Dr. Mark Rodefeld, a pediatric heart surgeon at Indiana University, has spent decades helping to fix children’s hearts. He found one problem particularly vexing, leading to years of his own research before reaching out to NASA Glenn Research Center to help him solve it.
“About 1,500 children are born every year with a missing ventricle,” Rodefeld says. “The numbers sound low, but it’s actually the fifth most common problem in those with heart issues.” By having half a heart essentially, the body is missing half of its pumping ability to oxygenate blood and circulate it to stay alive. Currently, the best solution is a heart transplant, however, transplantation with a donor heart is a limited option due to donor availability and short-term success, he explains.
The next best solution, and the one most commonly used with patients, is a partial fix called the Fontan procedure. This requires three open-heart surgeries to create a passive circulation network to replace the blood pumping function of the missing ventricle. As with any pediatric surgery, the risk of multiple surgeries increases the chance of problems, like infection, medication reactions, and surgical or follow-up errors.
“The children survive, but eventually, inefficiency in circulation due to the low pumping pressure catches up with them in their early adulthood when the remaining part of the heart gets worn out from doing all the work,” he says.
A Better Method
Rodefeld’s idea was to insert a small conical pump, driven by an electrical motor, into an existing Fontan network. This pump would reproduce the pressures and flow coming from the body and head, reducing the wear and tear on the single remaining ventricle and, in doing so, extend the life of the patient.
“I knew I wanted to put a bi-conical motor into the cross section of the network, but I needed experts in flywheel technology at NASA Glenn to design and scale it to size,” Rodefeld explains. A team of engineers at Glenn spent two years designing, building, and testing a bi-conical heart pump for Rodefeld. Eventually they completed a functional prototype of the bi-conical heart pump to allow for traditional motor operation as well as levitation operation. (See Figure 1)
“Unlike conventional motors, the outside rotor of this pump spins around the inside, which allows for complex fluid pump shapes to be created on the surface of the rotor,” says NASA Glenn’s David Avanesian, a systems engineer and project manager. “Those shapes then ‘grab’ blood coming from the body and head, mix it, and then direct it to lungs for oxygenation using the von Karman effect for asymmetrical flow pattern.”
The Glenn team’s extensive design, build, and testing led to successful results proving the feasibility of Rodefeld’s original idea. And while the size of the motor has been scaled down significantly, engineers are working toward making it even smaller to fit into the Fontan circulation architecture.
Further development is planned to scale the motor down to its required diameter, about the size of a nickel. Over the next few years Rodefeld hopes to work with Glenn engineers in additional development and testing with the goal of advancing this technology in young patients.
For more information, visit www.nasa.gov .