Low friction and flexible catheter liner

Abstract

A catheter and method for manufacturing a catheter having an inner layer comprising a polyolefin-based or polyethylene-based thermoplastic elastomer material, an outer layer, and a tie layer disposed between the inner layer and the outer layer. The tie layer is a low durometer polymer. The thermoplastic elastomer material comprises at least one of a polyolefin-based thermoplastic elastomer and, in one embodiment, a polyethylene-based thermoplastic elastomer. The tie layer comprises maleic anhydride grafted linear low density polyethylene (LLDPE).

Description

[Technical field]

[0001] The present invention relates generally to a catheter with a low friction, flexible liner.

[0002] [Citation to Related Applications] This application is a claim of U.S. Provisional Patent Application No. 63 / 285,428, filed December 2, 2021, the disclosure of which is incorporated by reference in its entirety. [Background technology]

[0003] Existing PTFE catheter liners have low friction properties that allow for the delivery of an implant or device while allowing for low friction passage of a coaxial inner catheter. Nevertheless, many existing PTFE catheter liners are too stiff for some applications, and there is a need for more flexible catheter liners that maintain or improve on the low friction properties of existing PTFE liners. Summary of the Invention

[0004] These needs are met to a large extent by the disclosed subject catheter having an inner layer made of a thermoplastic elastomeric material, an outer layer, and a tie layer disposed between the inner and outer layers, the tie layer being made of a low durometer polymer.

[0005] In a first embodiment of the invention, the catheter has an inner layer of a thermoplastic elastomer material, an outer layer, and a tie layer disposed between the inner layer and the outer layer, the tie layer being comprised of a low durometer polymer. The thermoplastic elastomer material comprises at least one polyolefin-based thermoplastic elastomer. The thermoplastic elastomer material may comprise at least one polyethylene-based thermoplastic elastomer. The tie layer may comprise linear low density polyethylene grafted with maleic anhydride. A reinforcement may be disposed between the inner layer and the outer layer. The reinforcement may be embedded within the tie layer. The reinforcement may terminate at a distance from the distal end point of the catheter. The outer layer may have a first section and a second section, the stiffness of the first section being different from the stiffness of the second section. The tie layer may comprise a first tie layer and a second tie layer. In another embodiment, the inner layer includes a first inner layer disposed on a distal portion of the catheter, the first inner layer being made of a thermoplastic elastomer, and the inner layer further includes a second inner layer disposed on a proximal portion of the catheter proximal to the first inner layer, the second inner layer being made of PTFE. In one embodiment, the inner layer is disposed only on the distal portion of the catheter. In another embodiment, the inner layer is disposed along the entire length of the catheter.

[0006] In one embodiment of the invention, the catheter has an inner layer comprising a polyolefin or polyethylene-based thermoplastic elastomer material, an outer layer, and a tie layer between the inner and outer layers, the tie layer being comprised of a low durometer polymer. The inner layer may include one or more lubricants. The tie layer may be comprised of maleic anhydride grafted linear low density polyethylene (LLDPE). The tie layer may be comprised of maleic anhydride modified low density polyethylene (LDPE). The tie layer may be comprised of maleic anhydride modified ethylene vinyl acetate (EVA).

