Stress Test

The thallium stress test is a diagnostic test that determines damage or potential damage to the heart. A thallium stress test is a type of imaging test that shows the amount of blood flow to the heart muscle. This stress test is typically performed in conjunction with an exercise stress test.

The thallium stress test helps determine many things including causes of chest pain, physical limitations, blockage of coronary arteries, and the extent of damage suffered by a heart attack. Medical professionals sometimes use the thallium stress test to measure the success of bypass surgery as well.

When a thallium stress test is administered in conjunction with exercise, the patient usually walks a treadmill until they reach an appropriate level of exercise. At that time, the patient is injected with thallium, which is a radioactive substance that mixes with the blood stream and shows up on medical imaging film. A special gamma ray camera is used to take images of the blood flow into the heart.

The images taken during a thallium stress test are taken in two intervals. The first is shortly after the patient reaches the optimum level of exercise, while the heart is “stressed” from physical exertion. The patient then lies very still for a period of time until the heart is at rest and another series of images are taken. The images between the stressed heart and the still heart are then compared.

In certain situations, the thallium stress test can be administered without actual physical exertion. When a patient is too ill or incapable of physical exercise, a drug is administered that increases blood flow to the heart muscle as would happen with exercise. This enables the stress test to be performed without requiring a patient to overcome physical obstacles. In most cases, this stress test helps doctors determine the information they are looking for, but some patients require a series of different stress tests to diagnose some conditions.