Hypoplastic left heart syndrome factsheet
Introduction
The heart has four chambers - two at the top and two at the bottom.
- atria - the two top chambers that receive blood flowing into the heart
- ventricles - the two bottom chambers that pump blood out of the heart.
Hypoplastic Left Heart Syndrome (HLHS) is a condition where the left side of the heart doesn't develop properly, making it hard for the heart to pump enough blood to the body. In HLHS, the right side of the heart has to work extra hard, which can cause problems over time.
HLHS 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
Symptoms of HLHS can show up right after birth or a few days later.
They can include:
- cyanosis – a bluish tint to lips, skin, and nails
- trouble breathing
- difficulty feeding
- fast heartbeat
- extreme sleepiness or unresponsiveness
- weak pulse in arms and legs
- fewer wet nappies than usual
- cold hands and feet.
Diagnosis
HLHS can be found during pregnancy using a foetal echocardiogram, which shows detailed pictures of the baby's heart and how well it's working.
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 tests including:
- chest x-ray - to show the size and shape of your baby’s heart and lungs
- echocardiogram - an ultrasound that shows internal heart structures
- electrocardiogram (EKG) – to measure the electrical changes that happen when your baby’s heart beats
- pulse oximetry screening – a foot or hand monitor that tells you how much oxygen is in your baby’s bloodstream.
When HLHS is diagnosed, your child will see a heart specialist called a cardiologist.
Treatment
Generally, it is not possible to fix missing or poorly working parts of the heart.
HLHS is treated with medication and a series of surgeries that 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.
Some babies will need a new heart donated by another person. This is called a heart transplant.
Norwood procedure (first two weeks of life)
The Norwood procedure involves reconstructing parts of the heart and placing a tube or shunt to help the right ventricle pump blood to the body and lungs. It is done in the first few weeks of life to prevent damage to the heart and lungs until the second operation.
This procedure is done to prevent damage to the heart and lungs until the second operation can be done.
There is a higher risk of this operation not working correctly, compared to when it is used in other heart conditions.
Bidirectional Glenn shunt operation (at 4-6 months)
The surgeon replaces the old shunt with a new shunt that lets blood flow straight into the lungs. This lowers the strain on the right side of the heart.
Fontan procedure (18 months-4 years old)
The pulmonary artery carries blood to the lungs, picking up oxygen and releasing carbon dioxide, a waste.
The large vein called the inferior vena cava carries blood that needs oxygen from the lower body into the heart.
In the Fontan procedure, the inferior vena cava is connected to the pulmonary artery. This allows all blood that needs oxygen to flow directly to the lungs.
Management
Risk factors
HLHS and other heart defects can be passed down in families.
Before planning a pregnancy, see a genetic counsellor if:
- you or someone in your family has a heart defect
- you have a child with a heart defect.
A genetic counsellor is a health professional who can give families information about:
- different conditions that can be passed down
- what the effects on their child might be
- how to manage or treat the condition
- what support is available.
What to expect after surgery
Every child with HLHS is different. Your doctor will explain your child's condition, the procedures needed, and their chances of recovery. While these procedures can't make the heart normal, they aim to help it work as well as possible.
Children who have had these procedures need regular check-ups and may spend some time in the hospital between surgeries. They will also need medication to manage some symptoms.
