Abstract:
A medical device for sympathetic nerve ablation includes a catheter shaft and an expandable member disposed on the catheter shaft. The balloon is configured to be able to shift between an unexpanded configuration and an expanded configuration. The medical device includes an elongate electrode assembly constructed as a flexible circuit and a protective bumper member. The elongate electrode assembly may have an outer edge and may be disposed on an outer surface of the balloon. The protective bumper member may cover at least a portion of the outer edge of the elongate electrode assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §119 to U.S. Provisional Application Ser. No. 61/955,097, filed Mar. 18, 2014, and to U.S. Provisional Application Ser. No. 62/032,778, filed Aug. 4, 2014, the entirety of both of which are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure pertains to medical devices, and methods for using and manufacturing medical devices. More particularly, the present disclosure pertains to medical devices and methods that relate to nerve ablation. 
       BACKGROUND 
       [0003]    A wide variety of intracorporeal medical devices have been developed for medical use, for example, intravascular use. Some of these devices include guidewires, catheters, and the like. These devices are manufactured by any one of a variety of different manufacturing methods and may be used according to any one of a variety of methods. Of the known medical devices and methods, each has certain advantages and disadvantages. There is an ongoing need to provide alternative medical devices as well as alternative methods for manufacturing and using medical devices. 
       SUMMARY 
       [0004]    Medical devices and methods for making and using medical devices are disclosed herein. An example medical device for sympathetic nerve ablation is disclosed. The medical device comprises: 
         [0005]    a catheter shaft; 
         [0006]    an expandable balloon disposed on the catheter shaft, the balloon being capable of shifting between an unexpanded configuration and an expanded configuration; 
         [0007]    an elongate electrode assembly constructed as a flexible circuit, the elongate electrode assembly disposed on an outer surface of the balloon and having an outer edge; and 
         [0008]    a protective bumper member covering at least a portion of the outer edge of the elongate electrode assembly. 
         [0009]    Alternatively or additionally to any of the embodiments above, the protective bumper member comprises a polymeric material. 
         [0010]    Alternatively or additionally to any of the embodiments above, the protective bumper member comprises a light curable adhesive. 
         [0011]    Alternatively or additionally to any of the embodiments above, the protective bumper member is formed of an adhesive having a viscosity greater than about 6000 centiPoise. 
         [0012]    Alternatively or additionally to any of the embodiments above, the bumper member is formed of an adhesive having a viscosity greater than about 10,000 centiPoise. 
         [0013]    Alternatively or additionally to any of the embodiments above, the protective bumper member covers substantially all of the outer edge of the elongate electrode assembly. 
         [0014]    Alternatively or additionally to any of the embodiments above, at least a portion of a bottom side of the elongate electrode assembly is attached to the outer surface of the balloon. 
         [0015]    Alternatively or additionally to any of the embodiments above, the balloon is a non-compliant balloon and the elongate electrode assembly folds and unfolds with the balloon. 
         [0016]    Alternatively or additionally to any of the embodiments above, the balloon is a compliant balloon and the elongate electrode assembly folds and unfolds with the balloon. 
         [0017]    Alternatively or additionally to any of the embodiments above, the balloon comprises polyethyleneterephthalate (PET). 
         [0018]    A medical device for sympathetic nerve ablation is disclosed. The medical device comprises: 
         [0019]    a catheter shaft; 
         [0020]    an expandable member coupled to the catheter shaft, the expandable member being capable of shifting between an unexpanded configuration and an expanded configuration; and 
         [0021]    an elongate electrode assembly constructed as a flexible circuit having a plurality of layers and an outer edge, the elongate electrode assembly disposed on an outer surface of the expandable member; and 
         [0022]    a protective bumper member extending about the outer edge of the flexible circuit. 
         [0023]    Alternatively or additionally to any of the embodiments above, the protective bumper member covers the outer edge and a portion of an outer periphery of the flexible circuit. 
         [0024]    Alternatively or additionally to any of the embodiments above, the protective bumper member comprises a polymeric material. 
         [0025]    Alternatively or additionally to any of the embodiments above, the protective bumper member comprises a light curable adhesive. 
         [0026]    Alternatively or additionally to any of the embodiments above, the protective bumper member is formed of an adhesive having a viscosity greater than about 6000 centiPoise. 
         [0027]    Alternatively or additionally to any of the embodiments above, the protective bumper member is formed of an adhesive having a viscosity greater than about 10,000 centiPoise. 
         [0028]    Alternatively or additionally to any of the embodiments above, the balloon is a non-compliant balloon and the elongate electrode assembly folds and unfolds with the balloon. 
         [0029]    A medical device for sympathetic nerve ablation within a body passageway is disclosed. The medical device comprises: 
         [0030]    a catheter shaft;
       an elongate balloon coupled to the catheter shaft, the balloon being capable of shifting between an unexpanded configuration and an expanded configuration;       
 
