Children with congenital heart disease (CHD) often receive small cardiac stents that are not designed to expand to the size of large adult blood vessels. However, that is now set to change with a new cardiac stent that is designed to be implanted in small diameter blood vessels in infants and small children and can be gradually expanded up to adult size over the course of the child’s lifetime through a series of minimally invasive procedures.

Children’s Hospital Los Angeles (Los Angeles, CA, USA) has become the first in the world to implant Renata Medical’s (Costa Mesa, CA, USA) Renata Minima Stent, a cardiac stent designed specifically for babies and young children that can be expanded all the way to adult size. The first-in-human procedure is part of a multicenter early feasibility study that aims to solve a longstanding limitation of traditional cardiac stents: They’re too large to be used in the youngest and smallest patients.

The first recipient of the Renata Minima Stent is a five-month-old boy who was born with two complex congenital heart defects: dextro-transposition of the great arteries (D-TGA) - a condition where the two main arteries carrying blood out of the heart are switched in position - and coarctation (narrowing) of the aorta, which carries blood flow to the body. The investigational expandable Renata Minima Stent offered an appealing option. The stent is designed for neonates, infants and young children who have blockages or narrowing in the aorta or pulmonary artery. In a pioneering procedure, the team of physicians inserted a catheter—a thin, flexible tube—into an artery in the baby’s leg. Guided by an X-ray monitor, they then carefully threaded it through the artery and across the area of narrowing. The physicians used the Renata Minima Stent that comes pre-mounted and crimped onto a balloon inside the delivery catheter. The company’s engineers worked to miniaturize this technology to accommodate the cardiac needs in pediatric patients. When the catheter reached the narrowed aorta, the team inflated the balloon, expanding the stent across the area to prop open the artery. The balloon was then deflated and removed, along with the catheter, while the stent remained securely in place.

A key innovation of the Renata Minima Stent is that the stent can be expanded to fit a child’s growing blood vessels. As the child grows, the team can expand the stent all the way up to adult sizes - more than 18 millimeters wide. The physicians anticipate that patients who receive the stent as babies will likely need to have it expanded two to four times over their life. The adjustments will be done through minimally invasive catheter procedures. The multicenter early feasibility study, officially known as the Multicenter Early Feasibility Trial of Neonatal, Infant, and Young Child Vascular Stenoses Studying the Renata Minima Stent, is taking place at four centers around the US. The goal is to enroll a total of 10 patients across the four sites over the next few months. The US Food and Drug Administration will then review the safety and efficacy data from those first 10 patients. If the results are positive, then the next step will be a larger trial involving more patients and centers.

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