Medical device having a radiopaque coil

Abstract

The medical device (100) includes an elongate member having a proximal end (112), a distal end (114), and a body (116) extending from the proximal end to the distal end, a blunt tip (182) disposed at or coupled to the distal end of the elongate member, and a radiopaque coil (190) coupled to the elongate member, wherein the radiopaque coil is moldable and has shape-retaining properties, and the shape-retaining moldable radiopaque coil has a bending stiffness that is at least 10% of the bending stiffness of the medical device.

Description

[Technical Field]

[0001] The field of the present application relates to medical devices, and more particularly to guidewires and catheters. [Background technology]

[0002] Guidewires are used in the medical field to access passageways within a patient's body. In some cases, it is desirable for the guidewire to have good torque transmission properties, so that a torque motion applied at the proximal end of the guidewire about the longitudinal axis of the guidewire causes a corresponding twisting motion at the distal end of the guidewire.

[0003] It may also be desirable for the distal segment of the guidewire to maintain a particular curved shape during use, allowing the distal segment of the guidewire to access a particular passageway having a particular shape within the patient's body. If the distal segment of the guidewire cannot maintain its curved shape during use, it may not be able to access the desired passageway.

[0004] Additionally, it may be desirable for the guidewire to have a soft distal segment, which prevents the guidewire from injuring the patient and allows the guidewire to resiliently flex and bend as it is advanced through the patient's body through passageways of various shapes.

[0005] However, it is difficult for a guidewire to achieve all of the above desirable characteristics. While a guidewire can have a soft distal segment, such a guidewire may have poor shape retention and poor torque transmission at the distal segment. On the other hand, some guidewires have good shape retention and good torque transmission at the distal segment. However, such guidewires may have a stiff distal segment. Typically, a soft guidewire distal segment does not provide good torque transmission due to the softness of the material used to form the distal segment, making it difficult to simultaneously achieve the above desirable characteristics. Additionally, the material used to make a soft distal guidewire segment may not allow the distal guidewire segment to maintain its shape during use.

[0006] Furthermore, one or more of the above technical problems also apply to catheters. Summary of the Invention

[0007] The medical device includes an elongate member having a proximal end, a distal end, and a body extending from the proximal end to the distal end, a blunt tip disposed at or coupled to the distal end of the elongate member, and a radiopaque coil coupled to the elongate member, wherein the radiopaque coil is moldable and has shape-retaining properties, and the shape-retaining moldable radiopaque coil has a bending stiffness that is at least 10% of the bending stiffness of the medical device.

[0008] Optionally, the bending stiffness of the formable radiopaque coil is at least 20% of the bending stiffness of the medical device.

[0009] Optionally, the shape-retaining, formable, radiopaque coil is made from a material having a modulus of elasticity of at least 3E7 psi.

[0010] Optionally, the shape-retentive, formable radiopaque coil is made from molybdenum rhenium (MoRe) or other molybdenum alloy, or tungsten, tungsten rhenium (WRe) or other tungsten alloy.

[0011] Optionally, the radiopaque coil is configured to assist in shape retention of the medical device.

[0012] Optionally, the bending stiffness of the radiopaque coil is greater than the bending stiffness of a coil made from platinum or a platinum alloy having the same size and shape as the radiopaque coil.

[0013] Optionally, the radiopaque coil is heat treated to optimize the formability and shape retention properties of the radiopaque coil.

[0014] Optionally, the medical device is a guidewire.

[0015] Optionally, the elongate member is a shaft and the radiopaque coil surrounds at least a portion of the shaft. Optionally, the medical device further includes a sleeve disposed around the radiopaque coil.

[0016] Optionally, the shaft includes a flattened portion. Optionally, the shaft includes a tapered portion proximal to the flattened portion.

[0017] Optionally, the shaft includes an additional flat or cylindrical portion proximal to the tapered portion.

[0018] Optionally, the medical device is a catheter.

[0019] Optionally, the elongate member is a tubular member and the radiopaque coil is coupled to the tubular member.

[0020] Optionally, a radiopaque coil is disposed circumferentially around or distal to the tubular member.

[0021] Optionally, the blunt tip has a straight surface at the distal end of the elongate member.

[0022] The guidewire includes a shaft having a proximal end, a distal end, and a body extending from the proximal end to the distal end, a blunt tip coupled to the distal end of the shaft, and a radiopaque coil disposed around at least a portion of the shaft, the radiopaque coil being moldable and having shape-retaining properties, and the shape-retaining moldable radiopaque coil having a bending stiffness that is at least 10% of the bending stiffness of the guidewire.

[0023] The catheter includes a tubular member having a proximal end, a distal end, and a body extending from the proximal end to the distal end, and a radiopaque coil coupled to the tubular member, the radiopaque coil being moldable and having shape-retaining properties, the shape-retaining moldable radiopaque coil having a bending stiffness that is at least 10% of the bending stiffness of the catheter.

