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Making Strides in Treating the Smallest Heart Patients

"I think tens of thousands of babies have been saved by this," says Dr. Evan Zahn, professor of Cardiology, director of the Guerin Family Congenital Heart Program, and director of the Division of Pediatric Cardiology at Cedars-Sinai Guerin Children’s and the Smidt Heart Institute.

Dr. Zahn—a preeminent expert in pediatric cardiology and congenital heart disease—is referring to a game-changing treatment for the tiniest of cardiology patients. These babies entered the world well ahead of schedule, often weighing two pounds or less and having a common but potentially fatal opening between the aorta and the pulmonary artery in their hearts. 

The patent ductus arteriosus (PDA) opening naturally closes in most babies shortly after birth. If the opening doesn’t close, it can lead to complications such as lung disease, heart failure, brain hemorrhages and even death.

These tiny patients owe their survival to an innovative device known as the Abbot Amplatzer Piccolo Occluder and a pioneering procedure developed by Dr. Zahn and his team to implant the device. The U.S. Food and Drug Administration approved the Piccolo Occluder in January 2019, making it the world’s first minimally invasive closure device specifically designed for premature babies and newborns to correct PDA without the need for open-heart surgery.

We sat down with Dr. Zahn to discuss the recent advances in mending miniature hearts.

Pediatric cardiology has evolved exponentially since you entered the field more than three decades ago. What do you consider to be the most significant milestones?

Dr. Evan Zahn: The dramatically increased survival rate for babies born with congenital heart disease, which is now upwards of 97%. Up until 1990, the survival rate was about 85%. This field has advanced to the point that the expectation is not just survival, but long-term survival and enhanced quality of life.

What do you mean by long-term survival?

EZ: There are now more adults who were once children with congenital heart disease than there are children being born with congenital heart disease. Roughly 40,000 babies are born with congenital heart defects per year in the United States, and—because long-term survival is so high—there are over 1.5 million adults who entered the world with a congenital heart defect. 

Is there a milestone that’s meaningful to you personally?

EZ: Yes, this is a milestone that is my passion: I’ve been fortunate enough to play a direct role in minimizing the therapeutic trauma that babies and children with congenital heart disease have had to historically go through to survive, such as having repeated open-heart surgeries. Many procedures can now be done with minimally invasive catheter techniques, which is good for babies, children and adults with congenital heart disease and their families. 

You’ve played a pioneering role in developing minimally invasive catheter procedures, starting with the Piccolo Occluder. How did that unfold?

EZ: The contribution by our Cedars-Sinai team is monumental. We didn’t design the Piccolo Occluder, but about 10 years ago we developed a nonsurgical catheter-based procedure to implant the device in premature infants by guiding a catheter through a vein in the baby’s leg to the heart, where the device—which is smaller than a pea—can be deployed in a matter of minutes to close the PDA. 

We did the first-ever three Piccolo implants in premature babies. Those procedures were remarkably successful, and I went on to serve as the principal investigator, and Cedars-Sinai served as the coordinating center, for a multisite Piccolo Occluder clinical trial. That was four years ago, and I can confidently say that this device and the transcatheter procedure we developed have revolutionized pediatric cardiology and neonatology worldwide.

Are you still involved in Piccolo Occluder research?

EZ: Yes, our Cedars-Sinai team is participating in a national, five-year clinical trial funded by the National Institutes of Health. The study’s aim is to determine the long-term effects on patient outcomes of implanting the Piccolo Occluder to treat PDA in premature babies. 

We know this device successfully treats PDA, but these severely premature babies have many other problems, such as lung issues and developmental delays, and we hypothesize that by treating PDA early and effectively, these other problems also benefit. The study’s findings will inform if this treatment approach is the best practice in the clinical care of PDA in preterm infants and if it provides other benefits. We will start enrolling participants this spring.

Have you been involved with other devices for treating babies and children born with congenital heart defects?

EZ: Some congenital heart defects involve one or more narrowed blood vessels that require the insertion of stents, which are metal mesh tubes that allow blood to flow. Stents are made for adults, so for many years we’ve been retrofitting adult stents to fit into tiny blood vessels. 

Stents have a fixed diameter, and as children grow, they need open-heart surgery to replace stents that have become too small. Creating a stent that could be inserted into a tiny baby’s narrowed pulmonary artery or aorta and remain there through adulthood has been pediatric cardiology’s holy grail. 

Are you still searching for that holy grail?

EZ: For the past four years, I’ve been working with two brilliant engineers who founded Renata Medical, where I serve as medical director, and have provided input for the Minima Stent, which is designed to grow with the child into adulthood without ever needing to be replaced. This is immeasurably better than having to remove and replace stents through risky surgeries at multiple points during the patient’s physical development. 

We conducted an early feasibility study last year where we implanted the stent through a minimally invasive procedure in 10 babies around the country, including at Cedars-Sinai; all cases have gone well. Now we’re enrolling more babies for a larger, multisite clinical trial. I help train teams at the participating sites on how to implant the stent.

What’s the outlook for this innovative stent?

EZ: If the Minima Stent continues to perform as well as it has, it’s possible that by late 2024 or early 2025 it will be the world’s first stent approved for newborns, infants and toddlers. The most rewarding part is that as these children grow, the stent can be easily enlarged to keep pace with their growth, and there’s no need for open-heart surgery to insert a replacement. I’m just so excited about that.

To learn more about this or other Smidt Heart Institute research, email