Intravascular device

Abstract

To provide implantable medical devices.SOLUTION: An implantable medical device comprises an elongate member made of a material containing a platinum-tungsten alloy having a tungsten content of at least 10 wt.%. Alternatively, an implantable medical device comprises an elongate member made of a material containing a rhenium-containing alloy.SELECTED DRAWING: Figure 3-1

Description

Technical Field

[0001] The present disclosure generally relates to medical devices. More particularly, the present disclosure relates to medical devices such as intravascular implants.

Background Art

[0002] The use of intravascular medical devices has become an effective method for treating many types of vascular diseases. Intravascular medical devices such as stents, filters, thromboembolism capture devices, flow diverters, vascular occlusion devices, etc. are collectively referred to herein as "medical devices", but are often composed of various biocompatible materials such as polymers (e.g., non-biodegradable plastics and biodegradable plastics) and / or metals. Some of these medical devices are formed by one or more elongated members (e.g., wires, drawn-filled tubes, threads, filaments, etc.) woven into a braided or mesh pattern. Such braided devices can be utilized to treat various types of vascular defects such as aneurysms and can be provided in a wide variety of respective delivery and deployed sizes and shapes, particularly in a secondary shape when the device is placed at the target vascular system site. Some exemplary secondary shapes of braided devices include spheres, ovals, flat ribbons, helically braided ribbons, or combinations thereof that are suitable for treating vascular defects. Generally, a suitable intravascular implant device is inserted into a patient's vascular system and navigated through the vascular system to the target implantation site using known delivery systems and methods.

[0003] Medical devices can be made from shape memory or superelastic materials such as shape memory metals (e.g., shape memory nitinol) and polymers (e.g., polyurethane). Such shape memory plug devices can be induced (e.g., by temperature, electric field, magnetic field or light) to assume a predetermined shape (e.g., a radially expanded shape) after delivery to the treatment site. Superelastic materials, such as superelastic nitinol, assume a predetermined shape after delivery without the need for an inducing stimulus. Drug delivery medical devices can carry a bioactive or therapeutic agent (e.g., a thrombus inducer) and / or can coat the surface of the device.

[0004] The various physical attributes of a medical device can directly contribute to the success rate of the device. Those physical attributes include radiopacity, hoop strength, radial force, column strength, flexibility and dimensions of the materials used to form the device. Generally, cobalt-chromium (Co-Cr) and stainless steel are used to form stents. These materials are commonly used because they have a known history in terms of safety, effectiveness and biocompatibility. However, these materials have limited physical performance characteristics such as size, strength, weight, bendability, biostability and radiopacity.

[0005] Other commonly used materials include platinum, metal alloys of platinum and tungsten, and Elgiloy. Known medical devices made of platinum-tungsten alloy (Pt-W) are described and disclosed (by way of example) in U.S. Pat. Nos. 6,322,576, 6,458,119, 7,842,054, 9,198,670, 9,597,155, and U.S. Pub. No. 2007 / 0162108. However, these disclosures do not indicate the specific ratios of platinum and tungsten in the metal alloy, or explicitly disclose a preferred or desirable combination of an alloy having platinum (92%) and tungsten (8%) (i.e., Pt-8%wtW).

[0006] Due to higher elastic modulus and mechanical strength, some recent implantable devices including flow diversion stents are made from cobalt-chromium (Co-Cr) alloys designed to have appropriate radial forces. However, Co-Cr devices have undesirable properties such as very high magnetic susceptibility in magnetic resonance imaging (MRI), resulting in artifacts in MR images. Also, their radiopacity is poor. In known platinum-tungsten (Pt-W) alloys, up to 8% tungsten (W) is alloyed with platinum (Pt) to enhance mechanical strength, handleability, and manufacturability. Adding tungsten (W) to the platinum (Pt) matrix is generally thought to increase its brittleness and degrade the performance of the Pt-W alloy, so alloying with more than 8% tungsten (W) has generally not been considered. The commonly used Pt-8%wtW alloy has a relatively low magnetic susceptibility in MRI and higher radiopacity than Co-Cr, but the Pt-8%wtW alloy has a low elastic modulus and undesirably low radial expansion force, and thus has been found not to be suitable for such flow diversion stents. In particular, 8% tungsten (W) is added to the platinum (Pt) alloy to enhance mechanical strength, handleability, and manufacturability. However, adding more than 8% tungsten (W) is expected to increase the brittleness of the Pt-W alloy and has not been studied so far.

Summary of the Invention

[0007] Embodiments described herein are directed to implantable medical devices such as embolization devices and blood flow filters that are at least partially made (i.e., composed) from a platinum-tungsten alloy in which the proportion of tungsten in the alloy is about 10 wt% or more, for example, in the range of about 10 wt% to about 25 wt%, more preferably about 10 wt% to about 20 wt%.

[0008] In various embodiments, the implantable device is made from one or more elongated members made of a platinum-tungsten alloy, such as in the form of a cut tube, a coiled wire, or a plurality of wires woven in a braided configuration. The elongated member can include, but is not limited to, a composite wire having at least one layer made of a platinum-tungsten alloy. In other embodiments, the elongated member can include a composite wire having at least one layer made of an alloy containing rhenium.

[0009] In the technical field of manufacturing implantable medical devices, it has conventionally been believed that platinum-tungsten alloys having a tungsten ratio exceeding 8% are impossible to manufacture. However, through experiments, the inventors have discovered that platinum-tungsten alloys having a tungsten ratio of at least 10% by weight are not only manufacturable but also unexpectedly have several advantageous properties. As an example, such unexpected advantageous properties include having a substantially greater ultimate tensile strength, a substantially greater Young's modulus, and a substantially lower magnetic susceptibility than alternative materials of the same dimensions made of a platinum-tungsten alloy having a tungsten ratio of about 8% by weight, but are not limited thereto.

