WASHINGTON—Researchers have discovered what they call a previously unrecognized way that degradation can occur in silicone-urethane materials, often used in medical devices.
The study, published in the American Chemistry Society's journal Macromolecules, could have implications for device manufacturers considering use of these materials in the design of some implantable devices, including cardiac defibrillation leads, the ACS said.
The researchers said some implanted biomedical devices, such as pacemakers and defibrillators, have parts made of polyurethane and silicone. While these materials have been extensively studied for failure resulting from interaction with oxygen, no published study has looked at interaction with water as a potential failure mechanism in this class of materials, the ACS said.
In a cardiac lead application, these materials may be used as a coating on the electrical wires that carry electric current from the battery in the device to the heart. Surgeons implant pacemakers in 600,000 people worldwide and defibrillators in 100 000 people in the U.S. each year, the ACS said. Since these implants must function reliably for years, the scientists wanted to determine whether the silicone-urethane material is suitable for long-term implants.
ACS said laboratory tests, including accelerated aging of the materials under conditions that simulated the inside of the human body, found indications the material begins to break down within three to six years.
"By making the conclusions of this novel, scientific research public in a respected peer-reviewed journal, device manufacturers may now consider these important findings in their device designs," said Kimberley Chaffin, lead author of the report.