Patent Publication Number: US-8540697-B2

Title: Push/pull wire anchor

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 12/479,193, filed Jun 5, 2009, which is a continuation of U.S. application Ser. No. 11/149,079, filed on Jun. 9, 2005, now U.S. Pat. No. 7,553,305 to Honebrink et al., which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     A push-pull wire anchor and in particular a push-pull wire anchor in a deflectable catheter for transmitting pushing and pulling forces without failure of the catheter. 
     BACKGROUND 
     It is often difficult to provide reliable couplings between a push-pull wire and the deflectable distal end portion of a deflectable catheter. Welding or soldering the push-pull wire to a marker band in the deflectable distal end portion can anneal a portion of the wire adjacent to the weld. The annealed portion of the wire is sometimes weakened relative to the rest of the push-pull wire. When the push-pull wire experiences the stress of repeated pushing and pulling from an actuator the wire may fracture in the annealed region. Additionally, the marker band extends remotely from the push-pull wire around the catheter body. Pushing and pulling forces can tear the pull ring apart through shearing forces thereby freeing the push-pull wire to undesirably move within the catheter. 
     Often, the deflectable distal end portion of the catheter is in a deflected position within a curved vessel when the push-pull wire fractures. If pushing forces are applied to the push-pull wire after fracture, the fractured end of the push-pull wire may puncture the sidewall of the deflected catheter. Further, if the catheter is in a substantially non-deflected position and pushing forces are applied to deflect the catheter, the fractured end of the push-pull wire may puncture the distal end of the catheter. 
     Moreover, fracturing the wire prevents transmission of pushing and pulling forces to the deflectable distal end portion. Failure of the push-pull wire can complicate a medical procedure. For instance, the catheter must be withdrawn through curving vasculature, possibly in a deflected position created prior to fracture of the push-pull wire. The deflected catheter can snag within the vasculature and complicate the extraction. Further, the catheter must be exchanged with another deflectable catheter and the vasculature traversed again to complete the medical procedure. 
     In other examples, the push-pull wire is retained within a deflectable distal end portion by adhesives and the like. Assembling a catheter with an adhered push-pull wire is complex and requires hollowing out a portion of the catheter and injecting the adhesive into the hollowed out portion of the catheter to couple the push-pull wire with the deflectable distal end portion. In still other examples, the push-pull wire is adhered to the catheter with a hardened distal end portion. The push-pull wire is potted (i.e., covered on its distal and side surfaces) with the adhesive that forms the distal end portion. Compressive stresses from the push-pull wire can dislodge the distal end portion and cause failure of the catheter. Additionally, the adhesives used to form the distal end portion create a hard structure that has little or no deformability and can therefore be traumatic when engaged against the soft tissues of vasculature and organs. 
     What is needed is a push-pull wire anchor that overcomes the shortcomings of previous designs. What is further needed is a push-pull wire anchor that substantially prevents fracture of the push-pull wire and puncturing of a catheter by a fractured push-pull wire. 
     SUMMARY 
     A deflectable catheter for a catheter assembly includes a catheter body including a deflectable distal end portion. A flexible element (e.g., a push-pull wire) including a flexible element distal portion extends along at least a portion of the deflectable distal end portion. At least one anchor, such as a skirt extends at least part way around the flexible element distal portion and is coupled with the flexible element. In one option, the skirt is integral to the flexible element distal portion. An encapsulant is coupled between the skirt and the deflectable distal end portion. The encapsulant is adapted to transmit pushing and pulling forces from the skirt to the deflectable distal end portion, and the encapsulant forms at least a portion of an outer surface of the deflectable distal end portion. The tension strength and compression strength of the flexible element and the at least one skirt are at least as strong as the encapsulant tension strength and compression strength. The skirt includes at least one recess (e.g., holes, corrugations, grooves or the like) dimensioned and configured to receive the encapsulant, in yet another option. 
     Several options for the deflectable catheter follow. In one option, at least one weld couples the flexible element distal portion to the deflectable distal end portion, and the at least one weld is distal to the at least one skirt. In another option, the at least one skirt includes a flared portion. 
     The flared portion includes at least one recess (e.g., hole, corrugation or the like) optionally. 
     The at least one skirt includes, in yet another option, a clamp substantially surrounding the flexible element distal portion. The clamp is crimped at a plurality of points along the clamp, optionally. 
     In another option, at least one of the skirt and the flexible element distal portion include at least one projection. At least one of the skirt and the distal portion include at least one recess sized and shaped to receive the at least one projection, optionally. In yet another option, the at least one projection extends from the skirt and engages against the flexible element distal portion substantially immobilizing the at least one skirt relative to the flexible element. In still another option, the skirt includes knurling, brazing dots or the like. 
     A method for making a deflectable catheter includes positioning a flexible element along a catheter liner. A distal portion of the flexible element extends along at least a portion of a deflectable distal end portion of the catheter liner. At least one skirt is coupled to the distal portion, and the at least one skirt extends at least part way around the flexible element distal portion. The method further includes positioning an encapsulant around at least the flexible element distal portion and the deflectable distal end portion. The encapsulant is squeezed around the flexible element distal portion and the skirt, and the encapsulant forms at least a portion of a sidewall of the deflectable distal end portion and at least the skirt is within the sidewall. The encapsulant is adapted to transmit pushing and pulling forces from the at least one skirt to the deflectable distal end portion. The tension strength and compression strength of the flexible element and the at least one skirt are at least as strong as the encapsulant tension strength and compression strength. 
     Several options for the method follow. In one option, the method includes substantially preventing a puncture of the encapsulant by the flexible element (e.g., the encapsulant grasps the skirt and the skirt is coupled to the flexible element). In another option, a marker band is coupled substantially adjacent to the deflectable distal end portion. The marker band is distal relative to the skirt. The flexible element distal portion is welded to the marker band. The method includes, in yet another option, substantially preventing fracture of the flexible element adjacent to the marker band. 
     In another option, the skirt includes a clamp, and the clamp is deformed to grasp the flexible element distal portion. The clamp is crimped at a plurality of points along the clamp, optionally. The method includes, in yet another option, engaging a projection extending from at least one of the skirt and the flexible element distal portion against the other of the skirt and the distal portion. In still another option, engaging the projection includes seating the projection within at least one recess sized and shaped to receive the projection, wherein the recess is formed in at least one of the skirt and the flexible element distal portion. Optionally, the method includes deforming at least one of the flexible element and the skirt with the projection to form the recess. 
     The above described catheter allows for deflection of a deflectable distal end portion while substantially preventing fracture of a flexible element. Pushing and pulling forces from the flexible element are transmitted through the skirt to the encapsulant and the catheter liner at the deflectable distal end portion of the catheter. The skirt anchored in the encapsulant facilitates deflection of the deflectable distal end portion through transmission of the pushing and pulling forces. In one option, the skirt is integral to the flexible element distal portion. Where the flexible element distal portion is not coupled to a marker band optionally, the skirt and the flexible element are disposed along the catheter body proximal to a marker band used to see the tip of the catheter body during procedures (e.g., with fluoroscopy). Proximally positioning the skirt provides additional space to include features, for instance flush openings and the like, positioned between the skirt and marker band. 
     The flexible element and the skirt have tension and compression strengths at least as great as the tension and compression strengths of the encapsulant to substantially reduce fracture of the flexible element. Optionally, the catheter body is adapted to fail before failure of the flexible element and the skirt, and puncturing of the catheter body is thereby substantially prevented by a fractured element. In another option, the skirt is coupled to the flexible element distal portion without a weld. Fracturing of the flexible element is thereby substantially reduced because stress is not applied to a weakened annealed region. Additionally, the skirt is localized around the flexible element without extending remotely around the deflectable distal end portion. The skirt thus provides improved strength and durability against failure through shearing. Moreover, because the skirt is localized substantially adjacent to the flexible element pushing and pulling forces are not distributed around the catheter body. The deflectable distal end portion thus experiences an improved deflection response with the concentrated pushing and pulling of the flexible element. 
