Making a lifesaving operation even safer

It is one of modern medicine’s great advances — the ability of surgeons to repair congenital heart defects in very young patients.  Over the years, both surgical techniques and technology have improved so that these very sick kids are surviving and living long, productive lives.

Dr. Andrew Meyer wants to make that surgery even safer. Dr. Meyer, a pediatric critical care specialist who also is a biomedical engineer, is taking aim at a complication that can arise when some patients are hooked up to heart-lung bypass machines — the devices that make open heart surgery possible. In a small percentage of those patients, abnormal bleeding and clotting can occur.

That raises the risk of heart attack, stroke and other problems.

“I think the pumps we have are pretty good,” said Dr. Meyer, an assistant professor of pediatrics at UT Health San Antonio. “I don’t think we yet understand the patient’s response to the pumps. I want to know how I can treat that response with better drugs and better therapies to prevent complications. “

Dr. Meyer, whose research has involved analyzing blood samples from patients at University Hospital during bypass surgery, believes he has a pretty good idea of why the abnormal bleeding and clotting occurs. Now he’s looking at ways to correct the problem.

These machines do the work of the heart and lungs while surgery is underway, pumping blood throughout the body while adding oxygen to it. The process is similar to another lifesaving device called ECMO, or extracorporeal membrane oxygenation. ECMO allows a damaged or diseased heart and lungs to rest and recover while the machine takes over their duties for a time.

During the artificial pumping process, platelets — the blood cells that help form clots to stop bleeding — throw off tiny microparticles. While researchers have known about these microparticles for a while now, it’s only recently that the technology has been available to study them.

Dr. Meyer said these microparticles accelerate clotting by producing a substance called phosphatidylserine that binds the clot together. The faster the pumping, the more microparticles are produced.  When the machine turns the work of pumping back over to the heart, the microparticles gradually are cleared from the body.

Dr. Meyer — who also studies the phenomenon in adults in collaboration with researchers at the San Antonio Military Medical Center — will be looking next at potential therapies that might be used to prevent clotting by interfering with these microparticles.

He was one of seven researchers who received part of nearly $1.1 million in funding for congenital heart defect research recently from the American Heart Association and the Children’s Heart Foundation to continue his work.

Photo by Mark Greenberg Photography