Abstract:
Interconnects for connecting axially expandable segments of stents are disclosed. The interconnects include a proximal connector, a first arm, a second arm and a distal connector. The connectors secure the interconnect to the adjacent axially expandable members. The first arm and the second arm provide flexible elements of the interconnect to confer a degree of axial flexibility between the segments.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is a Continuation-In-Part Application of co-pending U.S. patent application Ser. No. 11/045,927, filed Jan. 28, 2005, entitled FLEXIBLE CELLS FOR AXIALLY INTERCONNECTING STENT COMPONENTS. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to medical stents and, more particularly, to methods and apparatus which interconnect expandable units within a stent.  
         [0004]     2. Background of the Related Art  
         [0005]     In recent years a corrective procedure, percutaneous transluminal coronary angioplasty, and devices known as balloon angioplasty catheters have been widely used to correct stenotic conditions within arteries, particularly coronary arteries, in a relatively efficient manner. An angioplasty procedure generally includes inserting a deflated balloon, mounted on a catheter, within the affected vessel or artery at the point of a stenosis. The balloon is then inflated to physically force the dilation of the partially occluded vessel.  
         [0006]     Unfortunately, a substantial percentage of patients who have had balloon angioplasty redevelop the stenosis in a relatively short period of time. The reoccurrence of stenosis, termed restenosis, typically becomes evident within 6 months of the angioplasty procedure and may affect 30 to 40 percent of patients. The percentage of patients who have reoccurring stenoses following angioplasty is generally reduced by installing a “scaffolding” device, known as a stent, at the site of the stenosis.  
         [0007]     Stents are generally tubular devices, frequently made of a thin-walled metallic or woven material. Usually, a pattern of apertures, openings or holes is defined around the circumference of the stent along most of the length of the stent. A stent is guided to the stenosis by catheter and expanded to expand the lumen wall and provide support to the lumen wall so as to keep the lumen substantially open. While coronary and other arterial stenoses are common applications for stenting, stents can also be used to treat narrowings in any hollow or tubular organ or body lumen, such as the esophagus, urethra, biliary tract, and the like.  
         [0008]     Stents may be constructed from a variety of materials, such as stainless steel, Elgiloy, Nitinol, shape memory polymers, and the like. They may be formed by a variety of methods. For example, a stent may be formed by etching or cutting the stent pattern from a tube or section of stent material; or a sheet of stent material may be cut or etched according to a desired stent pattern, whereupon the sheet may be rolled or otherwise formed into the desired tubular or bifurcated tubular shape of the stent; or one or more wires or ribbons of stent material may be braided or otherwise formed into the desired shape and pattern.  
         [0009]     Stents are typically provided in two fundamental configurations termed self-expanding stents and balloon expandable stents. Combinations or hybrids of these two fundamental configurations have also been developed that have some characteristics of both self-expandable and balloon expandable stents. Self-expanding stents are generally spring-like devices that are inserted in the body passageway in a contracted state within a delivery catheter or introducer. A self-expanding stent is biased so as to expand upon release from the delivery catheter. When released, the self-expanding stent reconfigures from a contracted to an expanded state. The self-expanding stent tends to increase to a final diameter dependent on the size and configuration of the stent and the elasticity of the body passageway.  
         [0010]     In contrast, a balloon expandable stent requires assistance from a balloon to expand into position. A balloon expandable stent is mounted over a balloon attached to the distal end of a catheter. The balloon expandable stent is guided by the catheter to the proper position at the stenosis. Then, the balloon is inflated to expand the stent radially outward into position. The amount of force applied is at least that necessary to maintain the patency of the body passageway. Once the stent is properly expanded, the balloon is deflated and withdrawn from the patient.  
         [0011]     Stents need to be axially flexible for tracking through tortuous lumen of the human body. In order to make a stent axially flexible, a stent may be made in segments where the segments are connected together by elastic interconnects. The use of interconnects for connecting various segments of the stent has, to some extent, satisfied the need for axial flexibility. However, existing interconnects have certain limitations based upon the mechanisms by which a stent confers a physiological benefit.  
         [0012]     The underlying mechanism for the physiological benefit produced by a stent may be as simple as preventing immediate elastic recoil of the luminal wall and maintaining a large luminal cross-section for a few days after angioplasty. Continuous support by the stent along the luminal wall may be important. In addition, stent surfaces are frequently coated with various therapeutic compounds that prevent restenosis or have other beneficial effects. However, the surface area between stent segments in stents incorporating interconnects is relatively small and the resulting gaps between stent segments may become sites of restenosis perhaps due to the decreased support of the lumen by the stent over the gaps between stent segments or due to the decrease in surface area having a therapeutic coating biased against the lumen over the gaps between stent segments.  
