Medical catheter, medical system and procedure for manufacturing a medical catheter

Abstract

A medical catheter with a catheter tube and at least one inner lumen (18), wherein a reinforcing element (10) is associated with the catheter tube, characterized in that the reinforcing element (10) comprises at least two reinforcing structures (11, 12), wherein a first reinforcing structure (11) is formed from at least two monofilaments (16) and a second reinforcing structure (12) is formed from at least one multifilament bundle (17), wherein the monofilaments (16) and the multifilament bundle (17) are interwoven, and wherein the monofilaments (16) have a first helical winding direction around the longitudinal axis of the catheter tube and the multifilament bundle (17) has a second helical winding direction around the longitudinal axis of the catheter tube, wherein the first winding direction is opposite to the second winding direction.wherein the monofilaments (16) of the first reinforcing structure (11) are formed as a metallic coil (14) and the multifilament bundle (17) of the second reinforcing structure (12) comprises a bundle of individual plastic fibers (15), and wherein the ratio between monofilaments (16) of the first reinforcing structure (11) and the multifilament bundle (17) or multifilament bundles (17) of the second reinforcing structure (12) is 2 / 1, wherein the at least two monofilaments (16) are spaced apart from each other.

Description

[0001] The invention relates to a medical catheter according to the preamble of claim 1. Furthermore, the invention relates to a medical system and a method for manufacturing a medical catheter.

[0002] Such a medical catheter is known, for example, from DE 697 20 583 T2. The known catheter has a tubular body with an inner lumen. The tubular body can be made of a polymeric material for the catheter tube and a metallic reinforcing braid. The reinforcing braid is formed from stainless steel wires and extends along the tubular body. To increase the kinking resistance of the catheter, conventional reinforcing braids have a large wire diameter and thus a large thickness.

[0003] US patent 6,942,654 B1 discloses a catheter with an inner lumen and a catheter shaft having a multilayered structure. The catheter shaft comprises an inner polymer layer surrounded by a braided reinforcing layer, which in turn is surrounded by an outer polymer layer.

[0004] US Patent 2008 / 0103483A1 discloses a catheter with a sheath and reinforcing elements that are helically interwoven and have different winding directions. The catheter may also include a longitudinal reinforcing element. The reinforcing elements may be made of a polymer or a metal.

[0005] For intracranial medical catheters used to aspirate thrombi, it is particularly important that the catheter's inner lumen has the largest possible cross-sectional diameter to prevent the aspirated thrombi from completely obstructing it. However, the available cross-sectional diameter of the inner lumen is generally limited not only by the available outer cross-sectional diameter of the catheter, but also by the thickness of the catheter tubing and the thickness of the reinforcing braid. Since the outer cross-sectional diameter of the catheter cannot exceed a maximum value due to the required compatibility with a catheter sheath, the use of conventional thick steel wire reinforcing braids inevitably reduces the cross-sectional diameter of the inner lumen.

[0006] Furthermore, the catheter can be adversely prone to ovalization due to the metallic reinforcing mesh. Ovalization of the catheter refers to a deformation of the catheter's cross-section and thus also of its inner lumen. In particular, the cross-sectional geometry of a catheter with a typical cylindrical shape can, at least locally, become oval due to ovalization. In extreme cases, the catheter's cross-section could be deformed to such an extent that the inner lumen is blocked and no longer has a free passage.

[0007] The invention is therefore based on the objective of providing a medical catheter in which the largest possible cross-sectional diameter of the inner lumen can be achieved while maintaining sufficient kink resistance. The invention is further based on the objective of providing a medical system and a method for manufacturing a medical catheter.

[0008] This problem is solved according to the invention by a medical catheter having the features of claim 1. With regard to the medical system, the problem is solved by the subject matter of claim 6 and with regard to the method by the subject matter of claim 7.

[0009] The invention is based on the concept of a medical catheter comprising a catheter tube and at least one inner lumen, wherein a reinforcing element is associated with the catheter tube. The reinforcing element comprises at least two reinforcing structures, a first reinforcing structure being formed from at least two monofilaments and a second reinforcing structure being formed from at least one multifilament bundle. The monofilaments and the multifilament bundle are interwoven. The monofilaments have a first helical winding direction around the longitudinal axis of the catheter tube, and the multifilament bundle has a second winding direction around the longitudinal axis of the catheter tube, the first winding direction being opposite to the second winding direction.

