Shaft for a catheter and manufacturing method

Abstract

To provide a shaft for a catheter which has a tubular core which may be usable with a minimally invasive procedure such as intravascular medical treatment system, the shaft having different flexural properties determined by the stiffness of zones, and also to provide a method of fabricating such a shaft.SOLUTION: A shaft 100 has a longitudinal axis L defining a radial distance, and a cross section C having a polar axis ρ defining an angular position φ. The shaft 100 comprises: a tubular core 102 which has an inner perimeter 104 and an outer perimeter 106; and an outer layer 112 for improving mechanical properties, which encloses the tubular core 102 such that the outer perimeter 106 of the core 102 and the outer layer 112 face each other. The radial distance between the outer perimeter 106 and the inner perimeter 104 differs at different polar angular positions φ, forming zones of different stiffness at different angular positions φ. Different planes of the shaft oriented along the longitudinal axis L and cutting the cross section C at different polar angular positions φ have different flexural properties which are determined by the stiffness of the zones.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a shaft for a catheter having a tubular core that may be used in minimally invasive procedures such as endovascular therapy systems. The present invention also relates to a method of manufacturing such a shaft.

Background Art

[0002] Endovascular medical procedures enable treatment at various locations within a patient's body while requiring only relatively small access incisions. For example, endovascular procedures may eliminate the need for open chest surgery and reduce the risks, costs, and time associated with open chest procedures. Endovascular procedures have low associated costs and risks of complications and also allow for a rapid recovery time. Examples of endovascular procedures that significantly reduce procedure, recovery time, and costs compared to conventional open surgery include cardiac valve replacement or repair procedures in which an artificial valve or valve repair device is guided through a patient's vasculature to the heart. For example, a catheter is inserted into a patient's vasculature and directed toward the inferior vena cava. The catheter is then urged through the inferior vena cava into the heart by applying force axially along the catheter. As soon as the catheter enters the heart from the inferior vena cava, the catheter enters the right atrium. The distal end of the catheter may be deflected by one or more deflection mechanisms, which may be achieved by a tension cable or other mechanism disposed within the catheter. Precise control of the distal end of the catheter enables more reliable and rapid placement of medical devices and / or implants and other improvements in the procedure. Apart from applications to structural heart disease, catheters are also used in minimally invasive procedures such as gastrointestinal applications or neurovascular, coronary artery, structural heart disease, peripheral vascular, or endoscopic-type procedures for other applications.

[0003] Since it is difficult to reposition a medical device after it has been fully deployed from a delivery system, an intravascular delivery device needs to be accurately positioned to ensure correct positioning of the medical device, and correct positioning is essential for the functionality of the medical device. In addition, the catheter needs to have the ability to convert or rotate the distal end of the catheter, similar to the movement of the proximal portion, i.e., the catheter handle. This is achieved by torque transmission along the longitudinal direction of the shaft. For example, it is maneuvered only once to overcome anatomically difficult locations. At the same time, the catheter needs to be such that portions of the catheter can be moved independently of the rest of the catheter. The design of the catheter shaft is an important factor in determining the formation of curves, the angle of deflection, and the degree of maneuverability. The choice of material determines the degree of pushability, torque, and flexibility and can be manipulated along the longitudinal direction of the catheter in various ways to achieve the desired results.

[0004] The catheter shaft needs to be accurately positioned to ensure correct positioning of the medical device. Multiple lumens are created within the catheter for guidewires, catheters, fluids, and gas passages. The number of lumens depends on the material and the cross-sectional area. The lumens can be formed to meet the user's requirements. Reinforcing rods and pull wires may be inserted into the lumens. FIG. 16 shows a conventional multi-lumen catheter configuration with two wires disposed in the lumens.

[0005] For upward torque performance and deflection, it is known to use single or multi-lumen shafts, and braided layers, wound layers, or other layers disposed on the shafts. Reinforcing bars and pull wires may be installed in place during the braiding process. Due to the lack of symmetry of the reinforcing braided layer due to the varying thickness of the wire height, the result is often suboptimal longitudinal torque performance of the catheter shaft and often insufficient torque performance. In addition, problems may occur during fabrication regarding integrating the reinforcement or pull wires within the lumen, and furthermore, a complex braiding configuration has to be provided for additional braided layers, thus increasing the manufacturing cost.

Summary of the Invention

Problems to be Solved by the Invention

[0006] There is still a need for a shaft with improved mechanical properties while improving the manufacturing method and production cost.

Means for Solving the Problems

[0007] This object is solved by the subject matter of the independent claims. Advantageous embodiments of the invention are the subject matter of the dependent claims.

[0008] The present invention is based on the idea that by providing a tubular core (sometimes also referred to as a "liner") for a shaft having sections of different radial distances between the inner and outer circumferences of the core, the bending characteristics of different longitudinal planes of the shaft, i.e., in other words, the cross-sectional second moment of inertia of the shaft with respect to different axes, can be improved.

