What We Do

The exercise thallium test gives us information about how your heart is working. We'll watch you closely as you exercise on a treadmill so that we can measure how well your heart handles this kind of activity.

The test is very useful in checking whether there are any blocked arteries, how your heart treatment is progressing and if your heart is strong enough for surgery. It will also tell us if any recent heart surgery (like a bypass or angioplasty) has done its job and is improving your health.​

 Materials and Resources to Help You

The Patient & Family Education Program at UHN offers valuable resources to help you understand your condition.

Resources from the Patient & Family Education Program

Visit our Health Information section to find dedicated resources to help you understand your condition. Find the information you're looking for.​

 Your Procedure

How to Prepare

Please bring with you a list of your current medications. This includes prescription medications, over-the-counter medications, vitamin or mineral supplements and herbal remedies.

DO NOT eat or drink caffeinated, decaffeinated or caffeine-free products (such as soda, chocolate, coffee, energy drinks, tea, or Tylenol #1, 2 or 3) for at least 48 hours before the test.

Checking In

When you arrive at the Nuclear Cardiology Lab, check in at the reception desk. Please have the following ready:

  • Health card (OHIP card). If you do not have an OHIP card, please bring another form of government-issued photo ID (such as a driver's license, passport, or other provincial health card). Please arrive 15 minutes before your appointment.
  • Your name, address and birth date

Before the Exercise Thallium Test

When you check-in, the receptionist will give you a name band to wear. The technologist will call you when it is time for your test. You will be asked to change into a hospital gown. There are lockers for your clothes in the changing area, but you should keep your valuables with you.

When you have finished changing, a technologist will take you into the room. They will explain the procedure and ask for your consent.

During and After the Exercise Thallium Test

A technologist will first ask you questions about your medical history, do an ECG and check your blood pressure and heart rate.

Then he or she will set up an intravenous (IV) line in your arm or hand, and when you are ready you will start exercising. The treadmill will start slowly and change speed and elevation every 3 minutes. When your heart rate reaches a certain level, the technologist will inject a small amount of thallium (a radioactive tracer). You'll keep going on the treadmill for another minute.

The next step is to take pictures. You need to lie very still under a gamma camera with your arms above your head for 30 minutes.

Then you'll have a 2 to 3-hour break. You can only drink clear fluids while on break.

When you return, we will take another set of pictures, this time of your heart at rest. You'll need to lie very still again under the gamma camera – again with your arms above your head for 30 minutes. We have you keep still so that our pictures are clear. If you move, we may need to take more pictures.

The Results of Your Exercise Thallium Test

Once the test is completed, the technologist uploads your results to your records. The physician/radiologist will write a report and send it to your doctor.

The technologist cannot give you the results during your visit.

Once the report is in your health record, your doctor can review it. You will get the results of the test from your doctor.

How Long Will Your Appointment Be?

The appointment will take about 4 to 5 hours. The first part of the test will take about an hour and a half. Then after a break, the second part will take about 45 minutes.

We do everything that we can to stay on time. Unfortunately, your appointment may be delayed by unforeseen circumstances. We recommend that you come prepared for delays.​

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