         [0013]     It would, therefore, be a significant advance in the art to provide interconnects that will enable the stent to navigate through tortuous bodily lumen and to conform to tortuous bodily lumen when expanded while providing sufficient surface areas to prevent gaps between stent segments.  
       SUMMARY OF THE INVENTION  
       [0014]     Apparatus and methods in accordance with the present invention may resolve many of the needs and shortcomings discussed above and will provide additional improvements and advantages as will be recognized by those skilled in the art upon review of the present disclosure.  
         [0015]     The present invention provides a stent composed of radially expandable segments, where the radially expandable segments are connected by flexible interconnects. In various embodiments, the expandable stent of the present invention may be self-expandable upon deployment, may be expanded by enlarging an expandable balloon positioned within the stent, or may be of the hybrid type. The stent according to the present invention can be described based on a cylindrical coordinate system where the stent defines a longitudinal axis passing along the length of the stent and a radial axis normal to the longitudinal axis.  
         [0016]     Embodiments of a stent according to the present invention include a plurality of radially expandable segments interconnected by a series of axially flexible interconnects. The radially expandable segments may be configured to support or otherwise contact the walls of a body lumen. The radially expandable segments may be configured from a single strand extending radially around the longitudinal axis of the radially expandable segment or may be formed in a wide variety of alternative radially expandable configurations. The radially expandable segments may generally expand so as to be symmetric in a radial plane. In other variations, the radially expandable segments may be unsymmetric or of biased symmetry in the radial plane. A radially expandable segment may have a constant cross-section along the axis of the stent or a variable cross-section along the axis of the stent and there may be variations between the different segments that compose the stent.  
         [0017]     Adjacent radially expandable segments are connected by a plurality of flexible interconnects. These flexible interconnects are primarily configured to flex or compress in the axial direction parallel to the axis of the stent. The interconnects do not expand in the curvilinear plane defined by the circumference of the stent upon expansion of the stent. Rather, the interconnects expand or contract axially so as to allow articulation of the expandable segments of the stent so as to allow the stent to navigate through a curved lumen or to allow the stent to be deployed within a curved lumen. Upon expansion of the stent, the interconnects are designed to provide additional support to the body lumen and also to provide additional surface area for the elution of therapeutic agents.  
         [0018]     The interconnects are placed around the circumference of a distal radially expandable segment and the circumference of a proximal radially expandable segment so as to link the distal and proximal radially expandable segments. The interconnects generally include a first arm and a second arm designed to flex so as to allow axial expansion or axial compression as the radially expandable segments articulate in response to a curved lumen.  
         [0019]     The first arm and the second arm may be symmetric or may be differentially configured as required to confer desired flexural characteristics. The first arm and the second arm are secured between a proximal connector and a distal connector. The proximal connector is secured to the proximal end of the first arm and the second arm and to a proximal radially expandable segment so as to communicate compressive or expansive forces between the first arm, the second arm, and the proximal radial expandable segment. The distal connector is secured to the distal end of the first arm and the second arm and to a distal radially expandable segment so as to communicate compressive or expansive forces between the first arm, the second arm, and the distal radial expandable segment.  
         [0020]     Typical designs for interconnects according to the present invention include various curved as well as angular configurations of the first arm and the second arm that may be expandable and compressible in the axial direction but not in the radial direction.  
