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Exercise Stress Test

What is an exercise stress test?

An exercise stress test records the electrical activity of your heart on an electrocardiogram (EKG or ECG) while you walk on an exercise treadmill or pedal a stationary bicycle. It also takes blood pressure readings while you do the exercise.

When is it used?

You may have an exercise test if your healthcare provider thinks you might have heart disease. The most common cause of heart disease is narrowing of the coronary arteries. The coronary arteries are the blood vessels that carry blood, oxygen, and nutrients to the heart. The arteries can become narrowed when substances such as cholesterol build up inside the artery. The exercise test helps check for narrowing in your arteries.

Many people with narrowing of the coronary arteries do not have any symptoms when they are resting. During exercise the heart works harder and needs more blood. If the supply of blood to the heart cannot keep up with the amount of blood the heart needs, there will be changes in the EKG. Recording the EKG before, during, and after exercise shows these changes.

This test may also be done to see if treatment for heart disease is working.

How do I prepare for the test?

  • Do not eat for 2 hours before the test.
  • Ask your healthcare provider if you should take your regular medicines before the test.

What happens during the test?

Small sticky patches or suction cups are put on your chest for the EKG. An EKG is first done while you are resting. Your blood pressure is also measured while you are resting.

If a treadmill is being used for the test, you will then start a slow walk on the treadmill. If you are using a stationary bicycle, it will be easy to pedal at first. The speed and the upward slope of the treadmill are then gradually increased, or the bicycle gets harder and harder to pedal. The EKG is watched constantly, and your blood pressure is measured at each change in treadmill speed or ease of pedaling.

Your healthcare provider will stop the test when you reach a set workload. The workload is a target heart rate that is usually at least 85% of the number 220 minus your age.

The test will be stopped earlier if:

  • Your EKG or blood pressure changes a lot.
  • Your heart rhythm becomes abnormal.
  • You have chest pain.
  • You get too tired to keep going.

How accurate is the exercise stress test?

The exercise test is not a perfect test. Some people with coronary artery disease have normal test results, and some healthy people have abnormal results.

The accuracy of the exercise test can be improved in 2 ways:

  • A radioactive chemical called a radionuclide or tracer may be injected into your arm vein at the peak of exercise. (These tracers give about the same amount of radiation as a chest X-ray.) The tracer can show the blood flow in the heart. A detector placed over the chest uses the tracer to make pictures of its path to the heart. If there is good blood flow through the arteries, the pictures will show that the heart muscle picks up the tracer. If there is decreased or no blood flow though an artery, the pictures will show heart muscle that the tracer is not reaching.
  • An echocardiogram (ultrasound images of the beating heart) may be done just before and just after exercise. If you have coronary artery narrowing, the pumping of the heart shown on the echocardiogram after exercise will not be normal. This is called a stress echocardiogram.

What are the benefits?

Exercise testing is one of the safest and most widely used tests for heart disease in the US. It is a quick way to check your heart's arteries for narrowing or blockage. Your healthcare provider may use it to help decide whether you need more costly and riskier tests.

What are the risks?

Your skin might be irritated by the adhesive on the electrode patches, but any skin irritation quickly goes away when the patches are removed.

You may develop chest discomfort during the test. In rare cases, your heart may go into a very fast rhythm that could make you collapse. To ensure your safety, your healthcare provider will keep watching you, your blood pressure, and your EKG during the test. The test team will be able to treat any problems that might happen during the test.

When should I call my healthcare provider?

Call your provider right away if:

  • You have any change or worsening of pain or symptoms after the test.

Call during office hours if:

  • You have questions about the test or its result.
  • You want to make another appointment.
Written by Donald L. Warkentin, MD.
Published by RelayHealth.
Last modified: 2011-02-10
Last reviewed: 2011-04-25
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
© 2011 RelayHealth and/or its affiliates. All rights reserved.
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