         [0032]    a plurality of electrode assemblies each constructed as a flexible circuit having a plurality of layers, the plurality of electrode assemblies being bonded to an outer surface of the balloon, each of the plurality of electrode assemblies including an outer edge; and 
         [0033]    a plurality of protective polymeric bumper members, each of the plurality of protective polymeric bumper members surrounding the outer edge of a corresponding one of the plurality of electrode assemblies. 
         [0034]    Alternatively or additionally to any of the embodiments above, at least some of the plurality of raised protective bumpers are formed of an adhesive having a viscosity greater than about 6000 centiPoise. 
         [0035]    Alternatively or additionally to any of the embodiments above, the balloon is a non-compliant balloon. 
         [0036]    The above summary of some embodiments is not intended to describe each disclosed embodiment or every implementation of the present invention. The Figures, and Detailed Description, which follow, more particularly exemplify these embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0037]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the present disclosure and together with the description, serve to explain the principles of the disclosure. 
           [0038]      FIG. 1  is a schematic view illustrating an exemplary renal nerve ablation system, according to some embodiments of the present disclosure; 
           [0039]      FIG. 2  is a schematic view illustrating an exemplary sympathetic nerve ablation device, in accordance with the present disclosure; 
           [0040]      FIG. 3  is a schematic top view illustrating a flattened view of the sympathetic nerve ablation device of  FIG. 2 ; 
           [0041]      FIG. 4  is a schematic side view illustrating a portion of an electrode assembly including a protective bumper member; 
           [0042]      FIG. 5  is a schematic side view illustrating a portion of an electrode assembly including a protective bumper member; 
           [0043]      FIG. 6  is a schematic side view illustrating a portion of an electrode assembly including a protective bumper member; 
           [0044]      FIG. 7  is a schematic side view of a portion of an elongate electrode assembly; 
           [0045]      FIG. 8  is a schematic side view of a portion of an elongate electrode assembly; 
           [0046]      FIG. 9  is a schematic side view of a portion of an elongate electrode assembly; 
           [0047]      FIG. 10  is a schematic side view of a portion of an elongate electrode assembly; 
           [0048]      FIG. 11  is a schematic side view of a portion of an elongate electrode assembly; 
           [0049]      FIG. 12  is a schematic side view of a portion of an elongate electrode assembly; 
           [0050]      FIG. 13  is a schematic side view of a portion of an elongate electrode assembly; 
           [0051]      FIG. 14  is a schematic top view of a portion of an elongate electrode assembly; 
           [0052]      FIG. 15  is a schematic top view of a portion of an elongate electrode assembly; 
           [0053]      FIG. 16  is a schematic top view of a portion of an elongate electrode assembly; 
           [0054]      FIG. 17  is a schematic top view of a portion of an elongate electrode assembly; 
           [0055]      FIG. 18  is a schematic top view of a portion of an elongate electrode assembly; and 
           [0056]      FIG. 19  is a schematic top view of a portion of an elongate electrode assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0057]    Definitions of certain term are provided below, and these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification. 
         [0058]    All numeric values used herein are assumed to be modified by the term “about,” whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same or substantially the same function or result). In many instances, the terms “about” may include numbers that are rounded to the nearest significant figure. The recitation of numerical ranges by endpoints includes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). 
         [0059]    As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents, unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or”, unless the content clearly dictates otherwise. 
         [0060]    The following detailed description should be read with reference to the drawings in which similar elements in different drawings are identified with the same reference numbers. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention. 
         [0061]    It is noted that references in the specification to “an embodiment”, “some embodiments”, “other embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with one embodiment, it should be understood that such feature, structure, or characteristic may also be used in connection with other embodiments, whether or not explicitly described, unless cleared stated to the contrary. 
