Catheter design for enhancing column strength

Abstract

The invention is entitled "Catheter Design for Enhanced Column Strength". The purpose of the designs presented can be to create a catheter with variable flexibility and kink resistance for vascular applications. These designs benefit from good compression and tensile stiffness. Braided wire support structures can be placed around an inner liner and outer layer with multiple variable stiffness outer jackets. Metal reinforcement layers can be cut from hypotube and used as the primary structure for catheter stiffness, reducing the reliance and number of jackets to transition stiffness changes along the length of the catheter. The metal reinforcement layers can have one or more ribbon cut sections and one or more axial hole patterns laser cut into the hypotube to gradually evolve the stiffness from a proximal region with higher column stiffness and a distal region with greater lateral flexibility. The polymer jackets can be back-welded to join the structures together.

Description

Technical Field

[0001] This disclosure relates generally to devices and methods for insertion into blood vessels during endovascular medical treatment. More specifically, this disclosure relates to catheters with improved flexibility while maintaining axial stiffness. Background Technology

[0002] Catheters offer a wide range of functions in endovascular medical treatments. They are typically small tubular devices made of medical-grade materials that can be inserted into the body and used to deliver medications or other devices, perform surgical procedures, remove blockages from blood vessels, and for various other purposes. Different sections of the catheter can be customized for specific applications by changing the materials or modifying the way it is manufactured.

[0003] For most intravascular catheters, a small outer diameter and a large inner diameter and lumen are preferred. A small outer diameter makes insertion easier and allows access to more distal sites, such as neurovascular structures. A large lumen allows for the insertion and delivery of larger medical devices and / or the guidance of larger volumes of fluid or aspirate through the lumen. To minimize the outer diameter while maximizing the lumen volume, a relatively thin catheter wall thickness is desirable, while still maintaining excellent flexibility and good resistance to elongation and compression.

[0004] Numerous access challenges exist, making access to the target site difficult. In cases involving navigation of the aortic arch (such as in patients with coronary artery occlusion or cerebral occlusion), the arch configuration in some patients makes positioning the guiding catheter challenging. Beyond the arch, access to the neurovascular bed using conventional techniques is particularly challenging because the target vessel is small in diameter, located distantly relative to the insertion site, and is highly tortuous. It is not uncommon for the catheter to be navigated through a winding path using multiple loops, where the vessel segment may have several rapid, consecutive extreme bends within a few centimeters of travel, potentially leading to kinking. The increasingly narrow accessibility of the arterial system can result in fragile vessels that are easily damaged by inflexible or large-shaped devices.

[0005] Catheters used in these procedures can be challenging to design because they must be sufficiently rigid at the proximal end to maintain maneuverability while also allowing for comfortable manipulation by the user, while remaining flexible in the more distal portion to withstand high flexural strain and advance through cuffs and increasingly smaller vessels without causing trauma. For these reasons, size, kink resistance, trackability, and flexibility are key design parameters typically associated with catheters used in these procedures, and managing the transition from softer to more rigid materials and areas is crucial for successful patient outcomes.

[0006] Several designs and methods have been proposed for guiding catheters to the target site. In one approach, the catheter is fitted onto and slid along a guidewire used to access the target site. However, thin guidewires almost always have greater accessibility and distal flexibility than catheter fittings. Newer designs have been proposed that utilize various methods to alter the stiffness between the proximal and distal portions of the catheter, such as polymer tubing, which typically features braids or coils involving threads or strips of other reinforcing materials. Currently, most of these catheters transition from a more rigid to a softer material by changing the configuration of the braided components (changing the braid PIC count or coil pitch) or by altering the durometer hardness of the surrounding polymer material. However, excessively large changes in durometer hardness between adjacent polymer segments can create kinks at the transition. Therefore, current catheter designs are limited to transitions with similar polymer hardness values ​​to mitigate the tendency for kinks at such junctions, resulting in a large number of polymer segments, increasing cost and manufacturing complexity.

[0007] The coils of the braided yarn or strip used to reinforce the polymer segments are typically made of very small, continuous, highly elastic metal or stainless steel. The sufficiently small size or diameter of the coils or braids can easily lead to kinking and make it difficult to manufacture with the consistency required for a uniform product. Kinking of the reinforcing layer can increase the risk of the metal material cutting into the surrounding polymer at the kink. These materials also add to cost and complexity.

[0008] Furthermore, in thrombectomy procedures, aspiration catheters need to be highly flexible to access distant occlusions, but also benefit from good compressive stiffness (for maneuverability and stability and integrity when the clot retrieval device is withdrawn) and good tensile stiffness (to avoid stretching and deformation when placed under tension, such as when withdrawn into the outer sheath, while maintaining a large clot). Combining these characteristics without significant trade-offs has always been challenging for traditional catheter designers. Therefore, catheter designs often tend to sacrifice proximal column strength for flexibility and trackability.

