HLHS

Hypoplastic Left Heart Syndrome (HLHS) is a rare congenital heart defect characterized by the underdevelopment of the left side of the heart. This condition affects several key components of the heart, including the left ventricle, mitral valve, aortic valve, and parts of the aorta. The underdevelopment of these areas means that the left side of the heart is unable to effectively pump blood to the body, leading to significant cardiovascular complications.

Etiology

The exact cause of HLHS is not fully understood, but it is believed to involve a combination of genetic and environmental factors. Research indicates a potential link between maternal exposure to certain substances and the development of HLHS, as well as a genetic predisposition to heart defects.

Pathophysiology

In HLHS, the left ventricle is severely underdeveloped, and the mitral and aortic valves are often either too small or completely closed. As a result, the left side of the heart cannot pump oxygenated blood to the body efficiently. Blood returning from the lungs to the left atrium must flow through an atrial septal opening to the right side of the heart, where it is then pumped to the lungs and the body through a patent ductus arteriosus (PDA). This reliance on a PDA for systemic circulation is unsustainable long-term and requires medical intervention.

Symptoms

Symptoms of HLHS may include cyanosis (a bluish tint to the skin, lips, and nails), difficulty breathing, poor feeding, and lethargy. These symptoms typically present within the first few hours or days of life.

Diagnosis

HLHS is often diagnosed prenatally through an ultrasound or shortly after birth through physical examination and echocardiography. An echocardiogram can provide detailed images of the heart's structure and function, helping to confirm the diagnosis.

Treatment

Treatment for HLHS requires surgical intervention, typically conducted in stages. The first stage, known as the Norwood procedure, is performed shortly after birth. This surgery involves reconstruction of the aorta and right ventricle to function as the systemic heart pump. Subsequent surgeries, including the Glenn and Fontan procedures, further redirect blood flow to improve oxygenation and heart function.

Prognosis

The prognosis for children with HLHS has improved significantly with advances in surgical techniques and postoperative care. However, long-term outcomes vary, and individuals with HLHS may face ongoing health challenges and require lifelong medical follow-up.

See also

• Congenital heart defect
• Cardiac surgery
• Pediatric cardiology