Medical Device Having Tubular Reinforcement

Abstract

The catheter 10 includes a tubular structure 200 having a first ring element 210a, a second ring element 210b, and a third ring element 210c, the tubular structure comprising a set of first connecting members 220a between the first and second ring elements, the tubular structure comprising a set of second connecting members 220b between the second and third ring elements, the second ring element comprising a first ring portion 222a and a second ring portion 222b, each of the first and second ring portions extending in a direction that is not perpendicular to the longitudinal axis of the tubular structure, and the first ring portion and the second ring portion together forming a non-planar configuration of the second ring element.

Description

[Technical Field]

[0001] The present disclosure relates generally to minimally invasive medical devices, and more particularly to catheters. [Background technology]

[0002] The use of intravascular catheters to access and treat various types of conditions, including vascular abnormalities, is well known. For example, an appropriate intravascular catheter can be inserted into a patient's vascular system. A commonly used intravascular application to access a patient's target site involves inserting a guidewire (e.g., a coronary artery guidewire, a peripheral guidewire, a neurovascular guidewire, etc.) through an incision in the femoral artery near the groin, and advancing a guide catheter and an introducer / diagnostic catheter over the wire, with the guidewire leading the way, until the guide catheter is positioned in the common or internal carotid artery. The introducer and / or diagnostic catheter is then removed, and a neurovascular catheter is advanced through the guide catheter, typically over the guidewire (often in conjunction with a microcatheter or delivery-assist catheter), to position the neurovascular catheter at the target site. Simultaneously with or after the distal end of the neurovascular catheter is positioned at the target site, all devices within the neurovascular catheter's lumen are removed, and treatments, such as medication infusion, implant delivery, or aspiration through the neurovascular catheter, are performed via the neurovascular catheter's lumen.

[0003] To ensure trackability, flexibility of the distal segment of the catheter is crucial. Currently, catheters are equipped with a solid marker band made of a radiopaque material at the distal end, which allows imaging of the catheter. The solid marker band is a solid ring attached to the distal end of the hypotube. The solid ring increases catheter stiffness, making it difficult to track or deviate from branch arteries, such as the ophthalmic artery. Therefore, a new marker device that can reduce catheter stiffness is desirable.

[0004] Additionally, certain applications, such as neurovascular interventions, require catheters to navigate tortuous and complex vasculature. By using appropriately sized devices with the required performance characteristics, including pushability, trackability, and, most importantly, distal tip flexibility, virtually any target site within the vasculature can be accessed, including tortuous cerebral, peripheral, and venous vessels. Furthermore, the force applied at the proximal end of these catheters must be transmitted to the distal end to ensure adequate pushability (axial stiffness) and torque transmission (rotational force). Balancing these characteristics is highly desirable but challenging.

[0005] Additionally, a catheter can have a lumen with a certain cross-sectional shape. During use, a catheter may be bent. For example, the catheter may be bent by manipulating a pull wire and / or by bending the catheter over a guidewire or due to curvature of the anatomy. Bending the catheter places compression on one side of the catheter and tension on the other side of the catheter. In some cases, the compression caused by bending the catheter can cause the catheter to kink, thereby collapsing the catheter lumen. Designing a catheter that resists such kinking while achieving certain bending flexibility and torsional stiffness is very challenging. Summary of the Invention

[0006] The catheter includes a tubular structure having a first ring element, a second ring element, and a third ring element, the tubular structure including a first set of connecting members between the first ring element and the second ring element, the tubular structure including a second set of connecting members between the second ring element and the third ring element, the second ring element including a first ring portion and a second ring portion, each of the first and second ring portions extending in a direction that is not perpendicular to a longitudinal axis of the tubular structure, and the first ring portion and the second ring portion together forming a non-planar configuration of the second ring element.

[0007] Optionally, the first ring portion and the second ring portion are different respective circumferential portions of the second ring element.

[0008] Optionally, the first ring portion has a first flat portion lying in a first plane, and the second ring portion has a second flat portion lying in a second plane different from the first plane, each of the first plane and the second plane forming an angle that is not perpendicular to the longitudinal axis of the catheter.

[0009] Optionally, the second ring element also includes a junction portion between the first and second ring portions, the junction portion including a central portion, a first portion, and a second portion, the first and second portions being on opposite sides of the central portion.