[0009] This design aims to provide an improved catheter structure to address the aforementioned deficiencies. Summary of the Invention

[0010] The present disclosure relates to a catheter having features for controlling axial and lateral stiffness, as well as a stiffness transition along the catheter's axial length. The catheter may be tubular, having a proximal end, a distal end, and a longitudinal axis. The catheter may have a low-friction liner, a braided support structure surrounding the liner, a metallic stiffness transition reinforcement layer, and a series of outer polymer layers or sheaths. The outer sheath may bond the reinforcement layers to the braided support structure. Near the distal end, a soft polymer tip may extend from the end of the braided support structure.

[0011] This design can feature excellent column strength in the proximal portion of the catheter shaft and a transition to an extremely flexible distal segment. A metallic reinforcing layer can be configured to balance the stiffness transition within the catheter. These designs achieve the desired stiffness transition along the axis by altering the configuration of these features above different axial segments of the shaft. This transition from a softer to a harder material is crucial for the successful use of catheters in vascular applications.

[0012] In some examples, the catheter may be a tube having a proximal end, a distal end, and a longitudinal axis. The catheter may be constructed as a series of layers. For example, the catheter may have an inner liner, a braided support structure surrounding the inner liner, and a tubular metal reinforcement layer surrounding the braided support structure, the tubular metal reinforcement layer being configured to impart at least a portion of different stiffness characteristics to the catheter. Multiple outer polymer sheaths may be used to join the aforementioned structures together. In one example, the catheter may also have a soft polymer end extending distally from the end of the braided support structure.

[0013] The braided support structure can be made of various materials. In one example, the wire is stainless steel. In another example, the wire is nitinol or some other superelastic alloy. The wire diameter can be approximately 0.0015 inches or some other size. Other factors, such as the PIC count of the braid, can be changed to adjust the flexibility of the catheter. The first PIC count in the proximal portion of the braided support structure can differ from the second PIC count in the distal portion of the braided support structure. In one example, the first PIC count can range between 20 and 70. In another example, the second PIC count can range between 120 and 200.

[0014] The tubular metal reinforcement layer can be cut from a single continuous thallium tube. In one example, the tubular reinforcement layer can extend the entire distance between the proximal and distal ends of the conduit. In another example, the reinforcement layer can extend from the proximal end and terminate at an intermediate distance along a braided support structure proximal to the distal end. The tubular reinforcement layer can be divided into axially spaced segments of removed material with the same or different cutting patterns, which are configured to impart different stiffness properties to at least a portion of the conduit. The cutting patterns can be, for example, holes, slots, strips, and / or other features cut into the layer. The pattern and the density of the pattern can vary along the axial segments of the conduit.

[0015] In some examples, at least one or more axial sections of the catheter may have one or more strip-cut sections that are longitudinally helically cut around a longitudinal axis. The size and layout of the strip-cut sections can be adjusted to better transition the stiffness variations of the various axial sections of the catheter. For example, one or more strip-cut sections may have an axial portion with a first strip width different from a second strip width of another axial portion of the same strip-cut section. In another example, a strip-cut section may have an axial portion with a first pitch different from a second pitch of another axial portion of the same strip-cut section.

[0016] In other examples, one or more axial segments may have an axial hole pattern cut from the tubular reinforcing layer. In some examples, the hole pattern may have a gradient of varying pore density, where a larger distance between the holes means that the residual material of the tubular reinforcing layer provides greater column strength to those locations of the conduit. Additionally, the holes in the hole pattern may have different diameters and / or shapes, both within a given hole pattern or between two different hole patterns.

[0017] The hole pattern can also be a helical pattern arranged around a longitudinal axis. The helical pattern can have a variable pitch, allowing more or less bare metal to be present in certain axial portions of the reinforcing layer. In one example, the helical pattern of the hole may have an axial portion where the first pitch of this axial portion differs from the second pitch of another axial portion of the helical pattern. In another example, the helical pattern may have an axial portion where the first helix angle differs from the second helix angle of another axial portion of the helical pattern.

[0018] Changing the pitch and helix angle does not sacrifice column strength in the axial direction because the metal reinforcement layer remains solid throughout. These changes to the hole pattern also mean achieving a material gradient removal. In some examples, multi-layered hole pattern types with reduced / increased dimensions can be used to make the stiffness transition in the conduit even smoother.

[0019] In one example, the catheter for vascular access may have a proximal end, a distal end, and a longitudinal axis extending between the proximal and distal ends. The catheter may have a braided support structure surrounding an inner liner, a metallic tubular reinforcement layer, and one or more outer polymer sheaths.

[0020] In some examples, the braided support structure may extend from the proximal end of the catheter to a point near the distal end. The braid itself may be characterized by a single PIC count or by having a variable PIC count in different axial portions of the catheter. The braid may also have different braid angles to alter the bending characteristics along the catheter axis.

[0021] A tubular metal reinforcing layer may be disposed around the braided wire support structure. The reinforcing layer may extend the entire length of the wire support structure, or extend from a proximal end to a portion of the wire support structure. In some examples, the tubular metal reinforcing layer may be formed from a single thallium tube of shape memory alloy, stainless steel alloy, or other suitable material.