[0010] Using the materials disclosed herein, one or more elongated members of the implantable medical device can be fabricated to have a very small cross-section, such as a cross-sectional dimension of less than 0.0015 inches, for example, in the range of 0.0001 inches to 0.0015 inches, 0.0008 inches to 0.0013 inches, 0.0001 inches to 0.0008 inches, or 0.0003 inches to 0.00075 inches. In some embodiments, the cross-sectional dimension of the elongated member is less than 0.0013 inches, less than 0.001 inches, or even less than 0.00085 inches.

[0011] According to some embodiments, the implantable medical device includes an elongated member having a cross-sectional dimension of less than 0.00085 inches, and the elongated member is made of a material including a platinum-tungsten alloy having a tungsten ratio of at least 10 wt%.

[0012] Optionally, the implantable medical device has a longitudinal axis, and the length measured in the direction of this longitudinal axis is at least 1.2 inches or comparable to at least 0.4 inches. The implantable medical device can be inserted longitudinally into a tube having a lumen, and at least a part of the lumen has a diameter of 0.03 inches or less or 0.02 inches or less. The implantable medical device has sufficient column strength to allow the implantable medical device to be pushed through the lumen without undergoing buckling, kinking, or plastic deformation.

[0013] Optionally, the implantable medical device has a first radius of curvature R1 when in a relaxed configuration before insertion into the catheter, and a second radius of curvature R2 after the implantable medical device is inserted into the catheter and delivered from the catheter, and R2 is less than 5 times R1.

[0014] Optionally, the elongated member has a greater ultimate tensile strength, a greater Young's modulus, and a smaller magnetic susceptibility respectively than an alternative elongated member of the same dimensions made of an alternative platinum-tungsten alloy having a tungsten ratio of 8 wt%.

[0015] Optionally, the cross-sectional dimension of the elongated member is any value between 0.0001 inches and 0.0008 inches.

[0016] Optionally, the cross-sectional dimension of the elongated member is any value between 0.0003 inches and 0.00075 inches.

[0017] Optionally, the material has a Young's modulus of 30 Msi or more.

[0018] Optionally, the material has an ultimate tensile strength (UTS) of 350 ksi or more.

[0019] Optionally, the elongate member forms part of a braid.

[0020] Optionally, the implantable medical device further includes a first coil segment at a first end of the braid.

[0021] Optionally, the implantable medical device further includes a second coil segment at a second end of the braid.

[0022] Optionally, the first coil segment is made from a coil wire having a cross-sectional dimension between 0.0001 inches and 0.002 inches, and the first coil segment has a primary coil diameter between 0.003 inches and 0.030 inches.

[0023] Optionally, the braid has a number of wires between any of 8 to 96, between any of 16 to 32, between any of 24 to 144, or between any of 24 to 72.

[0024] Optionally, the braid includes a flat braid.

[0025] Optionally, the material also includes Ta, Ir, Re, Rh, Ru, Mo, Zr, Hf, Au, or any combination thereof.

[0026] Optionally, the elongate member is a draw-fill tube.

[0027] Optionally, the maximum lumen width of at least a portion of the catheter is less than 0.014 inches.

[0028] According to other embodiments, the implantable medical device includes an elongate member made from a material including an alloy containing rhenium.

[0029] Optionally, the elongated member has a cross-sectional dimension of less than 0.001 inch, more preferably less than 0.0085 inch.

[0030] Optionally, the elongated member has a cross-sectional dimension of any value between 0.0001 inch and 0.0008 inch.

[0031] Optionally, the elongated member has a cross-sectional dimension of any value between 0.0003 inch and 0.00075 inch.

[0032] Optionally, the alloy includes a molybdenum-rhenium alloy.

[0033] Optionally, the alloy includes a tungsten-rhenium alloy.

[0034] Optionally, the implantable medical device has a longitudinal axis, the length measured in the direction of this longitudinal axis is at least 1.2 inches, the implantable medical device can be inserted longitudinally into a tube having a lumen, at least a part of the lumen has a diameter of 0.02 inches or less, and the implantable medical device has a column strength sufficient to allow the implantable medical device to be pushed through the lumen without undergoing buckling, kinking or plastic deformation.

[0035] Optionally, the implantable medical device has a first radius of curvature R1 when in a relaxed configuration before insertion into the catheter and a second radius of curvature R2 after the implantable medical device is inserted into the catheter and delivered from the catheter, and R2 is less than 5 times R1.

[0036] Optionally, the elongated member has a greater ultimate tensile strength, a greater Young's modulus and a smaller magnetic susceptibility respectively than an alternative elongated member of the same dimensions made of an alternative platinum-tungsten alloy having a tungsten proportion of 8 wt%.

[0037] Optionally, the material has a Young's modulus of 30 Msi or more.

[0038] Optionally, the material has an ultimate tensile strength (UTS) of 350 ksi or more.

[0039] Optionally, the elongate member forms part of a braid.

[0040] Optionally, the implantable medical device further includes a first coil segment at a first end of the braid.

[0041] Optionally, the implantable medical device further includes a second coil segment at a second end of the braid.

[0042] Optionally, the first coil segment is made from a coil wire having a cross-sectional dimension between 0.0001 inches and 0.002 inches, and the first coil segment has a primary coil diameter between 0.003 inches and 0.030 inches.

[0043] Optionally, the braid has a number of wires between any of 8 to 96, between any of 16 to 32, between any of 24 to 144, or between any of 24 to 72.

[0044] Optionally, the braid includes a flat braid.

[0045] Optionally, the material also includes Ta, Ir, Rh, Ru, Mo, Zr, Hf, Au, or any combination thereof.

[0046] Optionally, the elongate member is a pull-fill tube.

[0047] The kit includes an implantable medical device and a catheter.

