Neonatal - Patent Ductus Arteriosus

This leaflet is for families or carers of babies who have been found to have a PDA and is intended to give you more information about this condition.

What is a Patent Ductus Arteriosus (PDA)?

The heart contains four chambers, two filling chambers which receive blood from the lungs and the body and two pumping chambers which supply the lungs (via the pulmonary artery) and the body (via the aorta).

Whilst babies are in the womb, their lungs are filled with fluid and as a result very little blood goes to the lungs. The placenta provides the oxygen for the baby.

The ductus arteriosus, often called “the duct,” is a blood vessel between the pulmonary artery and the aorta which allows blood to by-pass the lungs during foetal life. All babies need this connection to survive in the womb.

After birth, when the baby cries and starts to breathe, the fluid in the lungs is replaced by air so the blood can pick up oxygen. As a result, the ductus arteriosus is no longer required and in full term babies usually closes within the first few hours after birth. Blood then circulates to the lungs via the pulmonary artery to be oxygenated.

In some babies, especially babies who are born premature, the duct remains open or ‘patent.’ This is referred to as a patent ductus arteriosus or PDA.

What causes a PDA?

The commonest cause of a PDA is being born prematurely. This is because preterm babies’ blood vessels still have some developing to do and the duct tissue is not as able to constrict after birth.

In addition, premature babies are often poorly and so the levels of oxygen in their blood fluctuate. This can cause the duct to open again, even after it has closed.

Why is PDA important?

If the duct stays open, it can put extra strain on the heart and the lungs. The heart must work harder to cope, not only with its normal job of pumping blood around the body, but also with pumping blood through the ductus into the lungs.

The lungs and their blood supply, in turn, can become overloaded because of the extra blood being pumped through them. This condition is called heart failure (which is completely reversible). This results in increase work of breathing or a need for extra oxygen or more support from the breathing machine.

Finally, the extra blood pumped to the lungs results in low blood flow to the organs in the lower part of the body, particularly the bowel and kidneys, which may interfere with their function such as feeding difficulties. There is also a higher risk of gut inflammation called necrotising enterocolitis (NEC) because the blood flow to the bowel may not be normal.

These conditions may result in a longer stay in hospital and possibly more investigations and treatment which will be discussed in more detail if your child develops these complications. The staff will be observing your child closely for any of these potential complications.

How will it be detected?

A heart murmur (extra heart sound) will be heard by the doctor examining your baby. The team looking after your baby may have suspected a PDA as your baby had difficulty coming off the ventilator or CPAP machine. These signs are not specific, and there may be a PDA without the signs being present. Therefore, if the doctors are concerned that your baby has a ‘significant’ PDA they will arrange for a scan of his or her heart (an echocardiogram or Echo). This will show whether the duct is open and whether it is significant.

Does my baby need any treatment?

There is a lot of uncertainty about how to manage PDA. This includes uncertainty in how best to treat a significant duct. The doctors will consider the balance between possible risks of treatment and possible benefits from closing the duct and will discuss the pros and cons of treatment options with you. There are three options: medicines, surgery, or intervention via a cardiac catheter from the groin. Medical treatment involves giving Paracetamol (the same as you might take for fever or pain relief). This medicine work by narrowing the duct until it eventually closes by itself. Initial treatment is given for three days, this is followed by a repeat echo and if deemed fit a repeat three-day course may be considered.

We may choose to give a water medicine (diuretic) which reduces the amount of fluid on the lungs. These medicines should help your baby’s breathing whilst we wait until the duct closes on its own. We may also reduce the volume of fluid your baby is given in the short term to prevent the lungs becoming too wet.

Finally, if medical treatment is not effective or not suitable for your baby and the doctors still think the ductus is causing significant problems, surgical closure of the ductus will be considered. The decision to offer surgery will be made in consultation with the heart specialists at Alder Hey Children’s Hospital which is where the surgery would be done.

Are there any risks associated with treatment?

Restricting the baby’s fluids is not ideal in the long term as this may also restrict the number of calories and other nutrition necessary for growth. Diuretics can be associated with problems in fluid and salt levels in the body. Paracetamol does have some known side effects including temporarily affecting the liver function. However, we will monitor your baby’s liver function test mid treatment.

Surgical closure of the ductus is a major procedure for a small sick baby, and while it is almost always effective in closing the duct, it may also be associated with significant risks. Most babies who need treatment for a PDA do not experience these adverse effects. However, because they can be significant, and because of the uncertainties regarding treatment, the decision and recommendation to treat is not made lightly. A doctor will discuss the issues fully with you before treatment.

How can I find out more about PDA?

Your baby’s nurses and doctors can give you more information. If the decision is made to recommend surgical closure of the ductus, the heart specialists will discuss this further with you.