[0010] Optionally, the first and second portions of the interface portion are curved in opposite directions.

[0011] Optionally, a central portion of the interface is configured to rotate and / or resist moments when the catheter is under tension or when the catheter is bent.

[0012] Optionally, the first set of connecting members and the second set of connecting members are configured to move relative to the second ring element when the catheter is bent and / or when the catheter is subjected to an axial load.

[0013] Optionally, one of the first set of connecting members has a width and a thickness, the width being less than the thickness.

[0014] Optionally, the total number N of the first sets of connecting members satisfies the condition N≧F / (S×A), where F is the axial load on the catheter, S is the allowable axial stress on each of the first sets of connecting members, and A is the cross-sectional area of ​​one of the connecting members.

[0015] Optionally, a space between one of the first set of connecting members and the second ring element has a width L, and the width L of the space is such that L<(nπ 2 EI / F) 1 / 2 where n=4 or less, E is the elastic modulus of the material of the polymer structure spanning space, F is the axial load on the polymer structure, and I is the moment of inertia of the cross section of the polymer structure.

[0016] Optionally, a space between one of the first set of connecting members and the second ring element has a width L, and the catheter further comprises a polymer structure spanning the space, the polymer structure having a modulus of elasticity E and a ratio E / L 2 is F / (nπ 2 I) <E / L 2 where F is the axial load on the polymer structure, n=4 or less, and I is the cross-sectional moment of inertia of the polymer structure.

[0017] Optionally, the catheter further includes a marker element attached to or extending from the distal end of the tubular structure.

[0018] Optionally, the catheter further includes a polymer layer bonded to the tubular structure, the polymer layer extending distally beyond the distal tip of the marker element to form a polymer tip, the polymer tip extending less than 3 mm beyond the distal tip of the marker element.

[0019] Optionally, the catheter further comprises a first polymeric layer circumferentially disposed around the outer surface of the tubular structure.

[0020] Optionally, the first polymer layer has a modulus of at least 2 MPa and / or at most 7 MPa, a tensile elongation (strain) at yield of at least 300%, a tensile elongation (strain) at break of at least 500%, or any combination thereof.

[0021] Optionally, the catheter further comprises a second polymeric layer disposed on the interior surface of the tubular structure.

[0022] Optionally, the second polymer layer has a modulus of at least 2 MPa and / or at most 7 MPa, a tensile elongation (strain) at yield of at least 300%, a tensile elongation (strain) at break of at least 500%, or any combination thereof.

[0023] Optionally, the first polymer layer and the second polymer layer form a tube that covers the entire tubular structure, the material of the tube having a higher elastic modulus than the material of the tubular structure and being more elastic than the material of the tubular structure.

[0024] Optionally, the stiffness of the combination of the tubular structure and the tube is at least four times greater than the stiffness of the tubular structure alone.

[0025] Optionally, the tubular structure has a wall gap to kerf width ratio in the range of 1-5.

[0026] The catheter includes a tubular structure having a first ring element, a second ring element, and a third ring element, the tubular structure also including a first set of connecting members between the first ring element and the second ring element, the tubular structure also including a second set of connecting members between the second ring element and the third ring element, the second ring element including a first ring portion and a second ring portion, the first and second ring portions together forming a non-planar configuration of the second ring element.

[0027] Optionally, the first ring portion and the second ring portion have the same configuration.

[0028] Optionally, the first ring portion and the second ring portion are different respective circumferential portions of the second ring element.

[0029] Optionally, the first ring portion has a first flat portion lying in a first plane, and the second ring portion has a second flat portion lying in a second plane different from the first plane, each of the first plane and the second plane forming an angle that is not perpendicular to the longitudinal axis of the catheter.

[0030] Optionally, the second ring element also comprises an interface between the first and second ring portions.

[0031] Optionally, the interface portion includes a central portion, a first portion and a second portion, the first and second portions being on opposite sides of the central portion.

[0032] Optionally, the first and second portions of the interface portion are curved in opposite directions.

[0033] Optionally, a central portion of the interface is configured to rotate and / or resist moments when the catheter is under tension or when the catheter is bent.

[0034] Optionally, the first set of connecting members and the second set of connecting members are configured to move relative to the second ring element when the catheter is bent and / or when the catheter is subjected to an axial load.

