Hypoplastic left heart syndrome (HLHS) is a rare heart defect. With this syndrome, structures on the left side of the heart, such as the aorta, aortic valve, left ventricle, and mitral valve, may be:

  • Too small
  • Absent
  • Poorly developed

Since the heart can’t work the right way, oxygen-rich blood flow to the body is lower. Your child will need medical care right away.

Heart Chambers and Valves
heart anatomy
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Blood Flow Through the Heart
Copyright © Nucleus Medical Media, Inc.


HLHS is present at birth. It is caused by a genetic defect. It is not known exactly why the heart does not develop normally.

Risk Factors

Factors that may raise your chance of having a child with HLHS are:

  • People in your family who have congenital heart defects
  • Prior pregnancy with fetal heart problems or miscarriage


Symptoms often appear within days after birth. Tell the doctor if your baby has:

  • Blue/gray skin color
  • Cool skin
  • Problems breathing
  • Fast heart beat
  • Sweaty, clammy skin
  • Poor feeding


You will be asked about your child's symptoms and health history. A physical exam will be done.

Pictures may be taken of your child's chest. This can be done with:


Talk with your doctor about the best plan for your child. Some defects are hard to treat. Your child may have:


Medicines are needed to keep blood flowing through the ductus arteriosus. The ductus arteriosus is a connection between the pulmonary artery and the aorta. It should close within a few days after birth. Keeping this passage open is a short term treatment. Other medicines may be used as well.


Surgery may be done to help the blood flow. This can be done through a reconstructive and shunting procedures. This is often done in stages:

  • After birth
  • 4-6 months of age
  • 2-4 years of age

Lifelong Monitoring

Your child will need to see a heart specialist regularly. Heart medicine will be needed throughout your child's life.


HLHS can’t be prevented.

Revision Information

  • Reviewer: Kari Kassir, MD
  • Review Date: 05/2018 -
  • Update Date: 06/29/2018 -