Vascular prosthesis with DFT wire (DRAWN FILLED TUBES)

Abstract

The vascular implant may include at least a first layer having one or more Drawn Filled Tubes (DFT) wires and at least a second layer having one or more non-DFT wires. The first layer may be braided from only a single DFT wire, and the second layer may be braided from multiple non-DFT wires. The vascular implant may also include a connecting wire constructed from a shape memory alloy that is shape-set prior to connection to the one or more implant layers constructed from DFT wires.

Description

[Technical field]

[0001] This application claims priority to U.S. Provisional Application No. 63 / 189,993, entitled “Radiopaque Vascular Prosthesis,” filed May 18, 2021, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Vascular prostheses, such as stents and stent grafts, are used in the vascular system for a variety of reasons, a non-exhaustive list including support to open diseased or blocked vessels to facilitate blood flow, diversion, which involves diverting flow away from a target area such as an aneurysm, and retention of material (e.g., embolic material) within the treatment site to facilitate localized occlusion within the area.

[0003] Visualization remains important for delivery of vascular grafts so that the surgeon can confirm proper placement of the device within the vasculature. Typically, radiography is used for such visualization, which is an imaging technique that uses x-rays, gamma rays, or similar ionizing and non-ionizing radiation to observe the formation of objects within the patient. Specific types of radiography include fixed x-rays, CT scans, and fluoroscopy. For structures to be viewed by most radiographs, they must be relatively radiopaque. Therefore, most implantable vascular grafts often include one or more radiopaque components. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention relates generally to vascular grafts constructed from one or more DFT wires (DRAWN FILLED TUBE).

[0005] One aspect of the invention generally relates to an implant having at least one braided layer comprised of one or more DFT wires and at least one inner braided layer comprised of one or more wires (e.g., DFT wires or non-DFT wires).

[0006] The implant may have a variety of different layer configurations of braided DFT and non-DFT wire layers. For example, the implant may have two braided layers, with an outer layer made of DFT wire and an inner layer made of non-DFT wire, or an outer layer made of non-DFT wire and an inner layer made of DFT wire. In another example, the implant may have three braided layers, with a layer made of DFT wire being the outer, middle, or inner layer, and the remaining two layers made of non-DFT wire being the remaining layers. In another example, the implant may have three braided layers, with a layer made of non-DFT wire being the outer, middle, or inner layer, and the remaining two layers made of DFT wire being the remaining layers. In yet another example, the implant may be configured with four or more layers, with alternating layers of braided DFT and non-DFT wire layers (e.g., a DFT wire layer may comprise the outermost layer, or a non-DFT wire layer may comprise the non-DFT wire layer).

[0007] In addition to having different combinations of DFT and non-DFT wire layers, the implant layers may have different lengths from one another, for example, the braided DFT wire layers may extend beyond the proximal and / or distal ends of the non-DFT wire layers, or the non-DFT wire layers may extend beyond the proximal and / or distal ends of the DFT wire layers.

[0008] Another aspect of the present invention is generally directed to a vascular implant (e.g., a stent or graft) having one or more connecting wires, preferably non-DFT wires and composed of a shape memory material, preformed (e.g., heat set) into a desired secondary shape and then connected and / or braided to one or more braided layers of the implant. By preforming the connecting wires into a desired secondary shape, the connecting wires provide additional force to the implant to achieve its desired expanded shape size and may help maintain the expanded shape, especially in tortuous vessels. As discussed herein, DFT wires are relatively flexible compared to non-DFT wires, especially after heat setting. Thus, the connecting wires preformed to a desired expanded size may help to compress other layers of the implant, including the layer with the DFT wire, to achieve or maintain a desired radial size and potentially better fixation within the patient's vasculature.

[0009] The implant may include one layer, two layers, three layers, or more than two layers. The implant may also include at least one layer braided from DFT wires, or optionally multiple layers (e.g., two or three) braided from DFT wires. As in the previous embodiment, the remaining layers may be constructed from non-DFT wires.

[0010] The preformed connecting wires may form a helical shape or may be one or more circular shapes. A single connecting wire may be used with the implant, or multiple connecting wires may be used with the implant. The connecting wire or wires may each extend along the entire length of the stent (or a majority of the length of the stent), or the connecting wire or wires may extend along only a small portion of the length of the implant (e.g., a quarter, a third, a half, or three quarters of the length of the implant).

[0011] Multiple separate connecting wires may be used in a non-overlapping configuration. For example, one connecting wire may extend along the front half of the implant and a second connecting wire may extend along the back half of the implant. Similar configurations are possible with three, four, five, six or more connecting wires. Alternatively, multiple connecting wires may be arranged such that only a portion of each connecting wire overlaps at a location along the length of the implant.

[0012] The connecting wires can be connected to one or more implant layers by braiding one or more connecting wires through each implant layer and / or by connecting one or more connecting wires to wire locations on the stent via a connecting mechanism, such as a weld, a ring, a wire coil, a wire tie, wrapping the ends of the connecting wires, or similar techniques. Connecting wires may only be used in single layer stent embodiments to aid in opening the implant, in two layer stent embodiments to aid in connecting the layers, or in three or more layer stent embodiments to aid in connecting at least two of the implant layers and generate additional radial opening force.

[0013] In one example, the connecting wire is a shape memory alloy such as Nitinol. The connecting wire may be preformed by wrapping around a mandrel to form a desired size and pattern, and then heat-setting to establish the desired secondary shape of the connecting wire. The connecting wire may then be connected (e.g., braided or secured) to one or more layers of the implant. The connecting wire may have a shape similar to one or more portions of the wire of the layers of the implant (i.e., it may closely follow the shape of one portion of the wire of the implant), or it may have a different pattern / shape than the wire portion of the implant. [Brief description of the drawings]

[0014] These and other aspects, features, and advantages enabled by embodiments of the present invention will become apparent and apparent from the following description of embodiments of the invention and from reference to the accompanying drawings.

[0015] [Figure 1] FIG. 1 shows a cross section of a DFT wire used in a DFT stent according to one embodiment.

[0016] [Figure 2A] FIG. 2A shows a side view of a dual-layer DFT stent according to one embodiment.

[0017] [Figure 2B] FIG. 2B shows a photographic side view of the dual-layer DFT stent of FIG. 2A according to one embodiment.

[0018] [Figure 3A] FIG. 3A shows an end view of the dual layer DFT stent of FIG. 2A according to one embodiment.