[0010] The reinforcing element can be a separate component from the catheter tubing or form a separate component of the catheter itself. The reinforcing element can be permanently attached to the catheter. However, it can have different mechanical properties than the catheter tubing. In general, the reinforcing element modifies the mechanical properties of the catheter tubing. For example, the reinforcing element can be designed to improve the bending behavior of the catheter tubing. In particular, the reinforcing element can increase the bending stability, or kink resistance, of the catheter tubing. The reinforcing element has the advantage that the catheter can be easily maneuvered within a blood vessel, even at tight bends. This maintains the catheter's navigation capabilities. Furthermore, the reinforcing element prevents deformation of the inner lumen.

[0011] Within the scope of the application, a multifilament bundle comprises at least two individual monofilaments. The monofilaments are designed as plastic fibers. The formation of a bundle, within the scope of the application, means that the individual monofilaments of the multifilament bundle are in contact with each other, particularly at least partially, and run parallel to each other in the same direction. In particular, two adjacent monofilaments are in contact along a line and run in the same winding direction.

[0012] The multifilament bundle can assume any geometric shape, particularly a flat geometric shape. It is therefore conceivable that the multifilament bundle has a ribbon-like geometric shape. The invention thus has the advantage that by combining at least two monofilaments with a multifilament bundle, especially a flat multifilament bundle, the wall thickness of the catheter can be significantly reduced. Accordingly, the diameter of the inner lumen can advantageously be increased while maintaining the same outer diameter of the catheter. This prevents clogging of the inner lumen, for example, by aspirated thrombi.

[0013] The at least two monofilaments and the multifilament bundle are interwoven. Thus, the at least two monofilaments and the multifilament are connected. The multifilament bundle can be braided or woven into the at least two monofilaments. The winding directions of the at least two monofilaments and the multifilament bundle are different. Compared to the known reinforcing braid made of intersecting steel wires, the woven multifilament bundle can significantly reduce the diameter of the reinforcing element. Therefore, by reducing the diameter of the reinforcing element while maintaining the same outer diameter of the catheter, the diameter of the inner lumen can preferably be increased.

[0014] The reinforcing element according to the invention, which comprises at least two reinforcing structures, can be used for any type of medical catheter for various functions, such as feeding catheters, temperature control catheters, or aspiration catheters. Since the reinforcing element prevents deformation of the inner lumen, it avoids, for example, any impairment of cooling performance in inner lumens containing cooling fluid. In inner lumens designed, for example, as a passageway for guiding medical instruments to the treatment site, the accessibility of the medical instruments is maintained even when the catheter is guided through a tight bend.

[0015] For example, a medical catheter for intracranial use can have a multi-layered construction. The catheter tube can consist of three layers. The inner layer, which is directly adjacent to the inner lumen, can be made of a friction-reducing material, particularly a plastic such as PTFE, or other friction-reducing materials such as FEP or HDPE. Friction-reducing materials such as a PTFE-PI compound, PFA, or PE are also conceivable. Advantageously, the inner layer is made of a chemically resistant material.

[0016] The reinforcing element with at least two reinforcing structures can be attached to the inner layer. The reinforcing element thus forms the second layer.

[0017] Furthermore, a third layer can be applied to the reinforcing element. This third layer can preferably be a polymer layer with various Shore hardnesses. In particular, the third layer can have a modulus of elasticity in the range of 12 MPa to 520 MPa (defined according to ISO 178). The third layer can preferably be made of a thermoplastic elastomer, in particular polyether block amide (PEBA), polyurethane (PU), polyamide (PA), or comparable materials. The third layer can be directly extruded, dipped, or applied to the other layers using a reflow process.

[0018] Further preferred embodiments of the invention are specified in the dependent claims.

[0019] In general, under surface pressure, the multifilament bundle can be transformed from a bundled arrangement to a flat arrangement. Such surface pressure can occur when the medical catheter is advanced through tight vascular bends.

