Pulmonary atresia: causes, treatment and outlook

Normally, blood low in oxygen leaves the right ventricle through the pulmonary valve into the pulmonary artery and on to the lungs. In pulmonary atresia that route is completely blocked. The Children's Heart Federation adds that the pulmonary artery is often underdeveloped, the right ventricle may be very small, and sometimes the tricuspid valve is also affected, which is why the condition is sometimes called hypoplastic right heart.

Two broad types are described. In pulmonary atresia with intact ventricular septum, usually shortened to PA/IVS, the wall between the two lower chambers is complete and the right ventricle is often small. In pulmonary atresia with a ventricular septal defect, there is a hole in that wall. The BHF notes that some people with PA/IVS also have atrial or ventricular septal defects.

Before birth, a baby's lungs are not used for breathing, and a vessel called the ductus arteriosus connects the circulation. The Children's Heart Federation says that after birth the baby can survive while this duct remains open, because blood can flow through it into the pulmonary arteries and lungs.

As the duct closes in the first days, the baby becomes increasingly blue, with difficulty breathing and feeding. The Federation says most babies need treatment within the first days or months of life. Medicine to hold the duct open buys time. The BHF explains that this medicine, a prostaglandin, helps while the baby waits for surgery.

The NHS says congenital heart disease is screened for at the 20-week pregnancy scan, though that scan cannot find every condition. If a problem is suspected, a specialist fetal echocardiogram gives detailed pictures of the heart and is safe for the baby, according to the BHF. The Children's Heart Federation says that if pulmonary atresia is diagnosed before birth, other tests may be offered because it is commonly seen in children with 22q11.2 deletion.

After birth, a pulse oximetry test uses a painless sensor to check the oxygen in the blood. Other tests listed by the BHF and the Children's Heart Federation include an echocardiogram, an ECG, a chest X-ray, blood tests, and sometimes cardiac catheterisation or an MRI scan. Which tests are used depends on the baby's condition.

• Antenatal scan and fetal echocardiogram

• Pulse oximetry to measure oxygen in the blood

• Echocardiogram to see how blood moves through the heart

• ECG for the heart's electrical activity

• Chest X-ray, blood tests, and in some cases catheter study or MRI

The BHF says the cause of PA/IVS is unknown, although certain factors may raise the chance of a baby being born with a heart condition. The NHS notes that congenital heart disease develops while the heart is forming in the womb, and that sometimes an altered gene passed from a parent is responsible, but often there is no clear reason.

Where a genetic condition such as 22q11.2 deletion is suspected, further tests may be offered, as the Children's Heart Federation describes. Your heart team can explain what is known about the cause in your own child's case.

The aim is to get enough blood to the lungs and the body, and plans differ with the shape of each heart. Options described by the Children's Heart Federation and the BHF include medicine to keep the duct open, a shunt that connects an artery to the pulmonary arteries to increase lung blood flow, and a balloon septostomy that enlarges a hole between the upper chambers.

In some babies, a catheter with a radiofrequency wire can open the blocked pulmonary valve and a balloon then stretches it. The Federation describes this as leaving no scar. Others need open heart surgery. The BHF explains that a valvotomy opens a blocked valve, and that if the right ventricle cannot do its job the plan may move towards a Glenn shunt and then a Fontan procedure, which route the body's blood more directly to the lungs.

The BHF stresses that these are sometimes called palliative procedures because they manage the problem rather than repairing the right ventricle, and that several operations may be needed over time. If the family chooses not to have surgery, or treatment is not possible, the team will support them and the baby will be cared for and kept comfortable.

The Children's Heart Federation says treatment is complicated and it is hard to predict how any one child will do, although most children are much better afterwards. Many continue to have a bluish tinge to the skin. Valves and shunts may need further surgery as a child grows. If the pulmonary valve has been unblocked, it often needs replacing later, sometimes by catheter rather than open surgery.

The BHF says people living with PA/IVS may have less energy and tire faster, which can affect school, exercise and holidays, and planning days with rests can help. They are at higher risk of endocarditis, so antibiotics may be advised around surgery and some dental work. Those who may become pregnant should speak to their heart team before a pregnancy.

The Federation points out that fast heartbeat can follow surgery, that fluid on the lungs and chest infections can occur, and that families may be able to seek benefits such as Disability Living Allowance if a child needs much more care than other children of that age.

A diagnosis in pregnancy or the first days of life is overwhelming. Families are referred to a specialist children's heart team. The BHF mentions its Heart Helpline staffed by cardiac nurses, and describes Little Hearts Matter, a charity for people with single-ventricle conditions, and Tiny Tickers, which supports families from pregnancy onwards.

Ask your team to explain the plan stage by stage, what each operation is meant to achieve and what signs to watch for at home. Keep a written record of medicines and appointments. Your child's dentist should know about the heart condition.