Before birth

It's possible for a baby to be diagnosed with hypoplastic left heart syndrome in the womb. A routine ultrasound exam during the second trimester of pregnancy might show the condition.

After birth

A baby with grayish-blue lips or trouble breathing at birth might have a heart defect, such as hypoplastic left heart syndrome. Other possible symptoms of a heart problem are a heart murmur, which is a sound caused by rushing blood flow that can be heard through a stethoscope.

An echocardiogram can diagnose hypoplastic left heart syndrome. This test uses sound waves that bounce off the baby's heart to produce moving images that show on a video screen.

For babies with hypoplastic left heart syndrome, the echocardiogram shows a small left ventricle and aorta. The echocardiogram might also show issues with heart valves.

Because this test can track blood flow, it shows blood moving from the right ventricle into the aorta. And an echocardiogram can identify other heart conditions, such as an atrial septal defect.


Hypoplastic left heart syndrome is treated through several surgical procedures or a heart transplant. Your child's health care provider will discuss treatment options with you.

If the diagnosis is made before birth, care providers usually recommend delivery at a hospital with a cardiac surgery center.

Options to help manage a baby's condition before surgery or transplant include:

  • Medication. The medication alprostadil (Prostin VR Pediatric) helps widen the blood vessels and keeps the ductus arteriosus open.
  • Breathing assistance. Babies who have trouble breathing might need help from a breathing machine (ventilator).
  • Intravenous fluids. A baby might receive fluids through a tube inserted into a vein.
  • Feeding tube. Babies who have trouble feeding or who tire while feeding can be fed through a feeding tube.
  • Atrial septostomy. This procedure creates or enlarges the opening between the heart's upper chambers to allow more blood flow from the right atrium to the left atrium. This is done if the foramen ovale closes or is too small. Babies who already have an opening (atrial septal defect) might not need this procedure.

Surgeries and other procedures

Children with hypoplastic left heart syndrome will likely need several surgeries. Surgeons perform these procedures to create separate pathways to get oxygen-rich blood to the body and oxygen-poor blood to the lungs. The procedures are done in three stages.

  • Norwood procedure. This surgery is usually done within the first two weeks of life. There are several ways to do this procedure.

    Surgeons reconstruct the aorta and connect it to the heart's lower right chamber. Surgeons insert a tube (shunt) that connects the aorta to the arteries leading to the lungs (pulmonary arteries), or they place a shunt that connects the right ventricle to the pulmonary arteries. This allows the right ventricle to pump blood to both the lungs and the body.

    In some cases, a mixed procedure is done. Surgeons implant a stent in the ductus arteriosus to maintain the opening between the pulmonary artery and the aorta. Bands placed around the pulmonary arteries reduce blood flow to the lungs and create an opening between the atria of the heart.

    After the Norwood procedure, a baby's skin will still be discolored because oxygen-rich and oxygen-poor blood continue to mix within the heart. Once a baby successfully passes through this stage of treatment, the odds of survival can increase.

  • Bidirectional Glenn procedure. This procedure is generally the second surgery. It's done when a child is between 3 and 6 months of age. It involves removing the first shunt and connecting one of the large veins that returns blood to the heart (the superior vena cava) to the pulmonary artery. If surgeons previously performed a hybrid procedure, they'll follow additional steps during this procedure.

    This procedure reduces the work of the right ventricle by allowing it to pump blood mainly to the aorta. It also allows most of the oxygen-poor blood returning from the body to flow directly into the lungs without a pump.

    After this procedure, all the blood returning from the upper body is sent to the lungs, so blood with more oxygen is pumped to the aorta to supply organs and tissues throughout the body.

  • Fontan procedure. This surgery is usually done when a child is between 18 months and 4 years of age. The surgeon creates a path for the oxygen-poor blood in one of the blood vessels that returns blood to the heart (the inferior vena cava) to flow directly into the pulmonary arteries. The pulmonary arteries then send the blood into the lungs.

    The Fontan procedure allows the rest of the oxygen-poor blood returning from the body to flow to the lungs. After this procedure, there's little mixing of oxygen-rich and oxygen-poor blood in the heart. So the skin will no longer look discolored.

