An improved vascular system and an unbraided high-performance microcatheter having permeability characteristics and responses to lesions

Abstract

The disclosed embodiments of the microcatheter comprise an inner tube extending from a distal tip to a proximal hub. One embodiment of the microcatheter includes a first inner coil wound around a length of the inner tube, a second intermediate coil wound around the first coil in a winding direction or orientation different from that of the first coil, and a third outer coil wound around the proximal portion of the second coil in a winding direction or orientation different from that of the second coil. In one disclosed embodiment, the first, second, and third coils include distal ends that terminate together at a common location spaced proximally from the distal tip on the distal side. To improve flexibility while maintaining sufficient axial force transmission and torque capabilities, a gap between one or more of the first, second, or third coils may be provided between groups or segments of the wire filaments forming the coils. An outer layer of polymeric material is provided around the coils, and the polymer may have a decreasing hardness or stiffness and an increasing softness and flexibility as it moves distally from proximal along the microcatheter.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of Provisional Application No. 63 / 365,715, filed on June 2, 2022, entitled "HIGH PERFORMANCE MICROCATHETERS", the entire content of which is incorporated herein by reference.

[0002] Description of Research and Development Sponsored by the Federal Government Not applicable

[0003] This disclosure relates to intravascular access using microcatheters.

Background Art

[0004] A catheter is a medical device that includes a lumen for passing devices such as fluids and / or guidewires. There are many catheters in this field for various medical purposes. Examples include U.S. Patent Nos. 7,981,091; 9,636,477; 9,782,561; 10,065,331; 10,166,363; 10,238,834; 10,258,767; 10,493,234; 10,835,283, and 10,912,921.

[0005] A microcatheter is generally a catheter having an outer diameter of less than about 1.25 mm, and most microcatheters have a diameter of less than about 1.0 mm. Some microcatheters are not required to have stringent performance characteristics and tend to be constructed inexpensively. Other microcatheters are required to traverse difficult, tortuous blood vessels within patients who are not in good health. Such catheters can be difficult to construct, and in some cases, some performance characteristics may be sacrificed in favor of other performance characteristics.

[0006] Some microcatheters are designed for use within or near the brain. Such devices are designed to be highly flexible, which makes them unsuitable for use in applications involving tortuous or semi-occluded paths. The flexibility of such catheters is useful for crossing the base of the skull, but due to that same flexibility, it becomes useless for other applications, including many in the peripheral vascular or coronary systems. Intravascular microcatheters for peripheral or coronary access may be designed to include a passage for a 0.014-inch guidewire.

[0007] Percutaneous intravascular procedures such as angioplasty (with and without stent insertion), lithoplasty, atherectomy, thrombus removal, and lithoplasty may be used to treat intravascular targets. In an exemplary case, for example, angioplasty and / or atherectomy may be used to effectively treat below-the-knee (“BTK”) lesions, restore blood flow, and improve the likelihood of limb salvage, thereby treating BTK lesions. The technical success of intravascular procedures for treating exemplary lesions such as BTK lesions initially depends on the ability to cross the target lesion. The choice of vascular access is considered extremely important in the intervention of exemplary BTK lesions. Various options for vascular access are available, including radial artery access, ipsilateral femoral access, contralateral femoral access, and retrograde distal access. See, for example, Li, Y. et al. Antegrade vs crossover femoral artery access in the endovascular treatment of isolated below-the-knee lesions in patients with critical limb ischemia, Journal of Endovascular Therapy 2017; 24(3):331-6.

[0008] To reach an anatomical target of interest, such as a lesion or an occlusion within a blood vessel, in the direction of the flow of body fluids such as blood, an antegrade catheter may be used. An antegrade catheter generally has to traverse a long distance from the percutaneous access point to the target lesion, such as a BTK lesion, compared to the typical crossing distance in the case of a retrograde catheter. As a result, pushability, i.e., axial force transmission, torsional resistance, and torque are performance parameters required for an antegrade catheter.

[0009] A retrograde catheter may be used to pass through a lesion in a direction opposite to the flow of body fluids such as blood. Advantages of retrograde passage may include that the distal or retrograde side of the lesion may be softer or more easily accessible in shape compared to the proximal or antegrade side of the lesion. Generally, a retrograde microcatheter may have a small-diameter distal profile, a smaller crossing profile than an antegrade microcatheter, and may further have a more flexible distal profile than an antegrade microcatheter, which, as described, generally requires maximum pushability and torque to reach a target within a blood vessel.

[0010] A microcatheter can generally be used to obtain collateral vessel access among various vascular accesses. In some cases, the microcatheter generally used in a retrograde approach may be the best option for a surgeon, while in other cases, the surgeon may prefer the microcatheter generally used in an antegrade approach. The embodiments of the microcatheter described herein are not intended to be limited to retrograde or antegrade.

[0011] A microcatheter includes a variety of performance factors and characteristics, including at least one or more of rigidity, torque transmission, size (e.g., length, inner diameter, and outer diameter), crossing profile, flexibility, torsional resistance, softness, and other characteristics. SUMMARY OF THE INVENTION

[0012] There is a need for high-performance microcatheters having an upward vascular system and lesion passage properties and responses. Some of the elements contributing to passage properties include a small passage profile, particularly an optimal flexibility range in the distal region of the microcatheter, and effective torque transmission within an optimal range, preferably a bi-directional torque application response for at least one rotation in both the clockwise and counterclockwise directions, a desirable combination.

[0013] Embodiments of the present disclosure address these issues, among others.

[0014] Embodiments of the disclosed microcatheter include an inner tube extending from a distal tip to a proximal hub. One embodiment of the microcatheter includes a first inner coil wound around a length of the inner tube, a second intermediate coil wound around the first coil in a winding direction or orientation different from that of the first coil, and a third outer coil wound around a proximal portion of the second coil in a winding direction or orientation different from that of the second coil. In one disclosed embodiment, the first, second, and third coils include a distal end that terminates at a common position spaced proximally from the distal tip on the distal side. To improve flexibility while maintaining sufficient axial force transmission and torque capabilities, a gap between one or more of the first, second, or third coils may be provided between groups or segments of the wire filar forming the coils. An outer layer of a polymeric material is provided around the coils, and the polymer may have a decreasing hardness or rigidity and an increasing softness and flexibility as it moves distally from proximal along the microcatheter.

[0015] The disclosed microcatheter may be used in conjunction with a steerable guidewire to access and / or pass through regions of the coronary and / or peripheral vasculature, or other vascular targets. The disclosed microcatheter may also be used to support a guidewire when passing through a lesion, or to facilitate the placement and exchange of guidewires and other interventional devices, and to selectively inject / deliver diagnostic and therapeutic agents, and / or to deliver contrast agents to the coronary, peripheral vasculature, and abdominal or other vasculature.

[0016] The microcatheters of the present disclosure include embodiments of a shaft configuration that provide improved passageability and other performance characteristics, including, among other things, a passage profile, flexibility of the distal region, pushability, torque response, and torsional resistance.

[0017] It should be understood that the invention is not limited by the embodiments described herein. Instead, the invention can be used in arteries, veins, and other body vasculatures. By varying the size of the disclosed embodiments, the embodiments may be suitable for peripheral vascular, coronary, and neurological applications. Other features and advantages of the invention will become more apparent from the following detailed description of the invention when read in conjunction with the accompanying exemplary drawings.

Brief Description of the Drawings

[0018]

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DETAILED DESCRIPTION OF THE INVENTION

[0019] The following description refers to the accompanying drawings, which show specific embodiments of the present invention. Other embodiments having different structures and operations do not depart from the scope of the present invention.

[0020] Referring generally to FIGS. 1 - 4, an embodiment of an exemplary microcatheter 100 will be described. The catheter has an elongate body 110, which comprises an inner polymer tube or liner L or coating that forms at least a portion of a single inner lumen having an inner diameter 21 and an outer diameter 25, and defines the longitudinal axis AX of the microcatheter 100. The elongate body 110 further comprises a proximal region 14, an intermediate or transition region 15, and a distal region 16, as well as a tapered distal tip T, with the smallest outer diameter at the distal, tapered end, which outer diameter can preferably be in the range of about 0.4 mm to about 0.6 mm, although the outer diameter at the distal end of the distal tip T can be larger or smaller than 0.4 mm - 0.6 mm. The preferred outer diameter at the distal end of the distal tip T is approximately 0.48 mm.

[0021] As best seen in FIG. 2, the distal tip portion T has an outlet 20 of the inner lumen and an inner diameter 20. The lumen is preferably defined by a polymeric inner liner extending towards the outlet 20 along the axis AX. The liner L may be provided by any suitable material or coating such as polytetrafluoroethylene (PTFE), silicone, or other lubricious materials or coatings that provide a surface and / or lumen for passing, in some embodiments, interventional devices, guidewires, infusion fluids, drugs, etc. In one embodiment, the outlet 20 is formed when the liner L extends throughout to the outlet 20 of the distal tip T. Alternatively, the lumen may be provided by the inner portion of the innermost coil 91, which may be coated in some embodiments with a layer of polymer or other similar material. The lumen may be suitable for the purpose of passing a guidewire of 0.014 inches or other size.

