Temporary, repositionable or retrievable intraluminal devices

Abstract

A stent formed of a metallic material having a two-way memory adapted to be retrieved or repositioned after delivery includes an elongated tubular body and at least one crown connected to a respective longitudinal end of said body, the crown including a plurality of unconnected leaves, each leaf having a longitudinally extending frame connected at one end to said end of said body. A method of manufacturing the stent so that the crown has a greater two-way memory effect than the body is disclosed.

We claim:  
     
         1 . A stent formed of a metallic material having a two-way memory, said stent comprising; 
 an elongated tubular body; and    at least one crown connected to a respective longitudinal end of said body, said crown including a plurality of unconnected leaves, each leaf having a longitudinally extending frame connected at one end to said end of said body.    
     
     
         2 . A stent as recited in  claim 1  wherein said stent includes a pair of crowns, each crown connected to a respective end of said stent body.  
     
     
         3 . A stent as recited in  claim 1  wherein each leaf of said crown has an arrowhead shape.  
     
     
         4 . A stent as recited in  claim 1  wherein said crown has a greater two-way memory effect than said body  
     
     
         5 . A stent as recited in  claim 1  wherein said leaf comprises a single arrowhead-shaped frame.  
     
     
         6 . A stent as recited in  claim 1  wherein the lengths of all of said leaves of said crown are substantially the same.  
     
     
         7 . A stent as recited in  claim 1  wherein said leaves of said crown have different lengths.  
     
     
         8 . A stent as recited in  claim 1  wherein said plurality of leaves includes from two to eight leaves.  
     
     
         9 . A stent as recited in  claim 1  wherein said crown includes a plurality of pairs of equal-length leaves situated at diametrically opposed regions of said stent body end to which said crown is connected.  
     
     
         10 . A stent as recited in  claim 9  wherein the leaves of each of said pairs have the same length which is different from the length of the leaves of other pairs of leaves.  
     
     
         11 . A stent as recited in  claim 10  wherein said crown comprises two pairs of diametrically opposed leaves.  
     
     
         12 . A stent as recited in  claim 1  wherein each frame of each leaf includes a plurality of struts, two of said struts converging at one of their ends to form a peak.  
     
     
         13 . A stent as recited in  claim 1  wherein said stent body comprises an annular ring constituting said end of said stent body to which said crown is connected, said annular ring defining a plurality of peaks.  
     
     
         14 . A stent as recited in  claim 13  wherein each frame of each leaf includes a plurality of struts, two of said struts connected at one of their ends to respective peaks of said annular ring.  
     
     
         15 . A stent as recited in  claim 14  wherein said two struts are connected to adjacent peaks.  
     
     
         16 . A stent as recited in  claim 14  wherein said two struts are connected to every other peak.  
     
     
         17 . A stent as recited in  claim 14  wherein said two struts are connected to every third peak.  
     
     
         18 . A stent as recited in  claim 14  wherein said two struts are connected to every fourth peak.  
     
     
         19 . A stent as recited in  claim 1  wherein each leaf includes an outer frame and an inner frame.  
     
     
         20 . A stent as recited in  claim 19  wherein said outer and inner frames of each leaf define a plurality of inner cells.  
     
     
         21 . A stent as recited in  claim 20  wherein said inner cells of each leaf are symmetrically arranged.  
     
     
         22 . A stent as recited in  claim 19  wherein said outer and inner frames of each leaf are connected to each other.  
     
     
         23 . A stent as recited in  claim 19  wherein said outer and inner frames of each leaf are unconnected to each other.  
     
     
         24 . A stent as recited in  claim 19  wherein said stent body comprises an annular ring constituting said end of said stent body to which said crown is connected, said annular ring defining a plurality of peaks; and wherein 
 said outer frame of each leaf includes a plurality of struts, two of said struts connected at one of their ends to respective non-adjacent peaks of said end annular ring, defining at least two intermediate peaks between them; and wherein  
 said inner frame of each leaf including a plurality of struts, two of said struts connected at one of their ends to respective intermediate peaks of said end annular ring.  
 
     
     
         25 . A stent as recited in  claim 24  wherein said outer and inner frames of each leaf define a plurality of inner cells.  
     
     
         26 . A stent as recited in  claim 1  wherein said frame of each leaf includes a pair of base struts connected to the end of said body and a pair of main struts converging to form a peak.  
     
