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Just hearing the words 'heart defect' or 'high blood pressure' can leave you reeling from the questions in your head and the fear in your heart. Testing and diagnostics are the first steps toward answering those questions and helping to turn fears into an action plan.

Whether your physician suspects that your child has a serious illness, or your child has already been diagnosed and you are seeking a second opinion, the cardiovascular team at Cook Children's is here to walk you through each process and support you, your child and your family every step of the way.

The sophisticated testing and diagnostic tools at Cook Children's enable specialists to identify specific ailments and disorders and to determine the best course or courses of care, depending on the results of the diagnoses. The types of testing your child undergoes will be determined by his or her current symptoms as well as a history of past illnesses and symptoms. Clinical specialists will examine the prescribed tests to find and diagnose the cause of your child's symptoms. Testing protocols may include:


Cook Children's three-dimensional lab for the planning and printing of congenital heart disease (3D aPPROaCH Lab) uses advanced technology to support pre-surgical planning and family education for patients with complex heart conditions. This is accomplished through the use of both 3D virtual viewing and 3D printing. Cook Children's is one of the only pediatric healthcare facilities in the United States to combine these technologies.

The benefits of this technology include:

  • Comprehensive three-dimensional understanding of a patient's anatomy.
  • More informed or detailed surgical or interventional plan.
  • Virtual surgery or catheterization procedures.
  • Less time in the operating room, leading to fewer complications.
  • Possible reduction in follow up surgeries or catheterizations.
  • Improved survival rates in complex cases.
  • Family consultation and education.

Learn more about the 3D aPPROaCH lab

Cardiac catheterization

Cardiac catheterization allows us to look inside certain parts of the heart. It is an excellent tool for testing and diagnosis. It can also be used to treat many heart conditions, sometimes during the testing and diagnostic procedure.


A cardiac catheterization testing is performed on newborns, children, teens, and adults to measure how well the heart is pumping, the volume of blood flowing through your child's veins (too fast, too slow) and if there is any scar tissue in the veins or heart.

During the procedure a catheter (a thin, flexible wire) is inserted into a blood vessel, then guided toward the heart. Once the catheter is in place, x-rays and other tests are done to help the doctor see how well the heart is working. Tests are done to:

  • Collect tissue for a biopsy
  • Diagnose a problem with the heart
  • Get a more specific view of a heart problem
  • Locate an arrhythmia
  • Treat the heart problem through interventional cardiac catheterization

For certain testing and interventional procedures, your doctor may create a real-time view of your child's heart through 3-D mapping and imaging. This procedure can also provide real-time data on the electrical activity in your child's heart.


Thanks to rapid advancements in technology, cardiac catheterization has been instrumental in greatly improving the testing, diagnosis and treatment of infants, children, teens and young adults with both congenital and acquired heart conditions. In many instances the doctor can perform corrective or therapeutic procedures during the same visit as the testing and diagnosis. This allows for faster treatment, requires no surgery reduces stress on the child. Our medical team is very experienced in interventional cardiac catheterizations, both for testing and for treatment. You can learn more about our interventional cardiac catheterization services here.

Learn more about the Cardiac Catheterization Program

Cardiac magnetic resonance imaging (cMRI)

The Cardiac Magnetic Resonance Imaging (cMRI) Program at Cook Children's was developed and is led by pediatric cardiologist Steve Muyskens, M.D. The clinical program performs and interprets cMRI in cardiology patients of all ages and with all types of heart disease. Magnetic resonance imaging (MRI) is noninvasive and takes pictures of the heart and surrounding structures using a large magnet, radiowaves and a computer. Additionally, the imaging is obtained without using radiation. MRIs are performed to evaluate the structure and function of the heart and blood vessels and may provide cardiologists with information that cannot be obtained by other tests.