[0022] The outer diameter 25 of the distal region 16 of the elongate body 110 is preferably less than about 1.25 mm, more preferably less than about 1.0 mm, even more preferably less than about 0.8 mm, and may be greater than the smallest outer diameter of the tapered distal tip T extending distally over a distance from the distal end of the distal region 16. A particularly preferred outer diameter of the distal region 16 may be approximately 0.71 mm. In certain embodiments, the passage profile of the distal region 16 may be 2.1F.

[0023] The microcatheter optionally includes a hub 13 operably connected to the coil assembly 1 and / or the inner liner L. The hub 13 may comprise any suitable handle that can be grasped by hand, such as a 2, 3, or 4-wing hub, which may include an inlet I in fluid communication with the lumen of the inner liner. Alternatively, the inner liner L may extend distally along the length of the hub 13 to provide a long lumen through the hub 13. An optional strain relief 12 may be connected to the hub 13.

[0024] The distal end of the strain relief 12 may define the working length 22 of the catheter 100. The working length is preferably from about 115 cm to about 200 cm, more preferably from about 135 cm to about 150 cm. The strain relief 12 may be made of a material having a softer hardness than the material forming the hub 13.

[0025] The microcatheter 100 preferably includes one or more synthetic layers surrounding the coil assembly 1. One or more synthetic layers are illustrated as including regions 3, 4, 5, 6, 7, 8, 9, and 23, although more or fewer discrete regions may be utilized. As best seen in FIG. 2, region 3 is made of a polymeric material used to form the distal tip T. The synthetic regions are preferably polymers or elastomers, more preferably polymeric elastomers. The materials of portions 4, 5, 6, 7, 8, 9, and 23 may include polyethylene, polyvinylpyrrolidone, polypropylene, polyethylene terephthalate, polyamide, polyester, or polyurethane, or combinations thereof. Examples include Vestamid, Pellethane, Carbotan, nylon (e.g., Aesno 12 nylon or Grilamid), Hytrel, Pebax, or polyolefin. Preferably, the materials of portions 4, 5, 6, 7, 8, 9, and 23 do not increase in hardness in the direction from the proximal portion P to the distal portion D along the length of the catheter, and preferably decrease in hardness. In one embodiment, the hardness continuously decreases in the distal direction. The distal tip T of region 3 may be formed from a polymer selected from the above-listed polymers and / or may be made of a material having a hardness equivalent to that of region 4.

[0026] Section 14 has an outer diameter, which may be larger than the outer diameter of section 15, and the outer diameter of section 15 may be larger than the outer diameter of section 16. The difference in the outer diameters may be achieved by providing a thicker composite layer in section 14 and / or 15. In addition to providing pushability and torque imparting properties, the larger outer diameter, at least in section 16, results in a less abrupt transition with respect to the stiffness of the strain relief 12, so that additional strain relief can be provided to the system.

[0027] In one embodiment, the outer portion of the elongate body 110 may be coated along its length with a material (e.g., a hydrophilic material or a hydrophobic material or a combination thereof) that reduces the coefficient of friction to facilitate insertion and tracking through the vasculature.

[0028] The composition and length of the polymer portions 4, 5, 6, 7, 8, 9, and 23 are preferably diverse in order to impart the desired structural properties to the catheter 100. Examples of various structures of the polymer portions are set forth in Table 1 provided below. It should be noted that, as will be appreciated by those skilled in the art, materials different from those disclosed in Table 1 may be used to impart the desired characteristics of the microcatheter 100.

[0029] The intermediate or transition region 15 is adjacent to the proximal side of the distal region 16, and the outer diameter of the intermediate or transition region 15 may be slightly larger than the outer diameter of the distal region 16. In one embodiment, the outer diameter of the intermediate or transition region 15 may preferably be less than 1.1 mm, more preferably less than about 0.95 mm, and even more preferably less than 0.9 mm. A particularly preferred outer diameter of the intermediate region 15 may be 0.84 mm.

[0030] The proximal region 14 is located adjacent to the proximal side of the intermediate or transition region 15 and has an outer diameter that may be larger than the outer diameter of the intermediate or transition region 15. The preferred outer diameter of the proximal region 14 may preferably be less than 1.0 mm. A particularly preferred outer diameter of the proximal region 14 may be approximately 0.95 mm.

[0031] Generally, the outer diameter of the elongated body 110 may transition from the smallest outer diameter at the distal end of the distal tip T to the largest outer diameter in the proximal region 14. If present, the transitioning outer diameter of the elongated body 110 may comprise a tapered increase in outer diameter that changes smoothly from distal to proximal. Stated another way, the outer diameter may comprise a decrease that changes smoothly while moving from the proximal region 14 to the distal end of the distal tip T. In other embodiments, at least a portion of the transition of the outer diameter of the elongated body 110 may comprise a stepped or gradually increasing outer diameter that moves in the proximal direction.

[0032] Accordingly, the outer diameter of the tube portion or body 110 may be constant or may increase, taper, or increase in steps while moving in the proximal direction. The shape of the smoothly tapering decrease in outer diameter while moving in the distal direction helps control the mechanical properties of the catheter to avoid buckling during axial loading or translation.

[0033] Generally, the outer diameter of the tube portion or body 110 may vary along its length as described above, but the inner diameter of the lumen defined by the inner tube or liner L may be constant along its length. A preferred inner diameter of the lumen may be less than about 0.55 mm. A particularly preferred inner diameter of the lumen may be approximately 0.43 mm. Alternatively, in some embodiments, the inner diameter of the lumen may comprise a smoothly tapering decrease while moving in the distal direction.

[0034] Catheter 100 has a support assembly that includes coil assembly 1. The illustrated embodiment does not include a braid, but some alternative embodiments may include a braid.

[0035] Referring to FIGS. 2 and 5, an exemplary coil assembly 1 is formed from one or more filaments F and includes at least a first innermost filament coil 91 wound in a first winding direction about an axis AX. The coil assembly 1 also includes a second coil 93 disposed around or outside the first coil 91 and formed from one or more filaments F wound in a second winding direction different from the first winding direction about the axis AX. The coil assembly 1 also includes a third coil 95 disposed around or outside the second coil 93 and formed from one or more filaments F wound in a third winding direction different from the second winding direction.

[0036] Continuing to refer generally to FIGS. 1 - 4 and particularly to FIGS. 5 - 6, the coil assembly 1 includes at least a first innermost coil 91 wound in a first winding direction about an axis AX. The coil assembly further includes a second coil 93 which surrounds at least a portion of the first coil 91 and is wound in a second winding direction different from the first winding direction about the axis AX. The coil assembly 1 also includes a third coil 95 wound in a third winding direction about at least a portion of the second coil 93 and in a winding direction different from the second winding direction. In each case, as will be further described later, the first coil 91 may be wound around the outer surface of the inner liner L, the second coil 93 may be wound around the first coil 91, and the third coil 95 may be wound around the second coil 93. FIG. 5 shows three exemplary coils 91, 93, 95 and the different winding directions of each coil 91, 93, 95.

[0037] At least one of the coils 91, 93, and 95 may extend over a length different from the remaining coils from the proximal portion P of the catheter 100 towards the distal portion D of the catheter 100. Stated differently, each distal end of the coils 91, 93, 95 may be disposed proximally spaced from the distal end of the distal tip T, and at least one of the proximal spacing distances between the distal ends of the coils 91, 93, and / or 95 is different from the proximal spacing distances of the remaining coils 91, 93, 95.

[0038] Continuing to refer to FIG. 1, as shown in FIG. 6, in some embodiments of the exemplary microcatheter 100, a coil assembly 1 may be provided that extends along a portion of the distal region 16 of the microcatheter 100 and terminates at a common location or point proximal to the distal end of the distal tip T on the distal side. Thus, the distal ends of the first, second, and third coils 91, 93, and 95 of the coil assembly 1 are located proximal to the distal end of the microcatheter 100 and the distal end of the distal tip T as shown.

[0039] In an alternative embodiment, two coils, for example 91, 93, may be provided as the first coil 91 and the second coil 93 as described herein, and the distal ends of the two coils 91, 93 are at a common location proximal to the distal end of the microcatheter 100 along the inner liner L. In this embodiment, the first coil 91 is an inner coil that surrounds at least a portion of the inner liner L and has a first winding direction. The second coil 93 is the outermost coil in this embodiment, surrounds at least a portion of the inner first coil 91, and has a second winding direction different from the first winding direction.

