Patent Publication Number: US-2022218944-A1

Title: Flexible and stretch resistant elongate shaft

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of and priority to U.S. Prov. Patent App. No. 63/137,293, filed Jan. 14, 2021, titled FLEXIBLE AND STRETCH RESISTANT ELONGATE SHAFT, the disclosure of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure pertains to medical devices and methods for manufacturing and/or using medical devices. More particularly, the present disclosure pertains to configurations of a flexible and stretch resistant elongate shaft and methods of making a flexible and stretch resistant elongate shaft. 
     BACKGROUND 
     A wide variety of intracorporeal medical devices have been developed for medical use, for example, surgical and/or intravascular use. Some of these devices include guidewires, catheters, medical device delivery systems (e.g., for stents, grafts, replacement valves, etc.), 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. There is an ongoing need to provide alternative medical devices as well as alternative methods for manufacturing and/or using medical devices. 
     SUMMARY 
     In a first example, a method of manufacturing an elongate shaft for delivery of a medical device may comprise: disposing a polymeric sheath having a lumen extending therethrough over a mandrel; sliding a proximal portion of the polymeric sheath into a lumen of a metallic tubular member; placing a polymeric tubular member over the distal portion of the polymeric sheath and a distal portion of the metallic tubular member; fixedly attaching a proximal coupler to a distal end of a longitudinal support filament; inserting a proximal end of the longitudinal support filament between the polymeric sheath and the polymeric tubular member to position the longitudinal support filament alongside the distal portion of the metallic tubular member and a distal portion of the polymeric sheath; and reflowing the polymeric tubular member to secure the longitudinal support filament relative to the polymeric sheath and the metallic tubular member. 
     In addition or alternatively to any example disclosed herein, a distal portion of the longitudinal support filament is positioned against an outer surface of the distal portion of the polymeric sheath. In addition or alternatively to any example disclosed herein, proximal portion of the longitudinal support filament is positioned against an outer surface of the distal portion of the metallic tubular member. In addition or alternatively to any example disclosed herein, the method may comprise: before reflowing the polymeric tubular member, engaging the proximal coupler with a distal end of the polymeric sheath. In addition or alternatively to any example disclosed herein, the medical device includes a distal coupler configured to axially overlap and releasably engage the proximal coupler. 
     In addition or alternatively to any example disclosed herein, the method may comprise: after reflowing the polymeric tubular member, removing the mandrel from the lumen of the polymeric sheath; and thereafter disposing a release wire axially within the lumen of the polymeric sheath, and through the proximal coupler and the distal coupler to releasably couple the medical device to the proximal coupler. In addition or alternatively to any example disclosed herein, the polymeric tubular member includes a proximal portion formed from a first polymeric material and a distal portion formed from a second polymeric material different from the first polymeric material. In addition or alternatively to any example disclosed herein, the method may comprise: after reflowing the polymeric tubular member, applying a hydrophobic coating to an outer surface of the polymeric tubular member. In addition or alternatively to any example disclosed herein, the longitudinal support filament is a metallic wire. 
     In addition or alternatively to any example disclosed herein, the metallic tubular member includes a proximal portion and a distally tapered portion extending from the proximal portion to the distal portion. In addition or alternatively to any example disclosed herein, after reflowing the polymeric tubular member, a proximal-most end of the polymeric tubular member is disposed distal of the distally tapered portion of the metallic tubular member. In addition or alternatively to any example disclosed herein, the method may comprise: before reflowing the polymeric tubular member, positioning a tubular heat shrink member over the polymeric tubular member. In addition or alternatively to any example disclosed herein, an outer surface of the polymeric sheath is etched. 
     In addition or alternatively to any example disclosed herein, and in a second example, a method of manufacturing an elongate shaft for delivery of a medical device may comprise: extruding a polymeric tubular member and a longitudinal support filament over a first polymeric sheath disposed on a mandrel to form a composite tubular member; sliding a metallic tubular member over a second polymeric sheath and securing a distal end of the second polymeric sheath to a distal end of the metallic tubular member; placing the composite tubular member, with the mandrel removed, over a distal portion of the metallic tubular member; and reflowing a proximal portion of the polymeric tubular member onto the distal portion of the metallic tubular member to secure the longitudinal support filament relative to the metallic tubular member. 
     In addition or alternatively to any example disclosed herein, a proximal portion of the first polymeric sheath is removed from within the composite tubular member before placing the composite tubular member over the distal portion of the metallic tubular member. In addition or alternatively to any example disclosed herein, reflowing the proximal portion of the polymeric tubular member secures the longitudinal support filament against an outer surface of the distal portion of the metallic tubular member. In addition or alternatively to any example disclosed herein, the method may comprise: fixedly attaching a proximal coupler to a distal end of the longitudinal support filament. In addition or alternatively to any example disclosed herein, a distal portion of the polymeric tubular member is removed to expose the distal end of the longitudinal support filament prior to fixedly attaching the proximal coupler. 
     In addition or alternatively to any example disclosed herein, an elongate shaft for delivery of a medical device may comprise a polymeric sheath having a lumen extending therethrough; a metallic tubular member disposed over a proximal portion of the polymeric sheath; a polymeric tubular member disposed over a distal portion of the polymeric sheath and a distal portion of the metallic tubular member; a longitudinal support filament extending along the distal portion of the polymeric sheath and the distal portion of the metallic tubular member; and a proximal coupler fixedly attached to a distal end of the longitudinal support filament. The polymeric tubular member may secure the longitudinal support filament relative to the polymeric sheath and the metallic tubular member. The polymeric tubular member may include a proximal portion, a distal portion, and a middle portion having a lower bending stiffness than the proximal portion and the distal portion. The longitudinal support filament may extend within the proximal portion, the middle portion, and the distal portion of the polymeric tubular member. The longitudinal support filament may substantially prevent axial stretching of the polymeric tubular member. 
     In addition or alternatively to any example disclosed herein, the middle portion defines a preferential bending location of the elongate shaft. 
     The above summary of some embodiments, aspects, and/or examples is not intended to describe each embodiment or every implementation of the present disclosure. The figures and the detailed description which follows more particularly exemplify these embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying drawings, in which: 
         FIG. 1  illustrates aspects of a medical device system including a delivery shaft; 
         FIGS. 2-12  illustrate aspects of a reflow method of manufacturing a delivery shaft; 
         FIGS. 13-17  illustrate aspects of a method of manufacturing a delivery shaft; 
         FIGS. 18-19  illustrate aspects of an alternative configuration for a delivery shaft; 
         FIG. 20  is a cross-section of the delivery shaft; and 
         FIG. 21  is a cross-section of an alternative configuration of the delivery shaft. 
     
    
    
     While aspects of the disclosure are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit aspects of the disclosure to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure. 
     DETAILED DESCRIPTION 
     The following description should be read with reference to the drawings, which are not necessarily to scale, wherein like reference numerals indicate like elements throughout the several views. The detailed description and drawings are intended to illustrate but not limit the present disclosure. Those skilled in the art will recognize that the various elements described and/or shown may be arranged in various combinations and configurations without departing from the scope of the disclosure. The detailed description and drawings illustrate example embodiments of the disclosure. However, in the interest of clarity and ease of understanding, while every feature and/or element may not be shown in each drawing, the feature(s) and/or element(s) may be understood to be present regardless, unless otherwise specified. 
     For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification. 
     All numeric values are herein assumed to be modified by the term “about,” whether or not explicitly indicated. The term “about”, in the context of numeric values, generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (e.g., having the same function or result). In many instances, the term “about” may include numbers that are rounded to the nearest significant figure. Other uses of the term “about” (e.g., in a context other than numeric values) may be assumed to have their ordinary and customary definition(s), as understood from and consistent with the context of the specification, unless otherwise specified. The recitation of numerical ranges by endpoints includes all numbers within that range, including the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). Although some suitable dimensions, ranges, and/or values pertaining to various components, features and/or specifications are disclosed, one of skill in the art, incited by the present disclosure, would understand desired dimensions, ranges, and/or values may deviate from those expressly disclosed. 
     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. It is to be noted that in order to facilitate understanding, certain features of the disclosure may be described in the singular, even though those features may be plural or recurring within the disclosed embodiment(s). Each instance of the features may include and/or be encompassed by the singular disclosure(s), unless expressly stated to the contrary. For simplicity and clarity purposes, not all elements of the present disclosure are necessarily shown in each figure or discussed in detail below. However, it will be understood that the following discussion may apply equally to any and/or all of the components for which there are more than one, unless explicitly stated to the contrary. Additionally, not all instances of some elements or features may be shown in each figure for clarity. 
