Published August 25, 2015
Journal of the American College of Cardiology

When small children need heart valve replacements, they often require multiple operations because the artificial valves they receive cannot grow. Soon, there may be a solution to this challenge.

A study led by Farhan Zafar, MD, and David Morales, MD, director of Congenital Heart Surgery, Heart Institute, reports early success in animal models with a new heart valve that actually does grow.

The study team evaluated a tricuspid valve made of small intestinal submucosa-derived extracellular matrix (SIS-ECM). Results appeared Aug. 25, 2015, in the Journal of the American College of Cardiology.

This special tissue, made by Georgia-based CorMatrix Cardiovascular, has been used as a patch in various tissue repairs. This was one of its first uses as a replacement valve.

Surgeons placed the new valves in eight lambs, then evaluated outcomes three months and eight months later.

On average, the lambs tripled their weight while their replaced heart valves grew 50 percent in diameter. This expansion was similar to natural growth. Valves in seven animals functioned normally, one developed a malfunction.

The study indicates that the valves grew as resident mesenchymal cells migrated into the bio-scaffold.

The valves functioned without inflammation or calcification. They also outperformed standard prosthetic valves placed in other lambs, which showed signs of stenosis.

“This growth characteristic is vital for pediatric patients,” Morales says. “Many surgeons implant oversized valves in an attempt to accommodate for this problem. However, patient-to-valve size mismatch often leads to its own complications.”

Some young adults already have received SIS-ECM valves on a “compassionate use” basis, and early outcomes have been promising. This clinical use and the research here led to the U.S. Food and Drug Administration approving an IDE clinical trial in children and adults. Cincinnati Children’s is the first to enroll a pediatric patient in the study.