[0040] The distance between the distal end of the distal tip T and the distal ends of the first, second, and third coils 91, 93, 95 of the coil assembly 1 forming the triple coil is shown as element 19 in FIG. 2, and this distance 19 may be less than about 10 mm, more preferably less than about 5 mm, more preferably about 1 mm, but these distances are merely exemplary and other distances are within the scope of the invention described herein.

[0041] In some embodiments, the three-coil portion of the coil assembly 1 extends proximally through a strain relief element 12 and, in some embodiments, may extend into the hub 13 as shown in FIG. 3.

[0042] The different winding directions of coils 91, 93, and / or 95 enable a microcatheter that can rotate in each opposite direction with substantially equal torque application forces, and thus provides a microcatheter capable of bidirectional rotation that resists elongation and shortening during rotation in either direction. Additionally, the disclosed microcatheter is capable of performing multiple rotations in one direction, e.g., clockwise or counterclockwise, and substantially equal torque application forces are generated or produced with each rotation.

[0043] As described above, the first and most inner coil 91 comprises one or more filaments F wound in an exemplary helical or spiral configuration in a first winding direction. The second intermediate coil 93 is formed from one or more filaments F wound in a second winding direction different from the first winding direction around the first and most inner coil 91. Finally, the third and most outer coil 95 is formed from one or more filaments F wound in a third winding direction different from the first winding direction around the second intermediate coil 93.

[0044] The windings of the first, second, and third coils 91, 93, 95 are illustrated as spiral or helical, but as will be readily appreciated by those skilled in the art, other winding configurations may be used, including but not limited to varying the winding pitch (angle) of the filament F with respect to the longitudinal axis of the coil assembly 1. The winding configurations of the coils 91, 93, 95 may also be used to affect performance characteristics such as stiffness, flexibility, pushability, torque application, and buckling resistance along the coil assembly 1.

[0045] In practice, coils 91, 93, and 95 may be continuously fabricated by winding one or more filaments F about axis AX. When an inner liner L is present, the first inner coil 91 may be wound about the liner L, followed by winding the second intermediate coil 93 about the first inner coil 91, and finally winding the third outer coil 95 about the second intermediate coil 93. Alternatively, a removable cylindrical mandrel may be used to provide the shape of the inner liner L, about which wire or filament F is wound, and by defining axis AX, coils 91, 93, and 95 may be continuously formed. After assembly of the coil assembly 1, the mandrel may be removed and an inner liner L or polymeric coating may be inserted or applied into the inner lumen defined by the first coil 91.

[0046] An exemplary embodiment of a coil assembly 1 comprising first, second, and third coils 91, 93, and 95 is shown in FIG. 5. Each of the first, second, and third coils 91, 93, 95 further comprises a plurality of filament groups 97, each filament group 97 comprising an exemplary number of 18 filaments F with no spacing between adjacent wires within that filament group 97. It is noted that the coil assembly 1 comprising first, second, and third coils 91, 93, 95 may be elastically deformed by extending or bending the coil assembly 1 during vessel crossing or during an intervention procedure. One skilled in the art will recognize that a gap G between adjacent wires that are not attached or connected to each other may be created during deformation by extension or bending. However, in an undeformed configuration, the wires or windings within the filament group 97 have no gap between adjacent wires.

[0047] The number of filaments F constituting one filament group 97 and / or the width or diameter of the individual filaments F within the first, second, and third coils 91, 93, 95 may be constant or equal along the length of coils 91, 93, 95, or may decrease distally along coils 91, 93, 95.

[0048] Furthermore, one or more of coils 91, 93, and / or 95 may comprise one or more yarn groups 97 defined by a gap G. In some embodiments, one or more of coils 91, 93, and / or 95 may not have a gap G that defines a yarn group 97, and the remaining coils may comprise one or more gaps G that define one or more yarn groups 97.

[0049] Preferably, adjacent wires or yarns F within the yarn group 97 are not connected to each other and are not attached to each other. As described above, when the microcatheter 100 comprising the coil assembly 1 bends to guide a bend within the vasculature, the yarn F elements can accommodate the bend by spreading apart on the outer radius of the bend and thus on the outer radius of the coil assembly 1, allowing sufficient flexibility to make the necessary bend. Thus, in some cases it may be preferable not to connect at least a portion of adjacent yarns F in order to provide maximum flexibility.

[0050] However, in some embodiments, one or more adjacent yarns F within one or more yarn groups 97 may be connected to or attached to each other. In some embodiments, the proximal region of one or more of the coils 91, 93, 95 may comprise at least some adjacent yarns F that may be connected to each other, while the distal region of one or more of those coils 91, 93, 95 may comprise adjacent yarns F that are not connected to each other to increase the flexibility of the distal region of the coil assembly 1.

[0051] Whether to connect or attach at least some adjacent yarns F within one or more of coils 91, 93, 95 can affect performance characteristics such as stiffness, flexibility, torque imparting ability, pushability, and buckling resistance, among others. Additionally, the attachment or non-attachment of at least some adjacent yarns F of coils 91, 93, 95 may be used in combination with features that affect the performance described herein.

[0052] As shown in FIG. 5, while it is perhaps preferable to have 18 filaments F in one filament group 97, this is also exemplary and other numbers of wires or filaments F may be used. The number of filaments F in one filament group 97 is preferably from about 2 to about 50 filaments F, more preferably from about 6 to about 24 filaments F, more preferably from about 10 to 20 wires or filaments F, and even more preferably from about 16 to 18 filaments F. Rigidity, flexibility, pushability, torque imparting property, and / or buckling resistance may be affected by the selection of the number of filaments F within the filament group 97. Thus, a particular embodiment of the coil assembly 1 may comprise one or more coils 91, 93, 95 having an equal number of filaments F in each filament group 97. Other embodiments may comprise an unequal number of filaments F in each filament group 97. For example, without limitation, the proximal region of one or more coils 91, 93, 95 may comprise one or more filament groups 97 having a greater number of filaments F than the number of wires or filaments F in one or more filament groups 97 within the distal region of one or more coils 91, 93, 95, to achieve a stiffer proximal region and a more flexible distal region. As a substantial result of the unequal number of filaments F within the filament group 97, the spacing between adjacent filament groups 97 having an unequal number of filaments F becomes unequal. Similar results are obtained when filaments F of different widths are used within adjacent filament groups 97.

[0053] Thus, the number of filaments F in each filament group 97 within the coil assembly 1 comprising one or more of the coils 91, 93, 95 can be used to adjust performance characteristics such as rigidity, flexibility, pushability, torque imparting property, and / or buckling resistance. Further, the number of filaments F in each filament group 97 within the coil assembly 1 comprising the coils 91, 93, 95 may be used in combination with one or more of the features that affect the performance described herein.

[0054] As shown in FIG. 5, in some embodiments, one or more of the coils 91, 93, 95 may include at least one gap G between one or more pairs of adjacent yarn groups 97 to achieve a desirable balance of stiffness, flexibility, pushability, torque imparting property, and buckling resistance. When two or more gaps G are provided in any coil, those gaps G may be longitudinally spaced from each other. The number of gaps G (frequency of gaps G) over a defined distance may increase from the proximal portion to the distal portion of the catheter. Additionally or alternatively, in other embodiments, the width of the gap G may increase distally along the length of the catheter 100. Alternatively, the width of the gap G may decrease distally.

[0055] To provide the gap G, during construction of the outer coil 95, one element may be removed from 19 elements of yarn, leaving 18 yarn elements and the gap G. Alternatively, one or more wires or yarns may be wound about the axis AX as further described herein.

[0056] At least one gap G may optionally be provided in the first and second coils 91, 93. The width of the gap G may preferably be the width of the yarn F or approximately 0.01 inches. In other embodiments, the gap G may be less than about 0.01 inches or greater than about 0.01 inches. The width of the gap G may or may not be equal along the length of the coil assembly. In some embodiments, the width of the gap along one or more proximal regions of the coil assemblies 91, 93, 95 may be less than or equal to the width of the gap along one or more distal regions of the coil assemblies 91, 93, 95. The width of the gap G may, in some embodiments, gradually increase while moving proximally to distally along one or more of the coil assemblies 91, 93, 95. In other embodiments, a step change in the width of the gap G may occur in one or more of the coil assemblies 91, 93, 95 while moving proximally to distally.

[0057] In addition, the gap G may be used to define the yarn group 97, in which case the gap G defines the space or separation between adjacent yarn groups 97. In some embodiments, the gap G may define an outer peripheral space. In other embodiments, a partial outer peripheral space may be defined by the gap G, where one or more yarns F cross a portion of the gap G between adjacent yarn groups 97. In some embodiments, a combination of an outer peripheral gap G and a partial outer peripheral gap G may be provided.

[0058] The gap G is preferred but may not be present in some embodiments and may only be present along individual regions of the catheter assembly 1 that include only individual regions of one or more of the coils 91, 93, 95. When present, the gap G may be used in combination with one or more of the features that affect the performance described herein.

