The Food and Drug Administration has approved the use of a medical device in humans for deliberately blocking blood flow to treat bleeding abnormalities or other conditions, a procedure known as embolization. The device integrates expanding shape memory polymer technology that was partly developed at Lawrence Livermore National Laboratory (LLNL).

LLNL scientist Duncan Maitland, with clearance for its IMPEDE embolization plug, designed to block or reduce blood flow in the peripheral vasculature. The device can be "programmed" into a particular shape, made thin enough to fit in a catheter and expand to its former shape when exposed to stress or heat.

Approval clears major hurdle for shape memory devices

Researchers said the device has immense potential to replace current embolization technology, which generally employs metal coils that occasionally tear through walls of the blood vessels and lead to further complications such as hemorrhaging.

Shape memory foams can be made thin enough to be inserted into blood vessels and arteries, and once in place, expand either on a time-release basis or when heated by the blood to seal up vessels and arteries and allow for healing tissue to develop.

"It's an entry point for the technology," said LLNL staff researcher Thomas Wilson. "This (FDA approval) is a tremendous hurdle, and what's been achieved will open the doors to other shape memory devices. This is the baby step. It's a huge satisfaction to actually see this come to fruition and see it help people."

Under a cooperative research and development agreement (CRADA) with the Lab, development of the devices continued at Texas A&M. Maitland founded his company as Shape Memory Therapeutics Inc. and completed animal testing to support application in humans. The company changed its name and is headquartered in Santa Clara, California.

'Decades' of development at LLNL

Because the polymer materials used in the foam are low density and don't absorb X-rays, Rodriguez worked on ensuring the devices would show up in medical imaging and engineered the foam material with channels so blood could pass through them and allow the body to begin the healing process.

"It's taken decades to get where they are, from developing the polymers to designing devices to creating the devices," Rodriguez said. "It's rewarding to have worked on something that now has the potential to help somebody and advance health care."

LLNL engineer Ward Small began working on the materials in 2003, fabricating catheter-based devices and discovering how to get them to actuate or expand under laser light. The biggest challenge, he said, was to achieve enough expansion and coming up with a way to detach it from its wire guide, deliver it precisely to the affected area and have it stay in place.

"The goal from the beginning was to actually see this come to fruition," Small said. "We were hopeful, but it took a long time. It's awesome that something that started here is on its way."