CHECK-UP:A thallium stress test often involves running on a treadmill first, writes MARION KERR.
My father is going for a thallium stress test. What is this?
A thallium stress test is a nuclear scan which shows the blood flow through the heart muscle, both at rest and during activity.
The stress test is used to assess the heart’s response to exercise and can highlight blockages in the coronary arteries that can cause chest pain (angina).
It can also indicate how well treatments which aim to improve blood flow in the coronary arteries have worked.
Scarring of the heart muscle caused by a previous heart attack can also be seen on this type of imaging.
What’s involved?
The first part of the test involves walking on a treadmill to increase the heart rate. If the person has mobility problems and cannot use the treadmill, or if the doctor thinks it is unsafe to do so, a drug called a vasodilator may be given instead to increase the heart rate.
A radioactive substance, in this case thallium, is then injected into a vein, which travels through the blood stream and into the heart muscle.
A scan of the heart is taken and a computer creates images tracking the radioactive substance as it moves through the heart. The scan is performed shortly after the treadmill test when the heart is challenged or “stressed”.
After resting for a period, more scans are taken to show the blood flow through the heart while resting. Fasting from midnight before the test is usually required. For 24 hours before the assessment, beverages or foods which contain caffeine (coffee, tea, fizzy drinks and chocolate) should be avoided. Although medications used to treat asthma and angina can interfere with the test results, medications should only be ceased on medical advice.
Are there any side effects?
Fatigue, muscle cramps, shortness of breath or chest pain may be experienced during the treadmill test.
If a vasodilator drug is used, a stinging feeling may be noticed when the medication is injected, followed by a feeling of warmth.
Some people may also experience headache, nausea or a racing heart beat. Although symptoms are usually short lived, they should always be brought to the attention of the doctor or technician when they occur.
Complications from the test are rare but they can include an irregular heart beat, increased angina during the test, difficulty breathing, swings in blood pressure or skin rashes.