     Relative terms such as “proximal”, “distal”, “advance”, “retract”, variants thereof, and the like, may be generally considered with respect to the positioning, direction, and/or operation of various elements relative to a user/operator/manipulator of the device, wherein “proximal” and “retract” indicate or refer to closer to or toward the user and “distal” and “advance” indicate or refer to farther from or away from the user. In some instances, the terms “proximal” and “distal” may be arbitrarily assigned in an effort to facilitate understanding of the disclosure, and such instances will be readily apparent to the skilled artisan. Other relative terms, such as “upstream”, “downstream”, “inflow”, and “outflow” refer to a direction of fluid flow within a lumen, such as a body lumen, a blood vessel, or within a device. Still other relative terms, such as “axial”, “circumferential”, “longitudinal”, “lateral”, “radial”, etc. and/or variants thereof generally refer to direction and/or orientation relative to a central longitudinal axis of the disclosed structure or device. 
     The term “extent” may be understood to mean a greatest measurement of a stated or identified dimension, unless the extent or dimension in question is preceded by or identified as a “minimum”, which may be understood to mean a smallest measurement of the stated or identified dimension. For example, “outer extent” may be understood to mean an outer dimension, “radial extent” may be understood to mean a radial dimension, “longitudinal extent” may be understood to mean a longitudinal dimension, etc. Each instance of an “extent” may be different (e.g., axial, longitudinal, lateral, radial, circumferential, etc.) and will be apparent to the skilled person from the context of the individual usage. Generally, an “extent” may be considered a greatest possible dimension measured according to the intended usage, while a “minimum extent” may be considered a smallest possible dimension measured according to the intended usage. In some instances, an “extent” may generally be measured orthogonally within a plane and/or cross-section, but may be, as will be apparent from the particular context, measured differently—such as, but not limited to, angularly, radially, circumferentially (e.g., along an arc), etc. 
     The terms “monolithic” and “unitary” shall generally refer to an element or elements made from or consisting of a single structure or base unit/element. A monolithic and/or unitary element shall exclude structure and/or features made by assembling or otherwise joining multiple discrete structures or elements together. 
     It is noted that references in the specification to “an embodiment”, “some embodiments”, “other embodiments”, etc., indicate that the embodiment(s) 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 are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it would be within the knowledge of one skilled in the art to affect the particular feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described, unless clearly stated to the contrary. That is, the various individual elements described below, even if not explicitly shown in a particular combination, are nevertheless contemplated as being combinable or arrangeable with each other to form other additional embodiments or to complement and/or enrich the described embodiment(s), as would be understood by one of ordinary skill in the art. For the purpose of clarity, certain identifying numerical nomenclature (e.g., first, second, third, fourth, etc.) may be used throughout the description and/or claims to name and/or differentiate between various described and/or claimed features. It is to be understood that the numerical nomenclature is not intended to be limiting and is exemplary only. In some embodiments, alterations of and deviations from previously used numerical nomenclature may be made in the interest of brevity and clarity. That is, a feature identified as a “first” element may later be referred to as a “second” element, a “third” element, etc. or may be omitted entirely, and/or a different feature may be referred to as the “first” element. The meaning and/or designation in each instance will be apparent to the skilled practitioner. 
       FIG. 1  illustrates aspects of a medical device system. The medical device system may include an elongate shaft  110  having a lumen extending from a proximal portion of the elongate shaft  110  to a distal end of the elongate shaft  110 . In some embodiments, the elongate shaft  110  may be a tubular and/or annular structure defined by a wall having an inner surface and an outer surface. In some embodiments, the lumen may extend along and/or may be coaxial with a central longitudinal axis of the elongate shaft  110 . In some embodiments, the elongate shaft  110  may have a substantially constant and/or uniform outer extent and/or outer diameter along at least a portion of its length. Other configurations, including but not limited to the elongate shaft  110  having one or more tapers, steps, and/or changes in outer extent and/or outer diameter, are also contemplated. In some embodiments, the elongate shaft  110  may have an overall length of about 120 centimeters (cm), about 150 cm, about 170 cm, about 180 cm, about 190 cm, about 200 cm, about 210 cm, about 230 cm, or another suitable overall length depending upon the intended procedure. Some suitable materials for the elongate shaft  110 , for example metallic materials, polymer materials, composite materials, etc., are described below. 
     A medical device  180  may be disposed proximate, adjacent, and/or at the distal end of the elongate shaft  110 . The medical device  180  may be releasably attached to the distal end of the elongate shaft  110 . In some embodiments, the medical device  180  may be disposed distal of the distal end of the elongate shaft  110 . For simplicity, the medical device  180  is illustrated herein as a shape memory embolic coil, such as those used to treat aneurysms for example, but other suitable medical devices transported, delivered, used, released, etc. in a similar manner are also contemplated, including but not limited to stents, embolic filters, replacement heart valves, occlusion devices, and/or other medical implants, etc. Some suitable but non-limiting materials for the medical device  180 , for example metallic materials, polymeric materials, composite materials, etc., are described below. 
     In some embodiments, the medical device system may include a microcatheter  190  including a lumen therein sized and configured to deliver the medical device  180  to a treatment site. In at least some embodiments, a distal end of the elongate shaft  110  may be configured to be disposed within a proximal end of the lumen of the microcatheter  190  to facilitate advancement of the elongate shaft  110  and/or the medical device  180  within the lumen of the microcatheter  190 . The elongate shaft  110  and the medical device  180  may be configured to be slidably disposed within the lumen of the microcatheter  190 . In some embodiments, the elongate shaft  110  and the medical device  180  may be advanced through the lumen of the microcatheter  190  for deployment of the medical device  180  at the treatment site. In some embodiments, the microcatheter  190  may facilitate percutaneous delivery of the medical device  180  to the treatment site. In  FIG. 1 , the medical device  180  is shown in a delivery configuration, wherein the medical device  180  is substantially aligned with, coaxial with, and/or colinear with the elongate shaft  110  and/or the central longitudinal axis of the elongate shaft  110 . In at least some embodiments, the medical device  180  may be positioned and/or arranged in a substantially elongated configuration in the delivery configuration. Other configurations are also contemplated. 
     In some embodiments, the medical device  180  may be configured to assume and/or shift to a deployed configuration when unconstrained (e.g., in situ, etc.). In some embodiments, the medical device  180  may be heat set in the deployed configuration using a shape memory material such that upon delivery to the treatment site, the patient&#39;s body heat and/or temperature causes the medical device  180  to shift to the deployed configuration when unconstrained (by the microcatheter  190 , for example) and/or when released from the elongate shaft  110 . Some suitable but non-limiting materials for the microcatheter  190 , for example metallic materials, polymeric materials, composite materials, etc., are described below. In some embodiments, the medical device  180  may be shifted into the deployed configuration manually, such as by the use of selective electrical, chemical, and/or magnetic stimulation, a pull wire, etc. In some embodiments, the medical device  180  may be shifted into the deployed configuration automatically, such as by the use of shape memory materials or other suitable methods. The medical device  180  may be shifted into the deployed configuration at any suitable and/or desired time after the medical device  180  has been advanced beyond the distal end of the microcatheter  190 . 
     In some embodiments, a release mechanism  170  may be configured to releasably attach the medical device  180  to the distal end of the elongate shaft  110 . In some embodiments, the elongate shaft  110  may include a proximal coupler  172  of the release mechanism  170  fixedly attached to the distal end of the elongate shaft  110  and the medical device  180  may include a distal coupler  174  of the release mechanism  170  fixedly attached to a proximal end of the medical device  180 . A distal end of a release wire  186  (e.g.,  FIG. 12 ) may slidably engage with the proximal coupler  172  of the release mechanism  170  and the distal coupler  174  of the release mechanism  170 . The release wire  186  may interlock the proximal coupler  172  of the release mechanism  170  with the distal coupler  174  of the release mechanism  170  when the first portion  130  of the metallic tubular member  120  is engaged with the second portion  140  of the metallic tubular member  120  and/or when the release wire  186  is in the first position, as described herein. For example, when the first portion  130  of the metallic tubular member  120  is disengaged and/or separated from the second portion  140  of the metallic tubular member  120 , the release wire  186  may be translated in a proximal direction relative to the elongate shaft  110  to release the distal coupler  174  of the release mechanism  170  and/or the medical device  180  from the proximal coupler  172  of the release mechanism  170  and/or the elongate shaft  110 . In at least some embodiments, the release wire  186  may be slidably disposed within the elongate shaft  110 , the proximal coupler  172  of the release mechanism  170 , and the distal coupler  174  of the release mechanism  170 . Some suitable but non-limiting materials for the release mechanism  170 , the proximal coupler  172 , and/or the distal coupler  174 , for example metallic materials, polymer materials, composite materials, etc., are described below. 