     In another option, the skirt cooperates with the marker band coupled to the flexible element distal portion. The marker band is coupled to the flexible element distally relative to the skirt. The skirt acts as a supplementary anchor and distributes pushing and pulling forces between the marker band and itself. Fracturing of the flexible element adjacent to the marker band (e.g., the annealed region near a weld) is substantially reduced because the pushing and pulling forces are distributed between the skirt and the marker band. Additionally, where the flexible element distal portion does fracture adjacent the marker band, the skirt embedded in the encapsulant acts to substantially immobilize the fractured flexible element and substantially prevent puncturing of the catheter body. Moreover, the skirt facilitates continued use of the catheter with a fractured flexible element because the skirt continues to function as an anchor and transmits pushing and pulling forces to the deflectable distal end portion. 
     Additionally, the encapsulant is squeezed around the catheter liner to easily form an outer surface and sidewall of the catheter body and grasp the skirt. In one option, the skirt is in the sidewall and thereby provides a larger moment to the deflectable distal end portion because it is positioned remotely from the center of the catheter body. As described above, the encapsulant flows around the skirt and, when hardened, transmits tension and compression forces to the deflectable distal end portion while also acting as the outer surface of the catheter body. Complex manufacturing procedures including drilling and/or forming a pocket for an anchor and injecting an adhesive over the anchor are thereby avoided. Further, the skirt is retained along the catheter body and the distal end therefore does not house the skirt and/or the flexible element in a hard tip. In one option, the distal end of the catheter body thereby has a soft atraumatic tip. 
     These and other embodiments, aspects, advantages, and features of the present invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art by reference to the following description of the invention and referenced drawings or by practice of the invention. The aspects, advantages, and features of the invention are realized and attained by means of the instrumentalities, procedures, and combinations particularly pointed out in the appended claims and their equivalents. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of one example of a catheter in a first deflected position. 
         FIG. 1B  is a perspective view of the catheter in a non-deflected position. 
         FIG. 1C  is a perspective view of the catheter in a second deflected position. 
         FIG. 2  is a perspective view of one example of the deflectable distal end portion. 
         FIG. 3  is a cross-sectional view of one example of a catheter assembly. 
         FIG. 4A  is a partial sectional view of another example of a catheter assembly. 
         FIG. 4B  is a partial sectional view of another example of a catheter assembly. 
         FIG. 4C  is a perspective view of one example of an anchor. 
         FIG. 4D  is a partial sectional view of another example of a catheter assembly. 
         FIG. 5A  is a perspective view of another example of an anchor. 
         FIG. 5B  is a perspective view of yet another example of an anchor. 
         FIG. 6  is a cross-sectional view of yet another example of a catheter assembly. 
         FIG. 7  is a cross-sectional view of still another example of a catheter assembly. 
         FIG. 8A  is a perspective view of one example of a catheter assembly. 
         FIG. 8B  is a perspective view of one example of an anchor. 
         FIG. 8C  is a perspective view of another example of an anchor. 
         FIG. 8D  is a perspective view of yet another example of an anchor. 
         FIG. 9  is a cross-sectional view of one example of a catheter assembly. 
         FIG. 10  is a cross-sectional view of another example of a catheter assembly. 
         FIG. 11  is a partial sectional view of another example of the deflectable distal end portion. 
         FIG. 12  is a block diagram illustrating one example of a method for making a catheter assembly. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents. 
       FIGS. 1A , B, C illustrate a deflectable catheter assembly  100 , where  FIG. 1A  illustrates the deflectable catheter assembly  100  in one articulated position, and  FIG. 1C  illustrates the catheter assembly in another articulated orientation.  FIG. 1B  illustrates the deflectable catheter assembly  100  in an unarticulated position. The deflectable catheter assembly  100  includes a catheter body  110  and a handle assembly  150  that houses actuating mechanisms for deflecting the catheter body  110 . The handle assembly  150  allows for the selectable deflection of a deflectable distal end portion  102  of the catheter body  110  into any number of disparate orientations. One example of the handle assembly  150  is described in co-pending application Ser. No. 10/179,633, assigned to Enpath Medical, Inc., entitled ARTICULATING HANDLE FOR A DEFLECTABLE CATHETER, which is incorporated herein by reference. As shown in  FIGS. 1A , B, C the actuating mechanism includes a wheel  104 . The wheel  104  is rotated to deflect the deflectable distal end portion  102  into the orientations shown in  FIGS. 1A , C. In another option, the handle assembly  150  includes a slide, knob, pull ring or the like to facilitate deflection of the deflectable distal end portion  102 . 
     As shown in  FIGS. 2-10 , the catheter body  110  includes a flexible element  200 , for instance a push-pull wire or the like. Optionally, the flexible element  200  is constructed with, but is not limited to steel, polymers or the like. The flexible element  200  is coupled between the actuating mechanisms in the handle assembly  150  ( FIG. 1 ) and the deflectable distal end portion  102 . As shown in  FIGS. 1A , C, when tension or compression is applied to the flexible element  200  (e.g., using the wheel  104 ), corresponding pushing or pulling forces are experienced by the deflectable distal end portion  102  causing the deflectable distal end portion  102  to curve in predetermined directions. The distal end portion  102  is deflected, in one option, to traverse vasculature with the catheter assembly  100 . 
     Referring again to  FIGS. 1A , B, C, the catheter body  110  includes an elongate tubular construction that is flexible yet substantially non-compressible along its length. The deflectable catheter body  110  extends from a proximal end  106  to the deflectable distal end portion  102 . The deflectable distal end portion  102 , in one option, is adapted to be disposed within a patient. As described above, at the proximal end  106  the deflection of the deflectable catheter body  110  is controlled with the handle assembly  150  containing the actuator mechanism coupled to the flexible element  200  ( FIG. 2 ) and the wheel  104 . The distal end portion  102  is deflected to traverse various branch vessels with the catheter assembly  100  ( FIGS. 1A and 1C ). 
       FIG. 2  illustrates a partial cut-away of one example of the deflectable distal end portion  102  of the catheter body  110  shown in  FIGS. 1A , B, C. The catheter body  110  includes a catheter liner  202  having a catheter lumen  204  extending therein (e.g., the catheter liner  202  defines the catheter lumen  204 ). The catheter lumen  204  is sized and shaped to receive a variety of instruments, fluids or the like. In one option, the catheter lumen  204  extends through the catheter body  110  to the handle assembly  150  ( FIG. 1 ). The distal end of the catheter liner  202  forms at least a portion of the deflectable distal end portion  102 . The catheter liner  202  includes, but is not limited to, flexible materials with sufficient strength and wear resistance for use in the catheter assembly  100 . In one example, the catheter liner  202  includes a polymer such as polytetrafluoroethylene used under the trademark TEFLON® registered to E.I. Du Pont De Nemours and Company. 
     A flexible element duct  206  is positioned along the catheter liner  202 , in one option. The flexible element duct  206  is substantially parallel to the catheter liner  202  and extends along at least a portion of the catheter liner  202 , in another option. For instance, as shown in  FIG. 2 , the flexible element duct  206  extends from an intermediate portion  207  of the catheter body  110  (e.g., proximal to the deflectable distal end portion  102 ) toward the proximal end  106  adjacent to the handle assembly  150  ( FIGS. 1A , B, C). In another example, the distal end  208  of the flexible element duct  206  is proximal to a distal tip  210  of the catheter body  110 . The flexible element duct  206  includes an actuator lumen sized and shaped to receive the flexible element  200  (e.g., the flexible element duct  206  defines the actuator lumen). In one option, the flexible element  200  is slidably coupled with the flexible element duct  206  to facilitate transmission of pushing and pulling forces for deflection of the deflectable distal end portion  102 . 