[0048] Optionally, the maximum lumen width of at least a portion of the catheter is less than 0.014 inches.

[0049] According to other embodiments, the implantable medical device includes an elongate member having a cross-sectional dimension of less than 0.00085 inches, the implantable medical device having a longitudinal axis, the length measured in the direction of the longitudinal axis being at least 1.2 inches, the implantable medical device being insertable longitudinally into a tube having a lumen, at least a portion of the lumen having a diameter of 0.02 inches or less, and the implantable medical device having sufficient column strength to allow the implantable medical device to be pushed through the lumen without undergoing buckling, kinking, or plastic deformation.

[0050] Other and further aspects and features of the embodiments will become apparent from the following detailed description with reference to the accompanying drawings.

Brief Description of the Drawings

[0051]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0052] For the following defined terms, these definitions shall apply unless otherwise defined in the claims or elsewhere in this specification.

[0053] In this specification, all numerical values shall be considered to be modified by the term "about", whether or not explicitly indicated. The term "about" generally refers to a range of numerical values that are considered equivalent (i.e., having the same function or result) to the value mentioned by those skilled in the art. In many cases, the term "about" may include numbers rounded to the nearest significant digit.

[0054] The description of a numerical range by endpoints includes all numerical values within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0055] As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally used in the sense of "and / or" unless the context clearly dictates otherwise.

[0056] Hereinafter, various embodiments of the disclosed invention will be described with reference to the drawings. The drawings are not necessarily drawn to scale, and the relative scales of selected elements may be exaggerated for clarity. Elements having the same structure or function are represented by the same reference numerals throughout the drawings. Also, the drawings are only intended to facilitate the description of the embodiments and are not intended to provide an exhaustive description of the disclosed invention or to limit the scope of the disclosed invention. It should be understood that the scope of the disclosed invention is defined only by the appended claims and their equivalents.

[0057] Furthermore, each of the exemplified embodiments of the disclosed invention need not have all of the described features, and the features, aspects, or advantages described in connection with a particular embodiment are not necessarily limited to that embodiment and may be implemented in other embodiments even if not so shown.

[0058] Metal alloy In various embodiments described herein, a metal alloy comprising platinum and tungsten (Pt-W) having a ratio of tungsten (W) of 10% or more of the alloy (i.e., hereinafter, mass% or weight%) is used in the manufacture of medical devices. In some embodiments, the ratio of tungsten (W) is in the range of 10% to 25% of the alloy, more preferably in the range of 10% to 20%. In those embodiments, most of the remaining proportion of the alloy consists of platinum (Pt). For example, when the ratio of tungsten (W) is 10% or more, the ratio of platinum (Pt) is 90% or less of the alloy, and when the ratio of tungsten (W) is 20% or more, the ratio of platinum (Pt) is 80% or less of the alloy.

[0059] In one or more embodiments described herein, the ratio of tungsten (W) is 10% or more of the platinum-tungsten (Pt-W) alloy used to form a medical device. By having a ratio of tungsten (W) of 10% or more of the platinum-tungsten (Pt-W) alloy forming the medical device, improved properties are provided as compared to known medical devices having 8% or less of tungsten (W) in the platinum-tungsten (Pt-W) alloy.

[0060] As described above, according to conventional common sense, it is not recommended to increase the ratio of tungsten in the platinum-tungsten alloy used to construct an implantable medical device. However, when the present inventors examined and studied the Pt-W phase diagram, nevertheless, they considered that Pt-high W-containing alloys are useful. The present inventors predicted from theoretical analysis that the mechanical strength of the resulting alloy may be improved. However, experiments using a Pt-16%W alloy showed very excellent unexpected results, including an improvement in mechanical properties, an increase in radiopacity (important for blood flow diverter devices), and most surprisingly, a significant decrease in magnetic susceptibility (which was expected to show little change).

[0061] Those unexpected properties of the disclosed platinum-tungsten (Pt-W) alloy include, for example, one or more of exemplary properties such as column strength, radial strength, hoop strength, tensile strength, tensile elongation, stress-strain properties, radial force, radiopacity, flexibility, bendability, thermal sensitivity, biocompatibility, etc. In particular, in a medical device where the proportion of tungsten (W) in the platinum-tungsten (Pt-W) alloy is 10% or more, the radiopacity, radial strength, hardness, yield strength and / or ultimate tensile strength of the device increase, and / or the stress-strain properties, compression and / or expansion properties, bendability and / or flexibility, overall strength and / or durability of the device, longitudinal elongation properties, resilience properties, coefficient of friction, thermal sensitivity properties, biostability and / or biocompatibility properties of the device are further improved, and / or it is possible to enable the manufacture of a smaller, thinner and / or lighter medical device. For example, a medical device having a proportion of tungsten (W) of 10% or more in the platinum-tungsten (Pt-W) alloy is configured to have a Young's modulus of 30 Ksi or more. Additionally or alternatively, a medical device having a proportion of tungsten (W) of 10% or more in the platinum-tungsten (Pt-W) alloy is configured to have a magnetic susceptibility in the range of 10 ppm to 300 ppm, thereby reducing artifacts during MR imaging.

[0062] For example, current flow diversion stents made of cobalt-chromium (Co-Cr) alloy have very high magnetic susceptibility in MRI (i.e., MR artifacts) and low radiopacity. For this reason, MR follow-up imaging is provided that is not suitable for implanted flow diversion stents made of Co-Cr. In some cases, to improve the radiopacity of Co-Cr flow diversion stents, Pt-8%W alloy wire is blended with Co-Cr wire. However, a flow diversion stent having a tungsten (W) proportion of 10% or more of a platinum-tungsten (Pt-W) alloy can achieve appropriate excellent radiopacity and radial force due to a high elastic modulus, for example, compared to a Co-Cr alloy. Further, a flow diversion stent having a tungsten (W) proportion of 10% or more of a platinum-tungsten (Pt-W) alloy has a very low magnetic susceptibility to MR artifacts and enables MR follow-up imaging of the implanted flow diversion stent.