[0022] At least the proximal portion of the reinforcing layer may have one or more axial hole patterns cut into the layer, the axial hole patterns having a gradient of varying hole density. In one example, the hole pattern may be a helical pattern arranged around the longitudinal axis. In another example, the gradient may be achieved by varying the diameter and / or spacing of the hole pattern, which may be a straight axial geometry or a helical pattern.

[0023] In another case, the reinforcing layer may have portions with one or more strip-cut sections configured as longitudinally extending helices around a longitudinal axis. Similar to other examples, the strip-cut sections may have design variables, such as strip width and pitch, that can vary along the axial length of the section to adjust the stiffness contribution of the reinforcing layer. The helix angle of the strip coils relative to the axis can also be adjusted for this purpose.

[0024] The transition from, for example, one axial hole pattern to another, or from a hole pattern to an adjacent strip cut segment, can lead to stress concentration and potential kinks. To avoid kinks and to integrate the stiffness transition between various hole patterns and strip cut segments, the metallic reinforcing layer can also include transition features at and around the interface of adjacent axial segments. In some examples, the transition feature may be an intermediate transition hole to integrate the progression from the hole pattern to the strip cut segment. In other examples, slots may be cut into the strip to bridge the displacement from one strip cut segment with a specific size to another strip cut segment with a different size.

[0025] In another example, one or more outer polymer sheaths may be disposed around the tubular reinforcing layer. The hardness of at least one outer polymer sheath may differ from that of adjacent polymer sheaths to modulate and transition axial stiffness and bending characteristics in different sections of the conduit. For example, the outer sheaths may have varying hardness to form a proximal portion with greater column stiffness and a distal portion with greater lateral flexibility. The sheaths may be remelted and welded over the underlying structure to bond the reinforcing layer to the braided wire support structure. When heat is applied, the polymer of the sheath may flow through the holes and gaps in one or more axial hole patterns within the strip-cut sections of the metallic reinforcing layer.

[0026] Other aspects and features of this disclosure will become apparent to those skilled in the art after viewing the following detailed description in conjunction with the accompanying drawings. Attached Figure Description

[0027] The foregoing and other aspects of the invention will be further discussed with reference to the following description and the accompanying drawings. The drawings are not necessarily drawn to scale, but rather to illustrate the principles of the invention. The drawings depict one or more specific embodiments of the apparatus of the invention by way of example only, and not by way of limitation.

[0028] Figure 1 This is a view of a conduit according to an aspect of the invention, the conduit having a metal tubular reinforcing layer for enhancing column strength;

[0029] Figure 2 An aspect according to the invention is shown Figure 1 A closer view of the proximal end of the catheter;

[0030] Figure 3 This is an example representation of the axial hole pattern of the metal reinforcing layer according to an aspect of the present invention;

[0031] Figure 4 An alternative axial hole pattern with a helical configuration according to an aspect of the invention is shown;

[0032] Figure 5 Another example of a metal reinforcing layer according to an aspect of the invention is shown;

[0033] Figure 6 A strip-shaped cutting segment for a reinforcing layer according to an aspect of the invention is depicted;

[0034] Figures 7A to 7B A possible example of a transition feature for a reinforcing layer according to an aspect of the invention is shown;

[0035] Figure 8 According to aspects of the present invention Figure 1 A closer view of the outer polymer sheath; and

[0036] Figure 9 According to aspects of the present invention Figure 1 A closer view of the distal end of the catheter. Detailed Implementation

[0037] The proposed designs are intended for use as extended catheter shafts with variable flexibility and kink resistance in vascular applications. These designs are flexible enough to access remote vascular occlusions while also benefiting from good compressive and tensile stiffness. The catheter may have a braided support structure serving as the trunk, with a low-friction liner disposed on the inner surface. An outer polymer layer or laminated sheath may cover the assembly.

[0038] These concepts require replacing the nearest-side plastic section of the catheter with a metal reinforcing shaft incorporating a tapered, striped section. To allow this component to integrate seamlessly with the rest of the catheter design, a progressive pattern of orifices and / or slots can be placed on the proximal portion of the metal shaft (proximal to the striped section). This allows one or more plastic sheaths to be placed over the entire metal reinforcing shaft and braided structure. By maintaining the entire solid hypotube, a seamless transition can be achieved by tapering the pattern of orifices, strips, and / or slots on the metal reinforcing layer without sacrificing axial column strength.

[0039] While the descriptions are often set 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 bodily access routes that require catheters with a high degree of adaptive stiffness. For example, microcatheters, which typically have a much smaller diameter than other catheters, can also be made using these concepts.

[0040] Approaching various intravascular vessels (whether coronary, pulmonary, or cerebral) involves well-known surgical procedures and the use of many routinely available commercially available accessory products. These products may include angiographic materials, rotary valves, and guidewires widely used in laboratory and medical procedures. Although not specifically mentioned by name, their function and exact construction are not described in detail when these or similar products are inevitably used in conjunction with the systems and methods of the present invention described below.