     In some embodiments, the elongate shaft  110  may include several component parts that combine to form the elongate shaft  110 . In some embodiments, the elongate shaft  110  may include a polymeric sheath  150 , a metallic tubular member  120 , and a polymeric tubular member  160 . In some embodiments, the elongate shaft  110  may include additional and/or other component parts and/or elements, as discussed herein. Construction of the elongate shaft  110  is discussed herein and relative positioning and features of each element of the elongate shaft  110  will be apparent. Some of the features discussed herein are shown in  FIG. 1  for reference but are discussed in more detail with respect to subsequent figures. Some suitable but non-limiting materials for the polymeric sheath  150 , the metallic tubular member  120 , and/or the polymeric tubular member  160  are described below. 
       FIGS. 2-12  relate to a method of manufacturing the elongate shaft  110  for delivery of the medical device  180 . As seen in  FIG. 2 , the method may include disposing the polymeric sheath  150  having a lumen extending therethrough on and/or over a mandrel  10 . In some embodiments, the polymeric sheath  150  may be slidably disposed over the mandrel  10 . In some embodiments, the polymeric sheath  150  may be formed directly on the mandrel  10 . For example, the polymeric sheath  150  may be extruded onto the mandrel  10 . In another example, the polymeric sheath  150  may be formed as a tubular structure and the mandrel  10  may be inserted into the polymeric sheath  150  (or the polymeric sheath  150  may be slid over the mandrel  10 ). In one example, the polymeric sheath  150  may have an outer diameter of about 0.006 inches (about 0.1524 millimeters). In other examples, the polymeric sheath  150  may have an outer diameter of about 0.004 inches (0.1016 millimeters) to about 0.008 inches (about 0.2032 millimeters). The mandrel  10  may be removable from the polymeric sheath  150 , as discussed herein. In some embodiments, the mandrel  10  may be slidable with respect to the polymeric sheath  150 . In some embodiments, the polymeric sheath  150  may have a slight friction fit and/or a slight interference fit with the mandrel  10  (e.g., the mandrel  10  may not move freely relative to the polymeric sheath  150 ) that may be overcome at a later time to remove the mandrel  10  from the lumen of the polymeric sheath  150 . In one example, the polymeric sheath  150  may be formed from polytetrafluoroethylene (PTFE). Other materials are also contemplated. In at least some embodiments, an outer surface of the polymeric sheath  150  may be etched and/or otherwise mechanically or chemically treated to facilitate bonding and/or securement to another polymeric material. 
     The method may include sliding a proximal portion of the polymeric sheath  150  into a lumen of the metallic tubular member  120 , wherein the proximal portion of the polymeric sheath  150  is disposed within the metallic tubular member  120  and a distal portion of the polymeric sheath  150  is disposed distal of the metallic tubular member  120 . In some embodiments, the method may include sliding the proximal portion of the polymeric sheath  150  into a distal end of the lumen of the metallic tubular member  120  and advancing the proximal portion of the polymeric sheath  150  at least partially through the metallic tubular member  120 . In one example, the lumen of the metallic tubular member  120  may have an inner diameter of about 0.008 inches (about 0.2032 millimeters). In other examples, the lumen of the metallic tubular member  120  may have an inner diameter of about 0.006 inches (about 0.1524 millimeters) to about 0.010 inches (about 0.254 millimeters). In at least some embodiments, the lumen of the metallic tubular member  120  may have a substantially constant inner diameter along its entire length. 
     The metallic tubular member  120  may include a first portion  130  and a second portion  140 . The first portion  130  of the metallic tubular member  120  may be disposed proximal of a pre-defined break region  122  (e.g.,  FIGS. 1, 12 ) formed in the metallic tubular member  120 . The second portion  140  of the metallic tubular member  120  may be disposed distal of the pre-defined break region  122  formed in the metallic tubular member  120 . In at least some embodiments, the second portion  140  of the metallic tubular member  120  may include a proximal portion  142 , a tapered portion  144 , and a distal portion  146 . The proximal portion  142  of the second portion  140  of the metallic tubular member  120  may have a first outer diameter, the distal portion  146  of the second portion  140  of the metallic tubular member  120  may have a second outer diameter that is less than the first outer diameter, and the tapered portion  144  may taper gradually and/or continuously in a distal direction from the proximal portion  142  and/or the first outer diameter to the distal portion  146  and/or the second outer diameter. In some embodiments, the tapered portion  144  may be referred to as a distally tapered portion, and thus the metallic tubular member  120  may include the proximal portion  142 , the distal portion  146 , and the distally tapered portion (ref.  144 ) extending from the proximal portion  142  to the distal portion  146 . In one example, the metallic tubular member  120  may be formed from nickel-titanium alloy (e.g., nitinol). Other materials are also contemplated. 
     In some embodiments, the metallic tubular member  120  may have an overall length of about 97 centimeters (cm), about 127 cm, about 140 cm, about 155 cm, about 167 cm, about 175 cm, about 190 cm, about 207 cm, or another suitable overall length depending upon the intended procedure. In one example, the distal portion  146  of the second portion  140  of the metallic tubular member  120  may have a length of about 5 cm. In other examples, the distal portion  146  of the second portion  140  of the metallic tubular member  120  may have a length of about 3.5 cm to about 6.5 cm. In one example, the tapered portion  144  of the second portion  140  of the metallic tubular member  120  may have a length of about 15 cm. In other examples, the tapered portion  144  of the second portion  140  of the metallic tubular member  120  may have a length of about 12 cm to about 18 cm. 
     In one example, the first portion  130  of the metallic tubular member  120  may have an outer diameter of about 0.018 inches (about 0.4572 millimeters). In other examples, the first portion  130  of the metallic tubular member  120  may have an outer diameter of about 0.015 inches (about 0.381 millimeters) to about 0.021 inches (about 0.5334 millimeters). In one example, the proximal portion  142  of the second portion  140  of the metallic tubular member  120  may have an outer diameter of about 0.018 inches (about 0.4572 millimeters). In other examples, the proximal portion  142  of the second portion  140  of the metallic tubular member  120  may have an outer diameter of about 0.015 inches (about 0.381 millimeters) to about 0.021 inches (about 0.5334 millimeters). In one example, the distal portion  146  of the second portion  140  of the metallic tubular member  120  may have an outer diameter of about 0.0105 inches (about 0.2667 millimeters). In other examples, the distal portion  146  of the second portion  140  of the metallic tubular member  120  may have an outer diameter of about 0.008 inches (about 0.2032 millimeters) to about 0.012 inches (about 0.3048 millimeters). 
     As seen in  FIGS. 3 and 4 , the method may include placing a polymeric tubular member  160  over the distal portion of the polymeric sheath  150  and the distal portion  146  of the second portion  140  of the metallic tubular member  120 . In some embodiments, a flaring mandrel (not shown) may be inserted into a proximal end of the polymeric tubular member  160  to widen the proximal end of the polymeric tubular member  160  prior to placing the proximal end of the polymeric tubular member  160  over the distal portion  146  of the second portion  140  of the metallic tubular member  120 . The proximal end of the polymeric tubular member  160  may be disposed distal of the tapered portion  144  of the second portion  140  of the metallic tubular member  120 . In some embodiments, heat may be applied to the proximal end of the polymeric tubular member  160  before and/or during insertion of the flaring mandrel to widen the proximal end of the polymeric tubular member  160 . In some embodiments, the flaring mandrel may be heated. In some embodiments, the polymeric tubular member  160  may be advanced proximally over the distal portion of the polymeric sheath  150  and the distal portion  146  of the second portion  140  of the metallic tubular member  120 . 
     In some embodiments, the polymeric tubular member  160  may include a proximal portion  162  (e.g.,  FIG. 8 ) comprising a first polymeric material and a distal portion  164  (e.g.,  FIG. 8 ) comprising a second polymeric material. In at least some embodiments, the first polymeric material may be different from the second polymeric material. In some embodiments, the proximal portion  162  and the distal portion  164  may be bonded, melted, comingled, co-extruded, reflowed, or otherwise permanently joined together to render the polymeric tubular member  160  as a single unitary and/or monolithic structure. In some embodiments, the first polymeric material may be a polyamide 12, such as VESTAMID® L, and the second polymeric material may be a polyether block amide, such as PEBAX®. In one example, the first polymeric material may be VESTAMID® L2101F and the second polymeric material may be PEBAX® 63D. Other materials and/or combinations of materials are also contemplated. In at least some embodiments, the second polymeric material may be softer and/or more flexible than the first polymeric material. 
