PDA ligation is a surgical procedure that closes a small blood vessel called the ductus arteriosus when it fails to shut on its own after birth. This vessel normally closes within the first few days of life, but when it stays open (called a patent ductus arteriosus, or PDA), it can force too much blood into the lungs and strain the heart. The procedure is most commonly performed on premature infants and has been done successfully since 1939, when surgeons Robert Gross and John Hubbard reported the first case.
Why the Ductus Arteriosus Matters
Before birth, a baby’s lungs don’t do any breathing. Oxygen comes from the placenta instead. The ductus arteriosus is a short blood vessel that routes blood away from the lungs and into the body’s main artery, the aorta. Less than 10% of the blood leaving the right side of the heart actually reaches the lungs during fetal life. This is completely normal and necessary.
After birth, the baby starts breathing and the lungs take over. The ductus arteriosus typically closes within hours to days, becoming a small, harmless remnant. When it stays open, blood flows backward through it, from the aorta into the lungs. This “left-to-right shunt” floods the lungs with excess blood, causing fluid buildup (pulmonary edema) and forcing the left side of the heart to work harder to keep up. Over time, the left chambers of the heart enlarge from the extra workload.
When Ligation Becomes Necessary
Not every PDA needs surgery. Doctors first try medication, typically anti-inflammatory drugs that encourage the vessel to constrict and close. Ligation is considered when one or two rounds of medication fail, when the baby can’t tolerate the medication, or when symptoms are worsening despite treatment. The signs that push toward surgery include difficulty weaning off a ventilator, poor weight gain, and heart failure symptoms caused by the extra blood flow to the lungs.
Doctors use echocardiography to measure how significant the shunt is. A duct wider than 1.5 millimeters, an enlarged left atrium relative to the aorta, reversed blood flow in the aorta at the end of each heartbeat, and poor heart function all point toward a PDA that needs intervention. Premature babies born before 28 weeks or weighing under 1,000 grams are especially vulnerable because their lungs and hearts are least equipped to handle the extra strain.
How the Surgery Works
During a traditional PDA ligation, the baby is placed on their right side under general anesthesia. The surgeon makes a small incision below the left shoulder blade, working between the ribs to access the chest cavity. The left lung is gently moved aside to expose the aorta and locate the open duct.
The surgeon carefully separates the duct from surrounding tissue, taking particular care to identify and avoid the left recurrent laryngeal nerve, which runs near the duct and controls one of the vocal cords. Once the duct is isolated, it is tied off with surgical thread in two places and a small titanium clip is placed between the ties for extra security. The surgeon then re-expands the lung, confirms there’s no bleeding or air leak, and closes the chest. In many cases, no drainage tube is needed afterward.
Bedside Ligation in the NICU
For the smallest and most fragile babies, transporting them to an operating room carries real risk. These infants can lose body heat rapidly, and moving them away from their life-support equipment is dangerous. Instead, surgical teams bring the operation to the baby’s bedside in the neonatal intensive care unit.
The setup is remarkably adapted to the NICU environment. The team uses specialized incubators with removable walls and roofs. The room is heated to body temperature (37°C) before surgery, and the baby’s head and limbs are covered to prevent heat loss. Portable lamps and headlamps replace overhead surgical lights. A cardiac surgeon, anesthesiologist, neonatal specialist, and two nurses make up the bedside team. Studies confirm this approach is safe in both full-term and premature babies.
Video-Assisted Thoracoscopic Surgery
In larger infants and children, surgeons can perform PDA ligation using a camera-guided technique called VATS. Instead of spreading the ribs apart, the surgeon inserts a small camera and instruments through tiny incisions. This preserves the muscle architecture of the chest wall and avoids the rib-spreading that can lead to chest asymmetry or spinal curvature (scoliosis) later in life. VATS generally results in shorter surgical times, shorter hospital stays, and better cosmetic outcomes compared to open surgery. If complications arise during the procedure, the surgeon can convert to a standard open approach.
Catheter-Based Closure as an Alternative
PDA ligation is not the only option. Transcatheter closure uses a thin tube threaded through a blood vessel in the leg to deliver a small plug or device that blocks the open duct from the inside, with no chest incision at all. This approach is associated with shorter hospital stays, less time on a ventilator, and lower rates of intensive care admission compared to surgical ligation.
The main limitation is size. The closure devices have retention discs that can be too large for the tiniest babies. In an infant weighing 1,000 grams, the left pulmonary artery is only about 3 millimeters wide, and some device discs measure over 5 millimeters. One specialized device now has FDA approval for premature babies weighing as little as 700 grams, which has expanded catheter-based closure to infants who previously would have required surgery. Still, surgical ligation remains the standard for many premature neonates when anatomy or weight makes catheter closure impractical.
Risks and Complications
The most well-known risk of PDA ligation is injury to the left recurrent laryngeal nerve, which sits close to the duct. Damage to this nerve causes vocal cord paralysis on one side. Reported rates in the general surgical literature range from less than 1% to about 9%, but in extremely low birth weight infants (under 1,000 grams), one study found the rate was as high as 67%. Babies with vocal cord paralysis after the procedure needed tube feeding for significantly longer, required more supplemental oxygen and ventilator support, and had considerably longer hospital stays.
Other potential complications include bleeding, infection, and chylothorax (leakage of lymphatic fluid into the chest). There is also a small chance the duct does not fully close or reopens after surgery, though the triple-closure technique using two suture ties and a clip is designed to minimize this.
Recovery After the Procedure
Recovery depends heavily on the baby’s size and overall condition. For premature infants who were already in the NICU on ventilators, surgical ligation tends to involve longer postoperative and total hospital stays compared to catheter-based closure. The surgery itself addresses the PDA, but these babies often remain hospitalized for weeks or months for prematurity-related care that has nothing to do with the ligation.
Babies who undergo catheter-based closure generally wean off ventilators faster, tolerate feeding sooner, and gain weight more quickly. For full-term or older infants with an isolated PDA and no other health issues, the recovery timeline is considerably shorter, and most do well without long-term heart-related problems once the duct is closed.