     
         27 . A stent as recited in  claim 1  wherein said stent body comprises a plurality of interconnected closed-cell rings and Z-rings, and wherein the end ring of said stent body to which said crown is connected comprises a closed-cell ring.  
     
     
         28 . A stent as recited in  claim 1  wherein said stent body comprises a central segment formed of at least one closed-cell ring and a pair of segments adjacent to said central segment formed of at least one Z-ring.  
     
     
         29 . A stent as recited in  claim 28  wherein said stent body comprises a pair of end segments formed of at least one closed-cell ring.  
     
     
         30 . A stent as recited in  claim 1  wherein said stent is formed of Nitinol.  
     
     
         31 . A stent as recited in  claim 1  wherein said crown has a length about equal to the length of the diameter of said stent body.  
     
     
         32 . A stent formed of a metallic material having a two-way memory, comprising: 
 a stent having at least two segments which are formed with different respective geometries; and    wherein one of said segments has a greater two-way memory effect than another segment.    
     
     
         33 . A stent as recited in  claim 1  wherein said stent body comprises a plurality of interconnected closed-cell rings.  
     
     
         34 . A stent as recited in  claim 1  wherein said stent body comprises a plurality of interconnected Z-rings, including the end ring of said stent body to which said crown is connected.  
     
     
         35 . A stent as recited in  claim 1  wherein the number of said leaves of said crown circumferentially is less than the number of cells or peaks at the end ring of said body to which the crown is attached.  
     
     
         36 . A stent as recited in  claim 1  wherein said leaves of said crown have an elongated geometry in respect to the cells and Z-rings in said body of said stent.  
     
     
         37 . A method of manufacturing a stent from a small diameter tube, said stent including an elongated tubular body and at least one crown connected to a respective longitudinal end of said body, said crown including a plurality of unconnected elongated leaves, each leaf having a longitudinally extending frame connected at one end to said end of said body, comprising the steps of: 
 performing a first laser-cutting of the small diameter tube with a plurality of thin linear slots to define for said tubular body a plurality of interconnected annular rings and for said crown, a plurality of leaves that are connected to adjacent leaves;    expanding the small diameter tube; and    performing a second laser cutting to disconnect each leaf from its adjacent leaves.    
     
     
         38 . The method of  claim 37  wherein each of said leaves includes a frame having a pair of base struts interconnected to the end of the stent body, and wherein 
 said first laser-cutting step includes forming adjacent base struts of adjacent frames of adjacent leaves as an integral elongate member; and wherein  
 said second laser-cutting step includes laser-cutting said integral elongate members to form unconnected pairs of adjacent base struts.  
 
     
     
         39 . A method of manufacturing a stent from a small diameter tube, said stent including an elongated tubular body and at least one crown connected to a respective longitudinal end of said body, said crown including a plurality of unconnected elongated leaves, each leaf having a longitudinally extending outer frame having a pair of outer struts connected at their ends to said end of said body and a longitudinally extending inner frame having a pair of inner struts unconnected to each other, comprising the steps of: 
 performing a first laser-cutting of the small diameter tube with a plurality of thin linear slots to define for said tubular body a plurality of interconnected annular rings and for said crown, a plurality of leaves, said inner struts of each of said inner frames of each leaf being connected to each other;    expanding the small diameter tube; and    performing a second laser-cutting to disconnect said inner struts of each of said inner frames from each other.    
     
     
         40 . A method of manufacturing a stent from a shape memory alloy, said stent including a tubular body having expanded and collapsed configurations and at least one crown connected to a respective longitudinal end of said body, said crown including a plurality of unconnected longitudinally extending elongated leaves, each leaf connected at a base to said end of said body, comprising the steps of: 
 imparting a two-way memory effect to said stent body by subjecting it to repetitive training cycles, each cycle including the steps of cooling the stent body in its expanded configuration, deforming the stent body to its collapsed configuration, and heating the stent body so that it returns toward an expanded configuration; and    either before or after imparting a two-way memory to said stent body, imparting an enhanced two-way memory to said crown by subjecting each leaf of said crown to repetitive training cycles, each cycle including the steps of cooling the leaf, over-deforming the leaf to an over-deformed configuration, and heating the leaf so that it returns toward said longitudinally extending configuration.    
     
     
         41 . The method of  claim 40  wherein said step of over-deforming each leaf includes bending the leaf at its base inwardly so that it extends into the stent body.  
     
     
         42 . The method of  claim 41  wherein said bending step includes bending each leaf about 180°.