Flexible catheter shaft frame with seams

Abstract

To provide an improved catheter support frame and a manufacturing method.SOLUTION: The designs herein can be for a flexible and kink-resistant catheter with a support tube which can be radially expanded to enable it to be slid over an inner liner on a mandrel during assembly. The designs are flexible enough for access to remote vessel occlusions but also benefit from good compressive and tensile stiffness. The designs can have a laser cut frame with an interlocking structure of circumferentially discontinuous rib struts. The discontinuities can be aligned to form at least one continuous axial seam which is separable to allow the radial expansion during manufacturing. The struts of the frame can be coated with or encapsulated in a series of polymeric outer jackets to give variable stiffness and to prevent disengagement of the interlocking structure while the catheter is pushed through a tortuous anatomy.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure generally relates to devices and methods for accessing blood vessels during endovascular medical procedures. More specifically, the present disclosure relates to catheters that can expand radially to facilitate the manufacture and assembly of catheters.

Background Art

[0002] Catheters perform a wide range of functions in endovascular medical procedures. A catheter is typically a thin tube made of a medical grade material that can be inserted into the body, deliver drugs or other devices, perform surgeries, be used to remove obstructions from blood vessels, and be used for a variety of other purposes.

[0003] There are many challenges related to access that can make it difficult to access the target site. Remote areas such as the neurovascular bed are difficult with conventional techniques because the target blood vessels are small in diameter, are far from the insertion site, and are very tortuous. Suction and / or access catheters for removing blood vessel obstructions in such sites are required to be able to withstand high bending stresses without kinking and access the target site without traumatizing loops and gradually decreasing blood vessel sizes. It is not uncommon for a catheter to have to pass through a tortuous path with multiple loops, and segments of blood vessels can have several extreme bends in succession during a movement of just a few centimeters.

[0004] Catheters must also possess excellent compressive stiffness (for ease of insertion and stability and integrity when thrombus retrieval devices are drawn in) and excellent tensile stiffness (to avoid stretching and deformation when under tension, such as when retrieving a large thrombus into the outer sheath). Managing the transition of stiffness from the proximal to distal portion to avoid kinking is crucial for these devices. Catheters must also allow for easy delivery of other devices through the lumen. For these reasons, conformability, flexibility, kink resistance, and internal lubricity are often important design parameters associated with catheters used in these procedures. However, for designers of conventional catheters, effectively combining these properties without significant trade-offs can be challenging.

[0005] The stiffness of different parts of a catheter can be adjusted to suit specific applications by changing the materials or modifying the manufacturing method of the catheter. Many current catheters control the transition from harder to softer materials by changing the structure of the braided material's framework (changing the braided PIC count or coil pitch), utilizing a custom-made, machined metal support frame framework, and / or changing the durometer hardness of the surrounding polymer material. The coils of braided wire used to reinforce the catheter shaft are often continuous, very fine-sized superelastic metal or stainless steel, which are prone to kinking and can be difficult to manufacture with the consistency required for uniform products. These materials also bring significant costs and complexity.

[0006] Auxiliary devices (such as guidewires, microcatheters, and thrombectomy / stent retriever devices) must be delivered easily through the lumen without excessive friction caused by coupling. Many recent devices attempt to significantly improve the lubrication of the catheter lumen by utilizing an internal low-friction liner. Such devices can be complex to manufacture because the inner diameter of the braided or metal support frame skeleton must be approximately the same as, or slightly smaller than, the outer diameter of the inner liner on the mandrel during construction. Current skeleton designs do not allow for the radial expansion necessary to slide over the liner without excessive friction during assembly. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The design of the present invention aims to provide an improved catheter support frame and manufacturing method to address the aforementioned defects. [Means for solving the problem]

[0008] The technological innovations of this disclosure include controlling axial and lateral stiffness along the length of the catheter shaft and making the support tube beneath the shaft radially expandable for assembly onto a liner on a mandrel during manufacturing. The catheter shaft tube can be cut, for example, from a hypo tube into a series of circumferentially discontinuous ribs in the axial direction. The ribs can form an interlocking structure to give the shaft good resistance to both tensile elongation and compressive shortening while maintaining excellent lateral flexibility. By aligning the circumferential discontinuities of the ribs, a longitudinal seam can be formed, thereby expanding the frame of the shaft to facilitate assembly with a low-friction inner liner. In this design, the stiffness transition along the length of the shaft can be controlled to avoid kinking by changing the mechanism into which the support tube is cut across different axial segments of the shaft.

[0009] A catheter may have a shaft comprising a support tube, a proximal end, and a distal end. The support tube may have an inner liner arranged around the longitudinal axis. The support tube may have a series of axial interlock segments formed from a plurality of circumferentially discontinuous rib struts. This structure can create a substantially tubular profile along the longitudinal axis and define a lumen extending inward through the inner liner. In some examples, a spine may connect each of the plurality of ribs, and the spine follows a nonlinear profile around and along the axis of the support tube due to the circumferential discontinuities of the ribs.

[0010] The circumferentially discontinuous ribs of the support tube, due to the relative longitudinal alignment of the axial divisions within the ribs of the interlock segments, can form one or more axial seams in the support tube. In this way, the support tube can open radially along seams similar to those of a clamshell. Before assembly, the support tube may have a nominal non-expanding inner diameter equal to or slightly smaller than the outer diameter of the inner liner. When expanded, the support tube may have an expanded inner diameter slightly larger than the outer diameter of the inner liner.

[0011] The stiffness of the catheter in different axial portions of the support tube can also be adjusted by changing the spacing between adjacent interlock segments. In one example, the first segment pitch measured between adjacent interlock segments of a first pair may be the same as the second segment pitch measured between adjacent interlock segments of a second pair. In another example, the first segment pitch measured between adjacent interlock segments of a first pair may be different from the second segment pitch measured between adjacent interlock segments of a second pair.

[0012] The way in which interlock segments interlock with each other around an axial seam(s) can take several forms. In one example, each of an axial series of interlock segments may have a top half that may have a pair of inset teeth extending from its respective rib support. On the opposite side, the interlock segments may have a bottom half that has a pair of outset teeth extending from its respective rib support that can define and boundary the receptive space between them. In some cases, the inset and outset teeth of the interlock segments may have triangular, quadrilateral, or other polygonal shapes. In other examples, the teeth may form substantially L-shaped projections.