         [0062]    Certain treatments may require the temporary or permanent interruption or modification of select nerve function. One exemplary treatment is renal nerve ablation, which is sometimes used to treat conditions related to hypertension and/or congestive heart failure. The kidneys produce a sympathetic response to congestive heart failure, which, among other effects, increases the undesired retention of water and/or sodium. Ablating some of the nerves running to the kidneys may reduce or eliminate this sympathetic function, which may provide a corresponding reduction in the associated undesired symptoms. 
         [0063]    Many nerves (and nervous tissue, such as brain tissue), including renal nerves, run along the walls of, or in close proximity to, blood vessels, and thus can be accessed intravascularly through the walls of the blood vessels. In some instances, it may be desirable to ablate perivascular nerves using a radio frequency (RF) electrode. In other instances, the perivascular nerves may be ablated by other techniques or devices, including application of thermal, ultrasonic, laser, microwave, and other related energy sources to the vessel wall. 
         [0064]      FIG. 1  is a schematic view of an illustrative renal nerve ablation system  10  in situ. In the illustrated embodiment, the system  10  is used to ablate one or more renal nerves of a right kidney K. In the illustrated embodiment, only the right kidney K is shown for purposes of simplicity of explanation, however, the system  10  can be used for both right and left kidneys, and associated renal vasculature, such as the renal artery RA that branches laterally from the abdominal aorta. 
         [0065]    In general, system  10  may include one or more conductive element(s)  12  providing power to renal ablation system  14  disposed within a sheath  16 . Although not shown, a proximal end of conductive element  12  may be connected to a control and power element  18 , which supplies the necessary electrical energy to activate one or more electrodes at or near a distal end of the renal ablation system  10 . The system  10  further includes two or more connectors  20  and  22  that may provide connection between the conductive element  12  and the control and power element  18  through a connective link  24 , which can be a wire, for example. The control and power element  18  may include monitoring elements to monitor parameters, such as power, temperature, voltage, pulse size and/or shape and other suitable parameters as well as suitable controls for performing the desired procedure. The control and power element  18  may control a radio frequency (RF) electrode, which may be configured to operate at a frequency of approximately 460 kHz. It is contemplated that any desired frequency in the RF range may be used, for example, from 450-500 kHz. However, different types of energy outside of the RF spectrum may be used as desired, for example, but not limited to, ultrasound, microwave, and laser technologies. 
         [0066]      FIG. 2  is a schematic view illustrating a portion of an example renal nerve ablation device  26 . In particular, the device  26  includes a catheter shaft  28  having an expandable member  30  coupled to the catheter shaft  28 . In the illustrated embodiment, the expandable member  30  is a balloon; however, those skilled in the art will appreciate that other suitable expandable members, such as members formed at least partially of mesh, etc., can also be used. 
         [0067]    Although not shown, the catheter shaft  28  may have a proximal region that may extend proximally to remain outside of the patient&#39;s body, whereas a distal region having the expandable member  30  is configured to be inserted into the patient&#39;s body. The catheter shaft  28  may also include one or more lumens (not shown) extending between the proximal and distal regions, where the catheter shaft  28  may be adapted to enter a patient&#39;s body. Specifically, the distal region of the catheter shaft  28  may be advanced within the patient&#39;s body to reach a target site. In certain instances, the proximal region of the catheter shaft  28  may include a hub attached thereto for connecting to other diagnostic and/or treatment devices, which provides a port for facilitating other interventions. 
         [0068]    The device further includes several elongate electrode assemblies that may be disposed about an outer surface  32  of the expandable member  30 . Any number of elongate electrode assemblies may be disposed about outer surface  32 . In  FIG. 2 , one elongate electrode assembly  34  may be seen in its entirety, and portions of an elongate electrode assembly  36  and an elongate electrode assembly  38  can be seen. 