[0063] These one or more improved properties of a medical device having a tungsten (W) proportion of 10% or more of a platinum-tungsten (Pt-W) alloy can be achieved without increasing the volume and / or weight of the device. Further, these improved properties are considered to be obtained when the volume and / or weight of the medical device is reduced compared to a device formed at least in part from known materials such as stainless steel, cobalt-chromium (Co-Cr), or a platinum-tungsten (Pt-W) alloy having 8% or less tungsten (W).

[0064] Furthermore, it should be understood that as long as the proportion of tungsten (W) is 10% or more of the platinum-tungsten (Pt-W) alloy, the proportion of platinum (Pt) in the alloy may be less than the range of 90% to 80% so that other materials can be present. In those embodiments, the platinum-tungsten (Pt-W) alloy can include other elements in a smaller proportion (e.g., 5% or less). For example, titanium (Ti) to reduce the radiopacity level, or zirconium (Zr), hafnium (Hf) and / or gold (Au) to obtain a desired level of magnetic susceptibility, or tantalum (Ta), iridium (Ir), rhenium (Re), rhodium (Rh), ruthenium (Ru) and / or molybdenum (Mo) to obtain a desired level of mechanical properties, any combination of these elements or any other suitable elements can be included.

[0065] Furthermore, a medical device constructed using the disclosed platinum-tungsten (Pt-W) alloy having a tungsten (W) proportion of 10% or more of the alloy can include one or more materials that impart desired properties to the device so as to withstand the manufacturing processes required to manufacture the device. These manufacturing processes include, for example, laser cutting, etching, crimping, annealing, stretching, pilger rolling, electroplating, electropolishing, chemical polishing, cleaning, pickling, ion beam evaporation or implantation, sputter coating, vacuum evaporation, etc.

[0066] As a non-limiting example, the disclosed platinum-tungsten (Pt-W) alloy is at least 95% of the medical device. Furthermore, the disclosed platinum-tungsten (Pt-W) alloy having a tungsten (W) proportion of 10% or more can be used to form devices such as stents (e.g., slotted tube stents and / or braided stents or woven stents), filters, thrombus capture devices, flow diverters, vascular occlusion devices, intrasac aneurysmal implants, vascular delivery assemblies, catheters, reinforcement members, guide wires, delivery wires, radiopaque markers, etc.

[0067] As a non-limiting example, the disclosed platinum-tungsten (Pt-W) alloy having a tungsten (W) proportion of 10% or more of the alloy can be configured to at least partially form a medical device. For example, the alloy may form a majority weight percentage of the medical device, but it may not be essential.

[0068] As an example, the embodiments of FIGS. 1A - 3F show an implantable medical device constructed using the disclosed platinum-tungsten (Pt-W) alloy having a tungsten (W) proportion of 10% or more of the alloy.

[0069] Figures 1A - 1C show exemplary braided plug devices in the form of a tubular braided stent and / or flow diverter 10 constructed in accordance with several embodiments. Figure 1A shows the braided stent 10 in a radially expanded delivery configuration having a proximal portion 12, a distal portion 14, and a lumen 16 extending therebetween. The braided stent 10 is formed from a plurality of elongated members 20 (e.g., wires, pull - through filling tubes, threads, filaments, etc.) braided together. Figure 1B is a two - dimensional plan view of a section of the wall 18 of the braided stent 10, showing that the elongated braided members 20 are woven in a standard repeating “one over, one under” pattern 50 (detailed in Figure 1A), which is a common weaving pattern used in known braided plug devices. One or more of the elongated members 20 are composed of a disclosed platinum - tungsten (Pt - W) alloy having a proportion of tungsten (W) of 10% or more. The elongated members 20 of Figures 1A and 1B can include a ribbon - like configuration having a generally rectangular cross - section (Figure 1C). As further shown in Figure 1C, the ribbon - like elongated member 20 has a width (W1) of 0.004 inches (0.102 mm) and a height (H1) of 0.002 inches (0.051 mm). In some embodiments, the ribbon - like elongated member 20 has a maximum width of 0.005 inches (0.127 mm) and a minimum height (thickness) of 0.0008 inches (0.0203 mm). In other embodiments, the ribbon - like elongated member 20 can have a maximum width of 0.002 inches (0.051 mm) and a minimum height of 0.0001 inches (0.00254 mm). In various embodiments, the ribbon - like elongated member 20 can have a cross - sectional dimension (width or thickness) in the range of 0.0001 inches to 0.0015 inches, e.g., less than 0.0013 inches, less than 0.001 inches, or even less than 0.00085 inches. In a further embodiment where the elongated member 20 has a generally circular cross - section (not shown), the diameter of the circular cross - section of the elongated member 20 is in the range of 0.0008 inches (0.0203 mm) to 0.004 inches (0.102 mm), preferably in the range of 0.001 inches (0.025 mm) to 0.002 inches (0.051 mm).In other embodiments, the diameter of the circular cross-section of the elongate member 20 may be less than 0.00085 inches, preferably between 0.0001 inches and 0.0008 inches, more preferably between 0.0003 inches and 0.00075 inches. It should be understood that the elongate member 20 can include other cross-sectional shapes. For example, in other embodiments, the elongate member 20 may be a braided wire having a diameter anywhere between 0.0001 inches (0.00254 mm) and 0.0015 inches (0.0381 mm), preferably anywhere between 0.0005 inches (0.0127 mm) and 0.001 inches (0.0254 mm).