[0013] The juxtaposition of the receiving space of the bottom half and the inset teeth of the top half allows the halves to be configured to engage complementaryly with each other. When the support tube is assembled, this engagement creates an aligned gap of one or more axial seams. The gap may be defined around the interface between the receiving space of the bottom half and the inset teeth of the top half, such that the seam(s) are continuous below the long axis of the support tube. If the seams follow this perimeter around the tooth projections along the axis, they can have circumferential and axially nonlinear profiles. The spines may also follow alternating nonlinear paths between the top and bottom halves along the rib.

[0014] The distal end of the support tube may be configured to have one of several different tip or mouths attached depending on the purpose of a given procedure. In one case, the distal end may feature a plane substantially perpendicular to the longitudinal axis. The plane may be the most distal rib or, more specifically, a ringed bracket. Such a plane may allow for the attachment of a therapeutic tip, an expandable mouth, or other similar devices.

[0015] In other cases, the flexible support tube for the catheter shaft body may have a laser-cut framework of struts that form substantially circular ribs distributed along the longitudinal axis of the support tube. The ribs may have one or more circumferential discontinuities around the support tube. To connect the individual ribs, a spine may extend the length of the long axis of the support tube and navigate around the tube and the gaps formed by the discontinuities of the ribs. The distal end of the support tube may have a surface configured to connect the catheter tip or opening for endovascular procedures.

[0016] The circumferential discontinuities in the ribs can create gaps that can be aligned, forming one or more axial seams. The continuity of one or more seams can give the support tube some degree of radial expansion capability. This expansion allows the support tube to be sized to a nominal inner diameter smaller than the outer diameter of the inner low-friction liner. Then, when the catheter is assembled during manufacturing, the support tube can expand to slide along the liner on the mandrel.

[0017] The ribs of the support framework can be grouped to form a series of axial interlock segments having a substantially tubular profile along the longitudinal axis. Each interlock segment may have a top half and a bottom half. In some examples, the half can be divided by a plane passing through the longitudinal axis and at least a portion of one or more seams parallel to the axis. In some examples, a pair of inset teeth may extend from each rib support of the interlock segment on the top half. Similarly, the corresponding bottom half of the same interlock segment may have a pair of outset teeth extending from each rib support and bounding the receiving space.

[0018] The interlock segments can be aligned so that, when the support tube is assembled, each pair of inset teeth in the top half and each pair of outset teeth in the bottom half are juxtaposed with each other and separated circumferentially by one or more axial seams. As a result, the teeth can interlock with each other like a zipper but cannot be fixedly connected to each other. The inset teeth in the top half can reside within the receptive space created by the outset teeth in the bottom half. Thus, the axial expansion of the support tube can also be limited, provided that the teeth are shaped in such a way that they physically prevent expansion, by overlapping and engaging the inset teeth within the receptive space of the outset teeth.

[0019] The inset teeth of each apical half and the outset teeth of each basal half of the interlock segment may have projections perpendicular to the longitudinal axis of the support tube. In other examples, the teeth may have projections parallel to the longitudinal axis, or projections that are both parallel and perpendicular to the axis. These shapes, combined with the overlap of the teeth in the receptive space, may mean that one or more axial seams are continuous gaps defined at the outer periphery of the interface between the outset teeth of the basal half of the interlock segment and the inset teeth of the apical half. This periphery can give one or more axial seams nonlinear profiles in the circumferential and axial directions. The seams restrict the total expansion due to tooth engagement while allowing the support tube to expand radially. Tooth engagement can also restrict the expansion of the support tube in any axial direction.

[0020] The dimensions of the support tube structure can also be modified to change the stiffness profile of different parts of the catheter. For example, the width of the first rib in one rib support may be the same as or different from the width of the second rib in another rib support. Similarly, the first segment pitch measured between adjacent interlock segments of a first pair may be the same as or different from the second segment pitch measured between adjacent interlock segments of a second pair.

[0021] The rigidity and flexibility of the catheter tube can also be adjusted using other processes beyond dimensional configurations. For example, a series of polymer jackets can be reflowed onto a support tube to bond the underlying structure and create the outer surface of the catheter body. These outer jackets can increase columnar rigidity in the proximal portion and lateral flexibility in the distal portion by varying their durometer hardness.

[0022] The invention may also include a method for manufacturing a catheter. This method may include the step of positioning a low-friction inner liner on a first application mandrel. The liner may be PTFE or a similar polymer.

[0023] Another step may include forming a support tube having an axial seam that allows for radial expansion of the support tube. In some examples, the support tube can be machined from a hypo tube of a shape memory superelastic alloy such as nitinol (NiTi) so as to have a non-expanding inner diameter equal to or slightly smaller than the outer diameter of the inner liner on the applied mandrel.

[0024] The support tube can be laser-cut to have multiple circumferentially discontinuous ribs arranged along the longitudinal axis between the proximal and distal ends. A seam can be formed through the alignment of the circumferential discontinuities of the ribs along the axis. Thus, the ribs can also be arranged alternately between the top and bottom halves, forming a spine along the circumferential and axial nonlinear profiles connecting each rib.

[0025] The axial seam can be extended by extending the support tube on a second oversized mandrel that is substantially tubular. The oversized mandrel may have an outer diameter slightly larger than the outer diameter of the inner liner of the mandrel of application. This method then allows the laser-cut support tube on the oversized mandrel to be given at least an austenitic finish (A) of the alloy. f ) Below a certain temperature, ideally a martensite finish (M f)It can have a step of cooling to a temperature below. Alternatively, the support tube can also be cooled to a desired temperature before expanding on the extra-large mandrel. Then, the second extra-large mandrel can be removed, and the radially expanded support tube is positioned around the inner liner on the first application mandrel.

[0026] The plurality of outer polymer jackets can be reflowed or laminated onto the support tube. The jackets can be arranged axially in series and have different durometer hardnesses. In an alternative, the jackets can be applied radially in series or can be a blend of materials. The reflow process can bond the liner and the support tube by flowing through the gaps between the ribs. Then, once the structure is joined, the first application mandrel can be removed.

