Hypoplastic Left Heart Syndrome (HLHS)

What is Hypoplastic Left Heart Syndrome (HLHS)?

Hypoplastic Left Heart Syndrome (HLHS) is a rare congenital heart defect in which the left side of the heart is underdeveloped. The left side of the heart is made up of the left ventricle, left atrium, aortic valve, and aorta and its function is to pump oxygen-rich blood out of the heart to the body. In HLHS, these parts of the heart are underdeveloped so that the heart is unable to pump enough blood to the body.

When a baby has HLHS, their right ventricle pumps the blood it receives from both the right atrium (from the lungs) and left atrium (from the body). There is a narrowing or "stenosis" of the aortic valve, and the resulting pooling of blood in the left atrium often leads to elevated pressure in the left side of the heart, resulting in heart failure.

HLHS is a serious condition that requires medical attention and treatment. Without treatment, the heart will eventually fail. Treatment of HLHS usually involves a series of corrective surgeries and/or a heart transplant.

Signs and Symptoms of HLHS

The signs and symptoms of HLHS depend on the severity of the condition. Common signs and symptoms include:

  • Rapid breathing
  • Bluish skin color (cyanosis)
  • Poor weight gain
  • Rapid heart rate
  • Difficulty feeding
  • Lethargy or fatigue
  • Excessive sweating
  • Shortness of breath
  • Swelling of the abdomen, legs, or feet

Diagnosis of HLHS

If your doctor suspects your child may have HLHS, they will typically perform a physical examination and review your child's health history. In addition, tests such as echocardiography, electrocardiography, and chest X-rays can help diagnose and evaluate the severity of the condition.

Treatment of HLHS

Treatment of HLHS usually involves a series of corrective surgeries. The goal is to repair the heart defect and improve the baby’s blood flow. Treatment typically begins soon after birth and may include:

  • Surgery to place a prosthetic valve or tubular structure in the aorta to allow better blood flow from the left side of the heart
  • Surgeries to improve the pumping ability of the right ventricle and reduce the strain on the heart
  • A heart transplant if the repairs are not sufficient

Outlook For People With HLHS

The prognosis for patients with HLHS depends on the severity of the condition and how well the treatment works. Most patients who receive treatment in early infancy have a good prognosis and can live relatively normal lives. However, some may experience long-term complications, and some may require lifelong follow-up care and monitoring from a cardiologist.