[0059] In one embodiment, all three of the first, second, and third coils 91, 93, 95 may include a plurality of longitudinally spaced gaps G. In addition to increasing the flexibility of the microcatheter 1 while providing the required pushability and torqueability, the gaps G may be used to allow the flow of polymer to wrap around during the assembly / construction process to effectively connect the coils 91, 93, 95 to the outer surface of the liner L. In other embodiments, one or more of the coils 91, 93, 95 may include a gap G. In some embodiments, none of the coils 91, 93, 95 need include a gap G.

[0060] Accordingly, the gap G may constitute a space that defines not only the width but also the depth as described above. For example, if the outer coil 95 includes a gap G and the intermediate coil 93 does not include a gap G that at least partially overlaps the gap G of the outer coil 95, the depth of the gap G of the outer coil 95 is substantially the size / height of the yarns F that make up the outer coil 95. Generally, the depth of the gap G for one coil may be about 0.001 inches, or greater or less than about 0.001 inches, depending on the size or height of the yarns F of each coil.

[0061] In some embodiments, at least two of the coils 91, 93, 95 may have gaps G that overlap at several locations along the coil assembly 1. For example, at least one gap G of the outer coil 95 may overlap at least one gap of the intermediate coil 93. Alternatively, at least one gap G of the intermediate coil 93 may overlap at least one gap G of the inner coil 91. Thus, in this embodiment, the depth of the gap G for two coils may be provided along at least a portion of each overlapping gap G. Generally, the depth of the overlapping gap G between these two coils may be about 0.002 inches, or greater or less than about 0.002 inches, depending on the size or height of the yarn F. There may be portions of two overlapping gaps G and portions of the same two non-overlapping gaps. In this case, the overlapping depth may be about 0.002 inches, or greater or less than about 0.002 inches, and the depth of the non-overlapping gaps of each coil may be about 0.001 inches, or greater or less than about 0.001 inches, depending on the size or height of the yarn F of each coil.

[0062] The first, second, and third coils 91, 93, and 95 may be crimped, particularly to vary the cross-sectional shape of the wire assembly components and the space of the gaps. In some cases, crimping may also control, block, reduce, or eliminate the passage of fluid between adjacent turns of the yarn F. It may also serve to characterize the flow of resin through the gap G during the construction process. The crimped wire may also present a low profile for passing through a patient's vasculature and, accordingly, may reduce the depth of the gap G described herein.

[0063] In some embodiments, all three of the coils 91, 93, 95 may have gaps G that overlap at several locations along the coil assembly 1. For example, at least one gap G of the outer coil 95 may overlap at least one gap of the intermediate coil 93, and these gaps G may overlap at least one gap G of the inner coil 91. Thus, in this embodiment, the depth of the gap G for the three coils may be provided along at least a portion of each of the overlapping gaps G. Generally, if the exemplary yarn also has a thickness of about 0.01 inches in height such that the resulting coils 91, 93, and / or 95 also have a depth or thickness of about 0.01 inches, the depth of the overlapping gaps G of the three coils may be about 0.03 inches, or greater or less than about 0.03 inches, depending on the size or height of the yarn F. There may be portions of the three overlapping gaps G and portions of the same three gaps that do not overlap or overlap with only two coils. In this case, the depth at which the three coils overlap may be about 0.03 inches, or greater or less than about 0.03 inches, depending on the size or height of the yarn F for each coil, the depth at which two coils overlap may be about 0.02 inches, or greater or less than about 0.02 inches, and the depth of the non-overlapping gaps of each coil may be about 0.01 inches, or greater or less than about 0.01 inches.

[0064] When a construction method that utilizes heat (e.g., heat shrinkage or reflow) or the flow of a polymeric material (e.g., compression extrusion) is used, the gap G can allow for the flow of the polymeric material from the outside to the inside of the catheter (e.g., outside of the liner L). When gaps G are provided in adjacent coils 91 or 93 or 95, the gaps may be staggered longitudinally from each other, or alternatively, at least partially overlap and be arranged to provide a path for resin flow during the construction process. See FIG. 8 for an exemplary manufacturing process.

[0065] Each wire F may have an equal width, or the wires F may have unequal widths. A preferred width is about 0.01 inches, but the wire F may be larger or smaller than 0.01 inches. The wire F may be made of the same material throughout the coils 91, 93, and / or 95, and / or the coil assembly 1. Alternatively, two or more materials may form the wire F of the coils 91, 93, 95. As a further alternative, at least a portion of at least one of the coils 91, 93, and / or 95 may include a proximal region of the wire F made of a material different from the material of the wire F in the distal region. As briefly described above, the number and / or the width or radius of the individual wires F in one or more of the coils 91, 93, 95 may be constant or equal along the length of one or more of the coils 91, 93, 95, or may decrease in the distal direction along one or more of the coils 91, 93, 95.

[0066] The wire F forming one or more of the coils 91, 93, and 95 may be swaged to impart work hardening to the wire F and change the cross-sectional shape and the interstitial space of the wire assembly component. In some cases, swaging may control, block, reduce, or eliminate the passage of fluid between the turns of the wire. It may also serve to characterize the flow of resin through the gap G during the construction process. The swaged wire F may also present a low profile for passing through a patient's vasculature and may be used, in particular, to modify the stiffness and / or flexibility characteristics.

[0067] These variables may be used to optimize stiffness, flexibility, pushability, and torque imparting properties. For example, without limitation, a more flexible coil assembly 1 may be provided by providing a wire F of less than about 0.001 inches forming one or more of the coils 91, 93, or 95. Alternatively, the proximal region of one or more of the coils 91, 93, 95 may include a wire F that is wider than the width of the wire F in the distal region of one or more of the coils 91, 93, 95.

[0068] Furthermore, a thread F wound to provide at least one of the coils 91, 93, 95 that includes a material that is harder or more flexible than the material that constitutes the remaining coils 91, 93, 95 may be provided using a harder or more flexible material in a similar manner. Alternatively, at least a portion of at least one of the coils 91, 93, 95 may comprise a harder material that transitions to a less hard, more flexible material along the length of the at least one coil. For example, to provide a more flexible coil assembly 1 in the distal region, a harder material may be used for the thread F in the proximal region of at least one of the coils 91, 93, 95, and a more flexible material may be used for the thread F in the distal region of the coils 91, 93, 95. The selection of the width of the thread F and / or the material including the material of the thread F may be used alone or in combination to achieve a desired balance among rigidity, flexibility, pushability, torque imparting property, and buckling resistance.

[0069] In another embodiment, the flexibility of the thread F may increase distally along the inner liner L. In another embodiment, the rigidity of the thread F may decrease distally, or a section of a harder wire or thread F may be disposed between more flexible threads F. The flexibility or rigidity may vary gradually or abruptly in various embodiments of the present invention.

[0070] The wire F forming one or more of the first, second, and third coils 91, 93, and 95 may have a rounded or flattened (e.g., rectangular) cross-sectional shape. Preferably, the wire F is constructed from stainless steel, although alternative materials such as nitinol, gold, aluminum, silver, and combinations thereof may be used. Examples of suitable materials include 316, 303, 302, 17-4PH, 17-7PH, 18-8, and 304V stainless steel, and / or combinations thereof. In some cases, all of the wire F of one or more of the coils 91, 93, 95 may be the same, and in other cases, different materials may be used for the coils 91, 93, and 95, e.g., the coils may comprise wire F constructed from different materials. In one embodiment, all of the wire F are of the same material, e.g., stainless steel. The individual wire F may initially have a round cross-section, but during the manufacturing process, the wire or wire F may be flattened during construction steps including steps such as collectively swaging the components to provide a cross-sectional shape such as a rectangle.

[0071] Preferably, the first, second, and third coils 91, 93, and 95 are multi-wire coils. In one embodiment, one or more of the first, second, and third coil assemblies 91, 93, and 95 are single filament wire coils consisting of a single wire or wire F wound continuously as described above. One or more of the coils 91, 93, and 95 may be swaged to apply work hardening to the wire and change the cross-sectional shape and the space of the gaps of the wire assembly parts. In some cases, swaging may also control, block, reduce, or eliminate the passage of fluid between the turns of the wire. It may also serve to characterize the flow of resin through the gap G during the construction process. The swaged wire may also exhibit a low profile, i.e., the passage profile (outer diameter) of the microcatheter 1, thereby improving passage through the patient's vasculature.

[0072] The coil assembly 1 and the microcatheter 100 preferably have no braiding in order to provide good torque characteristics in response and to impart axial strength. Surprisingly, it has been found that a non-braided configuration can provide a microcatheter with desirable properties such as torque response, pushability, and flexibility while maintaining overall resistance to buckling. The absence of braiding has been found to provide appropriate mechanical properties while maintaining sufficient resistance to elongation. However, as described above, some embodiments of the microcatheters disclosed herein may include a braid disposed along at least a portion of the inner liner L and / or across one or more of the coils 91, 93, 95 and / or across at least a portion of the length between two or more of the coils 91, 93 and / or 95. In some embodiments, the braid may extend to the distal end of the distal tip T. In other embodiments, the braid, if present, may terminate at a position proximal to the distal end of the distal tip T. In some embodiments, the braid may have a distal end that terminates at a point that is proximal to, distal to, or at the same position as the distal ends of the coils 91, 93, and / or 95.

