Hypoplastic left heart syndrome is a rare but complex congenital heart defect. In this condition the left side of the heart is critically underdeveloped.
In hypoplastic left heart syndrome, the left side of the heart cannot effectively pump blood to the body so the right side of the heart pumps blood both to the lungs and the rest of the body.
Treatment for hypoplastic left heart syndrome involves medications to prevent closure of the connection (ducts arteriosus) between the right and left sides and surgery or heart transplant.
Symptoms of hypoplastic left heart syndrome in babies include:
- Grayish-blue skin color (cyanosis)
- Rapid, difficult breathing
- Poor feeding
- Cold hands and feet
- Unusually drowsy or inactive
In a baby with hypoplastic left heart syndrome, if the natural connections between the left and right sides of the heart are allowed to close, the baby may go into shock and die. Symptoms of shock include:
- Cool, clammy skin (pale or gray)
- A weak and rapid pulse
- Abnormal breathing (slow and shallow or rapid)
- Dilated pupils
- Lackluster eyes that seem to stare
Hypoplastic left heart syndrome develops during fetal growth while the baby’s heart is developing. However, the exact cause is unknown.
In hypoplastic left heart syndrome, the left side of the heart cannot supply blood to the body properly because the left ventricle is too small or it may not exist. Moreover, the valves on the left side of the heart (aortic and mitral valve) do not function properly and the main artery leaving the heart (aorta) is abnormally small.
During the first several days of life, the right side of the heart can pump blood both to the lungs and to the rest of the body through a natural opening between the upper chambers of the heart or through a blood vessel connecting the pulmonary artery to the aorta. However, if these openings close, which normally occurs after the first several days, the right side cannot pump blood to the body.
A family history of hypoplastic left heart syndrome increases the risk of new family members developing the condition. Having a child with hypoplastic left heart syndrome increases the risk of having another baby with the same condition.
Hypoplastic left heart syndrome is fatal without surgery. Although, many babies survive with treatment most develop complications later on. Complications may include:
- Tiring easily during sports or exercises
- Heart rhythm abnormalities (arrhythmias)
- Fluid buildup in the lungs, abdomen, legs and feet (edema)
- Formation of blood clots that may lead to a pulmonary embolism or stroke
- Developmental problems related to the brain and nervous system
- Need for additional heart surgery or transplant
Treatment for hypoplastic left heart syndrome includes a three-step surgical procedure or a heart transplant.
Prior to surgery
- Medications to help dilate the blood vessels and keep the ductus arteriosus open
- Breathing assistance to ensure proper oxygen delivery
- Intravenous fluids
- Atrial septostomy to create an opening between the heart’s upper chambers (atria) if the foramen ovale closes
Surgery to correct hypoplastic left heart syndrome includes a three-step procedure that aims to create normal blood flow in and out of the heart and allow the body to receive oxygen-rich blood.
Another surgical option is a heart transplant, especially when the defects are complex.
Follow up care
After heart surgery or transplant, the baby will require lifelong follow up care, which includes regular monitoring as well as medications to regulate heart function.