         [0021]     Stents according to the present invention feature an absence of potential tissue snagging structures. The expandable segments are able to articulate with respect to one another, which enables the stent to pass through otherwise tortuous passageways. The stents of the present invention are efficiently and easily produced using laser etching or chemical etching techniques and are amenable to good quality control at a relatively low cost. Other features and advantages of the invention will become apparent from the following detailed description, from the figures, and from the claims.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]      FIG. 1  illustrates a perspective view of an exemplary embodiment of an expandable stent in accordance with the present inventions;  
         [0023]      FIG. 2  illustrates a side view of an exemplary embodiment of a stent in accordance with the present inventions in an unexpanded configuration positioned over a balloon of a balloon catheter within a bodily lumen of a patient which is shown in cross-section;  
         [0024]      FIG. 3  illustrates a side view of an exemplary embodiment of a stent in accordance with the present inventions in an at least partially expanded configuration positioned over a balloon of a balloon catheter within a bodily lumen of a patient which is shown in cross-section;  
         [0025]      FIG. 4  illustrates a plan view of an embodiment of a stent in accordance with the present inventions, showing the stent in a relaxed planar configuration;  
         [0026]      FIG. 5  illustrates a plan view of an embodiment of a stent in accordance with the present inventions, showing the stent in a planar configuration bent to illustrate the expansion and compression of the interconnects;  
         [0027]      FIG. 6  illustrates an enlarged plan view of an exemplary embodiment for an interconnect in accordance with the present inventions;  
         [0028]      FIG. 7  illustrates an enlarged plan view of another exemplary embodiment for an interconnect in accordance with the present inventions;  
         [0029]      FIG. 8  illustrates an enlarged plan view of another exemplary embodiment for an interconnect in accordance with the present inventions;  
         [0030]      FIG. 9  illustrates an enlarged plan view of another exemplary embodiment for an interconnect in accordance with the present inventions;  
         [0031]      FIGS. 10A, 10B , and  10 C illustrate an enlarge plan view of an exemplary embodiment for an interconnect in accordance with the present inventions in a relaxed, a compressed and an extended position, respectively;  
         [0032]      FIGS. 11A, 11B , and  11 C illustrate an enlarge plan view of another exemplary embodiment for an interconnect in accordance with the present inventions in a relaxed, a compressed and an extended position, respectively;  
         [0033]      FIGS. 12A, 12B , and  12 C illustrate an enlarge plan view of another exemplary embodiment for an interconnect in accordance with the present inventions in a relaxed, a compressed and an extended position, respectively;  
         [0034]      FIGS. 13A, 13B , and  13 C illustrate an enlarge plan view of another exemplary embodiment for an interconnect in accordance with the present inventions in a relaxed, a compressed and an extended position, respectively;  
         [0035]      FIGS. 14A, 14B , and  14 C illustrate an enlarge plan view of another exemplary embodiment for an interconnect in accordance with the present inventions in a relaxed, a compressed and an extended position, respectively; and  
         [0036]      FIGS. 15A, 15B , and  15 C illustrate an enlarge plan view of another exemplary embodiment for an interconnect in accordance with the present inventions in a relaxed, a compressed and an extended position, respectively. 
     
    
       [0037]     All Figures are illustrated for ease of explanation of the basic teachings of the present invention only; the extensions of the Figures with respect to number, position, relationship and dimensions of the parts to form the preferred embodiment will be explained or will be within the skill of the art after the following description has been read and understood. Further, the exact dimensions and dimensional proportions to conform to specific force, weight, strength, and similar requirements for various applications will likewise be within the skill of the art after the following description has been read and understood.  
         [0038]     Where used in various Figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms “top,” “bottom,” “right,” “left,” “forward,” “rear,” “first,” “second,” “inside,” “outside,” and similar terms are used, the terms should be understood to reference only the structure shown in the drawings and utilized only to facilitate describing the illustrated embodiments. Similarly, when the terms “proximal,” “distal,” and similar positional terms are used, the terms should be understood to reference the structures shown in the drawings as they will typically be utilized by a physician or other user who is treating or examining a patient with an apparatus in accordance with the present invention.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0039]     The figures generally illustrate embodiments of a stent  10  including aspects of the present inventions. The particular exemplary embodiments of the stent  10  illustrated in the figures have been chosen for ease of explanation and understanding of various aspects of the present inventions. These illustrated embodiments are not meant to limit the scope of coverage but instead to assist in understanding the context of the language used in this specification and the appended claims. Accordingly, many variations from the illustrated embodiments may be encompassed by the appended claims.  
         [0040]     The present inventions provide stents  10  and associated methods. In accordance with the present inventions, a stent  10  will include two or more radially expandable segments  12  interconnected by an axially flexible interconnect  14 . Stents  10  in accordance with the present inventions may be positioned and expanded within a lumen of a patient. Stents  20  in accordance with the present inventions may provide enhanced flexibility and increased surface area for purposes of drug elution and/or support of a lumen wall. In one aspect, stents  10  in accordance with the present inventions may be radially expanded with a balloon  16 .  
