Types of Stress Testing

There are two main types of stress testing: a standard exercise stress test and an imaging stress test.

Standard Exercise Stress Test

A standard exercise stress test uses an EKG (electrocardiogram) to detect and record the heart's electrical activity.

An EKG shows how fast your heart is beating and the heart's rhythm (steady or irregular). It also records the strength and timing of electrical signals as they pass through each part of your heart.

During a standard stress test, your blood pressure will be checked. You also may be asked to breathe into a special tube during the test. This allows your doctor to see how well you're breathing and measure the gases that you breathe out.

A standard stress test shows changes in your heart's electrical activity. It also may show signs that your heart isn't getting enough blood during exercise.

Imaging Stress Test

Some stress tests take pictures of the heart when you exercise and when you're at rest. These imaging stress tests can show how well blood is flowing in various parts of your heart and/or how well your heart squeezes out blood when it beats.

One type of imaging stress test involves echocardiography (echo). This test uses sound waves to create a moving picture of your heart. An exercise stress echo can show how well your heart's chambers and valves are working when your heart is under stress.

The test can identify areas of poor blood flow to your heart, dead heart muscle tissue, and areas of the heart muscle wall that aren't contracting normally. These areas may have been damaged during a heart attack, or they may not be getting enough blood.

Other imaging stress tests use radioactive dye to create pictures of the blood flow to your heart. The dye is injected into your bloodstream before the pictures of your heart are taken. The pictures show how much of the dye has reached various parts of your heart during exercise and while you're at rest.

Tests that use radioactive dye include a thallium or sestamibi stress test and a positron emission tomography (PET) stress test. The amount of radiation in the dye is thought to be safe and not a danger to you or those around you. However, if you're pregnant, you shouldn't have this test because of risks it might pose to your unborn child.

Imaging stress tests tend to be more accurate at detecting CHD than standard (nonimaging) stress tests. Imaging stress tests also can predict the risk of a future heart attack or premature death.

An imaging stress test may be done first (as opposed to a standard exercise stress test) if you:

• Can't exercise for enough time to get your heart working at its hardest. (Medical problems, such as arthritis or leg arteries clogged by plaque, may prevent you from exercising enough.)
• Have abnormal heartbeats or other problems that will cause a standard exercise stress test to be inaccurate.
• Had a heart procedure in the past, such as coronary artery bypass grafting or placement of a stent in a coronary artery.