The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which:
While the invention is 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 the invention 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 invention.
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” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In many instances, the terms “about” may include numbers that are rounded to the nearest significant figure.
The recitation of numerical ranges by endpoints includes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).
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.
The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention.
As will be appreciated, at least some embodiments relate to a medical device that includes a metallic tubular member disposed about and attached to a metallic core member. Medical devices incorporating such a structure could be guidewires or catheters or other such medical devices.
Refer now to
A distal tip member 37 may be disposed at the distal end 26 of the tubular member 20 and/or the distal end 16 of the guidewire 10. The distal tip member 37 may be any of a broad variety of suitable structures, for example, a solder tip, a weld tip, a pre-made or pre-formed metallic or polymer structure, or the like, that is attached or joined to the distal end of the tubular member 20 using a suitable attachment technique.
The guidewire 10 may also include a core member 30 that may be attached to the tubular member 20, and extend from a location within the tubular member 20 and/or from the proximal end 28 of the tubular member 20, for example, to the proximal end 18 of the guidewire 10. As can be appreciated, a portion of the core member 30 may extend into at least a portion of the lumen 34. In the embodiment shown, the core member 30 includes a distal portion 40 that extends within the lumen 34, and a proximal portion 42 that extends proximally from the tubular member 20. In the embodiments shown, the core member 30 ends proximally from the distal tip member 37 and/or proximally of the distal end 26 of the tubular member 20. In other embodiments, however, core member 30 may extend to, and be attached to the distal tip member 37.
The guidewire 10 may also include other structures, such as such as a shaping wire or ribbon, one or more coils, marker members, or the like, or others, but such structures are not necessary in some other embodiments. In the embodiment shown, the guidewire 10 includes a distal coil member 36 and a shaping ribbon member 38 that may be, for example, attached to and extend distally from the distal end of the core wire 30, and may be attached, for example, to the tip member 37. The materials used for such structures can be any that are suitable for their intended purpose. Some example materials are discussed below. Additionally, the attachment of the various components can be achieved using any suitable attachment techniques, some examples of which may include adhesive bonding, welding, soldering, brazing, mechanical bonding and/or fitting, or the like, or any other suitable technique.
In at least some embodiments, however, an end, such as the proximal end 28, of the tubular member 20 can be attached to the core member 30 with a “fillet weld” 44. In some cases a fillet weld (pronounced “FILL-it,” not “fil-LAY”) can be characterized as a weld used to make lap joints, corner joints, and T joints. The fillet weld 44 may be roughly and/or generally triangular and/or ramp-like and/or wedge-like in cross-section, although its shape is not always a right triangle or an isosceles triangle, or not necessarily an exact triangle. For example, one or more of the sides may be curvilinear and/or ramp-like. In making a fillet weld, weld metal can be deposited in a corner formed by the fit-up of the two members (for example, the core member 30 and the tubular member 20) and can penetrate and fuse with the base metals of the two members to form the joint. Note that for the sake of clarity, the drawings do not show the penetration of the weld metal, but such penetration may, and in fact, is likely to exist. The use of such a fillet weld 44 may provide for certain advantages in some embodiments.
For example, refer now to
The use of filet welding techniques can provide a desired alternative. For example, referring back to
Referring again to
Refer now to
The weld 44 can be created using any suitable welding techniques and/or equipment. Some examples of welding processes which may be suitable in some applications include LASER welding, resistance welding, TIG welding, microplasma welding, electron beam, and friction or inertia welding. Some examples of LASERs that may be suitable for LASER welding may include a Nd:YAG LASER, a CO2 LASER, a Diode LASER, or the like, or others. LASER welding equipment which may be suitable in some applications is commercially available from Unitek Miyachi of Monrovia, Calif. and Rofin-Sinar Incorporated of Plymouth, Mich. Resistance welding equipment which may be suitable in some applications is commercially available from Palomar Products Incorporated of Carlsbad, Calif. and Polaris Electronics of Olathe, Kans. TIG welding equipment which may be suitable in some applications is commercially available from Weldlogic Incorporated of Newbury Park, Calif. Microplasma welding equipment which may be suitable in some applications is commercially available from Process Welding Systems Incorporated of Smyrna, Tenn.
