Nitinol mesh

This stent has been modified from the original Strecker stent and consists of a woven nitinol mesh. It is available in covered and uncovered versions (Fig. 2.4), and... 

The use of PHA coatings to enhance biocompatibility of vascular stents was shown to be an effective modification. Self-expanding nitinol mesh vascular stents were coated with PHA and PHA loaded with an antiproliferative drug. Stents were placed in the femoral artery of dogs and examined for 120 days. The analysis of the state of the vessels and morphometric examination showed the effectiveness of coating vascular stents with PHA, especially PHA loaded with an antiproliferative drug. Reactive changes in the vessel wall were less pronounced and no complications occurred that are usually caused by implantation of uncoated metal stents (Protopopov et al. 2005, 2008). 

The characteristic feature of all Amplatzer devices is the nitinol wire mesh. There are two possible methods of implantation. Either the device is placed entirely into the appendage or the distal disc is expanded in the neck and the proximal disc in the left atrium. The risk of residual shunting around the device is increased when it is totally inserted into the LAA with no part protruding into the atrium. The Amplatzer occluder series holds the widest spectrum of device sizes (4 to 40 mm), The device is attached to a delivery cable and can simply be opened or recollapsed into the delivery catheter. Release is by unscrewing the device after first testing stability with simple traction. 

The Fortevo device from Aptus capitalizes on Aptus experience with their endovascular Helifx anchoring device, which is similar to the helical tacks used to fix meshes in laparoscopic hernia repair. The Fortevo is a modular device made from nitinol stents and a woven polyester graft. This device uses separate endoanchors to secure the proximal fixation zone. 

The Ultraflex nitinol stent comes in both covered and uncovered versions (Fig. 3.4). It has a significantly lower radial expansile force than the other stents but the covered version is much more flexible than any of the other covered stents and may therefore be placed across acutely angled stenoses (Repici et al. 2000). The stent is available with a 23-mm mid diameter and a 28-mm funnel-shaped proximal end and is mounted on a 16-F delivery catheter. The stent consists of a nitinol wire mesh with a polyurethane external membrane which leaves both stent ends bare for 1.5 cm for better fixation. 

Figure 20.8 Image of an Amplatz canine duct occluder (ACDO), which shows the fine nitinol wire mesh used as an embolic device to completely occlude patent ductus arteriosus (PDA) in dogs.

One of the most widely used and successful devices for percutaneous PFO closure is the Amplatzer PFO Occluder (St. Jude Medical Inc., St. Paul, MN), which is a device consisting of two nitinol discs that contain a polypropylene mesh (Meier, 2009). These types of devices have demonstrated complication rates of less than 5% and procedural success in 100% of cases (Taaffe et al., 2008). However, only 65% of the patients showed complete occlusion of the foramen ovale at 30 day follow-up. New generations of PFO closure devices could benefit from tissue scaffold technologies to allow rapid healing and tissue integration to achieve complete occlusion of PFOs at... 

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