[0019] [Figure 3B] FIG. 3B shows a photographic end view of the dual-layer DFT stent of FIG. 2A according to one embodiment.

[0020] [Figure 3C] FIG. 3C shows a close-up view of an end loop of a dual-layer DFT stent according to one embodiment.

[0021] [Figure 4] FIG. 4 shows a close-up view of the dual-layer DFT stent of FIG. 2A according to one embodiment.

[0022] [Diagram 5] FIG. 5 shows a close-up view of the dual-layer DFT stent of FIG. 2A according to one embodiment.

[0023] [Figure 6] FIG. 6 shows a close-up view of the dual-layer DFT stent of FIG. 2A according to one embodiment.

[0024] [Figure 7] FIG. 7 shows a close-up view of the dual-layer DFT stent of FIG. 2A according to one embodiment.

[0025] [Figure 8] FIG. 8 shows an end view of another embodiment of a stent in accordance with one embodiment.

[0026] [Figure 9] FIG. 9 shows an end view of another embodiment of a stent in accordance with one embodiment.

[0027] [Figure 10] FIG. 10 shows a connecting wire on a mandrel according to one embodiment.

[0028] [Figure 11] FIG. 11 shows connecting wires connected to stent wires according to one embodiment.

[0029] [Figure 12] FIG. 12 shows a side view of a single layer stent according to one embodiment.

[0030] [Figure 13] FIG. 13 shows an end view of an end loop configuration of a DFT stent according to one embodiment.

[0031] [Figure 14] FIG. 14 shows an end view of an end loop configuration of a DFT stent according to one embodiment.

[0032] [Figure 15] FIG. 15 shows a plan view of an end loop configuration of a DFT stent according to one embodiment.

[0033] [Figure 16] FIG. 16 shows a side view of a stent having a reinforcing member according to one embodiment.

[0034] [Figure 17] FIG. 17 shows a close-up view of a stent having a reinforcing member according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Specific embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and should not be construed as being limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. The terms used in the detailed description of the embodiments shown in the accompanying drawings are not intended to limit the present invention. In the drawings, like numbers refer to like elements. Although different embodiments are described, the features of each embodiment can be used interchangeably with other embodiments described. In other words, any of the features of each of the embodiments can be combined and adapted with each other, and the embodiments should not be strictly construed as necessarily including only the features shown or described.

[0036] Although the embodiments described herein are generally referred to as stents, the teachings herein are applicable to a wide range of different vascular devices, such as grafts, valves, fixation mechanisms, or other vascular medical devices that include at least one braided portion, and thus the term stent should be understood to include all of these devices.

[0037] This specification also describes several different features of the stent, such as different wire materials in different layers, different layer arrangements, different layer lengths, different connections between layers, and other features. Any of these aspects can be used and substituted for each other. Thus, while every permutation of the features is not specifically described, such combinations are specifically contemplated as part of the present invention and are supported by the specification.

[0038] This specification also refers to the use of DFT wires (Drawn Filled Tubes) and non-DFT wires. The non-DFT wires 16 can be composed of materials typically used in medical devices, including shape memory alloys (e.g., Nitinol), stainless steel, cobalt-chromium, polymers, or other materials. In some embodiments, shape memory alloys, particularly Nitinol, may be preferred. These non-DFT wires 16 are generally composed of a single material across their cross-section, although coatings and similar features are possible.

[0039] The DFT wire 10 can be constructed from a variety of different materials having different cross-sectional thicknesses. For example, FIG. 1 shows a cross-section of a DFT wire 10 having an inner core 12 constructed from a first material and an outer jacket 14 constructed from a second material. In another example, the outer jacket 14 can be constructed from multiple layers of different materials (e.g., two or more layers on the inner core 12) alternating. Either the inner core 12 or the outer jacket 14 can be constructed from a radiopaque material (e.g., platinum, gold, tantalum, palladium, or similar known radiopaque materials). Either the inner core 12 or the outer jacket 14 can be constructed from a non-radiopaque material (i.e., a material with relatively low or no radiopacity). Such non-radiopaque materials include, for example, stainless steel, cobalt-chromium, or shape memory alloys such as Nitinol. In one example, the inner core 12 can be constructed from a radiopaque material and the outer jacket 14 can be constructed from a non-radiopaque material. In another example, the inner core 12 may be constructed from a non-radiopaque material and the outer jacket 14 may be constructed from a non-radiopaque material.

[0040] In one example, the inner core 12 may be constructed from a radiopaque material and the outer jacket 14 may be constructed from a shape memory alloy such as Nitinol. The radiopaque material facilitates visualization of the DFT wire 10, while the outer jacket 14 allows for good flexibility and the ability to have a memorized shape (e.g., via heat setting). In another example, the inner core 12 may be constructed from platinum or tantalum and the outer jacket 14 may be constructed from Nitinol-1 or Nitinol-2.

[0041] The inner core 12 may have a cross-sectional shape that is circular, elliptical, or oval, although various other shapes such as rectangular, triangular, etc. may also be used. The outer jacket 14 may be tubular in shape with an inner diameter that closely matches the outer diameter of the inner core 12. In other words, the outer jacket 14 may include an interior lumen through which the inner core 12 extends.

[0042] Additionally, once the DFT wire 10 is heat treated / heat set, it may exhibit higher flexibility and lower stiffness than a pure metallic shape memory wire. This may generally be surprising since the inclusion of a radiopaque material in the inner core 12 (depending on which particular material is used) is generally stiffer compared to the metallic shape memory outer jacket 14. However, the inclusion of two separate materials in the fabrication of a single wire may alter the material properties of the combined wire form. Due to these properties, if the DFT wire 10 is used in a stent, the design aspects of the stent must compensate for this increased flexibility, particularly to facilitate proper deployment and proper placement of the DFT stent at the treatment site and to prevent stent migration. The embodiments presented herein address these and other issues to fabricate a usable DFT stent.

[0043] The outer diameter of the DFT wire 10 can have a wide range of diameters depending on its use within the stent. For example, the DFT wire 10 can have a diameter within the inclusive range of about 0.001 inches to 0.004 inches, or about 0.0025 inches to about 0.003 inches. The inner core 12 and outer jacket 14 of the DFT wire 10 may be comprised of various percentages of the cross-section of the DFT wire 10 based on cross-sectional width or diameter. For example, the inner core 12 may be within the inclusive range of 5% to 30% of the cross-sectional width or diameter of the DFT wire 10, with the remaining percentage being the outer jacket 14 (i.e., 95% to 70%). In a more specific example, the ratio may be 10% for the cross-sectional width or diameter of the inner core 12 and 90% for the cross-sectional width or diameter of the outer jacket 14.