     In one option, a distal portion  201  of the flexible element  200  extends from the distal end  208  of the flexible element duct  206  toward the distal tip  210  of the catheter body  110 . In another option, the flexible element distal portion  201  extends from the distal end  208  of the duct  206  toward a marker band  212 . The marker band  212  extends around the catheter liner  202 . Optionally, the marker band  212  is coupled to the catheter liner  202  with crimping, adhesives, overmolding or the like. The marker band  212  is fluoroscopic in still another option, facilitating viewing of the deflectable catheter distal end portion  102  during procedures (e.g., when the catheter body  110  is within vasculature). As shown in one example of the catheter body  110  in  FIG. 2 , the flexible element distal portion  201  is optionally coupled to the marker band  212 . The distal portion  201  and the marker band  212  are coupled together with, but not limited to, welds, adhesives, mechanical fasteners or the like. 
     The catheter liner  202 , flexible element duct  206 , flexible element  200 , and the marker band  212  are surrounded by an encapsulant  214 . In one option, the encapsulant  214  includes a biocompatible metal, polymer and the like. In one example, the encapsulant  214  includes a poly-ether-block amide compound such as PEBAX® a trademark registered to the Atofina Corporation. The components of the catheter body  110  are encapsulated with the encapsulant  214 , optionally, by heating the encapsulant to a molten state and squeezing it around catheter liner  202 , flexible element duct  206 , flexible element  200  and the marker band  212 . The encapsulant  214  flows around the components, grasps them, and solidifies when cooled to form the catheter body  110 . The encapsulant  214  forms a sidewall  215  and at least a portion of an outer surface  217  of the catheter body  110  surrounding the catheter lumen  204 . At least the flexible element duct  206  and the flexible element  200  are contained within the encapsulant  214  and outside of the catheter lumen  204 . The encapsulant  214  forms the outer surface  217  of at least a portion of the deflectable distal end portion  102 , optionally. The encapsulant provides a smooth outer surface  217  and is easily positioned around the catheter body  110  (e.g., heated and squeezed around the catheter body  110 ). Complex manufacturing procedures including drilling and/or forming a pocket for an anchor and injecting an adhesive over the anchor are thereby avoided. 
     In another option, the encapsulant  214  is squeezed around the catheter liner  202  and the other components with shrink tubing  216 . The shrink tubing  216  contracts when exposed to heat and squeezes the molten encapsulant  214  around the catheter liner  202  and the other components. The shrink tubing  216  ensures the encapsulant  214  provides a smooth consistent cross-sectional geometry for the catheter body  110 . Optionally, the shrink tubing  216  is constructed with, but not limited to, polymers, such as Fluoro Ethylene Propylene. In yet another option, the shrink tubing  216  is split and removed from the catheter body  110  after the encapsulant  214  has solidified. As shown in  FIG. 2 , the shrink tubing  216  remains coupled around the encapsulant  214 . 
     Optionally, the catheter body  110  includes a stiffening member embedded within the encapsulant, such as a braided member  218 . In one option, the braided member  218  includes a stainless steel braid. The stiffening member facilitates rotation of the deflectable distal end portion  102  from the proximal end  106 . Additionally the stiffening member also assists in preventing the catheter body  110  from collapsing. In another option, the stiffening member extends from the proximal end  106  to the deflectable distal end portion  102 . The stiffening member extends form the proximal end  106  to the intermediate portion  207  of the catheter body  110 , in yet another option. In this option, at least a portion of the deflectable distal end portion  102  is free of the stiffening member thereby enhancing the deflection capability of the distal end portion  102 . 
       FIG. 2  illustrates one example of an anchor, such as a skirt  220  disposed around the distal portion  201  of the flexible element  200 . The skirt  220  is a separate feature from the marker band  212 . Optionally, the skirt  220  is proximal relative to the marker band  212 . The skirt  220 , in one option, is integral to the flexible element  200 . In another option, the skirt  220  is coupled to the flexible element  200 , for example by crimping, disposing projections within recesses, overmolding or the like. The skirt  220  is thereby substantially immobilized along the flexible element  200 . In yet another option, the skirt  220  partially extends around the flexible element distal portion  201 . In one example, the skirt  220  extends around the flexible element distal portion  201  approximately 180 degrees. In another example, the skirt  220  extends further (e.g., all the way) or less around the flexible element distal portion  201 . 
     The skirt  220  provides a larger profile along the flexible element  200  than the element  200  itself. The profile of the skirt  220  allows the encapsulant  214  to grasp the skirt  220  and thereby easily couple with the flexible element distal portion  201  to allow transmission of pushing and pulling forces to the deflectable distal end portion  102 . The skirt  220  anchors the flexible element distal portion  201  within the encapsulant  214 . Pushing and pulling forces are thereby transmitted from the skirt  220  through the encapsulant  214  and to the catheter liner  202  facilitating deflection of the deflectable distal end portion  102 . The encapsulant  214  forms the outer surface  217  of at least a portion of the deflectable distal end portion  102 , optionally. In yet another option, the encapsulant  214  forms the sidewall  215  of the deflectable distal end portion  102  and the skirt  220  is retained within the sidewall  215  and adjacent to the outer surface  217 . Positioning the skirt  220  within the sidewall  215  and adjacent to the outer surface  217  allows for an increased moment to be applied for deflection of the deflectable distal end portion  102  because the skirt  220  and the flexible element distal portion  201  are positioned remotely from the longitudinal center of the catheter body  110 . Additionally, in still another option, the skirt  220  is fully encapsulated to further enhance transmission of pushing and pulling forces to the deflectable distal end portion  102 . Further, the skirt  220  is retained along the catheter body  110 , in an option, thereby allowing the distal tip  210  to have an atraumatic (i.e., deformable) surface for engaging with vasculature and organs. 
     As shown in  FIGS. 4-8 , the skirt  220  includes, optionally, additional features (e.g., knurling, projections, grooves, or the like) to further enhance the engagement of the skirt  220  with the encapsulant  214 . In still another option, the skirt  220  is coupled to the catheter liner  202  with adhesives, mechanical fasteners, or the like, thereby facilitating transmission of pushing and pulling forces to the deflectable distal end portion  102 . 
     In another option, where the catheter body includes the marker band  212 , as shown in  FIG. 2 , the encapsulant grasps the skirt  220 , the marker band  212  and the catheter liner  202 . The pushing and pulling forces from the flexible element  200  are transmitted in part from the skirt  220  to the encapsulant  214  and the catheter liner  202  to deflect the catheter body  110 . Additionally, pushing and pulling forces are transmitted from the flexible element  200  to the marker band  212 , and from the marker band  212  to the encapsulant  214  and the catheter liner  202 . In this example, the skirt  220  acts as a supplementary anchor to the marker band  202  and distributes the pushing and pulling forces between the skirt  220  and the marker band  212 . This decreases the stresses on the coupling between the marker band  212  and the flexible element distal portion  201  and substantially prevents failure of the flexible element distal portion  201  adjacent to the marker band  212  (e.g., the region of the flexible element that is annealed from a weld or other treatment that weakens the element). Because the skirt  220  is proximal relative to the marker band  212 , the skirt  220  substantially prevents puncturing of the catheter body  110  with a fractured flexible element  200  that fails near the marker band  212  (e.g., where the element  200  is annealed adjacent a weld or other means of coupling between the element  200  and the marker band  212 ). The skirt  220  transmits pushing forces to the deflectable distal end portion  102  and substantially prevents longitudinal movement of the fractured flexible element  200  that could otherwise puncture the catheter body  110  and cause injury to surrounding vasculature. Additionally, the skirt  220  allows for at least limited deflection of the catheter body  110  after fracture, facilitating completion of a procedure or removal of the catheter body  110  from vasculature. Moreover, the skirt  220  provides a profile that is localized around the flexible element  200  to minimize shearing stresses on the skirt  220  and enhance the lifespan of the skirt  220  while facilitating deflection of the deflectable distal end portion  102  and immobilization of a fractured flexible element. 
