Medical catheter for inserting into a hollow organ of the body

Abstract

The invention relates to a medical catheter (10) for inserting into a hollow organ of the body, having at least one proximal portion and a distal portion (11). The catheter (10) comprises the following: at least one supply channel (12) for supplying a medical implant; - a liner (13) which is formed by spirally winding a layer (14) onto a mandrel (15) and is designed as an inner layer of the catheter (10), said inner layer 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), wherein the wall thickness of the liner (13) in the distal portion (12) is between 20% and 50% of the total thickness of the catheter (10).

Description

[0001] Medical catheter for insertion into a hollow body organ

[0002] Description

[0003] The invention relates to a medical catheter for insertion into a hollow body organ according to the preamble of patent claim 1. A medical catheter of the type mentioned above is known, for example, from US 4516972 A.

[0004] US 4516972 A discloses a catheter for insertion into a cardiovascular system. A helically wound layer of a flexible material is embedded in a wall of the catheter to create axial stiffness of the catheter, which is intended to facilitate insertion into the cardiovascular system. This is intended to ensure that the catheter has sufficiently high stiffness and increased flexibility to be maneuverable in curved blood vessels.

[0005] Medical catheters, especially delivery catheters used to deliver stents, often face the problem that stents are becoming increasingly smaller and have a multitude of struts or wires, which can lead to increased friction during delivery within a catheter lumen. Particularly in the distal portion of the catheter, given the increasingly curved anatomy, this can lead to challenges regarding stretching and narrowing of the catheter lumen, which in turn can result in implantation jamming.

[0006] In general, catheters have different requirements. To enable access to small blood vessels and patency in highly curved vessels, a relatively high degree of flexibility is required. At the same time, the catheter should exhibit relatively high axial stiffness under axial pressure, i.e., when the catheter is pushed. Axial stiffness should also be ensured when the catheter is withdrawn or when an implant, such as a stent, is guided through the catheter to its intended destination.

[0007] In the known medical catheter, the contradiction between flexibility and axial stiffness of the catheter is supposed to be resolved by changing the pitch of the helically wound layer. A disadvantage of these catheters is that they have low axial stiffness and an excessively large overall wall thickness. This disadvantage is particularly evident when guiding the catheter through tight vessel bends.

[0008] The invention is therefore based on the object of specifying a catheter for insertion into a hollow body organ, which has good deliverability for medical implants.

[0009] According to the invention, this object is achieved by a medical catheter for insertion into a hollow body organ having the features of claim 1.

[0010] Specifically, this object is achieved by a medical catheter for insertion into a hollow body organ, comprising at least one proximal section and one distal section. The catheter comprises at least one delivery channel for delivering a medical implant, a liner formed by spirally winding a layer onto a mandrel and configured as an inner layer of the catheter facing an inner lumen of the delivery channel during use, and a sheath forming an outer layer of the catheter. The wall thickness of the liner in the distal section is between 20% and 50% of the total wall thickness of the catheter.

[0011] The invention has several advantages.

[0012] To increase the resistance to kinking of the catheter when it is moved within a patient's body, the catheter has two sections: a proximal section and a distal section. The proximal section is relatively stiff, and the distal section is relatively flexible. The distal section can be designed as a tip of the catheter. In a balloon catheter, a balloon is arranged in the distal section. Furthermore, the catheter has at least one delivery channel for delivering a medical implant. The delivery channel is designed as a through-channel and allows the implant to be guided to the treatment site.

[0013] In addition, the catheter has a liner formed by spirally winding a layer onto a mandrel and designed as an inner layer of the catheter facing an inner lumen of the delivery channel during use. This means that the entire liner is manufactured by spirally winding onto a mandrel. In other words, the liner is formed from the inside out, or from one side of the liner to the other, by spirally winding onto a mandrel. If the liner has multiple layers, all layers of the liner are formed by spiral winding. The entire wall thickness of the liner is formed from layers by spiral winding.

[0014] 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 a high degree of flexibility of the catheter in the distal section is achieved in this area. The ratio between the wall thickness of the liner and the wall thickness of the catheter in the distal section is adjusted such that the catheter in the distal section is flexible on the one hand and has sufficient axial rigidity on the other. This enables the insertion of otherwise stiff implants.

[0015] The wall thickness of the liner and the relative 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.

[0016] The larger the liner's proportion of the catheter's total wall thickness, the more the liner determines its properties. This affects, for example, its flexural rigidity and thus its flexibility. The closer the liner's proportion of wall thickness is to the upper limit of 50%, the more rigid the catheter is. Conversely, the liner's influence decreases the closer the proportion is to the lower limit of 20%.

[0017] It has been shown that in the range of 20% to 50% the influence of the liner on the properties of the catheter in the distal region, especially in the area of ​​the catheter tip, is particularly good.

[0018] The catheter tip is the distal end of the catheter, which is important for navigating the catheter in highly curved vessels. It is also where the implant exits the catheter during deployment. The catheter tip has a certain length, which can vary depending on the catheter. The length of the catheter tip corresponds to the distal section. The diameter of the catheter increases further proximally and is larger than in the area of ​​the catheter tip.