[0041] Specific examples of the invention will now be described in detail with reference to the accompanying drawings, wherein like reference numerals indicate functionally similar or identical elements.

[0042] Switch to the attached image. Figure 1 The image shows a catheter 100 for endovascular procedures in a patient's blood vessels. The support tube 100 can typically be a layered tubular frame with a proximal end 112 and a distal end 114, through which a longitudinal axis 111 extends. The innermost layer may be a liner 115 of PTFE or other low-friction material to facilitate the passage of auxiliary devices through the catheter lumen. Surrounding the liner 115 may be a braided support structure 120 having a braid or coil of threads or strips involving other materials.

[0043] The coils of the braid can be continuous, highly elastic metal or stainless steel wires with very small dimensions. The stiffness transition can be partially controlled by changing the configuration of the support structure 120 (e.g., changing the braid PIC count, wire diameter, or coil pitch). For example, the PIC count in the proximal portion of the braided support structure 120 can be less than the second PIC count in the distal region. In one case, a PIC count of 120 to 170 can be used in the proximal region of the support structure 120 to obtain good drivability. In another example, the first PIC count in one region can range from 20 to 70, while the second PIC count in the distal region can range from 120 to 200.

[0044] At least a portion of the length of the braided support structure 120 extending from the proximal end 112 of the conduit 100 may be a metallic tubular reinforcement layer 210. Layer 210 may be cut, for example, from a single continuous thallium tube of NiTi or another suitable alloy. The stiffness transition along the axial length of the conduit 100 can be managed by adjusting flexibility through progressive axial bore patterns 220 and / or ribbon-like helical segments 240 cut along various lengths of the thallium tube. The metallic tubular reinforcement layer 210 may be an alternative to the proximal portion of many current plastic conduit shaft designs. The metallic tubular reinforcement layer 210 may extend from the proximal end 212 to the distal end 214, which may terminate at a point proximal to the distal end 114 of the conduit 100. Beyond this termination, the liner 115 and the braided support structure 120 may extend distally before the conduit shaft terminates in the soft polymer end 10 at the distal end 114. During the procedure, the end of the catheter 100 may be marked with a radiopaque marker or a band 12 (such as platinum) near the end 10.

[0045] Similar to many current designs, the catheter retains the braided support structure as the backbone and adds an overlapping metal reinforcement layer 210. The use of the metal reinforcement layer 210 allows for the use of finer spacing threads in the braid. In some examples, the braided thread diameter can be approximately 0.0030 inches. In other examples, even finer threads of 0.0015 inches can be utilized. The braided support backbone 120 can also be covered by a series of axially oriented plastic tubular sheaths 180, 182. The sheaths can be made from various medical-grade polymers, such as PTFE, polyether block amides, etc. Or nylon. The material can be selected, for example, so that it is progressively harder and less flexible (expressed by hardness, flexural modulus, etc.) as it approaches the proximal end 112 of the conduit 100.

[0046] Figure 2 The text shows information from... Figure 1An enlarged view of the proximal portion of the catheter 100. The liner 115 may have an outer diameter 117 defining the inner lumen of the catheter around a longitudinal axis 111. The outer diameter 117 of the liner 115 may engage with the inner surface of the braided support structure 120, visible here through the axial hole pattern 220 of the overlapping metallic tubular reinforcement layer 210. The liner 115 may have a very limited thickness 116 to provide maximum lumen size for device passage and effective suction.

[0047] As shown, the axial hole pattern 220 on the proximal portion of the reinforcing layer 210 may be characterized by geometrically spaced large holes to leave significant solid material between the large holes on the reinforcing layer. This arrangement can maintain excellent axial stiffness near the proximal end 212, while one or more hole patterns 220 may have the characteristics of less material and greater lateral flexibility that can transition to the distal portion of the metal reinforcing layer 210.

[0048] The reinforcing layer 210 can be placed on top of the braided support structure 120 as if it were a polymer segment derived from another conduit design, and remelted or laminated in place to continue distally along the transition from metal to plastic. To optimally integrate the reinforcing layer into portions of the braided support structure 120 and the liner 115, a first polymer sheath 180 can cover the proximal region, such as... Figures 1 to 2 As shown. The first polymer sheath 180 can be a range of materials and hardnesses, depending on the characteristics of the underlying structure. For example, the hardness of the first polymer sheath 180 can be 55-70 Shore hardness (55D-70D), which allows the sheath and metal reinforcement layer 210 in this area to replace additional, harder 72D-80D polymer segments in existing catheter designs.

[0049] The characteristics of the single or multiple progressive axial hole patterns 220 of the metal reinforcement layer 210 can be modified in a variety of ways to achieve the desired flexibility and stiffness transition capabilities. Figure 3 An example of a metal reinforcement layer 210 is shown, which has a first hole pattern 222 near the proximal end 212 of the layer, a second hole pattern 226 located on the middle portion of the layer, and a third hole pattern 230 near the distal end 214.