[0035] Optionally, one of the first set of connecting members has a width and a thickness, the width being less than the thickness.

[0036] Optionally, the total number N of the first sets of connecting members satisfies the condition N≧F / (S×A), where F is the axial load on the catheter, S is the allowable axial stress on each of the first sets of connecting members, and A is the cross-sectional area of ​​one of the connecting members.

[0037] Optionally, a space between one of the first set of connecting members and the second ring element has a width L, and the width L of the space is such that L<(nπ 2 EI / F) 1 / 2 where n=4 or less, E is the elastic modulus of the material of the polymer structure spanning space, F is the axial load on the polymer structure, and I is the moment of inertia of the cross section of the polymer structure.

[0038] Optionally, a space between one of the first set of connecting members and the second ring element has a width L, and the catheter further comprises a polymer structure spanning the space, the polymer structure having a modulus of elasticity E and a ratio E / L 2 is F / (nπ 2 I) <E / L 2 where F is the axial load on the polymer structure, n=4 or less, and I is the cross-sectional moment of inertia of the polymer structure.

[0039] Optionally, the catheter further includes a marker element attached to or extending from the distal end of the tubular structure.

[0040] Optionally, the marker element comprises a ring structure having a distal end, a proximal end, and a body extending between the distal and proximal ends, the ring structure being made from a radiopaque material, the distal end of the ring structure including protruding elements circumferentially arranged about an axis of the ring structure, and the proximal end of the ring structure being configured to couple to or extend from a tubular structure.

[0041] Optionally, the protruding elements include respective curved tip surfaces, and the distal end of the ring structure further includes curved trough surfaces, each curved trough surface being disposed between two adjacent curved tip surfaces.

[0042] Optionally, the curved tip surface and the curved trough surface together form a sinusoidal profile extending circumferentially about the axis of the ring structure.

[0043] Optionally, the catheter further comprises a first polymeric layer circumferentially disposed around the outer surface of the tubular structure.

[0044] Optionally, the first polymer layer comprises a first segment and a second segment proximal to the first segment.

[0045] Optionally, the first segment is made from NEUSoft.

[0046] Optionally, the second segment is made from a different material than NEUSoft.

[0047] Optionally, the catheter further comprises a second polymeric layer disposed on the interior surface of the tubular structure.

[0048] Optionally, the second polymer layer comprises a first segment and a second segment proximal to the first segment, the first segment of the second polymer layer being made from NEUSoft.

[0049] Optionally, the second segment of the second polymer layer is made from a different material than NEUSoft.

[0050] Optionally, the first segment of the first polymer layer and the first segment of the second polymer layer are made from the same material.

[0051] Optionally, the catheter further includes a marker element having a ring structure and a plurality of holes circumferentially arranged in a body of the ring structure, and a portion of the first polymer layer extends into the holes in the ring structure.

[0052] Optionally, the first polymer layer extends distally beyond the distal tip of the marker element to form a polymer tip.

[0053] Optionally, the polymer tip extends less than 3 mm beyond the distal tip of the marker element.

[0054] Optionally, the first polymer layer has a modulus of at least 2 MPa and / or at most 7 MPa, a tensile elongation (strain) at yield of at least 300%, a tensile elongation (strain) at break of at least 500%, or any combination thereof.

[0055] Optionally, the second polymer layer has a modulus of at least 2 MPa and / or at most 7 MPa, a tensile elongation (strain) at yield of at least 300%, a tensile elongation (strain) at break of at least 500%, or any combination thereof.

[0056] Optionally, the first polymer layer and the second polymer layer form a tube that covers the entire tubular structure, the material of the tube having a higher elastic modulus than the material of the tubular structure and being more elastic than the material of the tubular structure.

[0057] Optionally, the stiffness of the combination of the tubular structure and the tube is at least four times greater than the stiffness of the tubular structure alone.

[0058] Optionally, the tubular structure has a wall gap to kerf width ratio in the range of 1-5.

