Patent Publication Number: US-2021161689-A1

Title: Stent with longitudinal variable width struts

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. application Ser. No. 16/116,612 filed on Aug. 29, 2018 which is incorporated herein by reference in its entirety herein into this application as if set forth in full. 
    
    
     FIELD OF INVENTION 
     The present invention generally relates to implantable stent medical devices, methods for manufacturing the same, and more particularly, to stents for treating wide-necked intracranial aneurysms. 
     BACKGROUND 
     Medical stents are used for supporting, maintaining, or repairing a lumen, passageway or opening in a living body. Stent design is unique to location and objective of the treatment as the stent must be flexible enough to navigate body lumen to arrive at a treatment site and then structurally robust enough to provide the required structural support to repair the treatment site. Compared with carotid arteries, the arteries inside the brain are very small and make many twists and turns, requiring a more flexible stent capable of not only navigating tight turns upon approaching a treatment site, but conforming to vessel walls within tight curvatures when implanted. Stents implanted to support embolic coil masses in cranial aneurysms must also be strong enough to maintain complete aneurysm neck coverage and serve as a scaffold or barrier to prevent the coils from protruding back into the parent blood vessel, particularly in the treatment of wide-necked aneurysms. 
     To meet the competing needs of flexibility and structural integrity, known stent designs typically include a plurality of circumferential rings or single helical coil designed to provide structural support joined by longitudinally extending bridges designed to achieve desired flexibility. A stent with a bridge at every joint is typically classified as a closed cell stent, and stent with many bridges removed is typically classified as an open cell stent. In general, open cell stents are more flexible than closed cell stents, making them easier to navigate tight curves when being delivered to a treatment site, or for increased conformability when treating a treatment site that includes a curve. However, the increased flexibility comes at the cost of loss of structural benefits such as scaffolding uniformity. Additionally, once deployed, open cell structures can be more difficult to recapture and reposition compared to closed cell stents. Closed cell designs typically have structural benefits such as scaffolding uniformity but at the cost of the flexibility and conformity required for intracranial treatments. 
     Known stents include the Cordis Enterprise® line of self-expanding stents, which are described in numerous patents and published patent applications including U.S. Pat. No. 6,673,106 which is hereby incorporated by reference hereinto. 
     There is therefore a need for an improved flexible neurovasculature stent capable of navigating tight curves to reach a treatment site, and once implanted conform to tight curvatures of vessel walls and maintain structural support for embolic implants. 
     SUMMARY 
     Disclosed herein are various exemplary stents of the present invention that can address the above needs, the stents generally can include multiple longitudinal elements each extending over a majority of the length of the stent and each having alternated flexible and rigid segments. The stents can include nodes positioned between the flexible and rigid segments on the longitudinal elements and interconnecting members extending circumferentially to connect adjacent longitudinal elements at the nodes. The longitudinal elements can have a wave pattern and the interconnecting members can have a branch structure connecting peaks from one longitudinal element to troughs of an adjacent longitudinal element. The resulting stent structure can have lateral and longitudinal flexibility needed to navigate and conform to intracranial arteries with the benefits of recapturability and structural integrity of a closed cell design. 
     In one example, a stent can be substantially tubular with a circumference and a length extending between a first open end and a second open end. The stent can have multiple longitudinal elements each having alternated thin and thick segments, and each longitudinal element can extend over a majority of the length of the stent. The stent can have interconnecting members that extend circumferentially to connect two adjacent longitudinal elements. The interconnecting members can have a plurality of branches. The stent can have a plurality of nodes positioned on the longitudinal elements between the alternating thin and thick segments. The nodes can connect the branches of the interconnecting members to the longitudinal elements. The thin segments and thick segments can respectively have uniform widths spanning between nodes such that the thick segments have a width that measures greater than the thin segments. 
     Each longitudinal element can have a sinusoidal shape. Each of the nodes can be positioned at a peak or a trough of the sinusoidal shape. 
