Congenital heart disease

About one in every 100 babies is born with a heart defect, known as a congenital heart defect (CHD). Some defects are mild and do not significantly affect how the heart works. However, more than half of children with CHD have a condition serious enough to need treatment.

How the heart works#

The heart is a double pump made up of four chambers. Its job is to supply the body with oxygen. Blood moves through these stages:

• Blood low in oxygen enters the right collecting chamber (right atrium) and is squeezed into the right pumping chamber (right ventricle).
• From there it is pumped through an artery to the lungs, where it picks up oxygen.
• Oxygen-rich blood returns to the left collecting chamber (left atrium), passes into the left pumping chamber (left ventricle), and is pumped into the main artery (the aorta) to begin its journey around the body again.

How heart defects develop#

If the heart and blood vessels do not grow properly during fetal development, this may cause:

• blockages that prevent blood flowing normally through the heart and arteries
• blood to travel abnormally through the heart, for example across ‘holes’ in the walls that separate the two sides
• parts of the heart itself to be underdeveloped

Acquired heart disease#

Some children develop a heart problem after an illness. These are called acquired heart disorders. Illnesses that can lead to a heart problem include:

• Kawasaki disease (an illness with fever and swollen lymph glands that may affect the heart)
• myocarditis (inflammation of the heart muscle)
• cardiomyopathy (disease of the heart muscle)
• rheumatic heart disease (which may follow a streptococcal bacterial infection)

Some children with genetic conditions, such as Noonan syndrome, can also have heart abnormalities.

Causes of congenital heart disease#

In around 8 out of 10 cases, the reason for a congenital heart defect is unknown. Known causes and risk factors include:

• Genes – about 20 per cent of cases have a genetic cause.
• Other birth defects – a baby with certain conditions, such as Down syndrome, is more likely to have heart malformations.
• Maternal illness – an illness during pregnancy, such as rubella (now rare), may increase the risk.
• Medication and drugs – some medicines (over-the-counter or prescription) and illicit drugs taken during pregnancy may increase the risk.
• Alcohol – drinking large amounts of alcohol during pregnancy may increase the risk.
• Maternal health – factors such as unmanaged diabetes and poor nutrition during pregnancy.
• Maternal age.

Symptoms of congenital heart disease#

Heart problems can cause a range of symptoms in babies, including:

• shortness of breath, which may be due to a build-up of fluid in the lungs
• difficulty feeding, sometimes because the baby is having trouble breathing
• blue lips and skin (cyanosis), which can happen when oxygen-poor blood from the veins mixes with oxygen-rich blood from the lungs

Five common heart defects#

Ventricular septal defect#

A ventricular septal defect is one of the most common congenital heart defects. The ventricles are the two lower pumping chambers of the heart, and this defect means there is a hole in the wall between them. The hole lets oxygenated and deoxygenated blood mix.

The heart then has to work much harder than normal and may enlarge. Symptoms include breathlessness, difficulty feeding, increased heart rate and failure to grow at the expected rate. Depending on severity, a child may develop congestive heart failure and an increased risk of pneumonia.

Treatment depends on the size of the defect. A small hole may close on its own over time, needing only careful monitoring. Large defects that cause symptoms in infancy may require open-heart surgery to close the hole, usually with a ‘patch’, allowing blood to circulate normally and relieving strain on the heart. In some cases, generally in older children whose hole has not closed, a catheter procedure may close the defect with an implantable device.

Transposition of the great vessels#

Normally the pulmonary artery carries blood from the right ventricle to the lungs, and the aorta carries blood from the left ventricle to the body. In transposition of the great vessels this is reversed: the pulmonary artery is attached to the left ventricle and the aorta to the right, so oxygenated blood is pumped back to the lungs instead of around the body.

This defect can be fatal in the early weeks of life if untreated. Some babies survive longer if there is a hole between the upper or lower chambers that lets blood mix. The main symptom is cyanosis. Treatment involves a procedure called balloon septostomy to enlarge the small opening between the atria that is normally present at birth, so more oxygenated blood can reach the body. Further surgery is usually arranged within the first two weeks of life to reconnect the arteries normally.

Coarctation of the aorta#

The aorta is the body’s main artery, and ‘coarctation’ means it is narrowed or pinched, usually in the upper chest. This lowers blood pressure in the lower body. Symptoms typically appear in the first week of life and include breathlessness and difficulty breathing, and may include collapse. Less commonly, the condition is not found in infancy and is discovered later in life during investigations for high blood pressure.

Surgery is needed when the condition is severe and causes symptoms in early infancy. In older children, the narrowed section can sometimes be widened with special balloons or ‘stents’.

Tetralogy of Fallot#

In tetralogy of Fallot, the heart is affected by four main defects:

• a ventricular septal defect
• blockage of blood flow out of the right ventricle
• thickening of the wall of the right ventricle
• displacement of the aorta towards the right ventricle

Together these allow oxygenated and deoxygenated blood to mix inside the heart. The main symptom is cyanosis that develops in the early weeks or months of life. Treatment requires surgery to close the septal defect and remove the obstruction to blood flow out of the right ventricle. Some infants with severe early symptoms may first have a ‘shunt’ operation, which increases blood flow to the lungs and relieves cyanosis but does not correct the underlying defect.

Hypoplastic left heart syndrome#

In this condition, the entire left side of the heart, including the valves and blood vessels, is underdeveloped. Without prompt treatment, the baby is likely to die within days or weeks of birth. Symptoms include a grey complexion and severe breathing difficulties.

Hypoplastic left heart syndrome requires surgery. One technique is a ‘Norwood’ operation, which allows the right ventricle to become the pumping chamber that supplies both the body and the lungs. This surgery is difficult and carries high risk, and at least two further operations in early childhood are needed to achieve normal heart function.

Caring for a child with a heart defect#

Children with heart defects need special care to prevent infections. Ask your child’s cardiologist whether your child needs antibiotics for some procedures, such as having teeth removed or other surgery involving the mouth, nose, intestinal organs or genito-urinary system. Bacteria can enter the bloodstream during these procedures and cause a serious infection (infective endocarditis) in the abnormal part of the heart.

All medications should be checked with the pharmacist, family doctor or cardiologist. The usual immunisations should be given at the normal times, following advice from your doctor.

Key points#

• About one in 100 babies is born with a congenital heart defect.
• Some defects are mild, but more than half of children with CHD need treatment.
• In around 8 out of 10 cases the cause is unknown; known factors include genes, other birth defects, maternal illness, and medications, drugs or alcohol during pregnancy.
• Common symptoms in babies include shortness of breath, difficulty feeding and blue lips and skin (cyanosis).
• Children with heart defects need special care to prevent infections.

Where to get help#