       FIG. 3  shows one example of the skirt  220  coupled along the flexible element distal portion  201 . The skirt  220  is at least partially surrounded by the encapsulant  214  and substantially immobilized in the encapsulant  214 . Similar to the example shown in  FIG. 2 , the skirt  220  cooperates with the encapsulant  214  to couple the flexible element distal portion  201  to the deflectable distal end portion  102 . The marker band  212  is encapsulated as well, but not otherwise coupled to the flexible element  200 . The skirt  220  is a separate feature from the marker band  212 , and relatively proximal to the band  212 . Pushing and pulling forces are thereby transmitted through the skirt  220  to the encapsulant  214  to deflect the distal end portion  102  as shown in  FIGS. 1A , C. 
     The skirt  220 , shown in  FIG. 3 , is constructed with a deformable material, for instance metals, such as steel, aluminum or the like. In one option, the skirt  220  acts as a clamp and is deformed around the flexible element distal portion  201  by crimping. The skirt  220  includes a crimped portion  300  that engages against the flexible element distal portion  201  and couples the skirt  220  to the distal portion  201 . Crimping the skirt  220  to the distal portion  201  substantially immobilizes the skirt  220  relative to the flexible element  200 . Crimping the skirt  220  around the flexible element distal portion  201  substantially reduces the likelihood of fracturing the flexible element  200  with pushing and pulling forces. The skirt  220  is not coupled to the flexible element  200  with a weld or other means, and therefore there is no weakened annealed region along the flexible element  200 . The strength of the flexible element  200  (e.g., tensile and compression strengths) is thereby consistently maintained along the length of the flexible element  200 . The skirt  220  and the flexible element  200  have tension and compression strengths at least as great as the tension and compression strengths of the encapsulant  214  and thereby substantially reduce fracture of the flexible element  200 . Optionally, the catheter body  110  ( FIGS. 1A-C  and  2 ) is adapted to fail before failure of the flexible element  200  and the skirt  220 , thereby substantially preventing puncture of the catheter body  110  by a fractured flexible element  200 . In another option, the skirt  220  includes metals, polymers and the like. Optionally, the skirt  220  is coupled to the flexible element distal portion  201  with adhesives, overmolding and the like. 
     The skirt  220  includes projections  302 , for instance non-crimped segments of the skirt  220 , sized and shaped to extend from the flexible element distal portion  201 . The projections  302  are securely grasped by the encapsulant  214  and anchored therein to firmly couple the skirt  220  and the flexible element  200  to the deflectable distal end portion  102 . In one example, as shown in  FIG. 3 , the encapsulant  214  fills a space defined by the projections  302  to firmly anchor the skirt within the encapsulant. For instance, the projections  302  form a flared conical geometry extending away from the crimped portion  300  of the skirt  220  that receives the encapsulant therein. Pushing and pulling forces are transmitted from the flexible element  200  to the skirt  220  and the projections  302  are securely grasped by the encapsulant  214 . The pushing and pulling forces are transmitted from the skirt  220  and the projections  302  through the encapsulant  214  to the deflectable distal end portion  102 . The skirt  220  thereby pushes and pulls the deflectable distal end portion  102  to deflect the distal end portion  102  as desired. 
       FIGS. 4A , B, D illustrate examples of skirts  400 A, B, D coupled around the flexible element distal portion  201  extending outside the flexible element duct  206 . In one option, the skirts  400 A, B, D are integral to the flexible element distal portion  201 . In another option, the skirts  400 A, B, C are coupled to the distal portion  201  of the flexible element  200  by crimping, adhesives, overmolding or the like. Where the skirts  400 A, B, D are crimped along the flexible element distal portion  201 , the skirts  400 A, B, D are crimped in a similar manner as skirt  220  ( FIG. 2 ). 
     The skirt  400 A shown in  FIG. 4A  has an outer surface  402  including surface roughening, texturing, features or the like, such as knurling  404 . The knurling  404  provides additional features for the encapsulant  214  to grasp and firmly anchor the skirt  400 A to the deflectable distal end portion  102 . The knurling  404  assists in substantially immobilizing the skirt  400 A within the encapsulant  214 . Pushing and pulling forces are thereby readily transmitted through the skirt  400 A to deflect the distal end portion  102  through the encapsulant  214 . In one option, where the flexible element distal portion  201  is welded to the marker band  212  ( FIG. 2 ), the knurling  404  enhances the immobilization of the skirt  400 A and assists in substantially preventing a fractured flexible element  200  from puncturing the catheter body  110  ( FIG. 1 ). 
     The knurling  404  is formed along the skirt  400 A by molding, crimping, or the like. In one option, the knurling  404  along the skirt  400 A is formed with a crimping tool having a working surface with corresponding recesses. When the skirt  400 A is crimped with the tool the skirt outer surface  402  assumes a configuration corresponding to the crimping tool (i.e., the knurling  404  is in a pattern corresponding to the recesses). In one option, the knurling  404  is formed on the skirt  400 A without crimping the skirt  400 A to the flexible element distal portion  201 . In another option, the skirt  400 A is crimped around the distal portion  201  after forming the knurling  404 . The skirt  400 A is adhered, overmolded or the like to couple the skirt  400 A to the distal portion  201 , in yet another option. The knurling  404  is formed on the skirt  400 A and the skirt is crimped around the distal portion  201  in one step, optionally. 
       FIG. 4B  illustrates a skirt  400 B similar in some respects the skirt  400 A shown in  FIG. 4A . Skirt  400 B includes ridges  406  formed along the outer surface  402  of the skirt  400 B. As with the knurling  404  ( FIG. 4A ), the ridges  406  provide additional features for the encapsulant  214  to grasp and firmly anchor the skirt  400 B to the deflectable distal end portion  102 . Optionally, where the flexible element  200  is welded to the marker band  212 , the ridges  406  enhance the immobilization of the skirt  400 B and assist in substantially preventing a fractured flexible element from puncturing the catheter body  110  (See  FIG. 2 ). In one option, the ridges  406  are formed along the skirt  400 B by molding, crimping, or the like. In another option, the skirt  400 B is crimped adhered, overmolded or the like to couple the skirt  400 B to the flexible element  200 . 
       FIG. 4C  illustrates a skirt  400 C including recesses, for instance, corrugations  410 . The corrugations  410  provide features for the encapsulant  214  ( FIG. 2 ) to flow into and enhance the grasp of the encapsulant on the skirt  400 C. The encapsulant  214  and the skirt  400 C cooperate to anchor the flexible element distal portion  201  ( FIG. 2 ) in the deflectable distal end portion  102  ( FIG. 2 ). The skirt  400 C, in one option, has an annular shape as shown in  FIG. 4C  and the corrugations  410  extend around the annular perimeter of the skirt  400 C. The corrugations  410  facilitate transmission of pushing and pulling forces through the skirt  400 C to the encapsulant  214  to deflect the distal end portion  102 . 