[0009] In particular, the present invention has a cross-section having a longitudinal axis defining a radial distance and a polar axis defining an angular position, a tubular core having the cross-section with an inner circumference and an outer circumference, and an outer layer for torsional resistance or torque transmission, the outer layer surrounding the tubular core such that the outer circumference of the tubular core faces the outer layer, the radial distance between the outer circumference and the inner circumference being different at different polar angular positions, forming sections of different stiffness, and different planes of the shaft, which are oriented along the longitudinal axis and cut the cross-section at different angular positions, having different bending characteristics determined by the stiffness of the sections, provides a shaft for a catheter.

[0010] For example, the bending characteristics include strengths such as bending strength in tension, compression resistance, and / or torsional resistance.

[0011] This solution has the advantage that a shaft including an outer layer for torsional resistance or torque transmission, by selecting different radial distances between the outer and inner circumferences of the core at different polar angular positions, obtains different planes having different bending characteristics that cut the cross-section at different angular positions. In other words, the specific cross-sectional second moment of the shaft with respect to different axes can be obtained by changing the radial distance between the outer and inner circumferences. Additionally, maintaining a form of symmetric braiding near the outer surface of the shaft provides the advantage of significantly increased torque performance.

[0012] The shaft can be easily bent about an axis perpendicular to a longitudinal plane (the longitudinal plane includes the longitudinal axis) that cuts through a section of low stiffness, in which case the section of low stiffness undergoes the greatest deformation, such as the highest compression and tension, while the section of high stiffness maintains the neutral axis. It is more difficult for the shaft to be bent about an axis perpendicular to a plane that includes a section of high stiffness. This is because, in this case, the section of high stiffness is the section that undergoes the greatest deformation. For example, advantageously, out-of-plane stiffness is increased to stably position the shaft in anatomical cavities such as the atrium, ventricle, IVC, or other regions, which are anatomical regions where additional stability is required during percutaneous medical interventions.

[0013] Another advantage is that in the distal sections, column strength is added, and in these distal sections, the flexible soft durometer material is limited to the sections required, for example, for the deflection of one plane.

[0014] Advantageously, the sections of different stiffnesses are not enclosed between the inner diameter and the outer diameter (as in multi-lumen extrusion), so the sections do not impose constraints on the minimum core thickness.

[0015] A further advantage is that the sections of different stiffnesses are created by changing the radial distances of the outer and inner circumferences, which allows the use of many combinations of geometry and polymer. This avoids the need to create a lumen extending in the longitudinal direction of the tubular core. Furthermore, creating the sections by changing the radial distance between the outer diameter and the inner diameter facilitates the related manufacturing.

[0016] Therefore, the present invention is advantageous in terms of optimizing the geometry of the core, for example, to obtain a desired second moment of cross-section with respect to different axes. The second moment of cross-section, i.e., the tubular body, strongly depends on the radial distance between the outer and inner circumferences with respect to the longitudinal axis at different angular positions, and particularly strongly depends on the radial distance of the outer circumference. For this reason, the geometry of the individual core of the present invention is advantageous in that it provides a significant change in the second moment of cross-section (with respect to a certain axis) when the radial distance of the outer or inner circumference, or the difference between them, is changed.

[0017] In the example shown, the cross-sections of the core along the longitudinal axis are all the same, i.e., the radial distance between the inner and outer circumferences at a certain angular position is the same in all cross-sections along the longitudinal axis. However, it is obvious to those skilled in the art that the radial distance between the inner and outer circumferences at a certain angular position may be different in different cross-sections along the longitudinal axis.

[0018] It is also possible for the shaft to have other solid shapes different from the tubular shape.

[0019] The present invention is also based on the idea that the low-rigidity section is formed by grooves made on the outer surface of the core in which the reinforcing wire and the pull wire can be arranged. The grooves are formed along one or more generatrices of the core and remain exposed to the outer layer, so that the thermoplastic polymer penetrates into the grooves together with the wire and the outer layer, creating a bond between the wire and the outer layer that serves as additional structural binding with improved load distribution. The polymeric material may penetrate the outer coating and strengthen the wire and the reflow wall.

[0020] According to an advantageous embodiment of the invention, the thin-section is formed by a groove on the outer periphery of the tubular core extending along the longitudinal axis of the tubular core. This has the advantage that an extruded product having grooves, for example made of PTFE, has good integrity and does not require stretch down before the braiding process. For example, the thin-section may be formed as a groove extruded on the outer periphery along the longitudinal axis (along one or more generatrices). Preferably, the groove is of a concave shape such as circular or elliptical. The groove may have a square or any other cross-sectional shape.

[0021] The groove can be arranged on a core mandrel that is 0.0005 - 0.001” (0.0127 - 0.0254 mm) smaller than the inner diameter. The groove can be held by a temporary mechanical lock to the core mandrel to prevent any relative twist on the core mandrel. The currently drawn liner with a thickness of 0.0015” (0.0381 mm) can rotate further relative to the core mandrel surface if the tension / stretch of the liner is insufficient.

