Fibrous implantable medical devices

Smart features in fibrous implantable medical devices... 

Figure 13.1 Textile science contribution to smart fibrous implantable medical devices designing. Biocompatibility and well-functioning implants in the postoperative stage will be focused on in this review.

The importance of these three scale levels has been progressively pointed out as the fibrous implantable medical devices area evolves. Vascular prostheses evolution is a representative example. These medical devices developed in the 1950s, and since have improved a great deal. Currently, there are still weaknesses in vascular prostheses and research studies are still undergoing to overcome them. 

This example of vascular grafts devices points out the evolution of fibrous implantable medical devices and highlights the great potential offered by each scale level of fibrous structures for biocompatibility improvements. Fibers as well as whole fibrous stmctures should be considered as implantable devices that have inherent abilities to interact with the biological environment at each of the three predetermined scale levels. Study of characteristics and specificities of fibers, fibrous siuface, and fibrous volume should then provide a more forward-looking approach in the textile substitute s area for design and achievement of smart medical implantable textile devices. 

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. 

Fiber capillary action Apart from improved adsorption of biological fluids thanks to fiber high surface ratio, capillary action of fibers also contributes to cells adhesion onto the fibrous implantable medical device. Capillarity is the action by which pores in a solid transport liquid on contact, so that tissue fluids transfer from the wet end to the dry end. The kinetics of the fluid transport are governed by the surface tension... 

Depending on the nature of used material in fibrous implantable medical device design, degradation products take different forms. As previously described, polymer degradation usually results in monomer solubilization. Degradation of metallic material occurs by metal ions released at exposed weak surfaces of the material. Moreover, degradation of material in the biological environment may happen at the structural level and be associated with debris and particle release. 

Permanent materials could be thus designed to provide smart fibrous implantable medical devices with improved performance and decreased amount of particle release to give better biocompatibihty. 

Fibrous devices as drug delivery system Drug delivery is perhaps one of tlie most explored active feamres of fibrous implantable medical devices. The search for improved drug administration efficiency has led to explore potential dmg delivery systems and dmg reservoirs. As the effectiveness of a dmg is a dose-dependent release profile, adsorption by tissue and disposal, it has been assumed that implantable fibrous medical devices may be used to carry and release the dmg with local effect, an advantageous large volume of embedded dmgs thanks to high surface/volume ratio... 

These examples underscore the wide range of material physical characteristics that remain to be explored to improve fibrous implantable medical devices and make them even smarter for each intended application. While some of these smart characteristics could be easily identified, such as radio-opacity, radioresistance, and resistance to sterilization, wettability, the fibrous material area is a vast exploratory field that is not as well known and described as the fibrous stmctures area. 

For this reason, it has been proposed to focus on physical features, reviewing only one specific material, carbon nanotubes, rather than attempting to list material features that may induce potential improvement of fibrous implantable medical devices from biointegration and efficiency points of view. 

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