[0027] Other aspects and features of the present disclosure will become apparent to those skilled in the art by considering the following detailed description in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0028] The above and further aspects of the present invention will be further considered by referring to the following description in conjunction with the accompanying drawings. The drawings are not necessarily to scale and instead are focused on illustrating the principles of the present invention. The figures depict one or more implementations of the device of the present invention by way of illustration and not limitation. [Figure 1] It is a view of an expandable catheter support tube on a mandrel according to an aspect of the present invention. [Figure 2] It is a representation of the flat pattern of FIG. 1 showing the top half and bottom half of an interlock segment according to an aspect of the present invention. [Figure 3] It shows another exemplary flat pattern of a support tube according to an aspect of the present invention. [Figure 4] It is a view of an alternative expandable catheter support tube according to an aspect of the present invention. [Figure 5] It shows a flexible catheter support tube having an outer polymer layer applied according to an aspect of the present invention. [Figure 6] Figure 5 shows a cross-sectional view illustrating an exemplary outer polymer layer configuration according to an aspect of the present invention. [Figure 7] This is a diagram showing an alternative outer polymer layer configuration according to an aspect of the present invention. [Figure 8] This is a diagram of an expandable catheter support tube having an attached expandable distal tip according to an aspect of the present invention. [Figure 9] Another example of an expandable catheter support tube having an attached expandable distal end according to an aspect of the present invention is shown. [Figure 10A] This figure shows a possible method for manufacturing an expandable catheter support tube according to an aspect of the present invention. [Figure 10B] This figure shows a possible method for manufacturing an expandable catheter support tube according to an aspect of the present invention. [Figure 10C] This figure shows a possible method for manufacturing an expandable catheter support tube according to an aspect of the present invention. [Figure 10D] This figure shows a possible method for manufacturing an expandable catheter support tube according to an aspect of the present invention. [Figure 10E] This figure shows a possible method for manufacturing an expandable catheter support tube according to an aspect of the present invention. [Figure 11] Figures 10A to 10E show process flowcharts of the manufacturing method according to an embodiment of the present invention. [Modes for carrying out the invention]

[0029] The objective of the design presented herein may be an elongated catheter for vascular applications, possessing variable flexibility and kink resistance. The design is flexible enough to access distant vascular occlusions, while also benefiting from good compressive and tensile stiffness. The design may have a proximal and distal end, as well as a laser-cut support tube frame extending between them. The support tube frame may have an interlocking structure of rib supports with at least one continuous split seam to allow some radial expansion during the manufacturing process while maintaining longitudinal stiffness. A low-friction inner liner may be placed on the inner surface of the frame. An outer polymer layer or laminated jacket may coat or encapsulate the frame supports and prevent disengagement of the interlocking structure while the catheter is pushed through a winding anatomical structure. The distal end may allow connection of one of several catheter tip sections, such as an expandable funnel opening for aspiration and thrombus retrieval.

[0030] The catheter may also be compatible with relatively low-profile access sheaths and external catheters, thus allowing for easy and reliable closure of the puncture wound in the patient's groin (in the case of thigh access). Although this description is often made in the context of mechanical thrombectomy or other treatments in the neurovascular bed, the devices and methods described can be readily adapted to other procedures and other body passages.

[0031] Herein, specific embodiments of the present invention will be described in detail with reference to the drawings, where the same reference numerals indicate functionally similar or identical elements. Accessing various vessels within the vascular system, whether coronary, pulmonary, or cerebral, involves well-known procedural steps and the use of many conventional commercially available accessory products. These products include angiographic materials, rotary hemostatic valves, luer connectors, guidewires, etc., which are widely used in laboratory and medical procedures. Although they may not be specifically mentioned by name, when these or similar products are used with the devices and methods of the present invention in the following description, their functions and exact configurations will not necessarily be described in detail.

[0032] Returning to the diagram, Figure 1 shows a diagram of a catheter shaft support tube frame 100 for use in endovascular procedures within a patient's blood vessels. The support tube is shown positioned around a low-friction inner liner 160 on a mandrel 10. The support tube 100 can generally be a tubular framework of struts between a proximal end 112 and a distal end 114, having a lumen 119. Multiple rib struts 118 can form an axial series extending around a longitudinal axis 111. The struts can be laser-cut from, for example, a hypo tube. In another embodiment, the support tube can be an injection-molded polymer support structure. Mechanisms that bias bending or promote twisting around a specific plane can also be incorporated into the strut framework to reduce the strain applied. This allows the catheter to maintain excellent lateral flexibility without a tendency to expand under tension or kink under compression.

[0033] The rib supports 118 can be discontinuous in the circumferential direction, thereby allowing the longitudinal seam 116 to divide the structure of the support tube 100 and enable some degree of radial expansion. Radial expansion is beneficial, for example, if, during manufacturing, the laser-cut support tube structure can be expanded to fit onto the inner liner 160 or other layers on the support mandrel 10, as shown herein. If it cannot be expanded on the liner, the friction will be too great, preventing the frame from effectively sliding on the liner / mandrel pair during assembly. Furthermore, if the support tube is larger in size than the diameter of the liner from the outside, it cannot sit concentrically on the liner, resulting in a catheter with excessively thick walls.

[0034] Next, the support tube 100 may have an expanded inner diameter 108 that is larger than the outer diameter 162 of the liner 160 on the mandrel. In this unrestrained state, the expanded ID 108 may be only slightly larger than the OD (0.001 inches, or at most 0.002-0.003 inches) in the case of the liner.

[0035] The seam 116 may be continuous along the entire length of the support tube 100, while the spine 126 may be present by continuously extending rib supports 118 circumferentially on the radially opposite side of the seam. The spine 126 connects the structure longitudinally, but can allow for greater flexibility than, for example, if a continuous linear spine member were present along the length of the support tube 100 parallel to the longitudinal axis 111.

[0036] In some examples, the support tube 100 can be integrally formed with an expandable tip 310 that can expand to a larger radial size when deployed from the distal end of the sheath or outer catheter. The expanded tip can provide improved suction efficiency and, once removed from the container and taken up, can also allow for gradual compression of the captured thrombus.