[0044] In some examples, the overall cross-sectional width or diameter of DFT wire 10 is within the inclusive range of about 0.0018 inches to about 0.0022 inches. In some examples, inner core 12 (e.g., comprised of a radiopaque material) has a width or diameter within the inclusive range of about 0.0005 inches to about 0.001 inches, or within the inclusive range of about 0.0008 inches to about 0.0009 inches.

[0045] Any of the wires 10, 16 used in the stent can be functionalized, for example with poly(MEA-co-APMA).

[0046] One aspect of the present invention is generally directed to a stent having at least one braided layer comprised of one or more Drawn Filled Tubes (DFT) wires and at least one braided inner layer comprised of one or more wires (e.g., DFT wires or non-DFT wires).

[0047] The stent can have a variety of different layer configurations of braided DFT and non-DFT wire layers. For example, the stent may have two braided layers, with an outer layer composed of one or more DFT wires and an inner layer composed of non-DFT wires, or with an outer layer composed of non-DFT wires and an inner layer composed of DFT wires. In another example, the stent may have three braided layers, with a layer composed of DFT wires being the outer, middle, or inner layer, and the remaining two layers composed of non-DFT wires being the remaining layers. In another example, the stent may have three braided layers, with a layer composed of non-DFT wires being the outer, middle, or inner layer, and the remaining two layers composed of DFT wires being the remaining layers. In yet another example, the stent may be composed of four or more layers, alternating between braided DFT and non-DFT wire layers (e.g., a DFT wire layer may constitute the outermost layer, or a non-DFT wire layer may constitute a non-DFT wire layer).

[0048] In addition to having different combinations of DFT and non-DFT wire layers, the stent layers may have different lengths from one another, for example, the braided DFT wire layers may extend beyond the proximal and / or distal ends of the non-DFT wire layers, or the non-DFT wire layers may extend beyond the proximal and / or distal ends of the DFT wire layers.

[0049] 2A-7 show one particular embodiment of a stent 100 having at least one layer comprised of one or more DFT wires 10 and at least one layer comprised of one or more non-DFT wires 16. More specifically, the stent 100 includes a braided outer layer 102 forming a tubular shape comprised of one or more outer wires 112 that are DFT wires 10, and a braided inner layer 104 forming a tubular shape within the outer layer 102 comprised of one or more inner wires 114 that are non-DFT wires 16. The DFT wire 10 may have any of the characteristics described above, but preferably has an inner core 12 comprised of a radiopaque material and an outer jacket 14 comprised of a shape memory alloy (e.g., Nitinol).

[0050] The use of a radiopaque material with the DFT wire 10, and particularly with the inner core 12, can provide several advantages. First, the outer layer 102 of the DFT wire 10 may be radiopaque and therefore show up in radiographic visualization. Unlike the use of relatively small radiopaque markers, the entire outer layer 102 is visualized, which allows the physician to better view and position the stent 100. Since radiopaque markers may not be necessary, the absence of such markers may further reduce the profile or thickness of the stent.

[0051] Additionally, when a radiopaque material is used in the DFT wire 10, it has relatively more flexibility or bendability than many non-DFT wires 16 that are constructed from shape memory alloys (e.g., Nitinol) due to the properties of the material used in the DFT wire 10 and / or after it has been heat set to impart a shape to the wire. Thus, a stent layer constructed from one or more DFT wires 10 may better conform to the shape of a tortuous anatomical site within a patient.

[0052] Stent 100 also includes several other features, described further below, which may be useful, but are not required, in connection with the stent layers of DFT wire 10 and non-DFT wire 16. Note that the portions of Figure 2A labeled as Figures 4-7 correspond to enlarged views in the figure. Each of Figures 4-7 and Figure 2B show photographic views of Figure 2A.

[0053] In one example, the stent 100 may include a tubular outer layer 102 and a tubular inner layer 104 attached to the outer layer 102. The outer layer 102 may be configured to anchor the stent 100 within the patient, while the inner layer 104 may be less porous than the outer layer 102 to avoid diverting or impeding blood flow.

[0054] Both the inner layer 104 and the outer layer 102 may be braided in a helical braid pattern such that the wires have the same or similar braid angles, allowing both layers 102 and 104 to increase and decrease in length at the same or similar rates as the stent 100 radially expands or contracts between its radially compressed and its radially expanded configurations. Alternatively, the layers 102, 104 may have different braid patterns and / or braid angles.

[0055] The outer layer 102 may have a larger pore size or lower picks per inch (PPI) than the inner layer 104. In one example, when the stent 100 is in its expanded configuration, the pores may be sized within the inclusive range of about 0.3 mm to about 0.5 mm. In another example, the braided tubular portion of the outer layer 102 may have a picks per inch within the inclusive range of about 60 PPI to about 85 PPI, more specifically about 72. However, in some embodiments, the pore / cell size and / or picks per inch of each layer 102, 104 may be the same or similar.

[0056] The outer wire 112 of the outer layer 102 may have a larger diameter than the inner wire 114 of the inner layer 104. For example, the outer wire 112 of the outer layer 102 may have a diameter within the inclusive range of about 0.001 inches to 0.004 inches, or about 0.0025 inches to about 0.003 inches. In one example, the outer wire 112 of the outer layer 102 may have a diameter of about 0.0016 inches throughout its braided tubular portion and about 0.0020 inches along the portions of the outer wire 112 that form its end loops 106, 109.

[0057] The outer layer 102 may be braided into its tubular shape from a single outer wire 112 (e.g., DFT wire 10). Alternatively, the outer layer 102 may be braided into its tubular shape from multiple outer wires (e.g., DFT wire 10). Also, in other embodiments, these outer layer shapes may use non-DFT wires 16 instead. Example diameter sizes for the outer layer 102 in its expanded shape include 2.5 mm to 3.0 mm, 3.5 mm to 4.5 mm, 4.5 mm to 5.0 mm, 5.0 mm to 5.5 mm, 5.5 mm to 6.0 mm, and 6.0 mm to 8.0 mm, with various lengths.

