Hypoplastic Left Heart Syndrome (HLHS)

Also known as: HLHS

What is Hypoplastic Left Heart Syndrome?

Hypoplastic left heart syndrome (HLHS) is one of the most complex cardiac defects seen in newborns. Children diagnosed with hypoplastic left heart syndrome have all of the structures on the left side of the heart, which receive oxygenated blood from the lungs, severely undeveloped.

What are the signs/symptoms of HLHS?

Babies with HLHS typically display the following:

  • Lower than normal oxygen saturation
  • Cyanosis, a blue skin color indicating a decrease in oxygen in the bloodstream
  • Difficulty breathing (rapid breathing or shortness of breath)
  • Low pulse
  • Lethargy 

What causes HLHS?

Most of the time this heart defect occurs by chance, with no clear reason for its development.

How is HLHS diagnosed?

Hypoplastic left heart syndrome is one of the most readily diagnosed on fetal echocardiograms and is one of the most common cardiac defects picked up on an obstetrical ultrasounds.

Treatment for Hypoplastic Left Heart Syndrome

Surgery for babies with HLHS will allow their heart to pump blood better to the lungs and the rest of the body. The surgery is conducted in three phases during the first few years of life.

  1. The first phase, called the Norwood procedure, is usually performed in the first weeks of life and includes the building of a new aorta.
  2. The second phase, called the Glenn operation, is usually performed between four and six months of age. This procedure connects the major vein carrying blood from the top half of the body directly to blood vessels to the lungs to get oxygen.
  3. The last phase, the Fontan procedure, is usually performed around three to four years of age. The exact procedures and timing depend on your child’s condition.

Reviewed by: Anthony F. Rossi, MD

This page was last updated on: November 13, 2020 11:19 AM

The Heart Institute: Pediatric Cardiology and Cardiovascular Surgery

The Heart Institute– a world leader in pediatric cardiology and cardiovascular surgery and the care of children with congenital heart disorders – serves as a beacon to families confronting the reality of a child or newborn with a heart defect.

Learn more

Patient Success Stories

Adrien: First Baby Born at Nicklaus Children's Hospital

Emily Granados was 20 weeks pregnant with her third child when she found out something was wrong with his little heart.  Read More.

Learn more about

Cyanosis

A bluish tinge of the lips, tongue, nail beds or skin is called cyanosis. This occurs because of a lack of oxygen in the red cells of blood and is never normal. Learn more

Bidirectional Glenn Procedure

Bidirectional Glenn procedure is one in a series of surgeries performed to get a sufficient amount of blood to the lungs. It is needed when one of the heart’s ventricles doesn’t work well. Learn more

Fontan Procedure

Fontan procedure is a heart surgery used to correct single ventricle type heart defects in children. Learn more