[0050] The desired local stiffness characteristics of the metal-reinforced submersible 210 can be achieved by changing the hole diameter, the number of holes cut in the radial plane, and / or the spacing between the holes used in the hole patterns 222, 226, 230. This is by way of example, not limitation. Figure 3The illustrated thiopanel tube has five different orifice diameters, six transition zones, six different numbers of orifices in the radial plane, and eight different orifice spacings. Orifice patterns 222, 226, and 230 can each have multiple orifice sizes and spacings to adjust the transition between stiffness and pattern variations along the axial length of the tube, thereby preventing the formation of kinks.

[0051] In one example, the first hole pattern 222 may include holes having a first hole diameter 224. The holes may be 224 with a diameter of 1.00 mm and may have three holes (spaced 120 degrees) and / or four holes (spaced 90 degrees) in the radial plane. The second hole pattern 226 may have a second hole diameter 228 with a diameter of 1.00 mm, wherein there are six holes (spaced 60 degrees) in the radial plane. In another case, the second hole pattern 228 may have a second hole diameter of 0.75 mm, wherein there are eight holes (spaced 45 degrees) in the radial plane, or a combination of these two examples. The third hole pattern 230 near the distal end 214 may have a third hole diameter 232 with a diameter of 0.50 mm, wherein there are 12 holes (spaced 30 degrees) in the radial plane; and a fourth hole diameter 234 with a diameter of 0.25 mm, wherein there are 24 holes (spaced 15 degrees) in the radial plane, or a combination of these examples.

[0052] These designs may have transition patterns or features to bridge, for example, the stiffness transition between the first hole pattern 222 and the second hole pattern 226. Thus, a sample transition zone may have a pattern of four 1.25 mm holes per radial plane between the first pattern 222 (four 1.00 mm holes) and the second pattern 226 (six 1.00 mm holes). The axial length of this transition pattern can be very short, but a certain amount of material is removed from the submersible tube to ensure sufficient lateral flexibility in the boundary region between the patterns.

[0053] In another example, a seamless stiffness transition can be achieved by cutting holes in one or more tapered strips or spiral patterns into the hyaluronic acid tube of the tubular metal reinforcement layer 210, such as... Figure 4 As shown. Similar to other designs, the progressive tapered pattern removes varying amounts of material from the tubular metal reinforcement layer 210 to allow a gradual transition from hard metal to soft plastic in the duct shaft section. Radial flexibility can be achieved through a series of holes without sacrificing column strength, as the entire construction of the hyaluronic acid tube remains solid after cutting.

[0054] The most flexible distal portion of the sodium hypochlorite tube can be obtained by arranging the aperture pattern 220 into a dense spiral band around the longitudinal axis 111. By way of example, and not limitation, the sodium hypochlorite tube may have, for example... Figure 4The diagram shows a progressive spiral pattern, which may have a "large" first bore diameter 224 and a smaller second bore diameter 228, followed by a strip of bare metal. In one example, the first bore diameter 224 may be approximately 0.25 mm ID, and the second bore diameter 228 may be approximately 0.15 mm ID. The most flexible distal segment may have a relatively short third pitch 233, where the corrugated tube of the reinforcing layer 210 has the least amount of residual material. The pattern may follow a variable pitch spiral towards the proximal side, where more and more bare metal is retained to increase axial stiffness and strength. For example, the middle portion of the corrugated tube may have a second pitch 227 larger than the distal third pitch 233. The proximal end 212 of the reinforcing layer may have a spiral pattern with a maximum pitch 225, such that the tube has maximum stiffness around that location.

[0055] In another example, the metal reinforcement layer 210 may have a hole pattern pitch that varies continuously along the length of the segment of the submersible tube. This configuration can produce a varying stiffness distribution along the longitudinal length of the reinforcement layer 210.

[0056] Similarly, to facilitate transitions between different segments and pitches, the helix angle of the bore pattern 220 can vary along the length of the tubular metal reinforcing layer 210. For example, the first helix angle 235 near the proximal end 212 of the tube can be shallower and sharper than the more distal portion of the helical bore pattern. As the tube transitions to more distal pitches 227, 233, the helix angles 236, 237 can form gradually increasing obtuse angles with the longitudinal axis 111.

[0057] Figure 4 The reproduction in the design is a double-layered hole pattern. However, it is expected that 3, 4, or even 10 hole types can be used to reduce / increase the size, or to vary the spiral pattern to make the axial stiffness transition of the conduit even smoother.

[0058] The resulting structure exhibits considerable flexibility during bending while maintaining the stiffness and strength of the metal in the axial direction. Furthermore, incorporating the metal reinforcement layer 210 into the conduit structure provides significantly greater column strength compared to existing conduit designs that only incorporate metal braids or coils at the proximal end. Additionally, the disclosed design offers much greater resistance to kinking and will not be crushed along the proximal axis of the conduit.

[0059] Figure 5Another example of a tubular metal reinforcing layer 210 is depicted, which combines a variable aperture pattern and progressive strip coil segments to transition axial stiffness. A first axial aperture pattern 222 near the proximal end 212 of the reinforcing tube can transition into a helical second aperture pattern 226. The aperture pattern may be characterized by having apertures of the same diameter, different diameters, or a combination of both. The aperture pattern may lead to one or more strip-cut segments 240 within the middle and more distal reach range of the submersible tube 210.