         [0069]      FIG. 3  provides a flattened view of outer surface  32  and thus illustrates more of outer surface  32 . As illustrated, device  26  includes elongate electrode assembly  34 , elongate electrode assembly  36 , elongate electrode assembly  38  and elongate electrode assembly  40 . It will be appreciated that device  26  may include more than four elongate electrode assemblies. In some embodiments, device  26  may include fewer than four elongate electrode assemblies. 
         [0070]    In the illustrated embodiment, elongate electrode assembly  34  includes a distal pad  42  and a proximal pad  44 . Elongate electrode assembly  36  includes a distal pad  46  and a proximal pad  48 . Elongate electrode assembly  38  includes a distal pad  50  and a proximal pad  52 . Elongate electrode assembly  40  includes a distal pad  54  and a proximal pad  56 . While not expressly called out, it will be appreciated that each of distal pads  42 ,  46 ,  50  and  54  and each of proximal pads  44 ,  48 ,  52  and  56  include one or more layers in their construction and one or more conductive traces disposed within the one or more layers. 
         [0071]    In some embodiments, device  26  includes one or more bumper members that at least partially cover an edge of one or more of the elongate electrode assemblies. As seen in  FIG. 3 , a protective bumper member  58  surrounds elongate electrode assembly  34 , a protective bumper member  60  surrounds electrode assembly  36 , a protective bumper member  62  surrounds electrode assembly  38  and a protective bumper member  64  surrounds electrode assembly  40 . While each protective bumper member  58 ,  60 ,  62  and  64  is illustrated as extending around a majority of the corresponding elongate electrode assembly  34 ,  36 ,  38  and  40 , respectively, it will be appreciated that in some embodiments protective bumper members  58 ,  60 ,  62  and  64  may instead extend around only a portion of the respective elongate electrode assembly  34 ,  36 ,  38  and  40 . For example, protective bumper member  58  may include a first portion (not illustrated) extending only around distal pad  42  and a second portion (not illustrated) extending only around proximal pad  44 . Furthermore, while the term “protective” is used when describing the protective bumper members  58 ,  60 ,  62  and  64 , this is not intended to be limiting. For example, the protective bumper members  58 ,  60 ,  62  and  64  may provide a number of desirable features in addition to or instead of providing “protection” to, for example, the elongate electrode assembly  34 . Thus, the protective bumper members  58 ,  60 ,  62  and  64  could also be termed “bumpers”, “bumper members”, “edge covers”, “edging”, or the like. 
         [0072]    Each of protective bumper members  58 ,  60 ,  62  and  64  may be formed of a polymer and may help to bond or secure the corresponding elongate electrode assembly  34 ,  36 ,  38  and  40  to outer surface  32 . The protective bumper members  58 ,  60 ,  62  and  64  may also help to cover and protect edges of the elongate electrode assemblies  34 ,  36 ,  38  and  40  in order to help prevent electrode delamination and other possible damage to device  26  upon insertion, delivery to the therapy site, expansion of expandable member  30 , contraction of expandable member  30 , and withdrawal of device  26 . A variety of polymeric materials may be used in forming the protective bumper members  58 ,  60 ,  62  and  64 . It will be appreciated that in some embodiments, protective bumper members  58 ,  60 ,  62  and  64  may each be formed as single layers or as several distinct layers. 
         [0073]    In some embodiments, a polymeric adhesive having a viscosity greater than about 3,000 or 4000 centipoise (cP) may be used. In some embodiments, a polymeric adhesive having a viscosity of greater than about 6,000 cP may be used. In some embodiments, a polymeric adhesive viscosity having a viscosity of greater than about 10,000 cP may be used. 
         [0074]    In some embodiments, it will be appreciated that a desired adhesive viscosity depends, at least in part, upon the curing time of the adhesive. For example, an adhesive having a relative low viscosity may be used as long as the adhesive in question has a relatively fast cure time. Alternatively, an adhesive having a relatively long cure time may be used as long as the adhesive has a relatively high viscosity. In some embodiments, it is desirable to use a polymeric adhesive having a combination of viscosity and cure time that permits formation of a desired protective bumper profile. 
         [0075]    A variety of different polymeric adhesives and other polymeric materials may be used. Illustrative examples include but are not limited to epoxies, acrylics, silicone, polyurethane and cyanoacrylates. In some embodiments, a light curable adhesive may be used. In some embodiments, a light curable adhesive such as those available commercially under the Loctite® name may be used. As an illustrative but non-limiting example, Loctite® 352™ may be used. 
