Learning that their child has been born with a heart defect is devastating news for parents and for good reason. Some congenital heart defects can be fatal though many, including heart valve abnormalities, can be successfully repaired. The surgical ‘fix’ usually involves replacing a faulty natural valve with a mechanical one or a valve fashioned from animal tissue. However, replacing heart valves is a particular challenge in children because as they grow, so do their hearts. Over the years, additional surgeries are needed to replace smaller artificial valves with larger ones of appropriate size.
Now a team led by Dr. Steven Bibevski, a pediatric heart surgeon at Joe DiMaggio Children’s Hospital in Hollywood, Florida, is pioneering the use of a material called extracellular matrix (ECM) to create long-lasting, perhaps lifelong replacement heart valves for children.
“The issue is that children have a lot of growth to do and the current technology that is out there for valve replacement is based on solutions that work for adults,” said Dr. Bibevski. Today’s valves cannot accommodate a child’s growth. A youngster can therefore anticipate multiple surgeries to replace heart valves that do not grow as they do.
There are additional issues with current artificial valve technology. Tissue valves, derived from humans, pigs or cows, are problematic because they contain cellular elements that can trigger the body’s immune response, leading to valve failure. Mechanical valves, made from materials such as carbon and titanium, require a child to take blood thinner medication to prevent the formation of blood clots.
The ECM used by Dr. Bibevski is a material derived from cow intestinal tissue that has the cells removed from it to create a kind of scaffolding that permits human cells to grow on it once placed in the body. Removal of the cells from the tissue before placement in humans theoretically makes it less likely to trigger the body’s immune response. This can help to increase the length of time that a surgically replaced valve works properly.
The ECM valve is like natural tissue, so it does not promote clot formation, eliminating the need for blood thinners. Dr. Bibevski handcrafts valves from ECM by shaping them into a cylinder then folding the edges back on themselves to create multiple layers. These layers can promote valve strength and prevent tearing.
Once installed, the valve resembles a folded paper ‘Cootie Catcher,’ the homemade paper toy. The valve opens and closes with the natural beating of the heart, just like the origami counterpart would open and close. The ECM is custom made for each patient. Because the ECM valve is the correct size for the child, it can result in optimal function.
The patient’s own cells can also grow on the ECM valve. According to Dr. Bibevski, “a very promising ingrowth of the human tissue” can occur on ECM, and it therefore “has the potential to become living tissue.” If that happens, the valve becomes living tissue and can grow with the child. This growth could result in continued proper valve function. It may even eliminate the need for future valve replacement surgeries altogether.
Dr. Bibevski highlighted one of his young patients whose life-saving ECM mitral valve replacement was done five years ago. She is not expected to require another heart valve surgery anytime soon because her valve is growing with her and functioning
With further development, ECM valves may one day become the standard of care for children with heart valve defects, one that offers a ‘one and done’ surgery and a higher quality of life.
- Thanks to the marvel of modern medicine, heart valve abnormalities can often be successfully repaired.
- However, replacing heart valves is a particular challenge in children because as they grow, so do their hearts.
- To address this significant problem, a team of researchers is working to create long-lasting, perhaps lifelong, replacement heart valves for children.
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- Donald Schwartz joined Merck & Co., Inc. as a manager of global marketing communications, rising to his current role as an executive director of Merial’s US Business Operations with responsibilities for business development, market research, regulatory, customer care, veterinary technical solutions, public affairs, communications and business analytical functions. Don has also been the head of a successful advertising and communications agency specializing in pharmaceutical and technical products.
Steve Bibevski, M.D, Ph.D. is a pediatric cardiothoracic surgeon at Joe DiMaggio Children’s Hospital in Hollywood, Florida. He is also a researcher affiliated with Florida International University’s Department of Bioengineering. Dr. Bibevski performs surgery on children with various forms of congenital heart disease and one area of his research involves surgery on heart valves in children.