[0073] More generally, the outer diameter of the catheter body 110 may gradually decrease as it moves from proximal to distal. The taper may be gradual or may include more discrete changes or steps in the outer diameter as it moves longitudinally. For example, by way of non-limitation, the outer diameter may be close to about 0.95 mm near the proximal portion P and close to about 0.71 mm near the tapered portion of the outer surface of the tip portion T.

[0074] FIG. 10 shows a partial cutaway view of an exemplary microcatheter 100, showing an exemplary three - coil structure having an outermost coil 95 and an optional marker band distal to the distal end of the three - coil structure. The marker band is shown proximal to the distal end of the polymeric liner L. However, and without limitation, it may occupy other positions, including extending to the distal end of the liner L. Additionally, the marker material may be incorporated into the inner liner L and / or one or more of the coils 91, 93, 95. The optional marker band or incorporated marker material of FIG. 10 may include a material that enhances visibility under scans such as intravascular ultrasound (IVUS), optical coherence tomography (OCT), or other suitable imaging methods.

[0075] Generally, the inner liner L may preferably extend to the distal end of the distal tip T. However, in other embodiments, the inner liner L may have a distal end proximal to the distal end of the distal tip T.

[0076] FIG. 8 provides an exemplary manufacturing process flow 200 for various embodiments of the present disclosure. In operation 202, a polymeric liner for loading into the coil assembly is prepared. In some embodiments, the coil assembly is obtained pre - manufactured in a three - coil structure as described above. In some such cases, an exemplary set of three coils may be of substantially equal length, and the distal ends of coils 91, 93, and 95 are in a common position.

[0077] In one embodiment, the polymeric inner liner may be inserted into the coil assembly. In another embodiment, the first coil may be wound around the polymeric inner liner, and subsequent coils of the coil assembly may be wound around the first coil, and if a third coil exists, the third coil may be wound around the second coil.

[0078] In operation 206, a marker band or other material may be provided near the distal end of the polymeric liner. In step 208, the extruded article is loaded, and in step 210 a reflow process of the polymer is performed. As described herein, the reflow may have a path through, for example, the coil assembly through a gap to provide a seal against or in contact with the outer surface of the inner polymeric liner.

[0079] In operation 212, the reflowed coating is provided around the outer coil of the coil assembly. Operation 214 is an in-process inspection to ensure that the structure is acceptable so far. Operation 216 includes forming a distal tip structure and attaching it to the inner liner and the coil assembly. Operation 218 forms a proximal hub structure, and operation 220 forms a strain relief structure. Operation 222 is an inspection of the formed hub and strain relief structure, and operation 224 is an overall inspection of the catheter.

[0080] Operation 226 is a coating of the catheter with a hydrophilic material, and operation 228 is a final catheter inspection. In operation 230, the completed microcatheter is packaged, and in operation 232, the packaged microcatheter is sterilized.

[0081] Generally, the inventors have found that the following functional elements in microcatheters commonly used for collateral vessel access and in microcatheters commonly used for retrograde or antegrade access to, for example, a lesion or site of a subject provide improved traversability of the vasculature and lesions.

[0082] Bidirectional rotational ability. The microcatheter is configured to be rotated in at least a first clockwise direction and at least a first counterclockwise direction, and the clockwise rotation and counterclockwise rotation generate substantially the same torque application force at the distal end of the microcatheter. The following torque application force data and ranges have been found to provide improved bidirectional rotational ability and the resulting traversability function.

[0083] For example, in an exemplary microcatheter of the present disclosure, preferably, the torque applying force generated by the first clockwise rotation of the microcatheter for one rotation and the torque applying force generated by the first counterclockwise rotation of the microcatheter for one rotation are each in the range of about 0.08 to about 0.1 ounce force inches.

[0084] Furthermore, in an exemplary microcatheter of the present disclosure, preferably, it provides a torque applying force generated by the first clockwise rotation and a torque applying force generated by the first counterclockwise rotation that are within about 0.02 ounce force inches of each other.

[0085] In addition, in an exemplary microcatheter of the present disclosure, preferably, it provides a torque applying force generated by the second clockwise rotation and a torque applying force generated by the second counterclockwise rotation that are within about 0.02 ounce force inches of each other.

[0086] Also, in an exemplary microcatheter of the present disclosure, preferably, it provides a torque applying force generated by the third clockwise rotation and a torque applying force generated by the third counterclockwise rotation that are within about 0.02 ounce force inches of each other.

[0087] In an exemplary microcatheter of the present disclosure, preferably, it provides a torque applying force generated by the fourth clockwise rotation and a torque applying force generated by the fourth counterclockwise rotation that are within about 0.02 ounce force inches of each other.

[0088] Also, in an exemplary microcatheter of the present disclosure, preferably, it provides a torque applying force generated by the fifth clockwise rotation and a torque applying force generated by the fifth counterclockwise rotation that are within about 0.02 ounce force inches of each other.

[0089] The exemplary microcatheter of the present disclosure further provides a difference in the magnitude of the torque-applying force generated by the first clockwise rotation per revolution, which is in the range of about 0.08 to about 0.1 ounce-force inches, and the torque-applying force generated by the second clockwise rotation per revolution, and the difference in the magnitude of the torque-applying force generated by the first counterclockwise rotation per revolution of the microcatheter and the torque-applying force generated by the second counterclockwise rotation per revolution of the microcatheter is in the range of about 0.08 to about 0.1 ounce-force inches.

[0090] In addition, the exemplary microcatheter of the present disclosure provides a difference in the magnitude of the torque-applying force generated by the second clockwise rotation per revolution of the microcatheter, which is in the range of about 0.08 to about 0.1 ounce-force inches, and the torque-applying force generated by the third clockwise rotation per revolution of the microcatheter, and the difference in the magnitude of the torque-applying force generated by the second counterclockwise rotation per revolution of the microcatheter and the torque-applying force generated by the third counterclockwise rotation per revolution of the microcatheter is in the range of about 0.08 to about 0.1 ounce-force inches.

[0091] Furthermore, the exemplary microcatheter of the present disclosure provides a difference in the magnitude of the torque-applying force generated by the third clockwise rotation per revolution of the microcatheter, which is in the range of about 0.08 to about 0.1 ounce-force inches, and the torque-applying force generated by the fourth clockwise rotation per revolution of the microcatheter, and the difference in the magnitude of the torque-applying force generated by the third counterclockwise rotation per revolution of the microcatheter and the torque-applying force generated by the fourth counterclockwise rotation per revolution of the microcatheter is in the range of about 0.08 to about 0.1 ounce-force inches.

[0092] The exemplary microcatheter of the present disclosure further has a difference in the magnitude of the torque-applying force generated by a fourth clockwise rotation of the microcatheter per revolution and the torque-applying force generated by a fifth clockwise rotation of the microcatheter per revolution in the range of about 0.08 to about 0.1 ounce-force inches, and a difference in the magnitude of the torque-applying force generated by a fourth counterclockwise rotation of the microcatheter per revolution and the torque-applying force generated by a fifth counterclockwise rotation of the microcatheter per revolution in the range of about 0.08 to about 0.1 ounce-force inches.

[0093] In addition, the distal end of the microcatheter of the present disclosure has flexibility that contributes to improved passage characteristics when within a preferred range.

[0094] For example, when the applied force deflects or bends the distal end of the microcatheter of the present invention by a distance of 0 to 2 mm from the longitudinal axis, the preferred range of the gradient of the applied force is from about (y = 0.085x + b) to about (y = 0.13x + b).

[0095] When the applied force deflects or bends the distal end of the microcatheter of the present invention by a distance of 0 to 4 mm from the longitudinal axis, the preferred range of the gradient of the applied force is from about (y = 0.07x + b) to about (y = 0.12x + b).

[0096] When the applied force deflects or bends the distal end of the microcatheter of the present invention by a distance of 0 to 6 mm from the longitudinal axis, the preferred range of the gradient of the applied force is from about (y = 0.08x + b) to about (y = 0.1x + b).

[0097] When the applied force deflects or bends the distal end of the microcatheter of the present invention by a distance of 0 to 8 mm from the longitudinal axis, the preferred range of the gradient of the applied force is from about (y = 0.07x + b) to about (y = 0.09x + b).

[0098] Similarly, the preferred range of force to deflect or bend the distal end of the microcatheter of the present disclosure from the longitudinal axis by 0 mm to 2 mm is from about 0.09 to about 0.130 g / mm.

[0099] The preferred range of force to deflect or bend the distal end of the microcatheter of the present disclosure from the longitudinal axis by 0 mm to 4 mm is from about 0.085 to about 0.12 g / mm.

