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Cardiac catheterization: A patient primer

Cardiac catheterization is a non-surgical procedure that is used to diagnose and treat many heart conditions.

Diagnostic catheterization

Pediatric cardiologists can often understand the structure of the heart by using noninvasive imaging tests, including ultrasound (echocardiography) and cardiac MRI. In some cases, certain parts of the heart are better seen using cardiac catheterization.We use cardiac catheterization to accurately measure how well your child's heart is pumping and how much blood is flowing, and to discover any evidence of scar tissue in the heart. We perform cardiac catheterization on newborns, infants, children and young adults.During cardiac catheterization, we thread a long, thin, flexible tube, called a catheter, through your child's large blood vessels and into the heart. The catheter allows us to measure pressures and draw blood samples. We use these measurements to determine how blood is flowing to different parts of your child's body. Sometimes we perform an angiogram by injecting X-ray dye through the catheter so that we can see important anatomic details of your child's heart.We may perform a cardiac catheterization on your child to:

  • Diagnose a heart problem
  • Learn more about a heart problem
  • Obtain cardiac tissue samples for biopsy
  • Conduct an invasive electrophysiology study (EP), if your child has an abnormal heart-beat, to locate the origin of the arrhythmia and determine how best to treat it
  • Treat the heart problem (interventional catheterization)

Interventional catheterization

Advances in interventional cardiac catheterization have improved outcomes for children with congenital heart disease greatly during the past 10 years. Corrective or therapeutic procedures can be performed during a catheterization to either complement a surgical procedure or treat a congenital or acquired heart defect without surgery. Specialists in the Pediatric Heart Center at UC Davis Medical Center have the experience, technology and expertise needed to successfully treat the full range of congenital heart problems in children and young adults.Some of the most common pediatric interventional catheterization procedures at UC Davis Medical Center include:

  • Closure of atrial septal defects (ASD) or ventricular septal defects (VSD)
  • Closure of Patent Ductus Arteriosus (PDA) in NICU babies
  • Balloon valvularplasty to repair:
    • Mitral valve prolapse
    • Mitral stenosis
    • Aortic stenosis
    • Pulmonary stenosis
  • Valve replacement procedures

Your child's cardiologist will discuss the best option based on your child's condition.Development of additional interventional cardiac catheterization procedures to treat other congenital heart conditions in children and adults is continuing.

Cardiac MRI 

Cardiac MRI is a painless, noninvasive test. We use it to take detailed pictures of your child's heart so that we can examine the structure and function of the heart and blood vessels. Using Cardiac MRI, we can create three-dimensional images of complex heart defects and measure how well the heart is pumping blood.Cardiac MRI is especially useful for examining anomalies (abnormalities) of the:

  • Great arteries, including vascular rings
  • Great veins, including patients with heterotaxy syndrome
  • Broncho-arterial abnormalities such as double outlet ventricles and superoinferior ventricles.


During an echocardiographic study (a cardiac ultrasound or echo), we use very high frequency sound waves to form a moving, two-dimensional picture of your child's heart on a television screen. This enables us to:

  • Identify any abnormalities in the structure of your child's heart
  • Evaluate how the heart muscle is functioning
  • Measure the speed of blood flow through the heart
  • Estimate blood pressure in the different chambers of the heart

Most of the time the pictures are taken using a noninvasive technique called transthoracic echocardiography, during which a small instrument (a transducer), is placed on your child's skin. Sometimes the pictures are taken from inside your child's esophagus using an invasive technique called transesophageal echocardiography.Echocardiography studies can be performed on children of any age and size. Echos are also used to examine the heart of unborn babies suspected of having congenital heart disease (fetal echocardiography).

Electrocardiography (ECG or EKG) 

An electrocardiogram or ECG allows us to measure the electrical activity in your child's heart. We perform an ECG by attaching electrodes (small patches) to your child's chest, arms and legs and connecting the electrodes to the ECG machine using lead wires. The ECG machine produces a printout or tracing that we examine to see if it varies from a normal tracing.The ECG helps us to determine whether your child might have certain heart problems. If your child has had a pacemaker implanted, we may use an ECG to monitor the pacemaker's function. We may also use an ECG to help us monitor the effectiveness of a heart medication your child is taking or to check his heart after he has had a heart procedure such as cardiac catheterization, heart surgery or an electrophysiology study.We will usually take a baseline or resting ECG as part of your child's physical examination. If your child has an exercise test, we compare the exercise ECG with the baseline or resting ECG to see if any changes occur with increasing stress on your child's heart.


If your child shows signs of having an abnormal heart rhythm (an arrhythmia), staff from our Electrophysiology Service will evaluate the heart's electrical system using an electrophysiology study (EPS). Arrhythmias result when the heart's electrical system functions abnormally or when there is an extra electrical connection or abnormal electrical focus in the heart.We may evaluate your child if she has experienced palpitations, unexplained dizziness or fainting (syncope) or if there is a family history of sudden cardiac death. We evaluate children who experience these symptoms, but have normal heart structures, as well as children with previously-diagnosed congenital heart disease.We perform studies using cardiac catheterization, using state-of-the-art equipment with computerized electrical stimulation and analysis systems. In an EPS, we insert three to five special catheters into your child's veins and guide these catheters to his heart. The tips of each catheter have platinum electrodes that record electrical signals from inside your child's heart as well as pace the heart from different locations.

Exercise testing 

Exercise testing is a valuable noninvasive tool that we use to identify your child's functional limits and/or or detect heart and/or lung problems. In an exercise test, ECGs are taken while your child exercises on our treadmill or stationary bicycle so that we can see the effects of increasing stress on his heart.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.)
  • Assess your child's aerobic and musculoskeletal conditioning
  • Learn how medications might affect your child's exercise performance
  • Develop an exercise plan as part of your child's overall care and treatment plan

While your child exercises, we make periodic adjustments to the treadmill or stationary bicycle so that we can monitor changes in your child's heart rate, blood pressure, oxygen consumption, carbon dioxide production and pulse oximetry as he exerts himself.