[0022] This arrangement also has the advantage of a simpler outer layer configuration. With this arrangement, it is also possible to place the wires in the grooves when the shaft is inserted into the braid, and there is no need to insert round or flat wires through a round surface (the wires are placed in the exposed area of the grooves), thus eliminating the possibility of wire slip and torsion. Further, due to the fact that the grooves are back-coated by the PTFE wall with a minimum thickness between the inner lumen and the pull wire lumen, skiving for inserting the inlet and outlet of the pull wire is less likely to cause damage and potential leakage points.

[0023] According to an advantageous embodiment of the invention, at least two sections with a thin thickness are arranged at polar angle positions 180° apart from each other. This arrangement is advantageous in that the rigidity of the shaft is low with respect to an axis perpendicular to the plane cutting the generatrix where the two sections with a thin thickness are arranged. At the same time, the rigidity of the shaft is high with respect to an axis parallel to the plane cutting the generatrix where the low-rigidity section is arranged. With this configuration, the shaft has two main rigidity planes. For example, the plane with the highest rigidity may be used for the stable arrangement of the shaft in anatomical cavities such as the atrium, ventricle, IVC or other anatomical regions where additional stability is required during percutaneous therapeutic intervention.

[0024] Another advantage is that the core can take many geometric shapes to accommodate the wires necessary for shaft manipulation and reinforcement. For example, the core may have four sections with a thin thickness arranged at angular positions 90° apart from each other. Alternatively, it may have eight sections with a thin thickness arranged at angular positions 45° apart from each other. For example, the core may have sections with a thin thickness arranged at asymmetric angular positions.

[0025] According to an advantageous embodiment of the invention, the outer layer comprises a braided layer, a wound layer, or other reinforcing layer. This has the advantage of improved torque performance when the symmetry of the braid is well maintained, and is less likely to be subject to the so-called whip effect that may occur in a standard configuration when there are significant differences in outer diameter and rigidity between planes.

[0026] According to an advantageous embodiment of the invention, at least one reinforcing wire is arranged in one or more thin-thickness sections. This arrangement has the advantage that the rigidity of the shaft is increased with respect to an axis perpendicular to the plane that cuts the longitudinal axis of the core and the generatrix on which the reinforcing wire is arranged. This is because of the fact that the wire has a high modulus of elasticity. Advantageously, the rigidity of one or more planes with low rigidity (low moment of inertia of the cross-section) due to their geometry is increased by using a material with a high modulus of elasticity such as iron. Therefore, the rigidity of different planes of the core can be adjusted more precisely and accurately, thanks to simultaneously obtaining the advantages of the geometric characteristics of the core (e.g., the moment of inertia of its cross-section) and the selection of the modulus of elasticity of the materials used (these are two factors that affect the rigidity of the core in a certain plane). Many combinations of the geometry of the polymer and the metal wire can be used to establish an operation specific to the design. For example, the wire can be a single or double flat or round wire. This arrangement allows the out-of-plane rigidity to be increased for a stable arrangement of the shaft in anatomical regions where additional stability is required during percutaneous medical interventions. If necessary, the wire can have a round shape to reduce the compression of the shaft. Furthermore, the fact that the wire is arranged in a thin-thickness section formed by a groove on the outer periphery of the core has the advantage that the wire remains exposed to the outer layer and faces the outer layer.

[0027] The reinforcing wire preferably consists of a material with a high modulus of elasticity, for example a high Young's modulus, in order to increase the required rigidity when deflection is not desired. For example, iron is one of the preferred low-cost materials for the wire. Other materials such as carbon fiber, polymer fiber, or other metal fibers such as nitinol may be used if applicable to a certain operation.

[0028] According to an advantageous embodiment of the invention, at least one pull wire is arranged in one or more thin - thickness sections for steering. This arrangement has the advantage that one or more steered planes can be obtained. This arrangement also has the advantage that the pull wire can be arranged in the same thin - thickness section as a reinforcing wire or in different sections. In addition, the pull wire remains exposed to the outer layer and faces the outer layer.

[0029] According to an advantageous embodiment of the invention, the shaft further comprises an outer coating surrounding the outer layer. In this arrangement, there is the advantage that additional protection and mechanical stability are provided for the shaft.

[0030] According to an advantageous embodiment of the invention, the outer coating comprises a polymeric material that at least partially penetrates the outer layer and the thin - thickness section. The polymeric material is preferably a thermoplastic polymeric material, i.e., it becomes flexible above a certain temperature, i.e., it can be molded, and solidifies upon cooling. In this arrangement, there is the advantage that the polymeric material provides a secure bond between the reinforcing bars arranged in the grooves, the outer layer, and the outer coating.

[0031] For example, when a reinforcing wire is arranged in a thin - thickness section, the composite material comprising the wire, the outer layer, the polymer, and the coating has a high tensile strength due to the wire and high resistance to compression, bending, and other stresses. When the thermoplastic polymer formed by a reflow or coating process that at least partially penetrates the outer layer and the thin - thickness section solidifies, the thermoplastic polymer adapts to the surface of the wire and forms a single structure that enables any stress to be efficiently transmitted between different materials.