         [0076]    Generally, the polymeric materials selected to form protective bumper members  58 ,  60 ,  62  and  64  may be applied to device  26  using any suitable technique and may be cured using any curing process appropriate for the particular polymeric material. In some instances, the polymeric materials may be selected to provide a tough, flexible bond that is resistant to abrasion, vibration and shock. 
         [0077]      FIGS. 4-6  may be considered as schematic cross-sections taken along line  4 - 4  of  FIG. 3 . Accordingly,  FIGS. 4-6  may be considered as schematically showing various examples of protective bumper member  64 .  FIG. 4  illustrates a version of protective bumper member  64 , referred to here as protective bumper member  66 . Bumper member  66  can be seen as extending over a portion of an elongate electrode assembly  68 . Elongate electrode assembly  68  includes an upper surface  70  and a lower surface  72  that is secured to outer surface  32 . Elongate electrode assembly  68  also includes an outer edge  74  and a corner  76  disposed between upper surface  70  and outer edge  74 . 
         [0078]    In  FIG. 4 , protective bumper member  66  can be seen as completely covering a portion of upper surface  70 , corner  76  and outer edge  74 . Protective bumper member  66  may be considered as including an upper portion  78  covering a portion of upper surface  70  and a lower portion  80  extending away from elongate electrode assembly  68  along outer surface  32 . While it can be seen that outer edge  74  and corner  76  of elongate electrode assembly  68  are well-protected by protective bumper member  66 , in some instances protective bumper member  66  may be larger than optimal. In some instances, if the protective bumper member is too large, it can interfere with apposition of the electrode pads with a vessel wall, negatively impacting therapy efficacy or consistency thereof. In some instances, if the protective bumper member is too large, the protective bumper member can interfere with profile upon delivery. For these reasons,  FIG. 4  may be considered as illustrating a less than optimal bumper member. 
         [0079]    In  FIG. 5 , a protective bumper member  82  includes an upper portion  84  covering a portion of upper surface  70  and a lower portion  86  extending away from elongate electrode assembly  68  along outer surface  32 . It can be seen that although outer edge  74  and corner  76  of elongate electrode assembly  68  are covered by protective bumper member  82 , protective bumper member  82  has a thickness measured at corner  74  that is less than that shown, for example, in  FIG. 4 , but still provides a desired level of protection.  FIG. 5  may be considered as illustrating an optimal bumper member. 
         [0080]    In  FIG. 6 , a protective bumper member  88  includes an upper portion  90  covering a portion of upper surface  70  and a lower portion  92  extending away from elongate electrode assembly  68  along outer surface  32 . It can be seen that upper portion  90  and lower portion  92  are no longer part of a contiguous bumper member, but rather are separate. Accordingly, outer edge  74  and corner  76  are not well-protected by protective bumper member  88 .  FIG. 6  may be considered as illustrating a poor bumper member. 
         [0081]    Several dimensions may be useful in defining protective bumper members, and in defining the relative quality of the protective bumper member. With particular reference to  FIG. 5 , the upper portion of the protective bumper member (covering the upper surface of the elongate electrode assembly) may be considered as having a width R 1  while the lower portion of the protective bumper member (extending along the outer surface of the expandable member) may be considered as having a width R 2 . Other useful dimensions include a maximum thickness R 3  of the upper portion and a maximum thickness R 4  of the lower portion. A thickness R 5 , measured at the corner of the elongate electrode assembly, may also be useful. While  FIGS. 4-6  show protective bumper members in which R 1  and R 2  tend to remain substantially constant, it will be appreciated that in some cases R 1  and/or R 2  may vary. 
         [0082]    It will be appreciated that in some cases, it may be useful to define dimensions R 1 , R 2 , R 3  and R 5  in terms of R 4 , a thickness of the elongate electrode assembly  68 . For example, in some embodiments, R 1  may be 2 to 20 times R 4 . R 2  may be 2 to 20 times R 4 . R 3  may be 1 to 20 times R 4 . R 5  may be 1 to 14 times R 4 . In some instances, R 4  can vary from about 0.03 millimeters (mm) to about 0.07 mm, although in some cases R 4  can be outside of this range, depending on the construction of the elongate electrode assembly  68 . To illustrate, the table below provides illustrative ranges for R 1 , R 2 , R 3  and R 5 , based upon an illustrative value for R 4  of 0.0015 inches (0.0381 mm). 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 Dimension 
                 Range (millimeters) 
               
