Quantification and Characterization of Particulate Matter in Polyurethane Shape Memory Foams and Foam-Based Devices

Abstract

Endovascular therapy involves the placement of an implantable filler coil directly into an aneurysm sac to occlude the space and promote healing of the damaged vessel wall. Implantable devices must be tested to assess and address all potential risks that they may pose. Shape memory polymer (SMP) foams have been placed over nitinol coils as an endovascular treatment option for cerebral aneurysms. These foams have large potential for use in aneurysm embolization, but it is unknown whether they will generate harmful particulate matter upon implantation into the body. Particulates could be the result of damaged or weakened foam struts that are prone to fracture upon agitation or external forces. Currently, there are no existing protocols for the quantification of particulate matter in SMP embolic devices. The focus of this work was to investigate particulate levels in SMP foams and foam devices.

Protocols were developed to quantify particulate formation in a foam cleaning process, two reticulation processes, and device delivery. Furthermore, visual characterization and cytocompatibility testing was performed on SMP foam particulates. Results from the studies demonstrated that the foams and foam-based devices generate particulate levels that are in compliance with limits stated by the most relevant standard. When concentrated particulate treatments were administered to fibroblasts, they exhibited high cell viability (100%). These results provide further validation of the use of SMP materials in a neurovascular embolization device.