Heterotaxy syndrome is a rare birth defect involving the heart and other internal organs. “Hetero” means different and” taxy” mean arrangement – so the organs have a different arrangement. It is seen in boys and girls equally and can occur in all ethnic groups. Four babies in one million are born with this problem.
In heterotaxy syndrome, paired organs like the lungs or kidney are often mirror images of each other instead of having the features of right and left that normally occur.
There are different forms of heterotaxy syndrome with long medical names like right atrial isomerism and left atrial isomerism. “Isomerism” means mirroring. These words come from a pouch found on the upper chamber of the heart (the atria) called the atrial appendage. Each side has its own special shape but with heterotaxy, each side can look identical whether on the right or the left. Almost all (80 percent) involve heart defects of varying types and severity. The stomach, intestines, liver and lungs may be in abnormal places.
Other issues that may be associated with heterotaxy syndrome:
- Intestines that have malrotation, where the bowel loops are lined up incorrectly. This can cause the bowel to twist on itself. Many children with malrotation need abdominal surgery to fix or prevent obstruction.
- A serious liver condition called biliary atresia. This is a failure of the bile ducts to form that drain the liver. This needs surgical correction or transplantation.
- In some children the spleen may not work correctly or be completely missing (asplenia). Sometimes the spleen is in many pieces (polysplenia). Tests will need to be done to see if the spleen functions with polysplenia. The spleen helps the body fight infection so this is very important, particularly after surgery. Some children will need to take daily antibiotics and receive extra vaccinations to protect them from infection.
- In some children the heart is in the right side of the chest instead of the left chest (dextrocardia).
- Some children have abnormal lung lobes. Usually there are three lobes on the right and two on the left. This can be reversed or a child can have three lobes on both sides or two lobes on both sides.
- The heart has its own electrical system that tells it to beat and sends the electricity throughout the heart. With heterotaxy syndrome there is a risk of irregular electrical signals, possibly requiring a pacemaker.
Because heterotaxy syndrome involves many body organs and the heart problems can be very severe, the prognosis is poor. With the asplenia type, one-year mortality can be as high as 85 percent. In the polyspenia type, the one year mortality can be as high as 50 percent. This is partly due to the heart issues, but also because of the ongoing risk of infection.