Hypoplastic left heart syndrome (HLHS) is a rare congenital heart defect in which the left side of the heart is severely underdeveloped. It may affect the left ventricle, aorta, aortic valve, or mitral valve.

Babies born with hypoplastic left heart syndrome usually are seriously ill soon after birth. Hypoplastic left heart syndrome symptoms include:

• greyish-blue skin colour (cyanosis)
• rapid, difficult breathing
• poor feeding
• cold hands and feet
• weak pulse
• unusually drowsy or inactive.

Hypoplastic left heart syndrome can be diagnosed prenatally or after birth via echocardiography. Typical findings include a small left ventricle and aorta, abnormalities of the mitral and aortic valves, retrograde flow in the transverse arch of the aorta, and left-to-right flow between the atria. It is often recognised during the second trimester of pregnancy, between 18 and 24 weeks' gestation.

Surgical operations to assist with hypoplastic left heart are complex and need to be individualised for each patient and must to assess all medical and surgical options on a case-by-case basis

1. Norwood procedure
2. Hybrid procedure
3. Glenn procedure
4. Fontan procedure

Infants undergo either the staged reconstructive surgery (Norwood or Sano procedure within a few days of birth, Glenn or Hemi-Fontan procedure at 3 to 6 months of age, and the Fontan procedure at 1 1/2 to 5 years of age) or cardiac transplantation.