[0024] Other and further aspects and features will become apparent from reading the following detailed description. [Brief explanation of the drawings]

[0025] The drawings illustrate the design and utility of the embodiments, and like elements are commonly numbered. The drawings are not necessarily drawn to scale. To better understand how the above-mentioned and other advantages and objects are obtained, a more particular description of the embodiments illustrated in the accompanying drawings will be provided. The drawings are set forth merely as exemplary embodiments, and therefore should not be considered as limiting the scope of the claims.

[0026] [Figure 1] FIG. 1 shows a guidewire having a radiopaque coil. [Figure 2] FIG. 2 shows a variation of the guidewire of FIG. 1, and in particular shows a guidewire having a malleable structure. [Figure 3] FIG. 3 shows a variation of the guidewire of FIG. 1, and in particular shows a guidewire having a radiopaque coil implemented as part of the sleeve. [Figure 4] FIG. 4 shows a technique for securing a radiopaque coil to the shaft of a guidewire. [Figure 5] FIG. 5 shows a graph illustrating the stress-strain curves of different materials. [Figure 6] FIG. 6 shows the radiopacity properties of different materials. [Figure 7] FIG. 7 shows a catheter with a radiopaque coil. [Figure 8] FIG. 8 shows a variation of the catheter of FIG. [Figure 9] FIG. 9 shows another variation of the catheter of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0027] Various embodiments will now be described with reference to the drawings. Note that the drawings are not drawn to scale, and elements having similar structure or function are represented by the same reference numerals throughout the drawings. Note also that the drawings are intended only to facilitate the description of the embodiments. They are not intended as an exhaustive description of the invention, nor are they intended to limit the scope of the invention. Furthermore, the illustrated embodiments need not possess all aspects or advantages of the disclosure. An aspect or advantage described in connection with a particular embodiment is not necessarily limited to that embodiment, and may be implemented in any other embodiment, even if not so shown or explicitly described.

[0028] FIG. 1 illustrates a guidewire 100 according to some embodiments. The guidewire 100 includes a shaft 110 having a proximal end 112, a distal end 114, and a body 116 extending from the proximal end 112 to the distal end 114. The body 116 of the shaft 110 includes a distal segment 120 having multiple different cross-sections along its length. At least an outer portion 130 of the body 116 proximal to the distal segment 120 is made of a material having a shear modulus of at least 13,000 ksi. By way of non-limiting example, the material of the outer body portion 130 is a molybdenum-rhenium alloy or a tungsten-rhenium alloy.

[0029] In other embodiments, the outer portion 130 of the body 116 can be made of a material having a shear modulus that is less than 13,000 ksi, and in other implementations, the material of the outer portion 130 can be other than a molybdenum-rhenium alloy or a tungsten-rhenium alloy.

[0030] In the illustrated embodiment, the shaft 110 includes a proximal segment 300 made of a first material and a distal segment 120 made of a second material different from the first material. In some embodiments, the proximal segment 300 can be made of a molybdenum-rhenium alloy or a tungsten-rhenium alloy. In some embodiments, the distal segment 120 can be made of nitinol, stainless steel, or a cobalt-chromium alloy (e.g., MP35N alloy).

[0031] The proximal segment 300 can be attached to the distal segment 120 by adhesive, welding, a mechanical connector, or fusion bonding.

[0032] In other embodiments, the proximal segment 300 and the distal segment 120 can be made from the same material. In one aspect, the segment 300 and the distal segment 120 have a unitary construction and are made from the same material.

[0033] As shown, the distal segment 120 includes a first portion 301, a second portion 302, a third portion 304, a fourth portion 306, and a fifth portion 308. The fifth portion 308 has a smaller cross-sectional dimension than the cross-sectional dimension of the third portion 304, which transitions to the larger cross-sectional dimension of the third portion 304 through the fourth (intermediate) portion 306. Similarly, the third portion 304 has a smaller cross-sectional dimension than the cross-sectional dimension of the first portion 301, which transitions to the larger cross-sectional dimension of the first portion 301 through the second (intermediate) portion 302. This configuration is advantageous because it provides progressively softer sections in the proximal-to-distal direction. As a result, the distal segment 120 is softer than the remainder of the body 116, with the distal portion 308 providing the softest section and allowing for easier flexing and bending. In other embodiments, the distal segment 120 may include more or fewer sections than those described above. In further embodiments, the segment 120 may have the same cross-sectional size and / or shape along its entire length.

[0034] As shown, the inner portion 330 of the body 116 proximal to the segment 120 and the outer portion 300 of the body 116 proximal to the segment 120 are made from the same material (as shown by the hatched cross section). In one embodiment, the outer portion 300 and the inner portion 330 of the body 116 are made from the same raw material (e.g., molybdenum-rhenium alloy, tungsten-rhenium alloy, etc.) and are integrally constructed. In other embodiments, the outer portion 300 and the inner portion 330 may be made from different materials. In still further embodiments, the outer portion 300 and the inner portion 300 may be made from different respective materials.