     The interconnecting members can have thin branches and thick branches respectively having uniform widths such that the width of the thick branches measures greater than the thin branches. The interconnecting members can have four branches joined at two intermediate nodes. Of the four branches, a first branch can have a thin width and a second branch can have a thick width measuring greater than the thin width. 
     In another example a stent can have a substantially tubular shape with unit cells repeating in a clockwise direction, counterclockwise direction, and longitudinal direction. Each of the unit cells can have a longitudinally extending element extending the width of the unit cell in the longitudinal direction and forming one period of a wave pattern. The longitudinally extending element of the unit cell can have a clockwise note positioned at a trough of the wave pattern, a clockwise node positioned at a peak of the wave pattern, a thick segment of substantially uniform width extending from the counterclockwise node to the clockwise node, and a thin segment comprising a substantially uniform width measuring less than the width of the thick segment extending from the clockwise node to a longitudinally adjacent counterclockwise node of a longitudinally adjacent unit cell. The unit cell can have a clockwise extending branch extending from the clockwise node of the longitudinal element circumferentially in the clockwise direction. The unit cell can have a counterclockwise extending branch extending from the counterclockwise node of the longitudinal element in the counterclockwise direction. 
     The unit cell can have a first intermediate branch connecting a longitudinally adjacent counterclockwise extending branch extending from the longitudinally adjacent unit cell and a counterclockwise adjacent clockwise extending branch extending from a counterclockwise adjacent unit cell. The unit cell can have a second intermediate branch connecting the longitudinally adjacent counterclockwise extending branch and a diagonally adjacent clockwise extending branch extending from a unit cell counterclockwise adjacent the longitudinally adjacent unit cell. 
     The clockwise extending branch and the counterclockwise extending branch of the unit cell can each have a substantially uniform width that is about equal for both branches, and the first intermediate branch can have a substantially uniform width that measures less than the width of the clockwise extending branch and the counterclockwise extending branch. 
     The wave pattern of the longitudinal element can be in the shape of a sinusoid. 
     The width of the thick segment in the unit cell can measure about 0.0018 inches, and the width of the thin segment can measure about 0.00125 inches. 
     The stent can have a first end, second end, a length extending longitudinally between the first and second ends with unit cells repeating over a majority of the length, and end cells positioned approximate the first and second ends. Each end cell can have an end segment of the longitudinally extending element, an end branch of the interconnecting member, and a joining member connecting the end segment to the end branch. The end cells can repeat in the clockwise and counterclockwise directions around the circumference of the stent at the stent ends. 
     In another example, a stent can have a substantially tubular shape characterized by a circumference measured in a circumferential direction and a length measured in a longitudinal direction. The stent can have longitudinal elements extending over the length of the stent made up of alternating flexible segments and rigid segments such that the flexible segments and rigid segments provide structural support for the stent and the flexible segments are more flexible in the longitudinal direction compared to the rigid segments. The stent can have interconnecting members that each connect two adjacent longitudinal elements in the circumferential direction. The interconnecting members can each have multiple branches. The stent can have nodes positioned on the longitudinal elements between each of the alternating flexible and rigid segments. The nodes can connect the branches of the interconnecting members to the longitudinal elements. 
     The flexible segments can have a thin width and the rigid segments can have a thick width that is greater than the thin width. 
     The interconnecting members can each have a flexible branch and a rigid branch such that the flexible branch has a greater flexibility in the longitudinal direction compared to the rigid branch. 
     The longitudinal elements of the stent can have a wave shape characterized by peaks and troughs. Each node of the stent can be positioned at a peak or a trough, and each interconnecting member can connect peaks from a first longitudinal element to troughs from a second longitudinal element. 