     The skirt  400 C is stamped, in one option, to create the corrugations  410 . In another option, the skirt  400 C is formed with the corrugations  410  prior to crimping the skirt  400 C to the flexible element distal portion  201  ( FIG. 2 ). The skirt  400 C includes a flexible element lumen  412 . In one option, the flexible element distal portion  201  is inserted into a non-corrugated portion  412  of the skirt  400 C and the non-corrugated portion  412  is crimped to couple the skirt  400 C with the distal portion  201 . In another option, the flexible element distal portion  201  is inserted into the flexible element lumen  412  and the skirt  400 C is stamped to form the corrugations  410  and couple the skirt  400 C to the flexible element distal portion  201 . In yet another option, the flexible element distal portion  201  extends through the skirt  400 C and is welded to the marker band  212  ( FIG. 2 ). The corrugations  410  increase the immobilization of the skirt  400 C and substantially prevent fracturing of the flexible element  200  ( FIG. 2 ). The skirt  400 C prevents a fractured flexible element  200  from puncturing the catheter body  110 . 
       FIG. 4D  illustrates a skirt  400 D. The outer surface  402  of the skirt  400 D includes recesses  408 . The recesses  408  provide additional features for the encapsulant  214  to flow into and firmly anchor the skirt  400 D to the deflectable distal end portion  102 . The recesses  408  thereby enhance transmission of pushing and pulling forces through the skirt  400 D to deflect the distal end portion  102 . Additionally, where the flexible element distal portion  201  is welded to the marker band  212  ( FIG. 2 ) in one option, the recesses  408  increase the immobilization of the skirt  400 D and substantially prevent a fractured flexible element from puncturing the catheter body  110  ( FIG. 2 ). Optionally, the recesses  408  include openings extending through the skirt  400 D. 
     The recesses  408  are formed along the skirt  400 D by molding, crimping, stamping, drilling, etching, or the like. In one option, the recesses  408  along the skirt  400 D are formed with a crimping tool having a working surface with bosses corresponding to the pattern of the recesses  408 . When the skirt  400 D is crimped with the tool the skirt outer surface  402  assumes a configuration corresponding to the crimping tool (i.e., the recesses  408  are in a pattern corresponding to the bosses). As described above for the skirt  400 A, optionally, the skirt  400 D is crimped to form the recesses  408  and couple the skirt  400 D to the flexible element distal portion  201 . In another option, the skirt  400 D is crimped to form the recesses  408  and crimped again to couple the skirt  400 D to the flexible element  200 . In yet another option, the skirt  400 D is adhered, overmolded or the like to couple the skirt  400 D to the flexible element  200 . 
       FIGS. 5A , B show examples of skirts  500 A, B including recesses  502  dimensioned and configured to receive encapsulant  214  ( FIG. 2 ). Referring now to  FIG. 5A , during forming of the deflectable distal end portion  102  ( FIG. 1 ) the encapsulant  214  flows into the recesses  502  and immobilizes the skirt  500 A within the encapsulant  214 . The recesses  502  allow the encapsulant  214  to grasp the skirt  500 A and facilitate transmission of pushing and pulling forces to the deflectable distal end portion  102 . In one option, the recesses  502  are formed by drilling holes in a pattern along a portion of the skirt  500 A. Optionally, the recesses  502  are formed by stamping, etching or the like. As shown in  FIG. 5B , additional recesses  502  are formed in the skirt  500 B. The larger number of recesses  502  allow for additional penetration of the encapsulant  214  ( FIG. 2 ) and enhance the immobilization of the skirt  500 B. 
     The skirt  500 A is coupled to the flexible element distal portion  201  ( FIG. 2 ) by inserting the flexible element distal portion  201  at least partially through a flexible element lumen  506 . In one option, a portion  504  of the skirt  500 A, which does not have recesses, is crimped around the flexible element distal portion  201 . Crimping the portion  504  provides a strong coupling between the skirt  500 A and the flexible element distal portion  201 . In another option, the entire skirt  500 A is crimped around the flexible element distal portion  201 . The skirt  500 A is coupled with the flexible element distal portion  201  so the portion  504  is proximal relative to the recesses  502  and the distal tip  210  of the catheter body  110  ( FIG. 1 ), optionally. In still another option, the skirt  500 A is coupled so the recesses  502  are proximal relative to the distal tip  210  and the non-recessed portion  504 . The skirt  500 B, shown in  FIG. 5B , is coupled to the flexible element distal portion  201  in a similar manner as described above. The skirts  500 A, B are constructed with, but not limited to metals, in one option. For instance, the skirts  500 A, B include stainless steel. 
       FIG. 6  shows another example of a skirt  600  embedded within the encapsulant  214 . In the example shown in  FIG. 6 , the deflectable distal end portion  102  includes the distal portion  201  of the flexible element  200  extending from the flexible element duct  206 . The skirt  600  is coupled along the flexible element distal portion  201 . As shown, the flexible element distal portion  201  is not coupled with the marker band  212 . In another option, the distal portion  201  is coupled to the marker band  212  ( FIG. 2 ), for instance, with a weld. 
     The skirt  600  acts as a clamp and is deformable. In one option, the skirt  600  includes, but is not limited to, metals such as steel, aluminum or the like. In another option, the skirt  600  extends part way around the distal portion  201  of the flexible element  200 . The skirt  600  extends fully around the distal portion  201 , in yet another option. Prior to coupling the skirt  600  with the flexible element distal portion  201 , the skirt  600  has an inner surface  602  sized and shaped to fit around the flexible element  200  and allow positioning of the skirt  600  along the element  200 . Optionally, the inner surface  602  has a substantially cylindrical geometry prior to coupling of the skirt  600  to the flexible element  200 . 
     In one option, the skirt  600  is positioned along the flexible element distal portion  201  and deformed (e.g., crimped) to engage against the distal portion  201 . The skirt  600  is thereby substantially immobilized along the flexible element  200 . As shown in  FIG. 6 , the skirt  600  is deformed at a discrete point to create at least one projection, such as spur  604 . In the example shown in  FIG. 6 , the skirt  600  is deformed to include four spurs  604 . The spurs  604  engage the inner surface  602  of the skirt  600  with the flexible element distal portion  201 . Optionally, the flexible element distal portion  201  includes projections and the inner surface  602  of the skirt  600  is crimped over the projections to couple the skirt to the distal portion  201 . 
     In another option, the spurs  604  extend into the flexible element  200  and deform the flexible element  600  to define corresponding recesses sized and shaped to receive the spurs  604 . Optionally, the spurs  604  extend between individual filars of the flexible element  200  (e.g., a wire with a plurality of steel filars). The spurs  604  immobilize the skirt  600  along the flexible element  200  without substantially weakening the flexible element  200 . Additionally, the spurs  604  allow the skirt  600  to have a substantially enlarged uncrimped profile while only a small portion of the skirt  600  is narrowed to form the spurs  600 . When coupled to the flexible element  200  with the spurs  604 , the skirt  600  has a larger profile and improved anchoring within the encapsulant  214 . In another option, the skirt  600  includes additional features, such as knurling, ridges, recesses or the like, as previously described. These additional features provide an even larger profile for the encapsulant  214  to grasp and anchor the skirt  600 , further enhancing transmission of pushing and pulling to the deflectable distal end portion  102 . In another option, where the flexible element distal portion  201  is coupled to a marker band  212  ( FIG. 2 ), the skirt  600  substantially prevents puncturing of the catheter body  110  if the flexible element  200  fractures adjacent to the marker band  212 . 
       FIG. 7  shows yet another example of a skirt  700  coupled along the distal portion  201  of the flexible element  200 . In one option, the flexible element distal portion  201  is free of welds and is not coupled with the marker band  212 . In another option, the flexible element distal portion  201  is coupled to the marker band  212  (See  FIG. 2 ) distally relative to the skirt  700 . The distal portion  201  is optionally welded to the marker band  212 . 