[0070] In the embodiments of FIGS. 1A and 1B, the braiding pattern 50 or braiding specification of the stent 10 includes from 24 to 144 elongate members 20, preferably from 48 to 120 elongate members 20, or from 24 to 72 elongate members 20. Further, the radially expanded delivery configuration of the braided stent 10 has from 30 to 200, preferably from 50 to 150, PPI.

[0071] Returning to the disclosed platinum-tungsten (Pt-W) alloy having a proportion of tungsten (W) of 10% or more that forms one or more of the elongated members 20, a stent 10 having the following characteristics is provided. a) The stent 10 achieves a higher radial force due to a higher material elastic modulus and strength. b) The stent 10 is configured to be manufactured with a greater number of wires by smaller elongated members 20, thereby achieving a better flow diversion effect. c) The stent 10 is configured to reduce MR image artifacts for follow-up imaging procedures due to its low magnetic susceptibility, making the stent 10 more suitable for MR imaging and / or the stent 10 is configured to have complete radiopacity and the other advantages described above. Further, if the radiopacity of the stent 10 is too high for the application, the device can be manufactured using a combination of the elongated members 20 made of the disclosed platinum-tungsten (Pt-W) alloy and another material or alloy with low radiopacity, or a composite wire consisting of the disclosed platinum-tungsten (Pt-W) alloy as the outer layer and another alloy with low radiopacity as the core can be used to manufacture the device. The above-described characteristics of the stent 10 made of the disclosed platinum-tungsten (Pt-W) alloy having a proportion of tungsten (W) of 10% or more that forms one or more of the elongated members 20 are compared with stents made of cobalt-chromium (Co-Cr) alloy or other available materials.

[0072] In other embodiments, the braided stent 10 can be made from an alloy containing rhenium. For example, the braided stent 10 can be fabricated from a material containing a molybdenum-rhenium (Mo-Re) alloy or a tungsten-rhenium (W-Re) alloy. Also, in some embodiments, the material can be further alloyed with Ta, Ir, Rh, Ru, or any combination thereof to enhance the mechanical properties of the material. In further embodiments, the material can be further alloyed with Zr, Hf, Au, or any combination thereof to reduce the magnetic susceptibility.

[0073] Figures 2A and 2B show an exemplary in - sac device in the form of an embolization coil 100 constructed in accordance with some embodiments. The embolization coil 100 is another example of an implantable medical device. The coil 100 is formed from a helically wound wire 102 having a first end 104 and a second end 106. The coil 100 includes a stretch - resistant member 108 fixedly attached to both the first end 104 and the second end 106. In an alternative embodiment, the stretch - resistant member 108 may be attached to one of the two ends, or may not be attached to either of the two ends. The coil 100 in FIG. 2A is shown in a “primary” winding or shape, and the coil 100 in FIG. 2B is shown in a “secondary” winding or shape. The secondary shape of the coil 100 in FIG. 2B forms a substantially spherical three - dimensional shape having non - overlapping loops 120. It should be understood that the secondary shape of the coil 100 can take any other suitable shape. The wire 102 of the coil 100 can be formed of a single wire, a drawn - fill tube, a thread, a filament, etc. In some embodiments, as shown in FIGS. 2A and 2B, the diameter (D1) of the wire 102 ranges from about 0.0005 inches (0.0127 mm) to about 0.005 inches (0.127 mm), the primary coil diameter (D2) of the coil 100 ranges from about 0.003 inches (0.0762 mm) to about 0.030 inches (0.762 mm), and / or the secondary coil diameter (D3) ranges from about 0.5 mm to about 50 mm.

[0074] The wire 102 of the coil 100 (Figs. 2A and 2B) is composed of a disclosed platinum-tungsten (Pt-W) alloy having a tungsten (W) ratio of 10% or more. When the coil 100 is composed of the disclosed platinum-tungsten (Pt-W) alloy, the coil 100 has the following characteristics (e.g., compared with a coil composed of platinum (Pt-8W) having 8% tungsten). a) With a high elastic modulus that provides high column strength, the coil 100 is configured to support a longer length without a correspondingly large wire 102. b) With a high yield strength, the coil 100 is configured to be a more effective framing device. c) Due to the stability of the alloy, the coil is configured to achieve better shape retention and deliverability for coils treating small aneurysms (e.g., less than 2 mm due to a combination of higher strength and higher elastic modulus).

[0075] As described above, the coil 100 made of the disclosed platinum-tungsten (Pt-W) alloy having a tungsten (W) ratio of 10% or more of the wire has a low MR artifact due to its low magnetic susceptibility compared to the current coil made of the Pt-8%W alloy.

[0076] In other embodiments, the coil 100 can be made from an alloy containing rhenium. For example, the coil 100 can be made from a material containing a molybdenum-rhenium (Mo-Re) alloy or a tungsten-rhenium (W-Re) alloy. Also, in some embodiments, the material may be further alloyed with Ta, Ir, Rh, Ru, or any combination thereof to enhance the mechanical properties of the material. In further embodiments, the material may be further alloyed with Zr, Hf, Au, or any combination thereof to reduce the magnetic susceptibility.

[0077] Figures 3A - 3F illustrate an exemplary braided endovascular device 200 having a non - traumatic end member 270 constructed in accordance with several embodiments. The braided endovascular device 200 is another example of an implantable medical device. Figure 3A shows the braided endovascular device 200 in a radially expanded (i.e., unconstrained) configuration having a proximal portion 220, a distal portion 240, and a lumen 260 extending therebetween. The braided endovascular device 200 is formed from a plurality of elongated members 250 (e.g., wires, pull - out filling tubes, threads, filaments, etc.) woven (or "braided") together. The braided endovascular device 200 includes a non - traumatic member 270 (e.g., a coil, etc.) at the distal portion 240 of the device 200 as shown in Figure 3A. It should be understood that another non - traumatic member 230 can be disposed at the proximal portion 220 of the device 200 (shown in Figure 3B). The individual elongated members 250 can have a generally circular cross - section (Figure 3C) having a cross - sectional diameter in the range of about 0.0005 inches (0.0127 mm) to about 0.003 inches (0.0762 mm). The diameter (D4) of the endovascular device 200 can be in the range of about 0.01 inches (0.25 mm) to about 0.2 inches (5 mm). It should be understood that the individual elongated members 250 can have other suitable cross - sections such as, for example, a rounded rectangular (Figure 3D), a rectangular with right - angled corners (Figure 3E), an oval (Figure 3F), etc. The device 200 can have different shapes, i.e., non - tubular cross - sectional shapes, in its expanded configuration such as a flattened rectangular with rounded corners (not shown).