[0037] Figure 2 shows an example of a flat cutting pattern of the support tube 100 in Figure 1. The pattern of the rib support 118 can form a series of interlock segments 120, 130, and 140. The interlock segments can be axially symmetrical with respect to each other, as shown in the figure, or the pattern can be irregular and the segments can be cut asymmetrically. The longitudinal axis 111 can divide the pattern of interlock segments 120, 130, and 140 into a top half 102 and a bottom half 104. The two halves can have a mechanism configured to interlock with the other half when the tube is assembled, forming a seam 116 while resisting axial expansion and improving the backup support of the catheter. The axial stiffness is supported by the spine 126 connecting the ribs 118 and can follow an alternating nonlinear path between the top half 102 and the bottom half 104 of the support tube 100.

[0038] For example, the top half 102 of the interlock segment may have a pair of inset teeth 103 cut in a shape that is mainly square, as shown in the figure. Similarly, the bottom half 104 of the segment may have a pair of outset teeth 105. The outset teeth may border the receptive space 106 of each interlock segment into which the inset teeth 103 can engage. In other examples, the teeth may have triangular, quadrilateral, or other polygonal shapes, which can interlock and also improve the torque response of the catheter.

[0039] It can be understood that the receiving space 106 for connecting the inset teeth 103 of the top half 102 and the outset teeth 105 of the bottom half 104 can be of different sizes for different interlock segments 120, 130, and 140, so that the size of the gap created by the inset teeth and the receiving space can vary according to the design parameters of different parts of the support tube 100. Thus, when fixed together, the interlock segments can affect the flexibility and / or biased bending of the assembly along a particular plane.

[0040] The bending stiffness of the support tube 100 can also be adjusted by a combination of varying the cutting width and the rib width. If the cutting width is kept constant (e.g., the width of the laser beam), the bending stiffness can be adjusted by changing the rib width. If the cutting width is varied, the rib width may be kept constant or varied, and the material can be removed using a laser. It is understood that by using a cutting width equal to the cutting width of the laser beam, no material fragments are removed, and manufacturing costs are significantly reduced. On the other hand, by removing material fragments using a laser, a greater variation in shaft design can be obtained. It will also be understood that by combining both approaches, a cost-effective cutting / processing can be performed at the proximal end of the shaft, and a more cost-effective approach can be taken at the distal end, as more complex cutting is required to achieve the desired flexibility. For example, the proximal portion of the shaft can be cut from SS and joined to the distal portion cut from a superelastic alloy such as NiTi. This structure can bring the advantages of NiTi to the distal end of the device while reducing overall costs, which is necessary for increased elasticity in narrow bending curves and also for providing some degree of expansion and recovery properties. In such devices, the SS and NiTi sections can be joined by direct welding or by welding to a more weldable intermediate metal, such as a platinum marker band. Alternatively, a laser-cut interlocking mechanism can hold both cut tube sections together longitudinally. The tubes can also be held together radially by an outer membrane cover or jacket.

[0041] In some cases, the small size of the axial and radial gaps between the teeth of the interlock segment can provide resistance to stretching and / or compression of the support tube while maintaining the lateral flexibility necessary for navigation through the vascular system. This can prevent the support tube from stretching when it is withdrawn into the external catheter, and it can also maintain stability to prevent it from bundling when a stent river or another device is withdrawn from the lumen.

[0042] Figure 3 shows an example of an alternative flat pattern. The illustrated pattern has inset teeth 103 and outset teeth 105 which are substantially L-shaped projections 121 or variations thereof, and the interlock teeth can be oriented in both the circumferential and longitudinal directions. The discontinuity of the seam significantly improves the degree of freedom of catheter bending compared to when the ribs are connected using continuous, rigid spine members. Compared to the pattern shown in Figure 2, this tooth orientation can help prevent the teeth 103, 105 from hinged when the catheter is navigated through narrow bends in the body passage, at the cost of limiting some of the radial expansion capability of the support tube 100. After lamination of the outer jacket (not shown), this structure can provide a high effective modulus and good integrity in both tension and compression when recovered against resistance.

[0043] The catheter shaft can also be adjusted for desired flexibility performance by adjusting various dimensional parameters of the laser-cut frame of the support tube 100, as shown in Figure 4. The pitch between interlock segments can be designed so that the structure of the support tube 100 is more rigid and denser in the more proximal area and more flexible in the distal area. One way to measure the pitch of the interlock segments may be the longitudinal distance measured between the most distal rib 124 of one interlock segment 130 and the most distal rib 134 of the adjacent interlock segment 140. Thus, the pitch can be changed to alter the intermediate length of the dividing seam 116 of a given interlock segment without affecting the interlock capability.

[0044] For example, the first segment pitch 122 of the interlock segment 130 can be narrowed or shortened near the proximal end 112 of the support tube to provide better followability and torque response. Similarly, near the distal end 114, where lateral flexibility is a greater concern, the support tube 100 can transition to a second segment pitch 132 of the interlock segment 140, which is larger than the first segment pitch 122, to better optimize their physical capabilities. The change in pitch also changes the spacing between the interlocking tooth extensions 117 within the adjacent receiving space 106.

[0045] The segment pitches 122 and 132 can, alternatively, be continuously varied along the longitudinal length of the support tube 100. As a result, adjacent interlock segments 120, 130, and 140 of the tube, together with each consecutive segment, can gradually move closer to or further apart from each other at a small but progressively constant rate. The continuously varying pitch provides a smoother stiffness transition along the length of the support tube 100, while preventing the formation of kink points that might otherwise form in transitions with higher stiffness gradients. This configuration also helps to provide a balanced and consistent pressing or thrusting force along the longitudinal direction of the support tube 100, ensuring that the operator receives appropriate tactile feedback when manipulating the catheter during the procedure.

[0046] Another design variable that can be changed to optimize the rigidity and flexibility of the support tube 100 is the width or cross-sectional shape of the struts forming the ribs 118. For example, reducing the cross-section of the ribs increases the space between the ribs, making it easier to bend the support tube. As shown in Figure 4, the rib width 141 of the struts of the more proximal interlock segment 120 can be greater than the second, more distal rib width 142 of another interlock segment 140.