[0060] While the hole patterns 222 and 226 can be variably cut in a manner similar to those previously described, the strip-cut section 240 can also be adjusted for stiffness. The strip section 240 can have characteristics similar to pitch and strip width, which can vary continuously along the length of the section, thereby forming a segmented or continuously varying stiffness distribution. Additionally, varying helix angles can be utilized along the length of the tube.

[0061] The bending stiffness of the reinforcing layer 210 can also be adjusted by changing the cutting width of the strip cutting section 240 and the coil width, or by changing the combination of the cutting width of the strip cutting section and the coil width. When the cutting width remains constant, such as the width of the laser beam, the coil width can be changed to adjust the bending stiffness. When the cutting width varies, the coil width can remain constant or vary, and a sheet of material can be removed using a laser. It should be understood that by using a cutting width equal to the cutting width of the laser beam, no sheet of material is removed, and manufacturing costs are significantly reduced. On the other hand, by using a laser to remove the sheet of material, greater variations in shaft design can be achieved. It should also be understood that a combination of the two methods can be used, allowing for the use of a more cost-effective cutting / processing device at the proximal end of the shaft, while reserving the more expensive method for specific distances at the distal end that may require more complex cutting to achieve the desired performance.

[0062] Alternatively, different materials can be used. For example, the proximal segment of the shaft can be cut from SS and joined to the distal segment cut from NiTi to reduce overall cost while providing the benefits of NiTi to the distal end of the device, where enhanced resilience against sharp bends is required, along with expansion and recovery properties. For such devices, the SS and NiTi segments can be joined directly by welding or by welding to a more weldable intermediate metal such as platinum. Alternatively, a laser-cut interlocking structure can hold the two cut tubes together longitudinally. Furthermore, the overall change from NiTi to harder materials such as SS or cobalt-chromium alloys can help metal thiocarbamates surpass polymers as the primary source of conduit stiffness.

[0063] One or more outer sheaths (not shown) hold the layers together in the radial direction. When one or more polymer sheaths are rejected above the catheter subassembly, the polymer can be melted into the orifices and the gaps between the slots and the ribbon coils to physically attach the metal thiopanel reinforcement layer 210 to the underlying metal braided component. The reinforcement layer then allows for an optimal transition to the more flexible distal portion of the catheter with other polymer components.

[0064] Figure 6 An example of a segment of a strip-cut section 240 is shown, which has a helical arrangement wound around a longitudinal axis 111 to provide a segment with specific flexibility advantages. The strip-cut section 240 can be cut such that the pitch and coil width vary along the axial length of the segment. For example, a first pitch 242 may be shortened or increased relative to a second pitch 246. Similarly, the strip section 240 may have a second coil width 247 that is wider than a first coil width 243. As the pitch and width vary, the helix angle formed by the strip coil with respect to the longitudinal axis 111 must also vary, such that the first helix angle 244 on the closer side is a larger obtuse angle than the second helix angle 248. It should be understood that parameters such as pitch and coil width can also be continuously tapered when cutting between the proximal end 212 and the distal end 214 of the metal reinforcement layer to avoid abrupt transitions in stiffness. Therefore, a high level of variability can be achieved by cutting sections of a winding by cutting individual strips, compared to keeping the pitch, coil width, and helix angle constant along the length of the section.

[0065] Therefore, the design of these features and dimensions can be adjusted to provide better trackability, thrust, and torque response closer to the proximal end 212 of the reinforcing layer 210. Similarly, near the distal end 214 of the assembly (where flexibility is more important), the strip-cut section 240 can have a spacing between turns that transitions to a progressive pitch to better optimize those physical capabilities.

[0066] During prototype testing of several proposed designs, additional features for improving performance were discovered. When the strip-cut section 240 is joined proximally to the hole patterns 222, 226, kink points can potentially form if the metal reinforcement layer 210 (hypoallergenic tube) constitutes a significant portion of the conduit stiffness. This is due to stress concentration caused by geometrical differences between the laser-cut features. If these differences are sufficiently pronounced, the metal strip-cut section 240 can cut into the outer polymer sheath, causing it to split and / or separate from the structure. Furthermore, even with a fillet radius, cracks can form at the corners of the proximal ends of the strip-cut section 240, where the metal hypoallergenic tube transforms into solid metal with the corresponding hole pattern. Although the strip-cut section 240 can have a continuous tapered shape (the width of the metal strip gradually increases in the proximal direction), the jump from the strip to the hole pattern may be too abrupt, thus making kink / breakage points unavoidable.

[0067] Figure 5 and Figures 7A to 7B This demonstrates that transition features easily incorporated into the design can prevent force concentration from the strip segment to the perforated configuration during compressive and bending loads. If the amount of material cut away to form the strip segment 240 is constant (from distal to proximal within the strip segment), the concentration could be more severe. Therefore, the purpose of transition features could be to provide a better and more flexible transition between the strip segment and the perforated segment of the submersible tube by allowing additional degrees of freedom of movement.

