Stents are medical devices commonly used to maintain patency of diseased body vessels, such as those of the vascular and gastrointestinal systems. Stents are often delivered via a minimally invasive procedure and thereafter expanded to contact and support the inner wall of the targeted vessel. In general, most stents include a tubular shaped support structure having a plurality of interstices configured to facilitate compression and expansion of the stent.
Many stents define the tubular shaped structure by weaving a plurality of strands together in a traditional weave pattern, where the strands overlap each other in an alternating fashion, with two major weaving directions. The weaving directions are ultimately in a helical shape, with a first set of strands extending around the stent in the first helical direction, and a second set of strands extending around the stent in a second helical direction that is transverse to the first helical direction.
Many stents define a proximal and distal end of the woven tubular structure, where the ends of the strands terminate to define the proximal and distal ends. The strands are typically in the form of individual wire, so the terminal ends are generally sharp at the proximal and distal ends.
In many instances, the stents include proximal and distal flanges or flared ends to prevent stent migration subsequent to implantation. Flanges or flares are typically set to a larger expanded diameter relative to the stent central portion and may exert a higher radial force per unit area against the vessel wall, thereby securing the stent in position. One problem with these features, however, is that the flanges or flares can damage the vessel wall if they are excessively rigid, especially in light of the sharp ends of the strands. The resulting tissue perforations may be painful and can lead to more serious complications including infection, hemorrhage, and possibly death.
Accordingly, there have been attempts to “treat” the sharp ends of woven stents to reduce the effects of the sharpness of the terminal ends. One method of treating the sharp ends of the woven stent includes welding or soldering a curved member to the sharp ends to join a pair of sharps ends to create a weld joint. However, fatigue stresses become concentrated at the weld joint, which can lead to breaking and exposing of a sharp end, which can lead to injury to the patient.