[0032] To further improve the bundling or bonding between the thermoplastic material and the wire, the wire and the outer layer may be coated, roughened, and corrugated. The pull wire is housed in a separate liner to facilitate replacement with a thin - type pull wire used in the final assembled device, so the pull wire will operate in a groove filled with the thermoplastic material.

[0033] The present invention further relates to the assembly of a catheter comprising a shaft according to the previous embodiment.

[0034] The present invention further relates to a corresponding method for manufacturing a shaft for a catheter, the method comprising forming a tubular core having a cross-section including an inner circumference and an outer circumference; forming sections of different stiffness at different angular positions of the tubular core, the step of having different radial distances between the outer and inner circumferences at different polar angular positions; forming an outer layer surrounding the tubular core such that the outer circumference of the core and the outer layer face each other in order to improve mechanical properties; and comprising.

[0035] Advantageously, by the method of defining different radial distances between the outer and inner circumferences at different polar angular positions, the step of forming sections of different stiffness at different angular positions avoids the limitation of the minimum thickness of the core resulting from the extruded lumen shaft.

[0036] Furthermore, for torsional resistance and / or torque transmission, the step of forming an outer layer surrounding the tubular core such that the outer circumference of the core and the outer layer face each other is advantageous in that it provides a simpler outer layer configuration while improving the close fitting of the outer layer to the thin thickness sections of the core.

[0037] According to another embodiment, the method comprises the step of forming a thin-thickness section formed by a groove on the outer periphery of a tubular core extending along the longitudinal axis of the tubular core. Advantageously, extrusion with grooves of materials such as PTFE has good maintainability and does not require stretch-down prior to the process of forming the outer layer. The core can be placed on a core mandrel that is 0.0005 - 0.001” (0.0127 - 0.0254mm) smaller than the inner diameter. The core can be held by temporary mechanical fixation to prevent any twisting on the core mandrel. Generally, a stretch liner with a thickness of 0.0015” (0.0381mm) can be further wound around the core mandrel surface. Furthermore, the stretching process of the liner can also cause unexpected effects due to excessive or insufficient stretching.

[0038] According to another embodiment, the method comprises the step of incorporating at least one reinforcing wire and / or at least one pull wire into the thin-thickness section. Advantageously, the fact that the thin-thickness section is formed on the outer periphery, preferably by extrusion with grooves, ensures that when the shaft is inserted into the braid, the wire is placed in the groove, and the possibility of wire slip and twist is eliminated because round or flat wires are not inserted into the round surface. It has a great effect in facilitating the end-to-end straight wire configuration, which can be difficult and cause batch-to-batch variations. Furthermore, due to the fact that the groove is back-coated with a wall thinner than the conventional 0.0015” (0.0381mm) PTFE liner, skiving for inserting the inlet and outlet of the pull wire is less likely to cause damage and potential leakage or weak points.

[0039] For example, one or more reinforcing wires can be joined in one or more grooves, which is advantageous in obtaining different planes with different bending characteristics. The pull wire can be joined to one or more grooves to achieve steering in different directions. For example, single-direction steering may be used to overcome a single anatomical difficulty. Two-direction or multi-direction steering may be used to assist in overcoming multiple anatomical difficulties.

[0040] According to other embodiments, before or during the formation of the outer layer, the step of incorporating at least one reinforcing wire and / or at least one pull wire into a thin-thickness section is performed. This eliminates the need to insert the wire longitudinally into the long lumen, thereby eliminating the possibility of core damage.

[0041] According to other embodiments, the method comprises the step of adding an outer coating to protect and stabilize the shaft.

[0042] According to other embodiments, the method further comprises the step of bonding a polymer material formed by a reflow or coating process that at least partially penetrates the outer layer and the thin-thickness section. This step is advantageous in that by bonding a thermoplastic polymer material that solidifies preferably by temperature, an efficient and low-cost method is provided to achieve a secure (strong) bond between the reinforcing bars placed in the grooves, the outer layer, and the outer coating. For example, when the reinforcing wire is placed in the thin-thickness section, the composite material comprising the wire, the outer layer, the polymer material, and the coating has a high tensile strength due to the wire and also has a high resistance to compression, bending, and other stresses or torsions. When the thermoplastic polymer formed by a reflow or coating process that at least partially penetrates the outer layer and the thin-thickness section is solidified, the thermoplastic polymer adapts to the surface of the wire, enabling any stress to be efficiently transmitted between different materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying figures, which are incorporated in and form a part of this specification, illustrate several embodiments of the invention and, together with the description, serve to explain the principles of the invention. These figures are only for the purpose of illustrating preferred and alternative examples of how the invention may be made and used, and are not to be construed as limiting the invention to only the illustrated and described embodiments. Further, multiple aspects of the embodiments may form solutions according to the invention separately or in different combinations. Accordingly, the embodiments described below may be considered either individually or in any combination. As will be described in the more specific descriptions of the various embodiments of the invention shown below, along with the accompanying drawings where like references refer to like elements, further features and advantages will become apparent.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Mode for Carrying Out the Invention

[0044] The present invention will hereinafter be described in detail by reference to these figures, and first reference is made to FIG. 1.

