What is heterotaxy (isomerism)?
Heterotaxy, also called isomerism, is a rare condition that is usually diagnosed in utero. Heterotaxy results in a different arrangement of organs in the chest and abdomen. There are different forms of heterotaxy and approximately 80% involve heart conditions of varying types and severity. Heterotaxy happens with some of the most complex structural heart diseases. Isomerism often affects other organs, including:
- Stomach: position changes and increased feeding difficulties
- Intestines: abnormal arrangement, twisting of intestines or underdevelopment
- Spleen: no spleen or a small spleen and increased risk for infections
- Liver: abnormal communications between the liver and other blood vessels or liver in the wrong location
- Lungs: a genetic breathing condition called primary ciliary dyskinesia or other respiratory illnesses
- Heart Rhythm: too fast or slow heart rates
What is the life expectancy for heterotaxy?
The long-term outlook for children with heterotaxy depends largely on how severely it affects their organs — especially the heart. Children with more complex heart conditions may face greater medical challenges, but advances in surgery and medical care make it possible to repair many forms of congenital heart disease. With the right care, many children with heterotaxy can survive into adolescence and adulthood; however, all will need lifelong medical follow-up.
What causes isomerism?
Heterotaxy happens because of changes in a child’s genes. Sometimes these changes are passed down from one or both parents, and other times they happen randomly. In families with a history of heterotaxy, it may be possible to screen for heterotaxy before birth; however, most times, experts don’t detect heterotaxy until second trimester ultrasounds or even after birth.
Who gets heterotaxy?
Heterotaxy is rare and can affect anyone, regardless of race, ethnicity or gender. It usually develops early in pregnancy while the baby’s organs are forming. In some cases, it runs in families, but often it happens without any family history.
How rare is heterotaxy?
Heterotaxy affects about 1 in every 10,000 newborns. Some experts suspect isomerism could be more common than that because they also believe it is underdiagnosed.
How is heterotaxy diagnosed?
Prenatal ultrasound can identify babies with heterotaxy before birth due to abnormal organ arrangement or structural heart problems in the baby. Often, experts first notice isomerism during a routine second trimester ultrasound, when the organs in the chest or abdomen appear out of place or don’t formed as expected. If doctors see something unusual, they’ll usually refer the family to maternal fetal medicine (MFM) and pediatric cardiology specialists for more detailed evaluation
What can I expect from a Colorado Fetal Care Center visit for heterotaxy?
If you're referred to the Colorado Fetal Care Center, you'll likely get a call to schedule appointments with both an MFM specialist and a pediatric cardiologist. During your visit, your baby may have several types of imaging, including a detailed ultrasound, a fetal echocardiogram to evaluate the heart and possibly a fetal MRI. After the tests, a team of specialists will sit down with you to explain what they found, how your baby’s organs are working and what to expect after birth. Depending on your baby’s needs, you may also meet with additional experts like electrophysiologists (who focus on heart rhythms), cardiac surgeons, interventional cardiologists or pediatric surgeons. Together, the team will create a personalized plan for follow-up care and delivery to make sure everything is in place to support your baby after birth. Most babies with heterotaxy deliver at the Colorado Fetal Care Center, and many need heart surgery or a catheter-based procedure in their first few weeks of life.
After birth, we may recommend additional testing, including:
- Chest X-ray to look at the size and position of the heart and lungs
- Electrocardiogram (EKG) to check the heart rhythm
- Echocardiogram to evaluate heart structure and function
- Cardiac MRI or CT scan to provide more detailed pictures of the heart and blood vessels
- Cardiac catheterization to measure pressures in the heart and gather important information for surgical planning
- Abdominal or liver ultrasound to look at the liver and intestines
- Lung tests (such as a nasal ciliary swab and nasal nitric oxide measurements) to assess how the lungs clear mucus and function
- Spleen scan to identify if the spleen is present and working properly
- Genetic test to identify possible causes of heterotaxy
Treatment for heterotaxy
Many babies with heterotaxy will require surgery shortly after birth and delivery at a center capable of caring for high-risk pregnancies like our Colorado Fetal Care Center. Treatment can vary widely depending on how isomerism affects each child. Many babies will need heart surgery or a catheter-based procedure in the first few weeks of life, and some may require additional heart surgeries as they grow. Others may need surgery for problems in other organs, such as the intestines, especially if there’s a blockage. Some children with milder forms of heterotaxy may not need any surgery at all. No matter the severity, all children with heterotaxy will need regular, lifelong follow-up to monitor their heart and other organs. After reviewing all the test results, your child’s care team will work closely with you to create a personalized treatment plan that meets your child’s unique needs.
Why choose us for heterotaxy treatment?
Choosing where to get heterotaxy care for your baby is an important decision, and our team offers the experience and resources needed to support you and your family every step of the way. At our high-acuity center, you'll find a full team of pediatric specialists —including cardiologists, surgeons, pulmonologists, gastroenterologists, immunologists, and other experts — who care for children both before and after birth. We use advanced imaging technology, such as fetal echocardiography, MRI and postnatal cardiac imaging, to fully understand your baby’s condition and create a detailed, personalized care plan. Our team also works together to coordinate a carefully designed care plan for delivery and right after birth to support your baby during their critical early moments. This collaborative, highly specialized approach helps ensure that your child receives the best possible care from the very beginning.
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