Why shape memory polymer scaffolds

At the end of healing, fibrosis or fibrous encapsulation is the ideal response for an embolic device. The process begins with injury to the tissue and implantation of the material. Thrombi, or blood clots, begin to form immediately based on the processes previously described, over the course of minutes to hours. This is enhanced by changes in blood flow patterns, permeability of blood vessels, and composition 

In preliminary animal studies that sought to treat surgically induced carotid side-wall aneurysms in a porcine model, polyurethane SMP scaffolds proved to be highly advantageous materials to create long-term, stable occlusion without recanalization (Rodriguez et al., 2014). The histology performed in this study 90 days postimplantation 

The organized collagen shown throughout the entire volume of the SMP scaffold and the neointimal layer across the aneurysm neck both support the notion that vascular anomalies treated with this material are highly unlikely to require retreatment as a result of recanalization. 

A common problem with expandable implants that are delivered through catheters is failure to deliver the device if it expands too quickly and can no longer be advanced. Because of this complication, a working time must be defined. Working time is fhe amounf of time from device introduction into the catheter to the time at which the device can no longer be retracted or advanced within the catheter (Nambiar et al., 2008  

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