What Is the Ductus Arteriosus

​The ductus arteriosus plays an integral role in the development of a fetus, allowing the majority of blood to flow around the body rather than to the lungs.

However, sometimes, the natural development of this part of the heart doesn’t happen as it should, leading to complications at birth and throughout life.

Below, we’ll explore exactly what the ductus arteriosus is, what patent ductus arteriosus (PDA) is, and what the risk factors of PDA are.

Before he or she is born, a fetus receives oxygen from the placenta (the organ connecting the fetus to the uterus) and their mother.

As the lungs aren’t required, a fetus doesn’t need much blood to go to them in order to help them grow. And that’s where the ductus arteriosus comes into play.

It is a temporary blood vessel that connects the main heart vessel that goes to the lungs (the pulmonary artery) to the main blood vessel (the aorta). This allows the majority of blood to go to the rest of the fetus’s body, bypassing the lungs.

Then, when a baby is born, their lungs are needed, so the chemicals that the body produces to keep the ductus open are stopped. After a few hours or days of the baby being born, this temporary blood vessel gradually becomes narrower and eventually closes.

However, in some cases, it will remain open, and that’s when it becomes the patent ductus arteriosus (PDA).

Small PDAs aren’t often a cause for concern and might not require any treatment. But larger ones can lead to severe complications such as blood (that’s lacking in oxygen) flowing in the wrong direction, heart failure, and weakening of the heart muscle.

What Happens if the Ductus Arteriosus Doesn’t Close? 

If the ductus remains open, blood starts flowing in the opposite direction of what it did when the baby was in the womb – it’s now moving from the aorta to the lungs. When added to the normal blood flow that’s going from the heart to the baby’s lungs, this extra blood can start to cause a buildup in their lungs.

Larger PDAs often cause far too much blood to go to the lungs which makes it hard for the baby to breathe. And it also creates more work for the heart which can result in heart failure.

However, as previously mentioned, the PDA often isn’t large enough to induce heart failure in newborns. Yet if enough blood is flowing to cause an abnormal noise in the baby’s chest (a heart murmur), doctors will recommend that the PDA is closed.

Sometimes, the symptoms of a PDA may occur later on in the baby’s life because of this excess blood flow to the lungs happening over a number of years. These later-stage symptoms include heart failure, pulmonary hypertension, and heart rhythm abnormalities. (Pulmonary hypertension occurs in the blood vessels in the lungs and is caused by high blood pressure).

Another hugely important reason to close PDAs is to prevent the blood vessels that surround the PDA from becoming infected (bacterial endocarditis).

What Are the Symptoms of a PDA? 


These symptoms vary depending on whether the baby is premature or full-term and how big the defect is. Smaller PDAs may go undetected for a longer period of time (perhaps even until adulthood), causing no signs or symptoms, while larger ones can cause indications of heart failure quite soon after they’re born.

Your doctor may pick up on the heart defect when they’re carrying out a regular checkup using a stethoscope to listen to your baby’s heart. But other symptoms to watch out for include:

  • Rapid heart rate
  • Getting tired easily
  • Persistent breathlessness or fast breathing
  • Sweating when they’re eating or crying
  • Poor eating habits that stop them from developing properly

Therefore, if you notice any of these symptoms in your baby or infant, you should contact your doctor for their advice.

What Causes PDA?

As with all congenital heart defects, these conditions arise when there are problems in the early development of the baby’s heart. That said, there isn’t an exact known cause but it is thought that genetics may play a role.

In the US, this is a fairly common condition that’s more common in girls than boys. It’s also more common in babies that are premature, being rare in babies that go full-term. Equally, some children will have other heart defects as well as PDA.  

The Risk Factors for Having a PDA

There are certain factors that may increase your baby’s risk of having a PDA when they’re born. These include:

  • Being female: It is twice as common in girls.
  • Being born at a high altitude: There’s a great risk of a PDA being present if a baby is born above 3,048 meters (10,000 feet) than if they’re born at a low altitude.
  • Family history and certain genetic conditions: If there is a family history of various genetic conditions (e.g. Down syndrome) or heart defects, there is more likelihood of a PDA.
  • Premature birth: It’s more common in babies that are born prematurely than full-term babies.
  • Rubella during pregnancy: If the baby’s mom contracts rubella (German measles) during their pregnancy, there’s an increased risk of heart defects for the baby. This is due to the rubella virus spreading into the baby’s circulatory system after crossing the placenta. Once there, it can damage organs, such as the heart, and blood vessels.

How Is a PDA Treated? 

Smaller openings might not require treatment and may close as the baby gets older. In these cases, the PDA will be monitored by the doctor as the baby grows.

However, where the PDA doesn’t close naturally over time or if it’s quite large and causing problems from birth, medication or surgery may be required to avoid any life-threatening complications.

Medication for PDA


When a baby’s born prematurely, the PDA may be closed using a drug called indomethacin. It’s administered intravenously and gets to work closing off the opening by constricting muscles.

However, this is only effective for newborn babies – further treatments may be necessary for older infants and children.

Catheter Treatments for PDA 

Small PDAs may be treated using a cardiac catheterization procedure. It doesn’t involve opening up the baby’s chest and is frequently done through an outpatient appointment.

A thin flexible tube (a catheter) is guided from the groin of the child, through the blood vessel, to their heart. A blocking device is then passed through the catheter and placed in the PDA. This prevents blood from flowing through the vessel, with the disused vessel eventually being reabsorbed into the baby’s body.

Surgical Treatments for PDA 

Larger PDAs, or PDAs that are left to try and seal on their own to no avail, may need treating with surgery. Typically, this is only carried out on children aged 6 months and over but younger infants may undergo the treatment if they’re presenting the symptoms of a PDA.

When surgery is necessary, a small incision is made between the ribs on the left-hand side of the chest. The ductus is then closed permanently using a small metal clip that squeezes it together or is closed using stitches.

It can take a few weeks for your child to recover from this surgery. And this type of procedure may also be recommended for adults who are suffering from health complications due to a PDA.

What are the risks?

A paralyzed diaphragm, infection, bleeding, and hoarseness.

How Can You Prevent PDA in Your Baby?


There isn’t a definitive way to prevent PDA in your baby, but there are steps you can take to ensure you enjoy a healthy pregnancy that reduces the risks of complications like PDA. These include:

  • Avoiding infections: Make sure your vaccinations are up to date before you conceive. Certain infections (like rubella) can harm your baby.
  • Avoiding risks: These include various substances like cigarettes, alcohol, and illicit drugs. You should also avoid the use of saunas and hot tubs.
  • Eating a healthy diet: This includes ensuring you’re getting enough folic acid (available through a vitamin supplement).
  • Exercising regularly: Develop an exercise plan you are comfortable with, working with your doctor to put one in place.
  • Keeping diabetes under control: Make sure you’re effectively managing and controlling diabetes before you conceive and throughout your pregnancy.
  • Seeking prenatal care: This applies to before you’re pregnant, too, discussing with your doctor all of the things you can change/do to ensure a healthy pregnancy. This includes looking at any medication you’re taking, reducing stress, and quitting smoking.

Equally, if there’s history of heart defects and/or other disorders in your family, it’s worth speaking to your doctor before you conceive.

What Is the Outlook for People with PDA?

Generally, when PDA is detected and treated, the outlook is very positive. The recovery needed when your baby is treated for the PDA depends on whether they have any other illnesses and whether or not they were born prematurely.

Most infants make a good, speedy, and complete recovery without suffering from any complications related to PDA.

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