In some example embodiments, the welding process is achieved by using a LASER welder, such as a Nd:YAG LASER. The core member 30 is disposed within the tubular member 20 such that the corner 43 is formed, and the LASER is directed at the corner 43. The LASER is set to pulse at a predetermined number of pulses per second, and the guidewire assembly is rotated at a given speed. The LASER is then activated. As the LASER hits the corner 43 (the proximal end 28 of the tube 20 and the adjacent outer surface of the core 30) it forms a fillet weld 44 around the entire circumference of the core 30 and tube 20. This joins the tube 20 to the core 30, and creates a smooth transition or ramp between the two structures. In some embodiments, the assembly can be rotated at a speed in the range of about 5 to about 15 RPM, and the LASER can be set to pulse in the range of about 1 to about 10 pulses per second, for a total number of pulses in the range of about 10 to about 50 total pulses.
As indicated above, the weld 44 may have a generally triangular and/or ramp like cross sectional shape and may join two surfaces (for example, the end surface of the tubular member 20 and the outer surface of the core wire 30) that meet in an interior angle. In some embodiments, the difference in size between the outer diameters of the proximal end of the tubular member 20 and the outer surface of the core wire 30 can be in the range of about 0.001 inch to about 0.2 inch, or in some embodiments, in the range of about 0.01 inch to about 0.08 inch. As such, the weld 44 may have a leg extending along the proximal end surface of the tubular member 20 that is in the range of about 0.01 inch to about 0.2 inch, or in some embodiments, in the range of about 0.01 inch to about 0.08 inch. Further, the weld 44 may include a leg that extends along the outer surface of the core wire 30 (in other words, the length of the weld as it extends along the longitudinal axis of the core wire) that is in the range of about 0.001 inch to about 0.2 inch, or in some embodiments, in the range of about 0.003 inch to about 0.03 inch. The tapered leg of the weld (for example, the leg that may be generally characterized as the hypotenuse of the generally triangular shaped weld) may have a length in the range of about 0.001 inch to about 0.2 inch, or in some embodiments, in the range of about 0.003 to about 0.03 inch. It should be understood, however, that there dimensions are by way of example only, and that a broad variety of other dimensions may be used.
As indicated above, the weld 44 can penetrate and fuse with the base metals of the core member 30 and the tubular member 20 to form the joint. The degree of penetration may be any suitable amount given the desired quality of the weld. In some embodiments, the degree of penetration within the material of the tubular member may be in the range of about 5% to about 100%, and the degree of penetration within the material of the core wire may be in the range of about 5% to about 100%.
It should also be understood that additional attachment points between the tubular member 20 and the core member 30 and/or other components of the guidewire 10 may be provided using any suitable attachment techniques, including any of those disclosed herein. Such additional attachment can be made in any suitable manner and at any suitable location, as desired and/or necessary. For example, the tubular member 20 may be connected to the core member 30, coil 36 and/or shaping ribbon 37 through the use of a solder tip 37. Those of skill in the art and others, however, will recognize that any of a broad variety of attachment techniques and/or structures may be used.
Another embodiment is shown in
A wide variety of materials and alternative features can also be used with any of the embodiments described herein. A description of some of these materials and alternative features with respect to at least some of the embodiments discussed above is given below. However, it should also be understood that any of these materials and/or alternative features can also be incorporated into any of the other embodiments described herein. The materials that can be used for the various components of guidewire 10 may include any that would serve the intended purpose and/or function. For example, core member 30, tubular member 20, coils 36 and 120, and/or shaping ribbon 38 may be made from a metal, metal alloy, a metal-polymer composite, and the like, or any other suitable material. Some examples of suitable metals and metal alloys include stainless steel, such as 304V, 304L, and 316LV stainless steel; mild steel; nickel-titanium alloy such as linear-elastic or super-elastic nitinol, nickel-chromium alloy, nickel-chromium-iron alloy, cobalt alloy, tungsten or tungsten alloys, a nickel-based alloy, such as a hastelloy, a nickel-cobalt based alloy, such as MP35-N, a nickel-copper based alloy, such as monel 400, a nickel-chromium based alloy, such as inconel 625, other Co—Cr alloys, platinum enriched stainless steel; or the like; or other suitable material.
Within the family of commercially available nickel-titanium or nitinol alloys, is a category designated “linear elastic” which, although it may be similar in chemistry to conventional shape memory and superelastic varieties, exhibits distinct and useful mechanical properties. By the applications of cold work, directional stress, and heat treatment, the material is fabricated in such a way that it does not display a substantial “superelastic plateau” or “flag region” in its stress/strain curve. Instead, as recoverable strain increases, the stress continues to increase in a generally linear relationship (as compared to that of super-elastic material, which has a super-elastic plateau) until plastic deformation begins. In some embodiments, the linear elastic nickel-titanium alloy is an alloy that does not show any substantial martensite/austenite phase changes that are detectable by DSC and DMTA analysis over a large temperature range.
