The stress test is a common test used to diagnose coronary artery disease based on how your heart works during exercise. Stress tests are also called physical stress tests, exercise tolerance tests, ergometry, stress electrocardiograms, or stress EKGs.

During the stress test, a stress echo, called an echocardiogram, may also be performed as well as a nuclear stress test, done by radioisotopes injected into the bloodstream. These studies provide more information about the heart’s structure and blood flow.

How does it work?

During the stress test, small metal discs called electrodes are worn on the chest. The electrodes are connected to wires called leads which are in turn connected to a machine that has a television screen that records the electrical activity of the heart (EKG). This screen can also display images from a stress echocardiogram and an isotope stress test. By observing this screen, physicians can record the heartbeat while the patient exercises.

Patients who are too ill to exercise are given a drug that simulates the effects of physical exercise on the body.

What can I expect?

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Do not eat or drink anything for four hours prior to the test, especially avoid caffeine, including: coffee, tea, soft drinks, chocolate, and some over-the-counter pain relievers. Also, talk to your doctor about the medications you are taking and ask if you should stop any of them before the test.

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A technician will clean with alcohol the area of your skin where the electrodes will be placed. The alcohol could be cold. The electrodes are placed on your chest and back. The electrodes are connected to an electrocardiograph that records the electrical activity of your heart. A healthy person's EKG shows a particular tracing and changes in that tracing allow specialized doctors to determine if there are any heart problems.

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They will also put a pressure cuff around your arm to monitor your blood pressure during the test.

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Before starting the test, doctors will record your blood pressure and pulse. Your resting EKG, the electrical activity of your heart before you begin to exercise, will also be recorded.

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You will wear the electrodes during the exercise and for about 10 minutes after the exercise.

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During the test, you will be asked to walk on a treadmill or ride a stationary bike. Every two to three minutes, the doctor or technician will increase the speed and incline of the treadmill or stationary bike to simulate the sensation of walking or biking uphill.

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The doctor or technician will look for changes in the EKG tracing and blood pressure levels, which could indicate that the heart is not getting enough oxygen. Other symptoms of coronary artery disease include chest pain or unusual shortness of breath when exercising.

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At the end of the test, the doctor will indicate a relaxation phase during which you will be asked to lie down or sit and rest.

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After the test, you will be able to eat, drink, and resume your normal activities.

What are stress tests?

Stress tests show how your heart responds to physical activity. When we exercise, the heart pumps faster and stronger. Some heart conditions are easier to detect when the heart is working hard.

In a stress test, how your heart works is examined while you exercise on a treadmill or stationary bike. If your health does not allow you to do this, you will be given a medicine that makes your heart beat faster and stronger as if you were exercising.

If you cannot complete the stress test in a certain amount of time, it could mean that the blood flow to the heart has been reduced. This can be caused by various heart conditions, some of them very serious.

Alternative Names: Exercise EKG, Stress EKG, Stress Echo, Treadmill Ergometry, Exercise Stress Test, Nuclear Stress Test

What are they used for?

Stress tests are often used to:

Diagnose coronary artery disease, which causes a waxy substance called plaque to build up in the arteries. This can cause dangerous blockages in blood flow to the heart.

Diagnose an arrhythmia, which causes the heart to beat irregularly.

Find out what level of exercise is safe for you.

Determine the effectiveness of the treatment, if you have already been diagnosed with heart disease.

Determine if you are at risk for a heart attack or other serious heart disease.

Why do I need a stress test?

You may need a stress test if you have symptoms of reduced blood flow to the heart, for example:

Angina, a type of chest pain or discomfort caused by insufficient blood flow to the heart.

Difficulty breathing.

Fast heartbeat.

Irregular heartbeat (arrhythmia). This can cause a fluttering sensation in your chest.

You may also need a stress test to assess your heart health if:

You are starting an exercise program.

You recently had heart surgery.

You are being treated for heart disease. The test can show if the treatment is working.

You have had a heart attack.

Your risk of heart disease is higher if you have diabetes, a family history of heart disease, or heart problems.

What happens during a stress test?