[0058] The inner layer 104 may be braided into its tubular shape from a single inner wire 114 (e.g., a non-DFT wire 16). Alternatively, the inner layer 104 may be braided into its tubular shape from multiple inner wires 114 (e.g., non-DFT wires 16). Also, in other embodiments, these inner layer shapes may use DFT wires 10 instead. The inner layer 104 may form a braided tubular shape that is sized to expand to an outer diameter equal to or approximately equal to the inner diameter of the outer layer 102. The inner layer 104 may be comprised of one or more inner wires 114 (e.g., 20, 24, 36 wires) braided together to form its tubular shape. In either example wire, the wire diameter is approximately 0.00085 inches, and in an exemplary embodiment, may be braided to form approximately 165 picks per inch.

[0059] The outer layer 102 may form a braided tubular shape with multiple end loops that may be the same size or different sizes. The loops may be located at the proximal end, the distal end, or both ends. Each end of the braided tubular portion may have, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or more loops. The loops may have larger and smaller sizes, such as the larger loop 106 and the smaller loop 109 in FIG. 3A. These larger and smaller loops 106, 109 may form an alternating pattern, as seen in FIG. 3A, with five larger and five smaller loops interleaved with one another. Note that FIG. 3B is a photographic representation of FIG. 3A.

[0060] 6, the ends of the outer wires 112 may be positioned near each other, such as about three-quarters of the way along the length of the stent 100. The wire ends may be positioned to overlap each other, and then one or more (e.g., four) laser welds 112A may be fabricated to connect portions of the wires 112, thereby preventing the end or ends of the wires 112 from being easily exposed in an arrangement that would cause injury to the patient. Alternatively, the wire ends may have other connection mechanisms, such as being tied together or placed under separate coils or bands.

[0061] When a DFT wire 10 including a radiopaque inner core 12 is used, additional radiopaque markers may not be necessary. However, depending on which layer incorporates the radiopaque DFT wire 10, radiopaque markers may be useful, particularly to help identify where the stent 100 terminates at the ends of the stent 100. In one example, as shown in FIG. 3C, the end loops 106 of the outer layer 102 may include one or more wire coils 108 (or sleeves, tubes, or similar shapes) wrapped around a portion of the outer wire 112 of the end loops 106. The wire coils 108 may be constructed of a radiopaque material, such as tantalum, and may help indicate the ends of the stent 100 during imaging and provide additional fixation. However, non-radiopaque materials may be used instead. In one example, each end includes four tantalum wire coils 108, each positioned near the apex or furthest end of each end loop 106, and / or each coil 108 may be formed from tantalum wire having a diameter of approximately 0.0015 inches. Alternatively, the wire coils 108 may be constructed from a non-radiopaque material, such as Nitinol, and may serve only for fixation purposes.

[0062] The coil 108 can be positioned at a location on the loop 106 (or optionally loop 109). As seen in FIG. 3C, the coil 108 can be positioned closer to the end of the loop or closer to the body of the stent. The embodiment of FIGS. 2A-7 shows only the larger loop 106 with the coil 108 positioned relatively close to the end of the loop 106. In another embodiment, the loop 106 may be positioned closer to the body of the stent (i.e., the left-most coil 108 as shown in FIG. 3C). In this example, the coil 108 is further positioned within the smaller loop 109 such that it remains within the smaller loop 109 when the stent is in both its radially compressed and radially expanded configurations. Because loops 106 and 109 move somewhat relative to one another during radial expansion, this positioning helps prevent the coil 108 from moving relative to the wire of the smaller loop 109, allowing for a smoother opening movement of the stent 100. In another example, the loop may include two coils 108 in both an inner and outer position, as seen in FIG. 3C.

[0063] FIG. 8 illustrates another embodiment of a stent 100 ′ that is generally similar to the embodiment of the stent 100 previously described, but in which the outer layer 102 is constructed from non-DFT wire 16 and the inner layer 104 is constructed from DFT wire 10 .

[0064] FIG. 9 shows another embodiment of a stent 100″ that is generally similar to the embodiment of stent 100 described above, but includes a third outer layer 103. Both the third outer layer 103 and the inner layer 104 may be composed of non-DFT wire 16, and the middle layer 102 may be composed of DFT wire 10. Alternatively, a combination of DFT wire 10 and optional non-DFT wire 16 may be used for each layer. For example, all layers may be composed of DFT wire 10, only one of layers 102, 103, 104 may be composed of DFT wire 10 and the remaining layers may be composed of non-DFT wire 16, or two of layers 102, 103, 104 may be composed of DFT wire 10 and the remaining layers may be composed of non-DFT wire 16.

[0065] Another aspect of the present invention is generally directed to a vascular device (e.g., a stent or graft) having one or more connecting wires 116, which are non-DFT wires 16, preferably constructed from a shape memory material, preformed (e.g., heat set) into a desired secondary shape and then connected and / or braided into one or more braided layers of the stent. By preforming the connecting wires 116 into a desired secondary shape, the connecting wires 116 can provide additional force to the stent to achieve and / or maintain its desired open configuration size. As previously mentioned, the DFT wires 10 are relatively flexible compared to the non-DFT wires 16, depending on their material configuration. Thus, the connecting wires 116 preformed to a desired expanded size can help to compress other layers of the stent, including the layer having the DFT wires 10, to achieve a desired radial size and potentially better anchor within the patient's vasculature.

[0066] The stent may include one layer, two layers, three layers, or more than two layers. The stent may also include at least one layer braided from DFT wire 10, and optionally multiple layers (e.g., two or three) braided from DFT wire 10. As in the previous embodiment, the remaining layers may be constructed from non-DFT wires 16.

[0067] The preformed connecting wires 116 may form a helical shape or may be one or more circular shapes. A single connecting wire 116 may be used with a stent, or multiple connecting wires 116 may be used with a stent. The connecting wire(s) 116 may each extend along the entire length of the stent (or a majority of the length of the stent), or the connecting wire(s) 116 may extend along only a small portion of the length of the stent (e.g., a quarter, a third, a half, or three quarters of the length of the stent).

[0068] Multiple separate connect wires 116 may be used in a non-overlapping configuration. For example, a first connect wire 116 may extend along the first half of the stent and a second connect wire 116 may extend along the second half of the stent. Similar configurations are possible for three, four, five, six, or more connect wires 116. Alternatively, multiple connect wires 116 may be arranged such that only a portion of each connect wire overlaps at their locations along the stent length.

