rest and during activity.
This test is done at a medical center or health care provider's office. It is done in stages:
You will have an intravenous (IV) line started.
Most people will then walk on a treadmill (or pedal on an exercise machine).
Your blood pressure and heart rhythm (ECG) will be watched throughout the test.
When your heart is working as hard as it can, a radioactive substance is again injected into one of your veins.
Your provider will compare the 1st and 2nd set of pictures using a computer. This can help detect if you have heart disease or if your heart disease is becoming worse.
You should wear comfortable clothes and shoes with non-skid soles. You may be asked not to eat or drink after midnight. You will be allowed to have 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:
Many medicines can interfere with blood test results.
During the test, some people feel:
If you are given the vasodilator drug, you may feel a sting as the medicine is injected. This is followed by a feeling of warmth. Some people also have a headache, nausea, and a feeling that their heart is racing.
If you are given medicine to make your heart beat stronger and faster (dobutamine), you may have a headache, nausea, or your heart may pound faster and more strongly.
Rarely, during the test people experience:
If any of these symptoms occur during your test, tell the person performing the test right away.
The test is done to see if your heart muscle is getting enough blood flow and oxygen when it is working hard (under stress).
Your provider may order this test to find out:
The results of a nuclear stress test can help:
A normal test most often means that you were able to exercise as long as or longer than most people of your age and gender. You also did not have symptoms or changes in blood pressure, your ECG or the images of your heart that caused concern.
A normal result means blood flow through the coronary arteries is probably normal.
The meaning of your test results depends on the reason for the test, your age, and your history of heart and other medical problems.
Abnormal results may be due to:
After the test you may need:
Complications are rare, but may include:
Your provider will explain the risks before the test.
In some cases, other organs and structures can cause false positive results. However, special steps can be taken to avoid this problem.
You may need additional tests, such as cardiac catheterization, depending on your test results.
Reviewed By: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Internal review and update on 09/01/2016 by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.