STENT HAVING HELICAL ELEMENTS
An expandable stent comprised of a plurality of helical segments is disclosed. In one embodiment, the stent is generally cylindrical in shape having a cylindrical axis, and comprises a first and second set of helical segments. The helical segments in the first set are substantially parallel and have a first pitch forming a first helical angle with respect to the cylindrical axis. The helical segments in the second set are also generally parallel to each other and form a second pitch that differs from the first pitch, thereby forming a second helical angle with respect to the cylindrical axis. In an alternative embodiment, the stent comprises one set of helical segments and a plurality of circumferential elements that are joined together by the helical segments to form a plurality of cylindrical elements which are joined together to form a stent body. The stent may also have endzones.
1 . An expandable stent having an unexpanded state, the unexpanded stent comprising:
a plurality of cylindrical elements having collinear cylindrical axes; and
a plurality of expandable helical segments comprising expandable circumferential segments each having a single substantially S-shaped portion and substantially H-shaped connecting segments, wherein the cylindrical elements are attached to one another by the H-shaped connecting segments.
2 . The stent of claim 1 , wherein the circumferential segments further comprise a plurality of segments joined together to form a repeating pattern.
3 . The stent of claim 2 , wherein the repeating pattern comprises a square wave form having curved peaks and valleys.
4 . The stent of claim 1 , further comprising first and second endzones straddling a main body of the stent.
5 . The stent of claim 4 , wherein each endzone comprises a plurality of rings joined together by a plurality of struts.
6 . The stent of claim 5 , wherein the rings are comprised of a plurality of alternating linear and curved segments.
7 . The stent of claim 1 , wherein each cylindrical element comprises: (1) a first plurality of the expandable circumferential segments and (2) a second plurality of circumferential segments, wherein the first and second pluralities of circumferential segments are joined to each other by at least one of the S-shaped portion or H-shaped segment.
8 . The stent of claim 7 , wherein the first and second pluralities of circumferential segments comprise a majority of the circumference of each cylindrical element.
9 . The stent of claim 7 , wherein the first circumferential segments alternate with the second circumferential segments.
10 . The stent of claim 7 , wherein the circumferential dimensions of the first and second pluralities of circumferential segments are equal.
11 . The stent of claim 7 , wherein the circumferential dimension of at least one of the second plurality of circumferential segments is larger than the circumferential dimensions of the first plurality of circumferential segments.