[0100] The preferred range of force to deflect or bend the distal end of the microcatheter of the present disclosure from the longitudinal axis by 0 mm to 6 mm is from about 0.085 to about 0.1 g / mm.

[0101] The preferred range of force to deflect or bend the distal end of the microcatheter of the present disclosure from the longitudinal axis by 0 mm to 8 mm is from about 0.07 to about 0.09 g / mm.

[0102] Table 1 below provides two non-limiting examples of the microcatheter according to the present disclosure. As described above, microcatheters may generally be used to obtain collateral vessel access as well as other types of vessel access. In some cases, the microcatheters commonly used in retrograde procedures may be the best option for the surgeon, while in other cases, the surgeon may prefer microcatheters commonly used in antegrade procedures. Table 1 provides two exemplary microcatheters of the present disclosure that may be used in retrograde or antegrade procedures.

[0103]

Table 1-1

[0104]

Table 1-2

[0105]

Table 1-3

[0106] Examples and Competing Procedures Example 1 is a bidirectional torque test that measures the torque application forces related to clockwise and counterclockwise rotation of the microcatheter under test.

[0107] Example 2 is a flexure or flexibility test that measures the amount of force applied to deflect or bend the distal end of each microcatheter under test by a distance selected from the longitudinal axis through the microcatheter.

[0108] Tested Microcatheters A summary table of the relevant characteristics of the tested microcatheters is provided in Table 2. Competing devices A and B are currently marketed microcatheters commonly used in retrograde procedures. The comparative microcatheter, which is an exemplary embodiment of the present disclosure, may be used in retrograde procedures, but is not particularly limited to retrograde procedures and may therefore also be used in antegrade procedures.

[0109] [Table 2]

[0110] Example 1 - Bidirectional Torque Test and Comparison with Competing Products Using the test platform and method further described below, a bidirectional torque test was performed on the microcatheter under test. In this test, the torque application forces generated by the microcatheter are compared after one or more rotations in the clockwise and / or counterclockwise directions. Exemplary embodiments of the present disclosure were tested, where the structure of the exemplary embodiments tested is within the description of Tables 1 and 2, and in addition, the selected currently marketed microcatheters under test described in Table 2 were used.

[0111] Mechanism and Method for Torque Application Force Generation Test Referring to FIGS. 9 and 10, the distal tip of the test microcatheter is fastened inside the torque sensor, and the guide wire is inserted into the hub and lumen of the microcatheter through the hub and the microcatheter shaft. The hub is marked so that the rotational position can be identified, facilitating turning or rotating the microcatheter by a predetermined amount, for example, one revolution, either clockwise or counterclockwise. The test method used to generate the torque application force data is as follows. 1. Using the short.014” mandrel within the ID, fasten the distal tip into the torque sensor. Refer to FIG. 8. 2. Insert a guide wire (.014”) or a simulated (.014”) guide wire mandrel through the hub until it contacts the tip mandrel. Refer to FIG. 9. 3. Mark the hub to indicate the rotational position of the zero-degree rotation point. Refer to FIG. 10. 4. Rotate the hub either clockwise or counterclockwise by one revolution or approximately 360 degrees. Confirm that the mandrel moves freely and read the magnitude of the torque application force generated by the rotation from the torque sensor display. 5. Repeat the rotation, for example, in the clockwise direction, for the second, third, etc. rotations until an abnormality occurs or a predetermined number of rotations is reached, and read the magnitude of the torque application force generated by each rotation from the torque sensor display. 6. Repeat the rotation in the other rotational direction, for example, counterclockwise, and read the magnitude of the generated torque application force as indicated by the torque sensor.

[0112] When generating the torque force test data shown in Table 3 below, several samples, for example, 3 - 5 samples, were tested for each microcatheter. The average of each individual test run is provided in Table 3.

[0113] Table 3: Summary of Torque Force Generation Data Summary of the Magnitude Data of the Torque Force of the Microcatheter

[0114]

Table 3

[0115] * CW = clockwise rotation direction, CCW = counterclockwise rotation direction

[0116] Example 2 - Flexibility Test of the Distal Region and Comparison with Competing Products Using the test platform and method further described below, a flexibility test of the 25 cm distal region was performed on the microcatheter under test. In this test, the force required to deflect or bend approximately 25 cm of the distal end region of the catheter under test by a distance defined from the longitudinal axis is compared. Exemplary embodiments of the present disclosure were tested in conjunction with selected currently marketed microcatheters described in Table 2.

[0117] Mechanism and Method for Flexibility Test of the Distal Region The mechanism and method for the flexibility test include a V-block and a central beam as shown in FIGS. 11 and 12. The flexibility of the distal end region defined as approximately 25 cm from the distal end of the microcatheter under test was tested by applying a force to the distal end region in a direction approximately orthogonal to the longitudinal axis of the microcatheter. The applied force required to move, deflect, or bend the distal tip by a predetermined distance, such as approximately 2 mm, 4 mm, 6 mm, and 8 mm, was recorded. The steps of the specific test method are as follows. 1. Place the V-block approximately 25 mm from the central beam. 2. Position the catheter tip so that the proximal end of the tip transition comes under the central beam. 3. Place the central beam within one click from the load reading positioning wheel. 4. Reading of zero distance and zero load 5. Execute the test and deflect the distal tip by approximately 2 mm, 4 mm, 6 mm, and 8 mm. 6. Record the force required to reach those deflection distances.

[0118] When generating the flexibility test data shown in Table 4 below, several samples, for example 3 to 5 samples, were tested for each microcatheter. The average of each individual test run is provided in Table 4.

[0119] Table 4: Summary of Flexibility Data Results of the force of the distal end region flexion test of the microcatheter

[0120]

Table 4

[0121] In addition to the flexion force required to flex or bend the distal tip of each microcatheter under test to a specified flexion distance, namely approximately 2 mm, approximately 4 mm, approximately 6 mm, and approximately 8 mm, as shown in Table 5 below, the gradient of the test data at the specified flexion distance was also calculated. Each gradient in Table 5 is the average of several test runs. A linear equation may be given to each average gradient value. For example, in an exemplary embodiment of 2 mm of flexion, the linear equation of the gradient is y = 0.124x + b. Linear equations with variables for y and the intercept (b) are also possible for the remaining gradient values in Table 5.

[0122] Table 5: Flexibility of the Distal End Region - Gradient Results Gradient Results of the Test Force of the Microcatheter Flexion Test

[0123]

Table 5

[0124] Catheter 100 constructed using the above teachings and findings in various combinations can have a very desirable combination of features that contribute to improved passage through the vasculature and lesions, such as stiffness and axial force transmission, flexibility and torque response, peak following force, flexion force, torsional resistance, and buckling resistance.

[0125] Some exemplary embodiments of the disclosed microcatheters are as follows. Embodiment 1: A microcatheter comprising a proximal end, a distal end, and a length, a polymeric inner liner defining a lumen having an inner diameter, and a coil assembly, the coil assembly comprising a first innermost coil having a proximal end, a distal end, and a length, the first innermost coil comprising one or more filaments wound in a first winding direction around the polymeric inner liner, a second intermediate coil having a proximal end, a distal end, and a length, the second intermediate coil comprising one or more filaments wound in a second winding direction different from the first winding direction around the first innermost coil, a third outermost coil having a proximal end, a distal end, and a length, the third outermost coil comprising one or more filaments wound in a direction different from the second winding direction around the second intermediate coil, wherein the distal end of the third outermost coil is positioned proximal to the distal ends of each of the first innermost coil and the second intermediate coil, wherein the distal ends of the first innermost coil, the second intermediate coil, and the third outermost coil each terminate at the same position, and the microcatheter further comprising a polymeric outer layer surrounding the coil assembly, a distal tip formed from at least one polymer, having a proximal end and a distal end, surrounding the inner liner, the distal tip being operably connected to the polymeric outer layer and the inner liner extending to the distal end of the distal tip, a hub operably connected to the proximal region of the coil assembly, defining a lumen and a proximal inlet to the lumen in fluid communication therewith, the proximal inlet defined by the hub and the lumen defined by the hub each being in fluid communication with the lumen defined by the inner liner, a microcatheter.

[0126] Embodiment 2: The microcatheter of Embodiment 1, wherein the distal tip further surrounds the proximal portion of the coil assembly.

[0127] Embodiment 3: The microcatheter of Embodiment 1, wherein at least a part of the filaments of at least a part of the coil assembly is crimped to reduce the width and / or height of the crimped filaments.

[0128] Embodiment 4: The microcatheter of Embodiment 1, wherein the microcatheter has an outer diameter that decreases in the distal direction.

[0129] Embodiment 5: The microcatheter of Embodiment 1, wherein the microcatheter comprises a proximal section, a transition section, and a distal section, and the outer diameter of the distal section is about 2.1F.

