Esophageal Cancer. Part 3
Finally, the last self-expanding stent is the Wilson-Cook Z stent. This is a stainless steel product with interlocking mesh triangles, again with a polyurethane coating to prevent tumor ingrowth. It comes in different sizes. One of the nice features of this stent is when it is deployed there is very minimal retraction. That is, when the stent pops in it doesn’t shrink down very much, so you can very accurately gauge the placement of this stent and that is really handy when you are placing a proximal esophageal stent where you are worried about respiratory compromise, and a few other applications as well.
This table is in your syllabus but it kind of outlines some of the specs of the different stents. But keep in mind, the size of the delivery system is very important. If you have a large delivery system that is going to require a number of dilation maneuvers perhaps to place that, whereas if you have a very small delivery system, 18 French or 24 French, it’s quite easy to pop this in without even a single dilation maneuver. Four of the five stents are now covered, and that’s important for preventing tumor ingrowth and also for sealing tracheoesophageal fistulas. The radial force is quite different. If you’ve ever felt the EsophaCoil, it has kind of a firm, strong feel. Whereas the Ultraflex seems quite flimsy but they have different properties there. And again, degree of shortening is very important. I’ve mentioned the Z stent has very little shortening that occurs.
I’m going to show a little video tape again. The placement of a couple of stents. For those of you who haven’t been doing this much, just to show … first, the EsophaCoil. This is typical adenocarcinoma of the distal esophagus. It’s important to note where the tumor is so you have to mark the tumor margins both externally and internally. This is injecting radiocontrast, either lipid or water soluble. There’s already a mark distally. I think you can just see it, and now injection proximally into the margin of the tumor so you can gauge your stent placement. You have to size your stents. They come in different sizes, different diameters of course. We try to get at least 2-3 cm of stent beyond the proximal and distal margins in order to allow for the shrinkage which may occur. Once the stent is passed through the stricture area, the EsophaCoil has kind of a tricky delivery system. You have to release three different tabs. The first tab is the distal release, which releases the … kind of a string release device which allows the distal part to be released. And you turn the device and release the proximal portion of the stent. Again, you notice the shrinkage which occurs, a fairly significant amount. It kind of bunches up and then finally the middle part right across the stricture is released, which allows the full deployment of the stent and hopefully the coils are all fitting together nicely like they are supposed to. Again, keeping in mind that this is important when you gauge what size of stent you should put in. If you have a 6 cm tumor you probably want at least a 10 cm or 12 cm stent, especially when using a device like this.