[0019] Preferred embodiments of the invention are specified in the subclaims.

[0020] The liner preferably comprises a plurality of layers arranged one above the other in the radial direction of the catheter. The individual layers can be arranged one above the other by spiral winding. Individual layers can be wound left- or right-handed onto 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 thin wall, especially compared to conventional liners. Furthermore, the multiple layers can be made of different materials. As a result, different layers can have different properties, such as different axial stiffness, elongation and / or flexibility.

[0021] The liner can have a wall thickness between 5 pm and 25 pm, in particular no more than 23 pm, in particular no more than 20 pm, in particular no more than 19 pm, in particular no more than 18 pm, in particular no more than 17 pm, in particular no more than 15 pm. Due to its low wall thickness, the liner exhibits high flexibility, which is particularly advantageous for use in curved blood vessels.

[0022] In a further preferred embodiment, the liner is made of 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, the polymer that has the desired properties for the respective area of ​​application can be selected from a multitude of polymers. Furthermore, different layers of the liner can be made of different polymers. For example, one layer can be made of PTFE, while another layer is made of PEEK. For example, the liner can be made of fluorinated polymers, such as PTFE, and / or of polymers that are provided with additives (compounds).This makes it possible, for example, to reduce the friction coefficient of the liner to achieve low-friction insertion of a medical implant. Such additives can be hydrophilic polymers, such as hydrophilic thermoplastic polymers (TPU), biopolymers, polyethylene glycol (PEG), and / or polyvinyl acetate (PVA).

[0023] The catheter may comprise only one inner lumen, which can be used to deliver a medical implant. Alternatively, the catheter may comprise multiple inner lumens or be designed as a multi-lumen catheter with multiple channels, with at least one liner being provided for each inner lumen or channel. Alternatively, only one channel or only some of the channels or inner lumens may have a liner.

[0024] The catheter preferably has an inflation channel that is fluidically connected to a balloon and is arranged next to the supply channel, in particular parallel to the supply channel. The liner can be designed as a layer facing an inner lumen of the inflation channel. The inflation channel is intended to fill the balloon with a fluid in order to expand the balloon, or to drain 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, e.g. air or NaCl, or a mixture thereof. The parallel arrangement of the channels increases the stiffness of the catheter. A liner that faces the inner lumen of the inflation channel can limit excessive 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.

[0025] 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 rigid material. In this case, the coil can be arranged in the longitudinal direction of the liner to increase the flexural rigidity of the liner in the longitudinal direction. Furthermore, the coil can be formed as a nickel-titanium wire, stainless steel wire, and / or wire made of another metallic material and can be arranged directly on an outer wall of the liner. The coils can thus influence the mechanical properties of the liner. Alternatively, multiple coils can be arranged on the outer wall.

[0026] The coil can have a wire diameter between 15 pm and 55 pm, in particular no more than 50.8 pm, in particular no more than 38.1 pm, in particular no more than 25.4 pm, in particular no more than 19.05 pm. The small diameter of the coil allows for use in microcatheter systems.

[0027] 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 arrangement of the wires results in a flat coil angle, thus achieving high flexibility of the catheter and high torque transmission. The coils are preferably formed by coiling the wire or by winding multiple wires on an outer wall of the liner. Alternatively, the coils can be formed by braiding multiple wires.

[0028] In a further preferred embodiment, the sheath is arranged on the coil and / or the sheath embeds the coil, in particular completely. Preferably, the sheath is made of a plastic material. Such materials have high extensibility and are easy to manufacture, for example, by an electrospinning process. The plastic material enables the production of a particularly thin and fine-pored sheath. Furthermore, the plastic material inherently exhibits a high degree of flexibility, thus achieving a high degree of flexibility of the catheter.

[0029] Preferably, the sheath in the distal section has a Shore hardness 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 allows good properties regarding the axial stiffness of the catheter to be achieved.

[0030] The invention is explained in more detail below using exemplary embodiments with reference to the attached illustrations. In these illustrations:

[0031] Fig. 1: a longitudinal section through an inventive

[0032] Example of a medical catheter;

[0033] Fig. 2: schematic illustration of a mandrel with spirally wound layers;

[0034] Fig. 3: a longitudinal section through the catheter according to Fig. 1, with additional coils being provided;

[0035] Fig. 4: a longitudinal section through the catheter according to Fig. 1, with an additional balloon provided.

[0036] Fig. 1 shows a longitudinal section of a medical catheter 10 for insertion into a hollow body organ with a distal section 11.

[0037] The catheter 10 is adapted for the introduction of an implant, in particular a stent. The implant can be made, for example, of a shape-memory material.

[0038] For example, the catheter 10 is adapted for the introduction and deployment of stents, particularly self-expanding stents, particularly self-expanding stents made of shape-memory materials. Suitable materials for the catheter 10 include plastics, metals, shape-memory materials such as nitinol, and radiopaque materials.

[0039] The catheter 10 according to Fig. 1 comprises at least one supply channel 12. The supply channel 12 is designed to supply an implant.