[0020] In particular, the planar arrangement of the multifilament bundle can be determined by a ratio between its width and height. The height h of the multifilament bundle is determined essentially perpendicular to the braiding plane. The width b of the multifilament bundle is determined in the braiding plane. For the planar arrangement of the multifilament bundle, the bundle has a greater width b than height h. Specifically, the h / b ratio between the height and width of the multifilament bundle can range from 0.01 to 0.8, and particularly 0.5. In the planar arrangement with a greater width than height, the multifilament bundle resembles a ribbon fiber. This allows for a further reduction in catheter wall thickness.

[0021] The reinforcing element comprises a varying number of monofilaments and multifilament bundles. In particular, the ratio between monofilaments of the first reinforcing structure and multifilament bundles of the second reinforcing structure can be 4 / 2 or 8 / 4. These ratios mathematically correspond to the 2 / 1 ratio according to the invention. For example, 4 wires and 2 multifilament bundles, or 8 wires and 4 multifilament bundles, can be interwoven to form the reinforcing element.

[0022] The first reinforcing structure comprises a first material, namely a metal, and the second reinforcing structure comprises a second material, namely a plastic. For example, the first reinforcing structure can be formed from at least one metal wire. Preferred materials are stainless steel or a nickel-titanium alloy. The wire can preferably be X-ray-proof. The second reinforcing structure, which is formed from at least one multifilament bundle, comprises a bundle of individual plastic fibers, in particular multifilament polymer fibers. Preferably, the plastic fibers can be made of para-aramid. It is particularly advantageous if the bundle is formed from a material that has low weight or low elongation or high tensile strength. Furthermore, it is particularly advantageous if the bundle is formed from a material that has a temperature resistance of up to 650°C.

[0023] In general, the wire(s) or individual fibers can be designed as round wires or round fibers, or as flat wires or flat fibers. The combination of two different materials for the first and second reinforcement structures has the advantage that the reinforcement element can be flexibly adapted to the various requirements for different applications of the medical catheter with regard to friction behavior, bending flexibility, kink resistance, especially at sharp bends at bifurcations, ovalization behavior, or maneuverability.

[0024] The at least two monofilaments form a helical winding around the longitudinal axis of the catheter tube. For example, the at least two monofilaments can be configured as a wire braid. A single wire or multiple wires can be used for this purpose. The wire(s) can be braided to form meshes or interwoven with themselves. The meshes of the braid form a basic structure that largely determines the mechanical properties of the reinforcing element and supports the braided multifilament bundle. The braided configuration has the advantage of improving the controllability and maneuverability of the catheter, particularly at bifurcations. Advantageously, the wire braid can also be used to transmit torque applied proximally.

[0025] Furthermore, at least two monofilaments are formed as a coil. The coil extends helically around the longitudinal axis of the catheter tube. This coil configuration has the advantage that, compared to a braid, the diameter of the catheter wall thickness can be significantly reduced.

[0026] The reinforcing element is designed as a coil with an interwoven polymer fiber bundle forming a multifilament bundle. The winding direction of the interwoven multifilament bundle differs from that of the coil. In other words, the multifilament bundle runs in a different direction than the coil.

[0027] Preferably, the multifilament bundle is aligned parallel to the longitudinal axis of the catheter tube. In other words, the multifilament bundle can be arranged axially or longitudinally within the catheter tube. The multifilament bundle is interwoven into at least two monofilaments. This interweaving of the multifilament bundle into the at least two monofilaments has the advantage of increasing the tensile stiffness of the reinforcing element.

[0028] In a further embodiment, the catheter is designed as a multi-lumen catheter, with the reinforcing element forming part of the wall of at least one inner lumen. For example, the inner circumference of the inner lumen can be lined by a multi-layered wall, whereby the wall supports the inner lumen and thus prevents deformation of the inner lumen. Preferably, the wall can be formed from three layers, the innermost layer, which directly borders the inner lumen, being made of a friction-reducing material. The reinforcing element can be arranged on the innermost layer. A third layer, which is particularly designed as a polymer layer, can be arranged on the reinforcing element. Advantageously, each inner lumen is assigned a reinforcing element. The multi-lumen design of the catheter comprises at least two inner lumens.This has the advantage that the catheter, with its multiple inner lumens, can perform various functions simultaneously in a single device, such as aspiration and infusion.