[0047] The cut support tube 100 may have an outer polymer layer 180 or jacket around the ribs 118 of the interlock segment, as shown in Figure 5. The outer polymer layer 180 or jacket can be made of various medical-grade polymers such as PTFE, polyether block amide (Pebax®), or nylon. For example, to add column strength and pushability to the catheter, the material can be selected such that the more proximal segments are generally harder and less flexible as they approach the proximal end 112 (by durometer hardness, flexural modulus, etc.). Similarly, segments of more flexible material can be used distally.

[0048] In one example, the outer jacket 180 can be reflowed into the space between the ribs 118 on a laser-cut hypotubule. After such a process, sometimes there may be radially protruding material at the location of the laser-cut rib supports 118. In this situation, all excess material above the supports can be removed by pulling the shaft through a sizing die, thereby making the overall outer diameter of the support tube 100 shaft consistent with the desired delivery profile. Alternatively, a non-uniform or ribbed profile may be desired to reduce friction between the outer surface of the catheter and the outer sheath or blood vessel.

[0049] In another example, the outer polymer layer 180 can be injection molded into the space of the support tube 100 during manufacturing. In yet another example, the layer or jacket 180 can be bonded to the support column 118 of the support tube 100 using an adhesive having a primer component for bonding.

[0050] Figure 6 shows a cross-sectional view of the catheter body wall shown in Figure 5. The inner liner 160, such as PTFE, can offer the advantage of reducing friction with auxiliary devices advancing through the catheter lumen 119. As described above, the outer polymer layer or jacket 180 can be bonded to the laser-cut support tube structure by reflow, injection molding, or other methods.

[0051] The use of internal and external polymer coatings that can extend, interface with, or blend with each other through the space within the laser-cut support tube 100 helps enable the teeth of the interlock segments to bend and interlock without plastic deformation. Thus, the ribs 118 can have a degree of independent bending capability, while being subject to limited constraints imposed by the outer jacket(s).

[0052] The layout and structure of the inner liner 160 and the outer jacket 180 can be modified. For example, the material of the outer jacket 180 can extend radially inward to or beyond the inner surface of the support tube 100, or to an intermediate position between the inner and outer diameters of the support tube between the rib supports 118. Alternatively, the outer jacket 180 can be bonded only to the outer surface of the support tube. Having a jacket 180 bonded only to the outer diameter allows the catheter to be made more rigid by a jacket that extends more radially inward relative to the thickness of the support tube wall, thus allowing the rib supports 118 of the support tube to bend more freely. The unfilled gaps between the ribs 118 of the support tube allow the ribs to move freely in the axial direction. Other variations in rigidity can be achieved by having an outer jacket 180 composed of a composite of a series of radial jackets 182, each having a different thickness and / or being made of different materials. It can also be understood that the series of radial jackets 182 may be arranged in different ways for different axial segments of the catheter.

[0053] As mentioned above, the outer polymer layer can also be formed from a series of polymer jackets in the axial direction. Different jackets or sets of jackets 183, 184, and 185 may be arranged around the rib 118 at different lengths along the axis of the support tube 100 to give different portions of the tubular portion of the catheter distinct indentation and flexibility properties, as shown in Figure 7. The orientation shown is illustrative and not limiting. Figure 7 shows portions of the support tube 100 having three polymer outer jacket layers 183, 184, and 185, respectively. Factors such as wall thickness and the length of individual layers can be varied to satisfy the rigidity or flexibility of the portion of the support tube 100. Dimensions must also be selected so that the catheter meets the critical bending criteria determined according to the application.

[0054] In many cases, the materials can be selected such that the jacket layers 183, 184, and 185 decrease distally on the durometer. By constructing the jackets axially continuous and using polymers with different durometer hardnesses, the overall stiffness of the catheter can be transitioned from a stiff, easily compressible state at the proximal end to an extremely flexible state at the distal end. Common choices for the outer jacket layers may be PTFE and Pebax®, but much more specialized materials or blends can be incorporated into specific axial portions of the support tube 100. In the more proximal portions of the catheter where axial stiffness and resistance to collapse are important, the jacket segments can be made from suitable and robust polymers such as polyimide, nylon, polypropylene, or other materials with higher density. For more distal portions where flexibility is required, the jacket segments may be, for example, polyurethane, PVC, low-density polyethylene (LDPE), or other polymers with suitable modulus and flexibility. Blends, co-extrusions, and / or mixtures of these materials and other materials can also be used to obtain the correct material properties for specific segments.

[0055] The transitions between jackets can be tapered or slotted to provide a gentler rigidity transition between adjacent jackets that run continuously in the longitudinal direction. When applied in a reflow or lamination process, the jackets can bond the underlying structure to each other and provide a smooth-looking finish. Slots or other mechanisms can then be added using machining or forming dies.

[0056] At the distal end 114 of the support tube 100, following the most distal interlock segment, the laser-cut structure may have a surface 115 substantially perpendicular to the longitudinal axis 111. The surface may be another circular rib, collar, or other suitable anchor structure. Such a surface may allow for the attachment of a therapeutic tip, an expandable opening, or other similar device.

[0057] Figure 8 shows an example where the flat surface 115 ultimately appears as an independent circular rib. The rib of the flat surface may have a single connection point to the furthest interlock segment. In another modification, multiple connection points may be located at various clock positions around the axis.

[0058] The exemplary expandable tip 310 shown in Figure 8 is a column framework which may have four distal hoops 315 connected to four support arms 316. Each support arm may have a single attachment point to the distal surface 115 at the distal end 114 of the support tube 100, or they may share a connection. In one example, a pair of hoops 315 may be tapered to a single support arm 316 such that there are two connection points 180 degrees apart. The tip 310 can then move and bend on a hinge along the plane created by these connection points.

[0059] The tip 310 is made of a shape-memory material and can be thermoset so that it self-expands when deployed from the distal end of the outer sheath or catheter. The support arm 316 may have an enlarged cell opening 317, which allows the arm to shorten or lengthen on opposite sides around the longitudinal axis 111 of the tip frame, allowing the device to easily follow winding vascular pathways via the outer sheath or catheter. The branching of the support arm 316 can also allow the arm to bend and torque more freely than if a single support without the cell 317 directly connected the distal hoop 315 and the distal surface 115.