         [0041]     As generally illustrated throughout the Figures, stents  10  generally include two or more radially expandable segments  12  interconnected by an interconnect  14 . The interconnect  14  is typically configured primarily for axial expansion and/or compression along the longitudinal axis  300  of stent  10 . The stent  10  generally defines a longitudinal axis  300  along the length of the stent  10 . The stent  10  further includes a proximal end  110  and a distal end  210  which, in the illustrated embodiments, are defined primarily for purposes of description. Other stents  10  incorporating aspect of the present inventions may include a proximal end  110  and a distal end  210  that are functionally distinct without departing from the scope of the present inventions. For exemplary purposes, stent  10  has been illustrated as a balloon expandable stent  10  including a balloon  16  extending through a lumen  18  defined by the stent  10 . In another aspect, the stent  10  may be configured as a self expanding stent  10  or a hybrid of self expanding and balloon expandable stent  10  as will be recognized by those skilled in the art. The radially expandable segments  12  are configured to radially expand after insertion into a lumen.  
         [0042]     The radially expandable segments  12  may be configured to support or otherwise contact the walls of a bodily lumen of a patient. The radially expandable segments  12  may be configured from a single strand  20  extending radially around the longitudinal axis  300  at a desired distance as is generally illustrated in the figures for exemplary purposes or may be formed in a wide variety of alternative radially expandable configurations as will be recognized by those skilled in the art. The strand  20  is generally illustrated with a linear portion  22  which extends parallel to and along the longitudinal axis  300  of the stent  10 . A proximal loop  24  turns the strand  20  distally along the longitudinal axis  300  at a proximal end of the radially expandable segment  12 . A distal loop  26  turns the strand  20  proximally along the longitudinal axis  300  at the distal end of the radially expandable segment  12 . The radially expanding units  12  have been illustrated as generally expanding within a direction perpendicular to the longitudinal axis  300  of stent  10  for exemplary purposes. Upon review of the present disclosure, those skilled in the art will recognize variations of the expandable unit that may expand radially at an angle which is not perpendicular to the longitudinal axis  300 .  
         [0043]     Adjacent radially expandable segments  12  are connected to one another by interconnects  14 . The interconnects  14  are configured to be axially expandable along the longitudinal axis  300  of stent  10 . In one aspect, the interconnects  14  may be configured to be axially compressible along the longitudinal axis  300  of stent  10 . The radially expandable segments  12  within the stent  10  may also contact or be biased against the walls of a bodily lumen to support or otherwise contact the bodily lumen. As illustrated for exemplary purposes, the interconnects  14  may be symmetrically positioned about the longitudinal axis  300  of the stent  10 . In other aspects, the interconnects  14  may be asymmetrically positioned about the longitudinal axis  300  to provide the desired flex characteristics or other characteristics to a stent  10 .  
         [0044]     The interconnects  14  generally include a first arm  34  and a second arm  36  secured between a proximal connector  44  and a distal connector  46 . The first arm  34  and the second arm  36  are generally configured to flex for purposes of axial expansion and/or compression of the interconnect  14 . In one aspect, the axial expansion and/or compression of the interconnects  14  may permit the bending of the stent  10  along the longitudinal axis  300  such that at least a portion of the longitudinal axis  300  is curvilinear. The proximal connector  44  is secured to the proximal ends of the first arm  34  and second arm  36  to communicate compressive or expansive forces between the first arm  34 , second arm  36  and the proximal radial expandable unit  12 . The proximal connector  44  may be integrally formed with, welded to, adhesively bonded to or otherwise secured to the proximal ends of the first arm  34  and second arm  36  as will be recognized by those skilled in the art upon review of the present disclosure. The proximal connector  44  may extend linearly, when in a relaxed state, for a distance between the proximal end of the first arm  34  and second arm  36  and the point of connection to the proximal radially expanding segment  12 . The distal connector  46  is secured to the distal ends of the first arm  34  and second arm  36  to communicate compressive or expansive forces between the first arm  34 , second arm  36  and the distal radial expandable unit  12 . The distal connector  46  may be integrally formed with, welded to, adhesively bonded to or otherwise secured to the distal ends of the first arm  34  and second arm  36  as will be recognized by those skilled in the art upon review of the present disclosure. The distal connector  46  may extend linearly, when in a relaxed state, for a distance between the distal ends of the first arm  34  and second arm  36  and the point of connection to the distal radially expanding segment  12 .  
