Patent Application
20090036832
The present invention pertains to intracorporal medical devices, for example, intravascular guidewires, catheters, stents, and the like as well as improved methods for manufacturing medical devices. More particularly, the invention relates to guidewires and methods for making and using guidewires.
A wide variety of intracorporeal medical devices have been developed for medical use, for example, intravascular use. Some of these devices include guidewires, catheters, stents, and the like. Of the known medical devices, each has certain advantages and disadvantages. There is an ongoing need to provide alternative medical devices as well as alternative methods for manufacturing medical devices.
The invention provides design, material, and manufacturing method alternatives for medical devices. An example medical device includes a core member and a tubular member disposed over a portion of the core member. In at least some embodiments, the core member may include an outer diameter region that has an outside diameter that is substantially the same as the inside diameter of the tubular member so that the core member can be attached to the tubular member. These and other embodiments may also include a coil that is coupled to the tubular member.
The above summary of some embodiments is not intended to describe each disclosed embodiment or every implementation of the present invention. The Figures, and Detailed Description, which follow, more particularly exemplify these embodiments.
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:
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.
Turning now to
The design of guidewire 10 as well as other guidewires disclosed herein incorporates structural modifications create convenient attachment points, for example, between core wire 22 and tubular member 18. For example,
In at least some embodiments, first outer diameter region 24 and third outer diameter region 28 are positioned on opposing sides of second outer diameter region 26. Accordingly, at least a region of first outer diameter region 24 and at least a region of third outer diameter region 28 are disposed within tubular member 18. Consequently, the entire length of second outer diameter region 26 is also disposed within tubular member 18. Moreover, the length of regions 24/26/28 may vary. In at least some embodiments, second outer diameter region 26 is generally shorter than either of or both of regions 24/28.
Because second outer diameter region 26 has an outside diameter that is essentially the same as the inner diameter of tubular member 18, a “point of contact” (denoted by reference number 29 in
In some embodiments, a shaping member 31 may be coupled to third outer diameter region 28 and extend distally therefrom to a tip member 44. Shaping member 31 may include, for example, a shapeable or otherwise elastic material that allows tip 19 to be bent into a desired shape. Any suitable material, however, may be utilized. Tip member 44 may comprise, for example, a solder ball or bead. In other embodiments, third outer diameter region 28 may taper. These embodiments may or may not including a shaping member 31. For example,
With the above discussion in mind, the methods for manufacturing guidewire 10 may include providing tubular member 18, providing core wire 22, and securing core wire 22 to tubular member 18. The securing step may include forming a frictional engagement or fit, laser welding, spot welding, mechanical bond, etc. The types of bonds contemplated are discussed in more detail below. Alternative embodiments of the securing step may include adding and/or utilizing another substance (such as the joining substance discussed below) to secure tubular member 18 and core wire 22.
In some embodiments, the outside diameter of region 26 is sufficiently close to the inside diameter of tubular member 18 such that a frictional engagement is created that secures the integrity of the bond between these structures at the point of contact 29. The frictional bond helps keep core wire 22 in contact with tubular member 18 so that torque can be efficiently transferred therebetween. In these as well as other embodiments, a laser, spot, or similar type of weld 30 may be added to secure the bond between core wire 22 and tubular member 18 and, therefore, increase the probability that torque and/or other forces can be efficiently transferred between core wire 22 and tubular member 18.
Core wire 22 may be made from any suitable material such as a metal, metal alloy, polymer, metal-polymer composite, and the like. Some examples of suitable metals and metal alloys include stainless steel, such as 304V, 304L, and 316LV stainless steel; mild steel; nickel-titanium alloy such as linear-elastic and/or super-elastic nitinol; other nickel alloys such as nickel-chromium-molybdenum alloys (e.g., UNS: N06625 such as INCONEL® 625, UNS: N06022 such as HASTELLOY® C-22®, UNS: N10276 such as HASTELLOY® C276®, other HASTELLOY® alloys, and the like), nickel-copper alloys (e.g., UNS: N04400 such as MONEL® 400, NICKELVAC® 400, NICORROS® 400, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such as MP35-N® and the like), nickel-molybdenum alloys (e.g., UNS: N10665 such as HASTELLOY® ALLOY B2®), other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten or tungsten alloys, and the like; cobalt-chromium alloys; cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like); platinum enriched stainless steel; combinations thereof; and the like; or any other suitable material.