[0035] In some implementations, the portion 308 of the segment 120 can be compressed to form an elongated cross-sectional shape. For example, in some aspects, the portion 308 can have a circular cross-sectional shape, and the portion 308 of the segment 120 can be compressed into a planar configuration having an elongated cross-sectional shape (e.g., substantially rectangular) or other non-circular cross-sectional shape. This feature is advantageous because it biases the portion 308 in a bending direction. The elongated cross-sectional shape is also advantageous because it allows the portion 308 of the segment 120 to have sufficient cross-sectional area to achieve the desired tensile strength while still being flexible enough to bend in a plane. Compression of the portion 308 can be achieved in some embodiments by compressing (e.g., pressing, rolling, etc.) the portion 308. In other embodiments, the portion 308 of the segment 120 may not be compressed and / or may have a non-elongated cross-sectional shape. For example, in other embodiments, the portion 308 of the segment 120 may have a circular cross-sectional shape, a square cross-sectional shape, etc.

[0036] In the illustrated embodiment, the guidewire 100 also includes a sleeve 180 disposed around the distal end 114 of the shaft 110. As shown, the sleeve 180 has or is coupled to a blunt tip 182. The distal end 114 of the shaft 110 is also coupled to a blunt tip 182. The sleeve 180 can be any tubular member and can be made from any material, such as a metal, a polymer, or the like. In some embodiments, the sleeve 180 can be made from nitinol. The sleeve 180 can have multiple slots and / or openings to increase the flexibility of the sleeve 180. By way of non-limiting example, the sleeve 180 can be obtained using a slotted hypotube, a coiled sleeve, a tungsten-loaded polymer sleeve, or a combination thereof.

[0037] In one specific embodiment, the proximal segment 300 is made of a molybdenum-rhenium alloy, and the distal segment 120 is made of nitinol. In another specific embodiment, the proximal segment 300 is made of a molybdenum-rhenium alloy, and the distal segment 120 is made of stainless steel or a cobalt-chromium alloy (e.g., MP35N alloy). In either embodiment, the distal segment 120 provides the guidewire 100 with kink resistance and a soft distal end, while the proximal segment 300 provides the desired pushability and torqueability. The distal segment 120 is moldable during use (e.g., with or without the aid of the malleable structure 230), providing the desired shape retention. Furthermore, due to its relatively high shear modulus, the molybdenum-rhenium alloy proximal segment 300 provides the desired torqueability. Furthermore, the axial stiffness of the molybdenum-rhenium alloy segment 300 provides the guidewire 100 with the desired pushability. In some cases, the proximal segment 300 and the distal segment 120 can be made from one or more materials having one or more respective moduli of elasticity to provide the device with a desired bending stiffness.

[0038] As shown in FIG. 1 , guidewire 100 also includes coil 190 disposed within sleeve 180. As shown, one end of coil 190 is coupled to tip 182 (e.g., directly or indirectly secured to and extending from the tip). In other embodiments, the proximal end of coil 190 is coupled to distal segment 120 (e.g., directly or indirectly secured to and extending from the distal segment) (e.g., at any location proximal to portion 308, such as portion 306, portion 304, or portion 302). Securing can be achieved using adhesives, welding, mechanical connectors, fusion, or the like. In other embodiments, coil 190 can also be coupled to the wall of sleeve 180. In further embodiments, sleeve 180 can be at least partially formed by coil 190 ( FIG. 3 ). In that case, coil 190 has a cross-sectional dimension corresponding to (e.g., the same as) the cross-sectional dimension of sleeve 180. In other embodiments, coil 190 can form the entire sleeve 180.

[0039] In the illustrated embodiment, coil 190 is made from molybdenum rhenium (MoRe), which allows coil 190 to function as a radiopaque coil during a medical procedure. Additionally, coil 190 made from MoRe provides desirable stiffness and shape-retention characteristics to coil 190. The shape-retention characteristics of coil 190 help the distal portion of guidewire 100 maintain its bent shape after the distal portion of guidewire 100 is bent during a medical procedure.

[0040] In some cases, the wire comprising coil 190 can have a cross-sectional dimension (e.g., diameter) in the range of 0.001 inch to 0.005 inch. The wire comprising coil 190 can also have a length (unwound length) in the range of 5 cm to 150 cm. In other embodiments, the wire comprising coil 190 can have a cross-sectional dimension smaller than 0.001 inch or larger than 0.005 inch, and / or an unwound length greater than 20 cm.

[0041] In some cases, coil 190 can have a length in the range of 1 cm to 10 cm, and an outer diameter in the range of 0.004 inches to 0.05 inches, more preferably in the range of 0.006 inches to 0.02 inches, and even more preferably in the range of 0.008 inches to 0.01 inches.

[0042] In some cases, the loops of coil 190 may touch each adjacent (adjacent) loop. In other cases, coil 190 may have an open pitch, and the spacing between adjacent loops of coil 190 may be in the range of 0.0001 inches to 0.002 inches, or greater.

