Tapered self-expanding stent

Abstract

A self-expanding, tapered profile stent for implantation in a body lumen, such as an artery, is disclosed. The stent is constructed of a plurality of radially expandable cylindrical elements generally aligned on a common longitudinal stent axis and interconnected by one or more interconnecting members placed so that the stent is flexible in the longitudinal direction. The lengths of the cylindrical elements increase from one end of the stent to the opposite end by increasing the lengths of the struts and the lengths of the interconnecting members. Each cylindrical element is formed from repeating patterns of upright V's and inverted V's connected by straight strut arms with shoulders to create an overall serpentine wave pattern around the circumference. A step, continuous, parabolic, or curved taper in the stent can be imparted by using an expansion mandrel and applying deforming forces to the stent. The stent is made from pseudoelastic and shape memory alloys.

What is claimed is:  
     
         1 . A longitudinally flexible stent for implanting in a body lumen and expandable from a contracted state to an expanded state, comprising: 
 a plurality of adjacent cylindrical elements, each cylindrical element having a circumference extending around a longitudinal stent axis and being substantially independently expandable in the radial direction, wherein each cylindrical element is formed from struts arranged in a serpentine wave pattern;    wherein the plurality of adjacent cylindrical elements are arranged in alignment along the longitudinal stent axis, and wherein a plurality of cylindrical elements include sequentially increasing diameters to create a tapered profile;    a plurality of interconnecting members extending between the adjacent cylindrical elements and connecting the adjacent cylindrical elements to one another; and    wherein at least one of the plurality of struts and interconnecting members at the tapered profile increase in length along the longitudinal stent axis.    
     
     
         2 . The longitudinally flexible stent of    claim 1   , wherein the stent includes a pseudoelastic alloy material.  
     
     
         3 . The longitudinally flexible stent of    claim 1   , wherein the stent includes a shape memory alloy material.  
     
     
         4 . The longitudinally flexible stent of    claim 1   , wherein the plurality of interconnecting members are aligned end to end.  
     
     
         5 . The longitudinally flexible stent of    claim 1   , wherein the serpentine wave pattern of a cylindrical element further comprises a repeating strut pattern of upright V's and inverted V's.  
     
     
         6 . The longitudinally flexible stent of    claim 5   , wherein the strut pattern of upright V's and inverted V's of one cylindrical element is in phase with the strut pattern of V's and inverted V's of an adjacent cylindrical element.  
     
     
         7 . The longitudinally flexible stent of    claim 6   , wherein the strut pattern of upright V's and inverted V's of one cylindrical element nest into the upright V's and inverted V's of the adjacent cylindrical element.  
     
     
         8 . The longitudinally flexible stent of    claim 1   , wherein the serpentine wave pattern of a cylindrical element further comprises a repeating strut pattern of U's connected to W's.  
     
     
         9 . The longitudinally flexible stent of    claim 8   , wherein the serpentine wave pattern of a cylindrical element is out of phase with the serpentine wave pattern of an adjacent cylindrical element.  
     
     
         10 . A longitudinally flexible stent for implanting in a body lumen and expandable from a contracted state to an expanded state, comprising: 
 a plurality of adjacent cylindrical elements, each cylindrical element having a circumference extending around a longitudinal stent axis and being substantially independently expandable in the radial direction, wherein the plurality of adjacent cylindrical elements are arranged in alignment along the longitudinal stent axis and define a first end, a second and, and a center section;    wherein the center section is tapered when expanded such that the first end includes a small diameter and the second end includes a large diameter;    each cylindrical element formed from struts arranged in a serpentine wave pattern;    a plurality of interconnecting members extending between the adjacent cylindrical elements and connecting the adjacent cylindrical elements to one another; and    wherein in the expanded state of the stent, a distance between adjacent cylindrical elements increases from the first end to the second end.    
     
     
         11 . The longitudinally flexible stent of    claim 10   , wherein the plurality of interconnecting members are aligned end to end.  
     
     
         12 . The longitudinally flexible stent of    claim 10   , wherein the serpentine wave pattern of a cylindrical element further comprises a repeating strut pattern of upright V's and inverted V's with each upright V and inverted V including a shoulder.  
     
     
         13 . The longitudinally flexible stent of    claim 10   , wherein the serpentine wave pattern of a cylindrical element further comprises a repeating strut pattern of U's connected to W's.  
     
     
         14 . The longitudinally flexible stent of    claim 10   , wherein the stent includes a nickel-titanium alloy.  
     
     
         15 . A method for providing a longitudinally flexible stent for implanting in a body lumen and expandable from a contracted state to an expanded state, the method comprising the steps of: 
 providing a plurality of adjacent cylindrical elements, wherein each cylindrical element has a circumference extending around a longitudinal stent axis and is substantially independently expandable in the radial direction;    arranging the plurality of adjacent cylindrical elements in alignment along the longitudinal stent axis to define a first end, a second end, and a center section;    providing a tapered profile in the center section when expanded by providing small diameter cylindrical elements in the first end and gradually increasing the diameters toward the second end;    forming a serpentine wave pattern in each cylindrical element;    providing a plurality of interconnecting members extending between the adjacent cylindrical elements;    connecting the adjacent cylindrical elements to one another using the interconnecting members; and    wherein when the stent is in the expanded state, a distance between adjacent cylindrical elements increases from the first end toward the second end.    
     
     
         16 . The method of    claim 15   , wherein the step of forming the serpentine wave pattern further comprises forming a repeating strut pattern of upright V's and inverted V's.  
     
     
         17 . The method of    claim 16   , wherein the step of forming the serpentine wave pattern further comprises nesting the upright V's and inverted V's of one cylindrical element with an adjacent cylindrical element by arranging the serpentine patterns in phase and shortening the interconnecting members.  
     
     
         18 . The method of    claim 15   , wherein the step of forming the serpentine wave pattern further comprises forming a repeating strut pattern of U's connected to W's.  
     
     
         19 . The method of    claim 15   , wherein the step of providing a plurality of adjacent cylindrical elements includes forming the cylindrical elements from shape memory alloy material.  
     
     
         20 . The method of    claim 15   , wherein the step of providing a plurality of adjacent cylindrical elements includes forming the cylindrical elements from a pseudoelastic alloy material.