Thermomechanical characterization of novel fiber-reinforced shape-memory polymer composite coils.

摘要

Aneurysms and Arteriovenous Malformations (AVM) are abnormalities of the vascular system that are medically considered to be amongst the most challenging disorders to both diagnose and treat[1]. An aneurysm is a weak area on the blood vessel wall that enlarges and further weakens with time. An AVM is a tortuous tangle of arteries and veins which are connected abnormally by one or more pathways called fistulas. Endovascular coil embolization is a minimally invasive procedure to treat aneurysms and vascular malfunctions by essentially occluding these pathways by means of a series of coils. A landmark paper[2] published in the Lancet in 2002 found that patients that underwent minimally invasive surgery for coil embolization to treat cranial aneurysms as opposed to open surgery had a dramatically better chance of surviving post-treatment with minimum disability. So compelling were the results that mid-way through the study, the steering committee found it unethical to subject the rest of the target population to any other method of treatment other than coil embolization. It changed the way aneurysms and malformations are being treated today. Though there have been a number of metal-based embolization coils available in the past few years, they have serious limitations, for example, in terms of their geometry and maneuverability through the tortuous vascular network to access the malformation.;Shape memory polymers are a class of materials that can be programmed to respond to specific stimuli in their environment. By using body temperature as a trigger, it is possible to deliver shape memory polymer-based coils in a minimally invasive manner to the target location where, on being exposed to body temperature they can 'switch' to their final shape. The purpose of this research is to baseline the thermomechanical characteristics of a shape memory polymer based composite system designed specifically for endovascular coiling. In doing so, we will be able to tailor our coils across a range of mechanical properties and geometries to provide optimum occlusion within the vast vascular network.