     In some embodiments, the polymeric tubular member  160  may have an overall length of about 15 centimeters (cm), about 20 cm, about 24 cm, about 26 cm, about 26.5 cm, about 27 cm, about 30 cm, about 35 cm, or another suitable overall length depending upon the intended procedure. In one example, the proximal portion  162  may have a length of about 22 cm and the distal portion  164  may have a length of about 4.5 cm. In other examples, the proximal portion  162  may have a length of about 10 cm to about 30 cm and the distal portion  164  may have a length of about 3 cm to about 6 cm. In some embodiments, the polymeric tubular member  160  may have a substantially uniform outer diameter and/or a substantially uniform inner diameter throughout its entire length, including the proximal portion  162  and the distal portion  164 . However, other configurations, including but not limited to tapered and/or stepped configurations, are also contemplated. In one example, the polymeric tubular member  160  may have an outer diameter of about 0.021 inches (about 0.5334 millimeters). In other examples, the polymeric tubular member  160  may have an outer diameter of about 0.018 inches (about 0.4572 millimeters) to about 0.024 inches (about 0.6096 millimeters). In one example, the polymeric tubular member  160  may have an inner diameter of about 0.015 inches (about 0.381 millimeters). In other examples, the polymeric tubular member  160  may have an outer diameter of about 0.012 inches (about 0.3048 millimeters) to about 0.018 inches (about 0.4572 millimeters). 
     In at least some embodiments, the polymeric tubular member  160  may include a radiopaque marker band  166  (e.g.,  FIGS. 8-9 ) disposed within the distal portion  164  of the polymeric tubular member  160  and/or proximate the junction between the proximal portion  162  and the distal portion  164 . In some embodiments, the radiopaque marker band  166  may be embedded within a wall of the polymeric tubular member  160 . In some embodiments, the radiopaque marker band  166  may be secured within the lumen of the polymeric tubular member  160  such as with adhesive, friction fit, and/or interference fit. Some suitable materials for the radiopaque marker band  166  are discussed below. 
     The method of manufacturing the elongate shaft  110  may include fixedly attaching the proximal coupler  172  of the release mechanism  170  to a distal end of a longitudinal support filament  176 , as seen in  FIG. 5 . In at least some embodiments, the proximal coupler  172  of the release mechanism  170  may include an aperture  178  formed in a proximal portion thereof, the aperture  178  being configured to receive the distal end of the longitudinal support filament  176  therein. The distal end of the longitudinal support filament  176  may be fixedly attached to the proximal coupler  172  of the release mechanism  170  by, for example but not limited to adhesive bonding, welding, brazing, interference fit, friction fit, etc. as long as the resulting attachment is permanent. 
     In at least some embodiments, the longitudinal support filament  176  may be a metallic wire. In some embodiments, the longitudinal support filament  176  may have a substantially uniform outer diameter along its entire length. In one example, the longitudinal support filament  176  may have an outer diameter of about 0.0025 inches (about 0.0635 millimeters). In other examples, the longitudinal support filament  176  may have an outer diameter of about 0.0015 inches (about 0.0381 millimeters) to about 0.0035 inches (about 0.0889 millimeters). In one example, the longitudinal support filament  176  may be a tungsten-based alloy, or a nickel-cobalt or cobalt based alloy, such as 35N LT®. In some embodiments, the longitudinal support filament  176  may be capable of welding to and/or with platinum-iridium alloys. In some embodiments, the proximal coupler  172  and/or the distal coupler  174  may be formed from a platinum-iridium alloy. In some embodiments, the longitudinal support filament  176  resists corrosion with and/or when in contact with platinum-iridium alloys and nickel-titanium alloys. The longitudinal support filament  176  may have a high modulus of elasticity (e.g., greater than 33×10 6  pounds per square inch or 233 gigapascals) for stretch resistance, thereby allowing a smaller wire diameter to be used while achieving acceptable resistance to axial stretch and bending/flexibility characteristics. Other materials are also contemplated. 
     As shown in  FIG. 6 , the method may include inserting a proximal end of the longitudinal support filament  176  between the polymeric sheath  150  and the polymeric tubular member  160  proximate the distal ends of the polymeric sheath  150  and the polymeric tubular member  160  to position the longitudinal support filament  176  alongside the distal portion  146  of the second portion  140  of the metallic tubular member  120  (e.g.,  FIGS. 8 and 9 ) and the distal portion of the polymeric sheath  150 . Inserting the proximal end of the longitudinal support filament  176  between the polymeric sheath  150  and the polymeric tubular member  160  may include advancing the proximal end of the longitudinal support filament  176  proximally between the polymeric sheath  150  and the polymeric tubular member  160  until the proximal end of the longitudinal support filament  176  axially overlaps and is positioned radially outward of the distal portion  146  of the second portion  140  of the metallic tubular member  120  (e.g.,  FIGS. 8 and 9 ). In some embodiments, the longitudinal support filament  176  may be oriented substantially parallel to the central longitudinal axis of the elongate shaft  110 . 
     In some embodiments, after inserting the longitudinal support filament  176  between the polymeric sheath  150  and the polymeric tubular member  160  (and/or before reflowing the polymeric tubular member  160 , as discussed herein), the method may include engaging and/or abutting a proximal end and/or a proximal face of the proximal coupler  172  of the release mechanism  170  with and/or against the distal end of the polymeric sheath  150 , as shown in partial cutaway in  FIG. 7 . In some embodiments, after inserting the longitudinal support filament  176  between the polymeric sheath  150  and the polymeric tubular member  160  (and/or before reflowing the polymeric tubular member  160 , as discussed herein), the proximal portion of the longitudinal support filament  176  may extend proximal of the distal portion  146  of the second portion  140  of the metallic tubular member  120  and/or alongside the tapered portion  144  of the second portion  140  of the metallic tubular member  120 , as shown in  FIG. 8 . In  FIG. 8 , the longitudinal support filament  176  is shown as a solid line merely for illustrative and clarity purposes. As discussed above, in at least some embodiments, the polymeric tubular member  160  may include the radiopaque marker band  166 , as seen in  FIGS. 8 and 9 . 
       FIG. 9  illustrates that in some embodiments, after inserting the longitudinal support filament  176  between the polymeric sheath  150  and the polymeric tubular member  160  (and/or before reflowing the polymeric tubular member  160 , as discussed herein), the method may include positioning a tubular heat shrink member  20  over the polymeric tubular member  160 . In  FIG. 9 , the longitudinal support filament  176  is shown as a solid line merely for illustrative and clarity purposes. The method may include reflowing the polymeric tubular member  160  to secure the longitudinal support filament  176  relative to the polymeric sheath  150  and the metallic tubular member  120 , as shown in  FIG. 10 . Reflowing the polymeric tubular member  160  may include applying heat to the tubular heat shrink member  20  and the polymeric tubular member  160  disposed therein. The tubular heat shrink member  20  may be configured to return to a smaller diameter upon exposure to sufficient heat, thereby applying radially inward pressure upon the polymeric tubular member  160  as the heat softens and/or melts the polymeric tubular member  160 , thereby causing reflow of the polymeric tubular member  160  around the polymeric sheath  150 , the radiopaque marker band  166 , the longitudinal support filament  176 , and the distal portion  146  of the second portion  140  of the metallic tubular member  120 . The method may further include, before reflowing the polymeric tubular member  160 , trimming the longitudinal support filament  176  proximate the proximal end of the polymeric tubular member  160 , as seen in  FIG. 10 . 
     In some examples, after reflowing the polymeric tubular member  160 , the tubular heat shrink member  20  may be removed from the elongate shaft  110 . In some examples, after reflowing the polymeric tubular member  160 , a distal portion of the longitudinal support filament  176  is positioned directly against the outer surface of the distal portion of the polymeric sheath  150 . In some examples, after reflowing the polymeric tubular member  160 , a proximal portion of the longitudinal support filament  176  is positioned directly against an outer surface of the distal portion  146  of the second portion  140  of the metallic tubular member  120 , as seen in  FIG. 11 . In some examples, after reflowing the polymeric tubular member  160 , a proximal-most end of the polymeric tubular member  160  is disposed distal of the distally tapered portion  144  of the second portion  140  of the metallic tubular member  120 . In some examples, after reflowing the polymeric tubular member  160 , the proximal-most end of the polymeric tubular member  160  may be rounded toward the distal portion  146  of the second portion  140  of the metallic tubular member  120 . In some examples, after reflowing the polymeric tubular member  160 , the proximal-most end of the polymeric tubular member  160  extends proximal of a proximal end of the longitudinal support filament  176 , as seen in  FIG. 11 . In some examples, after reflowing the polymeric tubular member  160 , the proximal end of the polymeric tubular member  160  may pinch or squeeze the proximal end of the longitudinal support filament  176  against the distal portion  146  of the second portion  140  of the metallic tubular member  120 . 
     In some examples, after reflowing the polymeric tubular member  160 , the method may include applying a hydrophobic coating  168  to the outer surface of the polymeric tubular member  160  and/or to exposed portions of the outer surface of the metallic tubular member  120 . In some embodiments, after reflowing the polymeric tubular member  160 , the method may include removing the mandrel  10  from the lumen of the polymeric sheath  150 . Thereafter, the method may include disposing a release wire  186  axially within the lumen of the polymeric sheath  150 , and through the proximal coupler  172  and the distal coupler  174  to releasably couple the medical device  180  to the proximal coupler  172  and/or the elongate shaft  110 , as shown in  FIG. 12 . In some embodiments, the release wire  186  may be a metallic wire with limited axial stretching capability. Some suitable but non-limiting materials for the release wire  186  are described below. In some embodiments, disposing the release wire  186  within the lumen of the polymeric sheath  150  may include inserting a distal end of the release wire  186  into a proximal end of the polymeric sheath  150  and/or a proximal end of the metallic tubular member  120 , advancing the distal end of the release wire  186  distally within the lumen of the polymeric sheath  150 , through the proximal coupler  172 , and into engagement with and/or into the distal coupler  174 . 