[0059] Other and further aspects and features of the embodiments will become apparent from the following detailed description when considered in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0060] [Figure 1] FIG. 1 illustrates a catheter according to some embodiments. [Figure 2] FIG. 2A shows a distal segment of the catheter of FIG. 1, particularly showing the distal segment of the catheter having a marker device and a tubular structure. FIG. 2B shows the tubular structure of FIG. 2A. FIG. 2C shows an enlarged view of a joint in the tubular structure of FIG. 2A. FIG. 2D shows the expansion of the lumen of the tubular structure of FIG. 2A due to the auxetic angle of the ring elements within the tubular structure. FIG. 2E shows the tubular structure of FIG. 2A under tension. FIG. 2F shows the tubular structure of FIG. 2A bent. FIG. 2G shows an enlarged view of the tubular structure of FIG. 2C, particularly showing the gap width control bump. [Figure 3] FIG. 3 shows the marker device of FIG. 2A. [Figure 4] FIG. 4 shows a variation of the marker device of FIG. 3, particularly showing a marker device having multiple tabs. [Figure 5] FIG. 5 shows a variation of the marker device of FIG. 3, particularly showing a marker device having multiple tabs. [Figure 6] FIG. 6 illustrates a variation of the marker device of FIG. 4, particularly illustrating a marker device having multiple openings. [Figure 7] FIG. 7 shows the distal segment of the catheter of FIG. [Figure 8] FIG. 8 shows an example of the catheter of FIG. 1, specifically showing a catheter having a first layer on the outside of the tubular structure and a second layer on the inside of the tubular structure. [Figure 9] 9A and 9B show another tubular structure that differs from the tubular structure of FIG. 2B. DETAILED DESCRIPTION OF THE INVENTION

[0061] Various embodiments will now be described with reference to the drawings. Note that elements of similar structure or function are represented by the same reference numerals throughout the drawings. Also, note that the drawings are intended only to facilitate the description of the embodiments. They are not intended as an exhaustive description of the invention or as limiting the scope of the invention. Furthermore, the illustrated embodiments do not necessarily have all the aspects or advantages shown. An aspect or advantage discussed in connection with a particular embodiment is not necessarily limited to that embodiment and may be implemented in any other embodiment, even if not so illustrated or explicitly described.

[0062] For the following defined terms, these definitions shall be applied unless a different definition is given in the claims or elsewhere in this specification.

[0063] In this specification, all numerical values ​​are intended to be modified by the term "about," whether explicitly stated or not. The term "about" generally refers to a range of numerical values ​​that one of ordinary skill in the art would consider equivalent to the stated value (i.e., having the same function or result). In many cases, the term "about" includes numerical values ​​rounded to the nearest significant figure. In some cases, the term "about" may refer to a range of values ​​within ±10% of a value. For example, a value of 2 or a value of about 2 may refer to any value within the range of 2 ±10% (= 2 ± 0.2 = 1.8 to 2.2).

[0064] When numerical ranges are recited by endpoints, all numbers within that range are included (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0065] As used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. As used herein and in the appended claims, the term "or" is generally used in its sense including "and / or" unless the content clearly dictates otherwise.

[0066] 1 illustrates a catheter 10 according to some embodiments. The catheter 10 includes a tube 11 having a distal end 12, a proximal end 14, and a tube body 16 extending between the distal end 12 and the proximal end 14. The catheter 10 also includes a handle 18 attached to the proximal end 14 of the tube 11.

[0067] The tube 11 includes an outer surface 21, an inner surface 22, and a lumen 30 defined by the inner surface. The tube 11 also includes a tubular structure 200 configured to provide a certain rigidity to the tube 11. As shown, the tubular structure 200 is disposed between the outer surface 21 and the inner surface 22 of the tube 11, thereby embedding the tubular structure 200 within the wall of the tube 11. In other embodiments, the tubular structure 200 may be located on the outer surface 21 or the inner surface 22 of the tube 11. The tubular structure 200 has a distal end, a proximal end, and a body extending between the distal and proximal ends. The tubular structure 200 / catheter 10 also has a longitudinal axis 20 defined by the distal and proximal ends of the tubular structure 200.

[0068] In the illustrated embodiment, the lumen 30 of the catheter 10 has a cross-sectional shape when the catheter 10 is in a relaxed state. The tubular structure 200 is configured to maintain the cross-sectional shape of the lumen 30 as the catheter 10 bends, so as to prevent the catheter 10 from kinking. Optionally, the tubular structure 200 can also be configured to provide axial stiffness, bending stiffness, torsional stiffness, or any combination thereof, to the catheter 10.