[0069] The connecting wires 116 are connected to one or more stent layers by braiding one or more connecting wires 116 through each of the stent layers and / or by connecting one or more connecting wires 116 to wire locations on the stent via a connection mechanism such as a weld, a ring, a wire coil, a wire tie, wrapping the ends of the connecting wires 116, or similar techniques. The connecting wires 116 may only be used in single layer stent embodiments to aid in opening the stent, in two layer stent embodiments to aid in connecting the layers, or in three or more layer stent embodiments to aid in connecting at least two of the stent layers and generate additional radial opening force.

[0070] In one example, the connecting wire 116 may be any shape memory material, such as Nitinol. The connecting wire 116 may be pre-formed by wrapping around a mandrel to form a desired size, shape, and pattern, and then heat set to establish a desired secondary shape for the connecting wire 116. The connecting wire 116 may then be connected (e.g., interwoven or secured) to one or more layers of the stent. The connecting wire 116 may have a shape similar to one or more portions of the wires of the layers of the stent (i.e., may closely follow the shape of one portion of the wires of the stent), or may have a different pattern / shape than the wire portions of the stent.

[0071] Although the connector wires 116 are described as being preformed, they may be interwoven with one or more layers of the stent and heat set with other layers of the stent.

[0072] 2A-7, the use of one or more connecting wires 116 is illustrated. In the final form of the stent 100, the one or more connecting wires 116 may be disposed adjacent a portion of the outer wire 112 in a helical pattern such that the connecting wire or wires 116 have a similar braid axis and braid angle as the outer wire 112. Again, a single connecting wire 116 may be used, or multiple connecting wires 112 in different arrangements / positions may be used.

[0073] The connecting wire 116 may be interwoven with both wires 112 and 114 of both layers 102 and 104 (e.g., in an over-and-under pattern through both) so that both layers are adjacent to one another and positioned relatively close together. Similar braid angles allow the wires 112, 114, and 116 of the stent to move in relative unison as they contract / extend during radial expansion and contraction. In one particular example, two helically interwoven connecting wires 116 are included, although one, three, four, five, six, or more connecting wires 116 may also be included.

[0074] By preforming and / or heat setting the connecting wires 116, the diameter and pitch of the helix may be set to perform similarly to the wires 112, 114 that form the inner and outer layers 102, 104. This is clinically advantageous because all components will radially expand and contract similarly, allowing the stent 100 to open and better conform to tortuous anatomy, providing better wall apposition, thus reducing or eliminating stent opening and stability issues.

[0075] In this embodiment of stent 100, connect wire 116 may be comprised of one or more Nitinol helical wires (i.e., helical, heat set, secondary shape). Using such Nitinol helical wires or coils instead of non-shape memory wires allows stent 100 to open to larger sizes (e.g., larger outer diameters (OD), such as 5 mm or more) because the pre-formed and heat-set shape of connect wire 116 creates additional outward radial force depending on the pre-formed size of connect wire 116 and the other expanded sizes of other layers of stent 100.

[0076] In some embodiments, the connecting wire 116 may also, or instead, be electropolished prior to use in connecting the inner and outer layers 102, 104. However, it should be understood that in some embodiments, the connecting wire 116 may not be electropolished prior to use in connecting the inner and outer layers 102, 104.

[0077] As seen in FIGS. 5 and 7, the ends of the connecting wire 116 may be connected or secured to the outer wire 112 of the outer layer 102 (and / or optionally the inner wire 114 of the inner layer 104) to help prevent the connecting wire 116 from unwinding or uncoupling from the two layers 102, 104. In one example, a coiled wire tie 110 (e.g., a non-DFT wire 116 such as tantalum or a non-superelastic alloy) may be used to connect the connecting wire 116 to the wire 112. In another example, each end of the connecting wire 116 may be wrapped around the wire 112. These coiled wire ties 110 may be connected in a manner that allows the wires 112 and 114 to move somewhat relative to one another, or may be rigidly connected in a manner that prevents the wires 112 and 114 from moving relative to one another. The coiled wire ties 110 may also be optionally used to connect both layers 102 and 104 separately from the connecting wire 116.

[0078] If the connecting wire 116 is not constructed from a shape memory alloy such as Nitinol, it may instead be constructed from a radiopaque material to improve visualization. However, non-shape memory wires may be more difficult to configure to impart a desired amount of radial expansion force to achieve a relatively large expanded stent size, especially with one or more wires constructed from the flexible DFT wire 10. Depending on many different factors, especially in tortuous or curved vessels, the two layers 102 and 104 may also exert forces on each other and attempt to move away from each other. Preformed shape memory materials / alloys such as Nitinol, when used for the connecting wire 116, act somewhat elastically and return to their original shape / configuration after a stress of deployment, whereas other materials that do not have such superelastic properties may permanently change shape depending on the magnitude and direction of the force applied during stent placement. As such, such configurations with connecting wires constructed from shape memory materials can create a more elastic stent that is more resistant to damage.

[0079] Additionally, the shape memory material, such as Nitinol, of the connecting wire 116 allows the connecting wire 116 to be heat set or preformed during the manufacturing process. This preforming allows the connecting wire 116 to assume the shape of a helical coil having a predetermined diameter and pitch, similar to the wires of the inner layer 104 and the outer layer 102, but with a different radial diameter to impart a force to the other stent layers, for example. Thus, the preformed connecting wire 116 allows for different heat set diameters of the helical coil (or other shape) of the connecting wire 116 in the expanded configuration versus after the layers 102 and 104 are expanded. In that regard, the layers 102 and 104 of the stent may be heat set after being braided, separate from the connecting wire 116, and the connecting wire 116 may be later connected and / or braided to the remaining layers 102, 104.

[0080] Thus, all three components, layers 102, 104, and connecting wire 116, expand radially and contract longitudinally in a similar manner, despite size differences, and present less resistance or force to one another, allowing stent 100 to open to larger diameters (e.g., 5.0 mm or more) than would be possible with a connecting wire material that does not otherwise have superelastic properties (e.g., tantalum), thereby providing better vessel wall apposition.

[0081] In this regard, this embodiment of the stent 100 is specifically comprised of a single braided DFT wire 112 having a radiopaque inner core 12 and may include an outer layer 102 having a first configuration (e.g., braid / winding pattern / angle, wire diameter), an inner layer 104 comprised of one or more braided inner wires 114 having a second configuration (e.g., braid / winding pattern / angle, wire diameter), and one or more pre-formed connecting wires 116 (e.g., Nitinol) that connect the inner and outer layers 102, 104 together (e.g., helically braided wires and / or coiled wires).

