How Do Cardiac Stress Tests Work?

A cardiac stress test evaluates the amount of workload that the heart can take before it develops a problem with rhythm or blood flow, explains WebMD. The different types of tests include an exercise stress test, a dobutamine or adenosine stress test, a stress echocardiogram and a nuclear stress test.

During an exercise stress test the patient is connected to an electrocardiogram, which monitors the electrical activity of the heart, explains MedicineNet. The patient walks on a treadmill or uses a stationary bike and the difficulty of the activity increases throughout the procedure. The response of the heart is evaluated with the electrocardiogram.

A dobutamine or adenosine stress test is indicated for patients who require a stress test but cannot tolerate physical exercise, according to MedicineNet. A drug is injected into the vein of the patient and creates the effect of exercise on the heart. The response of the heart is monitored with an electrocardiogram.

A stress echocardiogram is a test that involves the use of an ultrasound machine to create images of the heart during an exercise stress test or a pharmacological stress test, explains MedlinePlus. During the test the doctor can evaluate the function of the heart muscles and can see the areas of the heart that do not work well during exercise.

The nuclear stress test is a procedure during which the patient is injected with a radioactive dye through an intravenous line, according to Mayo Clinic. The dye distributes in the heart vessels and an X-ray of the heart is taken. The patient undergoes an exercise or a pharmacological stress test and another set of X-rays is taken after the test. The doctor compares the images before and after and evaluates the heart vessels for the presence or absence of inadequate blood flow.