     Thereafter, the method may include crimping or swaging the first portion  130  of the metallic tubular member  120  onto the release wire  186  to fixedly secure the release wire  186  to the first portion  130  of the metallic tubular member  120 , as seen in partial cutaway in  FIG. 12 . Crimping or swaging the first portion  130  of the metallic tubular member  120  onto the release wire  186  may include forcing an inner surface of the wall of the metallic tubular member  120  into contact with the outer surface of the release wire  186 . In some embodiments, crimping or swaging the first portion  130  of the metallic tubular member  120  onto the release wire  186  may include reducing the outer diameter of the release wire  186  within a crimped area to create a mechanical interlock between the metallic tubular member  120  and the release wire  186 . 
     In some examples, the first portion  130  of the metallic tubular member  120  may be disposed proximal of the pre-defined break region  122  and the second portion  140  of the metallic tubular member  120  may be disposed distal of the pre-defined break region  122 . In some examples, the first portion  130  of the metallic tubular member  120  may be integrally formed with the second portion  140  of the metallic tubular member  120  as a unitary and/or monolithic structure. The pre-defined break region  122  may be formed in the wall of the metallic tubular member  120 . In some examples, the pre-defined break region  122  may include a plurality of slits and/or notches formed in the wall of the metallic tubular member  120 . Other configurations are contemplated. For example, the pre-defined break region  122  may include a perforation, a plurality of apertures extending through the wall of the metallic tubular member  120 , a thinned or weakened feature or features formed in the wall of the metallic tubular member  120 , etc. The first portion  130  of the metallic tubular member  120  may be configured to disengage from the second portion  140  of the metallic tubular member  120  at the pre-defined break region  122 . However, regardless of form, the pre-defined break region  122  may generally be strong enough to avoid and/or prevent accidental or unintended disengagement of the first portion  130  of the metallic tubular member  120  from the second portion  140  of the metallic tubular member  120  in normal use and/or handling of the medical device system and/or the elongate shaft  110 . 
     As seen in  FIG. 12 , the medical device system may include the release wire  186  disposed within the lumen of the metallic tubular member  120 , the polymeric sheath  150  (not shown), and/or the elongate shaft  110 . The release wire  186  may be configured to releasably attach the medical device  180  to the distal end of the elongate shaft  110  in a first position, as seen in  FIG. 12  for example. In some embodiments, the release wire  186  may be alternately and/or interchangeably referred to as a pull wire, an actuation wire, and/or a locking wire. The release wire  186  may generally be a solid wire or shaft but may also be tubular in some embodiments. As discussed herein, the first portion  130  of the metallic tubular member  120  may be fixedly attached to a proximal portion of the release wire  186  proximal of the pre-defined break region  122 . 
     In use, the microcatheter  190  (e.g.,  FIG. 1 ) of the medical device system may be inserted into a patient&#39;s anatomy and a distal end thereof guided and/or advanced to a location adjacent a treatment site. The medical device  180  disposed at the distal end of the elongate shaft  110  may be advanced through the microcatheter  190  to the treatment site. In some embodiments, the medical device  180  may be disposed within the lumen of the microcatheter  190  proximate to the distal end of the elongate shaft  110 . In some embodiments, the medical device  180  may be disposed within the lumen of the microcatheter  190  proximate to the distal end of the elongate shaft  110  prior to use and/or prior to inserting the microcatheter  190  into the patient&#39;s anatomy. Deployment and/or release of the medical device  180  may be performed selectively depending upon the type of medical device and/or the desired treatment process or method. The elongate shaft  110  may have sufficient length that the proximal end of the elongate shaft  110  remains proximal of (e.g., extend proximally from) the microcatheter  190  when the medical device  180  is disposed distal of the microcatheter  190 . In use, the elongate shaft  110  may have sufficient length to reach from the treatment site to a position outside of the patient where the medical device system may be manipulated by the user. 
     When the user is ready to detach and/or release the medical device  180  from the elongate shaft  110  (e.g., when the medical device  180  has been positioned at the target site), the user may hold the second portion  140  of the metallic tubular member  120  to prevent movement of the second portion  140  of the metallic tubular member  120  and the user may bend the first portion  130  of the metallic tubular member  120  relative to the second portion  140  of the metallic tubular member  120  to thereby apply a moment around the pre-defined break region  122 . This moment may cause a break to form in the metallic tubular member  120  at the pre-defined break region  122 , thereby disengaging the first portion  130  of the metallic tubular member  120  from the second portion  140  of the metallic tubular member  120 . 
     Disengaging the first portion  130  of the metallic tubular member  120  from the second portion  140  of the metallic tubular member  120  permits the release wire  186  to axially translate and/or move relative to a distal portion of the elongate shaft  110 , the release mechanism  170 , and/or the medical device  180 . As such, the release wire  186  is translatable and/or movable to a second position when the second portion  140  of the metallic tubular member  120  is disengaged from the first portion  130  of the metallic tubular member  120 . With the release wire  186  in the second position, the medical device  180  may be detachable from the proximal coupler  172  of the release mechanism  170  and/or the distal end of the elongate shaft  110 . Accordingly, axial and/or proximal translation and/or movement of the first portion  130  of the metallic tubular member  120  relative to the second portion  140  of the metallic tubular member  120  may proximally retract the release wire  186  to the second position, thereby releasing the distal coupler  174  of the release mechanism  170  and/or the medical device  180  from the proximal coupler  172  of the release mechanism  170  and/or the distal end of the elongate shaft  110 . 
       FIGS. 13-17  illustrate aspects of another example method of manufacturing an elongate shaft for delivering the medical device  180 . While the method refers to an elongate shaft  210  (e.g.,  FIGS. 15-16 ), it shall be understood that the elongate shaft  210  may be used and/or referred to interchangeably with the elongate shaft  110  in the medical device system. Components and/or elements independent of the construction of the elongate shaft (e.g., the medical device  180 , the microcatheter  190 , etc.) may be the same as those described above, and not all elements are shown in each figure. Similarly, some of the same components and/or elements used in constructing the elongate shaft  110  (e.g., the release mechanism  170 , the release wire  186 , etc.) may also be used in construction of the elongate shaft  210 , and thus the same reference numbers are used and the description of those elements is not repeated in the interest of brevity. 
     As shown in  FIG. 13 , the method may include extruding a polymeric tubular member  260  and a longitudinal support filament  176  over a first polymeric sheath  252  disposed on a mandrel  30  to form a composite tubular member  258 . In some embodiments, as may be seen in  FIG. 13 , the longitudinal support filament  176  may be fed through an extrusion machine  40  alongside the first polymeric sheath  252  disposed on the mandrel  30 . In some embodiments, the longitudinal support filament  176  may be extruded at the same time as the polymeric tubular member  260  and/or may be co-extruded with the polymeric tubular member  260 . 
     In some embodiments, the first polymeric sheath  252  may be formed directly on the mandrel  30 . For example, the first polymeric sheath  252  may be extruded onto the mandrel  30 . In another example, the first polymeric sheath  252  may be formed as a tubular structure and the mandrel  30  may be inserted into the first polymeric sheath  252  (or the first polymeric sheath  252  may be slid over the mandrel  30 ). In one example, the first polymeric sheath  252  may have an outer diameter of about 0.006 inches (about 0.1524 millimeters). In other examples, the first polymeric sheath  252  may have an outer diameter of about 0.004 inches (0.1016 millimeters) to about 0.008 inches (about 0.2032 millimeters). The mandrel  30  may be removable from the first polymeric sheath  252 , as discussed herein. In some embodiments, the mandrel  30  may be slidable with respect to the first polymeric sheath  252 . In some embodiments, the first polymeric sheath  252  may have a slight friction fit and/or a slight interference fit with the mandrel  30  (e.g., the mandrel  30  may not move freely relative to the first polymeric sheath  252 ) that may be overcome at a later time to remove the mandrel  30  from the lumen of the first polymeric sheath  252 . In one example, the first polymeric sheath  252  may be formed from polytetrafluoroethylene (PTFE). Other materials are also contemplated. In at least some embodiments, an outer surface of the first polymeric sheath  252  may be etched and/or otherwise mechanically or chemically treated to facilitate bonding and/or securement to another material. 