[0060] In many cases, the funnel shape formed by the tip 310 can be covered with another non-traumatic polymer jacket or membrane (not shown). The enlarged opening of the tip can improve suction efficiency, stop unwanted flow, and reduce the risk of vascular trauma due to snagging at the vascular opening. When deployed, the tip 310 can match the diameter of the blood vessel and have sufficient radial force to seal with the vessel or create sufficient flow restriction, thereby applying most of the suction to the blood and thrombus distal to the opening rather than the fluid proximal to the tip.

[0061] In another example, the support tube 100 may have a distal surface 115 connected to an expandable mouth tip 410, which may have a radial array of staves or strands organized into a closed cell braid, as shown in Figure 9. The braid is connected to the flat surface 115 of the support tube 100, flares out to the distal end 414, and, as shown when unrestrained, forms a substantially conical or funnel-shaped form around the longitudinal axis 111, which can expand as it exits the outer sheath or catheter.

[0062] The braided array may be fabricated from wire or cut from a shape memory alloy, thereby allowing the mouth to be thermocured to self-expand from a folded delivery form to an extended, unfolded form. The mouth tip 410 can be bonded or otherwise joined to the distal end 114 of the support tube 100. In one example, the braided tip 410 may be manufactured to have a single circumferential joint or ring collar for attaching the support tube 100. Alternatively, individual strands of the braid may be bonded directly to the distal surface 115 of the tube or embedded within a polymer jacket.

[0063] In another example, the expandable tip 410 may be a closed cell mesh array having a continuous polygonal pattern made up of triangular or quadrilateral cell holes 415 interlocked via the vertices of adjacent cells in the mesh. The pattern may be one of those commonly seen in stent applications, where a minimally invasive mesh is used to support and retain an open vascular passage. In some cases, an elongated quadrilateral pattern forms the cell holes 415, with local array peaks marking common vertices. The pattern can be repeated axially and radially, and the most distal array peaks of adjacent holes 415 can be joined by a non-traumatic, curved distal hoop or crown 412 to mark the distal end 414 of the expandable tip 410.

[0064] A method for manufacturing a catheter using the disclosed expandable laser-cut support tube 100 is graphically shown in Figures 10A to 10E and further illustrated in the flow chart of Figure 11. Figure 10A shows a low-friction liner 160 positioned on a support mandrel 10. The mandrel may often be silver-plated copper (SPC), which is commonly used in these applications. Alternatively, a ductile material (such as PEEK) may be used, which is stretched to a narrow diameter so that the mandrel can be removed after the completion of the catheter assembly. Further mandrel materials may be nylon-coated copper or nylon-coated steel.

[0065] A laser-cut support tube frame 100 is formed in Figure 10b, and this frame has a continuous longitudinal split seam 116, allowing the support tube frame to elastically expand radially. In some examples, the support tube frame 100 can be cut from NiTi or other shape memory superelastic alloys so that the solid-state transformation can be designed to specify the constrained and unconstrained diameters of the frame. This expansion allows the support tube 100 to have an inner diameter approximately the same size as the outer diameter 162 of the liner 160. Ribs 118 can be positioned and varied along the longitudinal axis 111 so that the support tube 100 has good compressibility and columnar strength near the proximal end 112 and excellent lateral flexibility near the distal end 114. In some examples, an expandable tip 310 can be formed or attached to the distal end 114 of the support tube 100.

[0066] In Figure 10c, the support tube frame 100 is radially expanded at the seam and slides over an oversized mandrel 20. The oversized mandrel 20 can be, for example, at least 0.005 inches larger than the outer diameter 162 of the inner liner 160 on the applicable mandrel 10. The support tube 100 is then cold-treated (ideally with a martensitic finish (M)). f By cooling it to near or below 2°C, the support tube material can be transformed into the martensite phase. In another example, the support tube 100 can be cooled first and then unfolded on an oversized mandrel 20. If kept cooled, the support tube 100 can maintain its expanded shape when removed from the oversized mandrel 20 due to a reversible solid-state transformation to martensite.

[0067] Alternatively, the cooling step can be eliminated by placing a thin outer metal sleeve (not shown) around the oversized mandrel 20. The support tube 100 is elastically expanded on the sleeve / oversized mandrel assembly, allowing the oversized mandrel to be removed. The sleeve radially restrains the support tube, allowing it to slide on the inner liner 160 on the mandrel 10. Once the sleeve support is removed, the support frame 100 can contract on the inner liner 160.

[0068] The expanded support tube 100 can be slid over the inner liner 160 on the SPC application mandrel 10, as shown in Figure 10d. Without expanding the support tube, this step would generate too much friction, making it impossible to form a reliable and repeatable interface between the support tube and the liner. Once in place and concentric with the liner 160, the outer polymer layer 180 can be applied over the support tube 100 (Figure 10e). Layer 180 can be a series of separate axial polymer extruded materials that can be reflowed or laminated in place as outer jackets 183, 184, and 185. The applied heat can allow the outer polymer to fill the interstitial areas between the rib supports of the support tube.

[0069] A similar process is outlined in the method flow chart of Figure 11. The steps of this method can be implemented by either exemplary devices described herein and known to those skilled in the art, or by suitable alternatives. This method may have some or all of the steps described, but in many cases the steps can be carried out in a different order than those disclosed below.

[0070] Referring to Figure 11, Method 11000 may have step 11010 of positioning an inner liner around a first application mandrel. The liner may be PTFE or a similar low-friction material. The mandrel may be sized to be approximately equal to the desired inner diameter of the finished catheter. Step 11020 may then include forming a laser-cut support tube structure as previously described herein. The support tube may be nitinol or another shape-memory superelastic alloy, but may not be limited to these, and may be cut from a single continuous hypo tube. The cut portion may form a series of circumferentially discontinuous ribs, the discontinuous portions of which align to form one or more longitudinally continuous seams along the length of the support tube, as seen in Figure 10A and step 11030. The ribs may be connected by spines that extend axially and follow a circuit path around the ribs of the support tube in a nonlinear manner on the alternating sides of the seams. This structure may allow for some radial expansion of the support tube while providing good axial resistance to both tensile and compressive loads. The inner diameter of the support tube can be the same as or slightly smaller than the outer diameter of the low-friction inner liner, so that the components are arranged concentrically when the catheter is assembled.