[0007] The catheter may further include a reinforcement material disposed between the inner layer and the outer layer. The reinforcement material may include a coil wire wound circumferentially around the longitudinal axis of the catheter. The reinforcement material may include multiple filamentary coil wires wound circumferentially around the longitudinal axis of the catheter. The reinforcement material may be a braided design wire pattern interwoven circumferentially around the longitudinal axis of the catheter. The braid design may include a density or pix per inch variation along the length of the braid design. The braid design may have a constant density along the length of the braid design. The braid design may include a bottom 1 top 1 bottom 1, bottom 2 top 2 bottom 2, or bottom 1 top 2 bottom 2 pattern. The braid design may include 8, 16, or 32 individual strands, or any number of individual strands. The reinforcement material may include a round, rectangular, or oval geometric shape. The reinforcement may include at least one of Steel, Nitinol, Tungsten, non-metallic monofilament, fiber bundle, Aramid, polymer, Nylon, or LCP. The reinforcement may include a circumferential reinforcement between the inner layer and the outer layer, and a longitudinal reinforcement extending along the longitudinal axis of the catheter. The longitudinal reinforcement may include at least one of Steel, Nitinol, Tungsten, non-metallic monofilament, fiber bundle, Aramid, polymer, Nylon, or LCP. The longitudinal reinforcement may include one, two, three, four, or more longitudinal reinforcements. The longitudinal reinforcement may include a plurality of longitudinal reinforcements symmetrically arranged about a central longitudinal axis of the catheter. The longitudinal reinforcement may include a plurality of longitudinal reinforcements biased to one side of the catheter. The longitudinal stiffener may include a plurality of longitudinal stiffeners randomly arranged about a central longitudinal axis of the catheter, the longitudinal stiffener may include a plurality of longitudinal stiffeners extending along the entire length of the catheter, or the longitudinal stiffener may include a plurality of longitudinal stiffeners extending along only a partial length of the catheter.The longitudinal stiffener may include a plurality of longitudinal stiffeners, each of equal length. The longitudinal stiffener may include a plurality of longitudinal stiffeners, at least two of the plurality of longitudinal stiffeners having different relative lengths. The longitudinal stiffener may be interwoven with the circumferential stiffener. The longitudinal stiffener may not be interwoven with the circumferential stiffener. The longitudinal stiffener may be disposed above, below or between the circumferential stiffener, or between the inner and outer layers. The longitudinal stiffener may be embedded within a bonding layer. The longitudinal stiffener may be disposed above or below the bonding layer. The longitudinal stiffener may be bonded, welded or otherwise attached to the circumferential stiffener. The coil may be disposed above the braid pattern. The coil may be disposed below the braid pattern. The coil wire may include a first coil reinforcement and a second coil reinforcement disposed over the first coil reinforcement. The second coil reinforcement may be wound in a direction opposite to the direction of winding of the first coil reinforcement. The braid design may include a first braided reinforcement and a second coil reinforcement disposed over the first braided reinforcement. The second braided reinforcement may be comprised of a material different from the material comprising the first braided reinforcement. The second braided reinforcement may be comprised of a geometry different from the geometry comprising the first braided reinforcement. The second braided reinforcement may be comprised of a reinforcement pattern different from the reinforcement pattern comprising the first braided reinforcement.

[0008] The reinforcement may be embedded within the tie layer. The tie layer may be located above and below the reinforcement. The tie layer may be located between the braided reinforcement and the coil reinforcement. The tie layer may be located between any of the reinforcement layers.

[0009] The reinforcement may terminate at a distance from the distal end point of the catheter. The outer layer may have a first section and a second section, and the stiffness of the first section may be different from the stiffness of the second section. The trackability of the first section may be better than the trackability of the second section. The tie layer may include a first tie layer and a second tie layer. One or more of the inner layer, tie layer, or outer layer may be crosslinked using E-beam. The inner layer may include a first inner layer on the distal portion of the catheter and made of a thermoplastic elastomer, and a second inner layer on the proximal portion of the catheter proximal to the first inner layer, and the second inner layer may be made of PTFE. The inner layer may be only on the distal portion of the catheter. The inner layer may be disposed on the entire length of the catheter.

[0010] The catheter can have a catheter distal end, which can comprise a radiopaque tip. The radiopaque tip can comprise a polymer containing one or more additives of tungsten, barium sulfate, bismuth subcarbonate, or bismuth oxychloride. The radiopaque tip can comprise a split marker band.

[0011] Various additional features and advantages of the present invention will become apparent to those skilled in the art upon review of the following detailed description of illustrative embodiments which proceeds in conjunction with the accompanying drawings.