     In an example method for manufacturing a stent, an elastic tubing with a circumferential direction and a longitudinal direction can be provided. The tubing can be cut to form a first alternating pattern of flexible struts and rigid struts extending in the longitudinal direction. Each of the flexible struts can be more flexible than each of the rigid struts as measured in the longitudinal direction. First nodes can be positioned at each intersection of the flexible struts and rigid struts of the first alternating pattern. The tubing can be cut to form first branches each extending from each of the first nodes. The tubing can be cut to form at least one adjacent alternating pattern of flexible struts and rigid struts extending in the longitudinal direction and positioned adjacent to the first alternating pattern in the circumferential direction. The first branches can be connected to each adjacent alternating pattern. 
     Each of the flexible struts can be cut to a substantially uniform thin width between a first pair of adjacent nodes, and each of the rigid struts can be cut to a substantially uniform thick width between a second pair of adjacent nodes such that each of the flexible struts has a width that measures less than each of the width of each of the rigid struts. 
     Intermediate branches can be cut to extend from the first branches, and the intermediate branches can each have a width less than a width of the first branch from which it extends. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and further aspects of this invention are further discussed with reference to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating principles of the invention. The figures depict one or more implementations of the inventive devices, by way of example only, not by way of limitation. 
         FIG. 1A  illustrates a strut pattern of an unrolled stent according to aspects of the present invention. 
         FIG. 1B  illustrates a unit cell according to aspects of the present invention. 
         FIGS. 1C and 1D  illustrate a strut pattern of a stent according to aspects of the present invention. 
         FIG. 2  illustrates a strut pattern of a stent according to aspects of the present invention. 
         FIG. 3  illustrates a three-dimensional stent according to aspects of the present invention. 
         FIGS. 4 and 5  are a flow diagrams including steps that can be part of a method of manufacture of a stent according to aspects of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     A strut pattern of an example stent  100  is illustrated in  FIGS. 1A-1D . The example stent  100  is shown cut in a longitudinal direction  10  along its length  110  and laid flat.  FIG. 1A  illustrates an entire stent  100 ;  FIG. 1B  shows the details of a unit cell  130  as indicated in  FIG. 1A ;  FIG. 1C  illustrates the positioning of longitudinal elements  200  in relation to interconnecting members  300 ; and  FIG. 1D  illustrates the positioning of thin segments  210  of longitudinal elements  200  and thin segments  310  of interconnecting members  300 . 
     Referring collectively to  FIGS. 1A-1D , the stent  100  can be cut from an elastic tube such as nitinol, nitinol alloy, other memory shape metal, or elastic implantable tubing so that the stent  100  can have a substantially tubular structure having a first open end  112 , second open end  114 , a circumference  120 , and a length  110 . The strut pattern can be made up of longitudinal elements  200  that extend over a majority of the length  110  of the stent  100  that are connected in a circumferential direction  20  by branches of interconnecting members  300 . At each end  112 ,  114  of the stent  100 , end segments of longitudinal elements  200  can connect to end branches of interconnecting members  300  with end joining members  150 . The strut pattern can include thin segments  210 , 310  and thick segments  220 ,  322 ,  324 ,  326 . The pattern of the branches in the interconnecting members  300  can mimic the wave structure of the longitudinal element  200  to form a closed cell strut pattern. 
     The stent  100  illustrated in  FIGS. 1A-1D  has three longitudinal elements  200  placed circumferentially that are connected circumferentially by interconnecting members  300 , where each interconnecting member  300  is shown made up of four branches  310 ,  322 ,  324 ,  326 . As will be understood, the number of longitudinal elements  200  and the branch structure of the interconnecting members  300  can be tailored to the specific size and flexibility requirements for treatment. 
     Longitudinal elements  200  are shaded in  FIG. 1C  to differentiate longitudinal elements  200  from interconnecting members  300 . Longitudinal elements  200  can be made of alternating segments or struts that vary in width or flexibility.  FIG. 1C  illustrates elongated elements  200  having alternating thin segments  210  and thick segments  220 , for example. 