For example, in some embodiments, there are no substantial martensite/austenite phase changes detectable by DSC and DMTA analysis in the range of about −60° C. to about 120° C. The mechanical bending properties of such material are therefore generally inert to the effect of temperature over this very broad range of temperature. In some particular embodiments, the mechanical properties of the alloy at ambient or room temperature are substantially the same as the mechanical properties at body temperature. In some embodiments, the use of the linear elastic nickel-titanium alloy allows the guidewire to exhibit superior “pushability” around tortuous anatomy. Accordingly, components of guidewire 10, such as core member 30 and/or tubular member 20, or others, may include or be made of linear elastic nickel-titanium alloy.
In some embodiments, the linear elastic nickel-titanium alloy is 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. Some examples of nickel titanium alloys are disclosed in U.S. Pat. Nos. 5,238,004 and 6,508,803, which are incorporated herein by reference. In some other embodiments, a superelastic alloy, for example superelastic Nitinol can be used to achieve desired properties.
In one example, both the tubular member 20 and the core member 30 may comprise a nickel titanium alloy. In some other example embodiments, one of the tubular member 20 or the core member 30 may comprise stainless steel, and the other of the tubular member 20 or the core member 30 may comprise a nickel titanium alloy. In yet another example embodiment, the core member 30 can have a proximal section comprising stainless steel and a distal section comprising a nickel titanium alloy, and the tubular member 20 can comprise a nickel titanium alloy. As can be appreciated, these specific configurations are given by way of example, and that a broad variety of different configurations may be used including any of the materials listed herein, or others.
In at least some embodiments, portions or all of core member 30, tubular member 20, coils 36 and 120, and/or shaping ribbon 38, or other components that are part of or used in the device, may 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 the user of device 10 in determining its location. 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, radiopaque marker bands and/or coils may be incorporated into the design of guidewire 10 to achieve the same result.
In some embodiments, a degree of MRI compatibility is imparted into device 10. For example, to enhance compatibility with Magnetic Resonance Imaging (MRI) machines, it may be desirable to make core member 30, tubular member 20, coils 36 and 120, and/or shaping ribbon 38, or other portions of the medical device 10, in a manner that would impart a degree of MRI compatibility. For example, core member 30 and/or tubular member 20, or portions thereof, may be made of a material that does not substantially distort the image and create substantial artifacts (artifacts are gaps in the image). Certain ferromagnetic materials, for example, may not be suitable because they may create artifacts in an MRI image. Core member 30, tubular member 20, coils 36 and 120, and/or shaping ribbon 38, 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, Elgiloy, MP35N, nitinol, and the like, and others.
Referring now to the tubular member 20 as in the embodiments shown in
In some embodiments, as shown in
In embodiments where the distal and proximal sections 22/24 are two discrete and/or separate components that are attached, the variances in the outer diameters can be provided by the use of different discrete tubular components having different outer diameters. In embodiments where the tubular member 20 is a one-piece or monolithic member, the variances in the outer diameters can be provided by grinding or otherwise working the tubular member 20 to provide the desired diameters.
The tubular member 20 can optionally include a plurality of cuts, apertures, and/or slots 52 defined therein. In some embodiments, at least some, if not all of the slots 52 are disposed at the same or a similar angle with respect to the longitudinal axis of the tubular member 20. As shown, the slots 52 can be disposed at an angle that is perpendicular, or substantially perpendicular, to the tubular member longitudinal axis of the tubular member 20. However, in other embodiments, a group of one or more slots 52 may be disposed at different angles relative to another group of one or more slots 52.
The slots 52 may be provided to enhance the flexibility of the tubular member 20 while still allowing for suitable torque transmission characteristics. The slots or apertures 52 may be formed such that one or more rings and/or turns interconnected by one or more beams are formed in the tubular member 20, and such rings and beams may include portions of the tubular member 20 that remain after the slots 52 are formed in the body of the tubular member 20. Such an interconnected ring structure may act to maintain a relatively high degree of tortional stiffness, while maintaining a desired level of lateral flexibility. In some embodiments, some adjacent slots 52 can be formed such that they include portions that overlap with each other about the circumference of the tube 20. In other embodiments, some adjacent slots 52 can be disposed such that they do not necessarily overlap with each other, but are disposed in a pattern that provides the desired degree of lateral flexibility.
