Commercial Translation of Shape Memory Polymer (Polyurethane) Foams for Vascular Occlusion Devices

Duncan J. Maitland, Ph.D.
Stewart & Stevenson Professor
Department of Biomedical Engineering
Texas A&M University

Abstract:  We have developed a shape memory polymer (SMP) foam embolic device for treating vascular applications including aneurysms, arteriovenous malformations and other indications requiring occlusion. The SMP implants include a passively actuated open-celled foam that expands radially from a compressed cylinder, which usually includes a central platinum-alloy coil. At implantation, the crimped foam expands, via water plasticization and thermal actuation, to create a high surface area, highly tortuous scaffold that also gently fills the entire target volume with a safe outward radial force. The surface area of the expanded foam is 100-1000 times greater than current devices. The pores of the SMP foam create small (100-1000 micron), interconnected channels that rapidly and completely clot. After implantation, the IMPEDE device also offers a porous morphology that acts as a scaffold for encouraging rapid long-term vessel healing by recruiting collagenous extracellular matrix.

We have concluded chronic animal studies with the SMP occlusion device in several species (e.g. pig, rabbit) at acute through 180 explant intervals. Implant response results will be presented from these studies. We have also conducted and published many biocompatibility, design verification, degradation, aging, sterilization and other tests of interest. These SMP materials are oxidatively degradable. The foams exhibit exceptional biocompatibility throughout each implantation period.

Three peripheral vascular occlusion devices (IMPEDE, IMPEDE-FX and RapidFill) have received regulatory clearances in Europe and/or the USA with pending submissions in multiple other countries. Applications include abdominal aortic aneurysm endoleaks, gastric and esophageal varices, blunt trauma, varicoceles, and arteriovenous malformations (AVMs). A neurovascular embolization foam-over-coil device, TrelliX, has also received CE Marking and is under application in the USA and elsewhere. Neurovascular applications include aneurysms and AVMs. In 2021, over 1000 patients have been treated with IMPEDE products and over 300 patients treated with TrelliX.

The University of Pittsburgh seminar will present the rational for pursuing embolic scaffolds, background material and device properties, benchtop and in vivo study results. Human case results will be highlighted. The devices and material technology presented is the result of over twenty years of effort by hundreds of engineers, scientists, students and staff. The commercial translation from academic ideation to patient treatment will also be highlighted.

Bio:  Dr. Maitland has worked as an engineer in aerospace, national defense and biomedical applications since 1985. His research projects include endovascular interventional devices, optical therapeutic devices and basic device-body interactions/physics including computational and experimental techniques. He has over 110 archival publications and 48 issued U.S. patents. His current focus is commercial translation of porous shape memory polymer medical devices. He is a fellow of the American Institute of Medical and Biological Engineering and the National Academy of Inventors.