Patent ductus arteriosus (often shortened to PDA) is a common heart condition in newborns and young babies, especially those born early, and it affects the way blood flows between the heart and lungs. It can sound frightening to hear that a child has a heart problem, but PDA is usually very treatable and many children go on to live completely normal lives after proper care.
How Blood Normally Circulates Before and After Birth
To understand PDA, it helps to picture how blood circulation changes when a baby is born. Before birth, a baby receives oxygen from the placenta, so the lungs are not yet doing the work of breathing, and blood flow is routed differently to bypass the lungs. After birth, the lungs expand, the baby takes its first breaths, and the heart and blood vessels must quickly adjust so that blood flows to the lungs to pick up oxygen.
During pregnancy, a short blood vessel called the ductus arteriosus connects the pulmonary artery (which normally carries blood to the lungs) to the aorta (the main artery sending blood to the body). This connection is helpful before birth because it allows blood to skip the lungs and go straight out to the body. Shortly after birth, that temporary vessel is supposed to tighten and seal shut as the baby starts breathing air.
What Is Patent Ductus Arteriosus?
Patent ductus arteriosus simply means that the ductus arteriosus has stayed open longer than it should have. “Patent” is a medical term that means “open,” so a PDA is an open connection between the aorta and the pulmonary artery when it is no longer needed. Instead of closing and becoming a solid cord of tissue, this small blood vessel continues to let blood flow between two major arteries.
Because the pressure in the aorta is higher than the pressure in the pulmonary artery, blood is pushed through the PDA from the aorta toward the lungs. That means extra blood ends up in the lung circulation, which can force the heart and lungs to work harder than they should. The effects depend a lot on how big the PDA is and on the baby’s overall health.
Why Does PDA Happen?
The exact reason the ductus arteriosus sometimes stays open is not always clear, but doctors know several risk factors that make PDA more likely. Having a premature baby is one of the strongest risk factors, because in earlier stages of development this vessel is less mature and more likely to stay open after birth. The smaller and earlier a baby is born, the higher the chance that a PDA will be present.
- Prematurity: The closure signals that normally tell the ductus arteriosus to tighten may not be fully established in very early newborns.
- Low birth weight: Babies who are very small at birth often have more fragile circulation and may have trouble with the normal closing process.
- Certain infections during pregnancy: Some maternal infections, especially in early pregnancy, are linked with a higher chance of heart differences in the baby.
- Genetic or chromosomal conditions: Some syndromes and inherited conditions are associated with a greater risk of congenital heart defects, including PDA.
- Family history and other heart defects: A family history of heart problems at birth or the presence of other structural heart differences can make PDA more likely.
Even though these risk factors exist, many babies with PDA have no obvious trigger, and parents should not blame themselves. In most cases, PDA is a chance event in how the baby’s heart and blood vessels finished transitioning after birth.
How PDA Affects the Heart and Lungs
The main issue in PDA is that oxygen-rich blood that has already been pumped out of the heart into the aorta can leak back toward the lungs through the open ductus. This creates a loop where blood recirculates to the lungs instead of moving on to nourish the rest of the body. The larger the PDA, the more extra blood is sent to the lungs with each heartbeat.
Over time, that extra blood flow may:
- Force the left side of the heart to pump harder to keep up.
- Raise pressure in the blood vessels of the lungs.
- Lead to fluid buildup in the lungs, making breathing more difficult.
- Reduce energy for feeding, growth, and normal activity because the heart is working overtime.
Very small PDAs often cause little or no stress to the heart and lungs and may be discovered by chance. Larger ones, or PDAs in very tiny premature infants, can cause more obvious symptoms and need closer monitoring.
Signs and Symptoms Parents Might Notice
Not every baby with PDA looks sick. Some infants, especially older or full-term babies with a small opening, may show almost no outward signs. In these cases, a medical provider may first suspect PDA after hearing a distinctive heart sound during a routine exam. In other babies, the extra blood flow makes everyday activities like breathing and feeding more challenging.
- Fast or labored breathing, especially during feeding or when crying.
- Poor feeding or tiring quickly while eating, which can lead to slow weight gain.
- Increased sweating while feeding or crying.
- Cool hands and feet or lower body compared with the upper body in some cases.
- Frequent respiratory infections, such as repeated colds or chest congestion.
- In more severe cases, signs of heart strain, such as rapid heartbeat or puffiness (swelling) in certain areas.
Sometimes the only clue is the doctor mentioning a heart murmur, which is an extra or unusual sound made by blood moving through the heart or nearby vessels. A murmur is not a disease by itself, but it can alert the clinician to look for structural differences such as a PDA.
How Doctors Diagnose PDA
The process of diagnosing PDA usually begins with a physical examination and listening to the baby’s heart and lungs. If the provider hears a murmur or notices breathing or feeding difficulties, they may order a set of tests to look more closely at the heart and blood flow. These tests are safe and adjusted to be gentle for newborns and young infants.
Common Tests Used
- Stethoscope exam: The provider listens for a characteristic murmur that can suggest blood is moving through an extra opening.
- Echocardiogram (heart ultrasound): This painless test uses sound waves to create moving pictures of the heart and shows the PDA directly, including its size and the direction of blood flow.
- Electrocardiogram (ECG or EKG): Sensors on the chest record the heart’s electrical activity and help detect strain on specific heart chambers.
- Chest X-ray: Images of the chest can show whether the heart appears enlarged or whether there is extra blood flow to the lungs.
- Oxygen monitoring: A small sensor on the skin checks oxygen levels and can reveal if circulation is not balanced.
In most cases, the main test that confirms PDA is the echocardiogram, because it allows the heart specialist to see exactly where the ductus is located and how much blood is passing through it.
