Hypoplastic Left Heart Syndrome (HLHS)

Hypoplastic left heart syndrome must be treated soon after a baby is born, otherwise survival is not likely. Early detection of this condition ensures a baby’s greatest chance for living. Sometimes congenital disabilities or other abnormalities can be identified during routine prenatal testing. It is essential to keep all your prenatal examination appointments.

Treatment before birth – fetal cardiac intervention

Prenatal testing can detect congenital disabilities while a baby is still in the mother’s womb. Initially, an ultrasound may be used to create images of internal organs. The findings of the ultrasound can expose possible problems relating to the normal development of the baby’s heart. Hypoplastic left heart syndrome can be revealed using a fetal echocardiogram.

Some babies can receive interventional care for hypoplastic left heart syndrome while in the womb. The most experienced, skillful pediatric cardiovascular surgeons perform a procedure called a balloon valvuloplasty, where a tiny needle equipped with a balloon catheter is used to open the affected heart valve or obstruction. In addition, birth defects that are discovered prior to birth allow doctors to be prepared with equipment necessary for an infant’s emergency medical care.

Surgeries and medical treatment after birth

Not all babies are candidates for fetal intervention treatments. Therefore, children born with hypoplastic left heart syndrome require surgery within the first few days or weeks following their birth. There are a series of three operations used to treat HLHS.

• Stage 1: Norwood procedure (newborn). This intricate surgery is performed by the most experienced pediatric cardiothoracic surgeons. An incision is made in the chest of the baby, exposing the heart, lungs, pulmonary artery, and aorta artery. Then the baby is placed on the heart-lung machine to provide oxygen and blood flow to the body during the operation. Other medical specialists (perfusionists) are present to monitor the baby’s brain function and oxygenation to the other organs. Once the procedure (bypass) is performed, the heart is placed back into the baby’s body. This complex operation has three main steps:
  • Step 1: Aorta reconstruction. This is the most difficult part of the operation. The bottom side of the pulmonary artery, which connects the right ventricle to the lungs, is then attached to the aorta. This creates a larger aorta that goes from the right ventricle to the body.
  • Step 2: Pulmonary blood flow source. Since the pulmonary artery has been redirected from the right ventricle to the body, a shunt is used to create a source of blood flow to the lungs. Shunts typically used in this procedure are:
    • Blaylock-Taussig-Thomas shunt. This moves blood to and from the aorta to the lungs.
    • Sano shunt. This moves blood from the right ventricle to the pulmonary artery. The blood is directed from the pulmonary artery into the lungs.
    • Removal of the atrial septum. The wall between the right and left side of the atrial septum (atrium) is completely removed. The baby is then carefully removed from the bypass machine and given medication to help the heart pump harder. An echocardiogram will be done to ensure the operation was successful.
• Stage 1 alternative: The hybrid approach. This entails a combination of bilateral pulmonary bands or internal percutaneously placed flow occluders, along with ductal stenting or ongoing prostaglandin therapy for delayed Norwood procedure. This approach is used for high-risk cases such as premature and small birth weight babies.
• Stage 2: Bidirectional Glenn procedure (superior cavopulmonary connection). The second stage in the series of operations takes place between the ages of four to six months. All the previous shunts to the lungs are removed. Blood flowing from the head and arms is redirected and connected to the lungs. Most children thrive well after this operation.
• Stage 3: Fontan procedure. The third stage of the series of operations takes place between the ages of two to three years. The blood from the lower part of the body (inferior vena cava) is redirected, allowing it to passively flow straight to the lungs. This redirection allows blood to flow from the heart to the body and then returning to the lungs directly to receive oxygen. This rerouting is most like the heart’s normal circulation. There are various modifications to the Fontan procedure.
• Heart transplant. This course of action for children with hypoplastic left heart syndrome is considered an option, even after they have gone through the three previous procedures. There is limited availability of a donor heart suitable for the size of an infant. Children who undergo a heart transplant must continue with long-term and complex care that is required after such an operation.

With all the medical progress and treatments that continue to arise, the survival rate for children with HLHS has improved significantly. Most children reach adulthood but will require additional catheter or surgical procedures, such as a pacemaker for abnormal heartbeats, in the future. Others may eventually require a heart transplant.

Long term care and continued visits to the cardiologist are essential for the overall health of the child. While some physical activities or contact sports may be curtailed, however, children can live happier lives with their updated heart.