     In one option, the skirt  700  acts as a clamp and is deformable to engage against the flexible element distal portion  201 . As described above, the skirt  700  includes, but is not limited to, metals such as steel, aluminum or the like. In another option, the skirt  700  is overmolded around the flexible element distal portion  201  to couple the skirt  700  to the flexible element  200 . The skirt  700  includes, for instance, but is not limited to metals, polymers or the like. Optionally, the skirt  700  extends part way around the flexible element distal portion  201 . The skirt  700  extends fully around the distal portion  201 , in another option. 
     As shown in  FIG. 7 , the skirt  700  includes projections  702  sized and shaped to fit within recesses  704  formed in the flexible element distal portion  201 . In one option, the ends of the skirt  700  are crimped to form the projections  702 . The projections  702  engage the distal portion  201  and form the recesses  704 . In another option, the recesses  704  are pre-formed in the flexible element distal portion  201  and the projections  702  are positioned within the recesses  704  to engage the skirt  700  to the distal portion  201 . The recesses are formed, optionally, by deformation of the flexible element, etching, drilling or the like. In yet another option, the skirt  700  includes recesses and the flexible element distal portion  201  includes projections sized and shaped to fit within the recesses. 
     When coupled to the flexible element distal portion  201 , the skirt  700  is substantially immobilized along the flexible element  200 . The skirt  700  provides an enlarged profile for the flexible element distal portion  201  and facilitates grasping of the flexible element  200  by the encapsulant  214 . Optionally, the skirt  700  includes additional features, such as knurling, ridges, recess or the like, as described above. Additional features present an even larger profile for the encapsulant  214  to anchor the skirt  700 , further enhancing transmission of pushing and pulling to the deflectable distal end portion  102  through the encapsulant  214 . In another option, where the flexible element distal portion  201  is coupled to a marker band  212  ( FIG. 2 ), the skirt  700  substantially prevents puncturing of the catheter body  110  if the flexible element  200  fractures adjacent to the marker band  212 . 
       FIG. 8A  shows one example of the deflectable distal end portion  102  including a skirt  800 A having a flared portion  802 A (e.g., a paddle geometry).  FIGS. 8B , C, D show additional examples of skirts  800 B, C, D with flared portions  802 B, C, D having different geometries. Each of the flared portions  802 A-D provide a large profile for the encapsulant  214  ( FIG. 8A ) to grasp and immobilize the skirts  800 A-D. The skirts  800 A-D provide improved transmission of pushing and pulling forces to the deflectable distal end portion  102 . In another option, where the flexible element distal portion  201  is coupled to a marker band  212  ( FIG. 2 ), the skirts  800 A-D substantially immobilize the flexible element distal portion  201  to prevent puncturing of the catheter body  110  if the flexible element  200  fractures adjacent to the marker band  212 . Optionally, the flared portions  802 A-D are located distally relative to the flexible element distal portion  201 . In another option, the flared portions  802 A-D are coincident with the flexible element distal portion  201 , for instance the tip of the distal portion is disposed within one of the flared portions  802 A-D. 
     As shown in  FIG. 8A , the skirt  800 A includes a flared portion  802 A and a proximal portion  804 . The flared portion  802 A provides a wide and flat profile extending outside of the profile of the proximal portion  804  to facilitate grasping by the encapsulant  214 . The flared portion  802 A is formed, in one option, by stamping the skirt  800 A in the region distal to the proximal portion  804 . In another option, the flared portion  802 A is formed by molding, machining or the like. The skirt  800 A is optionally stamped with a die that defines the geometry of the flared portion  802 A. Other examples of flared portions are shown in  FIGS. 8B , C, D. The flared portion  802 B ( FIG. 8B ), in one option, is formed with a die that projects the flared portion  802 B away from the proximal portion  804  with a curved geometry. In another option, the curved geometry complements the rounded geometry of the deflectable distal end portion  102 . As shown in  FIG. 8C , in yet another option, the skirt  800 C is stamped with a die that projects the flared portion  802 C further away from the proximal portion  804  than the flared portion  802 B of skirt  800 B. The flared portions  802 B, C remain substantially adjacent to the proximal portion  804  to substantially minimize shearing of the flared portions  802 B, C. Optionally, the skirts  800 A-D are constructed with, but not limited to, deformable materials such as metals that maintain the geometries of the flared portions  802 A-D. In one example, the skirts  800 A-D include stainless steel. 
     In another option shown in  FIG. 8D , the flared portion  802 D is formed with a die that projects the flared portion  802 D away from the proximal portion  804  and also forms at least one recess, such as corrugation  806 . The corrugation  806  defines a non-annular feature for the flared portion  802 D. The profile of the flared portion  802 D including the added feature of the corrugation  806  enhances immobilization of the skirt  800 D within the encapsulant ( FIG. 8A ). The flared portion  802 D having the corrugation  806  transmits pushing and pulling forces to the deflectable distal end portion  102  ( FIG. 8A ). 
     Referring again to  FIG. 8A , the proximal portion  804 , in one option, extends substantially around the flexible element distal portion  201  and is crimped around the distal portion  201  to couple the skirt  800 A with the flexible element  200 . In another option, the proximal portion  804  extends part way around the flexible element distal portion  201  and is crimped to couple the skirt  800 A with the flexible element  200 . In a similar manner, the proximal portions  804  of the skirts  800 B, C, D are crimped to couple the skirts with the flexible element  200 , optionally. In yet another option, the skirts  800 A-D are coupled with the flexible element with other means including, but not limited to, adhesives, molding or the like. 
     A deflectable distal end portion  102  including a skirt  900  integral to the flexible element distal portion  201  is shown in  FIG. 9 . The skirt  900  includes features, such as knurling  902 , provided to anchor the flexible element distal portion  201  within the encapsulant  214 . In one option, the knurling  902  extends around the distal portion  201 . In another option, the knurling  902  extends part way around the distal portion  201 . 
     Optionally, the knurling  902  includes brazing dots formed with metals such as aluminum, copper and the like. The brazing dots are applied to the flexible element distal portion  201  by melting the brazing material and applying it as dots. The brazing dots cool and solidify to form the knurling  902 . In another option, the flexible element  200  is molded, crimped or the like to form the knurling  902 . Crimping the flexible element  200  compresses the element in one dimension while widening the element  200  in another dimension. 
     In a similar manner to the skirts  220 ,  400 A-D,  500 A, B,  600 ,  700  and  800 A-D, the skirt  900  provides an enlarged profile for the flexible element distal portion  201  and facilitates grasping of the flexible element  200  by the encapsulant  214 . The skirt  900  provides improved transmission of pushing and pulling forces to the deflectable distal end portion  102  through the encapsulant  214 . In another option, where the flexible element distal portion  201  is coupled to a marker band  212  ( FIG. 2 ), the skirt  900  substantially prevents puncturing of the catheter body  110  if the flexible element  200  fractures adjacent to the marker band  212 . 
       FIG. 10  illustrates another example of a deflectable distal end portion  102  including a skirt  1000  integral to the flexible element distal portion  201 . The skirt  1000  includes features, such as recesses  1002 , provided to receive the encapsulant  214  and thereby anchor the flexible element distal portion  201  within the encapsulant  214 . In one option, the skirt  1000  further includes flaring  1004  disposed between the recesses  1002  to improve the anchoring of the skirt  1000  within the encapsulant  214 . Optionally, the recesses  1002  and/or flaring  1004  extend part way around the distal portion  201 . The recesses  1002  and/or flaring  1004  extend all the way around the flexible element distal portion  201 , in another option. 