[0078] The braided intravascular device 200 of FIGS. 3A and 3B is not limited to having the example dimensions described, and it should be noted that the braided intravascular device 200 can have other dimensions. For example, in some embodiments, the braided intravascular device 200 can include a braided structure formed from braided wires, and at least one of the braided wires can have a cross-sectional dimension between 0.0001 inches (0.00254 mm) and 0.001 inches (0.0254 mm). In other embodiments, the braided wire can have a cross-sectional dimension less than 0.00085 inches (0.022 mm), preferably any between 0.0001 inches (0.00254 mm) and 0.0008 inches (0.020 mm), more preferably any between 0.0003 inches (0.0076 mm) and 0.00075 inches (0.019 mm). Alternatively, the braided structure can be formed from ribbon wires, and at least one of the ribbon wires has a thickness of at least 0.0001 inches (0.00254 mm) and a width of up to 0.002 inches (0.0508 mm). In other embodiments, the ribbon wire can have a cross-sectional dimension (width or thickness) less than 0.00085 inches (0.022 mm), preferably any between 0.0001 inches (0.00254 mm) and 0.0008 inches (0.020 mm), more preferably any between 0.0003 inches (0.0076 mm) and 0.00075 inches (0.019 mm). Also, in other embodiments, the braided structure can be formed from one or more twisted wires. Further, in some embodiments, the braided structure can have a number of wires between any of 8 to 96, between any of 16 to 32, between any of 24 to 144, or between any of 24 to 72. Further, in some embodiments, when the braided intravascular device 200 is not constrained outside the delivery catheter, the braided structure can have a braiding angle that is any angle between 20° and 130°, preferably any angle between 20° and 60°.

[0079] Also, in some embodiments, the braided structure of the braided intravascular device 200 can have a tubular configuration. In other embodiments, the braided structure of the braided intravascular device 200 can have a non-tubular configuration. For example, in some embodiments, the braided structure can be a flat braid. A flat braid can be any braided structure having a cross-section with a width W and a thickness T (measured in a direction perpendicular to the width), where the ratio of W / T is the same as or greater than 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20. Also, in some embodiments, the braided structure can be a ribbon braid. In one or more embodiments described herein, the braid can have any width between 0.020 inches (0.5 mm) and 0.197 inches (5 mm), preferably any width between 0.030 inches (0.75 mm) and 0.079 inches (2.0 mm), more preferably any width between 0.030 inches (0.75 mm) and 0.06 inches (1.5 mm). In further embodiments, the braid can have a width of 0.039 inches (1 mm) or more. For example, in one embodiment, the braid can have a width of about 1.25 mm (e.g., 1.25 mm ± 0.1 mm). In some embodiments, the braid can have a braid stiffness of less than 50 mN / mm. Further, in some embodiments, the braid can be formed from a plurality of braided wires of the same size and / or the same composition. In other embodiments, the braid can be formed from a plurality of braided wires of different sizes and / or different compositions.

[0080] In some embodiments, when the braid is unconstrained outside the catheter, the braid can have a first width, and when the braid is inside the catheter, it can elastically collapse and / or bend in a lateral direction (e.g., a direction perpendicular to the longitudinal axis of the braid) to have a second width smaller than the first width. For example, the braid can be a flat braid that is elastically rolled up or coiled to have the second width when inside the catheter and elastically springs out to a relaxed configuration having the first width when deployed outside the catheter.

[0081] As shown in FIG. 3B, the atraumatic member 270 in the distal portion 240 of the braided intravascular device 200 is a first coil segment made from a coil wire. Optionally, the braided intravascular device 200 can also include another atraumatic member 230 in the proximal portion 220. The atraumatic member 230 is, in the illustrated embodiment, a second coil segment. In some embodiments, the coil segment (forming the atraumatic member 230 / 270) can include a coil wire having any cross-sectional dimension between 0.0001 inches (0.00254 mm) and 0.003 inches (0.075 mm), and the first coil segment has a primary coil diameter between 0.003 inches (0.076 mm) and 0.030 inches (0.762 mm). In other embodiments, the braided intravascular device 200 may not include the atraumatic member 230 and / or the atraumatic member 270. The coil forming the atraumatic member 230 / 270 may have a simple shape or a complex shape.

[0082] One or more of the elongate member 250 and / or the atraumatic member 230 / 270 are composed of a disclosed platinum-tungsten (Pt-W) alloy having a tungsten (W) proportion of 10% or more (e.g., 10% - 20%, 10% - 25%, or greater than 25%). When one or more of the elongate member 250 and / or the atraumatic member 230 / 270 are composed of the disclosed platinum-tungsten (Pt-W) alloy, they include the following characteristics. a) Due to the high modulus of elasticity that provides high column strength, the intravascular device 200 includes a better transition between the elongate member 250 and / or the atraumatic member 230 / 270. b) The intravascular device 200 can include a small profile for delivery to the target site of the patient via a small inner diameter catheter.