[0043] It should be noted that the coil 190 is advantageous because it has better shape retention than a cylindrical or flat solid section. This is due to the Bauschinger effect, which means that as the coil 190 is formed, strain occurs primarily in the shear direction and is uniformly distributed along the entire length of the wire forming the coil 190. The Bauschinger effect is more pronounced with higher levels of cold work. Because the coil 190 experiences relatively little cold work during forming (compared to, for example, a stamped tip), the coil 190 has better shape retention. Also, in some cases, the stiffness of the coil 190 can be a smaller percentage of the overall stiffness of the distal tip. This allows the coil 190 to form well and not significantly affect system behavior. In some cases, better tip shape retention (TSR) can be achieved by making the coil 190 stiffer and the other components of the guidewire 100 softer. MoRe has a shear modulus at least twice that of Pt alloys.

[0044] The stiffness (e.g., bending stiffness) of coil 190 can be adjusted by incorporating different amounts of rhenium (Re) in the MoRe alloy. As non-limiting examples, the MoRe alloy can have 47 wt%, 47.5 wt%, 41 wt%, or 25 wt% rhenium. In some cases, the amount of rhenium in the MoRe alloy is at least 15 wt%, preferably at least 20 wt%, and more preferably at least 30 wt% (e.g., in the range of 30 wt% to 60 wt%).

[0045] One approach to fabricating the coil 190 is to wind a wire or elongated element made of MoRe (or any of the other desirable materials described herein) around a mandrel. The cross-sectional shape of the elongated element (e.g., wire) comprising the coil 190 can be circular, rectangular, oval, or any other shape, and the resulting coil 190 can be modified by removing or adding material after winding, or by axial stretching or compression. Another approach to fabricating the coil 190 is to create a coil cut (e.g., laser cut) from the wall of a tube made of MoRe or any of the other desirable materials described herein. Thus, as used herein, the term "coil" is not limited to wire wound into a coil form. Optionally, the coil 190 can be annealed after winding to mitigate cold work induced during winding. Optionally, the coil 190 can also be treated using one or more hardening techniques (e.g., wire drawing parameter setting, heat treatment, shot peening, etc.) to achieve the desired stiffness of the coil 190.

[0046] In the embodiment of FIG. 1 , the distal portion 308 of the segment 120 is malleable. Thus, the distal portion 308 of the segment 120 can be bent to form a curved shape. The distal portion 308 is made of a material that allows the distal portion 308 of the segment 120 to retain its curved shape after being bent. In such a case, the coil 190 is also malleable and bendable, allowing the coil 190 and the distal portion 308 of the segment 120 to be bent together. The coil 190 also retains its bent shape, and thus, both the distal portion 308 of the segment 120 and the coil 190 together can retain the curved shape of the guidewire 100. In some embodiments, the distal portion 308 of the segment 120 alone does not provide sufficient bending stiffness. In such cases, the coil 190 can provide additional bending stiffness. It is desirable for the coil 190 to provide a significant portion of the overall bending stiffness (e.g., at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, or more) so that its shape retention contributes significantly to the system. The stiffness of the coil 190 can be adjusted by varying the coil pitch, coil wire diameter, coil wire modulus, material composition, or any combination thereof. Note that achieving the desired bending stiffness of the coil 190 is not easy because the wire of the coil 190 undergoes twisting when the coil 190 is bent. By utilizing the materials and techniques described herein to manufacture the coil 190, the desired bending stiffness of the coil 190 can be achieved.

[0047] In other embodiments, distal portion 308 may be made from a material that does not have sufficient shape-retention capabilities. In such cases, coil 190 provides the shape-retention properties of guidewire 100. That is, coil 190 either (1) assists distal portion 308 in providing the shape-retention properties of guidewire 100, or (2) provides at least a majority (e.g., all) of the shape-retention properties of guidewire 100.

[0048] In further embodiments, both distal portion 308 and coil 190 together may not provide sufficient shape retention for guidewire 100. In such cases, guidewire 100 may further include a malleable structure 230 (e.g., a flat plate, wire, shaped ribbon, etc.) attached to blunt tip 182 (FIG. 2). Malleable structure 230 may be disposed within sleeve 180. During use, malleable structure 230 is bendable to form a curved shape and is configured to retain the curved shape after malleable structure 230 is bent.

[0049] It should be noted that guidewire 100 is not limited to the examples shown in Figures 1 and 2, and that in other embodiments, guidewire 100 can have other configurations. In other embodiments, guidewire 100 can include more than one segment. For example, in other embodiments, guidewire 100 can include three or more segments connected in series along the longitudinal axis of guidewire 100. Also, in some embodiments, at least one of the segments of guidewire 100 can have multiple layers or a single layer.

[0050] Guidewire 100 is advantageous because it provides an optimal combination of formability, shape retention, and torque transmission. By using MoRe to construct coil 190, the resulting guidewire 100 can have a small profile. This allows guidewire 100 to be used to access smaller blood vessels, such as distal vessels in the brain, and to reach more aneurysms that were previously inaccessible. Coil 190 made from MoRe allows the distal portion of guidewire 100 to be formable during use, providing desirable shape retention (without the aid of a malleable structure). However, in other embodiments, guidewire 100 can optionally further include a malleable structure to enhance shape retention, as described above. Additionally, the distal portion of guidewire 100 provides guidewire 100 with desirable torque transmission, kink resistance, and a soft distal end.