         [0045]     In one aspect, the first arm  34  and the second arm  36  may be symmetrical about a central axis  302  extending between the proximal connector  44  and the distal connector  46 . In another aspect, the first arm  34  and second arm  36  may be differentially configured, such as by size shape or materials, to confer desired flex characteristics to the stent  10 . The proximal connector  44  connects the interconnect  14  to a proximally positioned radially expandable segment  12 . The proximal connector  44  may be integrally formed with, welded to, adhesively bonded to or otherwise secured to a proximally positioned radially expandable segment  12  as will be recognized by those skilled in the art upon review of the present disclosure. The distal connector  46  connects the interconnect  14  to a distally positioned radially expandable segment  12 . The distal connector  46  may be integrally formed with, welded to, adhesively bonded to or otherwise secured to a distally positioned radially expandable segment  12  as will be recognized by those skilled in the art upon review of the present disclosure. For purposes of the present disclosure, the radially expandable segment  12  positioned proximal to an interconnect  14  along the longitudinal axis  300  may be referred to as a proximal radially expandable segment  12 . Further, the radially expandable segment  12  positioned distal to an interconnect  14  along the longitudinal axis  300  may be referred to as a distal radially expanding unit  12  for purposes of claiming the present inventions for purposes of the present disclosure.  
         [0046]      FIG. 1  particularly illustrates an exemplary embodiment of a stent  10  in accordance with the present inventions. As illustrated, stent  10  includes four radially expandable segments  12  interconnected by a plurality of interconnects  14  symmetrically distributed about a longitudinal axis  300  for exemplary purposes. Each radially expandable segment  12  is configured from a strand  20  extending radially around the longitudinal axis  300 . For exemplary purposes, the strand  20  is illustrated as substantially equidistant from the longitudinal axis  300  over the length of strand  20 . The strand  20  is shown with a linear portion  22  extending parallel to the longitudinal axis  300  of the stent  10 . A proximal loop  24  turns the strand  20  distally along the longitudinal axis  300  at a proximal end of the radially expandable segment  12 . A distal loop  26  turns the strand  20  proximally along the longitudinal axis  300  at the distal end of the radially expandable segment  12 . The interconnects  14  are shown attached to the radially expandable segments  12  at the proximal loops  24  of the distal expandable units  12  and at the distal loops  26  of the proximal expandable units  12  for exemplary purposes.  
         [0047]      FIGS. 2 and 3  illustrate an exemplary embodiment of a stent  10  in accordance with the present inventions in a substantially un-expanded and at least partially expanded position, respectively. The stent  10  is illustrated as fitted over a balloon  16  of a balloon catheter  40 . The stent  10  is also shown generally positioned within a portion of an artery  50  which is partially occluded by a stenosis  52 . As illustrated in  FIG. 3 , once the stent  10  is appropriately located in the lumen of the artery  50 , preferably spanning the stenosis  52 , the radially expandable segments  12  of stent  10  can be expanded radially outward by inflating the balloon  16  of the balloon catheter  40 . As balloon  16  expands, the stent  10  is brought into contact with and may alter the shape of the stenosis  52 . After the radially expandable segments  12  of the stent  10  are fully expanded, the balloon  16  may be deflated and the balloon catheter  40  removed from the patient. Typically, with the expanded stent  10  positioned within the patient, the patency may be at least partially restored in the artery  50 .  
         [0048]      FIGS. 4 and 5  show plan views of an exemplary embodiment of a stent  10  in accordance with the present inventions in a planar configuration for purposes of illustration.  FIG. 4  illustrates a stent  10  in accordance with the present inventions, showing the stent  10  in a relaxed configuration.  FIG. 5  illustrates a stent  10  in accordance with the present inventions showing the stent  10  in a configuration where the stent  10  is bent along the longitudinal axis  300  to illustrate the expansion and compression of the interconnects  14  positioned about the periphery of the stent  10 . Radially expandable segments  12  are shown connected by interconnects  14 . Each of the interconnects  14  includes a proximal connector  34  which is secured to a proximal radially expandable segment  12  and a distal connector  36  which is secure to a distal radially expandable segment  12 . A first arm  34  and a second arm  36  are secured between the proximal connector  34  and the distal connector  36 . Interconnects  14  are configured to expand or contract in the axial direction, but not in the radial direction.  FIG. 5  particularly illustrates the varying expansion of interconnects  14  about the periphery of a stent  10  as the stent  10  is flexed along its longitudinal axis  300 . For illustrative purposes, the interconnects  14  have been labeled  14   a  through  14   e  in order of a substantially fully extended position to substantially relaxed position. Upon review of the present disclosure, those skilled in the art will recognize the implications on the expansion of the interconnects  14  upon the circularization of the planar illustrated embodiment of  FIGS. 4 and 5 .  