[0082] As discussed above, the connecting wires 116 may be used with other stent embodiments having other layer configurations. For example, FIG. 12 shows a single layer stent 140 that is generally similar to the outer layer 102 of the stent 100 discussed above. The wire 112 may be heat set DFT wire 10, and thus has relatively high flexibility. One or more connecting wires 116 may be connected and / or interwoven with the stent 140 in any of the configurations discussed above to provide the performance benefits (e.g., expansion and fixation) discussed above.

[0083] In other examples, the stents 100' and 100" of Figures 8 and 9 may also include one or more connecting wires 116 similar to any of the configurations previously described. The connecting wires 116 may be further braided and / or connected between only two layers or all layers. Additionally, different connecting wires 116 may be connected to different pairs of stent layers.

[0084] It should also be appreciated that different materials other than the aforementioned Nitinol may be used for the connecting wires 116. As a further example, the connecting wires 116 may be constructed from DFT or tantalum wire. However, Nitinol or DFT connecting wires 116 have been shown to provide better stent diameter recovery to keep the layers 102, 104 together when compared to tantalum connecting wires 116.

[0085] The present invention also includes methods of manufacturing a stent by preforming or heat setting the shape of the connecting members 116 and then connecting and / or braiding / weaving the connecting members 116 to one or more stent layers.

[0086] One particular exemplary method is described with respect to the bilayer stent 100 of FIGS. 2A-7, but is applicable to any of the embodiments herein. In such a method, as seen in FIG. 10, a shape-memory connecting wire 116 (e.g., Nitinol) may be wrapped around a fixture or mandrel 130. The connecting wire 116 may be wrapped to have a coil angle that matches the coil angle of one of the wire portions of the outer layer 102. The mandrel 130 may include guides, grooves, or similar physical features to help achieve a desired helical diameter and pitch. Optionally, the mandrel 130 may have a larger diameter than the mandrel on which the remaining stent layers 102, 104 are braided. The connecting wire 116 may then be heat set on the mandrel 130 to retain its coil shape and size. The connecting wire 116 may be further processed or finished as needed, such as by polishing, passivating, etching, or pickling.

[0087] The interwoven outer layer 102 and inner layer 104 may then be brought together, or optionally braided on top of each other, such that the inner layer 104 is positioned and aligned within the outer layer 202. The layers 102 and 104 may be heat set on a mandrel to set a predetermined radial size in the expanded configuration. Optionally, the diameter size of this mandrel may be smaller than the diameter size of the mandrel 130. The connecting wire 116 is then braided through both layers 102 and 104, generally following a similar path adjacent to one of the outer wires 112, but may otherwise pass over and under both wires 112 and 114. As a result, the connecting wire 116 may have its helical heat-set configuration interwoven with and generally congruent with one or both of the other two layers 102, 104 (shown in FIG. 11). Alternatively, the connecting wire may be braided in a helical direction that is the opposite (opposite pitch) rotational direction of the helical direction of the outer wire 112. Alternatively, connecting wire 116 may be disposed between layers 102 and 104 without being interwoven with the layers.

[0088] When the connecting wire 116 is in its desired position, as seen in FIG. 11, a wire tie or coil 110 (or other previously described connection mechanism) can be formed at each end of the connecting wire 116. The wire tie 110 can be formed by wrapping a wire (e.g., tantalum) around both the connecting wire 116 and a portion of the outer wire 112. Alternatively, the wire of the tie 110 can be wrapped around the inner wire 114. Alternatively, the end of the connecting wire 116 can be wrapped around the outer wire 112 to form the wire tie 110, but the non-shape memory material can provide greater resistance to deformation, thereby providing a stronger connection point. Additionally, wire ties 110 (or similar connections) can be included at other locations along the length of the connecting wire 116.

[0089] It should be understood that the pitch of the connecting wire 116 varies along the length of the stent 100 as the connecting wire 116 is braided through the layers 102, 104 of the stent 100. As an example, the pitch of a first winding of the connecting wire 116 may be different than the pitch of a second winding of the connecting wire 116. In addition, the direction of the windings may vary in different embodiments, with one exemplary embodiment using right-handed windings and another exemplary embodiment using left-handed windings. Furthermore, the outer diameter of the windings of the connecting wire 116 may vary in different embodiments.

[0090] The stent 100 of Figures 2A-7 includes five relatively large loops 106 and five relatively small loops 109. However, additional numbers of loops and sizes of loops are possible. In this regard, any of the stents described herein may include a plurality of larger loops 106 and smaller loops 109 forming an alternating pattern at one or more of its ends. For example, Figure 13 shows a stent 142 having four pairs of alternating larger and smaller loops 109. In another example seen in Figure 14, a stent 144 may include six pairs of larger and smaller loops 106, 109. In addition, embodiments having only one size of end loop are possible (e.g., all loops may be substantially uniform in size). For example, Figure 15 shows a stent 146 including eight similarly sized loops 106. The embodiments of Figures 13-15 are particularly suitable for stents having a diameter greater than 5.00 mm, such as between about 6.0 mm and 8.0 mm, improving the opening and stability of the stent.

[0091] The long flare / loop 106 and the short flare / loop 109 may each be oriented at an angle of about 60 degrees (relative to a horizontal plane extending through the axial / radial center of the stent). The size of the flare / loop may also vary with the size of the stent. In various examples, the stent is sized at about 2.5-5 mm in diameter. In some embodiments, the stent may be sized greater than 5 mm in diameter, such as between 6-8 mm in diameter. This particular size fits into neurovascular arteries that are smaller than most arteries of the vasculature, and provides an advantage as a scaffolding stent used to provide support to the neck of the aneurysm for subsequent devices (e.g., embolic coils or other occluding agents) used to fill the aneurysm. Proper apposition of the stent is particularly helpful in this targeted treatment plan to ensure that the stent does not migrate from the aneurysm site, which could lead to migration of embolic material when left without a supporting scaffold.

[0092] Any of the stent embodiments herein may include one or more reinforcing elements that serve to further increase the force with which the stent radially expands. For example, Figures 16 and 17 show an embodiment of a stent 150 that is similar to stents 100 or 140. However, one or more regions of stent 150 may include reinforcing elements 152 disposed over stent wire 112 (which may be DFT wire 10) to introduce increased strength and stiffness along one or more regions. It should be understood that the number, size, positioning, and orientation of such reinforcing elements 152 may vary in different embodiments.