[0045] FIG. 1 is a schematic cross-sectional depiction of a shaft 100 assembly according to a first embodiment of the present invention. The shaft 100 has a tubular shape. The shaft 100 has a longitudinal axis L that defines a radial distance, which is the distance from the longitudinal axis L to a point contained in a plane perpendicular to the longitudinal axis L. In this figure, the longitudinal axis is perpendicular to the plane of the paper. The cross-section C of the shaft as used herein is defined as a cross-section or plane perpendicular to the longitudinal axis L of the shaft 100. The cross-section C has a polar axis ρ, and the polar axis ρ can be used to define a polar angle position φ that is defined as an angular distance to the polar axis.

[0046] The shaft has a tubular core 102 having an inner circumference 104 and an outer circumference 106, and the inner and outer circumferences define the cross-section of the core. The outer circumference has a greater radial distance from the longitudinal axis than the inner circumference. The radial distance d between the inner circumference 102 and the outer circumference 104 is the difference between the radial distance of the outer circumference 106 and the radial distance of the inner circumference 104. The radial distance between the outer and inner circumferences varies at different polar angle positions φ, and as a result, different stiffness sections 108, 110 are formed. The word "stiffness" as used herein means the degree to which an object resists deformation as a reaction to an applied force. Stiffness is a quantity characteristic of a solid that depends on the material, shape, and boundary conditions, and may include axial stiffness or torsional stiffness.

[0047] For example, the thickness of the section can be defined as the average value of the radial distance between the outer circumference 106 and the inner circumference 104 at a given polar angle distance (Δφ). The section 108 is defined as an angular section of the core where the wall thickness of the core changes so as to cause a significant change in the rigidity of the core 102. FIG. 1 shows a core including two low-rigidity sections 108, 110, and each section has a significant impact on the cross-sectional moment of inertia of the core. The two sections 108, 110 are 180° apart from each other. The section 108 is located at an angular position of 90° with respect to the ρ axis. The section 110 is located at an angular position of 270° with respect to the ρ axis. The vertical arrow 116 indicates the direction of the plane of high flexibility on the cross-section, and the plane of high flexibility coincides with the plane that cuts the two low-rigidity sections 108, 110 perpendicular to the plane of the cross-section. In other words, the plane of high flexibility coincides with the plane that cuts the generatrix including each thin-thickness section 108, 110. The plane indicated by the arrow 118 is a plane of high rigidity. The expression "a plane that cuts the two low-rigidity sections perpendicular to the plane of the cross-section" refers to the plane that cuts the two low-rigidity sections and includes the longitudinal axis. The expression "a plane of the shaft oriented along the longitudinal axis" refers to a plane that includes the longitudinal axis.

[0048] The term "generatrix" refers to a straight line included in the outer surface of the core and parallel to the longitudinal axis (the straight line is one side of a rectangle that forms a cylindrical shape of the outer surface of the core when the rectangle rotates around one side of the rectangle that coincides with the axis of the core). When the shaft is bent with respect to an axis perpendicular to the flexible plane, the low-rigidity section undergoes the highest deformation, for example, the highest compression and tension, while the high-rigidity section remains at the neutral axis. The horizontal arrow 118 indicates the direction of the plane of high rigidity, which is perpendicular to the plane of high flexibility in FIG. 1.

[0049] When the high-rigidity section undergoes the highest tension and compression, while the low-rigidity section remains at the neutral axis, the shaft 100 is difficult to bend with respect to an axis perpendicular to the plane of high rigidity.

[0050] The shaft 100 includes an outer layer 112 for improving mechanical properties such as tensile compression, flexibility, torsional resistance, and torque transmission. The outer layer 112 surrounds the tubular core 102 such that the outer periphery 106 of the tubular core and the outer layer 112 face each other. The shaft may further include an outer coating 114 that surrounds the outer layer 112 and the tubular core 102.

[0051] As illustrated in FIG. 1, the thin-thickness section may have the shape of a concave meniscus (106, 108) or a groove formed on the outer diameter, so that the meniscus (groove) faces the outer layer. The thin-thickness section may have other shapes, such as a more circular meniscus, an angular (polygonal) shape, or any other shape that improves mechanical properties. The thin-thickness section extends along the longitudinal axis L of the tubular core.

[0052] FIG. 2 is a schematic side view of a shaft according to another embodiment of the present invention. This figure shows a part of the outer surface of the core and coincides with the outer diameter. This figure shows the outer layer which is a braided layer. The outer surface of the core is exposed to the outer layer and the outer coating. The outer coating 114 surrounds the outer layer and the core. The outer coating is made of, for example, a polymer material that penetrates the outer layer and the thin-thickness section.