[0068] In the example shown, the proximal end of the strip cut segment 240 can evolve into a solider thallium tube of the reinforcing layer 210 by including one or more transition holes 260. The transition holes 260 can begin at the proximal stop of the cut between the strip coils, as... Figure 5 and Figure 7A As shown, material is removed to contribute to flexibility, rather than being removed continuously around the circumference of the tube. This pattern allows for material removal similar to that used to form the strip cut section 240, but now leaves some material (metallic spaces between the cut holes). The transition hole 260 can also form part of the second hole pattern 226, since the more geometrically shaped first hole pattern 222 does not necessarily have to begin immediately after the strip section 240 is completed.

[0069] Similarly, once the strip-cut section 240 reaches a larger, closer second coil width 247 than the target width, the transition feature of the helical cutting slot 262 can be formed within the remaining closer metal strip, such as... Figure 5 and Figure 7BAs shown. This allows for a certain degree of freedom of motion in wider strip segments, but not so much that the segments lose a large distribution of bending stiffness within the strip segment 240 (the segment can behave less like a strip and more like a solid body, such as...). Figure 5 (As shown).

[0070] As mentioned, multiple outer polymer sheaths can be combined to form the outer layer of catheter 100. Figure 8 It describes from Figure 1 The example shown is a close-up view of the transition from the first polymer sheath 180 to the second polymer sheath 182 on the proximal side. Using a laser-cut metal reinforcement layer 210 to manage the stiffness transition within the catheter shaft implies less dependence on the material properties of the various polymer sheaths. Current catheter designs are typically limited to polymer stiffness transitions with similar values ​​to mitigate the tendency for kinking at such joints. Therefore, the metal reinforcement layer 210 simplifies catheter construction and assembly due to a reduced number of components, allowing for a greater difference in stiffness between the first sheath 180 and the second sheath 182. Designs incorporating the reinforcement layer 210 can also utilize one or two polymer segments, whereas other current designs may require up to 12 polymer segments to provide a sufficient transition along the longitudinal length and prevent kinking between segments. Therefore, the disclosed design uses fewer sheaths along the length of the catheter shaft, thereby eliminating some of the adjacent joints between sheaths of different stiffness.

[0071] The outer polymer sheath 180 and 182 can be made of various medical-grade polymers, such as PTFE and polyether block amide. Or nylon. The material can be selected, for example, such that the proximal sections are generally harder and less flexible (expressed by hardness, flexural modulus, etc.) as they approach the proximal end 112, to increase the column strength and maneuverability of the catheter. Similarly, more flexible sections can be used toward the distal end.

[0072] As in other examples, the second polymer sheath 182 can be reflow welded on top of the underlying structure. Due to the desired more flexible distal portion surrounding the conduit shaft, the second polymer sheath 182 can be made of a softer material than that used for the first polymer sheath 180. In one example, the second sheath 182 can be of low hardness. (25D-40D). In another example, the second sheath 182 can be a low-hardness urethane or NeuSoft. TM (42-73 Shore A hardness). The transition between sheaths can be tapered or slotted to provide a more seamless transition between the flexibility distributions of adjacent sheaths in a longitudinal series.

[0073] The braided support structure 120 may continue distally to the strip-cut section 240 to terminate near the distal end 114 of the catheter 100, such as... Figure 9 As shown. Therefore, the distal portion of the catheter may have only a liner 115, a braided structure 120, and a second polymer sheath 182. A radiopaque marking tape, which may be platinum or other suitable material, may be coiled or otherwise attached to mark the distal end 114 of the catheter 100 during protocol. The distal end may have a very soft polymer tip 10 surrounding the liner 115 and the longitudinal axis 111. The tip 10 may be NeuSoft. TM Or other suitable engineered thermoplastic materials that offer good elasticity and abrasion resistance, while providing UV stability and barrier properties against moisture and oxygen. Although such materials typically have a standard hardness of 42-73 Shore A, this range can be extended to meet design specifications through formulation.

[0074] The invention is not necessarily limited to the described examples, the configurations and details of which may vary. The terms “distal” and “proximal” are used throughout the foregoing description and refer to position and orientation relative to the treating physician. Similarly, “distal” or “towards distal” refers to a position away from the physician or in a direction away from the physician. Likewise, “proximal” or “towards proximal” refers to a position close to the physician or in a direction toward the physician. Furthermore, unless the context clearly indicates otherwise, the singular forms “an,” “a,” and “the / described” include plural references.

[0075] As used herein, the term “about” or “approximately” for any numerical value or range indicates a suitable dimensional tolerance that allows a collection of parts or components to achieve the intended purpose as described herein. More specifically, “about” or “approximately” may refer to a range of ±20% of the enumerated values, for example, “about 90%” may refer to a range of values ​​from 71% to 99%.