Additionally, the slots 52 can be arranged along the length of, or about the circumference of, the tubular member 20 to achieve desired properties. For example, the slots 52 can be arranged in a symmetrical pattern, such as being disposed essentially equally on opposite sides about the circumference of the tubular member 20, or equally spaced along the length of the proximal section 24 of the tubular member 20, or can be arranged in an increasing or decreasing density pattern, or can be arranged in a non-symmetric or irregular pattern. Other characteristics, such as slot size, slot shape and/or slot angle with respect to the longitudinal axis of the tubular member 20, can also be varied along the length of the tubular member 20 in order to vary the flexibility or other properties. In other embodiments, moreover, it is contemplated that the tubular member proximal section 24, or the entire tubular member 20, may not include any such slots 52.
Any of the above mentioned slots can be formed in essentially any known way. For example, slots 52 can be formed by methods such as micro-machining, saw-cutting, laser cutting, grinding, milling, casting, molding, chemically etching or treating, or other known methods, and the like. In some such embodiments, the structure of the tubular member 20 is formed by cutting and/or removing portions of the tube to form slots 52. Some example embodiments of appropriate micromachining methods and other cutting methods, and structures for tubular members and medical devices including tubular members are disclosed in U.S. Pat. Publication Nos. US 2003/0069522; and US 2004/0181174-A2; and U.S. Pat. Nos. 6,766,720; and 6,579,246, the entire disclosures of which are herein incorporated by reference. Some example embodiments of etching processes are described in U.S. Pat. No. 5,106,455, the entire disclosure of which is herein incorporated by reference.
Forming the tubular member 20, or sections thereof, may include any one of a number of different techniques. For example, the tubular member 20, including the distal and proximal sections 22/24 and/or components, may be created by casting or forming methods, stamping methods, or the like, and may be shaped or otherwise worked, for example, by centerless grinding methods, into the desired shape and/or form. A centerless grinding technique may utilize an indexing system employing sensors (e.g., optical/reflective, magnetic) to avoid excessive grinding of the connection. In addition, the centerless grinding technique may utilize a CBN or diamond abrasive grinding wheel that is well shaped and dressed to avoid grabbing tubular member 20 during the grinding process. In some embodiments, tubular member 20 is centerless ground using a Royal Master HI-AC centerless grinder.
In the embodiment of
The coil 120 can be wrapped in a helical fashion by conventional winding techniques. The pitch of adjacent turns of coil 120 may be tightly wrapped so that each turn touches the succeeding turn or the pitch may be set such that coil 120 is wrapped in an open fashion. In some embodiments, the coil can have a pitch of up to about 0.04 inches, in some embodiments a pitch of up to about 0.02 inches, and in some embodiments, a pitch in the range of about 0.001 to about 0.004 inches. The pitch can be constant throughout the length of the coil 120, or can vary, depending upon the desired characteristics, for example flexibility. These changes in coil pitch can be achieved during the initial winding of the wire, or can be achieved by manipulating the coil after winding or after attachment to the guidewire. For example, in some embodiments, after winding of the coil 120, a larger pitch can be achieved on the distal portion of the coil 120 by simply pulling the coil. Additionally, in some embodiments, portions or all of the coil 120 can include coil windings that are pre-tensioned or pre-loaded during wrapping, such that each adjacent coil winding is biased against the other adjacent coil windings to form a tight wrap. Such preloading could be imparted over portions of, or over the entire length of the coil 120. The diameter of the coil 120 is preferably sized to fit around the core member 30, and to give the desired characteristics.
Referring now to core member 30, for example in each of the
In embodiments where different portions of core member 30 are made of different materials, the different portions can be connected using any suitable connecting techniques. For example, the different portions of core member 30 can be connected using welding (including laser welding), soldering, brazing, adhesive, or the like, or combinations thereof. Additionally, some embodiments can include one or more mechanical connectors or connector assemblies to connect the different portions of core member 30 that are made of different materials. The connector may include any structure generally suitable for connecting portions of a guidewire. One example of a suitable structure includes a structure such as a hypotube or a coiled wire which has an inside diameter sized appropriately to receive and connect to the ends of the proximal portion and the distal portion. Some other examples of suitable techniques and structures that can be used to interconnect different shaft sections are disclosed in U.S. patent application Ser. Nos. 09/972,276 (U.S. Pat. Publication No. 2003/0069520), 10/086,992 (U.S. Pat. Publication No. 2003/0069521, and 10/375,766 (U.S. Pat. Publication No. 2004/0167441), which are incorporated herein by reference.