[0083] In other embodiments, the elongate member 250 can be made from an alloy containing rhenium. For example, the elongate member 250 can be made from a material including a molybdenum-rhenium (Mo-Re) alloy or a tungsten-rhenium (W-Re) alloy. Also, in some embodiments, the material can be further alloyed with Ta, Ir, Rh, Ru, or any combination thereof to enhance the mechanical properties of the material. In further embodiments, the material can be further alloyed with Zr, Hf, Au, or any combination thereof to reduce the magnetic susceptibility.

[0084] In some embodiments, the braided endovascular device 200 can be delivered via a catheter having a lumen for accommodating the braided endovascular device 200. The lumen of the catheter can have an inner diameter of less than 0.020 inches, less than 0.018 inches, less than 0.016 inches, or less than 0.014 inches (e.g., 0.013 inches or less). In other embodiments, the lumen of the catheter can have an inner diameter greater than 0.020 inches, such as 0.04 inches, 0.06 inches, 0.08 inches, 0.1 inches, 0.2 inches, etc.

[0085] In one or more embodiments described herein, the material forming the elongate member 20 / 102 / 250 can have a Young's modulus of 30 Msi or more, 36 Msi or more, or 40 Msi or more.

[0086] Also, in one or more embodiments described herein, the material forming the elongate member 20 / 102 / 250 can have an ultimate tensile strength (UTS) of 350 ksi or more, or 400 ksi or more, or 470 ksi or more, or 500 ksi or more, for example, any value between 500 - 700 ksi.

[0087] According to some embodiments, experiments were conducted on a device made of the disclosed platinum-tungsten (Pt-W) alloy having a tungsten (W) ratio of 10% or more of the device or a part thereof. A sample wire made of the disclosed platinum-tungsten (Pt-W) alloy (Pt-16% W) with a diameter of 0.0011 inches (0.02794 mm) was tested to confirm the properties of the disclosed alloy and compared with commonly used Pt-8% W having the same wire diameter of 0.0011 inches. Both wires showed an elongation of about 2%. The density was 21.08 g / cm 3 The sample wire made of the disclosed platinum-tungsten (Pt-W) alloy (Pt-16% W) with a density of 3 has an ultimate tensile strength (UTS) of 470 Ksi, a Young's modulus of 36 Msi, and a magnetic susceptibility of 23 ppm. In contrast, the commonly used Pt-8% W wire with a density of 21.26 g / cm 3 has an ultimate tensile strength (UTS) of 200 - 250 Ksi, a Young's modulus of 26 Msi, and a magnetic susceptibility of 69 ppm.

[0088] Therefore, a wire made of a platinum-tungsten alloy containing about 16 wt% tungsten showed an improvement of about 100% in mechanical strength, an increase of about 40% in Young's modulus, and a decrease of about 65% in magnetic susceptibility compared to a wire of approximately the same dimensions made of a platinum-tungsten alloy containing about 8 wt% tungsten. Notably, in some embodiments, an implantable medical device can be formed from a wire or filament having the same attributes as the tested wire made of a platinum-tungsten alloy containing about 16 wt% tungsten.

[0089] In other embodiments where the elongated member 20 / 102 / 250 is formed from an alloy containing rhenium, similar mechanical properties can be obtained. For example, the rhenium-containing alloy can have a Young's modulus of 40 Msi or more. The rhenium-containing alloy can have a UTS of 400 ksi or more, for example, any UTS between 500 ksi and 700 ksi.

[0090] Figure 4 shows an example of an implantable medical device 400 according to some embodiments. The implantable medical device 400 includes a braided structure 402 made from a plurality of elongated members 410. Each of the elongated members 410 is a wire made from a Pt-W alloy having a tungsten ratio of about 16 wt% (e.g., 16% ± 2%). Also, each of the elongated members 410 has a cross-sectional dimension of about 0.00075 inches (e.g., 0.00075 inches ± 0.0001 inches). The material of the elongated members 410 has a Young's modulus of 36 Msi and an ultimate tensile strength of 470 ksi. The braided structure 402 is a ribbon braid having a width of about 1.25 mm (e.g., 1.25 mm ± 0.1 mm).

[0091] The implantable medical device 400 has acceptable shape retention characteristics and can be delivered more smoothly using a catheter (e.g., a catheter with a lumen diameter of 0.013 inches) compared to another implantable medical device 500 shown in Figure 5. The implantable medical device 500 in Figure 5 is made from elongated members 510 having similar dimensions to the elongated members 410 and is fabricated by the same process as the implantable medical device 400. However, the elongated members 510 of the implantable medical device 500 are made from a Pt-W alloy having a tungsten ratio of 8 wt%. Compared to the shape retention of the implantable medical device 400 in Figure 4, the loops of the implantable medical device 500 (due to the low Young's modulus of the material being 26 Msi) are either easily deployed, do not bend easily, or plastically deform easily, and as a result, the implantable medical device 500 has undesirable shape retention characteristics. Also, since the Pt-8W material of the implantable medical device 500 has lower mechanical strength than Pt-16W, a braid composed of small-diameter wires is easily damaged during handling and / or processing and / or is easily broken. Sometimes, the wires forming the braid of the implantable medical device 500 may break due to the low UTS of the material (250 ksi).

[0092] As shown in the above embodiments, it is advantageous to fabricate an implantable medical device using an elongated member made from the materials described herein. This is because, due to the high Young's modulus of the material (e.g., higher than that of Pt-8W), an implantable medical device with high axial (column) stiffness and strength can be manufactured. As a result, the implantable medical device may be able to have a smaller size (e.g., cross-sectional dimensions) compared to conventionally known devices. In one application, the implantable medical device may be a vascular occlusion device configured to be delivered to a small blood vessel to occlude an aneurysm. The small blood vessel may be any blood vessel in the body, including distal blood vessels in the patient's brain. Also, due to the high mechanical strength of the materials described herein, the implantable medical device can be smoothly delivered using a small catheter without bending, buckling, and kinking. This is the same even if the size of the medical device is reduced. Further, due to the high UTS of the material, the elongated member forming the implantable medical device will not easily break or fracture during handling and processing. Additionally, due to the high Young's modulus of the material, an implantable medical device can be manufactured using a smaller elongated member to achieve a softer bending stiffness. As a result, the implantable medical device can have a desirable bending stiffness and exhibit better shape retention characteristics.

