Hypoplastic Left Heart Syndrome (HLHS) is a severe congenital heart defect in which the left side of the heart is underdeveloped. In a normal heart, the left side (consisting of the left atrium and left ventricle) is responsible for pumping oxygen-rich blood to the entire body. In HLHS, the structures on the left side of the heart, including the left ventricle, mitral valve, aortic valve, and the ascending portion of the aorta, are underdeveloped.

Characteristics

  • Underdeveloped Left Ventricle: The left ventricle is too small and cannot effectively pump blood to the body.

  • Mitral Valve and Aortic Valve Abnormalities: These valves may be small, underdeveloped, or completely closed.

  • Small or Narrow Ascending Aorta: The main artery that carries oxygen-rich blood from the left ventricle to the body is underdeveloped.

Symptoms

Babies with HLHS may appear normal at birth but will soon show signs of serious heart failure, including:

  • Difficulty breathing

  • Poor feeding

  • Pale or bluish skin color (cyanosis)

  • Weak pulse

  • Lethargy

Diagnosis

HLHS is often detected before birth during a prenatal ultrasound or shortly after birth due to the presence of symptoms. Diagnostic tests include:

  • Echocardiogram: An ultrasound of the heart to visualize its structure and function.

  • Electrocardiogram (ECG): To measure the electrical activity of the heart.

  • Chest X-ray: To view the size and shape of the heart and lungs.

  • Cardiac catheterization: A procedure to measure pressures within the heart chambers and blood vessels.

Treatment

Treatment for HLHS requires a series of complex surgical procedures performed in stages:

  1. Norwood Procedure: Performed shortly after birth, this surgery reconstructs the aorta and connects it directly to the right ventricle.

  2. Bidirectional Glenn Procedure or Hemi-Fontan Procedure: Performed at 4-6 months of age, this procedure involves redirecting oxygen-poor blood directly from the upper body to the lungs, bypassing the heart.

  3. Fontan Procedure: Usually performed between 18 months and 3 years of age, this final stage directs oxygen-poor blood from the lower body to the lungs.

In some cases, a heart transplant may be considered as an alternative to these surgeries.

Long-term Outlook

Children with HLHS require life-long cardiac care. They may face challenges related to their heart function, growth, development, and may have limitations in physical activity. Despite advancements in surgical techniques and medical care, HLHS remains one of the most challenging congenital heart defects to manage. Regular follow-up with a pediatric cardiologist is essential to monitor heart function, detect complications, and manage any related health issues.