     Similarly, the branches of the interconnecting members  300  can vary in width or flexibility in an alternating fashion and can mimic the alternating pattern of the longitudinal elements  200 . Thin segments  210  of longitudinal elements  200  having a thin width  215  and thin segments  310  of the interconnecting members  300  having a thin width  315  are shaded in  FIG. 1D  to differentiate the thin segments  210 ,  310  from the thick segments  220 ,  322 ,  324 ,  326 . 
     Thinner segments having greater flexibility can contribute to the overall flexibility of the constructed stent  100  while thicker segments having greater rigidity can contribute to the overall structural strength of the constructed stent  100 . The constructed stent can have improved overall implant flexibility and conformability as can be quantized by a lower flexural modulus. The resulting constructed stent can have improved flexibility in both the longitudinal and lateral directions. 
     Thin segments  210  or thin branches  310  can be laser cut to have a thin width  215 ,  315 , for example about 0.00125±0.0003 inches, and thick segments  320  or thick branches  322 ,  324 ,  326  can be laser cute to have a thick width  225 ,  325 , for example about 0.00180±0.0003 inches. Thin segments  210  or branches can allow for increased flexibility while the thicker segments or branches can maintain the structural integrity of the stent  100  and resist kinking. 
     Strut configurations not shown that result in an alternating pattern of flexible and rigid segments are also contemplated. For example, strut configurations including alternating patterns of shorter and longer segments, or alternating patterns of struts having thinner or thicker depths in the radial direction of the stent can result in an alternating pattern of flexible and rigid segments. Additionally, or alternatively, for stents with longitudinal elements having a wave pattern, the wavelength and/or the amplitude of the wave pattern can be modified within the stent structure to alter the flexibility/rigidity of segments of said longitudinal elements and to control the overall flexural modulus of the stent. 
     Although not depicted in the figures, incorporating radiopaque material is also contemplated. For example, a coating of radiopaque material such as tantalum can be deposited on surfaces of the stent by means known in the art to enhance device visibility under fluoroscopy. In some applications, it can be advantageous to deposit a thin coating of radiopaque material on stent surfaces in low strain areas. 
     Referring to  FIGS. 1A-1B , the unit cell  130  pattern can repeat in a clockwise direction  22 , a counter-clockwise direction  24 , and a longitudinal direction  10 . As illustrated in  FIG. 1B , the unit cell  130  can have a longitudinal element  200  spanning across the width of the unit cell  130  and extending into longitudinally adjacent unit cells such that the longitudinal element  200  extends in a continuous and repeated fashion along the length  110  of the stent  100 . A clockwise extending branch  326  can extend from a clockwise node  252  positioned at a peak  202  of the longitudinal element  200  wave pattern. The clockwise extending branch  326  can be part of an interconnecting member  300  that connects the longitudinal element  200  to an adjacent longitudinal element  200  in the clockwise direction  22 . A counterclockwise extending branch  322  can extend from a counterclockwise node  254  positioned at a trough  204  of the longitudinal element wave pattern. The counterclockwise extending branch  322  can be part of an interconnecting member  300  that connects the longitudinal element  200  to an adjacent longitudinal element in the counterclockwise direction  24 . 
     To illustrate how unit cells can be interconnected,  FIG. 1B  shows a unit cell  130 , portions of a clockwise adjacent unit cell  132 , a counterclockwise adjacent unit cell  134 , a longitudinal adjacent unit cell  140 , a cell that is clockwise adjacent the longitudinal adjacent cell  142 , and a cell that is counterclockwise adjacent the longitudinal adjacent cell  144 . Each of the partial unit cells illustrated represent a complete repeating pattern of the unit cell. 
