12214 Hypoplastic Left Heart Syndrome Hlhs

Overview

Hypoplastic left heart syndrome (HLHS) is a rare heart condition that is present from birth. In this condition, the left side of the heart (which pumps oxygen-rich blood to the body) does not form correctly. The left lower chamber (left ventricle) is very small and weak, and the main blood vessel leaving the heart (aorta) is also underdeveloped. Because the left side cannot pump enough blood, the right side of the heart must try to do all the work, but it cannot do this for long without help. HLHS is a serious condition that requires surgery soon after birth and lifelong follow-up care.

HLHS is rare. It affects about 1 in 5,000 babies born each year. It is one of the most serious heart defects a baby can be born with.

HLHS is present from birth. It is usually diagnosed during pregnancy or shortly after a baby is born. It affects both boys and girls. Because of modern surgery, many children with HLHS grow into adults, so it can also affect people in their 20s, 30s, and beyond.

Symptoms

Common symptoms

• Rapid or difficult breathing, especially with feeding
• Poor feeding, tiring easily while eating, or sweating during feeds
• Bluish or grayish color of the lips, skin, or nail beds (cyanosis)
• Cold hands and feet
• Weak pulse or a pulse that feels unusually strong in the upper body but weak in the legs
• Lethargy or being unusually sleepy and hard to wake

Symptoms in children

• Older children with HLHS who have had surgery may still have some symptoms, such as getting tired more easily than other children during exercise.
• They may have trouble gaining weight and growing as expected.
• Some children may have learning or developmental delays, although many others are in line with their peers.

Symptoms in older adults

• Adults with HLHS can experience fatigue, shortness of breath, and heart rhythm problems.
• Some may develop swelling in the feet or legs due to heart failure.
• They need lifelong check-ups with a specialist in adult congenital heart disease.

Causes

Main causes

• The exact cause of HLHS is not fully understood, but it happens early in pregnancy when the heart is forming.
• Most cases occur for no known reason, and are not caused by anything the mother did during pregnancy.
• HLHS may be linked to genetic changes or be part of a larger syndrome (a set of health problems present from birth).

Risk factors

• Having a family history of congenital heart disease.
• Having a genetic condition, such as Turner syndrome or other chromosomal disorders.
• Being the child of a parent who has a congenital heart defect (though the risk is still low).

When to see a doctor

See a doctor urgently if:

• If your baby has any of the emergency symptoms listed above, such as blue lips or skin, severe breathing trouble, or fainting, call your local emergency number immediately.
• If you are pregnant and your ultrasound shows a possible heart problem, your doctor will refer you to a specialist for a detailed scan and plan.

Book a routine appointment if:

• If your baby is feeding poorly, breathing faster than normal, or seems unusually tired, contact your pediatrician or family doctor without delay.
• If your child has HLHS, keep all scheduled visits with the pediatric cardiologist (heart specialist for children), even if your child seems well.

Diagnosis

HLHS is often diagnosed before birth during a routine ultrasound scan. If the scan shows signs of a heart problem, a detailed echocardiogram (an ultrasound of the heart) will be done to confirm the diagnosis. If not found before birth, it is usually noticed in the first days after birth, when a baby appears blue or struggles to feed and breathe.

Tests that may be done

• Echocardiogram (heart ultrasound) – a painless scan that shows the structure and pumping function of the heart.
• Pulse oximetry – a small sensor on the finger or foot to measure oxygen levels in the blood.
• Electrocardiogram (ECG) – a quick test that records the heart's electrical activity.
• Chest X-ray – a picture of the heart and lungs to check their size and shape.
• Cardiac catheterization – a thin tube is used to look inside the heart, but this is often done later or before surgery if more detail is needed.

What to expect at your appointment

If HLHS is suspected, your baby will be referred to a pediatric cardiology team at a specialist children's hospital. You will meet multiple specialists who explain the condition and the treatment path. The team will work with you to plan the best care for your baby, including timing of medications before surgery and the step-by-step surgeries that will be needed.

Treatment

Treatment for HLHS involves a series of complex heart surgeries, called staged surgery, that redirect blood flow so the right side of the heart can pump blood to the whole body. These surgeries are not a cure, but they allow the heart to work more effectively. Some babies may need a heart transplant if surgery is not possible or does not work well. Treatment is always individualized, and a team of specialists will discuss the best approach for your child.