         [0049]     FIGS.  6  to  9  illustrate exemplary embodiments for interconnects  14  in accordance with the present inventions. The illustrated interconnects  14  include a proximal connector  44 , a first arm  34 , a second arm  36  and a distal connector  46 . The first arm  34  and the second arm  36  are configured to enhance the flexibility of the stent  10  along the longitudinal axis  300  of the stent  10 . In one aspect, the enhanced flexibility in accordance with the present inventions may permit the flexing of the stent  10  along its longitudinal axis without the deformation of the lumen defined by the stent  10 . As illustrated, a central axis  302  may extend between the proximal connector  44  and the distal connector  46 . Central axis  302  is typically substantially parallel to longitudinal axis  300 . At least a portion of a linear distance of the proximal connector  44  and the distal connector  46  are illustrated extending along the central axis  302  for exemplary purposes. The first arm  34  and the second arm  36  in the illustrated embodiments are substantially symmetrical to one another about the central axis  302 . The first arm  34  and the second arm  36  may lie substantially within a curved plane defined by the outer surface of the radially expandable segments  12 . The first arm  34  may include one or more linear sections  54 , curved sections  56  and angled transitions  58  to define a flexing region along at least a portion of the first arm  34 . The linear sections  54 , curved sections  56  angle transitions  58  and curved transitions  60  generally extend from the central axis  302  within the plane defined by the outer surface of the radially expandable segments  12 . The second arm  36  may include one or more linear sections  64 , curved sections  66  and angled transitions  68  to define a flexing region along at least a portion of the second arm  36 . The linear sections  64 , curved sections  66 , angle transitions  68  and curved transitions  70  generally extend from the central axis  302  in the opposite direction of the linear sections  54 , curved sections  56 , angled transitions  58  and curved transitions  60  of the first arm  34 . The linear sections  64 , curved sections  66 , angle transitions  68  and curved transitions  70  generally lie within the plane defined by the outer surface of the radially expandable segments  12 . The curved portions are typically defined as concave or convex relative to the central axis  302 .  
         [0050]     As particularly illustrated in  FIG. 6  for exemplary purposes, the first arm  34  extends distally from a proximal end secured to the proximal connector  44  and defines a convex curved section  56  up to a first angled transition  58  followed by a concave curved section  56  up to a second angled transition  58  followed by a second convex curved section  56  and terminating at the distal connector  46 . The second arm  36  is illustrated as substantially symmetrical about the central axis  302  to the first arm  34  for exemplary purposes. Particularly, the second arm  36  extends distally from a proximal end secured to the proximal connector  44  and defines a convex curved section  66  up to a first angled transition  68  followed by a concave curved section  66  up to a second angled transition  68  followed by a second convex curved section  66  and terminating at the distal connector  46  and terminating at the distal connector  46 .  
         [0051]     As particularly illustrated in  FIG. 7  for exemplary purposes, the first arm  34  extends distally from a proximal end secured to the proximal connector  44  and defines a first linear section  54  extending perpendicular from the central axis  302  up to a first angled transition  58  followed by a second linear section extending parallel to the central axis  302  up to a second angle transition  58  followed by a third linear section  54  extending toward the central axis  302  followed by a third angled transition  58  followed by a fourth linear section  54  extending away from the central axis  302  up to a fourth angled transition  58  followed by a fifth linear section  54  extending parallel to the central axis  302  up to a fifth angled transition  58  followed by a sixth linear section  54  extending perpendicular to the central axis  302  and terminating at the distal connector  46 . The second arm  36  is illustrated as substantially symmetrical about the central axis  302  to the first arm  34  for exemplary purposes. Particularly, the second arm  36  extends distally from a proximal end secured to the proximal connector  44  and defines a first linear section  64  extending perpendicular from the central axis  302  up to a first angled transition  68  followed by a second linear section extending parallel to the central axis  302  up to a second angle transition  68  followed by a third linear section  64  extending toward the central axis  302  followed by a third angled transition  68  followed by a fourth linear section  6  extending away from the central axis  302  up to a fourth angled transition  68  followed by a fifth linear section  64  extending parallel to the central axis  302  up to a fifth angled transition  68  followed by a sixth linear section  64  extending perpendicular to the central axis  302  and terminating at the distal connector  46 .  