               
                   
                   
               
             
             
               
                   
                 R1 
                 0.0762-0.762 
               
               
                   
                 R2 
                 0.0762-0.762 
               
               
                   
                 R3 
                 0.0381-0.762 
               
               
                   
                 R5 
                  0.0381-0.5334 
               
               
                   
                   
               
             
          
         
       
     
         [0083]    It will be appreciated that there may be tradeoffs in designing the dimensions of the protective bumper members. Making the protective bumper member generally larger may provide better protection to the edges of the elongate electrode assemblies, but may consume more polymeric materials and may impact flexibility and overall profile of the expandable member  30 . Conversely, making the protective bumper member generally smaller may consume less polymeric material and result in a more flexible, lower profile, expandable member  30  but may not provide as much protection to the elongate electrode assembly. 
         [0084]    In  FIGS. 4 through 6 , the elongate electrode assembly  68  is schematically illustrated as having a rectilinear cross-sectional profile. In some embodiments, the elongate electrode assembly  68  may have a modified edge profile that enhances adhesion, or mechanical anchorage, of the elongate electrode assembly  68  to the outer surface  32  of the expandable member  30  (see  FIG. 2 ). In some embodiments, a modified edge profile may improve adhesion by reducing focal points of stress. A modified edge profile may, in some cases, provide for an increased adhesive surface contact area. 
         [0085]    In some instances, the modified edge profile of the elongate electrode assembly  68  may be formed using any suitable technique. In some embodiments, the modified edge profile may be achieved by building up multiple layers having various dimensions. In some embodiments, manufacturing techniques including but not limited to sanding, scrapping, cutting, grinding, chemical etching, stamping, laser cutting, laser etching and the like may be employed.  FIGS. 7 through 13  provide illustrative but non-limiting examples of modified edge profiles for the elongate electrode assembly  68 . While illustrated without bumper members, it will be appreciated that in some cases the illustrated modified edge profiles may be combined with a bumper member if desired. 
         [0086]      FIG. 7  is a side view of a portion of an elongate electrode assembly  168  disposed on the outer surface  32  of the expandable member  30 . The elongate electrode assembly  168  has a multifaceted outer edge including a first facet  170  that is substantially perpendicular to the outer surface  32  (as illustrated), a second facet  172  that angles upward from the first facet  170  and a third facet  174  that angles downward from the first facet  170 . It can be seen that the third facet  174  forms, in combination with the outer surface  32  of the expandable member  30 , a recessed portion that can help to secure a bumper member (not illustrated) in position, if included. 
         [0087]      FIG. 8  is a side view of a portion of an elongate electrode assembly  268  disposed on the outer surface  32  of the expandable member  30 . The elongate electrode assembly  268  has a multifaceted outer edge including a first vertical (in the illustrated orientation) facet  270 , a second vertical facet  274  and an intervening horizontal facet  272 . The horizontal facet  272  may be considered as being orthogonal to the first vertical facet  270  and/or the second vertical facet  274 . This step-wise profile may reduce stress between the expandable member  30  and the elongate electrode assembly  268 . 
         [0088]      FIG. 9  is a side view of a portion of an elongate electrode assembly  368  disposed on the outer surface  32  of the expandable member  30 . The elongate electrode assembly  368  has a curved outer edge  370  that eliminates what would otherwise be a sharp outer edge. 
         [0089]      FIG. 10  is a side view of a portion of an elongate electrode assembly  468  disposed on the outer surface  32  of the expandable member  30 . The elongate electrode assembly  468  has a multifaceted outer edge including a first vertical facet  470 , a second vertical facet  474  and an intervening horizontal facet  472 . The horizontal facet  472  may be considered as being orthogonal to the first vertical facet  470  and/or the second vertical facet  474 . In this embodiment, the second vertical facet  474  is stepped back from the first vertical facet  470  to form a recess that can, for example, help to hold, or secure, a portion of a bumper member (if included). 