[0069] tubular structure 2A shows a distal segment of the catheter 10 of FIG. 1, and in particular shows the distal segment of the catheter 10 having a marker element (marker device) 240 and a tubular structure 200. The tubular structure 200 is configured to provide axial stiffness, bending stiffness, torsional stiffness, or any combination thereof, to the catheter 10. In some cases, the tubular structure 200 can include a hypotube.

[0070] The distal segment of the catheter 10 also includes a polymer layer 260 circumferentially disposed around the marker element 240 and / or the tubular structure 200. The distal segment of the catheter 10 further includes a polymer tip 270. The polymer tip 270 includes a polymer tube 272 having a distal tip 280. The polymer tip 270 is distal to the marker element 240 and / or the tubular structure 200. In some cases, the polymer tip 270 may be integral with the polymer layer 260. For example, the polymer tip 270 may be formed with at least a portion of the polymer layer 260 using the same material. In other cases, the polymer tip 270 and the polymer layer 260 may be formed separately and then connected together using, for example, adhesives, fusion techniques, etc. In such cases, the polymer tip 270 and the polymer layer 260 may be made from the same material or from different respective materials.

[0071] The distal segment of the catheter 10 can also include a polymer layer 262 (shown in FIG. 8) disposed on the inner surface of the marker element 240 and / or the inner surface of the tubular structure 200. In some cases, the polymer tip 270 may be integral with the polymer layer 262. For example, the polymer tip 270 may be formed along with at least a portion of the polymer layer 262 using the same material. In other cases, the polymer tip 270 and the polymer layer 262 may be formed separately and then connected together using, for example, adhesives, fusion techniques, or the like. In such cases, the polymer tip 270 and the polymer layer 262 may be made from the same material or from different respective materials. The polymer layers 260, 262 are further described with reference to FIGS. 8 and 9.

[0072] Figure 2B shows the tubular structure 200 of Figure 2A. The tubular structure 200 is configured to provide axial stiffness, bending stiffness, torsional stiffness, or any combination thereof, to the catheter 10.

[0073] The tubular structure 200 has a plurality of ring elements 210 arranged in series along the longitudinal axis 20. In the illustrated embodiment, the ring elements 210 are respective closed loops. Three of the ring elements 210 (e.g., first ring element 210a, second ring element 210b, and third ring element 210c) are identified in the drawing. The tubular structure 200 can include any number of ring elements 210. As shown, each ring element 210 has a plurality of ring segments 222 and a plurality of junction segments 224. Each junction segment 224 is between two adjacent ring segments 222. The ring segments 222 and junction segments 224 are circumferentially connected to form the ring element 210.

[0074] Each ring segment 222 of ring element 210 is a partial ring, with a portion of each ring segment 222 having a straight profile when viewed from the side, as shown in FIG. 2B . The straight (or flat) portion of ring segment 222 lies in a plane that forms an acute angle 286 with longitudinal axis 20 (e.g., when viewed from the side of the tubular structure as shown). The acute angle is anywhere between 60 degrees and 89 degrees, and more preferably, anywhere between 75 degrees and 86 degrees. In one embodiment, the acute angle may be 84 degrees ± 2 degrees. In other embodiments, ring portion 222 may not include a flat portion. For example, in other cases, the entire ring segment 222 may have a curved profile when viewed from the side of tubular structure 200.

[0075] As shown, each of the first and second ring portions 222a, 222b of the ring element 210b extends in a direction that is not perpendicular to the longitudinal axis of the tubular structure, thereby giving the ring element 210b a non-planar configuration. The ring element 210 is considered to have a “non-planar configuration” if the different circumferential portions of the ring element 210 collectively form a surface that is not a straight surface. That is, even if the ring element 210 were relatively “flat” and the entire ring element 210 were contained within a thin cylinder, the ring element 210 would still be considered to have a non-planar configuration if the different circumferential portions of the ring element 210 did not collectively form a straight surface. This non-planar configuration of the ring elements 210 is advantageous because it allows the connecting members 220 between the ring elements 210 to be densely positioned adjacent to each other and in close proximity to adjacent ring elements 210. As shown, the majority of each connecting member 220 forms a uniform spacing with a portion of a first adjacent ring element 210 and also with a portion of a second adjacent ring element 210 (the first and second adjacent ring elements 210 being on opposite sides of the connecting member 220). When the tubular structure 200 is coated or encapsulated with one or more polymer layers to form a polymer tube attached to the tubular structure 200, the uniform spacing results in a uniform width of polymer material in the polymer tube within the spacing. As a result, the polymer tube attached to the tubular structure 200 has uniform mechanical properties throughout the ring element 210 and / or does not experience significant stress concentrations throughout the ring element during use. The connecting members 220 and polymer tubes are described in further detail below.