[0071] In step 11040, the axial seam is stretched to elastically expand the support tube, allowing the support tube to be positioned on a second oversized mandrel. In some examples, the oversized mandrel can be sized such that the expanded inner diameter of the support tube frame is slightly larger than the outer diameter of the inner liner on the applicable mandrel. In some examples, the ID can be about 0.003 to 0.005 inches larger than the OD of the liner. Once the support tube is expanded on the oversized mandrel, at least A f Below the temperature, ideally the material's M f By cooling to a temperature close to or below the temperature, a phase change to martensite can be induced. Since the martensite phase is thermodynamically stable, the support tube can be kept cool and its expanded state maintained when the second oversized mandrel is removed in step 11060.

[0072] Next, the expanded support tube can be slid around the inner liner on the first application mandrel in step 11070 and positioned around it. Then, a series of outer polymer jackets of various durometer hardness can be reflowed onto the support tube (step 11080). The jackets may be axially continuous, radially continuous, or some combination. The flow of jacket material may allow them to encapsulate the rib supports of the support tube and bond with the inner liner. Once the assembly is complete, the first application mandrel can be removed in step 11090.

[0073] The present invention is not necessarily limited to the examples described and may vary in configuration and detail. The terms “distal” and “proximal” are used throughout the above description and mean location and direction relative to the treating physician. Thus, “distal” or “distal” refers to a location away from the physician or a direction away from the physician. Similarly, “proximal” or “proximal” refers to a location close to the physician or a direction toward the physician. Furthermore, unless the context clearly specifies otherwise, the singular forms “a,” “an,” and “the” include multiple referents.

[0074] In this specification, the terms “about” or “approximately” used with respect to any number or range of numbers indicate a suitable dimensional tolerance that enables a part or set of components to function in accordance with its intended purpose as described herein. More specifically, “about” or “approximately” may refer to a range of values ​​within ±20% of the listed values; for example, “about 90%” may refer to a range of values ​​between 71% and 99%.

[0075] Technical terms are used for clarity when describing exemplary embodiments. As a result, not all possible combinations are enumerated, and such modifications are often obvious to those skilled in the art and are intended to fall within the scope of the following claims. Each term is intended to have its broadest meaning as understood by those skilled in the art and is intended to include all technical equivalents that operate in a similar manner to achieve a similar purpose without departing from the scope and spirit of the invention. It should also be understood that references to one or more steps of a method do not preclude the existence of additional step steps or step steps intervening between those explicitly identified steps. Similarly, some steps of a method may be carried out in an order different from that described herein without departing from the scope of the disclosed art.

[0076] [Implementation Method] (1) A flexible catheter comprising a support tube, a proximal end, and a distal end, wherein the support tube is An inner liner arranged around the longitudinal axis of the support tube, A series of axial interlock segments, comprising multiple circumferentially discontinuous ribs, forming a substantially tubular profile along the longitudinal axis, The interlock segment comprises one or more axial seams formed by the alignment of circumferentially discontinuous ribs, A flexible catheter wherein one or more axial seams allow the support tube to be radially expanded to an expanded inner diameter larger than the outer diameter of the inner liner. (2) Each of the interlock segments is A top half having a pair of inset teeth extending from each rib support, A bottom half having a pair of outset teeth extending from each rib support and defining the receiving space, A catheter according to Embodiment 1, comprising the following features. (3) The catheter according to Embodiment 2, wherein the receiving space of the bottom half is configured to interface with the inset teeth of the top half, so that when the support tube is assembled, the top half and the bottom half are juxtaposed with each other and radially separable from each other by one or more axial seams. (4) The catheter according to Embodiment 2, wherein the one or more axial seams are a continuous gap defined by the periphery of the interface between the receiving space of the bottom half and the inset teeth of the top half. (5) The catheter according to Embodiment 2, wherein the inset teeth and the outset teeth have a triangular or quadrilateral shape.

[0077] (6) The catheter according to Embodiment 2, wherein the inset teeth and the outset teeth are provided with L-shaped projections. (7) The catheter according to Embodiment 1, further comprising spines connecting each of the ribs in the axial direction, wherein the spines conform to a nonlinear profile. (8) The catheter according to Embodiment 1, wherein the distal end has a plane substantially perpendicular to the longitudinal axis, which is configured to connect to a catheter port configured for performing an intravascular procedure. (9) The catheter according to Embodiment 1, wherein the contour of one or more axial seams conforms to a nonlinear profile. (10) The catheter according to Embodiment 1, wherein the first segment pitch measured between adjacent interlock segments of a first pair is different from the second segment pitch measured between adjacent interlock segments of a second pair.

[0078] (11) A flexible support tube for a catheter shaft, wherein the support tube is A laser-cut framework for a support column comprising substantially circular ribs distributed along the longitudinal axis of the support tube, wherein the ribs comprise one or more circumferential discontinuities around the support tube, The support tube comprises one or more axial seams formed from the alignment of the circumferential discontinuities of the ribs, which are configured to allow radial expansion of the support tube, The ribs of the support frame form a series of axial interlock segments having substantially tubular profiles along the longitudinal axis. Each of the aforementioned interlock segments is A top half having a pair of inset teeth extending from each rib support, A bottom half having a pair of outset teeth extending from each rib support and defining the receiving space, A flexible support tube equipped with [a specific feature]. (12) The support tube according to Embodiment 11, wherein the interlock segments are aligned so that when the support tube is assembled, each pair of inset teeth of the top half and each pair of outset teeth of the bottom half are juxtaposed with each other and radially separable by the one or more axial seams. (13) The support tube according to embodiment 12, wherein the one or more axial seams are a continuous gap defined by the periphery of the interface between the outset teeth of the bottom half and the inset teeth of the top half. (14) The support tube according to embodiment 12, wherein one or more axial seams have a nonlinear profile. (15) The support tube according to embodiment 12, wherein the inset teeth of each top half and the outset teeth of each bottom half (104) are provided with projections parallel to the longitudinal axis of the support tube.