         [0052]     As particularly illustrated in  FIG. 8  for exemplary purposes, the first arm  34  extends distally from a proximal end secured to the proximal connector  44  and defines a first linear section  54  extending perpendicular from the central axis  302  up to a first angled transition  58  followed by a second linear section extending toward the central axis  302  up to a second angle transition  58  followed by a third linear section  54  extending away from the central axis  302  followed by a third angled transition  58  followed by a fourth linear section  54  extending toward from the central axis  302  up to a fourth angled transition  58  followed by a fifth linear section extending away from the central axis  302  up to a fifth angled transition  58  followed by a sixth linear section extending perpendicular to the central axis  302  and terminating at the distal connector  46 . The second arm  36  is illustrated as substantially symmetrical about the central axis  302  to the first arm  34  for exemplary purposes. Particularly, the second arm  36  extents distally from a proximal end secured to the proximal connector  44  and defines a first linear section  64  extending perpendicular from the central axis  302  up to a first angled transition  68  followed by a second linear section extending toward the central axis  302  up to a second angle transition  68  followed by a third linear section  64  extending away from the central axis  302  followed by a third angled transition  68  followed by a fourth linear section  64  extending toward from the central axis  302  up to a fourth angled transition  68  followed by a fifth linear section extending away from the central axis  302  up to a fifth angled transition  68  followed by a sixth linear section extending perpendicular to the central axis  302  and terminating at the distal connector  46 .  
         [0053]     As particularly illustrated in  FIG. 9  for exemplary purposes, the first arm  34  extends distally from a proximal end secured to the proximal connector  44  and defines a convex curved section  56  up to a first curved transition  60  followed by a second convex curved section  56  up to a second curved transition  60  followed by a second convex curved section  56  and terminating at the distal connector  46 . The second arm  36  is illustrated as substantially symmetrical about the central axis  302  to the first arm  34  for exemplary purposes. Particularly, the second arm  36  extends distally from a proximal end secured to the proximal connector  44  and defines a convex curved section  66  up to a first curved transition  70  followed by a concave curved section  66  up to a second curved transition  70  followed by a second convex curved section  66  and terminating at the distal connector  46  and terminating at the distal connector  46 .  
         [0054]      FIGS. 10A  to  15 C illustrate additional variations for symmetrical configurations of interconnects  14  in accordance with the present inventions. Each variation is illustrated in relaxed, at least partially compressed, and at least partially extended configurations for exemplary purposes.  
         [0055]      FIGS. 10A  to  10 C illustrate an exemplary interconnect  14  having curved sections  56 ,  66  defining a first flexible lobe and a second flexible lobe axially along the interconnect  14 .  FIG. 10A  illustrates the exemplary interconnect  14  in a substantially relaxed position.  FIG. 10B  illustrates the exemplary interconnect  14  in an at least partially compressed position.  FIG. 10C  illustrates the exemplary interconnect  14  in an at least partially expanded position.  
         [0056]      FIGS. 11A  to  11 C illustrate another exemplary interconnect  14  including linear sections  54 ,  64  and angled transitions  58 ,  68  defining a saw tooth pattern axially along the interconnect  14 .  FIG. 11A  illustrates the exemplary interconnect  14  in a substantially relaxed position.  FIG. 11B  illustrates the exemplary interconnect  14  in an at least partially compressed position.  FIG. 11C  illustrates the exemplary interconnect  14  in an at least partially expanded position.  
         [0057]      FIGS. 12A  to  12 C illustrate another exemplary interconnect  14  curved sections  56 ,  66  defining a single flexible lobe.  FIG. 12A  illustrates the exemplary interconnect  14  in a substantially relaxed position.  FIG. 12B  illustrates the exemplary interconnect  14  in an at least partially compressed position.  FIG. 12C  illustrates the exemplary interconnect  14  in an at least partially expanded position.  
         [0058]      FIGS. 13A  to  13 C illustrate another exemplary interconnect  14  having curved sections  56 ,  66  and curved transitions  60 ,  70  defining a first flexible lobe and a second flexible lobe axially along the interconnect  14  in an alternative configuration to the lobes illustrated in  FIGS. 10A  to  10 C.  FIG. 13A  illustrates the exemplary interconnect  14  in a substantially relaxed position.  FIG. 13B  illustrates the exemplary interconnect  14  in an at least partially compressed position.  FIG. 13C  illustrates the exemplary interconnect  14  in an at least partially expanded position.  
         [0059]      FIGS. 14A  to  14 C illustrate another exemplary interconnect  14  having curved sections  56 ,  66  and angled transitions  60 ,  70  defining a first flexible lobe, a second flexible lobe and a third flexible lobe axially along the interconnect  14 .  FIG. 14A  illustrates the exemplary interconnect  14  in a substantially relaxed position.  FIG. 14B  illustrates the exemplary interconnect  14  in an at least partially compressed position.  FIG. 14C  illustrates the exemplary interconnect  14  in an at least partially expanded position.  