[0076] In other embodiments, a non-planar configuration is not required for each ring element 210; instead, each ring element 210 may have a planar configuration in which the entire ring element 210 lies within a plane.

[0077] In the illustrated example, each ring element 210 has a plurality of circumferentially arranged ring segments 222, each of which is a circumferential portion of the ring element 210. Within the ring element 210, the ring segments 222 have the same configuration (e.g., the same dimensions, shape, profile, etc.), such that the configuration of the ring segments 222 within the ring element 210 is repeated circumferentially. The ring segments 222 within each ring element 210 are not coplanar. In cases where each ring segment 222 has a flat (straight) portion, the flat portions of each ring segment 222 within the ring element 210 lie in different respective planes (e.g., the planes may form an acute angle with respect to each other). In other cases where each ring segment 222 has a non-flat profile (e.g., a curved profile, a zigzag profile, etc.), the non-flat profile of each ring segment 222 is repeated circumferentially around the ring element 210. Because the ring portions 222 of each ring element 210 have the same non-flat profile, corresponding portions of the ring portions 222 are at the same longitudinal position relative to the longitudinal axis 20, but different portions of the ring portions 222 have different respective longitudinal positions relative to the longitudinal axis 20.

[0078] In some cases, each ring element 210 has only two ring portions 222. In such cases, the first ring portion extends over at least 40% (e.g., 50%) of the circumference of the ring element 210, and the second ring portion 222 also extends over at least 40% of the circumference of the second ring element 210. In other cases, each ring element 210 can have three or more ring portions 222. For example, each ring element 210 can have three ring portions 222. In such cases, the first, second, and third ring portions 222 can each extend over at least 30% (e.g., 33%) of the circumference of the ring element 210. In still other cases, each ring element 210 can have four ring portions 222. In such cases, each ring portion 222 can each extend over at least 22% (e.g., 25%) of the circumference of the ring element 210. In a further embodiment, each ring element 210 can have five ring segments 222. In such a case, each ring segment 222 can extend over at least 18% (e.g., 20%) of the circumference of the ring element 210.

[0079] Each interface 224 of ring element 210 connects between two adjacent ring portions 222 of ring element 210. Interface 224 forms a "step" between two adjacent ring portions 222. This allows ring portions 222a, 222b of ring element 210b to be connected to each other even if ring portions 222a, 222b do not lie entirely in a common plane.

[0080] In the illustrated example, each ring element 210 has two interfaces 224. In other examples, each ring element 210 can have three or more interfaces 224 (e.g., 3, 4, 5, 6, 7, 8, etc. interfaces 224).

[0081] As shown in FIGS. 2B and 2C , the junction portion 224 of the ring element 210 has, in a side view, a central portion 225, a first curved portion 226, and a second curved portion 227. In some cases, the central portion 225 of the junction portion 224 is configured to rotate and / or resist moments when the catheter 10 is under tension or bent. The first curved portion 226 and the second curved portion 227 are on opposite sides of the central portion 225. The first curved portion 226 and the second curved portion 227 are connected to respective ring portions 222 on opposite sides of the central portion 225. As shown, the first curved portion 226 and the second curved portion 227 are curved by the same amount, but the first curved portion 226 and the second curved portion 227 are curved in different directions (e.g., in opposite directions). In other cases, the amount of curvature of first curved portion 226 may be different from the amount of curvature of second curved portion 227. Also, in other cases, first portion 226 and second portion 227 may each have a linear shape rather than a curved shape. For example, in other cases, first portion 226, second portion 227, and central portion 225 may each have a linear shape and form a zigzag shape (e.g., when viewed from the side).

[0082] Moreover, in other cases, portions 226, 227 may be considered part of the respective ring portions 222 in ring element 210. In such cases, interface portion 224 includes central portion 225 but does not include portions 226, 227.