[0079] (16) The support tube according to embodiment 12, wherein the engagement of the inset teeth with the outset teeth restricts the axial expansion of the support tube. (17) The support tube according to Embodiment 11, wherein the first segment pitch measured between adjacent interlock segments of a first pair is different from the second segment pitch measured between adjacent interlock segments of a second pair. (18) The support tube according to embodiment 11, wherein the width of the first rib of one rib support is different from the width of the second rib of another rib support. (19) A method for manufacturing a catheter, wherein the method is The steps include: positioning the inner liner around the first application mandrel, The steps include forming a support tube having an axial seam that allows for radial expansion of the support tube, A step of expanding the support tube by arranging the support tube on a substantially tubular second oversized mandrel and extending the axial seam, wherein the oversized mandrel is sized to have an outer diameter slightly larger than the outer diameter of the inner liner, The steps include: cooling the support tube to a temperature below the austenite finishing temperature; The steps include removing the second extra-large mandrel from the support tube, The steps include arranging the radially expanded support tube around the inner liner and the first application mandrel, The steps include reflowing or laminating multiple outer polymer jackets onto the support tube, A method comprising the step of removing the first application mandrel when the inner liner and the support tube are bonded by the outer polymer layer. (20) The method according to embodiment 19, further comprising the step of laser cutting the support tube to form a plurality of circumferentially discontinuous ribs, and aligning the circumferentially discontinuous portions to form the axial seam.

Claims

1. A flexible catheter comprising a support tube, a proximal end, and a distal end, wherein the support tube is An inner liner arranged around the longitudinal axis of the support tube, A series of axial interlock segments, comprising multiple circumferentially discontinuous ribs, forming a substantially tubular profile along the longitudinal axis, The interlock segment comprises one or more axial seams formed by the alignment of circumferentially discontinuous ribs, The one or more axial seams enable the support tube to be radially expanded to an expanded inner diameter larger than the outer diameter of the inner liner, Each of the aforementioned interlock segments is A top half having a pair of inset teeth extending from each rib support, A bottom half having a pair of outset teeth extending from each rib support and defining the receiving space, Equipped with, A catheter in which the inset teeth and the outset teeth are equipped with L-shaped projections.

2. The catheter according to claim 1, wherein the receiving space of the bottom half is configured to interface with the inset teeth of the top half, so that when the support tube is assembled, the top half and the bottom half are juxtaposed with each other and radially separable from each other by one or more axial seams.

3. The catheter according to claim 1, wherein the one or more axial seams are a continuous gap defined by the periphery of the interface between the receiving space of the bottom half and the inset teeth of the top half.

4. The catheter according to claim 1, wherein the inset teeth and the outset teeth have a triangular or quadrilateral shape.

5. The catheter according to claim 1, wherein the distal end has a surface substantially perpendicular to the longitudinal axis, configured to connect to a catheter port configured for performing an intravascular procedure.

6. The catheter according to claim 1, wherein the first segment pitch measured between adjacent interlock segments of a first pair is different from the second segment pitch measured between adjacent interlock segments of a second pair.

7. A flexible support tube for a catheter shaft, wherein the support tube is A laser-cut framework for a support column comprising substantially circular ribs distributed along the longitudinal axis of the support tube, wherein the ribs comprise one or more circumferential discontinuities around the support tube, It comprises one or more axial seams formed from the alignment of the circumferential discontinuities of the rib, which is configured to allow radial expansion of the support tube, The ribs of the framework of the support column form a series of axial interlock segments having substantially tubular profiles along the longitudinal axis. Each of the aforementioned interlock segments is A top half having a pair of inset teeth extending from each rib support, A bottom half having a pair of outset teeth extending from each rib support and defining the receiving space, Equipped with, When the interlock segments are aligned, the support tube is assembled such that each pair of inset teeth of the top half and each pair of outset teeth of the bottom half are aligned with each other and are radially separable by one or more axial seams. A support tube in which the inset teeth of each top half and the outset teeth of each bottom half are provided with projections parallel to the longitudinal axis of the support tube.

8. A flexible support tube for a catheter shaft, wherein the support tube is A laser-cut framework for a support column comprising substantially circular ribs distributed along the longitudinal axis of the support tube, wherein the ribs comprise one or more circumferential discontinuities around the support tube, It comprises one or more axial seams formed from the alignment of the circumferential discontinuities of the rib, which is configured to allow radial expansion of the support tube, The ribs of the framework of the support column form a series of axial interlock segments having substantially tubular profiles along the longitudinal axis. Each of the aforementioned interlock segments is A top half having a pair of inset teeth extending from each rib support, A bottom half having a pair of outset teeth extending from each rib support and defining the receiving space, Equipped with, When the interlock segments are aligned, and the support tube is assembled, each pair of inset teeth of the top half and each pair of outset teeth of the bottom half are positioned side by side and are radially separable by one or more axial seams. A support tube in which the engagement of the inset teeth with the outset teeth restricts the axial expansion of the support tube.

9. The support tube according to claim 7 or 8, wherein the one or more axial seams are a continuous gap defined by the interface between the outset teeth of the bottom half and the inset teeth of the top half.

10. The support tube according to claim 7 or 8, wherein the first segment pitch measured between adjacent interlock segments of a first pair is different from the second segment pitch measured between adjacent interlock segments of a second pair.

11. The support pipe according to claim 7 or 8, wherein the width of the first rib of one rib support is different from the width of the second rib of another rib support.

12. A method for manufacturing a catheter, wherein the method is The steps include: positioning the inner liner around the first application mandrel, The steps include forming a support tube having an axial seam that allows for radial expansion of the support tube, A step of expanding the support tube by arranging the support tube on a substantially tubular second oversized mandrel and extending the axial seam, wherein the oversized mandrel has an outer diameter slightly larger than the outer diameter of the inner liner; The steps include: cooling the support tube to a temperature below the austenite finishing temperature; The steps include removing the second extra-large mandrel from the support tube, The steps include arranging the radially expanded support tube around the inner liner and the first application mandrel, The steps include reflowing or laminating multiple outer polymer layers or jackets onto the support tube, A method comprising the step of removing the first application mandrel when the inner liner and the support tube are bonded by the outer polymer layer or jacket.

13. The method according to claim 12, further comprising the step of laser cutting the support tube to form a plurality of circumferentially discontinuous ribs, and aligning the circumferentially discontinuous portions to form the axial seam.

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