What is patent ductus arteriosus?
Patent ductus arteriosus (PDA) is a heart problem that is usually 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. 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 large amounts of 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, 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, the ductus arteriosus closes within the first few days after birth and blood no longer passes through it.
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.
What causes PDA?
A PDA is 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 reason for a PDA that does not close 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 flowing into the lungs causes higher pressure in the blood vessels. 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.
Premature babies with a PDA 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. The support from the ventilator also may be high, due to this extra blood flow to the lungs. Older infants or children with a PDA may breathe faster than normal or tire easily, but many children do not have obvious problems.
Untreated PDA may lead to long-term lung damage; however, this is uncommon, because most children are treated for their PDA before the lungs get damaged.
What are the symptoms of PDA?
The size of the connection between the aorta and the pulmonary artery will affect the type and severity of the symptoms, as does the age at which they first occur. The larger the opening is, the greater the amount of blood that passes through and overloads the lungs.
A child with a small patent ductus arteriosus might not have any symptoms, and the child’s doctor may have only noted the defect by hearing a heart murmur. Other infants with a larger PDA may exhibit different symptoms. Although each child may experience symptoms differently, symptoms may include:
- 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 and should be discussed with the child’s doctor.
How is PDA diagnosed?
The child’s doctor may hear a heart murmur during a physical examination, and refer the child to a pediatric cardiologist for a diagnosis. A heart murmur is a noise caused by the turbulence of blood flowing through the PDA.
At CHOC, one of our pediatric cardiologists who specializes in the diagnosis and medical management of congenital heart defects will perform a physical examination, listen to the heart and lungs, and make other observations that help in the diagnosis. The loudness and quality of the murmur (such as, harsh or blowing) as well as location within the chest where the murmur is heard best will give the cardiologist an initial idea of which heart problem the child may have. The cardiologist may recommend the following tests:
- 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. Learn more about 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. Learn more about electrocardiogram.
- Echocardiogram (echo). A non-invasive 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. Learn more about echocardiogram.
What is the treatment for PDA?
Specific treatment for PDA will be determined by the child’s doctor based on:
- The child’s age, overall health and medical history
- Extent of the PDA
- The child’s tolerance for specific medications, procedures or therapies
- Expectations for the course of the PDA
- The family’s opinion or preference.
Although a small patent ductus arteriosus may close spontaneously as a child grows, a PDA that causes symptoms will require medical management, and possibly even surgical repair. The child’s cardiologist will check periodically to see whether the PDA is closing on its own. If a PDA does not close on its own, it will be repaired to prevent lung problems that will develop from long-time exposure to extra blood flow. Treatment may include:
- Medical management. In premature infants, an intravenous (IV) medication called indomethacin may help close a patent ductus arteriosus. Indomethacin is related to aspirin and ibuprofen and works by stimulating the muscles inside the PDA to constrict, thereby closing the connection. Diuretics may also be prescribed to help the kidneys remove extra fluid from the body. This may be necessary because the body’s water balance can be affected when the heart is not working as efficiently as it should.
- Adequate nutrition. Most infants with PDA eat and grow normally, but premature infants or those infants with a large PDA may become tired when feeding, and are not able to eat enough to gain weight. Options that can be used to ensure the baby will have adequate nutrition include the following:
– High-calorie formula or breast milk. Special nutritional supplements may be added to pumped breast milk or formula that increase the number of calories in each ounce, thereby allowing the baby to drink less and still take in enough calories to grow properly.
– Supplemental tube feedings. Feedings given through a small, flexible tube that passes through the nose, down the esophagus, and into the stomach, can either supplement or take the place of breast or bottle-feedings. Infants who can drink part of their feeding but not all may be fed the remainder through the feeding tube. Infants who are too tired to breast or bottle-feed may receive their breast milk or formula through the feeding tube alone.
- PDA repair or closure. The majority of children and some infants with PDA are candidates for repair in the cardiac catheterization lab. The goal is to repair the PDA before the lungs become diseased from too much blood flow and pressure and to restore an efficient pattern of blood flow. Surgical repair may also be recommended if more conservative treatments have not been successful. Repair is usually recommended for infants younger than 6 months of age who have large defects that are causing symptoms, such as poor weight gain and rapid breathing. For infants who do not exhibit symptoms, the repair may often be delayed until after 6 to 12 months of age. The child’s cardiologist will recommend when the repair should be performed. Transcatheter closure of the PDA is frequently performed first if possible because it is minimally invasive. Premature infants, because of their small size, are not candidates for this procedure, and require surgical closure of the PDA. If your child’s PDA is closed by a transcatheter method, they may be able to go home the same day, or may possibly stay in the hospital overnight. Your child’s cardiologist will let you know what to expect. Learn more about transcatheter PDA closure.
Your child’s PDA may be repaired surgically in the operating room. The surgical repair, also called PDA ligation, is performed under general anesthesia. The procedure involves closing the open PDA with stitches or clips in order to prevent the surplus blood from entering your child’s lungs. Infants and children who undergo surgical PDA ligation will be cared for in the CVICU after surgery. Your child will be kept as comfortable as possible with medications which relieve pain or anxiety. The staff will also ask for your input about how best to soothe and comfort your child. You will also learn how to care for your child at home before your child is discharged. The staff will give you instructions regarding medications, activity limitations and follow-up appointments before your child is discharged. Most children will only need to stay in the hospital for a few days after the operation.
What is the long-term outlook after PDA surgical repair?
In premature infants, the outlook after PDA surgical repair depends on the following:
- The child’s gestational age
- Any other illnesses present in the baby.
In children born full-term, the vast majority that had a patent ductus arteriosus diagnosed and repaired early will live healthy lives after recovering from the hospitalization. Activity levels, appetite and growth should return to normal. The child’s cardiologist may recommend antibiotics be given to prevent bacterial endocarditis for a specific time period after discharge from the hospital if a coil or occluder device was used.
In children whose PDA was diagnosed very late and/or never repaired, the outlook is uncertain. There is a risk for pulmonary hypertension (increased blood pressure in the blood vessels of the lungs).
Parents should speak with their child’s doctor regarding the specific outlook for your child.