Stents are tubular shaped medical devices commonly used to maintain patency of diseased body vessels. Stents may be implanted to treat blockages, occlusions, narrowing ailments, and other problems that can restrict flow through a vessel. Stents can be implanted, for example, in the coronary and peripheral arteries to maintain blood flow, in the ureters and biliary tract to provide drainage, and in the esophagus to palliate dysphagia.
Stents are often delivered in a radially compressed state via a minimally invasive procedure and thereafter expanded to contact and support the inner wall of the targeted vessel. Both self-expanding and balloon-expandable stents are amenable to radial compression and subsequent expansion at the treatment site. Balloon-expandable stents expand in response to the inflation of a balloon, whereas self-expanding stents deploy automatically when released from a delivery device.
Self-expanding stents are useful for a variety of procedures requiring the patency of a bodily pathway. Such stents are generally biased to expand, such that when deployed, they assume an open position, pushing outward and into the surrounding area into which deployed. The radial expansion creates a pathway in a once occluded area.
One type of self-expanding stent includes single wire stents designed for implantation in the gastrointestinal system (e.g., esphophagus, colon, biliary tree, etc). These braided stent structures are flexible enough to accommodate typical movements of such bodily organs, but they simultaneously provide sufficient rigidity to maintain patency of the vessel. A single wire stent typically includes a helical weave or braid configuration where the wires of opposing helicals pass in an alternating fashion under and over each other. This inter-weaved pattern gives stability to the stent structure. However, the current manufacturing process for these types of single wire woven stents is extremely labor intensive and expensive, as they are typically hand woven with the assistance of a mandrel. For larger stents, it can take up to sixteen hours for a highly skilled artisan to manufacture the tubular frame utilizing a wire measuring about eight meters in length. This long wire is laboriously threaded together to form the final stent weave pattern. Automated machine processes are currently unavailable.