[0053] Figure 3 is a schematic depiction of the configuration of the first shape of the shaft. This figure shows a deflectable shaft including a tip that forms a predetermined curve. This may be used in very angled transitions in distal anatomical structures, i.e., may be used to control the exact position of the tip of the catheter. The curve angle can be adjusted to a preferred angle for a given operation ranging from 0° to 360° depending on the operation. The curve of the shaft depends on the rigidity of the shaft with respect to an axis perpendicular to the plane in which the shaft is bent, among other factors. The low-rigidity sections are maintained for the inner and outer curves, while the high-rigidity sections are maintained for the neutral axis. The angle of curvature can vary. The deflection curve may be a single-plane deflection curve in which the shaft deflects about one axis, or a two-plane deflection curve (a catheter deflectable in four directions, turning front-back and left-right), i.e., an out-of-plane deflection, in which the tip of the catheter deflects about two axes. The bend, i.e., the length of the deflected portion of the shaft with respect to the diameter of the curve, may be short, intermediate, or long, and the bend, i.e., the length, depends on the rigidity of the catheter with respect to different axes, i.e., the shape and polar angle position of the thin-thickness (groove) section, and the position of the reinforcing bar. The length of the deflectable portion of the catheter, i.e., the curvature, may take different values.

[0054] Figure 4 is a schematic depiction of the configuration of the second shape of the shaft. In this figure, the shaft has two deflection points along its length. As shown in Figure 4, the shaft deflects, for example, in an S shape.

[0055] Figure 5 is a schematic depiction of the configuration of the third shape of the shaft.

[0056] FIG. 6 is a cross-sectional view of a shaft assembly according to another embodiment of the present invention. The figure shows a shaft including four thin sections 120, 122, 124, 126. The four thin sections are located at pole angle positions 90° apart from each other. The thin section 120 is arranged at a pole angle φ1 of 0° with respect to the pole angle axis. The section 122 is arranged at a pole angle φ2 of 90° with respect to the pole axis ρ. The section 124 is arranged at a pole angle φ3 of 180° with respect to the axis ρ. The thin section 126 is arranged at a pole angle φ4 of 270°. There are two reinforcing wires 128, 129 in the thin section 120, and two reinforcing wires 130, 131 in the thin section 124. The sections 120 and 124 have pole angle positions 180° apart from each other. Due to the fact that the wires 128, 129, 130, 131 are made of a material with a high elastic modulus, the reinforcing wires 128, 129, 130, 131 change the rigidity of the thin sections 120 and 124 and stiffen them. Therefore, the shaft of FIG. 6 has a high-rigidity plane 134 that cuts the thin sections 120 and 124 (having the reinforcing wires 128, 129, 130, 131) perpendicular to the cross-section C. The highly flexible plane 132 cuts the thin sections 126 and 122 perpendicular to the plane of the cross-section C.

[0057] As used herein, the expression "plane that cuts a thin section" means that the plane divides the thin section perpendicular to the plane of the cross-section. (It is also possible for the expression to mean that the plane divides the thin section and includes the longitudinal axis.) In FIG. 6, the four reinforcing wires are formed in a circular shape and occupy only the central portions of the thin sections 120 and 124. However, the wires may have different shapes and sizes. In FIG. 6, the thin sections 120, 122, 124, 126 have the same shape, which is a concave meniscus (groove) on the outer diameter. However, the thin sections may have different shapes.

[0058] Figure 7 is a schematic depiction of a portion of the shaft of FIG. 6. This figure shows thin thickness sections 120 and 122 extending along two generatrices of the core. Thin thickness sections 124 and 126 are also partially shown, extending along two other generatrices. In this exemplary embodiment, the thin thickness sections 120, 124, 122, 126 are formed as grooves (or concave menisci) parallel to the longitudinal axis on the outer surface of the core. Wires 128, 129 are disposed in the thin thickness section 120, and wires 130 and 131 are disposed in the thin thickness section 124. Figure 7 shows that the outer surface of the core 102 faces the outer layer 112 and is exposed to the outer layer 112. The outer layer 112 is a braided layer that surrounds the core. The thin thickness sections 120, 124, 122, 126 formed on the outer surface of the core also face the outer layer 112. The outer coating 114 surrounds the outer layer and the core. Therefore, the thin thickness sections 120, 124, 122, 126 are also exposed to the outer coating.

[0059] Figure 8 is a cross-sectional view of a shaft assembly according to another embodiment of the present invention. This figure shows a plane 136 having high flexibility that cuts the thin thickness sections 140, 142 perpendicular to the cross-section C. Two pull wires 144, 146 are respectively disposed in the thin thickness sections 140, 142. The pull wires are disposed for steering. The tip can be pulled in two opposite directions for bidirectional steering. The outer layer 112 is disposed near the outer surface of the core and is therefore disposed near the thin thickness sections 140, 142. The symmetry of the outer layer 112 is maintained to improve performance. The plane indicated by the arrow 138 is a plane of high rigidity and is perpendicular to the plane 136 having high flexibility.