[0051] The material for making the coil 190 is not limited to MoRe; in other cases, the coil 190 can be made from other materials. For example, in other cases, the coil 190 can be made from a combination of MoRe and one or more other alloying elements, such as Zr and / or Hf. In yet other cases, the coil 190 can be made from a combination of tungsten rhenium or tungsten and one or more other alloying elements, such as Zr and / or Hf. Any of these materials can enable the radiopaque coil 190 to achieve the desired bending stiffness. In other cases, materials other than the above examples can also be used to manufacture the coil 190.

[0052] In some cases, the modulus of elasticity of the material that enables radiopaque coil 190 to achieve the desired bending stiffness is at least 3E7 psi, preferably 4E7 or greater. The desired bending stiffness of coil 190 is at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, or more of the bending stiffness of guidewire 100.

[0053] Furthermore, in some cases, the material of coil 190 may exhibit X-ray attenuation equal to or greater than that of Pd (having a thickness equivalent to that of the material) at X-ray energy levels suitable for imaging. m is the X-ray attenuation A exhibited by Pd pd If the voltage does not change by more than 20% from 0.8A pd ≦A m ≦1.2A pd ), the x-ray attenuation exhibited by the material of coil 190 can be considered "comparable" to the attenuation of an equal thickness of Pd.

[0054] It should also be noted that the materials for fabricating the shaft 110 of the guidewire 100 should not be limited to the examples described above, and that in other embodiments, the shaft 110 can be fabricated from other materials. For example, in other embodiments, the shaft 110 of the guidewire 100 can be fabricated from other materials as long as the desired torque transmission characteristics are achieved. In other embodiments, the shaft 110 can be fabricated from any material having a Young's modulus (in the annealed condition) of at least 6,000 ksi, more preferably at least 30,000 ksi, and even more preferably at least 40,000 ksi. Also, in other embodiments, the shaft 110 can be fabricated from any material having an ultimate tensile strength of at least 100 ksi, more preferably at least 200 ksi, and even more preferably at least 300 ksi. By way of non-limiting example, specific materials that can be used include, but are not limited to, Mo-47.5Re, W-25Re, SS304, and the like.

[0055] In some cases, MoRe can have a tensile strength of approximately 1 kpsi, which is acceptable for use in constructing the shaft 110 of the guidewire 100. However, for the coil 190, it may be desirable to utilize a version of MoRe or another material with a lower tensile strength (and therefore a lower yield strength) to achieve formability. In some cases, the ultimate tensile strength (UTS) is in the range of 200-400 kpsi. In some cases, the UTS and yield strength of the coil 190 can be reduced by reducing the cold work during wire drawing. Subsequent heat treatment (annealing) can also be used to reduce the UTS of the coil 190.

[0056] It should be further noted that the shaft 110 of the guidewire 100 may have different dimensions in different embodiments. For example, in some embodiments, the shaft 110 of the guidewire 100 may have any overall length within a range of 50 inches to 100 inches, e.g., any length within a range of 70 inches to 90 inches. Also, in some embodiments, the distal segment 120 may have a length within a range of 5 inches to 30 inches, e.g., a length within a range of 10 inches to 25 inches, or a length within a range of 12 inches to 20 inches. Furthermore, in some embodiments, the distal portion 308 may have any length within a range of 0.3 inches to 1 inch, e.g., a length within a range of 0.5 inches to 0.8 inches. In some embodiments in which the distal portion 308 is pressed, the pressed distal portion may include a portion having a constant width, and the portion may have a longitudinal length of at least 0.3 inches, e.g., at least 0.4 inches. Additionally, in some embodiments, the distal segment 120 can have a cross-sectional dimension (e.g., diameter) in the range of 0.00157 inches to 0.0197 inches (0.04 mm to 0.5 mm), and the distal portion 308 can have a cross-sectional dimension (e.g., diameter) in the range of 0.000157 inches to 0.00394 inches (0.004 mm to 0.1 mm). In other embodiments, the distal segment 120 and / or the distal portion 308 can have different dimensions.

[0057] Furthermore, the number of different cross sections along the length of the distal segment 120 is not limited to the examples provided above. In other embodiments, the number of different cross sections along the length of the distal segment 120 may be greater or less than those described herein.

[0058] Additionally, in one or more embodiments described herein, a portion of segment 120 can have a flattened portion, as described above. For example, portion 308 (in the embodiment of FIG. 1 or FIG. 2) can be compressed (e.g., pressed, rolled, etc.) to form the flattened portion. In some embodiments, the flattened portion of segment 120 can include one or more openings that extend through the thickness of the flattened portion. This feature is advantageous because it helps guidewire 100 achieve a soft distal end without compromising other performance characteristics of guidewire 100, such as its formability, tensile strength, and / or shape retention.

