Patent ID: 6746475
Filing Date: 2004-06-08
Classification: A61F,C21D

Abstract:
A stent adapted for advancement through a catheter in an upstream to downstream direction to a target vessel site in a contracted stent condition, and with expulsion from the catheter, downstream end first, and radial expansion at the target site, for engaging the walls of the vessel, said stent comprisinga continuous helical ribbon of a constant pitch formed of a shape-memory alloy; said stent having a downstream end and an upstream end and being substantially cylindrical, wherein the entirety of the stent forms a single conduit, the stent having a bending-stiffness gradient along its length due to one or more of the following: (i) a gradient of ribbon width, greater ribbon width at the upstream end of the stent, and lesser ribbon width at the downstream end of the stent, wherein the ribbon width progressively decreases from the upstream end in a downstream direction along the entire length of the stent, such that the width of the continuous helical ribbon at any point is greater or equal to the width of the continuous helical ribbon at any other point which is downstream; and (ii) a gradient of size or number of openings per unit length formed in the continuous helical ribbon, wherein the size or number of openings per unit length progressively increases from the upstream end in a downstream direction along the entire length of the continuous helical ribbon.