Nitinol heart valve for children

Researchers at the UCLA Henry Samueli School of Engineering and Applied Science and paediatric cardiologists at Mattel Children’s Hospital at UCLA have collaborated to develop new heart valves and stents made of a super-elastic, shape-memory metal alloy called ‘thin film nitinol’.

The collapsible heart valve for children can be loaded into a catheter, inserted into a vein in the groin area, guided into place and then deployed in a precise location within the heart. As the valve is released from the catheter, it springs back to its original shape and begins to function.

Using these means children with congenital heart defects may soon have an alternative to invasive open heart surgery that will mean less time in the hospital, a quicker recovery and no need to break the breastbone.

“What is really novel about the valve UCLA Engineering has created is the memory retaining alloy and butterfly design that opens or hinges from the middle of the valve rather than the edges,” says UCLA mechanical and aerospace engineering professor Gregory Carman, who, along with UCLA researcher Lenka Stepan, crafted the valve. “The unobtrusive leaflets within the valve mean there is no obstruction to blood flow. This smaller, low-profile design is well suited for children and, over time, will potentially allow children born with heart valve defects to experience less pain and live much fuller lives.”

Dr. Daniel Levi, assistant professor of paediatric cardiology at Mattel Children’s Hospital at UCLA, designed the valve and joined Carman and Stepan to create and develop the revolutionary new device.

“Using catheters and collapsible valves, heart valves can be replaced without stopping the heart, without cutting the chest open and without long recovery times,” says Levi. “This will represent a huge improvement in care for children living with a very difficult condition.”

Heart valves have a limited life span, and as children grow they often need three or four valve replacement operations before adolescence. Open-heart surgery typically requires three to four days in intensive care, at least one or two weeks in the hospital and a lengthy recovery period at home. In contrast, patients who have valves replaced via catheter could go home as early as the following day, with little pain.

Small children have to date been unable to benefit from catheter-based valve replacement as most of these valves are bulky and can be used only in adults. Thin film nitinol could allow doctors at UCLA to make a transcatheter heart valve suitable for use even in small children.

“By collaborating with UCLA Engineering, we are creating a paediatric heart valve that has great strength and biocompatibility. It could mean a shortened procedure, a lower level of risk, and much less stress on the patient and their family. It also will mean a lower cost to the health care system,” Levi says. “Our valve is presently being designed for replacement of the pulmonary valve, but eventually may also be able to be used for the aortic valve.”

The UCLA team also has used thin film nitinol successfully in other biomedical applications such as stents and other implantable biomedical devices.

“Recent studies we’ve conducted have shown that thin film nitinol can be used to cover stents and to provide a barrier in preventing regrowth of tissue into stented arteries and veins. Beyond its use in either percutaneously or surgically placed valves, I anticipate that thin film nitinol will have a wide variety of applications in the development of future implantable biomedical devices for both adults and children,” Levi says.

The researchers are hoping to collaborate with industry to bring the valves to market, but it will be a number of years before the valves will be commercially available.

UCLA Engineering professor Gregory Carman (right) and Dr. Daniel Levi of UCLA’s Mattel Children’s Hospital (left) are using a super-elastic, shape-memory metal alloy called thin film nitinol to develop a collapsible heart