Heterotaxy Syndrome

Heterotaxy syndrome occurs when the heart and other organs are in the wrong place in the chest and abdomen. This complex heart condition also commonly affects the lungs, liver, spleen, stomach and intestines.

What is Heterotaxy Syndrome?

Heterotaxy syndrome, also called isomerism, occurs when the heart and other organs are in the wrong place in the chest and abdomen. This complex heart condition commonly affects the lungs, liver, spleen, stomach and intestines.

There are two types of heterotaxy syndrome:

  • Right atrial isomerism – This type involves many different heart defects. Children may have problems with the way their heart is made. This may include valve issues or holes in the walls dividing the heart, also known as septal defects. Blood flow from the lungs to the heart may be irregular. The spleen may also be missing, and other organs may be in the wrong place.
  • Left atrial isomerism –Children with this condition may have a problem with the heart’s electrical system, along with structural defects. Some cases involve heart block. This happens when the upper and lower heart chambers cannot send or receive electrical signals. Those with this condition may have many small spleens or none at all.

Heterotaxy syndrome affects a reported 1 in 10,000 births worldwide. However, some researchers believe it is more common than that because the condition is sometimes diagnosed later in life.

What are the Symptoms Associated with Heterotaxy Syndrome?

Each case of heterotaxy syndrome is unique. Signs and symptoms can be very different, depending on the organs involved and the severity of the condition. 

Many problems are associated with heterotaxy syndrome, including:

  • Heart defects – This includes abnormal position of the heart and/or blood vessels, structural problems, blood flow blockages and irregular heartbeats.
  • Lung problems – Includes problems with the structure of the lungs or hairs that clear mucus (cilia).
  • Malrotation of intestines – This is an abnormal twisting of the intestines
  • Liver dysfunction – This includes a serious condition affecting the way food is digested called biliary atresia.
  • Immunity problems – There is an increased risk of infection due to a missing or abnormal spleen.
  • Other irregularities – This includes defects of the skeleton, central nervous system and urinary tract.

Nearly all babies with right atrial isomerism, and some children with left atrial isomerism, show symptoms shortly after birth. Common symptoms include:

  • labored breathing
  • fast or slow heart rate
  • heart murmur
  • low oxygen level
  • problems feeding or digesting, including vomiting
  • bowel blockage
  • poor weight gain
  • blue or purple tint to lips, nails and skin
  • lack of energy or sleepiness
  • frequent infections

Some children with left atrial isomerism do not have any symptoms.

What Causes Heterotaxy Syndrome?

The cause of heterotaxy syndrome is not fully known. Some cases may be linked to genes or prenatal risk factors, such as smoking and certain diseases. The condition can run in families. About 10 percent of those affected have a close relative with a congenital heart defect.

How is Heterotaxy Syndrome Diagnosed?

Heterotaxy syndrome may be diagnosed before or after birth or much later in life. Many cases are found during a routine ultrasound that shows one or more misplaced organs.

If the condition is suspected during pregnancy, other tests may be done, including:

  • Anatomy ultrasound – A high-resolution ultrasound to confirm the diagnosis and find other problems with the organs.
  • Fetal MRI – Non-invasive imaging to get clear pictures of the affected organs.
  • Fetal echocardiogram – A special ultrasound to look at the way the baby’s heart is made and works.

Testing after the baby is born may include:

  • Chest X-rays
  • Echocardiogram
  • Electrocardiogram – A test to measure the heart’s electrical activity.
  • Holter monitor – A 24-hour test to look at the heartbeat.
  • Cardiac MRI – A test that shows three-dimensional (3D) pictures of the heart.
  • Cardiac catheterization – S procedure where a thin tube is inserted into the heart through a blood vessel in either the leg or belly button to check pressures in different areas of the heart.
  • Other diagnostic tests – These tests include blood tests, renal (kidney) ultrasound, abdominal ultrasound, lung tests and/or an upper gastrointestinal (GI) study.

When the child has no symptoms, the problem may be found during the teen years or adulthood when they are having tests done for other reasons.

How is Heterotaxy Syndrome Treated?

Heterotaxy syndrome needs a comprehensive approach to treatment. Each child will have different needs. Treatment options are guided by the nature and severity of the condition.

Almost all children with right atrial isomerism will need a series of surgeries to repair the heart and the circulatory system. In this series, the Fontan procedure creates a single ventricle to pump blood throughout the body.  This replaces the heart’s two pumping chambers with one chamber.

Most children with left atrial isomerism have surgery and/or a cardiac catheterization to fix holes in the heart walls or other problems. Abnormal heart rhythm may be treated with pacemakers or defibrillators. In some mild cases, children with this condition do not need treatment other than regular check-ups with a pediatric heart doctor (cardiologist).

Both right and left atrial isomerism may also need medicines and other treatments to lower blood pressure and reduce stress on the heart muscle. Some treatments may include surgery for a malrotation of the intestines to prevent bowel obstruction or daily antibiotics for patients with a dysfunctional spleen to ward off infection.  

What are the Long-term Effects of Heterotaxy Syndrome?

The long-term outlook for children with heterotaxy syndrome depends on when the condition is diagnosed, and which organs are affected. While survival rates have increased, babies who have open heart surgeries are at higher risk for lung, liver and gastrointestinal (GI) diseases, as well as neurodevelopmental problems. They will often need a heart transplant later in life. Those diagnosed as adults tend to have fewer medical problems.

Children born with heterotaxy syndrome will need the lifelong care of a cardiologist and, most likely, several other specialists.