Abstract: A stent (10) formed from cannula and having flexible segments (11) and high hoop strength segments (12) alternating therealong. Axial tie bars (21,22) interconnect the segments; minimal length reduction would occur upon expansion. In the high hoop strength segment (12), struts (16) are initially parallel in the unexpanded strut condition, while in the flexible segment (11), struts (14) extend from a respective bight (15) to converge at distal ends when unexpanded. In one embodiment, certain adjacent struts (16) of the hoop segment are spaced apart by a large gap (20) while others are spaced apart by a small gap (18). In another embodiment all the struts (16) of the hoop segment are spaced apart uniformly from each other (or from an axial tie bar) by a small gap (23), resulting in minimizing the occurrence of fatigue of high-stress sites upon expansion/contraction cycles from continuous pulsatile events.

Abstract: A radially expandable stent (10) made from a cannula or sheet of biocompatible material that includes at least one longitudinal segment (14) comprised of a series of laterally interconnected closed cells (13). Each closed cell of a longitudinal segment is defined laterally by a pair of longitudinal struts (15, 16) that are interconnected at each end by a circumferentially adjustable member (19, 20). When the stent is expanded using a balloon (47), the opposing circumferentially adjustable members deform to allow circumferential expansion of the longitudinal segment, while the length of the segment, as defined by the longitudinal struts, is maintained. Self-expanding versions of the stent utilize a nickel-titanium alloy. Adjacent longitudinal segments are joined by flexible interconnection segments (21) that permit the stent to bend laterally. The flexible interconnection segment is comprised of curvilinear struts (22, 23) that form a series of serpentine bends (81) that distribute lateral bending forces.