  • Heart transplant. Another surgical option is a heart transplant. However, the number of hearts for transplant is limited, so this option is not used as often. Children who have heart transplants need medications throughout life to prevent rejection of the donor heart.

Follow-up care

After surgery or a transplant, a baby needs lifelong care with a cardiologist trained in congenital heart diseases. Some medications might be needed for heart function. Various complications can occur over time and might require further treatment or other medications.

The child's cardiologist will decide whether the child needs to take preventive antibiotics before certain dental or other procedures to prevent infections. Some children might also need to limit physical activity.

Follow-up care for adults

Adult care requires a cardiologist trained in congenital heart disease in adults. Recent advances in surgical care have allowed children with hypoplastic left heart syndrome to grow into adulthood. So it's not yet clear what challenges an adult with the condition might face. Adults need regular, lifelong follow-up care to watch for changes in the condition.

People considering pregnancy should discuss pregnancy risks and birth control options with their health care providers. Having this condition increases the risk of cardiovascular problems during pregnancy, the risk of miscarriage and the risk of having a baby with congenital heart disease.

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this condition.

Coping and support

It can be challenging to live with hypoplastic left heart syndrome or to care for a baby with the condition. Here are some strategies that might help:

  • Seek support. Ask family members and friends for help. Caregivers need breaks. Talk with your child's cardiologist about support groups and other types of assistance.

    If you're a teen or an adult with hypoplastic left heart syndrome, ask your health care provider if there are support groups for adults with congenital heart conditions. It can be helpful to talk to other people who share your challenges.

  • Keep health records. Write down your or your baby's diagnosis, medications, surgery and other procedures and the dates they were performed. Include the name and phone number of the cardiologist, emergency contact numbers for health care providers and hospitals, and other important information. Include a copy of the report from the surgeon in the records.

    This information will help you keep track of the care received. It will be useful for care providers who don't know the complex health history. This information is also helpful as your child moves from pediatric care to adult cardiology care.

  • Talk about your concerns. Talk with your child's cardiologist about which activities are best for your child. If some are off-limits, encourage your child in other pursuits rather than focusing on what can't be done.

    If other issues about your child's health concern you, discuss them with your child's cardiologist too. If you are an adult with hypoplastic left heart syndrome, ask your care provider about activities you can do. Talk about your concerns.

Hypoplastic left heart syndrome care at Mayo Clinic

Aug. 12, 2022

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  1. Rathod RH. Hypoplastic left heart syndrome: Anatomy, clinical features, and diagnosis. https://www.uptodate.com/contents/search. Accessed June 9, 2022.
  2. Ani T. Allscripts EPSi. Mayo Clinic. June 1, 2022.
  3. Libby P, et al., eds. Congenital heart disease in the adolescent and adult. In: Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Elsevier; 2022. https://www.clinicalkey.com. Accessed June 9, 2022.
  4. Facts about hypoplastic left heart syndrome. Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/heartdefects/HLHS.html. Accessed June 9, 2022.
  5. Single ventricle defects. American Heart Association. https://www.heart.org/en/health-topics/congenital-heart-defects/about-congenital-heart-defects/single-ventricle-defects. Accessed June 9, 2022.
  6. Rathod RH. Hypoplastic left heart syndrome: Management and outcome. https://www.uptodate.com/contents/search. Accessed June 9, 2022.
  7. Waltzman M. Initial evaluation of shock in children. https://www.uptodate.com/contents/search. Accessed June 9, 2022.
  8. Wojtowicz A, et al. Hypoplastic left heart syndrome: From the prenatal to the postnatal period. Ginekologia Polska. 2021; doi:10.5603/GP.a2020.0160.
  9. What are congenital heart defects? National Heart, Lung, and Blood Institute. https://www.nhlbi.nih.gov/health-topics/congenital-heart-defects. Accessed June 9, 2022.
  10. van Hagen IM, et al. Pregnancy in congenital heart disease: Risk prediction and counseling. Heart. 2020; doi:10.1136/heartjnl-2019-314702.