What is it?

Stress testing evaluates how the heart responds to an increase in work. An electrocardiogram (ECG or EKG) is taken while your child exercises on a treadmill or stationary bike.

Why is it done?

The test is done to determine how much exercise the heart and body are able to do, and to learn if any exercise limitations can be treated. It is also used to find out if chest pain, fainting or shortness of breath is related to the heart.

Results may indicate:

  • Arrhythmias (irregular heart rhythms) during exercise
  • Abnormal response by the heart and blood vessels to exercise
  • Lack of physical fitness
  • Lung disease, such as asthma

How does it work?

In a stress test, an ECG is taken while your child exercises on a treadmill or stationary bike. The ECG monitors the change in electrical activity as the test gets harder. The recordings let the doctor see the effects of increasing stress on the child's heart.

Ten electrodes are attached on leads wrapped in flexible plastic. The leads may be secured by a belt or mesh during the stress test to prevent too much movement.

A more advanced test, called a cardiopulmonary exercise test, may be performed. Your child will wear a facemask attached to a gas-flow sensor that measures the amount of oxygen and carbon dioxide used by the body during exercise.

The measurements allow the doctor to see how the heart, lungs and blood vessels work together in response to the stress of exercise.

What do we do before the test?

Your child should wear comfortable clothing for exercise, such as tennis shoes and shorts or sweats, to the test.

Do not let your child eat anything heavy or eat or drink anything with caffeine (such as cola or chocolate) for two hours before the test, because they will be pushed to exercise as hard as they can.

What happens during the test?

Before the stress test, your child will have a baseline ECG, and blood pressure readings done while sitting. If a cardiopulmonary exercise test is being done, your child will have some breathing tests done to measure lung function.

Your child will walk on the treadmill or pedal on the stationary bike, and there will be a warm-up period. Then the speed and steepness of the treadmill, or the resistance of the bike, will be gradually increased. Your child will be asked to keep going until they are unable to continue because of fatigue, shortness of breath or chest pain, or until the doctor stops the test.

After the end of the test, there will be a cool-down period of about 10 minutes, and the heart will be monitored.

Blood pressure and oxygen saturation will be monitored throughout the test.

How long does it take?

The exercise part of the test generally takes anywhere from 6 to 15 minutes, depending on your child's fitness level. The total time from setup to the end of recovery is usually about an hour.