Medical catheter for insertion into a hollow body organ

Abstract

A medical catheter (10) for insertion into a hollow body organ having at least one proximal section and one distal section (11), the catheter (10) comprising: - at least one feed channel (12) for feeding a medical implant; - a liner (13) formed by spirally winding a layer (14) onto a mandrel (15) and designed as an inner layer of the catheter (10) facing an inner lumen (16) of the supply channel (12) during use; and - a jacket (17) which forms an outer layer of the catheter (10), characterized in that the wall thickness of the liner (13) in the distal section (12) is between 20% and 50% of the total wall thickness of the catheter (10), wherein the liner (13) comprises several layers (14) which are arranged one above the other in the radial direction of the catheter (10).

Description

The invention relates to a medical catheter for insertion into a hollow body organ according to the preamble of claim 1.US 4516972 A discloses a catheter for insertion into a cardiovascular system. A helically wound layer of flexible material is embedded in a wall of the catheter to provide axial stiffness of the catheter that is intended to facilitate insertion into the cardiovascular system. In this way, it is to be achieved that the catheter has a sufficiently high stiffness and an increased flexibility to be controllable in curved blood vessels.In medical catheters, in particular delivery catheters in which stents are delivered, the problem often arises that the stents become smaller and smaller and have a plurality of webs or wires, which can lead to increased friction during delivery in a catheter lumen. In particular in the distal section of the catheter, in view of the increasingly curved anatomy, this can lead to challenges with regard to stretching and narrowing of the catheter lumen, which in turn can result in the implant being stuck.In general, different requirements are placed on the catheter. In order to enable access of the catheter to small blood vessels or the permeability of the catheter in strongly curved vessels, a relatively high flexibility is required. At the same time, the catheter should have a relatively high axial rigidity under axial compressive load, i.e. during pushing of the catheter. Axial rigidity should also be ensured when the catheter is pulled or when an implant, for example a stent, is guided through the catheter to the destination.In the known medical catheter, the contradiction between flexibility and axial stiffness of the catheter is to be resolved by changing the pitch of the helically wound layer. A disadvantage of these catheters is that these catheters have low axial stiffness and too great a total wall thickness. This disadvantage is especially evident when guiding the catheter through tight vessel curvatures.US 2013 0 253 417 A1 discloses a catheter device with a catheter tube. The catheter tube includes a distal liner, an annular region of elastomeric adhesive surrounding a distal coil with spring force, and an outer sheath.US 2022 0 211 975 A1 discloses a neurovascular catheter, the catheter comprising an elongate flexible tubular body having a proximal portion, a distal portion and a sidewall defining a central lumen.The invention is therefore based on the object of specifying a catheter for insertion into a hollow body organ, which catheter has good accessability for medical implants.According to the invention, this object is achieved by medical catheters for insertion into a hollow body organ having the features of claim 1.Specifically, this object is achieved by a medical catheter for insertion into a hollow body organ having at least a proximal section and a distal section, wherein the catheter comprises at least one feed channel for feeding a medical implant, a liner which is formed by spirally winding a layer onto a mandrel and is formed as an inner layer of the catheter facing an inner lumen of the feed channel in use, and a jacket which forms an outer layer of the catheter. The wall thickness or thickness of the liner in the distal section is between 20% and 50% of the total wall thickness or thickness of the catheter.The invention has several advantages.To increase the resistance to buckling of the catheter as it is moved within a patient's body, the catheter has two sections, a proximal section and a distal section. The proximal portion is relatively stiff and the distal portion is relatively flexible. The distal portion may be formed as a tip of the catheter. In a balloon catheter, a balloon is disposed in the distal portion.Furthermore, the catheter has at least one feed channel for feeding a medical implant. The feed channel is designed as a through channel and makes it possible to guide the implant to the treatment site.In addition, the catheter has a liner which is formed by spirally winding a layer onto a mandrel and is formed as an inner layer of the catheter which, in use, faces an inner