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Hypoplastic Left Heart Syndrome

  • Cynthia M. Johnson, MA
Publication Type:


Hypoplastic Left Heart Syndrome



Hypoplastic left heart syndrome (HLHS) is a rare heart problem. Structures on the left side of the heart, such as the aorta, aortic valve, left ventricle, and mitral valve, may be too small, missing, or not formed right. This reduces the amount of oxygen the body can use.

Heart Chambers and Valves.

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Blood Flow Through the Heart.

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HLHS is present at birth. It is caused by a genetic issue. It is not known why the heart does not form the right way.

Risk Factors

Things that may raise the risk of having a child with HLHS are:

  • Family members who were born with heart problems
  • Prior pregnancy with fetal heart problems or miscarriage


Within days after birth a baby may have:

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


The diagnosis may be suspected during an ultrasound before the child is born.

If the diagnosis was not made before birth, the doctor will ask about symptoms and health history. A physical exam will be done.

Pictures may be taken of the child's chest. This can be done with an echocardiogram. This can confirm the diagnosis.


Some of these issues are hard to treat. Some options are:

  • Medicines to help with blood flow
  • Supportive care, such as IV fluids, a feeding tube, or help with breathing
  • A series of surgeries to let the right ventricle do the work of two ventricles

Children with HLHS will need to regularly see a doctor who treats heart issues as they grow up.


HLHS cannot be prevented.





  • Feinstein, J.A., Benson, D.W., et al. Hypoplastic left heart syndrome: current considerations and expectations. J Am Coll Cardiol, 2012; 59 (1 Suppl): S1-S42. Correction can be found in J Am Coll Cardiol, 2012; 59(5): 544.
  • Hypoplastic left heart syndrome. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/hypoplastic-left-heart-syndrome.
  • Single ventricle defects. American Heart Association website. Available at: http://www.heart.org/en/health-topics/congenital-heart-defects/about-congenital-heart-defects/single-ventricle-defects.


  • Chelsea Skucek, MSN, BS, RNC-NIC
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.