As alluded to above, within the family of commercially available nickel-titanium or nitinol alloys, is a category designated “linear elastic” which, although is similar in chemistry to conventional shape memory and superelastic varieties, exhibits distinct and useful mechanical properties. By 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 substantially linear relationship until plastic deformation begins. In some embodiments, the linear elastic nickel-titanium alloy is an alloy that does not show any 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 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 embodiments, the mechanical properties of the alloy at ambient or room temperature are substantially the same as the mechanical properties at body temperature. In other words, across a broad temperature range, the material maintains its linear elastic characteristics and/or properties and has essentially no yield point. In some embodiments, the use of the linear elastic nickel-titanium alloy allows the medical device to exhibit superior “pushability” around tortuous anatomy. Accordingly, components of guidewire 10 such as core wire 22 or any other structure of guidewire 10 may include 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 a superelastic nitinol can be used to achieve desired properties.
In at least some embodiments, portions or all of core wire 22 may also be doped with, made of, or otherwise include a 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 guidewire 10 in determining its location. Some examples of radiopaque materials can include, but are not limited to, gold, platinum, molybdenum, palladium, tantalum, tungsten or tungsten alloy, plastic material loaded with a radiopaque filler, and the like.
In some embodiments, a degree of MRI compatibility is imparted into guidewire 10. For example, to enhance compatibility with Magnetic Resonance Imaging (MRI) machines, it may be desirable to make core wire 22 or other portions of the guidewire 10, in a manner that would impart a degree of MRI compatibility. For example, core wire 22 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 wire 22 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: R30003 such as ELGILOY®, PHYNOX®, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such as MP35-N® and the like), nitinol, and the like, and others.
Some examples of suitable polymers may include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, for example, DELRIN® available from DuPont), polyether block ester, polyurethane, 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.
Tubular member 18 may similarly be made of a generally metallic material such as those listed above. In at least some embodiments, tubular member 18 is made from a nickel-titanium alloy (e.g., super elastic and/or shape memory nitinol). Any other suitable material may be utilized including those listed herein.
In at least some embodiments, tubular member 18 includes a plurality of cuts, apertures, and/or slots 20 formed therein. Slots 20 can be formed by methods such as micro-machining, saw-cutting (e.g., using a diamond grit embedded semiconductor dicing blade), laser cutting, electron discharge machining, 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 18 is formed by cutting and/or removing portions of the tube to form slots 20. Some example embodiments of appropriate micromachining methods and other cutting methods, and structures for tubular members including slots 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. It should be noted that the methods for manufacturing guidewire 10 may include forming slots 20 in tubular member 18 using any of these or other manufacturing steps.
Various embodiments of arrangements and configurations of slots 20 are contemplated. In some embodiments, at least some, if not all of slots 20 are disposed at the same or a similar angle with respect to the longitudinal axis of the tubular member 18. As shown, slots 20 can be disposed at an angle that is perpendicular, or substantially perpendicular, and/or can be characterized as being disposed in a plane that is normal to the longitudinal axis of tubular member 18. However, in other embodiments, slots 20 can be disposed at an angle that is not perpendicular, and/or can be characterized as being disposed in a plane that is not normal to the longitudinal axis of tubular member 18. Additionally, a group of one or more slots 20 may be disposed at different angles relative to another group of one or more slots 20. The distribution and/or configuration of slots 20 can also include, to the extent applicable, any of those disclosed in U.S. Pat. Publication No. US 2004/0181174, the entire disclosure of which is herein incorporated by reference.