[0012] The following detailed description will be better understood when read in conjunction with the accompanying drawings, in which there is shown, by way of example only, embodiments of the invention not limited to the specific elements and instrumentalities disclosed. [Brief description of the drawings]

[0013] [Figure 1A] 1 illustrates a catheter according to aspects of the present invention. [Figure 1B] FIG. 1B is a cross-sectional view of the catheter of FIG. 1A taken along line A-A. [Figure 1C] FIG. 1B shows a Luer hub of the catheter of FIG. 1A. [Diagram 2] FIG. 1B is an enlarged cross-sectional view of the enclosed portion B of the catheter of FIG. 1A. [Diagram 3] 3A to 3C are diagrams showing a process for assembling the catheter shown in FIGS. 1A to 2. [Figure 4A] FIG. 2 is a diagram of another catheter according to aspects of the invention. [Figure 4B] 4B is a cross-sectional view of the catheter of FIG. 4A taken along line CC. [Diagram 5] 4C shows a process for assembling the catheter shown in FIG. 4A and FIG. 4B. [Figure 6A] FIG. 2 is a diagram of another catheter according to aspects of the invention. [Figure 6B] FIG. 6B is a cross-sectional view of the catheter of FIG. 6A taken along line D-D. [Figure 6C] FIG. 6C is an enlarged view of the boxed portion DB of FIG. 6B. [Figure 7] 6A to 6C show a process for assembling the catheter shown in FIG. [Figure 8] 1A-1D illustrate a process for assembling a catheter according to aspects of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Many existing catheters utilize PTFE catheter liners. One reason for using PTFE as a catheter liner is to provide low friction to allow for the delivery of implants or instruments while allowing low friction passage of a coaxial inner catheter. Another reason for using PTFE as a catheter liner is that it is a heat resistant material that lends itself well to thermal lamination of outer materials when the PTFE surface is activated by etching or other means. However, PTFE is a relatively stiff material with a Shore D hardness of 40-60, which means that catheter flexibility is limited by the stiffness of PTFE. Thus, for example in neurovascular applications, there is a need for a variation or complement of a PTFE catheter liner that has both a flexible distal end and low friction on the inner surface to allow for the removal of blood clots while facilitating coaxial advancement within the catheter.

[0015] The present invention addresses the need for an alternative or complementary PTFE catheter liner by providing a catheter liner with a flexible and low friction distal end. The catheter may have a distal liner made of a thermoplastic elastomer material, such as a polyethylene-based thermoplastic elastomer material (e.g., Topas). A catheter with a liner made of a polyethylene-based thermoplastic elastomer material has lower friction and increased flexibility compared to catheters that use primarily PTFE liners. Aspects of the present invention also relate to catheters that utilize a low durometer polymer (e.g., Orevac) in a polyethylene-based thermoplastic elastomer liner. The low durometer polymer can improve adhesion and / or bonding between the polyethylene-based thermoplastic elastomer liner and an outer material (e.g., PEBA). The polyethylene-based thermoplastic elastomer liner combined with a low durometer polymer can achieve a fully laminated catheter composite with lower friction and increased flexibility compared to a PTFE catheter liner. Such liners may improve surgical success by providing access to the MCA, M1 and M2 arteries for treating and removing blockages resulting from ischemic stroke, for example. These and other aspects of the invention are described below with reference to the drawings, in which like reference numerals may refer to like structure.

