Functional singular ventricle factsheet


The heart is made up of four chambers, two on the top and two on the bottom.

  • atria – the two top chambers that receive the blood that flows into the heart
  • ventricles – the two bottom chambers that pump the blood back out of the heart.

Children with a functional singular ventricle only have one ventricle that is large or strong enough to pump blood back out of the heart. 

Having a functional singular ventricle is a congenital heart defect. A congenital heart defect is a difference in how your child’s heart has grown during pregnancy.

 Signs and symptoms

Signs and symptoms of a functional singular ventricle can range from mild to severe, depending on whether the ventricle:

  • is too small or weak
  • is missing a valve
  • has not grown at all.

Signs and symptoms can look different depending on how severe the condition is. Some common symptoms include:

  • cyanosis – when there is a blue or purple tint to lips, skin, and nails
  • difficulty breathing
  • difficulty feeding
  • being very sleepy or not responding to others
  • weak pulse in the arms and legs  
  • a lower number of wet nappies than expected.


A functional singular ventricle usually develops during the first 8 weeks of pregnancy. This means the condition is usually picked up early on regular ultrasound scans.

If this happens, you will have another scan called a fetal echocardiogram.

The fetal echocardiogram is like the regular ultrasound scans that are done during pregnancy. The scan uses sound waves to show a detailed picture of your baby’s heart, its structure, and how well it is pumping blood. 

A fetal echocardiogram is usually done between weeks 18-24 of pregnancy. If your baby is diagnosed with a heart defect, you will need to have regular scans and checks until your baby is born to make sure there are no other issues. 

Some babies will not have their singular functional ventricle picked up until birth.

Babies who are diagnosed at birth might:

  • look a bit blue
  • have trouble breathing
  • have an abnormal whooshing sound in their heart, known as a murmur.

The paediatrician who checks your baby after they are born will order an echocardiogram to check their heart to diagnose any issues.


Generally, it is not possible to replace or rebuild a ventricle that is missing or not working properly. 

Treatment will focus on supporting the heart to pump blood as well as it can without becoming overworked. 

This will look different for every child, but usually involves a series of surgical procedures done in a specific order.

Norwood procedure (first two weeks of life)

In the Norwood procedure, parts of the heart are reconstructed, and a tube, or shunt, is placed. This helps the right side of the heart pump blood to the body and the lungs. 

This procedure is done to prevent damage to the heart and lungs until the second operation can be done.

Glenn procedure (between 4 and 6 months old)

In the Glenn procedure, the large vein that carries oxygen-poor blood from the upper body is disconnected from the heart. It is then reconnected to the pulmonary artery, which carries blood out of the heart and into the lungs.

This means blood that needs oxygen can go straight to the lungs without passing through the heart. 

Fontan procedure (between 18 months and 4 years old)

In the Fontan procedure, the large vein that carries blood from the lower body is disconnected from the heart. It is then reconnected to the passage that takes blood out of the heart and into the lungs.

This means blood that needs oxygen can go straight to the lungs without passing through the heart. 

After the Fontan procedure, all blood that needs oxygen will travel straight to the lungs without going through the heart.

These procedures aim to: 

  • get the level of oxygen in your child’s blood as close to normal as possible
  • improve their general well-being
  • lower the risk of conditions like stroke, where the brain does not get enough blood.

Staged reconstruction procedures are done using open heart surgery. Open heart surgery is when your child’s doctor opens the chest wall to get access to the heart.

Treatment for your child will depend on their individual needs and may look different depending on the type of heart defect they have.


When to seek help

Children who have had these procedures will need ongoing checkups with their doctors and may need medication to treat any remaining symptoms of their heart condition.

Call your child’s doctor or head to your nearest emergency department if your child has had heart surgery and:

  • stops eating or drinking
  • is vomiting
  • their oxygen levels drop below normal.

Call triple zero (000) for an ambulance if your child has chest pains or trouble breathing.

Last updated Monday 29th January 2024


This factsheet is provided for general information only. It does not constitute health advice and should not be used to diagnose or treat any health condition.

Please consult with your doctor or other health professional to make sure this information is right for you and/or your child.

The Sydney Children’s Hospitals Network does not accept responsibility for inaccuracies or omissions, the interpretation of the information, or for success or appropriateness of any treatment described in the factsheet.

© Sydney Children’s Hospitals Network 2024