[0130] Embodiment 6: The microcatheter of Embodiment 1, wherein the length of the first innermost coil is longer than the length of the third outermost coil.

[0131] Embodiment 7: The microcatheter of Embodiment 1, wherein the length of the second intermediate coil is longer than the length of the third outermost coil.

[0132] Embodiment 8: The microcatheter of Embodiment 1, wherein at least one of the first innermost coil, the second intermediate coil, and the third outermost coil is wound in a spiral configuration.

[0133] Embodiment 9: The microcatheter of Embodiment 1, wherein the microcatheter is configured to rotate bidirectionally and resist extension and shortening during rotation.

[0134] Embodiment 10: The microcatheter of Embodiment 1, wherein each distal end of the first innermost coil, the second intermediate coil, and the third outermost coil is located less than 5 mm from the distal end of the distal tip.

[0135] Embodiment 11: The micro catheter of Embodiment 1, wherein the distal ends of the first innermost coil, the second intermediate coil, and the third outermost coil are each less than 2 mm from the distal end of the distal tip.

[0136] Embodiment 12: The micro catheter of Embodiment 1, wherein the distal ends of the first innermost coil, the second intermediate coil, and the third outermost coil are each located approximately 1 mm from the distal end of the distal tip.

[0137] Embodiment 13: The micro catheter of Embodiment 1, wherein the distal ends of the first innermost coil, the second intermediate coil, and the third outermost coil are each located less than 1 mm from the distal end of the distal tip.

[0138] Embodiment 14: The micro catheter of Embodiment 1, wherein the outer layer of the polymer comprises a section adjacent to the distal tip having a Shore hardness of 35D or less and a length of approximately 15 cm.

[0139] Embodiment 15: The micro catheter of Embodiment 1, wherein the distal tip comprises a distal region having a tapered shape that decreases in the distal direction.

[0140] Embodiment 16: The micro catheter of Embodiment 1, wherein the distal tip comprises a distal region having an outer diameter that decreases in the distal direction.

[0141] Embodiment 17: The micro catheter of Embodiment 1, further comprising a polymer outer layer whose Shore hardness decreases in the distal direction.

[0142] Embodiment 18: The micro catheter of Embodiment 1, wherein at least one of the first innermost coil, the second intermediate coil, and the third outermost coil comprises at least two groups of two or more windings made of one or more threads, and there is no gap between adjacent windings among at least two groups of two or more windings made of one or more threads. There is a gap between adjacent groups of windings.

[0143] Embodiment 19: The microcatheter of Embodiment 18, wherein each group of windings comprises about 6 to 24 windings.

[0144] Embodiment 20: The microcatheter of Embodiment 18, wherein each group of windings comprises about 10 to about 20 windings.

[0145] Embodiment 21: The microcatheter of Embodiment 18, wherein each group of windings comprises 18 windings.

[0146] Embodiment 22: The microcatheter of Embodiment 18, wherein each group of windings comprises an equal number of windings.

[0147] Embodiment 23: The microcatheter of Embodiment 18, wherein the number of windings within each group of windings decreases distally along at least a portion of the length of at least one of the first innermost coil, the second intermediate coil, and the third outermost coil.

[0148] Embodiment 24: The microcatheter of Embodiment 18, wherein one or more wires have a width, and the gap between adjacent groups is approximately equal to the width of one or more wires.

[0149] Embodiment 25: The microcatheter of Embodiment 18, wherein the gap between adjacent groups is 0.01 inch or more.

[0150] Embodiment 26: The microcatheter of Embodiment 18, wherein the gap between adjacent groups is less than 0.01 inch.

[0151] Embodiment 27: The microcatheter of Embodiment 18, wherein the width of the gap between adjacent groups of windings increases distally along at least a portion of the length of at least one of the first innermost coil, the second intermediate coil, and the third outermost coil.

[0152] Embodiment 28: The microcatheter of Embodiment 1, wherein the first, second, and third coils are constructed from the same material.

[0153] Embodiment 29: The microcatheter of Embodiment 1, wherein the first, second, and third coils are constructed from different materials.

[0154] Embodiment 30: The microcatheter of Embodiment 1, wherein the microcatheter is an antegrade catheter or a retrograde catheter.

[0155] Embodiment 31: The microcatheter of claim 1, wherein the microcatheter does not comprise a braid.

[0156] Embodiment 32: The microcatheter of Embodiment 1, comprising one or more of Embodiments 2-31.

[0157] Without departing from the scope of the present invention, further deflections and improvements may additionally be made to the devices and methods disclosed herein. Accordingly, the present invention is not intended to be limited except as by the appended claims. The description of different features as combinations of materials and shapes is for the purpose of highlighting various functional aspects, and does not necessarily imply that such features must be implemented in the materials and shapes described for such components. Rather, the functions associated with one or more shapes and materials may be performed by separate or different shapes or materials.

Description of Reference Numerals

[0158] 1 Coil assembly 3 Regions Regions and parts 4, 5, 6, 7, 8, 9, 23 12 Strain relief 13 Hub 14 Proximal region, section 15 Intermediate region, transition region, section 16 Distal region, section 20 Outlet 21 Inner diameter 25 Outer diameter 91, 93, 95 Coils 97 Yarn group 100 Microcatheter 110 Body T Distal tip, tip portion L Liner AX Longitudinal axis P Proximal portion D Distal portion F Yarn G Gap

Claims

1. A polymeric inner liner having a proximal end, a distal end, and a length, defining a lumen having an inner diameter, and a coil assembly surrounding a portion of the length of the polymeric inner liner, A microcatheter comprising: the microcatheter is configured to rotate in a clockwise and counterclockwise direction to generate a torque-applying force at the distal end of the microcatheter, wherein the torque-applying force generated by a first clockwise rotation of one revolution of the microcatheter and the torque-applying force generated by a first counterclockwise rotation of one revolution of the microcatheter are each in the range of about 0.08 to about 0.1 ounce force-inch.

2. The microcatheter according to claim 1, wherein the polymeric inner liner extends distally to the distal end of the microcatheter.

3. The coil assembly includes a first inner coil surrounding at least a portion of the length of the polymeric inner liner, a second intermediate coil surrounding at least a portion of the length of the first inner coil, and a third outermost coil surrounding at least a portion of the length of the second intermediate coil, and the coil assembly has a distal end located proximal to the distal end of the microcatheter. The microcatheter according to claim 1 or 2.

4. The microcatheter according to any one of claims 1 to 3, wherein the torque-applying force generated by the first clockwise rotation and the torque-applying force generated by the first counterclockwise rotation are within about 0.02 ounce force-inch of each other.

5. The torque applying force generated by the second clockwise rotation of the microcatheter for one rotation and the torque applying force generated by the second counterclockwise rotation of the microcatheter are within about 0.02 ounce force inches of each other. The microcatheter according to any one of claims 1 to 4.

6. The torque applying force generated by the third clockwise rotation of the microcatheter for one rotation and the torque applying force generated by the third counterclockwise rotation of the microcatheter for one rotation are within about 0.02 ounce force inches of each other. The microcatheter according to any one of claims 1 to 5.

7. The torque applying force generated by the fourth clockwise rotation of the microcatheter for one rotation and the torque applying force generated by the fourth counterclockwise rotation of the microcatheter for one rotation are within about 0.02 ounce force inches of each other. The microcatheter according to any one of claims 1 to 6.

8. The torque applying force generated by the fifth clockwise rotation of the microcatheter for one rotation and the torque applying force generated by the fifth counterclockwise rotation of the microcatheter for one rotation are within about 0.02 ounce force inches of each other. The microcatheter according to any one of claims 1 to 7.

9. The microcatheter is configured to be used for retrograde access to an internal location of a target vasculature. The microcatheter according to any one of claims 1 to 8.

10. The microcatheter is configured to be used for antegrade access to an internal location of a target vasculature. The microcatheter according to any one of claims 1 to 9.

11. A polymeric inner liner having a proximal end, a distal end, and a length, and defining a lumen having an inner diameter. A coil assembly surrounding a portion of the length of the polymeric inner liner, A microcatheter comprising: The microcatheter is configured to rotate in a clockwise and counterclockwise direction to generate a torque applying force at a distal end of the microcatheter, The difference in magnitude between the torque applying force generated by a first clockwise rotation of one revolution of the microcatheter and the torque applying force generated by a second clockwise rotation of one revolution of the microcatheter is in the range of about 0.08 to about 0.1 ounce force inches, The difference in magnitude between the torque applying force generated by a first counterclockwise rotation of one revolution of the microcatheter and the torque applying force generated by a second counterclockwise rotation of one revolution of the microcatheter is in the range of about 0.08 to about 0.1 ounce force inches.

12. The microcatheter according to claim 11, wherein the polymeric inner liner extends distally to a distal end of the microcatheter.