[0040] The delivery channel 12 is provided with a friction-reducing inner surface to facilitate translational movement of the stent within the delivery channel 12. Suitable materials for the inner surface include PTFE, FEP, or HDPE, or similar friction-reducing surface modifications. Other materials for the coating are also possible.

[0041] The catheter 10 further comprises a liner 13 with an inner lumen 16. The liner 13 is configured as a layer 14 of the catheter 10 that, during use, faces or borders the inner lumen 16. The liner 13 may also be referred to as the lining or luminal inner layer of the catheter 10. In other words, the liner 13 is configured as the innermost layer of the catheter 10.

[0042] 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 to only partial sections of the catheter 10.

[0043] 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. The wall thickness of the liner 13 in the distal section 11 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. With a wall thickness of the catheter 10 of 85 μm, the wall thickness of the liner 13 can be, 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 influence of the liner 13 on the catheter properties is relatively small, but noticeable. For example, the axial stiffness of the catheter is influenced less by the liner 13 than by the remaining material of the catheter in the area of ​​the catheter tip.If the wall thickness of liner 13 is 17 μm with a wall thickness of catheter 10 of 34 μm (50%), the influence of liner 13 is particularly strong. This selected wall thickness of liner 13 has proven particularly effective in achieving good flexibility and high axial stiffness of catheter 10 in the distal section 11. This enables the insertion of otherwise stiff implants.

[0044] The catheter 10 according to Figs. 1, 2 and 3 further comprises a sheath 17. The sheath 17 forms a thin outer layer of the catheter 10.

[0045] The liner 13 according to Figs. 1, 2, and 3 has several layers 14. The layers 14 are arranged or stacked one above the other in the radial direction of the catheter 10.

[0046] To form the liner 13, Fig. 2 shows a mandrel 15. At least one layer 14 is wound spirally on the mandrel 15 to form the liner 13.

[0047] At this point, it should be noted that the orientation of layer 14 shown in Fig. 2 is merely an average or predominant orientation of layer 14. It is possible that the number and orientation of individual layers 14 may deviate from the specified orientation.

[0048] The liner 13 according to Fig. 1 to 4 has a wall thickness between 5 pm and 25 pm, in particular at most 23 pm, in particular at most 20 pm, in particular at most 19 pm, in particular at most 18 pm, in particular at most 17 pm, in particular at most 15 pm.

[0049] In the embodiment according to Fig. 2, the liner 13 is made of 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 fluidically connected to a balloon 19. The inflation channel 18 is arranged next to the supply channel 12, in particular parallel. The liner 13 is designed as a layer facing an inner lumen 21 of the inflation channel 18. The catheter 10 is therefore suitable for introducing balloon-expandable stents.

[0050] According to Fig. 4, the catheter 10 has a plurality of coils 20 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 arrangement of individual coils 20 may deviate from the predetermined arrangement and orientation shown in Fig. 4. For example, the coils 20 may be arranged helically or helically on the outer wall of the liner 13.

[0051] The casing 17 is arranged on the coil 20 as shown in Figs. 1, 2, and 3. The casing 17 completely embeds the coil 20. It can be seen that the coils 20 are arranged side by side and completely embedded by the casing 17.

[0052] The casing 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 11. In other words, the casing 17 has a softer surface in the distal section 12.

[0053] Reference symbol list

[0054] 10 Medical catheter

[0055] 11 Distal section

[0056] 12 feed channel

[0057] 13 liners

[0058] 14 shift

[0059] 15 Mandrel

[0060] 16 inner lumen of the supply channel

[0061] 17 Coat

[0062] 18 Inflation channel 19 Balloon

[0063] 20 coils

[0064] 21 inner lumen of the inflation channel

[0065] L Longitudinal axis

Claims

Claims 1. 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 sheath (17) forming 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).

2. Catheter (10) according to claim 1, characterized in that the liner (13) comprises several layers (14) which are arranged one above the other in the radial direction of the catheter (10).

3. Catheter (10) according to claim 1, characterized in that the liner (13) has a wall thickness between 5 pm and 25 pm, in particular at most 23 pm, in particular at most 20 pm, in particular at most 19 pm, in particular at most 18 pm, in particular at most 17 pm, in particular at most 15 pm.

4. Catheter (10) according to one of the preceding claims, 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.

5. 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 designed as a layer facing an inner lumen (21) of the inflation channel (18).

6. Catheter (10) according to one of the preceding claims, in particular according to claim 5, 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).

7. Catheter (10) according to one of the preceding claims, in particular according to claim 6, characterized in that the coil (20) has a wire diameter between 15 pm and 55 pm, in particular at most 50.8 pm, in particular at most 38.1 pm, in particular at most 25.4 pm, in particular at most 19.05 pm.

8. Catheter (10) according to one of the preceding claims, in particular according to claim 7, 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.

9. Catheter (10) according to one of the preceding claims, characterized in that the sheath (17) is arranged on the coil (20) and / or the sheath (17) embeds the coil (20), in particular completely.

10. Catheter (10) according to one of the preceding claims, characterized in that the sheath (17) in the distal section (12) has a Shore hardness of at most 25D, in particular not more than 70A, in particular not more than 63A, in particular not more than 42A.

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