Thallium Stress Test

Your doctor has ordered a thallium stress test. The purpose of this procedure is to determine whether exercise causes a decreased blood flow to the heart muscle. If so, we can determine whether the blood flow improves with rest. This is termed "reversible ischemia". This ischemia can also produce disturbances in your heart rhythm which may not be seen at rest. Prior to the procedure, you should avoid caffeinated beverages and have a light meal. Clear or full liquids would be ideal. You should wear loose-fitting pants and comfortable tennis shoes for the test. When you arrive, you will be asked to undress down to the waist. An intravenous (I.V.) line will be inserted into your hand and ECG wires will be hooked up to your chest. You will then be asked to walk on a treadmill until you experience symptoms such as chest pain or shortness of breath, or until you are too tired to continue walking. A cardiologist and a technician will be present throughout the entire test and will be monitoring your blood pressure and ECG continuously. Approximately one minute before you stop walking on the treadmill you need to let the technician know so that the thallium can be injected. Thallium is an isotope which is "taken up" by the heart. It flows more easily through non-diseased arteries.

The thallium enables blood flow to be seen on a camera. You will be laying on a table with scanners overhead. The pictures take approximately 10-12 minutes to obtain. You will then be asked to return in 3-4 hours for a second injection and more pictures after you've rested. Do not drink caffeinated beverages or eat a heavy meal prior to the second set of pictures.

If you are unable to walk on the treadmill, one of three different drugs may be used to exercise your heart. These are Adenosine, Dobutamine, or Persantine. In this case, the test is the same, except that the drugs are injected over a specific period of time, and you are not required to walk on a treadmill.