     As shown in  FIG. 1B , within the unit cell  130 , the longitudinal element  200  can have a thick segment  220  having a thick width  225  and a thin segment  210  having a thin width  215 . The thick segment  220  can have a substantially uniform thick width  225  spanning between a counterclockwise node  254  and a clockwise node  252 . The thin segment  210  can have a substantially uniform thin width  215  spanning between the clockwise node  252  and a counterclockwise node  254  of the longitudinally adjacent cell  140 . As the unit cell repeats along the length  110  of the stent  100 , the longitudinal element  200  can have a repeating pattern of alternating thick segments  220  and thin segments  210 . 
     Interconnecting members  300  can be made of branches that extend from the nodes  252 , 254  to connect longitudinal elements  200  in circumferentially adjacent unit cells. As shown in  FIGS. 1A and 1B , an interconnecting member  300  can have four branches within a unit cell  130 . As described above, the clockwise extending branch  326  can extend from a clockwise node  252  positioned at a peak  202  of the longitudinal element  200 , and a counterclockwise extending branch  322  can extend from a counterclockwise node  254  positioned at a trough  204  of the longitudinal element  200 . The branches can extend from the nodes of the longitudinal elements  200  at acute angles to facilitate collapsibility and flexibility of the stent  100 . 
     One or more of the branches extending from the nodes can also extend longitudinally between unit cells. For example, the counterclockwise extending branch  322  of the unit cell  130  is shown extending from a counterclockwise node  254  positioned in the longitudinally adjacent unit cell  140 . The longitudinal extension of the branch cell can facilitate collapse of the stent  100  and can mimic the wave pattern of the longitudinal element  200  to form a collapsible, flexible closed cell pattern. 
     The interconnecting member  300  can have intermediate branches connecting to the clockwise extending branch  326  and the counterclockwise extending branch  322 , joining a clockwise extending branch  326  from a unit cell to a counterclockwise extending branch  322  in a circumferentially adjacent unit cell. For example, a first intermediate branch  310  can extend in the counterclockwise direction  24  from a first intermediate node  352  positioned on an end of the counterclockwise extending branch  322  to a second intermediate node  354  positioned on an end of a clockwise extending branch  326  of the counterclockwise adjacent unit cell  134 . 
     In addition to extending in the counterclockwise direction  24 , the counterclockwise extending branch  322  and the first intermediate branch  310  can together extend longitudinally across the majority or the entirety of the unit cell  130  and can mimic the wave pattern of the longitudinal element  200  to provide continuity in the closed cell structure of the stent  100 . The first intermediate branch  310  can join the clockwise extending branch  326  of the counterclockwise adjacent unit cell  134  at an acute angle to mimic the attachment of branches  322 ,  326  to nodes  252 ,  254  at the longitudinal elements  200 . 
     A second intermediate branch  324  can extend in the counterclockwise direction  24  from the first intermediate node  352  to join a clockwise extending branch  326  of the unit cell counterclockwise adjacent the longitudinal unit cell  144 . In addition to extending in the counterclockwise direction  24 , the second intermediate branch  324  and the clockwise extending branch  326  of the cell counterclockwise adjacent the longitudinal adjacent cell  144  can extend longitudinally over a width about equal to a width of a unit cell, spanning longitudinally from approximately half way across the unit cell  130  to about half way across the cell counterclockwise adjacent the longitudinal adjacent cell  144 , and the longitudinal extension of the two branches can mimic the wave pattern of the longitudinal element  200 . The second intermediate branch  324  can join the counterclockwise extending branch  322  at the first intermediate node  352  at an acute angle to mimic the attachment of branches  322 ,  326  to nodes  252 ,  254  at the longitudinal elements  200 . 
     Branches in the interconnecting member  300  can have varying widths. For example, the first intermediate branch  310  can have a thin width  315  that is substantially uniform between the first intermediate node  352  and the second intermediate node  354 . As shown in  FIG. 1B , the clockwise extending branch  326 , the counterclockwise extending branch  322 , and the second intermediate branch  324  can each have a substantially uniform thick width  325  such that the thin width  315  measures less than the thick width  325 . 
