Heterotaxy Syndrome (Isomerism)

Heterotaxy syndrome, also known as isomerism, is a rare disorder that affects where organs are located in the body. During pregnancy, a baby’s heart may develop in the right side of the chest instead of the left. Other organs like the lungs, stomach, liver and spleen may form in the wrong place, not form properly, or be missing altogether. In some cases, multiple spleens form but none function correctly. Sometimes this condition affects only one or two organs; sometimes it affects many. It can lead to serious or life-threatening complications.

No two cases of heterotaxy syndrome are exactly alike, but most involve the heart – in particular, changes in how the heart’s upper chambers (atria) develop. There are two main categories.

  • Right atrial isomerism: Instead of having a left atria and a right atria, the heart has two right atria. Often, this condition also involves problems with the heart’s valves, holes in the heart’s dividing walls, or other heart defects.
  • Left atrial isomerism: Instead of having a left atria and a right atria, the heart has two left atria. This condition may also include valve problems, holes in the dividing walls, and problems with the heart’s electrical system. 

Often, patients with heterotaxy syndrome have other heart defects, too, including problems with the heart’s ventricles, connections, veins and muscle.

These heart problems can range from mild to very serious and complex.

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What Are the Signs and Symptoms of Heterotaxy Syndrome (Isomerism)?

Heterotaxy syndrome is often diagnosed before birth through fetal echocardiography, allowing Connecticut Children’s to put an action plan in place for a family and baby right from delivery. Or it’s detected very soon after birth.

The most common signs of heterotaxy syndrome are similar to many other heart problems.

  • Bluish or grayish lips, skin and lips
  • Fast breathing
  • Trouble feeding
  • Poor weight gain
  • Low energy and activity

Sometimes in less severe cases, children with this condition only have mild symptoms, or no symptoms at all. They might not even be diagnosed with heterotaxy syndrome until later in life.
 

What Causes Heterotaxy Syndrome (Isomerism)?

This condition occurs before birth, when a baby’s organs don’t develop properly during pregnancy.

Sometimes, heterotaxy syndrome is passed down directly from a parent’s genes. Other times, something happens during pregnancy, like contact with a certain chemical, that suddenly changes the baby’s genes. Sometimes, there’s no known cause.

How is Heterotaxy Syndrome (Isomerism) Treated?

Heterotaxy syndrome affects each patient differently, so treatment depends on which organs are involved and how serious each problem is. (For example, many patients only have one fully working ventricle in their heart instead of two, which affects their surgical options.)

Connecticut Children’s Heart Center uses echocardiography and cardiac magnetic resonance imaging (MRI) to get a detailed understanding of the heart, and plan treatment that’s unique for each patient. Because heterotaxy syndrome can involve so many parts of the body, a patient’s care team also often includes experts in urology, nephrology and many more of our 30-plus pediatric specialties.

Here are some of the possible treatments for heterotaxy syndrome.

  • Medication to help the heart or kidneys work better and protect against infections
  • Cardiac catheterization (a minimally invasive procedure using a long, thin tube) to correct some heart problems
  • Pacemaker: Device placed in the chest to control the heart rhythm
  • Repair holes in the heart’s wall
  • If only a single working ventricle, staged reconstruction known as “single ventricle palliation”: A series of open-heart surgeries to rebuild the heart and redirect how blood flows through it
    • Norwood procedure: Allows the right ventricle to pump blood to the body
    • Glenn procedure: Connects a large vein to the pulmonary artery, allowing blood to flow directly to the lungs
    • Fontan procedure: Directs blood from the lower half of the body directly into the lungs to receive oxygen
  • Other procedures to reconstruct the heart
  • Reconstruct other organs

Patients with heterotaxy syndrome need lifelong follow-up care by congenital heart experts. Connecticut Children’s Heart Center specializes in this kind of care. We understand the unique anatomy of individuals who have had surgery or a procedure to correct this condition. We also provide advanced heart imaging close to home, and a seamless transition to congenital heart care for adults.