     In some embodiments, the polymeric tubular member  260  may include a proximal portion comprising a first polymeric material and a distal portion comprising a second polymeric material. In at least some embodiments, the first polymeric material may be different from the second polymeric material. In some embodiments, the proximal portion and the distal portion may be bonded, melted, comingled, co-extruded, reflowed, or otherwise permanently joined together to render the polymeric tubular member as a single unitary and/or monolithic structure. In some embodiments, the first polymeric material may be a polyamide 12, such as VESTAMID® L, and the second polymeric material may be a polyether block amide, such as PEBAX®. In one example, the first polymeric material may be VESTAMID® L2101F and the second polymeric material may be PEBAX® 63D. Other materials and/or combinations of materials are also contemplated. In at least some embodiments, the second polymeric material may be softer and/or more flexible than the first polymeric material. 
     In some embodiments, the polymeric tubular member  260  may have an overall length of about 15 centimeters (cm), about 20 cm, about 24 cm, about 26 cm, about 26.5 cm, about 27 cm, about 30 cm, about 35 cm, or another suitable overall length depending upon the intended procedure. In one example, the proximal portion may have a length of about 22 cm and the distal portion may have a length of about 4.5 cm. In other examples, the proximal portion may have a length of about 10 cm to about 30 cm and the distal portion may have a length of about 3 cm to about 6 cm. In some embodiments, the polymeric tubular member  260  may have a substantially uniform outer diameter and/or a substantially uniform inner diameter throughout its entire length, including the proximal portion and the distal portion. However, other configurations, including but not limited to tapered and/or stepped configurations, are also contemplated. In one example, the polymeric tubular member  260  may have an outer diameter of about 0.016 inches (about 0.4064 millimeters). In other examples, the polymeric tubular member  160  may have an outer diameter of about 0.014 inches (about 0.3556 millimeters) to about 0.018 inches (about 0.4572 millimeters). 
     In at least some embodiments, the polymeric tubular member  260  may include a radiopaque marker band disposed within the distal portion of the polymeric tubular member  260  and/or proximate the junction between the proximal portion and the distal portion. In some embodiments, the radiopaque marker band may be fed through the extrusion machine  40  over the first polymeric sheath  252  and the longitudinal support filament  176  during formation of the composite tubular member  258  to embed the radiopaque marker within a wall of the polymeric tubular member  260  and/or the composite tubular member  258 . In some embodiments, the radiopaque marker may be secured to an outer surface of the polymeric tubular member  260 . In some embodiments, the radiopaque marker may be secured to the outer surface of the distal portion of the polymeric tubular member  260 . In some embodiments, the radiopaque marker may be secured to the outer surface of the polymeric tubular member  260  adjacent to and/or at the junction between the proximal portion and the distal portion of the polymeric tubular member  260 . In some embodiments, the radiopaque marker may be fixedly secured to the outer surface of the polymeric tubular member  260 . For example, the radiopaque marker may be adhesively bonded to the outer surface of the polymeric tubular member  260 , crimped and/or swaged onto the outer surface of the polymeric tubular member  260 , and/or fixedly secured to the outer surface of the polymeric tubular member  260  using a heat shrink element. Other configurations and/or methods of adding a radiopaque marker to the composite tubular member  258  are also contemplated. 
     In some examples, after extruding the polymeric tubular member  260  over the first polymeric sheath  252  and/or after forming the composite tubular member  258 , the polymeric tubular member  260  may be fixedly and permanently attached (e.g., bonded, comingled, coextruded, etc.) to the first polymeric sheath  252 . In some examples, after extruding the polymeric tubular member  260  over the first polymeric sheath  252  and/or after forming the composite tubular member  258 , the longitudinal support filament  176  may be embedded within and/or surrounded by the polymeric tubular member  260  and/or the composite tubular member  258 . In some examples, after extruding the polymeric tubular member  260  over the first polymeric sheath  252  and/or after forming the composite tubular member  258 , the longitudinal support filament  176  may be positioned in direct contact with the first polymeric sheath  252  and/or the polymeric tubular member  260 . 
     The method may include sliding a metallic tubular member  120  over a second polymeric sheath  254  or sliding the second polymeric sheath  254  into a lumen of the metallic tubular member  120 . In one example, the second polymeric sheath  254  may have an outer diameter of about 0.006 inches (about 0.1524 millimeters). In other examples, the second polymeric sheath  254  may have an outer diameter of about 0.004 inches (0.1016 millimeters) to about 0.008 inches (about 0.2032 millimeters). In one example, the second polymeric sheath  254  may be formed from polytetrafluoroethylene (PTFE). Other materials are also contemplated. In at least some embodiments, an outer surface of the second polymeric sheath  254  may be etched and/or otherwise mechanically or chemically treated to facilitate bonding and/or securement to another material. In some embodiments, the second polymeric sheath  254  may be formed and/or inserted using a mandrel, similar to the first polymeric sheath  252  above. The metallic tubular member  120  may be the same metallic tubular member  120  used and described above, and thus the physical characteristics of the metallic tubular member  120  are not repeated. The method may include securing a distal end of the second polymeric sheath  254  to a distal end and/or to the distal portion  146  of the second portion  140  of the metallic tubular member  120 , as shown in  FIG. 14 . In some embodiments, the method may further include trimming excess length off of the second polymeric sheath  254  such that a distal end of the second polymeric sheath  254  is coterminal with the distal end of the metallic tubular member  120 . 
     The method may include placing the composite tubular member  258 , with the mandrel  30  removed, over the distal portion  146  of the second portion  140  of the metallic tubular member  120 . In some embodiments, a proximal portion of the first polymeric sheath  252  may be removed from within the composite tubular member  258  before placing the composite tubular member  258  over the distal portion  146  of the second portion  140  of the metallic tubular member  120 , as seen in  FIG. 15 . In some embodiments, a distal portion of the first polymeric sheath  252  is removed from within the composite tubular member  258  before placing the composite tubular member  258  over the distal portion  146  of the second portion  140  of the metallic tubular member  120 . In some embodiments, the distal portion of the first polymeric sheath  252  is removed from within the composite tubular member  258  after placing the composite tubular member  258  over the distal portion  146  of the second portion  140  of the metallic tubular member  120 . 
     In some examples, prior to placing the composite tubular member  258  over the distal portion  146  of the second portion  140  of the metallic tubular member  120 , the longitudinal support filament  176  may extend proximal of the polymeric tubular member  260  and/or the first polymeric sheath  252 . In some embodiments, the distal portion of the first polymeric sheath  252  is removed from within the composite tubular member  258 , the longitudinal support filament  176  may extend distal of the first polymeric sheath  252 . 
     The method may include positioning a tubular heat shrink member  50  over a proximal portion of the polymeric tubular member  260  and at least a portion of the distal portion  146  of the second portion  140  of the metallic tubular member  120 , as seen in  FIG. 16 . The method may include reflowing the proximal portion of the polymeric tubular member  260  of the composite tubular member  258  onto the distal portion  146  of the second portion  140  of the metallic tubular member  120  to secure the longitudinal support filament  176  relative to the metallic tubular member  120 . In some embodiments, reflowing the polymeric tubular member  260  may include applying heat to the tubular heat shrink member  50  and the polymeric tubular member  260  disposed therein. The tubular heat shrink member  50  may be configured to return to a smaller diameter upon exposure to sufficient heat, thereby applying radially inward pressure upon the polymeric tubular member  260  as the heat softens and/or melts the polymeric tubular member  260 , thereby causing reflow of the polymeric tubular member  260  around the first polymeric sheath  250 , the longitudinal support filament  176 , and the distal portion  146  of the second portion  140  of the metallic tubular member  120 . The method may further include, before reflowing the polymeric tubular member  260 , trimming the longitudinal support filament  176  proximate the proximal end of the polymeric tubular member  260 . Reflowing the polymeric tubular member  260  may result in the structure shown in  FIG. 11 . 
     In some examples, after reflowing the proximal portion of the polymeric tubular member  260  (e.g.,  FIG. 16 ), the tubular heat shrink member  50  may be removed from the proximal portion of the polymeric tubular member  260 . In some examples, after reflowing the proximal portion of the polymeric tubular member  260 , a proximal portion of the longitudinal support filament  176  is positioned directly against an outer surface of the distal portion  146  of the second portion  140  of the metallic tubular member  120 , resulting in a configuration similar to the configuration shown in  FIG. 11 . As such, reflowing the proximal portion of the polymeric tubular member  260  may secure the longitudinal support filament  176  against the outer surface of the distal portion  146  of the second portion  140  of the metallic tubular member  120 . In some examples, after reflowing the proximal portion of the polymeric tubular member  260 , a proximal-most end of the polymeric tubular member  260  is disposed distal of the distally tapered portion  144  of the second portion  140  of the metallic tubular member  120 . In some examples, after reflowing the proximal portion of the polymeric tubular member  260 , the proximal-most end of the polymeric tubular member  260  may be rounded toward the distal portion  146  of the second portion  140  of the metallic tubular member  120 . In some embodiments, after reflowing the proximal portion of the polymeric tubular member  260 , the proximal-most end of the polymeric tubular member  260  extends proximal of a proximal end of the longitudinal support filament  176 . In some examples, after reflowing the proximal portion of the polymeric tubular member  260 , the proximal end of the polymeric tubular member  260  may pinch or squeeze the proximal end of the longitudinal support filament  176  against the distal portion  146  of the second portion  140  of the metallic tubular member  120 . 