[0016] 1A-1C show a catheter 100 in accordance with aspects of the present invention. The catheter can have a distal section 102, a proximal section 104, and a luer hub 106. FIG. 2 is an enlarged view of region B of the catheter distal section 102 of the catheter 100. The distal section 102 can include an inner layer 108, a tie layer 110, a distal outer layer 112, a proximal outer layer 114, and a stiffener 116, which in embodiments can include a wire, braid, and / or coil. The inner layer 108 can be made of a material such as a low durometer polyolefin-based thermoplastic elastomer or a polyethylene-based thermoplastic elastomer. In embodiments, the inner layer 108 may include a lubricant (e.g., Propel™ available from Foster Corporation or Mobilize available from Compounding Solutions) in a polyolefin-based thermoplastic elastomer. The lubricant may be set in place, i.e., the lubricant will not shed. In embodiments, the inner layer 108 may extend the entire length of the catheter 10. Alternatively, the inner layer 108 may extend a partial length of the catheter 100, such as extending only to the distal section 102 and not to the proximal section 104. The inner layer 108 may be surrounded by a tie layer 110, which may promote adhesion between two typically incompatible materials. The tie layer 110 may be made of a low durometer (e.g., a Shore D hardness of 60 or less, including 56, 30 or less) polymer. In embodiments, the tie layer 110 may comprise a maleic anhydride grafted linear low density polyethylene (LLDPE), such as Orevac® and / or ReZilok Rx. In embodiments, the tie layer 110 may comprise a maleic anhydride modified low density polyethylene (LDPE). In embodiments, the tie layer 110 may comprise a maleic anhydride modified ethylene vinyl acetate (EVA).In embodiments, the bonding layer 110 may include other materials as described, for example, in EP 0873759 A2, U.S. 6165166 A, and U.S. 6464683 B1, which are incorporated by reference in their entireties. The inner layer 108 may have an undulating inner surface profile. The undulating inner surface profile may have low points and high points. The undulating inner surface profile may reduce contact / friction between the inner layer 108 and, for example, an implant or clot. In embodiments, one or more of the inner layer 108, bonding layer 110, distal outer layer 112, or proximal outer layer 114 may be crosslinked using E-beam, which may improve adhesion between the layers.

[0017] In various embodiments, the distal outer layer 112 and / or the proximal outer layer 114 may be a polar material, i.e., thermally bondable to other polar surfaces, such as polyamides, PEBA (polyether block amides), various families of polyurethane elastomers, and / or polyether-based elastomers (Hytrel®).

[0018] In embodiments, the reinforcement 116 may be encapsulated within the wall of the catheter 100 (e.g., the bonding layer 110). The reinforcement 116 may be comprised of a reinforcing framework, which may be a wire, braid, and / or coil. The reinforcement 116 may include longitudinal support elements and / or other reinforcing components. In embodiments, the reinforcement 116 may be disposed on the bonding layer 110. In embodiments, the reinforcement 116 may be embedded within the bonding layer 110. In embodiments, the bonding layer 110 may be disposed above and / or below the reinforcement 116. In embodiments, the bonding layer 110 may be disposed above and / or below the reinforcement 116 and may be disposed between any of the reinforcement layers described herein. In embodiments, the bonding layer 110 may be disposed above and / or below the stiffeners 116, and may be disposed between any of the braid and / or coil stiffeners described herein.

[0019] In embodiments, the stiffener 116 may be a single coil wire wound circumferentially about the longitudinal axis of the catheter 100. In embodiments, the stiffener 116 may include multiple filamentary coil wires wound circumferentially about the longitudinal axis of the catheter 100. In embodiments, the stiffener 116 may include a braided design of a circumferential wire pattern about the longitudinal axis of the catheter 100. The braided design may include variations in its density or pix per inch throughout its length. The braided design may have a constant density along its length. The braided design may be under 1 over 1 under 1, under 2 over 2 under 2, or over 2 under 2 under 2, or various other interwoven strand patterns. The braided design pattern may be formed of 8, 16, 32, or any number of individual strands. In embodiments, the stiffener 116 may have a round, rectangular, or oval geometric shape. In embodiments, the stiffener 116 may be comprised of steel, nitinol, tungsten, non-metallic monofilaments, or fiber bundles made from aramid or polymers such as nylon or LCP.

[0020] In embodiments, the reinforcements 116 may be circumferential between layers of the catheter 100 and may be augmented with longitudinal reinforcements. The longitudinal reinforcement material may be made of steel, nitinol, tungsten, non-metallic monofilaments, or fiber bundles made from polymers such as aramid or, for example, nylon or LCP. There may be one, two, three, four, or any number of longitudinal reinforcements. The longitudinal reinforcements may be symmetrically arranged around the cross section of the catheter 100, biased to one side, or randomly arranged along or over the entire length of the catheter 100, or the individual longitudinal reinforcements may have individual lengths that differ from one another. The longitudinal reinforcements may be interwoven with the circumferential reinforcements. Alternatively, the longitudinal reinforcements may not be interwoven with the circumferential reinforcements. The longitudinal reinforcements may be located above, below, or between the circumferential reinforcements, or between the inner layer 112 and the outer layer 114. The longitudinal reinforcements may be embedded within the bonding layer 110. The longitudinal reinforcements may be located above or below the bonding layer 110. The longitudinal reinforcements may be bonded, welded, or otherwise attached to the circumferential reinforcements.