lumen of the feed duct. This is to be understood as meaning that the entire liner is produced by helical winding onto a mandrel. In other words, the liner is formed from the inside to the outside or from one side of the liner to the other by spirally winding it onto a mandrel. If the liner has a plurality of layers, all layers of the liner are formed by helical winding. The entire wall thickness of the liner is formed from layers by helical winding.According to the invention, the wall thickness of the liner in the distal section is between 20% and 50% of the total wall thickness of the catheter. The wall thickness of the liner in the distal section is preferably between 20% and 30% of the total wall thickness of the catheter, in particular between 20% and 40% of the total wall thickness of the catheter. This has the advantage that high flexibility of the catheter in the distal section is achieved in this region. A ratio between the wall thickness of the liner and the wall thickness of the catheter in the distal section is adapted such that the catheter in the distal section on the one hand is flexible and on the other hand has sufficient axial stiffness. This allows the delivery of otherwise difficult implants.The wall thickness of the liner and the related total wall thickness of the catheter are determined at the same location. In other words, the wall thickness of the liner at the same cross-sectional location in the distal section is between 20% and 50% of the total wall thickness of the catheter.The greater the proportion of the liner in the total wall thickness of the catheter, the more strongly the properties of the catheter are determined by the liner. This relates, for example, to the bending stiffness and thus the flexibility. The closer the portion of the wall thickness of the liner is to the upper limit of 50%, the more rigid the catheter is. Conversely, the influence of the liner decreases the closer the proportion is to the lower limit of 20%.It has been found that in the range from 20% to 50%, the effect of the liner on the properties of the catheter in the distal region, in particular in the region of the catheter tip, is particularly good.The catheter tip is the distal end of the catheter, which is important for navigating the catheter in highly curved vessels. In addition, the implant exits the catheter when released. The catheter tip has a certain length, which can vary depending on the catheter. The length of the catheter tip corresponds to the distal portion. The diameter of the catheter increases further proximally and is larger than in the region of the catheter tip.The liner comprises a plurality of layers which are arranged one above the other in the radial direction of the catheter. The individual layers can be arranged one after the other by spiral winding. Individual layers can be wound left-handed and right-handed on a mandrel. In other words, the mandrel is completely covered by individual layers. Furthermore, the wall thickness of the liner is determined by the number of layers. The wall thickness of the liner can be adjusted by the number of layers. It is particularly advantageous if the liner has a low wall thickness, in particular in comparison with conventional liners. Further, the plurality of layers may be formed of different materials. As a result, different layers can have different properties, such as different axial stiffness, elongation and / or flexibility.Preferred embodiments of the invention are set forth in the dependent claims.The liner can have a wall thickness between 5 μm and 25 μm, in particular at most 23 μm, in particular at most 20 μm, in particular at most 19 μm, in particular at most 18 μm, in particular at most 17 μm, in particular at most 15 μm. Due to a small wall thickness, the liner has high flexibility, which is advantageous in particular for use in curved blood vessels.In a further preferred embodiment, the liner is formed from a perfluorinated or partially fluorinated polymer (e.g. PTFE, PVDF), polyolefin (e.g. PP, PE), polyurethane (e.g. thermoplastic polyurethane, hydrophilic polyurethane), polyamide (e.g. PA6.6), polyester (e.g. PLA, PLGA, PET), polysulfone (e.g. PSU), polyetheretherketone (PEEK), biological and / or protein-based polymer. For the production of the liner, it is consequently possible to select from a multiplicity of polymers the one which has the desired properties for the respective field of application. Furthermore, different layers of the liner can be made from different polymers. Thus, a layer may be formed of PTFE, while another layer is formed of PEEK. Thus, the liner can be formed, for example, from fluorinated polymers, such as PTFE, and / or from polymers provided with additives (compounds). As a result, it is possible, for example, to reduce the coefficient of friction of the liner in order to achieve a low-friction feeding of a medical implant. Such additives may be hydrophilic polymers, such as hydrophilic