Early Success for Replacement Valves That Can Grow With a Child

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.

Fig A:  In graph lambs tripled their weight over the study period with a corresponding, appropriate increase in a tubular tri-cuspid valve made from small intestinal submucosa-derived extracellular matrix (SIS-ECM).
Click image to view caption.
Fig B:  : Visual examination indicated that SIS-ECM valves appeared similar to native valves (NV). This valve displays signs of chord formation, tendons that connect the valve to heart muscle.
Click image to view caption.

Citation

Zafar F, Hinton RB, Moore RA, Baker RS, Bryant R, 3rd, Narmoneva DA, Taylor MD, Morales DL. Physiological Growth, Remodeling Potential, and Preserved Function of a Novel Bioprosthetic Tricuspid Valve: Tubular Bioprosthesis Made of Small Intestinal Submucosa-Derived Extracellular Matrix. J Am Coll Cardiol. 2015 Aug 25;66(8):877-88.

Farhan Zafar, MD

David Morales, MD

David Morales, MD