[0021] In various embodiments, the reinforcement 116 may include any of the coil reinforcements described above and any of the braid patterns described above, where the coil reinforcement may be disposed over the braid pattern or vice versa.

[0022] In embodiments, the stiffener 116 may include a first coil stiffener and a second coil stiffener, the second coil stiffener may be disposed over the first coil stiffener, and the second coil stiffener may be wound in an opposite direction to the direction in which the first coil stiffener was wound.

[0023] In embodiments, the stiffener 116 can include a first braid stiffener and a second braid stiffener, such as any of the braid designs described above. The second braid stiffener can be disposed over the first braid stiffener. The second braid stiffener can have a different stiffening material and / or stiffening geometry and / or stiffening pattern than the first braid stiffener.

[0024] In embodiments, the catheter 100 may have a catheter distal end that may include a radiopaque tip. The radiopaque tip may include a polymer that may include one or more of the following additives: tungsten, barium sulfate, bismuth subcarbonate, or bismuth oxychloride. The radiopaque tip may have a split marker band that allows the distal end to expand circumferentially when the catheter 100 is used as a thrombectomy / aspiration catheter.

[0025] 3 illustrates a process 300 for manufacturing a catheter, such as catheter 100. In process 300, in step 301, an inner liner may be applied to a mandrel. In embodiments, the inner liner may consist of an inner layer 108 and a tie layer 110, which may be coextruded with the inner layer 108. In embodiments, the inner layer 108 may be coextruded as an AB layered coextrusion with the tie layer 110 as the B or top layer. In embodiments, the inner layer 108 and the tie layer 110 may be manually assembled as separate layers and joined in a subsequent fusion step. In this manner, the stiffness of the catheter shaft may be freely set along its length in accordance with the needs of a particular catheter user.

[0026] In process 300, in step 302, a reinforcement, such as reinforcement 116, may be placed on the inner liner a distance back from the distal end of the inner layer 108.

[0027] In process 300, at step 303, an outer jacket (e.g., distal outer layer 112) may be placed over the distal section. The outer jacket may cover the distal section so that the reinforcing material does not protrude through the distal end of catheter 100. In embodiments, catheter 100 may have a material transition prior to the reinforcing element to a material having a different durometer.

[0028] In the process 300 , in step 304 , a second outer jacket (eg, the proximal outer layer 114 ) may be placed over the proximal section 104 of the catheter 100 .

[0029] In process 300, in step 305, the assembly may be bonded and / or fused together. In the fusing step, the entire assembly may be encased in heat shrink tubing. The heat shrink tubing may then be passed through a heating chamber at a controlled speed. This process allows the components to reach a sufficient temperature (due to the compressive force applied by the heat shrink) to fusion bond the layers together to form the final composite catheter assembly. Process 300 may finally include removing the mandrel and / or heat shrink from the final catheter assembly.

[0030] 4A and 4B show a catheter 400 with multiple outer layer sections fused onto the inner layer and support element assembly. The catheter 400 may have each of the features described above with reference to the catheter 100, but with a modified outer layer configuration. For example, the catheter 400 may have a first outer layer 420, a second outer layer 422, a third outer layer 424, a fourth outer layer 426, and a luer hub 406. One or more of the first outer layer 420, the second outer layer 422, the third outer layer 424, and the fourth outer layer 426 may be made of a material having a stiffness different from the stiffness of the material making up one or more of the others of the first outer layer 420, the second outer layer 422, the third outer layer 424, and the fourth outer layer 426. In embodiments, the stiffness of the material making up the first outer layer 420, the second outer layer 422, the third outer layer 424, and the fourth outer layer 426 may increase from the distal end to the proximal end, such that the outermost end is made of the most flexible material. One or more of the first outer layer 420, the second outer layer 422, the third outer layer 424, and the fourth outer layer 426 may have a trackability that is different from the trackability of one or more of the others of the first outer layer 420, the second outer layer 422, the third outer layer 424, and the fourth outer layer 426. For example, the outer layers may have a first section and a second section, and the trackability of the first section may be better than the trackability of the second section.