thermoplastic polymers (TPU), biopolymers, polyethylene glycol (PEG) and / or polyvinyl acetate (PVA).The catheter may comprise only one inner lumen which may serve for delivering a medical implant. Alternatively, the catheter can comprise a plurality of inner lumens or be designed as a multilumen catheter with a plurality of channels, wherein at least one liner can be provided for each inner lumen or channel. Alternatively, only one channel or only some of the channels or inner lumens may have a liner.The catheter preferably has an inflation channel which is fluidically connected to a balloon and is arranged next to the feed channel, in particular parallel, next to the feed channel. The liner can be formed as a layer facing an inner lumen of the inflation channel. The inflation channel is provided for filling the balloon with a fluid in order to expand the balloon or for discharging the fluid from the balloon again in order to compress the balloon. The fluid connection enables the supply of a gaseous and / or a liquid fluid, for example. Air or NaCl, or a mixture thereof. The parallel arrangement of the channels increases the stiffness of the catheter. A liner facing the inner lumen of the inflation channel can restrict a strong expansion of the inflation channel in the radial direction. In addition to the supply channel and the inflation channel, the catheter can comprise further channels or inner lumens, which can have a liner.The catheter can have at least one coil which is arranged, in particular directly, on an outer wall of the liner. For example, the coil can be formed from a flexurally rigid material. In this case, the coil can be arranged in the longitudinal direction of the liner in order to increase the bending stiffness of the liner in the longitudinal direction. Furthermore, the coil can be formed as nickel-titanium wire, stainless steel wire and / or wire from another metallic material and can be arranged directly on an outer wall of the liner. As a result, the mechanical properties of the liner can be influenced by the coils. Alternatively, a plurality of coils may be arranged on the outer wall.The coil can have a wire diameter between 15 μm and 55 μm, in particular at most 50.8 μm, in particular at most 38.1 μm, in particular at most 25.4 μm, in particular at most 19.05 μm. The small diameter of the coil allows it to be used in microcatheter systems.Furthermore, the coil can be formed from at least one wire, in particular two wires arranged in parallel, in particular three wires arranged in parallel, in particular four wires arranged in parallel. The parallel wires result in a flat coil angle, so that a high flexibility of the catheter and a high torque transmission are achieved. The coils are preferably formed by winding (coiling) the wire or by winding a plurality of wires on an outer wall of the liner. Alternatively, the coils may be formed by braiding (brazing) multiple wires.In a further preferred embodiment, the jacket is arranged on the coil and / or the jacket embeds the coil, in particular completely. It is preferably provided that the jacket is formed from a plastic material.Such materials have high extensibility and can be easily produced, for example, by an electro-spinning process. The plastic material makes it possible, on the one hand, to produce a particularly thin and fine-pored jacket. On the other hand, the plastic material already has a high flexibility in itself, so that a high flexibility of the catheter is achieved.Preferably, the sheath has a Shore hardness in the distal section of at most 25D, in particular at most 70A, in particular at most 63A, in particular at most 42A. This advantageous range of Shore hardness enables good properties with respect to axial rigidity of the catheter to be achieved.The invention is explained in more detail below on the basis of exemplary embodiments with reference to the attached representations. Shown therein are: FIG. 1 : a longitudinal section through an embodiment of a medical catheter according to the invention; FIG. 2 : Schematic illustration of a mandrel with spirally wound layers; FIG. 3 : a longitudinal section through the catheter according to FIG. 1, coils being additionally provided; FIG. 4 : a longitudinal section through the catheter according to FIG. 1, wherein balloon is additionally provided.FIG. 1 shows a longitudinal section of a medical catheter 10 for insertion into a hollow body organ with a distal section 11.The catheter 10 is adapted for inserting an implant, in particular a stent. The implant can be produced, for example, from a shape memory material.For example, catheter 10 is adapted for inserting and releasing stents, particularly self-expanding stents, particularly self-expanding stents made of shape memory materials.Suitable materials for the catheter 10 are plastics, metals, shape memory materials, such as nitinol, and radiovisible materials.The catheter 10 according to FIG. 1 comprises at least one