     The recesses  1002  and flaring  1004  are formed, in one option, by crimping and deforming the flexible element distal portion  201 . The recesses  1002  are formed by crimping, molding, etching or the like along the flexible element  200 . The flaring  1004  is formed, in another option, by pulling the flexible element distal portion  201  radially to increase the circumference around the distal portion  201 . Where the flexible element  200  includes multiple filars (e.g., steel filars), radially pulling on the element  200  pulls at least some of the filars outward to form the flaring  1004 . Optionally, the flaring  1004  is formed as the flexible element  200  is longitudinally compressed along a portion of its length corresponding to the skirt  1000 . The compression bows out the filars of the flexible element  200  to form the flaring  1004 . In yet another option, the flaring  1004  and/or recesses  1002  are formed alone without the other of the flaring  1004  or the recesses  1002 . 
     Similar to the examples described above, the skirt  1000  provides an enlarged profile for the flexible element distal portion  201  and facilitates grasping of the flexible element  200  by the encapsulant  214 . The flaring  1004  and the recesses  1002  anchor the flexible element distal portion  201  within the encapsulant  214  to provide improved transmission of pushing and pulling forces to the deflectable distal end portion  102 . In another option, where the flexible element distal portion  201  is coupled to a marker band  212  ( FIG. 2 ), the skirt  1000  substantially prevents longitudinal movement of the flexible element distal portion  201  within the catheter body  110 , for instance, if the flexible element  200  fractures adjacent to the marker band  212 . Puncturing of the catheter body  110  is thereby substantially prevented by anchoring the skirt  1000  within the encapsulant of the deflectable distal end portion  102 . 
       FIG. 11  shows a partial cut-away of another example of a deflectable distal end portion  1100  of the catheter body  110  shown in  FIGS. 1A , B, C. The deflectable distal end portion  1100  is similar in some respects to the deflectable distal end portion  102  shown in  FIG. 2 . The catheter body  110  includes a catheter liner  202  having a catheter lumen  204  extending therein. The distal end of the catheter liner  202  forms at least a portion of the deflectable distal end portion  1100 . A flexible element duct  206  is positioned along the catheter liner  202 , in one option. As shown in  FIG. 11 , the flexible element duct  206  extends from an intermediate portion  207  of the catheter body  110  (e.g., proximal to the deflectable distal end portion  102 ) toward the proximal end  106  adjacent to the handle assembly  150  ( FIGS. 1A , B, C). In another example, the distal end  208  of the flexible element duct  206  is proximal to a distal tip  210  of the catheter body  110 . The flexible element duct  206  includes an actuator lumen sized and shaped to receive the flexible element  200  (e.g., the flexible element duct  206  defines the actuator lumen). In one option, the flexible element  200  is slidably coupled with the flexible element duct  206  to facilitate transmission of pushing and pulling forces for deflection of the deflectable distal end portion  102 . 
     In one option, a distal portion  201  of the flexible element  200  extends from the distal end  208  of the flexible element duct  206  toward the distal tip  210  of the catheter body  110 . In another option, the flexible element distal portion  201  extends from the distal end  208  of the duct  206  toward a marker band  212 . The marker band  212  extends around the catheter liner  202 . Optionally, the marker band  212  is coupled to the catheter liner  202  with crimping, adhesives, overmolding or the like. The marker band  212  is fluoroscopic in still another option, facilitating viewing of the deflectable distal end portion  1100  during procedures (e.g., when the catheter body  110  is within vasculature). 
     As described above, the catheter liner  202 , flexible element duct  206 , flexible element  200 , and the marker band  212  are surrounded by the encapsulant  214 . The encapsulant  214  grasps the components and immobilizes them with respect to the catheter body  110 . The encapsulant  214  forms the sidewall  215  and at least a portion of the outer surface  217  of the catheter body  110  surrounding the catheter lumen  204 . At least the flexible element duct  206  and the flexible element  200  are contained within the encapsulant  214  and outside of the catheter lumen  204 . 
     As shown in  FIG. 11 , the skirt  220  is disposed around the distal portion  201  of the flexible element  200 . The skirt  220  is grasped by the encapsulant  214  to transmit pushing and pulling forces from the flexible element  200  to the deflectable distal end portion  1100  (described above). The skirt  220  is a separate feature from the marker band  212 . The skirt  220 , as shown in  FIG. 11 , is proximal to the marker band  212  and separated from the marker band  212  by a space, such as gap  1102 . Because the flexible element distal portion  201  is not coupled with the marker band  212  the skirt  220  and the distal portion  201  are spaced a predetermined distance from the marker band  212 . The gap  1102 , in one option, thereby contains features sandwiched between the skirt  220  and the marker band  212 . The features include, but are not limited to, instruments (e.g., for measuring temperature, pressure and the like), electrodes, openings, such as flush openings  1104  and the like. The flush openings  1104  are adapted to discharge fluid, including, but not limited to, saline, contrast media and the like. The flush openings  1104  help to prevent blood clots that form around the catheter body  110 , clear out air before procedures and inject contrast media (e.g., for fluoroscopy). Because the gap  1102  is variable, combinations of features are located in the gap  1102 , in another option. 
     Referring to  FIGS. 1A , B, C, in operation, the actuator of the handle assembly  150  (e.g., the wheel  104 , slide, knob, pull ring and the like) is moved to deflect the deflectable distal end portion  102  from a neutral position ( FIG. 1B ) to disparate deflected orientations, such as the orientations shown in  FIGS. 1A , C. Referring now to  FIG. 2 , the flexible element  200  is pushed and/or pulled by the actuating mechanisms in the handle assembly  150  to deflect the distal end portion  102 . The pushing and pulling forces are transmitted along the flexible element  200  to the flexible element distal portion  201 . The distal portion  201 , in one option, is coupled to the deflectable distal end portion  102  at the marker band  212  and by encapsulating the skirt  220  within the encapsulant  214 . The pushing and pulling forces are transmitted to the catheter liner  202  and the encapsulant  214  by the skirt  220  and the marker band  212 . The pushing and pulling forces transmitted by the marker band  212  and the skirt  220  deflect the deflectable distal end portion  102  into a desired orientation (e.g., the orientations shown in  FIGS. 1A , C). Optionally, skirts  400 A-D,  500 A, B,  600 ,  700  and  800 A-D,  900  and  1000  are used in a similar manner during operation of the catheter assembly  100 . In another option, multiple skirts are used along the flexible element distal portion  201 . 
     The skirt  220  operates to distribute the pushing and pulling stresses away from the marker band  212  and thereby substantially reduce fracturing of the flexible element distal portion  201  adjacent to the marker band  212 , for instance at an annealed region near a weld. Additionally, the skirt  220  and the flexible element  200  have tension and compression strengths equal to or greater than the corresponding tension and compression strengths of the encapsulant  214 . Fracture of the flexible element  200  is thereby substantially reduced and the catheter body  110  ( FIGS. 1A-C  and  2 ) is adapted to fail before failure of the element  200  and the skirt  220 , thereby substantially preventing puncturing of the catheter body  110  with a fractured element. 
     Optionally, where the flexible element distal portion  201  fractures adjacent to the marker band  212  the skirt  220  substantially immobilizes the distal portion  201  and prevents it from puncturing the catheter body  110 . In still another option, a skirt including several features (e.g., knurling, corrugations, flaring or the like) is coupled with the flexible element distal portion  201  to enhance distribution of pushing and pulling forces and further reduce fracturing of the distal portion  201 . Additionally, the skirt with multiple features enhances immobilization of a fractured flexible element  200  to further prevent puncturing of the catheter body  110 . 
