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Hypoplastic left heart syndrome

In hypoplastic left heart syndrome, the left side of the heart — including the aorta, aortic valve, left ventricle and mitral valve — is underdeveloped. Blood returning from the lungs must flow through an opening in the wall between the atria, called an atrial septal defect (ASD) or patent foramen ovale (PFO). The right ventricle pumps the blood into the pulmonary artery, and blood reaches the aorta through a patent ductus arteriosus (PDA). The baby often seems normal at birth, but will need medical attention within a few days as the ductus closes.

This heart defect is usually fatal within the first days or months of life without treatment. It isn't correctable, but some babies can be treated with a series of operations or with a heart transplant.

​Typical Heart ​Heart with Hypoplastic Left Heart Syndrome


Babies with this syndrome have:
  • Poor color and mottled skin
  • Rapid and difficult breathing
  • Difficulty feeding


The diagnosis is made first after symptoms develop that are similar to other disorders in newborn babies, such as serious infections. There are also subtle features on the physical examination that suggest there is an underlying heart defect, but there may not be any abnormal heart murmurs. The diagnosis is confirmed with an echocardiogram. 

The specialists in Lurie Children's Heart Center diagnose and treat hypoplastic left heart syndrome. Learn more.


Until an operation is performed, the ductus is kept open by an intravenous (IV) medication known as prostaglandin. Heart transplantation is a treatment option, but donor organs for infants are rare. Therefore, surgery more commonly involves a series of operations.

  1. The first stage, called the Norwood procedure, allows the right ventricle to pump blood to the body. It consists of connecting the main pulmonary artery and tiny aorta together and enlarging any areas that are small. Because the main pulmonary artery is disconnected from the right and left pulmonary arteries, a BT shunt needs to be placed to supply blood flow to the pulmonary arteries. Also, the hole between the left and right atrium is enlarged so that blood returning from the lungs can get to the right atrium without obstruction. In the right atrium, blood returning from the lungs mixes with blood returning from the body (from the veins in the upper half of the body known as the superior vena cava, and the lower half of the body known as the inferior vena cava). The Norwood procedure should be performed soon after birth as the i.v. prostaglandin cannot be given indefinitely.
  2. The second stage is called a bi-directional Glenn, or hemi-Fontan operation, and consists of disconnecting the shunt to the pulmonary arteries and connecting the superior vena cava directly to the right pulmonary artery. With this, all the blood flow from the upper body no longer mixes with the blood returning from the lungs and the patient is less cyanotic.
  3. Later, a third stage is performed known as a Fontan operation. This consists of connecting the inferior vena cava to the right pulmonary artery as well. The end result is that all the blood from the upper and lower half of the body drains to the pulmonary arteries and goes to the lungs (the blue blood no longer mixes with the red blood). The way that these connections are performed may vary from patient to patient. The overall goals of the operation are to allow the right ventricle to pump only oxygenated blood to the body, and to prevent or reduce mixing of the red and blue blood. Although this operation does not lead to a normal heart, it can lead to a functional life.

Some doctors will recommend a heart transplant to treat this problem. Although it provides the infant with a heart that has normal structure, the infant will require lifelong medications to prevent rejection. Many other problems related to transplants can develop. You should discuss these with your doctor.

Treatment Risks

The risks of open-heart surgery always include bleeding, infection and the need for cardiopulmonary bypass. Special risks of the BT, Glenn and Fontan shunts include injury to the nerve that supplies the diaphragm resulting in paralysis of the diaphragm.

Additionally, the pulmonary artery may become narrowed in the area that the BT shunt, Glenn or Fontan shunts are sewn to the pulmonary artery. The aorta may have recurrent obstruction, and repair of the aorta carries the risk of injury to the nerve that controls one of the vocal cords.

Long-ter​m Effects

Left untreated, children with hypoplastic left heart syndrome usually die in early infancy. Long-term outlook is only beginning to be known, as this heart defect used to be fatal. Problems encountered over time include:
  • Rhythm abnormalities
  • Poor right heart function
  • Stroke
  • Swelling

Virtually every child with this condition will require heart medicines. Depending on the success of surgery, individuals may lead functional lives, though lifespan is probably shortened. Over time, the function of the right ventricle may worsen and heart transplantation may be required.

Children with hypoplastic left heart syndrome should have lifelong follow-up by a pediatric cardiologist for repeated checks of how their heart is working.

Related Specialties & Services

Read about the specialty areas and services that treat Hypoplastic left heart syndrome.