[0093] In a typical braided stent, it may be difficult to fully expand the proximal end of the stent once the remaining portion of the stent is deployed. This may be particularly due to the tortuous vascular anatomy in which the stent is deployed. This problem may be magnified as stents are designed to be less stiff and more flexible, such as by using heat-set DFT wires 10. Thus, introducing one or more reinforcing elements 152 along a portion of the stent 150, such as the proximal, distal, or intermediate regions of the stent 150, may help increase the opening force along this region and promote easier deployment. These reinforcing elements 152 may also be used in combination with the connecting wires 116 described above, such that both components provide radial expansion force to the stent 150.

[0094] The reinforcing element 152 may, in one example, comprise a coil as shown in more detail in FIG. 17, where the reinforcing coil is wound around the DFT stent wire 112 of the stent 150. In other embodiments, as shown in FIG. 16, the reinforcing element 152 may comprise a tube that is placed over the DFT wire 152 along one or more regions of the stent. In one embodiment, the reinforcing element 152 may be attached (e.g., by adhesive or welding) to the wire 112 to fix its position. In another embodiment, the reinforcing element 154 may not be fixed and may be free to move (e.g., by sliding and / or rotating). In another embodiment, the reinforcing element 154 may be a separate linear wire element that is attached to a portion of the DFT wire 112 to "thicken" the associated DFT wire portion.

[0095] The reinforcing element 152 may be fabricated from a strong shape memory material, in one example, a preferred example is Nitinol (e.g., either a Nitinol coil or Nitinol tube), but other examples may include Cobalt-Chromium or Stainless Steel.

[0096] 17, when the reinforcing element 152 is a coil, the coil can have an associated stiffness or k-value associated with it. This stiffness / k-value depends on several attributes, such as the material composition, the thickness of the coil, and how tightly the reinforcing coil is wound (i.e., pitch). Higher k-values ​​can be achieved, for example, by utilizing a relatively stiff material (e.g., a radiopaque material such as gold, platinum, tungsten, palladium, tantalum, or a hard non-radiopaque metal), by using a tightly wound pitch in the coil, and / or by adjusting the coil properties (e.g., the thickness of the wire that comprises the coil, the overall width of the coil, and the overall length of the coiled reinforcing element 152).

[0097] The portion of the wire 112 underlying the reinforcing element 152 has a stiffness with a k value associated with it since the wire forming the reinforcing element 152 has a corresponding "springiness" due to being helically, longitudinally wound along the stent 150. Note that this "springiness" increases as the stent 150 is compressed and helps urge the stent 150 open during deployment. The k value of the wire 112 is determined by the stiffness of the associated DFT wire, the diameter of the wire, and the pitch of the wire with the DFT stent 150 (in other words, the helical / longitudinal winding pattern used to mechanically wrap the stent 150).

[0098] The stent region shown in FIG. 17, where the reinforcing coil sits on a portion of the wire 112, can be thought of as two parallel springs, with Hooke's Law resulting in corresponding stiffnesses. If the wire 112 has an associated stiffness k1 and the reinforcing coil 152 has an associated stiffness k2, then the overall stiffness of this region will be (k1+k2), or in other words, the combined stiffness will be higher. In this manner, the reinforcing element 152 serves to increase the associated stiffness in that region. This increased stiffness has certain advantages, such as, for example, reinforcing certain regions of the stent 150 to increase deployment forces (helping the stent open) and promote apposition against the vessel wall along the reinforcement.

[0099] Another advantage is that the increased stiffness and increased area that the reinforcing elements occupy over the underlying wires aids in the opening of adjacent cells of the stent 150. If adjacent cells are unable to open sufficiently, they will contact the reinforcing elements 152 (which have a larger surface area than the underlying and surrounding wires 112) and the force of this contact can aid in the opening of these other cells.

[0100] The reinforcing elements 152 may be located in one or more regions along the DFT stent 150. For example, they may be located at approximately equidistant intervals along the length of the stent 150 (or alternatively, at random locations) to promote consistent expansion and consistently enhanced stiffness throughout the stent. Alternatively, they may be located only along the proximal end of the stent 150 (as shown in FIG. 16 ) at one or more locations along the proximal end to enhance the strength and opening of the proximal region of the stent.

[0101] In an exemplary embodiment, a pair of reinforcing elements 154 may be positioned at locations along the radial circumference of stent 150. In such embodiments, reinforcing elements 152 may be aligned with one another along a longitudinal axis extending through the length of stent 150. Additional reinforcing elements 152 may be positioned at various other radial locations around stent 110, such as on opposite sides, in such embodiments, as needed to increase the stiffness of stent 150.

[0102] In other exemplary embodiments, the location of the reinforcing element 154 may be different than that shown in the figures. For example, in some embodiments, the reinforcing element 152 may instead or additionally be located at or near the tip region of the stent 150. As a further example, the reinforcing element 152 may instead be located on opposing windings such that it is at a different angle than that shown in the figures.

[0103] The reinforcing elements 152 can be added to the DFT wires 112 of the stent 150 in a variety of ways. Whether the DFT stent 150 has only one DFT wire or multiple DFT wires, the following techniques can be used: In one embodiment, the reinforcing elements 152 can be slid over the respective wire sections before or during the wrapping procedure used to wrap the stent 150.

[0104] In another embodiment, the wire can be cut near the area where the reinforcing element 152 will be added to the wire, and once the reinforcing element 152 is properly positioned, the wire can then be soldered or welded to the other cut section of the wire to reattach the two wire sections. One advantage of locating this wire attachment location close to the reinforcing element 152 is that it can thicken the associated wire section, helping to hold the reinforcing element 152 in a particular position and preventing it from moving around.

[0105] In one example, the reinforcing element 152 is a coil of Nitinol having an inner diameter of about 0.003 inches and an outer diameter of about 0.0065 inches. If multiple reinforcing elements 152 are used, they can be spaced in various ways, for example, one winding of wire can separate two elements 152, more windings of wire can separate the two elements, or the elements 152 can be spaced directly adjacent to each other on adjacent windings.

