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Genetic and Rare Diseases Information Center (GARD)

Hypoplastic left heart syndrome

Other Names for this Disease
  • HLHS
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Your Question

My best friend's baby has hypoplastic left heart syndrome and she been told that it's not common here in Australia. The doctors don't know a lot about it and her baby has only days to live. How common is it? What is the prognosis?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is hypoplastic left heart syndrome (HLHS)?

Hypoplastic left heart syndrome (HLHS) is a problem with the heart’s structure that is present at birth (congenital). It occurs when parts of the left side of the heart (mitral valve, left ventricle, aortic valve, and aorta) do not develop completely.[1] The underdeveloped left side of the heart is unable to provide enough blood flow to the body, which decreases the oxygen-rich blood supply. Babies with HLHS might look normal at birth, but will develop symptoms of HLHS within a few days. These symptoms might include: poor feeding, problems breathing, pounding heart, weak pulse, and ashen or bluish skin color. The cause of HLHs is presently unknown.[2]
Last updated: 7/21/2011

What are the signs and symptoms of hypoplastic left heart syndrome (HLHS)?

Normally, oxygen-poor blood is pumped through the right side of the heart to the lungs, where it gains oxygen and returns to the left side of the heart. The oxygen-rich blood is then pumped from the left side of the heart to the rest of the body. At birth, all babies also have two connections, or shunts, between the two sides of the heart; however, within a few days of birth these connections close. In those with HLHS, the underdeveloped left side of the heart is unable to provide enough blood flow to the body. The normal shunts present at birth help to direct blood to the body; when these connections close the oxygen-rich blood supply decreases.[2]

At first, a newborn with HLHS may appear normal. Symptoms usually occur in the first few hours of life, although it may take up to a few days to develop symptoms. These symptoms may include:[1]

  • Bluish (cyanosis) or poor skin color
  • Cold hands and feet (extremities)
  • Lethargy
  • Poor pulse
  • Poor suckling and feeding
  • Pounding heart
  • Rapid breathing
  • Shortness of breath

In healthy newborns, bluish color in the hands and feet is a response to cold (this reaction is called peripheral cyanosis). However, a bluish color in the chest or abdomen, lips, and tongue is abnormal (called central cyanosis). It is a sign that there is not enough oxygen in the blood. Central cyanosis often increases with crying.[1]
Last updated: 7/21/2011

How common is hypoplastic left heart syndrome (HLHS)?

The Centers for Disease Control and Prevention (CDC) estimates that each year about 975 babies in the United States are born with hypoplastic left heart syndrome (HLHS). In other words, each year about 2 out of every 10,000 babies born will be born with HLHS.[2] Internationally, the frequency is similar to that in the United States.[3]
Last updated: 7/21/2011

How might hypoplastic left heart syndrome (HLHS) be treated?

Once the diagnosis of HLHS is made, the baby will be admitted to the neonatal intensive care unit. A breathing machine (ventilator) may be needed to help the baby breathe. A medicine called prostaglandin E1 is used to keep blood circulating to the body by keeping the ductus arteriosus open. These measures do not solve the problem and ultimately, the baby will require surgery. The first surgery, called the Norwood operation, occurs within the baby's first few days of life. Stage I of the Norwood procedure consists of building a new aorta by:[1]
  • Using the pulmonary valve and artery
  • Connecting the hypoplastic old aorta and coronary arteries to the new aorta
  • Removing the wall between the atria (atrial septum)
  • Making an artificial connection from either the right ventricle or a body-wide artery to the pulmonary artery to maintain blood flow to the lungs (called a shunt)

Afterwards, the baby usually goes home. The child will need to take daily medicines and be closely followed by a pediatric cardiologist, who will determine when the second stage of surgery should be done. Stage II of the operation is called the Glenn shunt or hemi-Fontan procedure. This procedure connects the major vein carrying blue blood from the top half of the body (the superior vena cava) directly to blood vessels to the lungs (pulmonary arteries) to get oxygen. The surgery is usually done when the child is 4 to 6 months of age. During stages I and II, the child may still appear somewhat blue (cyanotic).[1]

Stage III, the final step, is called the Fontan procedure. The rest of the veins that carry blue blood from the body (the inferior vena cava) are connected directly to the blood vessels to the lungs. The right ventricle now serves only as the pumping chamber for the body (no longer the lungs and the body). This surgery is usually performed when the baby is 18 months - 3 years old. After this final step, the baby is no longer blue. Some patients may need more surgeries in their 20s or 30s if they develop hard to control arrhythmias or other complications of the Fontan procedure.[1]

In some hospitals, heart transplantation is considered a better choice than the three-step surgery process. However, there are few donated hearts available for small infants.[1]
Last updated: 7/21/2011

What is the prognosis of hypoplastic left heart syndrome (HLHS)?

If left untreated, hypoplastic left heart syndrome is fatal. Survival rates for the staged repair continue to rise as surgical techniques and postoperative management improve. Survival after the first stage is more than 75%. Survival after the second and third surgeries is nearly 90-95%. The size and function of the right ventricle are important in determining the child's outcome after surgery.[1][3]
Last updated: 7/21/2011

Other Names for this Disease
  • HLHS
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.