         [0090]      FIG. 11  is a side view of a portion of an elongate electrode assembly  568  disposed on the outer surface  32  of the expandable member  30 . The elongate electrode assembly  568  includes a substantially rectilinear portion  570  and a bulbous portion  572 . In some embodiments, the bulbous portion  572  includes an upper surface  574  that is relatively higher above the outer surface  32  in comparison to an upper surface  576  of the substantially rectilinear portion  570 , with an angled portion  578  transitioning between the upper surface  574  and the upper surface  576 . The bulbous portion  572  also includes a lower surface  580  that stands above the upper surface  32  and transitions to the upper surface  32  via an angled portion  582 . The elongate electrode assembly  568  may reduce stress and provide for improved bumper member adhesion. 
         [0091]      FIG. 12  is a side view of a portion of an elongate electrode assembly  668  disposed on the outer surface  32  of the expandable member  30 . The elongate electrode assembly  668  includes an angled facet  670  that extends downward to the outer surface  32 . In some embodiments, the angled facet  670  reduces stress between the elongate electrode assembly  668  and the outer surface  32  of the expandable member  30 . 
         [0092]      FIG. 13  is a side view of a portion of an elongate electrode assembly  768  disposed on the outer surface  32  of the expandable member  30 . The elongate electrode assembly  768  includes an upper angled facet  770  that extends downward to the outer surface  32 . In some embodiments, as illustrated, the elongate electrode assembly  768  includes a second angled facet  772  that, in combination with an at least substantially vertical facet  774 , forms an interior void  776  that can hold adhesive, thereby providing improved mechanical anchorage of the adhesive to the elongate electrode assembly  768 . 
         [0093]      FIGS. 7-13  provided illustrative but non-limiting examples of modified edge profiles in which the modification impacts an outer edge and upper edge or corner of the elongate electrode assembly. In some embodiments, the elongate electrode assembly can be modified to improve stress/strain performance by cutting or otherwise forming voids that extend into a front face of the elongate electrode assembly.  FIGS. 14-19  provide illustrative but non-limiting examples of elongate electrode assemblies into which voids have been cut or otherwise formed into a front face thereof. It will be appreciated that the examples illustrated in  FIGS. 14-19  may include one or more of the modified edge profiles illustrated in  FIGS. 7-13 . 
         [0094]      FIG. 14  is a schematic top view of a portion of an elongate electrode assembly  868  having an outer edge  870 . As illustrated, a rectilinear void  872  is cut into the outer edge  870 . One or more voids  874  are formed within the elongate electrode assembly  868  but do not extend to the outer edge  870 . The void  874  may have any desired width or length and may be proportional to the dimensions of the elongate electrode assembly  868 . 
         [0095]      FIG. 15  is a schematic top view of a portion of an elongate electrode assembly  968  having an outer edge  970 . As illustrated, a void  972  is cut into the outer edge  970 . The void  972  includes a rectilinear portion  974  and a circular portion  976 . One or more voids  978  are formed within the elongate electrode assembly  968  but do not extend to the outer edge  970 . In some embodiments, the void  978  may include a rectilinear portion  980  and a circular portion  982 . 
         [0096]      FIG. 16  is a schematic top view of a portion of an elongate electrode assembly  1068  having an outer edge  1070 . A void  1072  may be formed within the elongate electrode assembly  1068  but does not extend to the outer edge  1070 . The void  1072  may be positioned at any desired distance from the outer edge  1070 . 
         [0097]      FIG. 17  is a schematic top view of a portion of an elongate electrode assembly  1168  having an outer edge  1170 . A series of circular voids  1172  may be formed within the elongate electrode assembly  1168  but do not extend to the outer edge  1170 . The circular voids  1172  may be positioned at a relative spacing between adjacent circular voids  1172 . The circular voids  1172  may be positioned at any desired distance from the outer edge  1170 . 
         [0098]      FIG. 18  is a schematic top view of a portion of an elongate electrode assembly  1268  having an outer edge  1270 . One or more voids  1272  are cut into the outer edge  1270 . In some embodiments, the void(s)  1272  are T-shaped, having a first rectilinear portion  1274  extending from the outer edge  1270  and a second rectilinear portion  1276  that is orthogonal to the first rectilinear portion  1274 . One or more T-shaped voids  1278  may be formed within the elongate electrode assembly  1268  but do not extend to the outer edge  1270 . The T-shaped void(s)  1278  has a first rectilinear portion  1280  and a second rectilinear portion  1282  that is orthogonal to the first rectilinear portion  1280 . 
