Multi-filar coil medical stent

Abstract

Multi-filar, open and closed coil, tubular medical stents that are introduced to a site in a body lumen and released to expand at the site to provide a passageway through the stent lumen are disclosed. Each stent filar is a coil wound in substantially the same pitch through the majority of its length between the ends thereof. The coils are attached together at least at one coil end to form an end of the stent and wound in an interleaved manner such that the adjacent coils are substantially evenly spaced apart or in close contact in the released state and do not cross over one another. In one open coil stent embodiment, both ends of each coil are attached in respective first and second common attachment junctions, and the resulting coils have relatively even predetermined spacing between adjacent coil turns through the majority of the length of the stent between the first and last coil turns when the stent is released. Preferably, the first and second stent ends are formed by attaching the coil ends in common, and the stent ends are squared by decreasing the pitch of the first coil turn extending from the stent end such that the spacing of the stent end from the adjacent coil is reduced from the predetermined spacing. Additionally, multi-filar closed coil stent embodiments are disclosed having only one end of each coil attached in common and adjacent coil turns in substantial mutual and overlying contact in the restrained state during implantation and non-overlying contact in the released state. Preferably each common attachment junction of attached coil ends and each free coil end is formed into an enlarged stent end in at least one dimension for ease of attachment to and release from a stent delivery catheter. The common attachment junction can be snared or grasped by a stent retrieval system and retracted from the body lumen.