Preparing for a 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. 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).

How the Test is Performed

It is done in stages:

  1. You will have an IV (intravenous line) started.
  2. A radiopharmaceutical, such as thallium or sestamibi, will be injected into one of your veins
  3. You will lie down and wait for 15-45 minutes
  4. A special camera will scan your heart and create pictures to show how the radiopharmaceutical has traveled through your blood and into your heart
  5. Then, most people will walk on a treadmill

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 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

  • Wear comfortable clothes and shoes with nonskid soles
  • Do not to eat or drink anything after midnight, except for a few sips of water if you need to take medicines
  • Avoid caffeine for 24 hours before the test, including: Tea and coffee, All sodas (even those labeled caffeine-free), Chocolates, and certain pain relievers that contain caffeine

Notify your doctor if you have taken a dose of the following medications within the last 24 hours:

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


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
  • Diagnose an enlarged heart