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Heart Center Outpatient Services

The Heart Center provides comprehensive testing, evaluation and diagnostic services for children with heart conditions. Our pediatric cardiologists specialize in working with children of all ages, even in some cases before they are born.

With 10 clinic locations across Kansas and Missouri that offer a variety of appointment times, we make it as easy as possible for families all across the central U.S. to access top-notch cardiology care for their children.

What to expect at your cardiac appointment

Our comprehensive clinics at Children’s Mercy allow you to have all the tests your child needs in one place, and in many cases, get the results the same day. Because of this, appointments can get long, so come prepared with activities to keep your child comfortable for about two hours.

Many of our common cardiac tests, such as Electrocardiogram (EKG) and Echocardiogram, are done with pictures, so they cause minimal discomfort.

All of our staff are pediatric experts who work with kids and teens every day and will help them feel at ease during tests and procedures. At least two members from your care team review every test to ensure the most accurate and thorough diagnosis and plan of care.

Children's Mercy Heart Center nurse with patient

Electrocardiogram (EKG)

A 12 Lead EKG is a test to look at the electrical activity of the heart. The test tracks the rate as well as the rhythm of the heart to look for difference that might indicate a problem. For example, it can detect whether the heart is beating too slow or too fast, or if it has extra beats that shouldn’t be there or missing beats that should be there and aren’t. The test does not hurt at all.

To perform an EKG, the technician will place 10 electrode stickers onto your child’s chest, lower arms and ankles.  The stickers feel cold and a little wet.  Next, they’ll place a wire clip at the tip of each sticker. This allows the heart rhythm to upload to the machine. The test takes approximately 5 to 10 minutes from start to finish.

Helpful tip – Please don’t apply any lotions or oils prior to this test, otherwise the stickers may not stay on.


An echocardiogram is an ultrasound study of the heart. The images from the test allow the cardiologist to evaluate the structures and function of the heart muscle and valves as well as the blood flow through the heart and connecting blood vessels.

To perform a transthoracic (“looking through the chest”) echo, the technologist applies a small amount of warm gel to the surface of the small hand-held probe called a transducer and holds it on the child’s chest while adjusting the machine’s settings and acquiring the images. The test is painless and very similar to the type of ultrasound you may have experienced during pregnancy.

A typical new patient study lasts approximately 45 minutes. You’ll be in a room with low lighting and a television or iPad available so that the child can watch an age-appropriate program. Child Life Services are also available to provide distraction with toys and conversation if your child is having difficulty during the test.

The cardiologist views the images while they are being acquired so that you will have the results of the study the same day you’re in the clinic for your appointment.

Exercise Testing

Exercise testing (also referred to as ‘stress testing’) is a valuable, non-invasive tool that can help us identify your child's exercise ability and help detect heart and/or lung problems.  During the test, we take an electrocardiogram by placing electrode stickers on your child’s chest. The stickers and sensors allow us to monitor changes in your child’s heart rate, blood pressure, and oxygen saturation. 

Depending on your child’s needs, we may also monitor oxygen consumption and carbon dioxide production by having your child wear a soft face mask, and test their pulmonary function by having your child blow into a spirometer before and after exercise testing.

We use exercise testing to:

  • Evaluate your child's congenital heart and/or lung disease

  • Evaluate your child's cardiac and pulmonary functional capacity

  • Assess your child's symptoms and activity-related problems (fainting, chest pain, exercise-induced asthma, etc.)

  • Learn how medications might affect your child's exercise performance

The test is usually done on a treadmill or stationary bicycle, depending on the child’s age, size, and ability.  The treadmill speed and grade or resistance on the stationary bicycle gets increasingly harder the longer the child exercises and your child will exercise until maximal effort is achieved (usually only lasting about 10-12 minutes).  Once the exercise portion of the test has ended, the child is allowed to rest.  The entire appointment usually takes about 1 hour.

Your child should wear comfortable, loose and appropriately fitting clothes and gym shoes (appropriate footwear is required to complete testing). 

Your child may eat and drink like normal the day of the appointment, but should not eat a large meal immediately prior to testing, and should avoid caffeinated products like coffee, tea, and soda the day of the appointment.

This test is not dangerous.  You can expect your child to get short of breath and muscle fatigue due to the level of exercise. After the test, your child may feel tired because he or she just exercised hard.

A certified clinical Exercise Physiologist will conduct the test, and other staff like our clinic nurses may also help.  You can expect results once the testing is reviewed and interpreted by a pediatric cardiologist and the exercise physiologist.

The exercise test is conducted in the Exercise Physiology Lab, which is part of the Cardiology Clinic. The location of the testing is dependent upon your child’s medical history.  

You can make an appointment by calling the Exercise Physiology Lab at (816) 234-9416. Appointments are available Monday-Friday, with Saturday clinics once a month.