[0076] In describing the example embodiments, terminology is used for clarity. Without departing from the scope and spirit of the invention, each term is intended to be contemplated for its broadest meaning as understood by one skilled in the art, and includes all technical equivalents that operate in a similar manner to achieve a similar purpose. It should also be understood that reference to one or more steps of the method does not preclude the presence of additional method steps or intermediate method steps between those explicitly identified steps. Similarly, some steps of the method may be performed in a different order than that described herein without departing from the scope of the disclosed technology. For clarity and brevity, not all possible combinations are listed, and such variations are generally obvious to one skilled in the art and are intended to fall within the scope of the following claims.

Claims

1. A catheter, comprising: Proximal end, distal end, and longitudinal axis; Lining; A braided thread support structure is provided around the inner lining; A metal tubular reinforcement layer is disposed around the braided support structure, the metal tubular reinforcement layer extends from the proximal end to the middle of the catheter and includes one or more axial segments, the one or more axial segments being configured to impart different stiffness characteristics to at least a portion of the catheter; and Multiple outer polymer sheaths are disposed around the metal tubular reinforcing layer, and the multiple outer polymer sheaths bond the metal tubular reinforcing layer to the braided wire support structure; At least one of the one or more axial segments of the metal tubular reinforcing layer includes one or more strip-cut segments configured as a continuous longitudinally extending helix around the longitudinal axis; and At least one other axial segment of the one or more axial segments of the metal tubular reinforcing layer includes one or more axial hole patterns cut from the metal tubular reinforcing layer; A transition feature is located between the nearest strip-cut section and the farthest axial section of one or more axial sections comprising one or more axial hole patterns, the one or more axial hole patterns being a first axial hole pattern, the strip-cut section comprising a strip cut, and the transition feature further comprising one or more transition holes of a second axial hole pattern located between the strip cuts.

2. The catheter according to claim 1, further comprising a soft polymer end extending distally from the end of the braided support structure.

3. The conduit of claim 1, wherein the braided wire support structure comprises a stainless steel wire with a diameter of 0.0015 inches.

4. The catheter of claim 1, wherein the braided support structure includes a first PIC count in the proximal portion of the braided support structure, which is less than a second PIC count in the more distal portion of the braided support structure.

5. The catheter according to claim 4, wherein the first PIC count is in the range of 20 to 70.

6. The catheter according to claim 4, wherein the second PIC count is in the range of 120 to 200.

7. The conduit according to claim 1, wherein the metal tubular reinforcing layer is cut from a single continuous thiopanthus tube.

8. The conduit according to claim 1, wherein at least one of the one or more axial hole patterns comprises a gradient of varying pore density.

9. The conduit according to claim 1, wherein at least one of the one or more axial hole patterns comprises holes of different diameters.

10. The conduit according to claim 1, wherein at least one of the one or more axial hole patterns comprises a helical pattern around the longitudinal axis.

11. The conduit of claim 10, wherein the helical pattern includes an axial portion having a first pitch, the first pitch being different from a second pitch of another axial portion of the helical pattern; and The spiral pattern includes an axial portion having a first helix angle, which is different from a second helix angle of another axial portion of the spiral pattern.

12. The catheter of claim 1, wherein at least one of the one or more strip cutting segments includes an axial portion having a first strip width, the first strip width being different from a second strip width of another axial portion of the same strip cutting segment.

13. The catheter of claim 1, wherein at least one of the one or more strip cutting segments includes an axial portion having a first pitch, the first pitch being different from a second pitch of another axial portion of the same strip cutting segment.

14. The catheter of claim 1, wherein at least one of the one or more strip cutting segments includes an axial portion having a first helix angle, the first helix angle being different from a second helix angle of another axial portion of the same strip cutting segment.

15. The conduit of claim 1, wherein the transition feature is configured to integrate a longitudinal stiffness transition between one or more axial segments of the metallic tubular reinforcing layer.

16. A catheter for vascular access, the catheter comprising: Proximal end, distal end, and longitudinal axis; A braided support structure is provided around the liner and extends from the proximal end of the catheter to a point near the distal end; A metal tubular reinforcing layer is disposed around the braided wire support structure. The metal tubular reinforcing layer extends from the proximal end to the middle of the conduit and includes a portion having one or more axial hole patterns and a portion having one or more strip-cut sections. The one or more axial hole patterns are cut from the metal tubular reinforcing layer and have a gradient of varying hole density. The one or more strip-cut sections are configured as a continuous longitudinally extending spiral around the longitudinal axis. A transition feature, the transition feature being between the nearest side of one or more strip-cut sections and the farthest end of a portion including one or more axial hole patterns, the one or more axial hole patterns being a first axial hole pattern, the strip-cut section including a strip cut, the transition feature also including one or more transition holes of a second axial hole pattern located between the strip cuts; and One or more outer polymer sheaths are disposed around the metal tubular reinforcing layer, and at least one of the one or more outer polymer sheaths includes a durometer hardness that is different from that of an adjacent polymer sheath.

17. The conduit of claim 16, wherein the transition feature is configured to reduce stress and integrate a longitudinal stiffness transition between one or more axial segments of the metallic tubular reinforcement layer.

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