[0029] Preferably, the reinforcing element extends over the entire length of the inner lumen. Specifically, the inner lumen can be completely lined by the reinforcing element. This is advantageous for providing the flexural and kink-resistant properties of the catheter tube across all areas of the catheter tube.

[0030] In a further embodiment, the catheter has a diameter of at most 8 Fr, in particular at most 7 Fr, in particular at most 6 Fr, in particular at most 5 Fr, in particular at most 4 Fr, in particular at most 3 Fr, in particular at most 2.5 Fr, in particular at most 2 Fr.

[0031] The application further claims a medical system with a medical catheter according to one of the preceding embodiments, which further comprises an aspiration unit for aspirating substances from a blood vessel, which is connectable to the inner lumen of the medical catheter. The aspiration unit can be a suction device or a syringe.

[0032] Furthermore, the application claims a method for manufacturing a medical catheter, which comprises a catheter tube having a reinforcing element. The reinforcing element comprises at least two reinforcing structures, wherein a first reinforcing structure is formed from at least two monofilaments and a second reinforcing structure is formed from at least one multifilament bundle, the multifilament bundle having several monofilaments which are extruded by means of an extruder and bundled by means of an electric field.The at least two monofilaments of the first reinforcement structure and the multifilament bundle are interwoven, wherein the monofilaments of the first reinforcement structure have a first helical winding direction around the longitudinal axis of the catheter tube and the multifilament bundle has a second helical winding direction around the longitudinal axis of the catheter tube, wherein the first winding direction is opposite to the second winding direction, wherein the monofilaments of the first reinforcement structure are formed as a metallic coil and the multifilament bundle of the second reinforcement structure comprises a bundle of individual plastic fibers, and wherein the ratio between monofilaments of the first reinforcement structure and the multifilament bundle or bundles of the second reinforcement structure is 2 / 1, wherein the at least two monofilaments of the first reinforcement structure are spaced apart from each other.The monofilaments of the multifilament bundle can be formed, for example, by fibers produced using a process similar to electrospinning. This means that the monofilaments or fibers are extruded through a die. The applied electric field then bundles or draws the monofilaments together at a single point, thus forming a multifilament bundle.

[0033] In a further preferred embodiment, the monofilaments of the multifilament bundle are further processed after bundling. The resulting multifilament bundle can be processed in such a way that advantageous material properties can be achieved.

[0034] Preferably, after bundling, the monofilaments are surface-treated, in particular plasma-treated or dip-coated with subsequent UV curing, such that the monofilaments exhibit hydrophobic, hydrophilic, adhesive, abrasion-resistant, or anti-wicking properties after treatment. Anti-wicking properties refer to the absence of wicking activity in the formed coated multifilament bundle. Wicking activity generally refers to multifilament bundles that, due to their surface properties, can transport liquid along the fiber by capillary action. Advantageously, the surface treatment allows for the adjustment of any desired surface properties of the multifilament bundle to optimally ensure various catheter functionalities.It is also conceivable that the biocompatibility or X-ray visibility of the multifilament bundle could be adjusted via surface treatment. Furthermore, surface treatment can advantageously prevent material fatigue.

[0035] Furthermore, the medical system and the procedure may alternatively or additionally exhibit one or a combination of several of the features previously mentioned in relation to the medical catheter.

[0036] The following shows Fig. 1 a detailed view of a reinforcement element for a medical catheter according to a first embodiment; Fig. 2 A detailed view of a reinforcement element for a medical catheter according to a further embodiment.

[0037] The exemplary embodiments are not part of the invention and serve only for clarification.

[0038] In the following description, the same reference symbols are used for identical and equivalent parts.

[0039] Fig. Figure 1 shows a detailed view of a reinforcement element 10 for a medical catheter (not shown) according to a first embodiment. The catheter can comprise a catheter tube (not shown) and at least one inner lumen 18, with the reinforcement element 10 being associated with the catheter tube.

