_MEDICINE Pediatric Surgery

_Patched Up Hearts

Motivated by the delicacy of infant heart surgery, an interdisciplinary team patented an internal patch that makes repeat operations safer and faster. 

_Randy Stevens

Stevens is a pediatric cardiothoracic surgeon at the College of Medicine.

_Amy Throckmorton

Throckmorton is an associate professor and director of the BioCirc Research Laboratory in the School of Biomedical Engineering, Science and Health Systems.

The natural hazards of performing open-heart surgery multiply when the patient needs repeat operations, as when an infant is born with congenital defects.

“Scar tissue is the enemy,” says College of Medicine Assistant Professor Randy Stevens, noting that tissue that develops during the healing process can nearly fuse the heart with the sternum itself. Complicating matters further is the fact that the pericardium — a sac protecting the heart — must be opened during an initial cardiac surgery, leaving the organ vulnerable to any slip of the knife.

This rudimentary diagram forms the basis of the patent for Randy Stevens’ pediatric surgical patch.

As a pediatric cardiothoracic surgeon, Stevens hoped to make re-sternotomies easier for surgeons and safer for patients. He was also aware that colleagues performing the procedure on adults sometimes opt for inserting a stent through a groin, which is less risky but may have a short-lived payoff.

The prototype includes accordion pleats and tubes that can be used to guide surgical tools.

He envisioned a patch that could protect the pericardium and incorporate a built-in guidance track that would help steer the surgical tools his peers use during re-sternotomies.

A fold in the material of the patch allows it to expand as a child’s chest grows. Stevens’ preliminary design made from napkins and drinking straws guided later prototypes.

Using paper napkins and plastic drinking straws, he fashioned a rudimentary model in the shape of a butterfly. He deliberately included a fold in the napkin, to accommodate organ growth. This is a critical step, since neonates with severe congenital conditions such as tetralogy of Fallot with pulmonary atresia — the condition with which comedian Jimmy Kimmel’s son was born — are likely to need multiple surgeries.

The patch remains inside the patient’s chest cavity for protection after each surgery, allowing any future surgery to be performed with a built-in tool kit. Because the butterfly patch gets attached to the sternum, it provides an enduring layer of protection between the knife and the heart.

Tubes incorporated into the patch form channels into which attachments for a saw ease and speed the surgical process. This is vitally important, since time is of the essence during open-heart surgery.  

To craft a workable design from his sketches, Stevens turned to Amy Throckmorton, professor of biomedical engineering and director of the BioCirc Research Laboratory in the School of Biomedical Engineering, Science and Health Systems. Having dedicated her career to devising new therapeutic strategies for pediatric patients, Throckmorton has gained extensive know-how in designing and patenting cardiovascular pumps and other medical devices.

Throckmorton invited undergraduate design students Youssef Jouichate, Rahul Akkem, Felix Agbavor, Shamayel Alroomi and Daniel Graciano to design, build and test a prototype of the butterfly patch that includes accordion pleats and tubes that can be used to guide surgical tools.

After patenting the design in December 2021, the team is leveraging Drexel’s Coulter-Drexel Translational Research Partnership to steer the butterfly patch toward commercialization. The group engaged a market research consultancy that conferred with 10 cardiac surgical specialists who agreed the need is great among pediatric patients. Next step: Attract a company interested in manufacturing the patch and revolutionizing re-sternotomy procedures for pediatric patients.