Indications where a cMRI may be ordered include:

  • Evaluation of cardiovascular anatomy and function in patients with poor echocardiographic windows
  • Evaluation of heart and blood vessels before and/or after cardiac surgery
  • Evaluation of left and right ventricular volume, mass and ejection fraction
  • Quantification of blood flow through valves and shunts
  • Anomalies of the systemic and pulmonary veins
  • Assessment of cardiac tumors
  • Evaluation of myocardial and pericardial disease, like arrhythmogenic right ventricular dysplasia and constrictive pericarditis
  • Assessment of myocardial viability using post-gadolinium delayed myocardial enhancement

Learn more about our cMRI program

Fetal MRI

Due to its excellent detail, a fetal MRI, when combined with ultrasound, can help to provide a more accurate diagnosis. Fetal MRIs are noninvasive and do not use any radiation, which is safer for both mother and baby.

Information about the Fetal MRI program


Echocardiography uses ultrasound, or high frequency sound waves, to view the heart. This is a safe (non-radioactive) noninvasive test. There are no probes or needles, so your child won't have any discomfort during the test. Echocardiography is an excellent test for measuring the size of heart chambers and the thickness of the wall, how well the blood is pumping through the heart chambers and the functioning of the heart's valves. This test can detect abnormalities such as holes, heart masses, valve shape and any narrowing or weakening, and if there is fluid surrounding the heart.

Did you know ...
Our Echocardiography Lab director is one of only a few American Registry for Diagnostic Medical Sonography fetal registered sonographers in Texas? And that's only one way Cook Children's is leading the way in this breakthrough technology.

Younger children and children and teens who have trouble remaining still may require mild sedation. If your child is going to be sedated he or she will probably need an empty stomach, Your medical team will provide you with instructions prior to the test on when to stop feeding your child solids, and what liquids, if any, can be given and when.

Transesophageal echocardiography (TEE)

Like echocardiography, transesophaeal echocardiography uses ultrasound waves to create detailed pictures of your heart and the arteries that lead to and from it. However, the echo transducer that produces the sound waves is attached to a thin tube that passes through your child's mouth, down the throat and into the esophagus. The esophagus is very close to the heart so the sound waves are stronger and give much detailed images of the heart's upper chambers.

Doctors use TEE to find problems in the structure and function the heart in a newborn, child, teen or young adult. TEE can give clearer pictures of the upper chambers of the heart, and the valves between the upper and lower chambers of the heart, than standard echocardiograms. Your doctor may also use TEE if your child has a thick chest wall, is obese or is using a ventilator to help them breathe. The detailed pictures provided by TEE can help doctors see:

  • The size of your child's heart and how thick the heart walls are
  • How well your child's heart is pumping
  • If there is abnormal tissue around the heart valves that could indicate bacterial, viral or fungal infections, or cancer
  • If blood is leaking backward through the heart valves (regurgitation) or if the valves are narrowed or blocked (stenosis).
  • If there are any blood clots in the heart's chambers, in particular the upper chamber

TEE is often used to provide information during surgery to repair heart valves, a tear in the aorta or congenital heart lesions. It's also used during surgical treatment for endocarditis, a bacterial infection of the inner lining of the heart

Stress echocardiograph

A stress echocardiograph is usually performed to see if blood is flowing properly to and through your child's heart, as in coronary artery disease. The stress echocardiogram is done both before and after your child's heart has been stressed, either by exercise or by an injection of medicine that stresses the heart by making it beat faster and work harder.

Echocardiography charts

Echocardiography at Cook Children's

Fetal echocardiography

Fetal echocardiography is a test that is done while the baby is still in the womb. It is usually done during the second trimester of pregnancy, at about 18-24 weeks. The procedure is similar to that of a pregnancy ultrasound. The test can be performed on your belly (abdominal ultrasound) or through your vagina (transvaginal ultrasound).

In an abdominal ultrasound, the person performing the test places a clear, water-based gel on your abdomen, or belly, and then moves a hand-held probe over the area. The probe sends out sound waves which bounce off the baby's heart and create a picture of the heart on a computer screen.

In a transvaginal ultrasound, a much smaller probe is placed into the vagina. A transvaginal ultrasound can be done earlier in the pregnancy and produces a clearer image than an abdominal ultrasound.