[0059] Furthermore, it should be noted that the method of securing coil 190 to shaft 110 is not limited to the above-described example. In other embodiments, coil 190 can be secured to shaft 110 by other methods. For example, as shown in FIG. 4 , in some embodiments, coil 190 of guidewire 100 can be a radiopaque coil 190 that surrounds at least a portion of segment 120 of shaft 110 of guidewire 100. That portion of segment 120 has oppositely facing sides 800, 802, along each of which a recess 810 is provided for threading radiopaque coil 190 to that portion of segment 120. In some embodiments, the portion of segment 120 surrounded by radiopaque coil 190 can be a flat portion. In such a case, recess 810 can be a groove that penetrates the flat portion in the thickness direction. In some embodiments, recess 810 can be implemented as a notch. In other embodiments, the portion of segment 120 surrounded by coil 190 may be a different portion of segment 120 proximal to flattened portion 308. In further embodiments, the segment 120 surrounded by radiopaque coil 190 need not be a flattened portion. Instead, the segment 120 surrounded by radiopaque coil 190 may be a non-flattened portion of the core wire or shaft. The technique shown in FIG. 4 for attaching coil 190 to segment 120 is advantageous because it provides mechanical interaction between segment 120 and coil 190 and also saves space within the outer distal sleeve of guidewire 100. It is also advantageous because bond strength is achieved by a mechanical interface between segment 120 and coil 190, rather than an adhesive interface. In some cases, segment 120 can be manufactured by laser profiling a pressed member onto which coil 190 can be threaded.

[0060] In any of the embodiments described herein, guidewire 100 can be provided as part of a medical device. For example, the medical device can include a catheter and guidewire 100, where the catheter includes a lumen for receiving guidewire 100. By way of non-limiting example, the medical device can be a microcatheter, a balloon catheter, a stent delivery catheter, a catheter for removing an obstruction in a blood vessel, a delivery catheter for guidewire 100, etc.

[0061] In one method of using the guidewire 100, a physician first bends the distal segment of the guidewire 100 into a desired shape depending on the shape of the anatomical structure to be accessed by the guidewire 100. For example, the distal segment of the guidewire 100 can be bent into an L-shape, a C-shape, a U-shape, an S-shape, a shape with two or more curves in different planes, or the like. The guidewire 100 is then placed into a delivery catheter. An incision is then made in the patient's skin. The delivery catheter with the guidewire 100 inserted therein is then inserted through the incision into the patient's blood vessel. The delivery catheter and guidewire 100 can be advanced distally until the distal end of the guidewire 100 and / or delivery catheter reaches the target site. The target site can be anywhere in the patient's body, such as a vessel in the limbs, a vessel in the torso, a vessel in the neck, or a vessel in the head. The delivery catheter accommodates the guidewire 100 as the delivery catheter is advanced distally. When the delivery catheter reaches a location within the patient where the curved shape of the distal segment of the guidewire 100 is required for access, at least a portion of the distal segment can be deployed from the delivery catheter so that the distal segment assumes that curved shape. The guidewire 100 can be torqued to direct the curved shape in the direction of the desired access. The curved shape of the distal segment of the guidewire 100 guides the guidewire 100 in a desired direction, thereby allowing the guidewire 100 and delivery catheter to be advanced distally into a desired passageway. The guidewires 100 described herein are advantageous because they can retain the curved shape of the distal segment of the guidewire 100 and not return to their pre-bent configuration, even after the distal segment has passed through various paths within blood vessels with different curvatures (or even after the curved distal segment has been placed within a tube, such as a delivery tube). Guidewire 100 is also advantageous because the enhanced torque transmission of guidewire 100 allows a physician to effectively apply torque to guidewire 100, allowing the physician to push guidewire 100 distally within a patient's body without kinking.

[0062] Embodiments of guidewire 100 described herein have a desired torque transmission characteristic, a desired shape retention characteristic, a desired pushability characteristic, or any combination thereof. In some embodiments, guidewire 100 can be considered to have a desired torque transmission characteristic if a twisting or torque motion applied at the proximal end of guidewire 100 (or shaft 110) about the longitudinal axis of guidewire 100 to rotate the proximal end of guidewire 100 through an angle P results in rotation of the distal end of guidewire 100 through an angle D that is at least 80% of P, more preferably at least 90% of P, and even more preferably at least 95% of P (e.g., 100% of P, which means that the distal end of guidewire 100 has a 1:1 response to torque applied to the proximal end of guidewire 100). Additionally, in some embodiments, guidewire 100 may be considered to have the desired shape retention if a curved segment having a curvature can retain at least 70% of its curvature, more preferably at least 80% of its curvature, and even more preferably at least 90% of its curvature after the curved segment is placed in a tube and pushed back out of the tube. Additionally, in some embodiments, guidewire 100 may be considered to have the desired pushability if it does not kink while being advanced within a blood vessel.

[0063] It is advantageous to use MoRe to make the radiopaque coil 190. MoRe has a modulus of elasticity 2.5 to 3 times that of platinum or platinum alloys (see FIG. 5). In the figure, curve (a) is the stress-strain curve of a 25-um diameter round wire made from Mo41Re, curve (b) is the stress-strain curve of a 25-um diameter round wire made from W25Re, and curve (c) is the stress-strain curve of a 25-um diameter round wire made from Mo47Re. Guidewire 100 may require a small profile (e.g., diameter), which may limit the size of wire that can be used to make the radiopaque coil 190 for guidewire 100, limiting how stiff such coil 190 can be, and limiting how useful the coil 190 can be to help guidewire 100 maintain its distal curved shape. Using a stiffer MoRe material, or other materials described herein, to make a radiopaque coil improves the shape retention of the guidewire compared to conventional materials.