[0031] 5 illustrates a process 500 for manufacturing a catheter, such as catheter 400. In process 500, in step 501, an inner liner may be applied to a mandrel. In embodiments, the inner liner may consist of inner layer 108 and tie layer 110, which may be coextruded with inner layer 108. In embodiments, inner layer 108 may be coextruded as an AB layered coextrusion with tie layer 110 as the B or top layer. In embodiments, inner layer 108 and tie layer 110 may be manually assembled as separate layers and joined in a subsequent fusion step. In this manner, the stiffness of the catheter shaft may be freely set along its length consistent with the needs of a particular catheter user.

[0032] In process 500, in step 502, a reinforcement, such as reinforcement 116, may be placed on the inner liner a distance back from the distal end of the inner layer 108.

[0033] In process 500, in step 503, outer jacket segments (e.g., first outer layer 420, second outer layer 422, third outer layer 424, fourth outer layer 426) may be placed onto the assembly starting from the distal section.

[0034] In process 500, step 504 continues by placing outer segments onto the assembly until the number of segments and durometer consistent with catheter design requirements are met.

[0035] In process 500, in step 505, the outer jacket may be bonded and / or fused to the inner liner. In the fusing step, the entire assembly may be encased in heat shrink tubing. The heat shrink tubing may then be passed through a heating chamber at a controlled speed. This process allows the components to reach a sufficient temperature (due to the compressive force applied by the heat shrink) to fusion bond the layers together to form the final composite catheter assembly. Process 500 may finally include removing the mandrel and / or heat shrink from the final catheter assembly.

[0036] 6A-6C show an example liner configuration for a catheter 600. The catheter 600 may have similar features as those described above with reference to the catheter 100. For example, the catheter 600 may have a first inner layer 608 that may be approximately the same length as the length of the catheter or may be shorter than the length of the catheter. The first inner layer 608 may be made of a material such as, for example, a low durometer polyolefin or polyethylene thermoplastic elastomer. The catheter 600 may have a second inner layer 628. The second inner layer 628 may be, for example, a fluoropolymer liner, such as PTFE. The second inner layer 628 may be an etched PTFE liner that may be manufactured by a solution coating manufacturing process. In embodiments, the second inner layer 628 can be a ram or paste extruded etched PTFE liner, and the catheter 600 can be assembled according to the process 800 described below. In this manner, flashing or blood leakage into the inner circumference of the catheter can be avoided. The second inner layer 628 can be shorter than the length of the catheter. In a catheter 600 having a first inner layer 608 and a second inner layer 628, the distal end of the catheter 600 can exhibit different characteristics than the proximal end. This can result in a more flexible or trackable tip distal section, while the proximal end of the catheter 600 can be optimized for pushability. The transition between the first inner layer 608 and the second inner layer 628 can be described as smooth and unobstructed.

[0037] The catheter 600 may have a third inner layer 630. The catheter 600 may have a distal outer layer 612. The distal outer layer 612 may be a single layer or multiple layers. The third inner layer 630 and the distal outer layer 612 may be of the same material. The catheter 600 may have a proximal outer layer 614. The proximal outer layer 614 may be a single layer or multiple layers. The catheter 600 may have a reinforcement layer 616 as described above. The catheter 600 may have a first tie layer 610 for the first inner layer 608. The catheter 600 may have a second tie layer or etch 632 for the second outer layer 612. The first and second tie layers 610, 32 may be of low durometer polymers as described above.

