Abstract
Conventional endovascular embolization of intracranial (or brain) aneurysms using helical detachable platinum coils can be time-consuming and occasionally requires retreatment due to incomplete coil packing. These shortcomings create a need for new biomedical devices and methods of achieving brain aneurysm occlusion. This paper presents a biocompatible and highly porous shape memory polymer (SMP) material with potential applications in the development of novel endovascular devices for treating complex intracranial aneurysms. The novel highly porous polyurethane SMP is synthesized as an open cell foam material with a glass transition temperature (Tg) of 39 °C using a sugar particle leaching method. Once heated above the Tg, the compressed SMP foam is able to quickly return to its original shape. An electrical resistance heating method is also employed to demonstrate a potential triggering design for the shape recovery process in future medical applications. The mechanical properties of the developed SMP foam are characterized at temperatures up to 10 °C above the respective Tg. The results from this work demonstrate that the porous SMP material developed in this study and the electrical resistance heating trigger mechanism provide a solid foundation for future design of biomedical devices to enhance the long-term therapeutic outcomes of endovascular intracranial aneurysm treatments.
Highlights
Polymeric materials with suitable thermo-mechanical properties and functionality, such as biocompatibility, biodegradability, oxidative resistance and shape memory/recovery, are clinically desirable for biomedical applications
shape memory polymer (SMP) materials could present an alternative approach to Guglielmi detachable coils (GDCs)-based endovascular coil embolization, since their unique shape recovery property allows for a similar style of deployment and occlusion
The fully cured SMP samples were removed from the molds, sealed in vacuum bags, and stored in a vacuum desiccator (Bel-Art Lab, SP Scienceware, Wayne, NJ, USA) to ensure no moisture contamination occurred before subsequent thermomechanical characterization experiments [48]
Summary
Polymeric materials with suitable thermo-mechanical properties and functionality, such as biocompatibility, biodegradability, oxidative resistance and shape memory/recovery, are clinically desirable for biomedical applications. SMP materials could present an alternative approach to GDC-based endovascular coil embolization, since their unique shape recovery property allows for a similar style of deployment and occlusion. An open-cell porous polyurethane SMP material referred to as Cold-Hibernated Elastic Memory (CHEM) foam has been investigated for the fabrication of aneurysm occlusion devices. Metcalfe et al reported a series of experimental investigations and an animal study using SMP foams for aneurysm treatment [41]. Low-density aliphatic polyurethane SMP foams manufactured with a chemical blowing process have been used to create uniformly-shaped embolization plugs, which demonstrated stable thrombus formation and complete endothelialization of the aneurysm neck within. We demonstrate a potential deployment method using a group of resistively heated carbon fiber filaments within compressed SMP foam to raise its temperature and activate shape recovery
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