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Pediatric Heterotaxy Syndrome

What is Pediatric Heterotaxy Syndrome?

Heterotaxy syndrome is a rare, complex condition a child can be born with that involves certain organs and structures, including the heart, having formed on the wrong side of the body, or being arranged in patterns that are atypical.

In heterotaxy syndrome, the organs in the chest and abdomen are arranged in patterns that are different than normal. Multiple defects can develop, such as:

  • Missing or multiple spleens
  • Liver malfunction (biliary atresia)
  • Twisted or tangled intestines
  • Dextrocardia, in which the heart is situated on the right side of the body rather than the left side

Even within individual organs things may not be where they should be.


Isomerism (mirroring or dual structures) is common in heterotaxy syndrome.

In normal human anatomy, the left side of the body and the right side of the body are not exactly the same, and the left and right side of two-part organs (such as the lungs) are not identical.

In heterotaxy syndrome, one side of a dual organ is abnormally mirrored or duplicated on the other side (isomerism). 

In the lungs, for example, the left lobe of the lung might duplicate itself, replacing what ordinarily should be the right lobe of the lung. So, the entire lung structure is made up of two identical left lobes rather than one right and one left lobe.

What are the different types of Pediatric Heterotaxy Syndrome?

The different types of heterotaxy syndrome (isomerism) include:

Right atrial isomerism

Also called asplenia (absence of the spleen), in which dual organs mirror the right side.

Left atrial isomerism

Also called polysplenia (presence of multiple spleens), in which dual organs mirror the left side.

How does heterotaxy impact the heart?

Heterotaxy affects the heart in many different ways. 

Infants born with right atrial isomerism often have:

  • Multiple, major heart defects
  • Holes in the walls that separate the left side of the heart from the right side (septal defects)
  • Abnormalities of the heart valves
  • Blockage or abnormalities of the blood flow returning from the lungs (anomalous pulmonary venous connection)
  • Absence of the spleen (organ that filters the blood and helps the function of the immune system)
  • Liver on the wrong side of the body

Infants born with left atrial isomerism can have:

  • Holes in the walls that separate the left side of the heart from the right side of the heart (septal defects)
  • Multiple or partially developed spleens
  • Total heart block, which is a disruption of the electrical signals between the upper and lower chambers of the heart (atrioventricular block)

What are the signs and symptoms of Pediatric Heterotaxy Syndrome?

In right atrial isomerism, symptoms usually develop soon after birth and include:

  • Blue coloring (cyanosis) of the lips, nails and skin
  • Labored or difficult breathing
  • Listlessness or being limp or without energy

In contrast, infants with left atrial isomerism might not develop any symptoms until years later. In some cases, problems involving other organs such as the liver or spleen lead to the diagnosis.

How is Pediatric Heterotaxy Syndrome diagnosed?

Because of the multiple abnormal structures associated with heterotaxy syndrome, many cases can be detected before birth. Children’s Health will create a personalized care plan for your newborn.

Our echocardiography lab received accreditation from the Intersocietal Commission for the Accreditation of Echocardiographic Laboratories, which means it meets or exceeds the standard of excellence for pediatric echocardiographic studies. Ours is one of only 27 labs in the country that is certified for fetal studies.

After the birth of the infant, doctors perform different tests to further define the specific sub-type of the disorder in question and the extent of involvement of different organs.

Some tests such as X-rays are noninvasive, while others involve more complicated procedures.

What are the causes of Pediatric Heterotaxy Syndrome?

Heterotaxy syndrome develops before birth. It occurs in about one in 10,000 births and more boys than girls develop the condition.

As is the case with many congenital conditions, the exact cause of heterotaxy syndrome is unknown, but some suspected causes include:

  • Problems in the way the body of the developing fetus rotates in the womb
  • The mother having diabetes

How is Pediatric Heterotaxy Syndrome treated?

As a parent, learning that your child has been diagnosed with this condition can be overwhelming, but improved surgical techniques and expertise have raised survival rates for all patients with heterotaxy syndrome.

All infants with right atrial isomerism will need multiple major heart surgeries, done in consultation with experts from other fields (renal and hepatic, for example). All patients need continued, life-long care by cardiologists and specialists from other fields.

Pediatric Heterotaxy Syndrome Doctors and Providers