Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome (HLHS) is a rare congenital heart defect that occurs when the left side of your baby’s heart does not develop correctly in utero.

Remarkable Care for Kids

  • Pediatric cardiology expertise: Experts in the Rush Pediatric Congenital Heart Disease Program provide advanced medical and surgical repair for hypoplastic left heart syndrome (HLHS), including a hybrid procedure — which involves minimal surgery and does not require using the heart-lung bypass machine.
  • Multidisciplinary prenatal care: The Rush Fetal and Neonatal Medicine Center and the Fetal Cardiac Program at Rush offer prenatal testing and diagnosis for HLHS during your pregnancy. These specialized teams include experts in maternal-fetal medicine, fetal cardiology and pediatric cardiology. They will work with you and each other to provide support, evaluation and treatment during your pregnancy and after your child is born.
  • Excellence in neonatal intensive care: Babies with HLHS need neonatal intensive care to help them with breathing and circulation issues at birth. The Renée Schine Crown Neonatal Intensive Care Unit (NICU) at Rush is located next to labor and delivery, allowing neonatal intensive care specialists to care for your child seconds after delivery.
  • Care close to home: Pediatric cardiologists at Rush University Children’s Hospital can see patients at a number of convenient locations. They are available at our three hospital locations — Rush University Medical Center in Chicago, Rush Oak Park Hospital in Oak Park and Rush Copley Medical Center in Aurora — and also at satellite locations throughout the city and the suburbs, including Joliet, Hoffman Estates, Tinley Park and Crown Point.

What is hypoplastic left heart syndrome?

In a healthy heart, the left ventricle pumps oxygenated blood to the rest of the body; however, for children with hypoplastic left heart syndrome (HLHS), the left ventricle does not function properly. This inhibits blood from flowing normally through the heart.

All babies born with HLHS need open-heart reconstructive surgeries to redirect blood through their bodies.

This is a serious condition that requires immediate medical care; it can be fatal if left untreated.

Symptoms of hypoplastic left heart syndrome

Prenatal ultrasounds and fetal echocardiograms, which take images of your baby’s heart before birth, can easily detect hypoplastic left heart syndrome during pregnancy.

When the defect goes undetected, however, babies with this disorder are typically very sick at birth or shortly after they are born. Some symptoms of hypoplastic left heart syndrome include the following:

  • Bluish skin color
  • Problems breathing
  • Pounding heartbeat
  • Weak pulse
  • Problems feeding

If your baby has any of these symptoms, contact your child’s doctor immediately and visit the nearest emergency room or call 911.

There is no known cause for HLHS; however, if one of your children has it, you have a slightly higher risk for having another baby with a congenital heart problem in a future pregnancy.

Care for hypoplastic left heart syndrome at Rush


If your prenatal ultrasound shows that your baby has a possible heart defect, your OB-GYN might refer you to a fetal cardiologist for a fetal echocardiogram to determine if your child has hypoplastic left heart syndrome or another heart condition.


After they are born, babies with hypoplastic left heart syndrome will need multiple reconstructive open-heart surgeries. These surgeries will redirect blood through the body to compensate for the defective left ventricle.

The surgeries include the following:

  • Norwood procedure: Performed within the first few days of your baby’s life. The procedure allows your baby’s right ventricle (the healthy side of the heart) to pump blood to the lungs and rest of the body.
  • Bi-directional Glenn Shunt: Performed when your baby is 4 to 6 months old. The procedure relieves the right ventricle from working too hard by allowing some of the blood to go to the lungs without passing through the right side of the heart.
  • Fontan procedure: Performed when your baby is between 18 months and 3 years old. This procedure changes the flow of blood to the lungs without passing through the right ventricle.
  • Hybrid procedure: Cardiologists and cardiac surgeons perform this procedure together and can use it in place of the Norwood procedure. This procedure involves minimal surgery and does not require using the heart-lung bypass machine. Surgeons and cardiologists place a stent in one of the heart vessels and place a band across the pulmonary arteries to limit the amount of blood that flows to the lungs.

Additional treatments

Your child may also need the following treatments:

  • Heart transplant: Your baby might need a heart transplant if they do not respond well to reconstructive surgery or if surgery is not an option.
  • Additional surgeries: As your child grows into adolescence, they may need additional cardiovascular surgeries to control arrhythmias or other heart-related problems associated with HLHS.
  • Follow-up care: Your child will need lifelong care and follow-up with a cardiologist who specializes in congenital heart defects. People born with heart defects may face unique challenges when they reach adulthood — including the need for additional surgery and an increased risk of sudden cardiac death.