Patent Ductus Arteriosus (PDA)

What is PDA?

Anatomy of the heart, normal

PDA is a heart problem that is frequently noted in the first few weeks or months after birth. It is characterized by the persistence of a normal fetal connection between the aorta and the pulmonary artery which allows oxygen-rich (red) blood that should go to the body to recirculate through the lungs.

All babies are born with this connection between the aorta and the pulmonary artery. While your baby was developing in the uterus, it was not necessary for blood to circulate through the lungs because oxygen was provided through the placenta. During pregnancy, a connection was necessary to allow oxygen-rich (red) blood to bypass your baby's lungs and proceed into the body. This normal connection that all babies have is called a ductus arteriosus.

At birth, the placenta is removed when the umbilical cord is cut. Your baby's lungs must now provide oxygen to his or her body. As your baby takes the first breath, the blood vessels in the lungs open up, and blood begins to flow through them to pick up oxygen. At this point, the ductus arteriosus is not needed to bypass the lungs. Under normal circumstances, within the first few days after birth, the ductus arteriosus closes and blood no longer passes through it.

Illustration of the anatomy of a heart with a patent ductus arteriosus

In some babies, however, the ductus arteriosus remains open (patent) and the condition now becomes known as patent ductus arteriosus (PDA). The opening between the aorta and the pulmonary artery allows oxygen-rich (red) blood to recirculate into the lungs.

Patent ductus arteriosus occurs twice as often in girls as in boys.

Prevention & Risk Treatment

Prevention & Risk Treatment

What causes PDA?

A PDA is almost always present at birth. In some children, the PDA does not close. Although exact reasons why this happens in some patients and not in others are not known, the most common association for a PDA is prematurity.

PDA can also occur in combination with other heart defects.

Why is PDA a concern?

When the ductus arteriosus stays open, oxygen-rich (red) blood passes from the aorta to the pulmonary artery, mixing with the oxygen-poor (blue) blood already flowing to the lungs. The blood vessels in the lungs have to handle a larger amount of blood than normal. How well the lung vessels are able to adapt to the extra blood flow depends on how big the PDA is and how much blood is able to pass through it from the aorta.

Extra blood causes higher pressure in the blood vessels in the lungs. The larger the volume of blood that goes to the lungs at high pressure, the more the lungs have to cope with this extra blood at high pressure.

Children may have difficulty breathing because of this extra blood flow to the lungs at high pressure. They may remain on the ventilator for a longer period of time if they are premature. The support from the ventilator also may be high, due to this extra blood flow to the lungs.

Rarely, untreated PDA may lead to long-term lung damage. This is uncommon, however, since most children will have been treated for their PDA before the lungs get damaged.

Often, the PDA may be "silent," that is, causing no symptoms. This is especially true in older patients (beyond the first few months of life) with small PDAs.

What are the symptoms of PDA?

The size of the connection between the aorta and the pulmonary artery will affect the type of symptoms noted, the severity of symptoms, and the age at which they first occur. The larger the opening, the greater the amount of blood that passes through that overloads the lungs.

A child with a small patent ductus arteriosus might not have any symptoms, and your child's doctor may have only noted the defect by hearing a heart murmur. Other infants with a larger PDA may exhibit different symptoms. The following are the most common symptoms of PDA. However, each child may experience symptoms differently. Symptoms may include:

  • Fatigue
  • Sweating
  • Rapid breathing
  • Heavy breathing
  • Congested breathing
  • Disinterest in feeding, or tiring while feeding
  • Poor weight gain

The symptoms of a PDA may resemble other medical conditions or heart problems. Always consult your child's doctor for a diagnosis.

Diagnosis

Diagnosis

How is PDA diagnosed?

Your child's doctor may have heard a heart murmur during a physical examination, and referred your child to a pediatric cardiologist for a diagnosis. In this case, a heart murmur is a noise caused by the turbulence of blood flowing through the PDA.

A pediatric cardiologist specializes in the diagnosis and medical management of congenital heart defects, as well as heart problems that may develop later in childhood. The cardiologist will perform a physical examination, listening to the heart and lungs, and make other observations that help in the diagnosis. The location within the chest where the murmur is heard best, as well as the loudness and quality of the murmur (such as, harsh or blowing) will give the cardiologist an initial idea of which heart problem your child may have. Diagnostic testing for congenital heart disease varies by the child's age, clinical condition, and institutional preferences. Some tests that may be recommended include the following:

  • Chest X-ray. A diagnostic test that uses invisible X-ray beams to produce images of internal tissues, bones, and organs onto film. With a PDA, the heart may be enlarged due to larger amounts of blood flow recirculating through the lungs back to the heart. Also, there may be changes that take place in the lungs due to extra blood flow that can be seen on an X-ray.
  • Electrocardiogram (ECG or EKG). A test that records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias), and detects heart muscle stress.
  • Echocardiogram (echo). A procedure that evaluates the structure and function of the heart by using sound waves recorded on an electronic sensor that produce a moving picture of the heart and heart valves. An echo can show the pattern of blood flow through the PDA, and determine how large the opening is, as well as how much blood is passing through it. An echo is the most common way that a PDA is diagnosed.
  • Cardiac catheterization. A cardiac catheterization is an invasive procedure that gives very detailed information about the structures inside the heart. Under sedation, a small, thin, flexible tube (catheter) is inserted into a blood vessel in the groin, and guided to the inside of the heart. Blood pressure and oxygen measurements are taken in the four chambers of the heart, as well as the pulmonary artery and aorta. Contrast dye is also injected to more clearly visualize the structures inside the heart.

The cardiac catheterization procedure may also be an option for treatment. During the procedure, the child is sedated and a small, thin, flexible tube (catheter) is inserted into a blood vessel in the groin and guided to the inside of the heart. Once the catheter is in the heart, the cardiologist will pass a special device, either a coil or a PDA occluder (depending on the size of the PDA). This device will close the PDA and therefore stop the blood flow through the PDA.

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"The doctors and staff of Children's National mend the broken hearts of not only the children, but the family of those children as well. My son is alive and well today because of the miracle that happened at Children's National."

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