13. The coil assembly includes a first inner coil surrounding at least a portion of the length of the polymeric inner liner, a second intermediate coil surrounding at least a portion of the length of the first inner coil, and a third outermost coil surrounding at least a portion of the length of the second intermediate coil, and the coil assembly has a distal end located proximal to the distal end of the microcatheter. The microcatheter according to claim 11 or 12.

14. The difference in magnitude between the torque applying force generated by the second clockwise rotation of one revolution of the microcatheter and the torque applying force generated by a third clockwise rotation of one revolution of the microcatheter is in the range of about 0.08 to about 0.1 ounce force inches, The difference in magnitude between the torque applying force generated by the second counterclockwise rotation and the torque applying force generated by the third counterclockwise rotation is in the range of about 0.08 to about 0.1 ounce force inches, the microcatheter according to any one of claims 11 to 13.

15. The difference in magnitude between the torque applying force generated by the third clockwise rotation for one rotation of the microcatheter and the torque applying force generated by the fourth clockwise rotation for one rotation of the microcatheter is in the range of about 0.08 to about 0.1 ounce force inches, The difference in magnitude between the torque applying force generated by the third counterclockwise rotation and the torque applying force generated by the fourth counterclockwise rotation is in the range of about 0.08 to about 0.1 ounce force inches, the microcatheter according to any one of claims 11 to 14.

16. The difference in magnitude between the torque applying force generated by the fourth clockwise rotation for one rotation and the torque applying force generated by the fifth clockwise rotation for one rotation is in the range of about 0.08 to about 0.1 ounce force inches, The difference in magnitude between the torque applying force generated by the fourth counterclockwise rotation for one rotation of the microcatheter and the torque applying force generated by the fifth counterclockwise rotation for one rotation of the microcatheter is in the range of about 0.08 to about 0.1 ounce force inches, the microcatheter according to any one of claims 11 to 15.

17. The microcatheter is configured to be used for retrograde access to an internal site of a target blood vessel, the microcatheter according to any one of claims 11 to 16.

18. The microcatheter is configured to be used for antegrade access to an internal site of a target blood vessel, the microcatheter according to any one of claims 11 to 17.

19. A polymeric inner liner having a proximal end, a distal end, and a length and defining a lumen having an inner diameter, A coil assembly surrounding a portion of the length of the polymeric inner liner, A microcatheter comprising: The microcatheter is configured to rotate in a clockwise and counterclockwise direction to generate a torque application force at the distal end of the microcatheter, Over a plurality of clockwise and counterclockwise rotations, each rotation constituting one rotation of the first clockwise rotation of the microcatheter generates a torque application force in the range of about 0.08 to about 0.1 ounce force inches, The first counterclockwise rotation for one rotation of the microcatheter generates a torque application force in the range of about 0.08 to about 0.1 ounce force inches, For each subsequent rotation of the plurality of clockwise rotations, a torque application force in the range of about 0.08 to about 0.1 ounce force inches is generated, For each subsequent rotation of the plurality of counterclockwise rotations, a torque application force in the range of about 0.08 to about 0.1 ounce force inches is generated, a microcatheter.

20. The microcatheter according to claim 19, wherein the polymeric inner liner extends distally to the distal end of the microcatheter.

21. The coil assembly includes a first inner coil surrounding at least a portion of the length of the polymeric inner liner, a second intermediate coil surrounding at least a portion of the length of the first inner coil, and a third outermost coil surrounding at least a portion of the length of the second intermediate coil, and the coil assembly has a distal end located proximal to the distal end of the microcatheter. The microcatheter according to claim 19 or 20.

22. The microcatheter according to any one of claims 19 to 21, wherein the microcatheter is configured to be used for retrograde access to a target intravascular location.

23. The microcatheter according to any one of claims 19 to 22, configured to be used for performing anterograde access to a target vascular internal site.

24. A polymer inner liner having a proximal end, a distal end, and a length, defining a lumen having an inner diameter, and A coil assembly surrounding a part of the length of the polymer inner liner, and A microcatheter comprising: A force is required to deflect or bend the distal tip of the distal end region constituting 25 cm in length of the microcatheter from a distance of 0 mm to a distance of 2 mm from the longitudinal axis, The force generates a gradient section having a gradient in the range of about (y = 0.085x + b) to about (y = 0.13x + b), a microcatheter.

25. The microcatheter according to claim 24, wherein the polymer inner liner extends distally to the distal end of the microcatheter.

26. The coil assembly includes a first inner coil surrounding at least a part of the length of the polymer inner liner, a second intermediate coil surrounding at least a part of the length of the first inner coil, and a third outermost coil surrounding at least a part of the length of the second intermediate coil, and the coil assembly has a distal end located proximal to the distal end of the microcatheter. The microcatheter according to claim 24 or 25.

27. A force is required to deflect or bend the distal end region of the microcatheter from a distance of 0 mm to a distance of 4 mm from the longitudinal axis, The applied force generates a gradient section having a gradient in the range of about (y = 0.07x + b) to about (y = 0.12x + b). The microcatheter according to any one of claims 24 to 26.

28. A force is required to deflect or bend the distal tip of the microcatheter from a distance of 0 mm to a distance of 6 mm from the longitudinal axis. The microcatheter according to any one of claims 24 to 27, wherein the applied force generates a gradient section having a gradient in the range of about (y = 0.08x + b) to about (y = 0.1x + b).

29. Further comprising that a force is required to deflect or bend the distal tip of the microcatheter by a distance of 8 mm from the longitudinal axis. The microcatheter according to any one of claims 24 to 28, wherein the applied force generates a gradient section having a gradient in the range of about (y = 0.07x + b) to about (y = 0.09x + b).

30. A polymeric inner liner having a proximal end, a distal end, and a length, and defining a lumen having an inner diameter. A coil assembly surrounding a portion of the length of the polymeric inner liner. A microcatheter comprising: The microcatheter, wherein the applied force required to deflect or bend the distal tip of the distal end region of the microcatheter having a length of 25 cm by a distance of 2 mm from the longitudinal axis is in the range of about 0.09 to about 0.130 g / mm.

31. The microcatheter according to claim 30, wherein the applied force required to deflect or bend the distal tip of the microcatheter by a distance of 4 mm from the longitudinal axis is in the range of about 0.085 to about 0.12 g / mm.

32. The microcatheter according to claim 30 or 31, wherein the applied force required to deflect or bend the distal tip of the microcatheter by a distance of 6 mm from the longitudinal axis is in the range of about 0.085 to about 0.10 g / mm.

33. The force applied to deflect or bend the distal tip of the microcatheter by a distance of 8 mm from the longitudinal axis is in the range of about 0.07 to about 0.09 g / mm, the microcatheter according to any one of claims 30 to 32.

34. The polymeric inner liner extends distally to the distal end of the microcatheter, the microcatheter according to any one of claims 30 to 33.

35. The coil assembly includes a first inner coil surrounding at least a portion of the length of the polymeric inner liner, a second intermediate coil surrounding at least a portion of the length of the first inner coil, and a third outermost coil surrounding at least a portion of the length of the second intermediate coil, the coil assembly having a distal end located proximal to the distal end of the microcatheter, the microcatheter according to any one of claims 30 to 34.

36. The microcatheter is configured to be used for retrograde access to an internal location of a target vasculature, the microcatheter according to any one of claims 30 to 35.

37. The microcatheter is configured to be used for antegrade access to an internal location of a target vasculature, the microcatheter according to any one of claims 30 to 36.

38. A polymeric inner liner having a proximal end, a distal end, and a length, defining a lumen having an inner diameter, and An unbraided coil assembly including a first inner coil surrounding at least a portion of the length of the polymeric inner liner, a second intermediate coil surrounding the first inner coil, and a third outermost coil surrounding the second intermediate coil, and An unbraided microcatheter comprising: The inner liner extends distally to the distal end of the microcatheter, An unbraided microcatheter, wherein the unbraided coil assembly has a distal end located proximally from the distal end of the microcatheter.

39. The microcatheter according to claim 38, wherein the distal end of the unbraided coil assembly is located 1 mm from the distal end of the microcatheter.

40. The microcatheter according to claim 38 or 39, wherein at least one of the first innermost coil, the second intermediate coil, and the third outermost coil comprises at least two groups of adjacent wires or threads defined by gaps between the groups of two or more wires or threads.

41. The microcatheter according to claim 40, wherein at least some of the at least two groups of wires or threads include from about 6 to about 24 wires or threads.

42. The microcatheter according to claim 40, wherein at least some of the at least two groups of wires or threads include from about 10 to about 20 wires or threads.

43. The microcatheter according to claim 40, wherein at least some of the at least two groups of wires or threads include 18 wires or threads.

44. The microcatheter according to any one of claims 38 to 43, wherein the microcatheter is configured to be used for retrograde access to an internal site of a target vasculature.

45. The microcatheter according to any one of claims 38 to 44, wherein the microcatheter is configured to be used for antegrade access to an internal site of a target vasculature.

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