         [0060]      FIGS. 15A  to  15 C illustrate another exemplary interconnect  14  having curved sections  56 ,  66  and angled transitions  60 ,  70  defining a first flexible lobe, a second flexible lobe and a third flexible lobe axially along the interconnect  14  in an alternative configuration to the lobes illustrated in  FIGS. 14A  to  14 C.  FIG. 15A  illustrates the exemplary interconnect  14  in a substantially relaxed position.  FIG. 15B  illustrates the exemplary interconnect  14  in an at least partially compressed position.  FIG. 15C  illustrates the exemplary interconnect  14  in an at least partially expanded position.  
         [0061]     Stents  10  in accordance with the present inventions may be manufactured using a wide variety of techniques that will be recognized by those skilled in the art upon review of the present disclosure. One exemplary method can include providing a segment of cylindrical walled material from which the stent  10  will be made. Depending upon the type of stent  10  to be made, any of the materials herein discussed or other materials that are well known in the art may be used depending upon the particular characteristics desired. The stent  10  is prepared by removal of material from the cylindrical wall, which material will not be part of the stent  10  to be formed. This may occur by mechanically cutting away material. Preferably, however, the cutting or material removal is automated. A computer aided laser-cutting device is one option. A computer aided water-jet cutting device is another option. In each case, software that guides the cutting tool will assure that only the material, which is intended to be removed, is in fact removed. Another removal technique is chemical etching of the cylinder wall. The portion of the cylinder to be retained as a part of the stent is protected from exposure to the chemical etching process. For example, in the case of a metallic stent, an etching agent might be one of a number of acids, which are well known in the art. A chemically protective agent, for example, a hydrophobic coating, such as a wax, may be applied over the entire exterior surface of the cylinder. Next, the protective coating is removed mechanically using a computer aided water jet cutting device, or the like, where etching is desired. If greater surface thickness is desired, wider areas need to be protected. If thinner surface thickness is desired, then narrower areas are protected. Alternatively, other means of selectively applying protective coatings, for example, photographically based methods, which are well known in the etching arts, may be used. Finally, the partially protected cylinder is immersed in an acid bath. Etching occurs throughout the interior cylinder surface but only at selected portions of the exterior. When the etching has proceeded to the extent that the etching from the exterior and interior surface has fully removed appropriate portions of the cylinder, the piece is removed from the acid. Next, the protective coating is removed. If the coating is wax, the wax may be removed by heating or by a wax solvent, which does not further affect the metal. Chemical etching is a suitable production method for low volume production. Higher volume production is believed to be more suitably achieved through the use of computer aided laser etching. The availability of using wider or narrower surface thickness, as well as different tubing wall thickness is considered an important means of obtaining stiffness or easier deformability in the desired devices of the present invention. Generally, thin wall tubing is believed to be preferable, but not absolutely required.  
         [0062]     An alternate material from which expandable stents  10  in accordance with the present invention may be prepared is, without limit, stainless steel, particularly type 316 stainless steel, more preferably type 316 L or 316 Lvm stainless steel, but gold, platinum, e tantalum, silver and the like are also believed to be suitable. Other materials may include various polymers, composite materials and other materials as will be recognized by those skilled in the art upon review of the present disclosure. Some features for which the material may be selected are deformability and the ability to hold the shape once deformed. It may also desirable that the stent  10  be made from radiopaque materials or include radiopaque coatings over at least a portion of the stent  10 . Stents  10  made of stainless steel which have a thickness of 0.005 inch are typically radiopaque, however, stents having lesser thicknesses, such as stents made specifically for use in coronary arteries which often requires thicknesses less than 0.005 inch (often for example, about 0.003 inch) may need to be coated with a radiopaque material such as 24 carat gold to a thickness of about 0.0002 inch. In addition, other coatings including specific functional agents may also be employed to address issues such as blood clotting (e.g. heparin and the like) or reduction in the amount of intimal hyperplasia and resulting restenosis (e.g. cytotoxic drugs, gene therapy agents and the like). Methods to coat metal prostheses to make them radiopaque or to minimize the risks due to blood clotting are well known in the art and any of these methods and the devices resulting from the use of these methods are all envisioned within the scope of the present invention.  
         [0063]     It is understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this disclosure is illustrative only and changes may be made in detail, especially in matters of shape, size and arrangement of parts, within the principles of the present invention, to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.