     End cells  160  can include an end segment of a longitudinal element  200  and an end branch segment connected by an end joining member  150 . 
       FIG. 2  shows another visualization of an example strut pattern of the stent  100 .  FIG. 2  shows a first longitudinal element  200   a  and a second longitudinal element  200   b  positioned adjacent each other in the circumferential direction  20  and an interconnecting member  300  made up of branches that extend circumferentially to connect the adjacent longitudinal elements  200   a,    200   b.  Each longitudinal element  200   a,    200   b  has a wave pattern having peaks  202   a , 202   b  and troughs  204   a , 204   b  with an alternating pattern of thin segments  210   a , 210   b  and thick segments  220   a , 220   b  spanning between the peaks  202   a,    202   b  and troughs  204   a , 204   b . Nodes  254   a  positioned at troughs  204   a  of the first longitudinal element  200   a  connect to counterclockwise extending branches  322  of the interconnecting member  300 , and nodes  252   b  positioned at peaks  202   b  of the second longitudinal element  200   b  connect to clockwise extending branches  326  of the interconnecting member  300 . Nodes  252   a  can be positioned at peaks  202   a  of the first longitudinal element  200   a  to join with a clockwise adjacent longitudinal element (not shown), and nodes  254   b  can be positioned at troughs  204   b  of the second longitudinal element  200   b  to join with a counterclockwise adjacent longitudinal element (not shown). 
     The first and second longitudinal elements  200   a,    200   b  can be aligned such that peaks  202   a  of the first longitudinal element  200   a  align circumferentially with peaks  202   b  of the second longitudinal element  200   b  and troughs  204   a  of the first longitudinal element  200   a  align circumferentially with troughs  204   b  of the second longitudinal element  200   b.    
     First intermediate branches  310  and second intermediate branches  324  can span between first intermediate nodes  352  positioned at an end of the counterclockwise extending branches  322  and second intermediate nodes  354  positioned at an end of the clockwise extending branches  326 . The first and second intermediate branches  310 , 324  can extend longitudinally in opposite directions between the first intermediate nodes  352  and the second intermediate nodes  354  to form a pattern that mimics the wave pattern of the longitudinal elements  200   a , 200   b.  The first and second intermediate branches  310 , 324  can join end-to-end at first and second intermediate nodes  352 , 354  to span across most of the length  110  of the stent  100 . First intermediate nodes  352  can align circumferentially with peaks  202   a , 202   b  of the first longitudinal element  200   a  and the second longitudinal element  200   b,  and second intermediate nodes  354  can align circumferentially with troughs  204   a , 204   b  of the first longitudinal element  200   a  and the second longitudinal element  200   b.    
     The first intermediate branches  310  can each have a thin width  315  about equal to the width  215  of the thin segments  210   a , 210   b  of the longitudinal elements  200   a,    200   b,  and the second intermediate branches  324  can have a thick width  325  about equal to the width  225  of the thick segments  220   a , 220   b  of the longitudinal elements  200   a,    200   b.  The thin first intermediate branches  310  can be positioned circumferentially about half way between thick segments  220   a  of the first longitudinal element  200   a  and the thick segments  220   b  of the second longitudinal element  200   b,  and the thick second intermediate branches  324  can be positioned circumferentially about half way between the thin segments  210   a  of the first longitudinal element  200   a  and the thin segments  210   b  of the second longitudinal element  200   b.  In this manner, longitudinally extending thin and thick segments can be positioned in an alternating fashion around the circumference  120  of the stent  100 . 
     In another example not shown, longitudinal elements  200  can be used in place of intermediate branches  310 , 324 . Referring to  FIG. 2 , and for the sake of visualizing such a geometry, first intermediate nodes  352  can be shaped to join first intermediate branches  310  and second intermediate branches  324  end-to-end each in the shape of a peak of a wave, and the second intermediate nodes  354  can be shaped to join the first intermediate branches  310  and second intermediate branches  324  end-to-end each in the shape of a trough of a wave. Configured thusly, the intermediate branches essentially take on the shape of the longitudinal elements  200 . 
