Pediatrics in Minnesota

Pediatric Hypoplastic Left Heart Syndrome (HLHS) Treatment at Mayo Clinic

Hypoplastic left heart syndrome is a severe abnormality of the left side of the heart, or the pumping chamber (left ventricle) and artery (aorta) that supply blood flow to the body. Typically, in HLHS, the left heart structures are very underdeveloped and cannot pump effectively enough to support life once a baby with HLHS is born.

Because the left-sided heart structures are underdeveloped, the right side of the heart does the work of pumping to both the lung and body circuit before a baby is born. The body receives blood through a communication called the Patent Ductus Arteriosus (PDA); it is when this PDA begins to close after birth that a baby with HLHS gets very sick, and if the PDA closes the baby will die. HLHS is usually fatal within a few days to a few weeks of birth, if left untreated.

Treatment Options

The baby with HLHS will require urgent medical evaluation once symptoms develop and will need transfer to a center with experienced pediatric cardiologists and cardiovascular surgeons. The abnormality can be fully diagnosed and evaluated with an echocardiogram (ultrasound of the heart). Once the diagnosis has been made, a medicine to keep the PDA open is given. This medicine is called Prostaglandin, and will help stabilize the baby while decisions are made regarding treatment. HLHS is not correctable with open-heart surgery, but two primary surgical options exist to treat babies with HLHS: the Norwood operation or heart transplantation.

Norwood Procedure
The first stage Norwood operation was developed to keep the right ventricle pumping to the body to support the baby's circulation, and would need to be done soon after diagnosis. In this surgery, the small aorta is "made larger" with a patch from a donor lung artery (homograft) and is connected to the right ventricle via the native lung artery. The lungs receive blood flow from a "shunt" that is made between the new aorta and the lung arteries. A baby will be blue, or cyanotic, after this first-stage surgery.

Typically, a baby who has had the Norwood procedure will have two more palliative (non-corrective) surgeries by age 3 years; a bidirectional Glenn shunt at 4 to 6 months of age, and completion of the modified Fontan procedure at approximately 2 years of age. Completion of these stages allows separation of the blue blood from the red blood. Long-term follow-up is needed to monitor the function of the right ventricle pumping to the body's circulation. Most patients will take medicine all of their lives.

Heart Transplantation
Heart transplantation involves replacement of the baby's heart with a donor heart that is normal in structure. This surgery is dependent on the availability of an infant heart donor. Long-term complications may include rejection of the heart, causing it to fail, development of infection, coronary artery problems, and complications from the medicines to prevent rejection. All patients who have had transplants are at risk for rejection of the heart and need to take medicine all of their lives.