Self-care at home

• If your baby is diagnosed with HLHS, they will need to be in a hospital where heart specialists are available. You can hold, comfort, and feed your baby as soon as the medical team says it is safe.
• Before and after surgery, carefully follow the feeding plan from your heart team. Many babies need extra calories to grow, and some may need a feeding tube for a while.
• Give all prescribed medicines exactly as directed by your child's cardiologist. Do not stop or change any medicine without talking to the doctor.

Medical treatments

Before and between surgeries, babies may receive medicines to help the heart pump, balance blood flow, or keep blood pressure stable. After the final stage of surgery, many children take low-dose medicines to protect the heart and blood vessels. All medicines are prescribed and monitored by a specialist. There are also surgical options, which are done in stages: the first surgery is usually in the first weeks of life, the second at around 4 to 6 months, and the third at around 2 to 4 years old.

When is surgery considered?

Surgery is always needed for HLHS. The first operation (often called the Norwood procedure, but there are variations) is usually done within the first 1 to 2 weeks of life. The second stage (often called a Glenn or hemi-Fontan) is done around 4 to 6 months of age. The third stage (often called the Fontan) is typically done between 2 and 4 years of age. Each surgery carries risks, and the medical team will explain them fully.

Living with this condition

Living with HLHS means regular visits to the cardiologist, usually every few months to a year, for check-ups, ultrasound scans, and ECGs. Feeding, growth, and weight gain are important, especially in the first few years. Most children with HLHS can go to school, play, and have a full family life, but they may need to avoid very strenuous exercise. As they grow, they will transition from a pediatric heart specialist to an adult congenital heart specialist.

Lifestyle tips

• Keep regular check-ups with the heart specialist and primary care doctor.
• Follow a heart-healthy lifestyle as your child grows, including not smoking or vaping, limiting alcohol, and staying active as advised by the cardiologist.
• Maintain good dental hygiene and see a dentist regularly, because mouth infections can spread to the heart.
• Know the signs of infection and fever, and call your doctor early if your child becomes ill.

Diet and exercise

Babies with HLHS often need extra calories, either through enriched breastmilk or formula, and sometimes a feeding tube to help them gain enough weight. Older children and adults should eat a balanced diet with plenty of fruits and vegetables, and their cardiologist will advise on salt and fluid intake if needed. Exercise is usually encouraged, but the type and intensity depend on the individual. Many can do normal activities, but competitive or high-intensity sports may be limited. Always ask the cardiologist what is safe.

Mental health and emotional wellbeing

A diagnosis of HLHS can feel overwhelming for parents and children. It is normal to feel anxious, scared, or sad. Children with HLHS may face extra challenges at school or in social situations. It is important to talk openly about feelings, and to seek support from family, friends, or a counselor. Parents also need support—not just for the child, but for themselves. Remember that taking care of your own mental health helps you care for your child.

Prevention

In most cases, HLHS cannot be prevented, because it happens early in pregnancy for unknown reasons. However, health care professionals recommend that all people who are pregnant or planning a pregnancy take a multivitamin that includes folic acid (as advised by their midwife or doctor) and attend regular prenatal appointments. If there is a family history of congenital heart disease, genetic counseling may be helpful.

Vaccines

All babies and children should receive their routine vaccinations according to the standard schedule. In addition, children with HLHS may be advised to have the annual flu shot (influenza vaccine). Your heart team will recommend which vaccines are right for your child, and it is safe for most children with HLHS to receive them. Ask your doctor if you have any questions.

Screening programmes

Prenatal ultrasound scans during pregnancy can see the heartʼs structure and often detect HLHS before birth. Some countries also do a pulse oximetry blood oxygen test on all newborns shortly after birth, which can identify some congenital heart defects early. If you are expecting a baby, ask your midwife or doctor about your screening options.

Complications

If left untreated

• Without treatment, the left side of the heart cannot pump enough blood to the body, leading to dangerously low oxygen levels and shock within the first days or weeks of life.
• Untreated HLHS is nearly always fatal in early infancy.
• Even with surgery, there are risks such as heart rhythm problems, fluid buildup in the body (edema), and reduced exercise tolerance.

Long-term outlook

The outlook for a baby born with HLHS is far brighter than it was a few decades ago. Thanks to improved surgery and medical care, about 7 in 10 babies survive to adulthood. Many children with HLHS lead active, full lives, although they need lifelong follow-up and may need extra surgeries over time. Every child is different, and your heart team will work closely with you to give your child the best possible future. There is much hope, and a growing community of adults with HLHS living meaningful lives.

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