Congenital heart defects

What are congenital heart defects?

Congenital heart defects are present in about six out of 1,000 of babies. They take the form of holes between the chambers, blockages in the pathways from the heart to the lungs or the body, or abnormal connections between the chambers and vessels of the heart.

Types of congenital heart defect

Holes in the heart can occur:

• In the upper chambers (atrial septal defects)
• In tower chambers (ventricular septal defects)
• Between all four chambers (atrioventricular septal defects)
• In the great artery, which is called patent ductal arteriosus

The holes are part of the circulation system in the foetus but should close up after birth.

More complex conditions include tetralogy of Fallot. The main symptom is cyanosis, and for this reason babies with this problem are commonly known as 'blue babies'.

In tetralogy of Fallot, the baby has a large hole in the heart, allowing blood to pass from the right ventricle to the left without going through the lungs. There is a narrowing at or just below the pulmonary valve, the right ventricle is more muscular than normal and the aorta lies directly over the hole - the ventricular septal defect.

Babies may have rapid breathing or fall unconscious. Older children may become short of breath and faint.

An obstruction, or stenosis, can occur between the valves between the upper and lower chambers of the heart. More frequently, the obstruction is between the ventricles and trunks coming from them, either the valve to the lungs or the valve to the body.

Only severe aortic stenosis requires surgery, and some children may have the condition without showing any symptoms. The obstruction can also be within the vessels themselves. In this case, the narrowing is within the artery and effects supplies of blood to different parts of the body. This defect may not be picked up for many years.

Causes of congenital heart defects

Causes are thought to include:

• Development problems during pregnancy, sometimes as a result of a viral infection such as rubella contracted by the mother
• Alcohol, illegal drugs and over-the-counter medicines can also cause defects
• Maternal diabetes
• Genetic conditions, such as Down’s syndrome

Diagnosing congenital heart defects

Diagnosis can be made by scans taken during pregnancy, but is usually made in the first days or weeks after birth. In some cases, however, diagnosis may not be made until much later in life.

Treatment of congenital heart defects

In tetralogy of Fallot, surgery may be needed to increase blood flow to the lungs with a shunt, linking the aorta and the pulmonary artery. The child is able to develop and the defect can be corrected later.

An arterial switch operation may be necessary to reconnect the arteries correctly. With holes in the heart, oygenated, red blood from the lungs passes into the right side of the heart, where it mixes with bluish blood and is sent back to the lungs. The heart is put under extra strain, potentially causing it to enlarge and causing high blood pressure and blood vessel damage. Growth and nourishment are affected.

Holes in the heart are closed with one or two patches and the single valve is divided into two. Blood circulation should be returned to normal but the reconstructed valve may not work normally.

If the defect is too complex to repair in infancy, a pulmonary artery band may be surgically used to reduce blood flow and high pressure in the lungs (pulmonary hypertension). The band is later removed and surgery carried out.

Balloon valvuloplasty, which involves threading a balloon through a dilated heart valve, is usually used to correct pulmonary valvular stenosis, although open-heart surgery may be necessary.

Advice and support

• British Heart Foundation
• Heart HelpLine: 0300 330 3311
• Website: www.bhf.org.uk

• HeartLine Association
• Tel: 0330 022 4466
• Website: www.heartline.org.uk

• Children's Heart Federation
• Tel: 0808 808 5000
• Website: www.childrens-heart-fed.org.uk