[0093] In some embodiments, the implantable medical device described herein can comprise a catheter. In such a case, the implantable medical device and the catheter together form a kit. The catheter can have a lumen with a cross-sectional dimension of less than 0.02 inches (e.g., less than 0.014 inches). In some embodiments, the implantable medical device may be a flat braid that is housed within the lumen of the catheter. In such a case, the flat braid can have sufficient column strength to advance relative to the catheter (e.g., the flat braid will not buckle, kink, bend, etc. within the lumen of the catheter while advancing).

[0094] In some embodiments, the implantable medical devices described herein can have a length of any of 0.4 inches (1 cm) to 19.7 inches (50 cm), preferably a length of 2 inches (5 cm) to 11.8 inches (30 cm). In one embodiment, the length is at least 0.4 inches. In another embodiment, the length is at least 1.2 inches. Also, in one or more embodiments, an implantable medical device (e.g., a braid) having any of the lengths described herein is considered to have sufficient column strength when it can be pushed through an elongate lumen without buckling, kinking, or plastic deformation when inserted longitudinally into the elongate lumen. Here, the elongate lumen has a maximum lumen width of 0.03 inches, more preferably a maximum width of 0.2 inches, even more preferably a maximum width of 0.016 inches, and even more preferably a maximum width of 0.014 inches (e.g., 0.013 inches). The elongate lumen can be the lumen of a catheter or any elongate lumen, such as the lumen of a tube used for testing the column strength of the implantable medical device.

[0095] In some embodiments, an implantable medical device described herein is considered to have sufficient shape retention properties when an implantable medical device having a specific initial radius of curvature R1 is inserted into a catheter and has a radius of curvature R2 after being deployed from the catheter. Here, the radius of curvature R2 of the deployed implantable medical device is less than 5 times R1, preferably less than 4 times R1, more preferably less than 3 times R1, and even more preferably less than 2 times R1 (e.g., less than 1.5 times R1).

[0096] As used herein, the term "braid" refers to any structure formed by a plurality of elongated members, and the elongated members may or may not be woven to form the structure. In some embodiments, the braid can have a grid or mesh configuration with an open texture having spaced-apart holes, and the spaced-apart holes may form a uniform pattern or a random pattern. In other embodiments, the braid may have other configurations and may or may not have an open texture. In some embodiments, the elongated members can be joined together by mechanical forces such as frictional forces between the elongated members. By way of non-limiting example, the frictional force that joins the elongated members to form the braid can be created by twisting the elongated members, weaving the elongated members, stacking the elongated members, etc. In other embodiments, the elongated members can be joined together by an adhesive.

[0097] As used herein, the term "about" refers to a variation in value within 10% unless otherwise specified. For example, being "about 10%" or more by weight refers to a weight that is at least 10% ± 1% of the total weight.

Claims

1. 1. A medical device comprising: a braid including elongated members made from an alloy including platinum (Pt) and tungsten (W); The proportion of tungsten (W) in the alloy is 10% by weight or more, The alloy further comprises hafnium (Hf), the proportion of hafnium (Hf) in the alloy being 5% by weight or less; the braid has a first width when the braid is unconstrained on the outside of the catheter and a second width when the braid is inside the catheter; The medical device, wherein the second width is less than the first width.

2. The medical device according to claim 1, A medical device, characterized in that the proportion of tungsten (W) in the alloy is less than 20% by weight.

3. The medical device of claim 1, A medical device characterized in that the alloy has a Young's modulus of 30 Ksi or more.

4. The medical device of claim 1, A medical device, wherein the magnetic susceptibility of the alloy is between 10 ppm and 300 ppm.

5. The medical device of claim 1, The alloy is characterized in that it has a higher ultimate tensile strength and Young's modulus, and a lower magnetic susceptibility, than a platinum-tungsten alloy having a tungsten content of 8% by weight.

6. The medical device of claim 1, The ultimate tensile strength of the alloy is greater than the ultimate tensile strength of a platinum-tungsten alloy having a tungsten percentage of 8% by weight.

7. The medical device of claim 1, A medical device characterized in that the Young's modulus of the alloy is greater than the Young's modulus of a platinum-tungsten alloy containing 8% tungsten by weight.

8. The medical device of claim 1, A medical device, characterized in that the magnetic susceptibility of the alloy is less than the magnetic susceptibility of a platinum-tungsten alloy having a tungsten content of 8% by weight.

9. The medical device of claim 1, The medical device further comprises a catheter.

10. The medical device of claim 9, A medical device, wherein the catheter lumen has a maximum lumen width of less than 0.02 inches.

11. The medical device of claim 9, A medical device, wherein the braid is elastically rolled or coiled while in the catheter.

12. The medical device of claim 1, A medical device, wherein the maximum width of the elongated member is 0.005 inches.

13. The medical device of claim 1, A medical device, wherein the elongate member has a cross-sectional dimension of less than 0.00085 inches.

14. The medical device of claim 1, further comprising: A medical device comprising a coil segment coupled to a distal portion of the braid.

15. The medical device of claim 1, The medical device wherein the alloy has an ultimate tensile strength of 350 ksi or greater.

16. The medical device of claim 1, further comprising: The medical device, wherein the alloy comprises zirconium (Zr).

17. The medical device of claim 16, A medical device characterized in that the combined proportion of hafnium (Hf) and zirconium (Zr) in the alloy is 5% by weight or less.

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