Why the test is done

This test is done to detect a heart problem before the baby is born. It can provide a more detailed image of the baby's heart than a regular pregnancy ultrasound. The test can show:

  • Blood flow through the heart
  • Heart rhythm
  • Structures of the baby's heart

There are a variety of reasons your doctor may refer you for a fetal echocardiograph, some of the most common are:

  • A sibling or other family member had a heart defect or heart disease
  • There is a family history of congenital heart defects
  • A routine pregnancy ultrasound detected an abnormal heart rhythm or possible heart problem in the unborn baby
  • The mother has type 1 diabetes, lupus or phenylketonuria
  • The mother has rubella during pregnancy
  • The mother used street drugs or alcohol during pregnancy
  • The mother has used certain medications that may present a risk factor
  • An amniocentesis revealed a chromosome disorder

Getting the test results

If your test shows normal results it means that the echocardiogram finds no problems in your unborn baby's heart.

If the test results are abnormal it may be due to:

Depending on the symptoms, the test may need to be repeated for both normal and abnormal results. Some heart defects cannot be seen before birth, even with fetal echocardiography. These include small holes in the heart or mild valve problems. Sometimes it may not be possible to see every part of the large blood vessels leading out of the baby's heart. If the health care provider finds a problem in the structure of the heart, a detailed ultrasound may be done to look for other problems with the developing baby.

Learn more about the Fetal Echocardiography Program

Electrocardiography (EKG)

Electrocardiography (EKG) measures the heart's electrical activity to help evaluate its function and identify any problems that might exist. The EKG can help determine the rate and regularity of heartbeats, the size and position of the heart's chambers, and whether there is any damage present.

An EKG is noninvasive and there is no pain involved. Small electrodes are placed on the skin of your child's shoulders, chest, wrists and ankles. Then your child will be asked to hold still, and maybe even to hold their breath briefly while heartbeats are recorded onto a long sheet of paper, creating a wave graph. The graph shows how many beats, how strong the beats, and if there are extra or missing beats. The doctor will read the waves on the graph in the following way:

  • The number of waves per minute on the graph is your child's heart rate
  • The distance between the waves is the heart rhythm
  • The shapes of the waves show how the heart's electrical impulses are working, size of the heart and how well the different components are working together

In a healthy heart the waves are consistent and even. Abnormalities your doctor will be looking for are:

  • Slow and fast heart rates
  • Inconsistent rhythm patterns
  • Conduction blocks (short-circuits of the heart's electrical impulses that cause rhythm inconsistencies between the upper and lower chambers)

Your doctor will also look for four types of heart damage:

  • Ventricular hypertrophy – an abnormal thickening of the heart muscle
  • Ischemia – caused by an abnormally decreased blood supply
  • Cardiomyopathies – abnormalities in the heart muscle itself
  • Electrolyte and drug disturbances – these can alter the heart's electrochemical environment

Holter monitoring

Holter monitoring makes it possible for your child's medical team to track, measure and review his or her heart activity during their normal routine. The monitor is put on by a technician and then worn for a specific period of time, usually between 12 and 24 hours. During this time, your child should follow their regular routine so that the monitor gives the doctors a more accurate reading.

Who needs this test?

Holter monitoring is usually given to kids, teens and young adults with:

  • Palpitations, which is when the heart feels like it is racing (beating very fast) and or pounding (beating fast and working hard).
  • Irregular heartbeats, such as skipping beats or having extra beats, like murmurs.
  • Syncope or fainting spells.
  • Congenital heart defects.
  • A need for follow-up after a surgical procedure.

How does the test work

A technologist places small, sticky "patches" on the skin of your child's chest. The patches contain electrodes. Small wires, called lead (leed) wires, attached to a battery-operated monitor are connected to the electrodes by the technician. The monitor contains a small digital recorder that records your child's heart activity during his or her normal routine. The monitor is lightweight and portable.

A technologist places small, sticky "patches" on the skin of your child's chest. The patches contain electrodes. Small wires, called lead (leed) wires, attached to a battery-operated monitor are connected to the electrodes by the technician. The monitor contains a small digital recorder that records your child's heart activity during his or her normal routine. The monitor is lightweight and portable.