[0040] The reinforcing element 10 comprises two reinforcing structures 11, 12. A first reinforcing structure 11 is formed by a metallic braid 13. The braid 13 comprises two monofilaments 16. The monofilaments 16 are designed as wires which are interwoven to form meshes in the braid 13. Preferred materials are stainless steel or a nickel-titanium alloy. Alternatively, the braid 13 can be formed from a single wire as a monofilament 16 which is interwoven with itself.

[0041] The braid 13 forms a tubular body around a longitudinal axis of the inner lumen 18. A second reinforcing structure 12 is arranged axially or longitudinally. The second reinforcing structure 12 is formed by a multifilament bundle 17, or a bundle of individual plastic fibers 15. The multifilament bundle 17 comprises several monofilaments or individual plastic fibers 15. For example, the bundle is formed from para-aramid fibers. The material of the bundle differs from the material of the braid 13.

[0042] The multifilament bundle 17 is interwoven with the braid 13. Specifically, the multifilament bundle 17 is woven into the braid 13. The multifilament bundle 17 has a different winding direction than the braid 13. In particular, the multifilament bundle 17 extends axially along the longitudinal axis of the reinforcing element 10 or the inner lumen 18.

[0043] The multifilament bundle 17 has a planar arrangement. The individual plastic fibers 15 of the multifilament bundle lie parallel to each other and are arranged in the plane of the braid. This allows the thickness or diameter of the reinforcing element 10, and thus the catheter wall thickness, to be significantly reduced. The individual plastic fibers 15 of the multifilament bundle 17 can be in direct contact with each other or be partially woven into adjacent meshes of the braid 13. The multifilament bundle 17 is designed such that, during the braiding process with the braid 13, it is transformed from a bundled arrangement to a planar arrangement perpendicular to a bundle axis.

[0044] The meshes of the braid 13 form a basic structure that largely determines the mechanical properties of the reinforcing element 10 and supports the interwoven multifilament bundle 17. The braided design 13 has the advantage of improving the controllability and navigation of the catheter, particularly at bifurcations.

[0045] Fig. Figure 2 shows a detailed view of a reinforcement element 10 for a medical catheter (not shown) according to a further embodiment. The catheter can comprise a catheter tube (not shown) and at least one inner lumen 18, with the reinforcement element 10 being associated with the catheter tube.

[0046] The reinforcing element 10 comprises two reinforcing structures 11, 12. A first reinforcing structure 11 is formed by a metallic coil 14. The coil 14 comprises a monofilament 16. The monofilament 16 is formed as a wire. Preferred materials are stainless steel or a nickel-titanium alloy.

[0047] The coil 14 forms a tubular body around a longitudinal axis of the inner lumen 18. The coil forms a helical winding. This winding extends helically around the longitudinal axis of the inner lumen 18, or catheter tubing. The coil 14 has a first winding direction around the longitudinal axis. A second reinforcing structure 12 is arranged in a winding direction opposite to this. The second reinforcing structure 12 is formed by a multifilament bundle 17, or a bundle of individual plastic fibers 15. The bundle comprises several monofilaments or individual plastic fibers 15. For example, the bundle is formed from para-aramid fibers. The material of the bundle differs from the material of the coil 14. The multifilament bundle 17 is interwoven with the coil 14 in a winding direction opposite to this. In particular, the multifilament bundle 17 extends along the longitudinal axis of the reinforcing element 10, or the inner lumen 18.