[0106] 2A-7, and elsewhere, primarily describes the use of DFT wire 10 to construct the outer layer 102, although alternately, wires made entirely of radiopaque material, such as gold, platinum, tungsten, platinum-tungsten, palladium, iridium, platinum-iridium, rhodium, tantalum, barium sulfate, bismuth subcarbonate, bismuth oxychloride, bismuth trioxide, or combinations thereof, may be used. Thus, one aspect of the invention includes a stent having a first braided layer braided from one or more radiopaque wires and a second braided layer braided from one or more shape memory wires, the two layers being connected to one another.

[0107] In one embodiment, the invention includes a stent having at least one layer braided from one or more wires, and the at least one braided layer forming a stent body having a tubular shape and having a plurality of longer loops and a plurality of shorter loops disposed at its proximal end, its distal end, or both its proximal and distal ends, the plurality of longer loops and the plurality of shorter loops forming an overlapping and alternating pattern, and a radiopaque marker disposed on at least one of the plurality of longer loops adjacent to the stent body such that adjacent ones of the plurality of short loops do not contact or migrate past the radiopaque marker.

[0108] The term shape setting as used herein refers to a secondary shape imparted to a wire or similar component comprised of a shape memory alloy such as Nitinol. Typically, such shape setting occurs by the application of heat when the component is placed into a desired shape, such that the component may return to its original shape after deformation within a certain temperature range.

[0109] The term "about" is used herein in connection with various numbers (e.g., dimensions). Use of this term should be understood to complement numbers within a range of 5% above and below the given number.

[0110] It should be understood that different aspects of the embodiments herein are interchangeable and combinable with one another. In other words, additional embodiments are specifically contemplated by combining different features from different embodiments. Thus, although specific embodiments are shown in the figures, the present invention is not necessarily intended to be limited to only those specific combinations.

[0111] Although the present invention has been described with respect to specific embodiments and applications, those skilled in the art will be able to create additional embodiments and modifications in light of the present teachings without departing from the spirit or beyond the scope of the claimed invention. It is therefore to be understood that the drawings and descriptions herein are provided by way of example to facilitate understanding of the invention and should not be construed as limiting its scope.

[0112] Terms:

[0113] Exemplary embodiments are described in the following numbered sections.

[0114] Item 1. A method of manufacturing a stent includes wrapping a shape memory connector wire around a fixture, heat setting the shape of the shape memory connector wire, and braiding the shape memory connector wire through an outer stent layer and an inner stent layer positioned within the outer stent layer.

[0115] Item 2. A method of forming a stent includes the steps of braiding a first stent layer, shaping the first stent layer to have a second shape having an expanded tubular shape of a first diameter, shaping a connecting wire to have an expanded shape of a second diameter that is the same size as, larger or smaller than the first diameter, and connecting the connecting wire to at least the first stent layer.

[0116] Item 3. A method of manufacturing a stent includes forming a first stent layer by braiding at least one first stent wire into a first tubular shape, forming a second stent layer by braiding one or more second stent wires into a second tubular shape, and connecting the first stent layer to the second stent layer.

[0117] Clause 4. The method of any of the preceding clauses, wherein manufacturing the stent further comprises forming a third stent layer by braiding one or more third stent wires into a third tubular shape and connecting the third stent layer between the first stent layer and the second stent layer.

[0118] Clause 5. The method of any of the preceding clauses, wherein the stent further comprises connecting the first stent layer to the second stent layer and / or the third stent layer by one or more connecting wires.

[0119] Clause 6. A method of delivering a stent includes disposing a stent in a radially compressed state within a delivery catheter, advancing the delivery catheter to a target location within a blood vessel, and releasing the stent from the delivery catheter within the blood vessel such that the stent expands to a radially expanded state, wherein releasing the stent from the delivery catheter includes actuating an implant detachment mechanism.

[0120] Clause 7. The method of clause 6, wherein the stent includes a first layer braided from a DFT wire and a second layer braided from a non-DFT wire.

[0121] Clause 8. The method of clause 6, wherein the stent comprises at least one layer braided from DFT wires, and the connecting wires comprise a shape memory material preformed to have an expanded shape.

Claims

**Claim 1** Having at least one first stent wire braided in a first tubular shape, the at least one first stent wire having an outer stent layer with DFT wires, and an inner stent layer having one or more second stent wires braided in a second tubular shape, the stent wherein the outer stent layer is connected to the inner stent layer. **Claim 2** The stent according to claim 1, wherein the second stent wire has the DFT wire. **Claim 3** The stent according to claim 1, wherein the second stent wire has non-DFT wires. **Claim 4** Further comprising a third stent layer having one or more third stent wires braided in a third tubular shape, the third stent layer being disposed between the outer stent layer and the inner stent layer, the outer stent layer being disposed within the inner stent layer, or the outer stent layer being disposed within the third stent layer, the stent according to claim 1. **Claim 5** The stent according to claim 1, wherein the outer stent layer is braided with only a single said DFT wire. **Claim 6** The stent according to claim 5, wherein the inner stent layer is braided with a plurality of wires made of a non-DFT material. **Claim 7** Further comprising one or more connecting wires connected to the outer stent layer and the inner stent layer, the one or more connecting wires being made of a shape memory material and being shaped to have a secondary shape before connection to the outer stent layer and the inner stent layer, the stent according to claim 1. **Claim 8** The stent according to claim 7, wherein the secondary shape of the one or more connecting wires has a diameter larger than the expanded diameter of the stent. **Claim 9** The stent according to claim 7, wherein the secondary shape of the one or more connecting wires is helical. **Claim 10** The stent according to claim 9, wherein the pitch of the helical secondary shape of the one or more connecting wires is substantially the same as the braiding pitch of the at least one first stent wire. **Claim 11** A first coil disposed around a first tip of one of the one or more connection wires and around a first portion of the at least one stent wire, and a second coil disposed around a second tip of one of the one or more connection wires and around a second portion of the at least one stent wire. The stent according to claim 9, further comprising:

12. The stent according to claim 7, further comprising a first connection wire connected along a first region of the stent and a second connection wire connected along a second region of the stent.

13. The stent according to claim 1, further comprising one or more connection wires connected to the first stent layer, the one or more connection wires being composed of a shape memory material and heat set to have a secondary shape before connection to the first stent layer.

14. The stent according to claim 13, wherein the one or more connection wires are braided with the outer stent layer and the inner stent layer.

15. The stent according to claim 13, wherein the secondary shape of the one or more connection wires has a diameter larger than the expanded diameter of the stent.

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