[0038] 7 illustrates a process 700 for manufacturing a catheter, such as catheter 600. In process 700, in step 701, a proximal liner (e.g., second inner layer 628) and a distal liner (e.g., first inner layer 608) may be applied to a mandrel. In embodiments, the inner liner may consist of inner layer 108 and tie layer 110, which may be coextruded with inner layer 108. In embodiments, the inner layers may be coextruded with tie layers (first tie layer 610 and second tie layer 632). The distal liner may be cut into a square and butted against the end of the proximal liner.

[0039] In process 700, a support element (e.g., stiffener 616) may be applied to the proximal and distal liners a distance back from the distal liner ends in step 702. In embodiments, in process 700, the ends of the support element may be terminated and contained within the catheter just back from the catheter tip, located distally, to ensure that the catheter is atraumatic.

[0040] In process 700, in step 703, an outer jacket segment (eg, distal outer layer 612 and / or proximal outer layer 614) may be placed onto the proximal liner-distal liner-support element assembly beginning with the distal section.

[0041] The process 700 may continue, at step 704, by placing outer jacket segments onto the proximal liner-distal liner-support element assembly until a sufficient number of sections and durometers are formed.

[0042] In process 700, in step 705, the outer jacket may be bonded and / or fused to the proximal and distal inner liners. In the fusing process, the entire assembly may be encased in heat shrink tubing for the fusing step. The heat shrink tubing may then be passed through a heating chamber at a controlled speed. This process allows the components to reach a sufficient temperature (due to the compressive force applied by the heat shrink) to fusion bond the layers together to form the final composite catheter assembly. Finally, in process 700, the mandrel and / or heat shrink may be removed from the final catheter assembly.

[0043] FIG. 8 illustrates a process 800 for manufacturing a catheter. In process 800, in step 801, a mandrel can be inserted into a paste or ram extruded PTFE etched inner liner. In embodiments, the PTFE etched inner liner can have an inner diameter smaller than the outer diameter of the mandrel. For example, the PTFE etched inner liner can have an inner diameter 2-8% smaller than the outer diameter of the mandrel. In embodiments, the mandrel can be 10-20 mm and can have a conical end that can aid in the insertion of the mandrel into the PTFE etched inner liner.

[0044] In process 800, at step 802, the PTFE etched inner liner can be cut perpendicular to the mandrel. The PTFE etched inner liner can be cut to a specific length. In embodiments, the PTFE etched inner liner can have an inner diameter that is smaller than the outer diameter of the mandrel so that the PTFE etched inner liner can remain snug on the mandrel as it is cut, thereby preventing the liner from springing back after cutting as occurs in conventional liner loading processes.

[0045] In process 800, a polyolefin-based elastomer can be fitted with a tie layer onto a mandrel in step 803. The polyolefin-based elastomer can be fitted with a tie layer, where the PTFE etched inner liner has been removed in step 802. The polyolefin-based elastomer can be abutted with the tie layer against the remaining PTFE etched inner liner on the mandrel, optimizing the bond between the two materials.

[0046] In process 800, in step 804, a polyolefin-based elastomer can be laminated with a tie layer to achieve a tight fit to the end edge of the mandrel and / or PTFE etched inner liner, creating an internal seal that can limit and / or prevent the ingress of other materials into the inner circumference of the finished catheter.

[0047] In process 800, optional support elements may be placed on the hybrid liner assembly in step 805. In embodiments, step 805 may include any of the aspects of step 802 described above.

[0048] In process 800, an outer layer segment may be placed onto the hybrid liner assembly in step 806. In embodiments, step 806 may include any of the aspects of step 703 and / or step 704 described above.

[0049] In process 800, the outer jacket may be bonded and / or fused to the hybrid liner assembly in step 807. In embodiments, step 807 may include any of the aspects of step 705 described above.

