Cardiac Center

Heterotaxy Syndrome (Isomerism)

Before you begin reading about heterotaxy syndrome, please read the explanation of how the normal heart works for a basic understanding of its structure and function.

What is heterotaxy syndrome (isomerism)?

Heterotaxy syndrome is a rare birth defect that involves the heart and other organs. The beginning of the word (hetero-) means “different” and the end (–taxy) means “arrangement.”

In heterotaxy syndrome, paired organs, such as the lungs or kidneys, are often mirror images of one another instead of having the unique characteristics of right and left that are normally present.

There are different forms of heterotaxy syndrome. All usually involve heart defects, of varying type and severity. In addition, organs such as the stomach, intestines, liver and lungs may be in abnormal places in the chest and abdomen.

Asplenia and polysplenia

Here are general descriptions of two types of heterotaxy syndrome. The morphology (structure) of the heart varies from child to child. The Cardiac Center team will explain your child’s heart structure to you in detail. Types of heterotaxy syndrome include:

What do the terms “right atrial isomerism” and “left atrial isomerism” mean?

The heart has tiny pouches, one on each of the two upper chambers, called atrial appendages. In a normal heart, the left atrial appendage looks different than the right. In heterotaxy syndrome, the two appendages look similar. “Isomerism” means mirror images. Hence the terms “right atrial isomerism” and “left atrial isomerism.”


What are the symptoms of heterotaxy syndrome?

Symptoms of heterotaxy syndrome vary widely.

In nearly all cases of right atrial isomerism and some cases of left atrial isomerism, symptoms will appear when the child is born or is a few days or weeks old, because the heart defects are severe. In these cases, symptoms include:

Sometimes patients with left atrial isomerism don’t have any symptoms and the condition isn’t diagnosed until the child is older or an adult.


How is heterotaxy syndrome diagnosed?

In many cases, heterotaxy syndrome is diagnosed prenatally. The Fetal Heart Program at The Children’s Hospital of Philadelphia can monitor baby and mother throughout the pregnancy and create a plan for labor and care after the birth. CHOP has its own delivery unit, on the same floor as cardiac operating rooms and cardiac patient care units. Newborns can be in the care of pediatric cardiologists and specially trained cardiac nurses immediately.

The Fetal Heart Program team will discuss delivery in the Garbose Family Special Delivery Unit with mother and family.

After the child is born, diagnosis of heterotaxy syndrome may require some or all of these tests:

Sometimes, cardiac catheterization will be required. A thin tube is inserted into the heart through a vein and/or artery in either the leg or through the umbilicus (“belly button”).

Other diagnostic tests on other areas of the body will also be required, including renal ultrasound and abdominal ultrasound. Throughout diagnosis and treatment, your Cardiac Center team will work with the specialists, such as urologists, gastroenterologists and others, to provide the best care for this complex condition.


What are the treatment options for heterotaxy syndrome?

Treatment for heterotaxy syndrome varies depending on the severity of the heart defects.

Most patients with left atrial isomerism will require surgical procedures or catheterization to repair holes in the heart or other problems. Some patients will require implantable pacemakers or defibrillators to control abnormal heart rhythm. In rare cases, patients with left atrial isomerism won’t require any treatment; they will need to visit a pediatric cardiologist regularly for checkups.

Nearly all patients with right atrial isomerism, and some patient with left atrial isomerism, will require a series of major heart surgeries. Surgeons will reconfigure the heart and circulatory system so that the heart functions with one ventricle (pumping chamber), instead of two. This is called Fontan circulation.


What is the follow-up care for heterotaxy syndrome?

Between the Norwood and Glenn operations

Though early outcomes for patients with single ventricle heart defects after staged reconstruction have improved dramatically, the period between the Norwood procedure and the Glenn operation remains a very vulnerable time for infants. CHOP created the Infant Single Ventricle Monitoring Program to focus on the care and monitoring of infants with single ventricle heart defects between the first and second reconstructive surgeries.

Through age 18

Patients with Fontan circulation are referred to as single ventricle patients. As these patients get older, doctors are recognizing that, while some do fine, many experience complications, including lung, liver and gastrointestinal diseases. CHOP created the Single Ventricle Survivorship Program that specializes in the care of these patients, and is researching improved treatments for them.

In addition, as a group, children with complex congenital heart defects who have had open heart surgery as infants are at a higher risk for neurodevelopmental issues when compared to children without congenital heart defects. The Cardiac Center at CHOP created the NeuroCardiac Care Program (NCCP) to provide evaluation, screening and clinical care for children with complex congenital heart disease who are at risk for neurodevelopmental problems.

All children with heterotaxy syndrome will require life-long care by a cardiologist. In many cases, children with this condition will have many needs and will require care from different teams at CHOP for many years.

The family is very important in the child’s care. For instance, in patients who do not have a spleen, an infection can quickly become life-threatening. If the child develops a fever (one sign of infection), the family must take the child to a hospital quickly, as IV antibiotics may be required. Your team at the Cardiac Center will make sure you understand the steps you need to take to help keep your child safe.

Into adulthood

We will help older patients with heterotaxy syndrome transition to an adult cardiologist. The Philadelphia Adult Congenital Heart Center, a joint program of The Children's Hospital of Philadelphia and the University of Pennsylvania, meets the unique needs of adults who were born with heart defects.


Contact us

Contact the Cardiac Center at The Children's Hospital of Philadelphia for a second opinion or for more information.

Reviewed by: Meryl S. Cohen, MD
Date: July 2013

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