feed channel 12.The delivery channel 12 is provided with a friction-reducing inner surface for a translatory movement of the stent in the delivery channel 12. Suitable materials for the inner surface include, for example, PTFE, FEP or HDPE or similar friction-reducing surface modifications. Other materials for the coating are also possible.The catheter 10 further comprises a liner 13 with an inner lumen 16. The liner 13 is formed as a layer 14 of the catheter 10 facing or delimiting the inner lumen 16 during use. The liner 13 may also be referred to as a liner or luminal inner layer of the catheter 10. In other words, the liner 13 is formed as the innermost layer of the catheter 10.It can be seen that the liner 13 extends along a longitudinal axis L over the entire length of the catheter 10. It is also conceivable that the liner 13 is limited only to partial sections of the catheter 10.According to FIG. 1, the wall thickness of the liner 13 in the distal section 11 is between 20% and 50% of the total wall thickness of the catheter in the distal section 11. With a wall thickness of the catheter 10 of 85 μm, the wall thickness of the liner 13 can be used, for example. 17 μm in order to achieve high flexibility of the catheter 10. In this case, the wall thickness of the liner 13 in the distal section 11 is 20% of the total wall thickness of the catheter. The effect of the liner 13 on the catheter properties is relatively slight, but perceptible. For example, the axial stiffness of the catheter is less affected by the liner 13 than by the remaining material of the catheter in the region of the catheter tip.If the wall thickness of the liner 13 is 17 μm with a wall thickness of the catheter 10 of 34 μm (50%), the influence of the liner 13 is particularly severe. The wall thickness of the liner 13 selected in this way has been shown to be particularly efficient in order to achieve good flexibility and high axial rigidity of the catheter 10 in the distal section 11. This allows the delivery of otherwise difficult implants.The catheter 10 of Figures 1, 2 and 3 further comprises a sheath 17. the sheath 17 forms a thin outer layer of the catheter 10.The liner 13 according to FIGS. 1, 2 and 3 has a plurality of layers 14. The layers 14 are arranged or stacked one above the other in the radial direction of the catheter 10.For forming the liner 13, FIG. 2 shows a mandrel 15.It should be noted at this point that, as shown in FIG. 2, the orientation of the layer 14 is merely an average or predominant orientation of the layer 14. It is possible that the number and the alignment of individual layers 14 deviate from the predefined alignment.The liner 13 according to FIGS. 1 to 4 has a wall thickness between 5 μm and 25 μm, in particular at most 23 μm, in particular at most 20 μm, in particular at most 19 μm, in particular at most 18 μm, in particular at most 17 μm, in particular at most 15 μm.In the exemplary embodiment according to FIG. 2, the liner 13 is formed from a fluorinated polymer (e.g. PTFE, PVDF), polyolefin (e.g. PP, PE), polyurethane (e.g. thermoplastic polyurethane (TPU), hydrophilic polyurethane), polyamide (e.g. PA6.6), polyester (e.g. PLA, PLGA, PET), polysulfone (e.g. PSU), polyetheretherketone (PEEK), biological and / or protein-based polymer. Other materials are conceivable.The catheter 10 has an inflation channel 18 according to FIG. 4. The inflation channel 18 is fluidly connected to a balloon 19. The inflation channel 18 is arranged next to the supply channel 12, in particular parallel. The liner 13 is formed as a layer facing an inner lumen 21 of the inflation channel 18. Thus, catheter 10 is suitable for insertion of balloon expandable stents.According to FIG. 4, the catheter 10 has a plurality of coils 20 which is arranged directly on an outer wall of the liner 13. The coils 20 are arranged longitudinally on the outer wall of the liner 13. It is possible that the number and the arrangement of individual coils 20 deviate from the predetermined arrangement and alignment according to FIG. 4. For example, the coils 20 can be arranged helically or helically on the outer wall of the liner 13.The jacket 17 is arranged on the coil 20 according to FIGS. 1, 2 and 3. The jacket 17 completely embeds the coil 20. It can be seen that the coils 20 are arranged next to one another and are completely embedded by the jacket 17.In the distal section 11, the jacket 17 has a Shore hardness of at most 25D, in particular at most 70A, in particular at most 63A, in particular at most 42A. In other words, the sheath 17 has a softer surface in the distal section 12.List of reference characters10 Medical catheter 11 Distal section 12 Supply channel 13 Liner 14 Layer 15 Mandrel 16 Inner lumen of the supply channel 17 Jacket 18 Inflation channel 19 Balloon 20 Coil 21 Inner lumen of the inflation channel L Longitudinal axisReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedUS 4516972 A [0001, 0002]US 2013 0 253 417 A1