[0050] It is understood that the above description provides examples of the disclosed device. However, it is envisioned that other implementations of the invention may differ in detail from the above-described embodiment. Any reference to the invention or embodiments of the invention is intended to refer to the specific embodiment described at this point, and is not intended to imply any limitation on the scope of the invention as a whole. All terms regarding distinctions and disdain for certain features are intended to indicate that there is no preference for such features, but are not intended to completely exclude such features from the scope of the invention unless otherwise specified. All methods described herein can be performed in any suitable order, unless otherwise expressly specified or clearly contradicted by context.

Claims

1. A catheter comprising: an inner layer comprising a polyolefin-based or polyethylene-based thermoplastic elastomer material; An outer layer; a tie layer disposed between the inner layer and the outer layer, the tie layer comprising a low durometer polymer.

2. The catheter of claim 1 , wherein the inner layer comprises one or more lubricants.

3. 3. The catheter of claim 1, wherein the tie layer comprises maleic anhydride grafted linear low density polyethylene (LLDPE), maleic anhydride modified low density polyethylene (LDPE), or maleic anhydride modified ethylene vinyl acetate (EVA).

4. The catheter of claim 1 , further comprising a reinforcement material disposed between the inner layer and the outer layer.

5. The catheter of claim 4 , wherein the stiffener comprises one or more filamentary coil wires wrapped circumferentially around the longitudinal axis of the catheter.

6. 5. The catheter of claim 4, wherein the reinforcement is a wire pattern of a braided design interwoven circumferentially about the longitudinal axis of the catheter.

7. The catheter of claim 6 , wherein the braid design includes a variation in density or pix per inch along the length of the braid design.

8. The catheter of claim 6 , wherein the braid design comprises a bottom-one-top-one-bottom-one, bottom-two-top-two-bottom-two, or bottom-one-top-two-bottom-two pattern.

9. The catheter of any one of claims 4 to 8, wherein the reinforcing material includes at least one of steel, nitinol, tungsten, a non-metallic monofilament, a fiber bundle, aramid, a polymer, nylon, or LCP.

10. 9. The catheter according to claim 4, wherein the reinforcement includes a circumferential reinforcement provided between the inner layer and the outer layer, and a longitudinal reinforcement extending along the longitudinal axis of the catheter.

11. The catheter of claim 6 , wherein the braid design includes a first braided reinforcement and a second braided reinforcement disposed over the first braided reinforcement.

12. The catheter of claim 11 , wherein the second braided reinforcement is made of a material different from the material comprising the first braided reinforcement.

13. 13. The catheter of claim 11 or 12, wherein the second braided reinforcement is configured with a different geometric shape than the geometric shape comprising the first braided reinforcement.

14. The catheter of claim 4 , wherein the reinforcement material is embedded within the tie layer.

15. The catheter of claim 4 , wherein the tie layers are disposed above and below the stiffener.

16. The catheter of claim 15 , wherein the tie layer is disposed between a braided reinforcement and a coil reinforcement.

17. 16. The catheter of claim 15, wherein the tie layer is disposed between any reinforcement layers.

18. The catheter of claim 4 , wherein the stiffener terminates a distance from the distal end of the catheter.

19. The catheter of claim 1 , wherein the outer layer has a first section and a second section, the stiffness of the first section being different from the stiffness of the second section.

20. The catheter of claim 1 , wherein the outer layer has a first section and a second section, the first section having better trackability than the second section.

21. The catheter of claim 1 , wherein one or more of the inner layer, the tie layer, or the outer layer are crosslinked using E-beam.

22. 2. The catheter of claim 1, wherein the inner layer includes a first inner layer disposed on a distal portion of the catheter and made of a thermoplastic elastomer material, and a second inner layer disposed on a proximal portion of the catheter proximal to the first inner layer, the second inner layer being made of PTFE.

23. The catheter of claim 1 , wherein the distal end of the catheter comprises a radiopaque tip.

24. 24. The catheter of claim 23, wherein the radiopaque tip is comprised of a polymer containing one or more of the following additives: tungsten, barium sulfate, bismuth subcarbonate, or bismuth oxychloride.

25. 25. The catheter of claim 24, wherein the radiopaque tip comprises a split marker band.

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