Understanding Hypoplastic Left Heart Syndrome (HLHS) in Babies

Hypoplastic left heart syndrome (HLHS) is a rare congenital heart defect that affects about 1,000 babies in the United States each year. In this condition, the left side of a baby's heart doesn't develop properly during pregnancy, leading to complications after birth. This article will help you understand the causes, symptoms, diagnosis, treatment options, and long-term outlook for babies with HLHS.

What is Hypoplastic Left Heart Syndrome?

In a healthy heart, the right side pumps blood to the lungs to receive oxygen, while the left side pumps the oxygen-rich blood to the rest of the body. In babies with HLHS, the left side of the heart is underdeveloped, making it unable to effectively pump blood to the body. This can be due to a smaller or absent lower left chamber, malfunctioning valves on the left side, or a narrowed main artery leaving the heart.

Causes of HLHS

The exact cause of HLHS is unknown, but it appears to run in families, suggesting a genetic component. Some experts believe that certain environmental factors during pregnancy, such as smoking, alcohol consumption, or lack of folic acid in the mother's diet, may increase the risk of a baby developing HLHS.

Symptoms and Diagnosis

Symptoms of HLHS may not be apparent until a few days after birth when the baby's heart can no longer adjust to the defect. Common signs include:

• Sleepiness or lack of movement

• Cold hands and feet

• Fast breathing or difficulty breathing

• Gray or blue skin

• Poor feeding

Doctors may detect a heart murmur when listening to the baby's heartbeat. If HLHS is suspected, an echocardiogram will be performed to visualize the heart's chambers and blood flow.

Treatment Options

Prompt diagnosis and treatment are crucial for babies with HLHS to ensure adequate blood flow to the organs. Initial treatments may include:

• Medication to keep the ductus arteriosus open and support heart function

• IV fluids or feeding tubes to provide nutrition

• Ventilator support to ensure adequate oxygen levels

• Atrial septostomy to create an opening between the heart's upper chambers

Babies with HLHS typically undergo a series of surgeries to repair the heart, starting with the Norwood procedure soon after birth, followed by the Glenn procedure at a few months old, and the Fontan procedure at 3-4 years old. In some cases, a heart transplant may be recommended.

Long-term Outlook

Children with HLHS require lifelong care from a cardiologist specializing in congenital heart defects. They may need additional surgeries and face a higher risk of other heart problems, such as irregular heart rhythms and blood clots. Physical weakness and developmental issues are also possible, and these children may require extra support at home and school.

While HLHS is a serious condition, advances in medical care have greatly improved the outlook for affected babies. With proper treatment and ongoing care, many children with HLHS can lead fulfilling lives.

For more information on hypoplastic left heart syndrome, visit:

• Centers for Disease Control and Prevention (CDC) - HLHS

• National Heart, Lung, and Blood Institute (NHLBI) - HLHS

• Children's Hospital of Philadelphia (CHOP) - HLHS