[0060] Figure 9 is a side view of a portion of the shaft of FIG. 8. This figure shows the core 102, the outer layer 112 surrounding the core 102, and the outer coating 114. In FIG. 8, the outer layer 112 is a braided layer.

[0061] Figure 10 shows an example of a single - direction control shaft. A pull - wire is used to pull the tip of the shaft into a predetermined curve. A specific shape can be selected by operation.

[0062] Figure 11 is a schematic perspective view of another configuration of the shaft according to the present invention. This figure shows an example of a bi - directional shaft. By using two pull - wires, the tip of the shaft can be pulled in two opposite directions. This configuration is particularly useful for the controlled movement and placement of the distal tip since it can be maneuvered in multiple planes.

[0063] Figure 12 is a schematic cross - sectional depiction of another configuration of the shaft according to the present invention. In Figure 12, the shaft has four thin - thickness sections located at polar - angle positions 90° apart from each other. Pull - wires 156, 157, 159, 161 are respectively arranged in each of the thin - thickness sections 148, 150, 152, 154. With this configuration, the shaft can be pulled in four different directions. The shaft has two planes of high flexibility, one cutting through thin - thickness sections 148 and 152 perpendicular to the plane of cross - section C. The second plane of high flexibility cuts through sections 150, 154 perpendicular to the plane of cross - section C.

[0064] Figure 13 is a schematic cross - sectional depiction of another configuration of the shaft according to the present invention. This figure shows a shaft having four thin - thickness sections 148, 150, 152, 154 located at polar - angle positions 90° apart from each other. Two pull - wires 160, 163 are respectively arranged in thin - thickness sections 148 and 150 at polar - angle positions 90° apart from each other.

[0065] Figure 14 is a schematic cross-sectional view of another configuration of the shaft according to the present invention. It shows a shaft having four thin-thickness sections 148, 150, 152, 154 located at pole angle positions 90° apart from each other. Two pull wires 162, 169 are respectively arranged in the thin-thickness sections 150 and 154 located at pole angle positions 180° apart from each other. Two reinforcing wires 164, 165 are respectively arranged in the thin-thickness sections 148, 152 located at pole angle positions 180° apart from each other. This configuration has a plane with high flexibility that coincides with a plane that cuts the thin-thickness sections 150 and 154 perpendicular to the plane of cross-section C. The plane with high rigidity coincides with a plane that cuts the thin-thickness sections 148 and 152 perpendicular to the plane of cross-section C.

[0066] Figure 15 is a schematic cross-sectional view of another configuration of the shaft according to the present invention. The figure shows a shaft having four thin-thickness sections 148, 150, 152, 154 located at pole angle positions 90° apart from each other. Two reinforcing wires 167, 168 are arranged in one of the thin-thickness sections 152. The pull wire 166 is arranged in the thin-thickness section 150. The pull wire 170 is arranged in the thin-thickness section 154.

[0067] Figure 16 is a schematic cross-sectional view of a shaft 200 in the state of the prior art. The figure shows a core 201 including an inner radius 202 and an outer radius 204. Two lumens 206, 207 are extruded into the core between the inner radius 202 and the outer radius 204 of the core. Reinforcing bars 208, 210 are respectively arranged in each lumen 206, 207. Between the inner radius 202 and the outer radius 204 of the core, a third lumen 212 is within the core. A pull wire 214 is arranged in the lumen 212.

[0068] The advantage of this shaft can be seen in the fact that the mechanical properties of the shaft are improved due to the improved geometry and arrangement without any additional cost.

Description of the reference numerals

[0069] 100 Shaft 102 Tubular Core 104 Inner Periphery 106 Outer Periphery 108 Thin-Thickness Section 110 Thin-Thickness Section 112 Outer Layer 114 Outer Coating 116 High-Flexibility Plane 118 High-Rigidity Plane 120 Thin-Thickness Section 122 Thin-Thickness Section 124 Thin-Thickness Section 126 Thin-Thickness Section 128 Reinforcing Wire 129 Reinforcing Wire 130 Reinforcing Wire 131 Reinforcing Wire 132 High-Flexibility Plane 134 High-Rigidity Plane 136 High-Flexibility Plane 138 High-Rigidity Plane 140 Thin-Thickness Section 142 Thin-Thickness Section 144 Pull Wire 146 Pull Wire 148 Thin-Thickness Section 150 Thin-Thickness Section 152 Thin-Thickness Section 154 Thin-Thickness Section 156 Pull Wire 157 Pull Wire 159 Pull Wire 160 Pull Wire 161 Pull Wire 162 Pull Wire 163 Pull Wire 164 Reinforcing Wire 165 Reinforcing Wire 166 Pull Wire 167 Reinforcing Wire 168 Reinforcing Wire 169 Pull Wire 170 Pull wire 200 Prior art shaft 201 Prior art core 202 Prior art inner radius 204 Prior art outer radius 206 Prior art lumen 207 Prior art lumen 208 Prior art reinforcing bar 210 Prior art reinforcing bar 212 Prior art lumen 214 Prior art pull wire