     The method may further include fixedly attaching the proximal coupler  172  to the distal end of the longitudinal support filament  176 . In at least some embodiments, a distal portion of the polymeric tubular member  260  may be removed to expose the distal end of the longitudinal support filament  176  prior to fixedly attaching the proximal coupler  172 , as seen in  FIG. 17 . In some embodiments, prior to fixedly attaching the proximal coupler  172  to the distal end of the longitudinal support filament  176 , the method may include trimming the distal end of the longitudinal support filament  176  such that the distal end of the longitudinal support filament  176  cannot extend distally through and/or from the proximal coupler  172 . In some embodiments, after fixedly attaching the proximal coupler  172  to the distal end of the longitudinal support filament  176 , the method may include trimming the distal end of the longitudinal support filament  176  such that the distal end of the longitudinal support filament  176  does not extend distally through and/or from the proximal coupler  172 . 
     In some examples, after reflowing the proximal portion of the polymeric tubular member  260 , the method may include applying a hydrophobic coating  168  to the outer surface of the polymeric tubular member  260  and/or to exposed portions of the outer surface of the metallic tubular member  120 . Next, the method may include disposing a release wire  186  axially within the lumen of the first polymeric sheath  252  and the second polymeric sheath  254 , and through the proximal coupler  172  and the distal coupler  174  to releasably couple the medical device  180  to the proximal coupler  172  and/or the elongate shaft  210 , similar to the configuration shown in  FIG. 12 . In some examples, disposing the release wire  186  within the lumen of the first polymeric sheath  252  and the second polymeric sheath  254  may include inserting a distal end of the release wire  186  into a proximal end of the first polymeric sheath  252  and/or a proximal end of the metallic tubular member  120 , advancing the distal end of the release wire  186  distally within the lumen of the first polymeric sheath  252  and the second polymeric sheath  254 , through the proximal coupler  172 , and into engagement with and/or into the distal coupler  174 . Next, the method may include crimping or swaging the first portion  130  of the metallic tubular member  120  onto the release wire  186  to fixedly secure the release wire  186  to the first portion  130  of the metallic tubular member  120  as described above with respect to  FIG. 12 . 
       FIGS. 18 and 19  illustrate an alternative configuration of an elongate shaft  310  for delivering the medical device  180  (not shown). The elongate shaft  310  may be formed and/or manufactured using any of the methods described herein. The elongate shaft  310  may include a polymeric sheath  350  having a lumen extending therethrough. The elongate shaft  310  may include a metallic tubular member  320  disposed over a proximal portion of the polymeric sheath  350 , in a manner consistent with the configuration(s) described herein with respect to the elongate shaft  110 . In at least some embodiments, the metallic tubular member  320  may be constructed and/or may have physical characteristics similar to or the same as the metallic tubular member  120  described herein, and said description is not repeated. The elongate shaft  310  may include a polymeric tubular member  360  disposed over a distal portion of the polymeric sheath  350  and a distal portion of the metallic tubular member  320 , in a manner consistent with the configuration(s) described herein with respect to the elongate shaft  110 . The elongate shaft  310  may include the longitudinal support filament  176  extending along the distal portion of the polymeric sheath  350  and the distal portion of the metallic tubular member  320 , in a manner consistent with the configuration(s) described herein with respect to the elongate shaft  110 . The elongate shaft  310  may include the proximal coupler  172  fixedly attached to the distal end of the longitudinal support filament  176 , in a manner consistent with the configuration(s) described herein with respect to the elongate shaft  110 . 
     In some examples, the polymeric tubular member  360  may secure the longitudinal support filament  176  relative to the polymeric sheath  350  and the metallic tubular member  320 , in a manner consistent with the configuration(s) described herein with respect to the elongate shaft  110 . The polymeric tubular member  360  may include a proximal portion  362 , a distal portion  366 , and a middle portion  364  disposed longitudinally between the proximal portion  362  and the distal portion  366 . In at least some embodiments, the middle portion  364  may extend continuously from the proximal portion  362  to the distal portion  366 . The middle portion  364  may have a lower bending stiffness than the proximal portion  362  and the distal portion  366 . For example, the proximal portion  362  may be formed from a first material, the middle portion  364  may be formed from a second material, and the distal portion  366  may be formed from a third material. In some embodiments, the second material may be different from the first material and/or the third material. In some embodiments, the third material may be the first material. Other configurations are also contemplated. Accordingly, the middle portion  364  may define a preferential bending location of the elongate shaft  310 , as seen in  FIG. 19 . 
     The longitudinal support filament  176  may extend within the proximal portion  362 , the middle portion  364 , and the distal portion  366  of the polymeric tubular member  360 . As such, the longitudinal support filament  176  may substantially limit and/or prevent axial stretching of the polymeric tubular member  360  and/or the elongate shaft  310 . While the second material of the polymeric tubular member  360  may be more susceptible to axial stretch due to its lower bending stiffness than the first material and the third material, the longitudinal support filament  176  may have a high modulus of elasticity as discussed herein, thereby limiting and/or preventing axial stretch of the elongate shaft  310  within the middle portion  364  of the polymeric tubular member  360 . In some embodiments, the radial and/or circumferential location of the longitudinal support filament  176  may further define preferential bending characteristics of the elongate shaft  310 , such as direction of bending relative to the central longitudinal axis of the elongate shaft  310 . 
       FIG. 20  is a cross-sectional view illustrating one example configuration of the longitudinal support filament  176  within the elongate shaft  110 . The cross-section shown in  FIG. 20  may be taken at a location distal of the metallic tubular member  120  and proximal of the proximal coupler  172 . As described herein, the longitudinal support filament  176  may be in direct contact with the polymeric sheath  150  and/or the polymeric tubular member  160 . In some embodiments, the longitudinal support filament  176  may be embedded within and/or surrounded by the polymeric tubular member  160  alongside the polymeric sheath  150 . Other configurations consistent with the instant disclosure are also contemplated. The skilled person will recognize that the configuration may be applied in any of the configurations of an elongate shaft (e.g., ref.  210 ,  310 ) disclosed herein. 
       FIG. 21  is a cross-sectional view illustrating an alternative configuration of the elongate shaft  110 . In the alternative configuration of  FIG. 21 , the elongate shaft  110  may include a plurality of longitudinal support filaments  176 . In the illustrated example, the plurality of longitudinal support filaments  176  includes three longitudinal support filaments circumferentially spaced apart around the polymeric sheath  150 . Though not expressly illustrated, other configurations including two longitudinal support filaments, four longitudinal support filaments, five longitudinal support filaments, six longitudinal support filaments, or another suitable number of longitudinal support filaments are also contemplated. In some embodiments, the plurality of longitudinal support filaments  176  may be circumferentially spaced apart equally around the polymeric sheath  150 . Such a configuration may prevent formation or introduction of preferential bending characteristics. In some embodiments, the plurality of longitudinal support filaments  176  may be arranged unequally and/or irregularly around the polymeric sheath  150 , so as to define and/or induce preferential bending characteristics. 
     The cross-section shown in  FIG. 21  may be taken at a location distal of the metallic tubular member  120  and proximal of the proximal coupler  172 . Similar to some configurations disclosed herein, the plurality of longitudinal support filaments  176  may be in direct contact with the polymeric sheath  150  and/or the polymeric tubular member  160 . In some embodiments, the plurality of longitudinal support filaments  176  may be embedded within and/or surrounded by the polymeric tubular member  160  alongside the polymeric sheath  150 . Other configurations consistent with the instant disclosure are also contemplated. The skilled person will recognize that the configuration may be applied in any of the configurations of an elongate shaft (e.g., ref.  210 ,  310 ) disclosed herein. 
     The materials that can be used for the various components of the delivery shaft (and/or other elements disclosed herein) and the various components thereof disclosed herein may include those commonly associated with medical devices. For simplicity purposes, the following discussion makes reference to the delivery shaft. However, this is not intended to limit the devices and methods described herein, as the discussion may be applied to other elements, members, components, or devices disclosed herein, such as, but not limited to, the elongate shaft, the release wire, the polymeric sheath, the metallic tubular member, the polymeric tubular member, the release mechanism, the longitudinal support filament, the microcatheter, etc. and/or elements or components thereof. 
