Stent location

Brandname Type of graft Stent location Aortic diameter sizes Aortic length sizes Bifurcated diameter sizes Bifurcated length sizes... 

The Cook Zenith AAA endovascular graft was approved for use by the FDA in May 2003 (FDA 2013). It contains three different components the main graft module, the contralateral limb module, and the ipsilateral iliac extension (Fig. 21.12). All of these are constructed with a full-thickness woven polyester fabric attached to self-expanding stainless steel Cook-Z stents with braided polyester and monofilament polypropylene sutures. The distal end of the main body has a bare stainless steel stent designed to allow suprarenal fixation without disrupting blood flow through the renal arteries (Fig. 21.13). The stent also has hooks on each strut spaced 3 mm apart that are intended to dig into the aortic wall and prevent migration (Fig. 21.13). The proximal covered stent, located just below the bare suprarenal stent. 

One of the most commonly used medical devices is the stent, (Fig. 21.1), small metallic structures that are expanded in blood vessels, functioning to maintain the patency (freedom from obstruction) of the vessel in which it is placed. Although the first use of stents was in vasculature (blood vessel systems), more recent applications include, for example, implantation between two vertebrae to increase the rigidity of the spine. A typical vascular stent is placed in its anatomical location and then either plastically deformed/expanded (stainless steel) or allowed to expand to a predetermined size, as a consequence of shape memory (nitinol). 

Stent placement in PAD patients has also been an area of smdy and controversy. A meta-analysis examining the use of stent placement versus PTA for the treatment of aortoiliac occlusive disease determined that, although stent placement and PTA yielded similar complication and mortality rates, posttreatment ABI were more improved with stents (0.87 with PTA and 0.76 with stents,/ <0.03) and the risk of long-term failure was 39% less with stent placement." However, other studies have not demonstrated improvement in patency rates in peripheral arteries versus PTA alone. The TASC document provides specific recommendations for PTA, with or without stenting, depending on how diffuse the disease process is, the number and size of the lesions, and the location of the lesions. ... 

Heart-valve housing and struts and stents, housings for artificial heart, composites to control torque and steering of catheters. Radiopaque fillers in polymers to identify location on x-ray... 

Brandname Manufacturer Location of manufacturer Date of FDA approval Withdrawal date Type of aneurysm Type of stent... 

Currently there is only one prefenestrated endovascular stent-graft system approved by the FDA for use in the United States. It is an iteration of the Cook Zenith called the Cook Zenith Fenestrated . It is custom-made for each patient based on their personal aortic anatomy. This requires detailed CT scans of the abdominal aorta to properly locate the renal arteries and the superior mesenteric artery. The device is then manufactured with holes in the top piece for the renal arteries and a scallop at the top for the superior mesenteric artery (Fig. 21.19). These fenestrations are usually supported by a nitinol metal ring sewn around the circumference of the fenestration, as seen in the image taken from the study by Halak et al. (2006) (Fig. 21.20). 

In the case of drug-containing stents, the advantages of inkjet technology result from the controllable and reproducible nature of the droplets in the jet stream and the ability to direct the stream to the exact locations on the surface of the device. 

Fig.5.78a-c. Conventional angiography. a,b Before and after stent placement in combination with platinum coils to treat two small proximal located basilar stem aneurysms, c A 6 month control angiography demonstrated complete obliteration of the two aneurysms, the distal markers of the stent are slightly seen (arrow)... 

The circulatory fluid is ejected by an electropneumatically driven ventricular pump. Downstream of the pump, an aortic valve assembly is located two different models have been built in order to offer lateral or frontal view of the prosthesis movements. Suitable stent adapters allow to test prostheses of different type and size. The aorta is a variable compliance rubber tube. Through a rigid conduit the fluid is conveyed to the laminar flow assembly which controls peripheral resistances. Aortic compliance and peripheral resistances are hydropneumatically controlled. The fluid, passing through a venous reservoir open to atmospheric pressure, reaches the left atrium. This is a rigid wall chamber in which a hydropneumatic system relates cardiac output to venous return, reproducing Frank--Starling s Law. Between atrium and ventricle there is another valve test assembly which allows to test mitral valves. 

The stent is advanced across the stricture until the tip is 3-4 cm beyond the ampulla. It is preferable to start deployment with the stent too far in, rather than not far enough, because it is easier to withdraw the stent into the correct position than it is to move it forward (Fig. 1.5). The peel-away sheath is retracted (not peeled) to above the stricture. The delivery-system outer sheath is retracted a few centimeters, which allows the distal uncovered end of the stent to partially expand. Accurate placement, with the tip just through the ampulla, is achieved by pulling back the whole assembly over the wire. As the partially expanded stent is withdrawn across the ampulla, the stent is mildly compressed, which corresponds to the location of the ampulla. The stent is positioned so that the distal 1-2 cm projects into the duodenum. After confirming that the upper end of the stent is within the ducts and well above the stricture, the stent is fuUy released by full retraction of... 

If the location of the fistula is very close to the cricopharyngeus muscle, there may not be enough room to place a covered stent so that the fistula is sealed without compromising the upper esophageal sphincter. In this situation, it may be possible to seal... 

---