Claims

1. A shaft (100) for a catheter having a cross-section (C) with a longitudinal axis (L) defining a radial distance and a polar axis (ρ) defining an angular position (φ), a tubular core (102) having an inner circumference (104) and an outer circumference (106), an outer layer (112) for improving mechanical properties, the outer layer (112) surrounding the tubular core (102) such that the outer circumference (106) of the tubular core (102) faces the outer layer (112), comprising: the outer circumference (106) has a concave meniscus shape such that the radial distance between the outer circumference (106) and the inner circumference (104) varies at different polar angular positions (φ), forming sections of different stiffness at different angular positions (φ) in the single lumen tubular core (102), the shaft (100), wherein different planes of the shaft that are oriented along the longitudinal axis (L) and cut the cross-section (C) at different polar angular positions (φ) have different bending properties determined by the stiffness of the sections.

2. The shaft (100) according to claim 1, wherein the sections of different stiffness consist of thin sections (108, 110, 120, 122, 124, 126, 140, 142, 148, 150, 152, 154), and the thin sections are formed by grooves (108, 110, 120, 122, 124, 126, 140, 142, 148, 150, 152, 154) on the outer circumference (106) of the tubular core (102) extending along the longitudinal axis (L).

3. The shaft (100) according to claim 2, wherein at least two thin sections (108, 110, 120, 122, 124, 126, 140, 142, 148, 150, 152, 154) are arranged at polar angular positions (φ) that are 180° apart from each other.

4. The shaft (100) according to any one of claims 1 to 3, wherein the outer layer (112) comprises a braided layer, a wound layer, or another reinforcing layer.

5. The shaft (100) according to any one of claims 1 to 4, wherein at least one reinforcing wire (128, 129, 130, 131, 164, 165, 167, 168) is arranged in one or more thin sections (108, 110, 120, 122, 124, 126, 140, 142, 148, 150, 152, 154).

6. At least one pull wire (144, 146, 156, 157, 159, 161, 160, 163, 162, 169, 166, 170) is arranged in one or more sections (108, 110, 120, 122, 124, 126, 140, 142, 148, 150, 152, 154) of thin thickness for steering, the shaft (100) according to claims 1 to 5.

7. The shaft (100) according to claims 1 to 6, further comprising an outer coating (114) surrounding the outer layer (112).

8. The shaft (100) according to claim 7, which cites claim 2, wherein the outer coating (114) comprises a polymer material that at least partially penetrates the outer layer (112) and the sections (108, 110, 120, 122, 124, 126, 140, 142, 148, 150, 152, 154) of thin thickness.

9. Forming a tubular core (102) having a cross-section (C) including an inner circumference (104) and an outer circumference (106); Forming sections of different stiffness at different angular positions (φ) in the tubular core (102) having a single lumen, and forming a concave meniscus shape on the outer circumference (106) such that the radial distance between the outer circumference (106) and the inner circumference (104) is different at different polar angular positions (φ); Forming an outer layer (112) for improving mechanical properties, the outer layer (112) surrounding the tubular core (102) such that the outer circumference (106) of the core (102) faces the outer layer (112); A method of manufacturing a shaft for a catheter, comprising.

10. The method according to claim 9, wherein the sections of different stiffness include forming sections (108, 110, 120, 122, 124, 126, 140, 142, 148, 150, 152, 154) of thin thickness, and the sections of thin thickness are formed by grooves (108, 110, 120, 122, 124, 126, 140, 142, 148, 150, 152, 154) on the outer circumference (106) of the tubular core (102) extending along the longitudinal axis (L) of the tubular core (102).

11. The method according to claim 10, further comprising the step of incorporating at least one reinforcing wire (128, 129, 130, 131, 164, 165, 167, 168) and / or at least one pull wire (144, 146, 156, 157, 159, 161, 160, 163, 162, 169, 166, 170) into the thin-thickness sections (108, 110, 120, 122, 124, 126, 140, 142, 148, 150, 152, 154).

12. The method according to claim 11, wherein the step of incorporating at least one reinforcing wire (128, 129, 130, 131, 164, 165, 167, 168) and / or at least one pull wire (144, 146, 156, 157, 159, 161, 160, 163, 162, 169, 166, 170) into the thin-thickness sections (108, 110, 120, 122, 124, 126, 140, 142, 148, 150, 152, 154) is performed before or during the formation of the outer layer (112).

13. The method according to any one of claims 9 to 12, further comprising the step of applying an outer coating (114).

14. The method according to claim 13, which depends on claim 10, wherein the outer coating (114) is made of a polymeric material, and the polymeric material is formed by a reflow or coating process that at least partially penetrates the outer layer (112) and the thin-thickness sections (108, 110, 120, 122, 124, 126, 140, 142, 148, 150, 152, 154).

15. A catheter comprising a shaft according to any one of claims 1 to 8.

Images