[0064] Also, in some embodiments, by appropriate selection of heat treatment parameters, the yield strain of the material (e.g., MoRe) of radiopaque coil 190 can be tailored so that coil 190 has a curvature that corresponds to the curvature of the core (e.g., shaft 110) during the forming process. Alternatively or additionally, the material of radiopaque coil 190 can be tailored to improve (e.g., optimize) the formability and / or shape retention characteristics of coil 190 (or guidewire / catheter). In some cases, heat treating the coil after winding can help eliminate cold work hardening that may occur during coil winding.

[0065] Additionally, fabricating the coil 190 using MoRe or other materials described herein can advantageously provide better shape retention than similarly shaped core wire ribbons by reducing the effects of the Bauschinger effect. The Bauschinger effect is the tendency of a plastically deformed metal to plastically deform in a direction opposite to the original deformation at lower stress levels. The extent of this effect is proportional to the degree of initial plastic deformation. To achieve the same total curvature in a coil versus a core wire ribbon, the effects of the Bauschinger effect should be reduced in a coiled configuration because the deformation (twist) of the coil is spread over a longer length of the coil wire.

[0066] Additionally, using the materials described herein (e.g., MoRe) to fabricate coil 190 is advantageous because it provides sufficient radiopacity for applications in medical procedures. The attenuation of an alloy is the sum of the individual coefficients of the elements, each multiplied by the weight fraction present in the alloy. As shown in Figure 6, in the relevant x-ray energy range, the attenuation of MoRe is close to that of Pt and Au, and slightly better than that of Pd and Ta, which are sometimes used for radiopaque elements.

[0067] Coils made from the materials described herein (e.g., MoRe, WRe, etc.) are not limited to guidewire applications, but may also be applied to other types of medical devices. In other embodiments, coils formed from MoRe, WRe, etc. may be part of a push wire or delivery wire. In further embodiments, coils made from MoRe, WRe, etc. may be part of a catheter, such as a delivery catheter, diagnostic catheter, therapeutic catheter, balloon catheter, etc.

[0068] 7 shows a catheter 700 having a coil 702 made from MoRe, WRe, or another material described herein. The catheter 700 may be a delivery catheter configured to deliver items such as drugs, medicines, medications, implants (e.g., vascular occlusion devices, stents, etc.), biopsy devices, therapeutic devices, etc. In other embodiments, the catheter 700 may be a delivery catheter configured to obtain a biopsy or tissue sample from a patient and deliver it to a container outside the patient's body. In some embodiments, the catheter 700 may further include an optionally inflatable balloon.

[0069] As shown, catheter 700 includes a tubular member 710 having a proximal end 712, a distal end 714, and a body 716 extending from proximal end 712 to distal end 714. Coil 702 is a radiopaque coil made from MoRe, WRe, or other materials described herein and is coupled to tubular member 710. Radiopaque coil 702 has a higher stiffness than a coil made from platinum or a platinum alloy having the same size and shape as the radiopaque coil. Additionally, at least a portion of radiopaque coil 702 is configured with a curvature that corresponds to the curvature of a portion of body 716 of tubular member 710.

[0070] In some embodiments, the radiopaque coil 702 is optionally moldable and has shape-retaining properties.

[0071] In the above embodiment, the coil 702 is disposed within the wall of the tubular member 710. In other embodiments, the coil 702 can be disposed on the exterior of the tubular member 710, surrounding the tubular member 710 (FIG. 8). In further embodiments, the coil 702 can be disposed distal to the tubular member 710 (FIG. 9). In such cases, the coil 702 can be secured to the tubular member 710 by adhesive and / or by a sleeve that engages both the coil 702 and the tubular member 710. The sleeve can be disposed on the interior surface of the tubular member 710 and the interior surface of the coil 702. Alternatively, the sleeve can be disposed on the exterior surface of the tubular member 710 and the exterior surface of the coil 702. In further embodiments, at least a portion of the tubular member 710 and at least a portion of the coil 702 can be disposed within the sleeve.

[0072] The following items are exemplary features of the embodiments described herein. Each item may be an embodiment by itself or may be part of an embodiment. One or more items described below may be combined with one or more other items in an embodiment.

[0073] Item 1: A medical device includes an elongate member having a proximal end, a distal end, and a body extending from the proximal end to the distal end, a blunt tip disposed at or coupled to the distal end of the elongate member, and a radiopaque coil coupled to the elongate member, wherein the radiopaque coil is moldable and has shape-retaining properties, and the shape-retaining moldable radiopaque coil has a bending stiffness that is at least 10% of the bending stiffness of the medical device.

[0074] Item 2: The bending stiffness of the formable radiopaque coil is at least 20% of the bending stiffness of the medical device.