Core member 30 can have a solid cross-section, for example a core wire, but in some embodiments, can have a hollow cross-section. In yet other embodiments, core member 30 can include a combination of areas having solid cross-sections and hollow cross sections. Moreover, core member 30, or portions thereof, can be made of rounded wire, flattened ribbon, or other such structures having various cross-sectional geometries. The cross-sectional geometries along the length of core member 30 can also be constant or can vary. For example,
In some embodiments, a sheath and/or coating, for example a lubricious, a hydrophilic, a protective, or other type of material may be applied over portions or all of the core member 30 and/or tubular member 20 or 120, or other portions of device 10. Some examples of suitable polymer sheath materials may include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, for example, DELRIN® available from DuPont), polyether block ester, polyurethane, 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), polycarbonates, ionomers, biocompatible polymers, other suitable materials, or mixtures, combinations, copolymers thereof, polymer/metal composites, and the like.
In some embodiments sheath material can be blended with a liquid crystal polymer (LCP). For example, the mixture can contain up to about 6% LCP. This has been found to enhance torqueability. By employing selection of materials and processing techniques, thermoplastic, solvent soluble, and thermosetting variants of these and other materials can be employed to achieve the desired results. Some examples of suitable coating materials may include silicone and the like, hydrophilic polymers such as high-density polyethylene (HDPE), polytetrafluoroethylene (PTFE), polyarylene oxides, polyvinylpyrolidones, polyvinylalcohols, hydroxy alkyl cellulosics, algins, saccharides, caprolactones, and the like, and mixtures and combinations thereof. Some coating polymers may be blended among themselves or with formulated amounts of water insoluble compounds (including some polymers) to yield coatings with suitable lubricity, bonding, and solubility. Some other examples of such coatings and materials and methods used to create such coatings can be found in U.S. Pat. Nos. 6,139,510 and 5,772,609, which are incorporated herein by reference. Some examples of coatings would be disposing a coating on the thread member(s) and/or all or a portion of the tubular member and/or all or a portion of the core member.
A coating and/or sheath may be formed, for example, by coating, extrusion, co-extrusion, interrupted layer co-extrusion (ILC), or fusing several segments end-to-end. The layer may have a uniform stiffness or a gradual reduction in stiffness from the proximal end to the distal end thereof. The gradual reduction in stiffness may be continuous as by ILC or may be stepped as by fusing together separate extruded tubular segments. The outer layer may be impregnated with a radiopaque filler material to facilitate radiographic visualization. Those skilled in the art will recognize that these materials can vary widely without deviating from the scope of the present invention.
The length of the guidewire 10 is typically dictated by the length and flexibility characteristics desired in the final medical device. For example, proximal section 12 may have a length in the range of about 20 to about 300 centimeters or more, the distal section 14 may have a length in the range of about 3 to about 50 centimeters or more, and the medical device 10 may have a total length in the range of about 25 to about 350 centimeters or more. It can be appreciated that alterations in the length of sections and/or of the guidewire 10 as a whole can be made without departing from the spirit of the invention.
It should also be understood that a broad variety of other structures and/or components may be used in the guidewire construction. Some examples of other structures that may be used in the guidewire 10 include one or more coil members, braids, shaping or safety structures, such as a shaping ribbon or wire, marker members, such as marker bands or coils, centering structures for centering the core wire within the tubular member, such as a centering ring, an extension system, for example, to effectively lengthen the guidewire for aiding in exchanging other devices, or the like, or other structures. Those of skill in the art and others will recognize that the materials, structure, and dimensions of the guidewire may be dictated primary by the desired characteristics and function of the final guidewire, and that any of a broad range of materials, structures, and dimensions can be used.
In a further embodiment, any of the tubular members described herein can also be incorporated into devices other than the guidewires that have been shown. As one example, any of the tubular members mentioned herein can be incorporated into a catheter shaft. In some cases, incorporating such tubular members into a catheter shaft can provide certain desirable characteristics, such as torque transmission and lateral flexibility, and the like. For example, a catheter shaft with a metallic tubular member filet welded to an inner tubular member may provide some for a good connection between the members, and may provide for a desirable transition in outer diameters.
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 invention. For example, although set forth with specific reference to guidewires in some of the example embodiments shown in the Figures and discussed above, the invention may relate to virtually any medical device including an elongate metallic tubular member filet welded to a core structure and/or member. Thus, while the Figures and descriptions above are directed toward a guidewire, in other applications, sizes in terms of diameter, width, and length may vary widely, depending upon the desired properties of a particular device. The scope of the invention is, of course, defined in the language in which the appended claims are expressed.