Chronic lung disease (CLD) of prematurity afflicts over 40% of the increasingly premature infant population born prior to 28 weeks gestation. It is commonly characterized by the need for diuretics and respiratory support precluding discharge home.
Recent work at UVA Children’s Heart Center demonstrated that more than one-third of these fragile patients also have an atrial septal defect (ASD), patent ductus arteriosus (PDA), or both, which significantly worsen their lung disease severity. Surgical closure of these lesions in this population has been associated with significant morbidity, and medical treatment is commonly ineffective and dangerous. However, UVA Children’s Heart Center team is proving that transcatheter occlusion is not only possible in this tiny patient population, but the best option for some.
Making a Case for Transcatheter Occlusion
A growing body of evidence demonstrates that premature infants with CLD of prematurity and ASD or PDA experience significant clinical improvements following transcatheter occlusion of their lesions. The UVA Children’s team has taken this research a step further, conducting a case-controlled, retrospective study of their own experience, while also launching a program to incorporate their findings into practice.
“Our study results and the clinical experiences of the POLeR [Percutaneous Occlusion of Left-to-Right] shunts program influenced each other. We saw significant clinical improvements in premature infants with chronic lung disease following device closure of residual connections of holes inside the heart [ASD] and outside the heart [PDA],” says pediatric cardiologist Michael McCulloch, MD.
He further explains, “A few papers had been published on these results from other institutions. Yet none of them compared the patients who had their defects closed with those who didn’t. There was never a control population in these papers.”
The research team assessed outcomes of all premature infants at UVA Children's diagnosed with CLD of prematurity at 36 weeks. “We reviewed our experienced outcomes over 5 years, but also included a control group. We were able to demonstrate a significantly reduced need for supplemental respiratory support — ventilator, CPAP, high-flow nasal cannula — in those infants who underwent this procedure compared to those who did not,” says pediatric cardiologist and fellow Firezer Haregu, MD.
Percutaneous Occlusion of Left-to-Right Shunts Program Takes Shape
With these and other study findings as a framework, the UVA Children’s Heart Center team built the POLeR Program to optimize care for premature infants with both CLD of prematurity and PDA or ASD. They answer key questions to guide care for this fragile population.
Which Patients Are the Best Candidates for Interventional Closure?
According to pediatric interventional cardiologist Michael Hainstock, MD, the ideal patient for transcatheter occlusion in the cardiac catheterization lab is the premature infant with all of the following:
- ASD or PDA
- Chronic lung disease of prematurity requiring long-term, lifesaving therapies (mechanical ventilation, prolonged oxygen therapy)
- A need for respiratory support at a level that precludes them from going home
Hainstock adds, “Premature neonates at 3 to 5 weeks of life with a very low birthweight and moderate to large hemodynamically significant PDA would also benefit from closure prior to the development of bronchopulmonary dysplasia.”
What Are the Advantages of This Approach Compared to Common Treatments for ASD and PDA?
Transcatheter occlusion is more effective and lower risk compared to alternative approaches to treating these lesions, which include:
- High-dose diuretics, which are typically inadequate and often associated with significant electrolyte abnormalities and osteopenia
- Medications such as acetaminophen or ibuprofen, which are 50-60% effective at closing a PDA, but can be associated with bleeding into the brain and injuries to the intestinal tract
- Surgical closure, which is significantly more challenging in patients of this size and gestation age due to the significant potential for worsening lung injury and chest deformities
How and When Should Infants Be Referred to UVA Children’s for Surgery?
If an infant meets the parameters outlined above, McCulloch suggests that cardiologists or neonatologists reach out to his team for consultation. “If the POLeR team agrees the patient would likely benefit from intervention, we will make arrangements for transfer as soon as possible,” he says.
Once the procedure is completed, the infant will stay in the UVA NICU between 1 to 3 days. They will then be transferred back to their home institution. “We work very closely with the referring physicians and institutions to ensure we can get these babies back to their primary team and closer to home as soon as possible,” says McCulloch.
How Is Transcatheter Occlusion Performed?
This procedure varies slightly depending on the type of closure, Hainstock explains. During PDA closure:
- A catheter is inserted in the femoral vein and advanced through the right side of the heart collecting oxygen and pressure information.
- The catheter is advanced across the PDA and an angiogram is taken to determine the size and shape of the PDA.
- Using measurements from both the angiogram and intraprocedural echocardiography, an appropriately sized occlusion device is inserted through the catheter and delivered into the PDA.
- Once the device is positioned, the echocardiogram ensures no obstruction to the aorta or the pulmonary artery.
- The device is released from the delivery system with the echocardiogram again demonstrating the device in appropriate position with no obstruction to pulmonary or systemic arteries.
- The catheter is removed from the femoral vein with a small bandage applied overnight.
A successful ASD closure is a very similar procedure, with the following steps:
- A catheter is inserted into the femoral vein and advanced through the right side of the heart, crossing the atrial septal defect into the left atrium.
- Intraprocedural echocardiography is used to measure the size of the ASD and determine if there is adequate tissue for a device to be placed.
- Once this is ensured, an appropriately sized ASD device is chosen and advanced by deploying first the left atrial disc followed by the right atrial disc, effectively occluding the defect.
- Once the device is in an optimal position, it is released from the delivery system with the echocardiogram again confirming a safe and effective position of the device.
- The catheter is then removed with a small bandage applied overnight.
Providing Complex Care to Tiny Patients Takes Team Approach
A dedicated team of specialists working together every step of the way is key to evaluating the needs of each individual patient and providing the level of care necessary for medically fragile neonates. In addition to the physicians mentioned, the POLeR team includes neonatologist Brooke Vergales, MD, pediatric pulmonologist Andrea Garrod, MD, and others specially trained to care for this patient population.
“This process requires the clinical expertise of the full POLeR team to select the right patients for intervention, and the technical expertise of our cardiac catheterization team and dedicated pediatric cardiac anesthesiologists to perform it safely and effectively,” says McCulloch.
He adds, “It also takes the solid infrastructure UVA Children’s provides to do everything from transporting the baby safely to and from their home institution, caring for them while they are at UVA, and keeping families and their primary care team informed of the baby’s status throughout the process. We consider ourselves incredibly fortunate to have been able to form such a dedicated, skilled, and capable team who genuinely share the central focus of improving the lives of these fragile children.”