[0075] Item 3: The shape-retaining, formable, radiopaque coil is made from a material having a modulus of elasticity of at least 3E7 psi.

[0076] Item 4: A moldable radiopaque coil with shape-retentive properties is made from molybdenum rhenium (MoRe) or other molybdenum alloys.

[0077] Item 5: A formable radiopaque coil with shape-retaining properties is made from tungsten, tungsten rhenium (WRe) or other tungsten alloys.

[0078] Item 6: The radiopaque coil is configured to assist in shape retention of the medical device.

[0079] Item 7: The bending stiffness of a radiopaque coil is greater than the bending stiffness of a coil made from platinum or a platinum alloy that has the same size and shape as the radiopaque coil.

[0080] Item 8: The radiopaque coil is heat treated to optimize the formability and shape retention properties of the radiopaque coil.

[0081] Item 9: The medical device is a guidewire.

[0082] Item 10: The elongate member is a shaft and the radiopaque coil surrounds at least a portion of the shaft.

[0083] Item 11: The medical device further includes a sleeve disposed around the radiopaque coil.

[0084] Item 12: The shaft includes a flat portion.

[0085] Item 13: The shaft includes a tapered portion proximal to the flattened portion.

[0086] Item 14: The shaft includes an additional flat or cylindrical section proximal to the tapered section.

[0087] Item 15: The medical device is a catheter.

[0088] Item 16: The elongate member is a tubular member and the radiopaque coil is coupled to the tubular member.

[0089] Item 17: The radiopaque coil is circumferentially disposed around or distal to the tubular member.

[0090] Item 18: The blunt tip has a straight surface at the distal end of the elongate member.

[0091] Item 19: A guidewire includes a shaft having a proximal end, a distal end, and a body extending from the proximal end to the distal end, a blunt tip coupled to the distal end of the shaft, and a radiopaque coil disposed around at least a portion of the shaft, wherein the radiopaque coil is moldable and has shape-retaining properties, and the shape-retaining moldable radiopaque coil has a bending stiffness that is at least 10% of the bending stiffness of the guidewire.

[0092] Item 20: A catheter comprising a tubular member having a proximal end, a distal end, and a body extending from the proximal end to the distal end, and a radiopaque coil coupled to the tubular member, wherein the radiopaque coil is moldable and has shape-retaining properties, and the shape-retaining moldable radiopaque coil has a bending stiffness that is at least 10% of the bending stiffness of the catheter.

[0093] While particular embodiments have been disclosed and described, it should be understood that this is not intended to limit the invention to the preferred embodiments. It will also be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. The invention is intended to cover alternatives, modifications, and equivalents.

Claims

1. It is a medical device, An elongated member having a proximal end, a distal end, and a body extending from the proximal end to the distal end, A blunt tip is positioned or attached to the distal end of the elongated member, The system comprises a radiopaque coil connected to the elongated member, A medical device characterized in that the radiopaque coil is moldable and provides shape-retaining properties that assist in maintaining the shape of the medical device.

2. A medical device according to Claim 1, characterized in that the bending stiffness of the moldable radiopaque coil is at least 10% of the bending stiffness of the medical device.

3. In the medical device described in claim 1, A medical device characterized in that a moldable, radiopaque coil having the shape-retaining properties is made from a material having an elastic modulus of at least 3E7psi.

4. In the medical device described in claim 1, A medical device characterized in that the moldable, radiopaque coil providing the shape-retaining properties is made from molybdenum rhenium (MoRe) or other molybdenum alloy.

5. In the medical device described in claim 1, A medical device characterized in that the moldable, radiopaque coil providing the shape-retaining properties is made from tungsten, tungsten rhenium (WRe), or other tungsten alloys.

6. In the medical device according to claim 1, A medical device characterized in that the bending stiffness of the radiopaque coil is greater than the bending stiffness of a coil made of platinum or a platinum alloy having the same size and shape as the radiopaque coil.

7. In the medical device described in Claim 1, A medical device characterized in that the radiopaque coil is heat-treated to optimize the molding performance and shape retention characteristics of the radiopaque coil.

8. In the medical device according to claim 1, A medical device characterized in that the medical device is a guide wire.

9. In the medical device according to claim 8, A medical device characterized in that the elongated member is a shaft, and the radiopaque coil surrounds at least a portion of the shaft.

10. In the medical device according to claim 8, A medical device further comprising a sleeve positioned around the radiopaque coil.

11. In the medical device according to claim 9, A medical device characterized in that the shaft includes a flat portion.

12. In the medical device according to claim 11, A medical device characterized in that the shaft further includes a tapered portion located proximal to the flat portion.

13. In the medical device according to claim 12, A medical device characterized in that the shaft includes an additional flat or cylindrical portion located proximal to the tapered portion.

14. In the medical device described in Claim 1, A medical device characterized in that the medical device is a catheter.

15. In the medical device according to claim 14, A medical device characterized in that the elongated member is a tubular member, the radiopaque coil is coupled to the tubular member, and the radiopaque coil is arranged circumferentially around the tubular member or distal to the tubular member.

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