During the test, it is important that your child go about his or her normal daily routine: school, sports, exercise, play, etc., unless your doctor has advised you to avoid certain activities. Once the monitor is connected, the technician will give you instructions on:

  • Keeping the electrodes attached to your child's skin.
  • How to check the monitor for problems.
  • Who to call should you need help with the monitor.
  • How to keep the electrodes dry, including excessive perspiration (sweat) and not showering or tub bathing during the test (depending on your circumstances, you may be able to give your child a sponge bath).

The technician will also ask you to keep a diary of your child's activity during the test and any symptoms your child may experience during specific activities. For instance: note when they are sitting, exercising, playing, etc. If they have a symptom, you will write down what the symptom is (fainting, dizziness, unusual heartbeat, etc.) and what they were doing when the symptom began. You will also want to note how long the symptom lasted and what they were doing when it stopped. Your technician will go over the diary sheet with you in detail so that it will be easy to understand. In addition, there is a button on the Holter monitor which should be pushed if a symptom occurs. This will create a digital mark in the recorder that the doctor can see and review.

Are there any risks?

The Holter monitor is noninvasive and it's battery operated. The only risk is having to take the test over if the test is interrupted because:

  • The electrodes fall off or become disconnected for a long period of time. For this reason, it is very important to check the connections throughout the day. When preparing you and your child for the test, the technician will discuss what to do to prevent the electrodes from falling off, and what to do if they fall off.
  • The monitor gets wet because the digital recorder inside could be damaged by the water. Your technician will discuss with you the importance of keeping the monitor dry. In most cases, your child can sponge-bathe during the test period.

Test results

Most parents want to know when they will get the test results. When you return the monitor and the diary, your technician will create a report for the doctor who ordered the test to review and interpret the results. Typically, this takes 3-5 days. Once the review is complete, the doctor will contact you to discuss his or her findings and, if necessary, schedule an appointment to discuss any treatment that your child may need.

Transtelephonic ECG

Children, teens and young adults who experience atrial fibrillations are sometimes at an increased risk of stroke. That's because some fibrillations may cause a blood clot to form in the atria. If the clot becomes dislodged, a stroke can result.

Because fibrillations vary in frequency, length of time and level of severity, diagnosing an atrial fibrillation in children, teens and young adults using a traditional electrocardiogram (ECG) can be challenging. For patients whose atrial fibrillations don't happen on a regular basis, it's not always possible to capture an episode during a traditional ECG visit. In these cases, a transtelephonic ECG can play an important role in helping to diagnose fibrillations.

A transtelephonic ECG is a small portable electrocardiogram, sometimes called an event monitor because it can record an atrial fibrillation event as it is happening. Because it is portable, it can go where the patient goes. The device can be used at home, school and for teens and young adults, while at work.

When an event happens, it is recorded by and stored in the monitor and can be transmitted by phone to your doctor. The device is typically used for up to 30 days.

Stress (exercise) test

Adults aren't the only ones who benefit from a stress, or exercise, test. This type of testing can be very beneficial in determining how well a young heart works at different levels of activity. This test is noninvasive and for kids it can actually be quite fun. It also offer valuable information to your child's doctor. Stress testing can help to determine how well your child's heart is functioning and may signal a need for medical or surgical care. If your child has already been treated for a heart condition, your doctor may stress testing as a way to see how well the heart is functioning after treatment. In some cases where your child is experiencing chest pain, your doctor may recommend a stress test to determine if the pain is caused by the heart and vascular system, or by the respiratory system.

Who gets tested?

Children, teens and young adults who are able to walk and run on a treadmill, and can follow the instructions necessary to complete the test are good candidates. Most patients are able to participate if they are over 5 or 6 years old.

Appointments and referrals

Rare and complex congenital heart defects don’t always present a clear cut method of treatment. Often, there are multiple ways of approaching the diagnosis. Our physicians also are available to provide second opinions for families seeking alternative treatment options. If you would like to schedule an appointment, refer a patient or speak to our staff, please call our offices at 682-885-2140.