[0006] US 2022 0 211 975 A1

[0007]

Claims

Medical catheter (10) for insertion into a hollow body organ having at least a proximal section and a distal section (11), wherein the catheter (10) comprises: - at least one feed channel (12) for feeding a medical implant; - a liner (13) which is formed by a spiral winding of a layer (14) onto a mandrel (15) and is formed as an inner layer of the catheter (10) facing an inner lumen (16) of the feed channel (12) in use; and - a jacket (17) which forms an outer layer of the catheter (10), characterized in that the wall thickness of the liner (13) in the distal section (12) is between 20% and 50% of the total wall thickness of the catheter (10), wherein the liner (13) comprises a plurality of layers (14) which are arranged one above the other in the radial direction of the catheter (10).Catheter (10) according to claim 1, characterised in that the liner (13) has a wall thickness between 5 μm and 25 μm, in particular at most 23 μm, in particular at most 20 μm, in particular at most 19 μm, in particular at most 18 μm, in particular at most 17 μm, in particular at most 15 μm.Catheter (10) according to claim 1 or 2, characterized in that the liner (13) is formed from a perfluorinated or partially fluorinated polymer (e.g. PTFE, PVDF), polyolefin (e.g. PP, PE), polyurethane (e.g. thermoplastic polyurethane, hydrophilic polyurethane), polyamide (e.g. PA6.6), polyester (e.g. PLA, PLGA, PET), polysulfone (e.g. PSU), polyetheretherketone (PEEK), biological and / or protein-based polymer.Catheter (10) according to one of the preceding claims, characterized in that the catheter (10) has an inflation channel (18) which is fluidically connected to a balloon (19) and is arranged next to the supply channel (12), in particular parallel, next to the supply channel (12), wherein the liner (13) is formed as a layer facing an inner lumen (21) of the inflation channel (18).Catheter (10) according to one of the preceding claims, in particular according to claim 4, characterized in that the catheter (10) has at least one coil (20) which is arranged, in particular directly, on an outer wall of the liner (13).Catheter (10) according to one of the preceding claims, in particular according to claim 5, characterized in that the coil (20) has a wire diameter between 15 μm and 55 μm, in particular at most 50.8 μm, in particular at most 38.1 μm, in particular at most 25.4 μm, in particular at most 19.05 μm.Catheter (10) according to one of the preceding claims, in particular according to Claim 6, characterized in that the coil (20) is formed from at least one wire, in particular two wires arranged in parallel, in particular three wires arranged in parallel, in particular four wires arranged in parallel.Catheter (10) according to one of the preceding claims, characterized in that the jacket (17) is arranged on the coil (20) and / or the jacket (17) embeds the coil (20), in particular completely.Catheter (10) according to one of the preceding claims, characterized in that the sheath (17) has a Shore hardness of at most 25D, in particular at most 70A, in particular at most 63A, in particular at most 42A, in the distal section (12).

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