What is a thallium exercise test?
An exercise thallium scan involves includes an injection of a safe weak radioactive material (thallium or sestamibi) into a vein and two scans of the heart: one immediately following the injection and one after several hours. Used where the ECG alone may not provide diagnostic information. Instructions will be mailed to you once appointment is confirmed.
What happens during a thallium exercise test?
You will be injected with thallium or sestamibi. Adhesive electrodes will be applied and connected to an electrocardiogram (ECG) machine and blood pressure monitor, and then asked to walk on a treadmill (or cycle on a stationary bike). As your heart rate, heart rhythm, and blood pressure are monitored, the speed and incline of the treadmill (or resistance of the bike) will be gradually increased until you feel you can’t exercise anymore.
A doctor and nurse will be present, and the test may be stopped if there are any concerning changes to your ECG or blood pressure or other concerning symptoms.
After the test, a gamma camera is used to capture images of the heart for 30 minutes. This is followed by a break, and further imaging later in the day.
If you are unable to exercise at all, your referring doctor may instead request a dipyridamole thallium scan. You will be injected with dipyridamole, which will physiologically simulate exercise – your heart will beat harder and faster, just as if you were exercising. You may experience some minor side effects such as flushing or nausea.
How do I prepare for thallium exercise testing?
Wear shoes and clothing that is comfortable/appropriate for exercising, such as sneakers, shorts and a t-shirt. You will be asked to remove your shirt to facilitate use of ECG and blood pressure monitoring. Female patients may wear a bra/sports bra.
Thallium/sestamibi exercise tests at Western Cardiology are conducted in conjunction with SKG Radiology, and you will receive bills from both providers. Detailed instructions for the procedure will be provided ahead of time. You will need to:
- fast and avoid caffeine for 24 hours prior to the test
- avoid any eating, drinking, chewing, or smoking for 4 hours prior to the test, and
- take all your regular medications (unless instructed by your doctor).
How long does thallium exercise testing take?
This test is done in stages over a number of hours at SKG and Western Cardiology. You will be able to leave the hospital between the first and second imaging sessions.