       FIG. 3  is a three-dimensional illustration of an example stent  100  in a bent configuration. The stent  100  can be made up of longitudinal elements  200  spanning the length  110  of the stent  100  from a first open end  112  to a second open end  114 . The longitudinal elements  200  can have alternating flexible segments  210  and rigid segments  220 . The longitudinal elements  200  can be connected by interconnecting members  300  that span the length  110  of the stent  100 , connecting circumferentially adjacent longitudinal elements  200 . The interconnecting members  300  can be made up of branches. At each end  112 ,  114  of the stent  100 , end joining members  150  can connect each end segment of the longitudinal elements  200  to each end branch of the interconnecting members  300 . 
       FIGS. 4 and 5  are a flow diagrams outlining example method steps that can be used in the process of manufacturing a stent. The method steps can be implemented by any of the example means described herein or by any means that would be known to one of ordinary skill in the art. 
     Referring to method  700  outlined in  FIG. 4 , in step  710  an elastic tubing having a circumferential direction and a longitudinal direction can be provided. The elastic tubing can be for example nitinol, nitinol alloy, other memory shape metal, elastic implantable tubing, or other material known in the art. In step  720 , the tubing can be cut to form a first alternating pattern of flexible struts and rigid struts extending in the longitudinal direction, each of the flexible struts being more flexible than each of the rigid struts as measured for each in the longitudinal direction. In step  730  first nodes can be positioned at each intersection of the flexible struts and rigid struts of the first alternating pattern. In step  740 , the tubing can be cut to form first branches such that each of the first branches extends from each of the first nodes. In step  750  the tubing can be cut to form at least one adjacent pattern of flexible struts and rigid struts extending in the longitudinal direction and positioned adjacent to the first alternating pattern in the circumferential direction. In step  760  the first branches can be connected to the at least one adjacent alternating pattern. 
     Referring to method  800  outlined in  FIG. 5 , in step  810  an elastic tubing having a circumferential direction and a longitudinal direction can be provided. The elastic tubing can be for example nitinol, nitinol alloy, other memory shape metal, elastic implantable tubing, or other material known in the art. In step  820 , the tubing can be cut to form a first alternating pattern of flexible struts and rigid struts extending in the longitudinal direction, each of the flexible struts being more flexible than each of the rigid struts as measured for each in the longitudinal direction. In step  830  first nodes can be positioned at each intersection of the flexible struts and rigid struts of the first alternating pattern. In step  840 , the tubing can be cut to form first branches such that each of the first branches extends from each of the first nodes. In step  845 , intermediate branches can be cut such that each intermediate branch extends from a first branch, and such that each intermediate branch has a width less than the width of the first branch from which it extends. In step  850  the tubing can be cut to form at least one adjacent pattern of flexible struts and rigid struts extending in the longitudinal direction and positioned adjacent to the first alternating pattern in the circumferential direction. In step  855 , each of the flexible struts can be cut to have a substantially uniform thin width between a first pair of adjacent nodes and each of the rigid struts can be cut to have a substantially uniform thick width between a second pair of adjacent nodes such that the thin width measures less than the thick width. In step  860  the first branches can be connected to the at least one adjacent alternating pattern. 
     The descriptions contained herein are examples of embodiments of the invention and are not intended in any way to limit the scope of the invention. As described herein, the invention contemplates many variations and modifications of the stent, including alternative shapes for the longitudinal elements, interconnecting members having more or fewer branches, interconnecting members having different geometries, additional or fewer struts, or utilizing any of numerous materials or manufacturing means for the stent, for example. These modifications would be apparent to those having ordinary skill in the art to which this invention relates and are intended to be within the scope of the claims which follow.