[0048] The multifilament bundle 17 has a planar arrangement. The individual plastic fibers 15 of the multifilament bundle 17 lie parallel to each other and are arranged in a common braiding plane with the coil 14. In other words, the coil 14 and the braided multifilament bundle 17 form a type of braid. Thus, the thickness or diameter of the reinforcing element 10, and therefore the catheter wall thickness, can be significantly reduced. The multifilament bundle 17 is designed such that, during the braiding process with the coil 14, it is transformed from a bundled arrangement to a planar arrangement perpendicular to a bundle axis. Reference symbol list 10 Reinforcing element 11 first reinforcement structure 12 second reinforcement structure 13 metal mesh 14 Coil 15 plastic fiber 16 Monofilament 17 multifilament bundles 18 internal lumens

Claims

[1] Medical catheter with a catheter tube and at least one inner lumen (18), wherein a reinforcing element (10) is associated with the catheter tube, characterized by, that the reinforcing element (10) comprises at least two reinforcing structures (11, 12), wherein a first reinforcing structure (11) is formed from at least two monofilaments (16) and a second reinforcing structure (12) is formed from at least one multifilament bundle (17), wherein the monofilaments (16) and the multifilament bundle (17) are interwoven, and wherein the monofilaments (16) have a first helical winding direction around the longitudinal axis of the catheter tube and the multifilament bundle (17) has a second helical winding direction around the longitudinal axis of the catheter tube, wherein the first winding direction is opposite to the second winding direction, wherein the monofilaments (16) of the first reinforcing structure (11) are formed as a metallic coil (14) and the multifilament bundle (17) of the second reinforcing structure (12) comprises a bundle of individual plastic fibers (15),and wherein the ratio between monofilaments (16) of the first reinforcing structure (11) and the multifilament bundle (17) or multifilament bundles (17) of the second reinforcing structure (12) is 2 / 1, wherein the at least two monofilaments (16) are spaced apart from each other. [2] Medical catheter according to claim 1, characterized by , that the multifilament bundle (17) is designed such that, in a braiding process with the monofilament (16), it can be transformed from a bundled arrangement to a planar arrangement orthogonally to a bundle axis. [3] Medical catheter according to any of the preceding claims, characterized by , that the catheter is designed as a multi-lumen catheter, wherein the reinforcing element (10) forms part of the wall of at least one inner lumen (18). [4] Medical catheter according to any of the preceding claims, characterized by, that the reinforcing element (10) extends over the entire length of the inner lumen (18). [5] Medical catheter according to any of the preceding claims, characterized by , that the catheter has a diameter of at most 8 Fr, in particular at most 7 Fr, in particular at most 6 Fr, in particular at most 5 Fr, in particular at most 4 Fr, in particular at most 3 Fr, in particular at most 2.5 Fr, in particular at most 2 Fr. [6] Medical system comprising a medical catheter according to one of the preceding claims and an aspiration unit for aspirating substances from a blood vessel, which can be connected to the inner lumen of the medical catheter. [7] Method for manufacturing a medical catheter with a catheter tube which has a reinforcing element (10), characterized bythat the reinforcing element (10) comprises at least two reinforcing structures (11, 12), wherein a first reinforcing structure (11) is formed from at least two monofilaments (16) and a second reinforcing structure (12) is formed from at least one multifilament bundle (17), wherein the multifilament bundle (17) has several monofilaments which are extruded by means of an extruder and bundled by means of an electric field, and wherein the monofilaments (16) of the first reinforcing structure (11) and the multifilament bundle (17) are interwoven, wherein the monofilaments (16) of the first reinforcing structure (11) have a first helical winding direction around the longitudinal axis of the catheter tube and the multifilament bundle (17) has a second helical winding direction around the longitudinal axis of the catheter tube, wherein the first winding direction is opposite to the second winding direction,wherein the monofilaments (16) of the first reinforcing structure (11) are formed as a metallic coil (14) and the multifilament bundle (17) of the second reinforcing structure (12) comprises a bundle of individual plastic fibers (15), and wherein the ratio between monofilaments (16) of the first reinforcing structure (11) and the multifilament bundle (17) or multifilament bundles (17) of the second reinforcing structure is 2 / 1, wherein the at least two monofilaments (16) of the first reinforcing structure (11) are spaced apart from each other, [8] Method according to claim 7, characterized by , that the monofilaments (16) are further processed after bundling. [9] Method according to claim 8, characterized by, that the monofilaments (16) are surface-treated after bundling, in particular plasma-treated or dip-coated with subsequent UV curing, such that the monofilaments (16) have hydrophobic or hydrophilic or adhesive or abrasion-resistant or anti-wicking properties after treatment.

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