Hypoplastic Right Heart Syndrome

Overview

Hypoplastic right heart syndrome (HRHS) is a rare heart problem that a baby is born with. The right side of the heart — the lower chamber called the right ventricle — does not grow properly. Normally, the right ventricle pumps blood to the lungs to pick up oxygen. In HRHS, that chamber is too small and weak to do its job, and the valve and blood vessel leading out of it are often tiny or blocked too. Because of this, less blood reaches the lungs, so the blood that goes around the body carries less oxygen than it should. HRHS is a congenital heart defect, meaning it develops before birth. It is found and treated soon after birth, and children with it need care from a specialist heart team for life.

No. HRHS is rare. It is one of the less common congenital heart defects, and exact numbers vary between countries because it is often grouped with similar conditions such as pulmonary atresia with an intact ventricular septum.

It affects babies from the moment they are born, and it is found in all ethnic groups and in both boys and girls. Because it is a condition you are born with, it is diagnosed in infancy or before birth. Some adults are now living with HRHS after childhood surgery, and they still need specialist follow-up.

Symptoms

Common symptoms

• Bluish or greyish tint to the lips, tongue, skin or fingernails (doctors call this cyanosis)
• Fast or heavy breathing, especially when feeding or crying
• Tiredness and sleeping more than expected
• Poor feeding, sweating during feeds, or slow weight gain
• Cold hands and feet
• A heart murmur heard by a doctor
• Getting out of breath more easily than other children of the same age

Symptoms in children

• Tiring quickly during play or sport compared with friends
• Needing extra rest or naps
• Being smaller or lighter than expected for their age
• Frequent chest infections
• Blue lips or fingertips after activity or in cold weather
• In some children, fainting or dizzy spells — this needs urgent medical advice

Symptoms in older adults

• Ongoing tiredness and lower exercise capacity
• Palpitations (a fluttering or racing heartbeat)
• Swelling of the legs, ankles or tummy
• Shortness of breath, especially lying flat or with activity
• These can be signs of heart strain and should be checked by the heart team promptly

Causes

Main causes

• HRHS happens while the heart is forming in early pregnancy. The right lower chamber and the valve and blood vessel leading out of it do not develop fully.
• In most cases the exact reason is unknown. It is not caused by anything a parent did, ate or felt during pregnancy.
• It is sometimes linked with genetic conditions or with other heart defects, so families may be offered genetic counselling.

Risk factors

• A close family member with a congenital heart defect slightly raises the chance
• Certain genetic syndromes
• Some long-term health conditions in the mother, such as diabetes, if poorly controlled around the time of conception
• Certain medicines, alcohol or infections during early pregnancy — always check any medicine with a pharmacist or doctor before pregnancy
• Having one child with a congenital heart defect means future pregnancies may be monitored more closely

When to see a doctor

See a doctor urgently if:

• Any new blue or grey colour in the lips or skin
• Breathing that is fast, noisy or hard work
• Feeds that are becoming shorter, slower or sweaty
• Unusual sleepiness, floppiness or being hard to wake
• Fever in a baby or child known to have a heart condition
• Palpitations, chest pain or fainting at any age

Book a routine appointment if:

• Scheduled heart clinic appointments — these should not be skipped, even when your child seems well
• Concerns about growth, weight gain or feeding
• Questions about exercise, school, travel or vaccinations
• Planning a pregnancy, if you are an adult with HRHS — speak to the heart team first
• Any new medicines, including over-the-counter ones, so your heart team or pharmacist can check they are safe

Diagnosis

HRHS is often found before birth during a routine pregnancy ultrasound scan, when the heart is looked at in detail. If it is not found then, it is usually picked up in the first hours or days of life because the baby looks blue, breathes fast or has low oxygen levels. A paediatrician or heart specialist will examine the baby, check oxygen levels, and use heart imaging to see how the heart is built and how blood is flowing.

Tests that may be done

• Pulse oximetry — a small clip on the hand or foot that measures oxygen in the blood
• Antenatal (pregnancy) ultrasound and a detailed fetal heart scan
• Echocardiogram — an ultrasound of the heart that shows the chambers, valves and blood flow
• Electrocardiogram (ECG) — sticky patches that record the heart's electrical rhythm
• Chest X-ray to look at heart size and the lungs
• Cardiac catheterisation — a thin tube guided into the heart to measure pressures and oxygen levels
• Cardiac MRI or CT scan for more detailed pictures, often later in childhood
• Blood tests, and sometimes genetic testing

What to expect at your appointment

The first few days can feel like a blur of tests and conversations. Your baby may be cared for in a newborn intensive care unit while the team works out exactly how the heart is built and what support is needed. Ask for things to be explained again in plain words, take notes or bring someone with you, and ask who your main contact is. You are part of the team — your questions and observations about your baby matter.

Treatment

HRHS cannot be 'cured' in the sense of making the heart normal, but it can be treated very effectively. The aim is to make sure enough blood reaches the lungs to pick up oxygen, and then to rebuild the circulation so the heart can work with less strain. Treatment usually starts right after birth, with medicines and support in a specialist unit, followed by a planned series of operations. Every child's plan is different, and the heart team will explain what is recommended for your child.

