Embolic coiling

The Maitland research group is the leader in developing SMPs for clot-removal devices. In 2002, two studies were reported using thermoset polyurethanes for stroke treatment [45,46]. In the first study, an SMP device was manufactured as a wire that first punctures the clot, is then activated to coil on the distal side of the clot, and is then finally retracted for removal (Fig. 3) [45]. Using an in vitro setup, the prototype devices were shown to activate and hold a porcine blood clot at pressures up to ten times that of the neurovasculature. In a follow up study, laser activation of the shape-memory effect was investigated for the coil clot extraction device along with novel umbrella extraction devices and embolic coils [46]. Laser activation allows the devices to be heated past body temperature to trigger the shape-memory... 

One simple but smart example of a fibrous implantable medical device that uses the high surface ratio feature of fibers is embolization coil. Such devices are intended for many endovascular treatments of aneurysms, hemorrhages of peripheral lesions, and arteriovenous malformations. The procedure involves the threading of thin coils through a catheter into the affected area of the brain, filling the weakened portion of the vessel. Once in place, the body responds by forming a clot around the coil, further reducing the pressure and risk of rupmre. 

Embolic coiling involves the placement of a fine coil in a vascular defect to generate and maintain a clot. Initially coils were composed of steel guidewires lipped with cotton or wool strands that were navigated to the desired location through a catheter... 

There are also issues with frequent recanalization of treated vessels because the gel is resorbable, and as such, the gel may be fully resorbed before stable fibrosis occurs. Gelfoam use is often combined with embolic coils so that the gel creates the initial occlusion and the coils are implanted to retain the clot at the treatment region after the body begins resorbing the gelatin (Lubarsky et al., 2009 Vaidya et al., 2008). 

Currently embolic coils, such as those shovra in Figure 20.11, are the standard treatment for virtually all aneurysms with the exception of AAAs (Bederson et al., 2000). 

Fig. 22.5. Attaching adenoviral particles to embolization coils. Platinum and hio-degradahle coils were coated with collagen to provide a surface for subsequent attachment of an anti-adenovirus antibody. The derivatized coils were then incubated with the adenoviral vector which contained the gene for green fluorescent protein...

Abrahams et al. [1] recently reported linking an adenoviral vector to embolization coils. A diagram of the attachment strategy is shown as Figure 22.5. These initial experiments tested the feasibility of this approach both in vitro and in an animal model of intracranial aneurysms. A marker gene was used and expression of the marker protein was found in cells which were in contact with the coil. The animal experiments detected the marker protein in leuko-... 

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