         [0099]      FIG. 19  is a schematic top view of a portion of an elongate electrode assembly  1368  having an outer edge  1370 . One or more voids  1372  may be formed within the elongate electrode assembly  1368  but do not extend to the outer edge  1370 . The voids  1372  may be positioned at any desired distance from the outer edge  1370 . 
         [0100]    Catheter shaft  28  and expandable member  30  may be manufactured from various materials, including any suitable biocompatible and compliant materials, such as, but not limited to, polymers, metals, alloys, either in combination or alone. The material(s) employed may be sufficiently stiff to enable use in various lumen diameters, and be sufficiently flexible to maneuver through tortuous and/or stenotic lumens, avoiding any undesirable tissue injuries. To this end, the materials employed may include shape memory materials, such as, but not limited to, Nitinol. Other suitable materials may include polyether block amide, polyurethane, etc. In some embodiments, the material employed may have an insulating property. 
         [0101]    Some examples of suitable metals and metal alloys include stainless steel, such as 304V, 304L, and 316LV stainless steel; mild steel; nickel-titanium alloy such as linear-elastic and/or super-elastic nitinol; other nickel alloys such as nickel-chromium-molybdenum alloys (e.g., UNS: N06625 such as INCONEL® 625, UNS: N06022 such as HASTELLOY® C-22®, UNS: N10276 such as HASTELLOY® C276®, other HASTELLOY® alloys, and the like), nickel-copper alloys (e.g., UNS: N04400 such as MONEL® 400, NICKELVAC® 400, NICORROS® 400, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such as MP35-N® and the like), nickel-molybdenum alloys (e.g., UNS: N10665 such as HASTELLOY® ALLOY B2®), other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten or tungsten alloys, and the like; cobalt-chromium alloys; cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like); platinum enriched stainless steel; titanium; combinations thereof; and the like; or any other suitable material. 
         [0102]    Some examples of suitable polymers may include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, for example, DELRIN® available from DuPont), polyether block ester, polyurethane (for example, Polyurethane 85A), polypropylene (PP), polyvinylchloride (PVC), polyether-ester (for example, ARNITEL® available from DSM Engineering Plastics), ether or ester based copolymers (for example, butylene/poly(alkylene ether) phthalate and/or other polyester elastomers such as HYTREL® available from DuPont), polyamide (for example, DURETHAN® available from Bayer or CRISTAMID® available from Elf Atochem), elastomeric polyamides, block polyamide/ethers, polyether block amide (PEBA, for example available under the trade name PEBAX®), ethylene vinyl acetate copolymers (EVA), silicones, polyethylene (PE), Marlex high-density polyethylene, Marlex low-density polyethylene, linear low density polyethylene (for example REXELL®), polyester, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polytrimethylene terephthalate, polyethylene naphthalate (PEN), polyetheretherketone (PEEK), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), poly paraphenylene terephthalamide (for example, KEVLAR®), polysulfone, nylon, nylon-12 (such as GRILAMID® available from EMS American Grilon), perfluoro(propyl vinyl ether) (PFA), ethylene vinyl alcohol, polyolefin, polystyrene, epoxy, polyvinylidene chloride (PVdC), poly(styrene-b-isobutylene-b-styrene) (for example, SIBS and/or SIBS 50A), polycarbonates, ionomers, biocompatible polymers, other suitable materials, or mixtures, combinations, copolymers thereof, polymer/metal composites, and the like. In some embodiments the sheath can be blended with a liquid crystal polymer (LCP). For example, the mixture can contain up to about 6 percent LCP. 
         [0103]    Although the embodiments described above have been set out in connection with a renal nerve ablation device, those of skill in the art will understand that the principles set out there can be applied to any device where it is deemed advantageous to provide flexibility to the renal nerve ablation device. Conversely, constructional details, including manufacturing techniques and materials, are well within the understanding of those of skill in the art and have not been set out in any detail here. These and other modifications and variations are well within the scope of the present disclosure and can be envisioned and implemented by those of skill in the art. 
         [0104]    Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. It is intended that the specification and examples be considered as exemplary only, and departure in form and detail may be made without departing from the scope and spirit of the present disclosure as described in the following claims.