There are three main types of stress tests: exercise stress test, nuclear stress test, and stress echocardiography (EKG). They can all be done in a doctor’s office, outpatient clinic, or hospital.

During an exercise stress test:

1

Your healthcare professional places several electrodes (small sensors that stick to the skin) on your arms, legs, and chest. Before doing this, you may need to shave off excess hair.

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The electrodes are connected by wires to an electrocardiography (EKG) machine that records the electrical activity of the heart.

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Then you begin to walk slowly on a treadmill or pedal a stationary bike.

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Little by little you start walking or pedaling faster and the incline and resistance are increased.

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You continue walking or pedaling until you reach a target heart rate (number of beats per minute) set by your doctor. If you start to have symptoms such as chest pain, shortness of breath, dizziness, or fatigue, you may need to stop sooner. The test may also be stopped if the EKG indicates that you are experiencing a heart problem.

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After the test, your healthcare professional watches you for 10 to 15 minutes or until your heart rate returns to normal.

The nuclear stress test and stress echocardiography are diagnostic imaging tests. This means that they capture images of your heart while you exercise.

During a nuclear stress test:

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You lie on a stretcher.

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Your healthcare professional inserts an IV into your arm. An intravenous serum containing a radioactive dye and an imaging machine create pictures of the blood flow to your heart. It takes 15 to 40 minutes for the heart to absorb the dye.

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A special camera creates images of the heart at rest.

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The rest of the study is similar to an exercise stress test. You are hooked up to an EKG machine and then walk on a treadmill or pedal an exercise bike.

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If your health does not allow you to do this, you will be given a medicine that makes your heart beat faster and harder.

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When your heart is working at its best, you will receive another injection with the radioactive dye.

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You will need to wait 15 to 40 minutes for the heart to absorb the dye.

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Then you will exercise again and the special camera will capture more images of your heart.

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The health professional will compare the two groups of images: the heart at rest and the active heart.

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After the test, your healthcare professional will monitor you for 10 to 15 minutes or until your heart rate returns to normal.

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The radioactive dye will pass out of your body naturally through urine. Drinking lots of water helps to eliminate it more quickly.

During Stress Echocardiography:

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You lie on a stretcher.

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The sonographer rubs a special gel on a wand-like device called a transducer. The transducer is placed on your chest.

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It produces sound waves that create images of the heart and project them onto film.

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After capturing these images, you exercise on a treadmill or stationary bike as in the other types of stress tests.

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If your health does not allow you this, you will be given a medicine that makes your heart beat faster and harder.

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Then more images will be taken when the heart rate is increasing or the heart reaches its maximum exertion.

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The health professional will compare the two groups of images, of the heart at rest and in action.

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After the test, your healthcare professional will monitor you for 10 to 15 minutes or until your heart rate returns to normal.

Is there anything I need to do to prepare for the test?

You should wear comfortable shoes and loose clothing to make it easier for you to exercise. You may be asked not to eat or drink anything for several hours before the test.

If you have questions about how to prepare, ask your doctor or healthcare professional.

Are these tests risky?

Stress tests are generally safe.

Sometimes exercise or medicine that increases your heart rate can cause symptoms such as chest pain, dizziness, or nausea. During the test, you will be closely watched to reduce the risk of complications or promptly treat any problems that occur.

For most people, the radioactive dye used in the nuclear stress test is safe. In rare cases it can cause an allergic reaction. Also, the nuclear stress test is not recommended for pregnant women because the dye could be dangerous to the fetus.

What do the results mean?

A normal result means that no problems with blood flow were found. If the result is not normal, it may mean that there is a reduction in blood flow to the heart. Some of the reasons are:

Coronary artery disease.

Scarring from a previous heart attack.

Your current heart treatment is not working.

Poor physical condition (being out of shape).

If the results of your stress test are not normal, your healthcare professional may order a nuclear stress test or stress echocardiogram.

These tests are more accurate than exercise stress tests, but they are also more expensive. If these imaging tests indicate that you have a heart problem, your healthcare professional may recommend further tests or treatment.