     In some embodiments, the delivery shaft and/or other elements disclosed herein may be made from a metal, metal alloy, polymer (some examples of which are disclosed below), a metal-polymer composite, ceramics, combinations thereof, and the like, or other suitable material. Some examples of suitable metals and metal alloys include stainless steel, such as 444V, 444L, and 314LV 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: R44035 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: R44003 such as ELGILOY®, PHYNOX®, and the like); platinum enriched stainless steel; titanium; combinations thereof; and the like; or any other suitable material. 
     As alluded to herein, within the family of commercially available nickel-titanium or nitinol alloys, is a category designated “linear elastic” or “non-super-elastic” which, although may be similar in chemistry to conventional shape memory and super elastic varieties, may exhibit distinct and useful mechanical properties. Linear elastic and/or non-super-elastic nitinol may be distinguished from super elastic nitinol in that the linear elastic and/or non-super-elastic nitinol does not display a substantial “super-elastic plateau” or “flag region” in its stress/strain curve like super elastic nitinol does. Instead, in the linear elastic and/or non-super-elastic nitinol, as recoverable strain increases, the stress continues to increase in a substantially linear, or a somewhat, but not necessarily entirely linear relationship until plastic deformation begins or at least in a relationship that is more linear than the super elastic plateau and/or flag region that may be seen with super elastic nitinol. Thus, for the purposes of this disclosure linear elastic and/or non-super-elastic nitinol may also be termed “substantially” linear elastic and/or non-super-elastic nitinol. 
     In some examples, linear elastic and/or non-super-elastic nitinol may also be distinguishable from super elastic nitinol in that linear elastic and/or non-super-elastic nitinol may accept up to about 2-5% strain while remaining substantially elastic (e.g., before plastically deforming) whereas super elastic nitinol may accept up to about 8% strain before plastically deforming. Both of these materials can be distinguished from other linear elastic materials such as stainless steel (also distinguishable by its composition), which may accept only about 0.2 to 0.44 percent strain before plastically deforming. 
     In some examples, the linear elastic and/or non-super-elastic nickel-titanium alloy is an alloy that does not show any martensite/austenite phase changes that are detectable by differential scanning calorimetry (DSC) and dynamic metal thermal analysis (DMTA) analysis over a large temperature range. For example, in some embodiments, there may be no martensite/austenite phase changes detectable by DSC and DMTA analysis in the range of about-60 degrees Celsius (° C.) to about 120° C. in the linear elastic and/or non-super-elastic nickel-titanium alloy. The mechanical bending properties of such material may therefore be generally inert to the effect of temperature over this very broad range of temperature. In some embodiments, the mechanical bending properties of the linear elastic and/or non-super-elastic nickel-titanium alloy at ambient or room temperature are substantially the same as the mechanical properties at body temperature, for example, in that they do not display a super-elastic plateau and/or flag region. In other words, across a broad temperature range, the linear elastic and/or non-super-elastic nickel-titanium alloy maintains its linear elastic and/or non-super-elastic characteristics and/or properties. 
     In some embodiments, the linear elastic and/or non-super-elastic nickel-titanium alloy may be in the range of about 50 to about 60 weight percent nickel, with the remainder being essentially titanium. In some embodiments, the composition is in the range of about 54 to about 57 weight percent nickel. One example of a suitable nickel-titanium alloy is FHP-NT alloy commercially available from Furukawa Techno Material Co. of Kanagawa, Japan. Other suitable materials may include ULTANIUM™ (available from Neo-Metrics) and GUM METAL™ (available from Toyota). In some other embodiments, a superelastic alloy, for example a superelastic nitinol can be used to achieve desired properties. 
     In some examples, portions or all of the delivery shaft and/or other elements disclosed herein may also be doped with, made of, or otherwise include a radiopaque material. Radiopaque materials are understood to be materials capable of producing a relatively bright image on a fluoroscopy screen or another imaging technique during a medical procedure. This relatively bright image aids a user in determining the location of the delivery shaft and/or other elements disclosed herein. Some examples of radiopaque materials can include, but are not limited to, gold, platinum, palladium, tantalum, tungsten alloy, polymer material loaded with a radiopaque filler, and the like. Additionally, other radiopaque marker bands and/or coils may also be incorporated into the design of the delivery shaft and/or other elements disclosed herein to achieve the same result. 
     In some embodiments, a degree of Magnetic Resonance Imaging (MRI) compatibility is imparted into the delivery shaft and/or other elements disclosed herein. For example, the delivery shaft and/or components or portions thereof may be made of a material that does not substantially distort the image and create substantial artifacts (e.g., gaps in the image). Certain ferromagnetic materials, for example, may not be suitable because they may create artifacts in an MRI image. The delivery shaft or portions thereof, may also be made from a material that the MRI machine can image. Some materials that exhibit these characteristics include, for example, tungsten, cobalt-chromium-molybdenum alloys (e.g., UNS: R44003 such as ELGILOY®, PHYNOX®, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R44035 such as MP35-N® and the like), nitinol, and the like, and others. 
     In some examples, the delivery shaft and/or other elements disclosed herein may be made from or include a polymer or other suitable material. Some 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. 
     In some embodiments, the delivery shaft and/or other elements disclosed herein may include a fabric material disposed over or within the structure. The fabric material may be composed of a biocompatible material, such a polymeric material or biomaterial, adapted to promote tissue ingrowth. In some embodiments, the fabric material may include a bioabsorbable material. Some examples of suitable fabric materials include, but are not limited to, polyethylene glycol (PEG), nylon, polytetrafluoroethylene (PTFE, ePTFE), a polyolefinic material such as a polyethylene, a polypropylene, polyester, polyurethane, and/or blends or combinations thereof. 
     In some examples, the delivery shaft and/or other elements disclosed herein may include and/or be formed from a textile material. Some examples of suitable textile materials may include synthetic yarns that may be flat, shaped, twisted, textured, pre-shrunk or un-shrunk. Synthetic biocompatible yarns suitable for use in the present disclosure include, but are not limited to, polyesters, including polyethylene terephthalate (PET) polyesters, polypropylenes, polyethylenes, polyurethanes, polyolefins, polyvinyl s, polymethylacetates, polyamides, naphthalene dicarboxylene derivatives, natural silk, and polytetrafluoroethylenes. Synthetic yarns may be or may include a metallic yarn or a glass or ceramic yarn or fiber, such as yarns made from or containing stainless steel, platinum, gold, titanium, tantalum or a Ni—Co—Cr-based alloy. The yarns may further include carbon, glass or ceramic fibers. Desirably, the yarns are made from thermoplastic materials including, but not limited to, polyesters, polypropylenes, polyethylenes, polyurethanes, polynaphthalenes, polytetrafluoroethylenes, and the like. The yarns may be of the multifilament, monofilament, or spun types. The type and denier of the yarn chosen may be selected in a manner which forms a biocompatible and implantable prosthesis and, more particularly, a vascular structure having desirable properties. 
     In some embodiments, the delivery shaft and/or other elements disclosed herein may include and/or be treated with a suitable therapeutic agent. Some examples of suitable therapeutic agents may include anti-thrombogenic agents (such as heparin, heparin derivatives, urokinase, and PPack (dextrophenylalanine proline arginine chloromethyl ketone)); anti-proliferative agents (such as enoxaparin, angiopeptin, monoclonal antibodies capable of blocking smooth muscle cell proliferation, hirudin, and acetylsalicylic acid); anti-inflammatory agents (such as dexamethasone, prednisolone, corticosterone, budesonide, estrogen, sulfasalazine, and mesalamine); antineoplastic/antiproliferative/anti-mitotic agents (such as paclitaxel, 5-fluorouracil, cisplatin, vinblastine, vincristine, epothilones, endostatin, angiostatin and thymidine kinase inhibitors); anesthetic agents (such as lidocaine, bupivacaine, and ropivacaine); anti-coagulants (such as D-Phe-Pro-Arg chloromethyl ketone, an RGD peptide-containing compound, heparin, anti-thrombin compounds, platelet receptor antagonists, anti-thrombin antibodies, anti-platelet receptor antibodies, aspirin, prostaglandin inhibitors, platelet inhibitors, and tick antiplatelet peptides); vascular cell growth promoters (such as growth factor inhibitors, growth factor receptor antagonists, transcriptional activators, and translational promoters); vascular cell growth inhibitors (such as growth factor inhibitors, growth factor receptor antagonists, transcriptional repressors, translational repressors, replication inhibitors, inhibitory antibodies, antibodies directed against growth factors, bifunctional molecules consisting of a growth factor and a cytotoxin, bifunctional molecules consisting of an antibody and a cytotoxin); cholesterol-lowering agents; vasodilating agents; and agents which interfere with endogenous vasoactive mechanisms. 
     It should be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps, without exceeding the scope of the disclosure. This may include, to the extent that it is appropriate, the use of any of the features of one example embodiment being used in other embodiments. The disclosure&#39;s scope is, of course, defined in the language in which the appended claims are expressed.