Slots 20 may be provided to enhance the flexibility of tubular member 18 while still allowing for suitable torque transmission characteristics. Slots 20 may be formed such that one or more rings and/or turns interconnected by one or more segments and/or beams are formed in tubular member 18, and such rings and beams may include portions of tubular member 18 that remain after slots 20 are formed in the body of tubular member 18. 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 20 can be formed such that they include portions that overlap with each other about the circumference of tubular member 18. In other embodiments, some adjacent slots 20 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, slots 20 can be arranged along the length of, or about the circumference of, tubular member 18 to achieve desired properties. For example, adjacent slots 20, or groups of slots 20, can be arranged in a symmetrical pattern, such as being disposed essentially equally on opposite sides about the circumference of tubular member 18, or can be rotated by an angle relative to each other about the axis of tubular member 18. Additionally, adjacent slots 20, or groups of slots 20, may be equally spaced along the length of tubular member 18, 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 tubular member 18, can also be varied along the length of tubular member 18 in order to vary the flexibility or other properties. In other embodiments, moreover, it is contemplated that the portions of the tubular member, such as a proximal section, or a distal section, or the entire tubular member 18, may not include any such slots 20.
As suggested above, slots 20 may be formed in groups of two, three, four, five, or more slots 20, which may be located at substantially the same location along the axis of tubular member 18. Within the groups of slots 20, there may be included slots 20 that are equal in size (i.e., span the same circumferential distance around tubular member 18). In some of these as well as other embodiments, at least some slots 20 in a group are unequal in size (i.e., span a different circumferential distance around tubular member 18). Longitudinally adjacent groups of slots 20 may have the same or different configurations. For example, some embodiments of tubular member 18 include slots 20 that are equal in size in a first group and then unequally sized in an adjacent group. It can be appreciated that in groups that have two slots 20 that are equal in size, the beams (i.e., the portion of tubular member 18 remaining after slots 20 are formed therein) are aligned with the center of tubular member 18. Conversely, in groups that have two slots 20 that are unequal in size, the beams are offset from the center of tubular member 18. Some embodiments of tubular member 18 include only slots 20 that are aligned with the center of tubular member 18, only slots 20 that are offset from the center of tubular member 18, or slots 20 that are aligned with the center of tubular member 18 in a first group and offset from the center of tubular member 18 in another group. The amount of offset may vary depending on the depth (or length) of slots 20 and can include essentially any suitable distance.
While weld 30, as shown in
For a number of reasons, a number of guidewires such as guidewires 10/110 may include one or more coils. In some embodiments, the coils may be useful in forming the distal tip (e.g., a distal spring tip) of the guidewire. In these and other embodiments, the coils (i.e., one or more of the coils) may also desirably impact the overall design of the guidewire. For example, the coil or coils may be made from or otherwise include a radiopaque material, an MRI compatible and/or visible material, or any other suitable material including any of those disclosed herein that may desirably impact the design of guidewire 10/110.
When designing a guidewire that includes a coil, it may be useful to consider how the coil is secured to other components of the guidewire. This might include material considerations and bond compatibility between the coil and other guidewire components. For example, the coil may be made from a material that is not easily welded to a guidewire component such as a tubular member (e.g., tubular member 18/118) that is made from a nickel-titanium alloy.
The design of guidewire 210 may be useful when one of the coils 234/236 has a lower bonding affinity for tubular member 218. For example, second coil 234 may be made from a material such as stainless steel that is not easily welded to a nickel-titanium alloy tubular member 218. First coil 236, however, may be made from a radiopaque material such as platinum, which has an increased bonding affinity for nickel-titanium alloy. Therefore, the combination of bonds 238/240 efficiently secures together first coil 236, second coil 234, and tubular member 218. The methods for manufacturing guidewire 210 may include bonding coils 234/236 with tubular member 218 in this manner.
Second coil 234 may extend distally so as to form or define a spring tip region 242 of guidewire 210, terminating with a solder ball distal tip 244. The methods for manufacturing guidewire 210 may include forming tip region 242 with coil 234 and adding distal tip 244. In some embodiments, first coil 236 may proximally terminate as shown in
It can be appreciated that several coil configurations and/or arrangements are contemplated besides what is shown in
Furthermore, other embodiments of guidewire 210 may alter the relative position of core wire 22 relative to tubular member 218. For example,
In some embodiments, coil 342 may actually be a proximal portion of first coil 236. According to this embodiment,
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. The inventions scope is, of course, defined in the language in which the appended claims are expressed.