     Referring now to  FIG. 3 , in another option, the skirt  220  is used with a flexible element distal portion  201  that is not coupled with the marker band  212 . The pushing and pulling forces provided by the flexible element  200  are transmitted to the deflectable distal end portion  102  through the skirt  220  anchored within the encapsulant  214 . The pushing and pulling forces transmitted through the skirt  220  operate to deflect the distal end portion  102  into desired orientations, for example, the orientations shown in  FIGS. 1A , C. Because the skirt is coupled to the flexible element  200  without welding the element  200  experiences no stresses at an annealed region and the risk of fracturing the flexible element  200  is substantially reduced. As described above, the skirt  220  and the flexible element  200  have tension and compression strengths at least as great as the tension and compression strengths of the encapsulant  214  and thereby substantially reduce fracture of the flexible element  200 . Optionally, the catheter body  110  ( FIGS. 1A-C  and  2 ) is adapted to fail before failure of the flexible element  200  and the skirt  220 , and thereby substantially prevent the puncturing of the catheter body  110  by a fractured element. 
     Optionally, skirts  400 A-D,  500 A, B,  600 ,  700 ,  800 A-D,  900  and  1000  are used in a similar manner to skirt  220  during operation of the catheter assembly  100 . In another option, multiple skirts are used along the flexible element distal portion  201 . In still another option, a skirt including several features (e.g., knurling, corrugations, flaring or the like) is coupled with the flexible element distal portion  201  to enhance anchoring of the distal portion  201  within the encapsulant  214 . 
       FIG. 12  is a block diagram illustrating one example of a method  1200  for making a catheter body. At  1202  a flexible element is positioned along a catheter liner. A distal portion of the flexible element extends along at least a portion of a deflectable distal end portion of the catheter liner. At  1204  at least one skirt is coupled to the flexible element distal portion, and the at least one skirt extends at least part way around the flexible element distal portion. In one option, the flexible element distal portion proximal to the at least one skirt is free of annealing (e.g., annealing caused by welds). At  1206  an encapsulant (e.g., PEBAX) is positioned around at least the flexible element distal portion and the deflectable distal end portion. At  1208 , the encapsulant is squeezed around the flexible element distal portion and the skirt. The encapsulant forms at least a portion of a sidewall of the deflectable distal end portion and at least the skirt is within the sidewall. The encapsulant is adapted to transmit pushing and pulling forces from the at least one skirt to the deflectable distal end portion. Additionally, the tension strength and compression strength of the flexible element and the at least one skirt are at least as strong as the encapsulant tension strength and compression strength. In another option, the encapsulant is adapted to fail before the flexible element and the at least one skirt. 
     Several options for the method  1200  follow. In one option, the method  1200  includes substantially preventing a puncture of the encapsulant by the flexible element, for instance, by anchoring the skirt within the encapsulant. In another option, a marker band is included in the deflectable distal end portion. The skirt and the flexible element distal portion are positioned proximal to the marker band. The flexible element distal portion and the skirt are spaced proximally from the marker band, optionally, because the flexible element is not coupled to the marker band. Features, such as flushing ports, are formed in the space between the skirt and the marker band, in yet another option. The marker band is coupled to the flexible element distal portion with a weld substantially adjacent to the deflectable distal end portion, in yet another option. Pushing and pulling forces a distributed between the skirt and the marker band to minimizes the forces experienced at the weld. The method  1200  includes, optionally, substantially preventing fracture of the flexible element adjacent to the marker band (e.g., at an annealed or weakened region). 
     In one option, the method  1200  includes flaring (e.g., by stamping) at least one of the flexible element distal portion and the at least one skirt. In another option, the skirt includes a clamp, and the method  1200  includes deforming the skirt and the skirt grasps the flexible element distal portion. Deforming the skirt includes, optionally, crimping the clamp at a plurality of points along the clamp. In yet another option, the method  1200  includes engaging a projection extending from at least one of the skirt and the flexible element distal portion against the other of the skirt and the distal portion. Engaging the projection includes seating the projection within at least one recess sized and shaped to receive the projection, in still yet another option. The recess is formed in at least one of the skirt and the flexible element distal portion. In a further option, engaging the projection includes using the projection to deform at least one of the flexible element and the skirt. For instance, the projection grasps the flexible element by deforming at least a portion of flexible element. Optionally, the method  1200  includes forming at least one recess (e.g., holes, corrugations, or the like) in the skirt. The at least one recess, in another option, receives the encapsulant and thereby securely anchors the skirt and the flexible element distal portion in the encapsulant. The skirt and the flexible element distal portion are integral and the recesses are formed in the flexible element distal portion, in yet another option. 
     The above described catheter allows for deflection of a deflectable distal end portion while substantially preventing fracture of a flexible element. Pushing and pulling forces from the flexible element are transmitted through the skirt to the encapsulant and the catheter liner at the deflectable distal end portion of the catheter. The skirt anchored in the encapsulant facilitates deflection of the deflectable distal end portion through transmission of the pushing and pulling forces. In one option, the skirt is integral to the flexible element distal portion. Where the flexible element distal portion is not coupled to a marker band optionally, the skirt and the flexible element are disposed along the catheter body proximal to a marker band used to see the tip of the catheter body during procedures (e.g., with fluoroscopy). Proximally positioning the skirt provides additional space to include features, for instance flush openings and the like, positioned between the skirt and marker band. 
     The flexible element and the skirt have tension and compression strengths at least as great as the tension and compression strengths of the encapsulant to substantially reduce fracture of the flexible element. Optionally, the catheter body is adapted to fail before failure of the flexible element and the skirt, and puncturing of the catheter body is thereby substantially prevented by a fractured element. In another option, the skirt is coupled to the flexible element distal portion without a weld. Fracturing of the flexible element is thereby substantially reduced because stress is not applied to a weakened annealed region. Additionally, the skirt is localized around the flexible element without extending remotely around the deflectable distal end portion. The skirt thus provides improved strength and durability against failure through shearing. Moreover, because the skirt is localized substantially adjacent to the flexible element pushing and pulling forces are not distributed around the catheter body. The deflectable distal end portion thus experiences an improved deflection response with the concentrated pushing and pulling of the flexible element. 
     In another option, the skirt cooperates with the marker band coupled to the flexible element distal portion. The marker band is coupled to the flexible element distally relative to the skirt. The skirt acts as a supplementary anchor and distributes pushing and pulling forces between the marker band and itself. Fracturing of the flexible element adjacent to the marker band (e.g., the annealed region near a weld) is substantially reduced because the pushing and pulling forces are distributed between the skirt and the marker band. Additionally, where the flexible element distal portion does fracture adjacent the marker band, the skirt embedded in the encapsulant acts to substantially immobilize the fractured flexible element and substantially prevent puncturing of the catheter body. Moreover, the skirt facilitates continued use of the catheter with a fractured flexible element because the skirt continues to function as an anchor and transmits pushing and pulling forces to the deflectable distal end portion. 
     Additionally, the encapsulant is squeezed around the catheter liner to easily form an outer surface and sidewall of the catheter body and grasp the skirt. In one option, the skirt is in the sidewall and thereby provides a larger moment to the deflectable distal end portion because it is positioned remotely from the center of the catheter body. As described above, the encapsulant flows around the skirt and, when hardened, transmits tension and compression forces to the deflectable distal end portion while also acting as the outer surface of the catheter body. Complex manufacturing procedures including drilling and/or forming a pocket for an anchor and injecting an adhesive over the anchor are thereby avoided. Further, the skirt is retained along the catheter body and the distal end therefore does not house the skirt and/or the flexible element in a hard tip. In one option, the distal end of the catheter body thereby has a soft atraumatic tip. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reading and understanding the above description. It should be noted that embodiments discussed in different portions of the description or referred to in different drawings can be combined to form additional embodiments of the present application. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.