Self-care at home

• Keep every heart clinic appointment, even when your child is well
• Learn your child's usual feeding pattern and breathing rate so you notice changes early
• Ask your team which vaccinations are recommended, including extra protection such as yearly flu vaccination for the family
• Wash hands often and keep your child away from people with coughs, colds or tummy bugs where you can
• Follow advice on dental care — healthy teeth protect the heart, and your team may advise antibiotics before some dental procedures
• Keep a simple list of your child's medicines and the heart team's contact number with you
• Encourage normal play, school and friendships within whatever limits the team advises

Medical treatments

Newborn treatment often begins with medicines given through a drip to keep a natural channel open so blood can still reach the lungs, plus support with breathing and feeding. Diuretics ('water tablets') may be used to reduce extra fluid, and other medicines may be used to help the heart pump or control rhythm. Which medicines are used, and for how long, is decided by the specialist team and changes over time. Never start, stop or change any medicine without speaking to your heart team or pharmacist, and always check cough, cold and pain remedies with a pharmacist first.

When is surgery considered?

Surgery is almost always needed. It is usually done in stages: an early operation in the first days or weeks of life to secure blood flow to the lungs, a second operation around four to six months of age, and a third operation — often called the Fontan procedure — usually between about two and four years of age. Some children need other operations, catheter procedures or, rarely, a heart transplant. The exact plan depends on your child's heart anatomy and overall health, and the team will discuss it with you in detail.

Living with this condition

Life with HRHS settles into a routine between operations. Children usually go to nursery and school, play with friends and take part in family life. There will be regular heart check-ups, sometimes scans and blood tests, and periods of extra tiredness. As your child grows, help them understand their heart in simple words and encourage them to tell an adult if they feel breathless, dizzy or unwell. Teenagers should gradually learn about their own condition and medicines, so they are ready to manage their care as adults.

Lifestyle tips

• Encourage activity — most children can join in PE and play; ask the heart team about any limits
• Build in rest when needed, especially around colds or busy days
• Avoid smoking and vaping in the home, and keep the car smoke-free
• Keep up with school and hobbies; a normal routine supports confidence and wellbeing
• Plan travel with your team — get advice before long flights or trips to high altitudes, and carry your medical information
• Speak to the team before tattoos, piercings or contact sports

Diet and exercise

Breastfeeding or formula feeding can be hard work for a baby with a heart condition, so expect extra support — some babies need fortified feeds or feeding tubes for a while. As children grow, offer a balanced, varied diet and regular meals. Children with a Fontan circulation may be advised about iron, salt or fluid intake, so follow your team's specific advice rather than generic diets. Exercise is encouraged: walking, swimming, cycling and most school sports are usually fine. Your cardiologist can say whether any activity should be avoided — ask rather than assume.

Mental health and emotional wellbeing

A heart condition affects the whole family, not just the child. It is very common to feel anxious before operations, exhausted by hospital stays, or guilty even though nothing you did caused this. Children and teenagers may feel different from their friends, worry about scars or hospital visits, or feel low. These feelings are understandable and treatable. Talk to your heart team — many hospitals have psychologists or social workers as part of the team. If you or your child ever feel overwhelmed or have thoughts of harming yourself, contact your local crisis line or emergency services straight away. You do not have to cope alone.

Prevention

HRHS cannot usually be prevented, because it develops very early in pregnancy before anyone knows the baby is on the way. It is not caused by anything a parent did. If you are planning a pregnancy and have a family history of congenital heart disease, diabetes, or take regular medicines, a pre-pregnancy conversation with your doctor is a good idea — they can review your health and medicines and arrange extra monitoring if needed.

Vaccines

Vaccinations are especially important for children with heart conditions. Follow the routine childhood schedule for your country, and ask your heart team about extra protection such as a yearly flu vaccination for your child and close family members, and any recommended protection against respiratory infections. Live vaccines may need special discussion in some heart conditions, so always tell the vaccination team about your child's heart.

Screening programmes

During pregnancy, routine ultrasound scans can often detect heart problems, and a detailed fetal heart scan may be offered if something is seen or if there is a family history. Babies are also checked with a pulse oximetry test (a small oxygen sensor) as part of newborn screening in many countries. If you have HRHS yourself, your heart team and obstetric team will plan close monitoring through pregnancy.

Complications

If left untreated

• Dangerously low oxygen levels in the blood
• Severe breathing difficulty and inability to feed
• Heart failure and shock in the newborn period
• Without treatment, the condition is life-threatening in early life

Long-term outlook

The outlook today is very different from what it was a generation ago. Most babies with HRHS survive the newborn period with treatment, and many children grow into teenagers and adults. Life after staged surgery is not always straightforward — some people need further procedures, and tiredness or reduced exercise tolerance is common — but many go to school, work, travel and build relationships. Long-term follow-up at a specialist adult congenital heart service is important, and research keeps improving care. Your child's team can give you the most accurate picture for your child's particular heart.

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