Nuclear Stress Test (MIBI)
What is it?
A thallium scan exercise test looks at the blood flow in the heart and is more accurate than a normal exercise test. Like an exercise test you initially walk on a motorised treadmill while you are attached to an ECG machine. The treadmill begins at a very slow speed which will be increased every few minutes. When you becoming tired or feeling pain in the chest but can still walk for another minute you should let us know so that the thallium tracer can be injected into the needle in a vein on the back of your hand. After the exercise a scan of your heart is taken under a scanner camera while you are lying down. Scanning takes about 20 minutes during which time you will need to hold your arms folded and supported your head to keep them out of the way of the scanning camera. It is necessary to stay still and breathe quietly.
How long does it take?
The walking component of the test takes about 30 minutes and then the first scan is performed which takes another 30 minutes. You will then be allowed to go home and asked to return four hours later for the second scan which takes another 30 minutes. The test result will be available to your Doctor in two or three days.
What preparation do I need:
You should fast for four hours prior to the test. You should avoid caffeine for 24 prior to the test, this includes coffee, tea, cola drinks and chocolate. Check with your Doctor.
We usually stop beta blockers (Tenonnin, Betaloc. Noten, Lopressor, Visken, Inderal, Tenlol) and Calcium blockers (Isoptin, Cordilox, Veracaps, Cardizem) for 24 hours before the test.
What are the risks?
Thallium exercise tests have an accuracy of between 85 and 95 %, meaning that in rare situations the test may fail to detect heart problems. If your chest pain persists despite a satisfactory test you should notify your Doctor who may then order more extensive testing. The risk of a stress tests is low but rarely, patients with severe disease can suffer heart attacks. You should notify us if your chest pains have been worsening or become more frequent in the days leading up to the test. At John Fawkner we have full facilities to deal with cardiac emergencies and the backup of the hospital and Coronary Care Unit if required. Occasionally the test may give an unclear result which may need further testing. Please note the injection to test blood flow contains a small dose of radioactive salt. This cannot be used if you are pregnant or intend pregnancy soon after the test. The exposure to radiation is equivalent to several chest Xrays. The benefits of doing the test should be explained by your doctor.