[0083] The tubular structure 200 also includes connecting members 220 connected between adjacent ring elements 210. During use, the ring elements 210 provide structural rigidity to maintain the shape of the central lumen of the tubular structure 200 while the catheter 10 is bent. At the same time, the connecting members 220 maintain the structural integrity of the tubular structure 200 by allowing the spacing between adjacent ring elements 210 to change predictably as the catheter 10 is bent. The connecting members 220 also impart bending stiffness, axial stiffness, torsional stiffness, or any combination thereof, to the tubular structure 200. As such, the ring elements 210 and the connecting members 220 are two distinct groups of structural components of the tubular structure 200 that behave differently during use.

[0084] As shown in FIG. 2B , the tubular structure 200 includes a set of first connecting members 220a connected between a first ring element 210a and a second ring element 210b. The tubular structure 200 also includes a set of second connecting members 220b connected between a second ring element 210b and a third ring element 210c. Each connecting member 220a / 220b includes a first member end 232, a second member end 234 opposite the first member end 232, and a member body 236 extending between the first member end 232 and the second member end 234. The member body 236 can form an angle with respect to the adjacent ring element 210 connected to the member body 236. In the illustrated example, when the tubular structure 200 is in the relaxed configuration, the angle formed between the member body 236 and the ring element 210 (e.g., the ring portion 222 of the ring element 210) is 0 degrees. This means that when tubular structure 200 is in a relaxed configuration, member body 236 of connecting member 220 is parallel to a portion of ring element 210 (e.g., ring portion 222). In other cases, the angle may be an acute angle greater than 0 degrees and less than 90 degrees. In some cases, the angle may be measured with tubular structure 200 "deployed" in a flat configuration.

[0085] In some cases, the tubular structure 200 may have a total of two connecting members 220 between each adjacent pair of ring elements 210. In other examples, the tubular structure 200 may have three or more (e.g., 3, 4, 5, 6, 7, 8, etc.) connecting members 220 between each adjacent pair of ring elements 210.

[0086] Additionally, the first member end 232 of each connecting member 220 and the second member end 234 of each connecting member 220 can define a line that is not parallel to the longitudinal axis 20 (e.g., when viewed from the side of the tubular structure 200). As shown in FIG. 2B , the member body 236 of the connecting member 220 forms an angle 288 with respect to the longitudinal axis 20. The angle 288 can be any angle greater than 0 degrees and less than 90 degrees. As a non-limiting example, the angle 288 can be greater than 70 degrees, greater than 80 degrees, greater than 85 degrees, etc.

[0087] In the illustrated example, member body 236 is the major portion of each connecting member 220. Also, member ends 232 / 234 of connecting member 220 are the minor portions that connect to ring element 210. In some cases, member body 236 can comprise at least 70%, or at least 80%, or at least 90%, or at least 95% of the overall length of connecting member 220. In such cases, member ends 232 / 234 can comprise the remaining percentage of the length of connecting member 220. Member ends 232 / 234 are illustrated as having a curved shape. In other cases, member ends 232 / 234 can have a straight shape.

[0088] In some cases, the member body 236 may comprise 100% of the overall length of the connecting member 220. In such cases, the member ends 232 / 234 terminate at the ends of the member body 236 and have no dimensions.

[0089] 2C illustrates a junction 229 where two connecting members 220 are connected to a ring element 210. As shown, the junction 229 is formed by an end 234 of a connecting member 220, an end 232 of another connecting member 232, a central portion 225 of an interface 224 of a ring element 210, a first portion 226 of an interface 224 of a ring element 210, and a second portion 227 of an interface 224 of a ring element 210.

[0090] Also, as shown in FIG. 2C , each ring element 210 is tilted with respect to the longitudinal axis 20, forming an “auxetic angle” with respect to a plane perpendicular to the longitudinal axis 20. The auxetic angle is advantageous because it allows the ring elements 210 to maintain, or even “enlarge,” their central lumen while the tubular structure 200 is bent and / or under tension. During use of the catheter 10, in response to bending or tension applied to the tubular structure 200, the ring elements 210 of the tubular structure 200 can rotate about an axis perpendicular to the longitudinal axis 20. As a result, as shown in FIG. 2D , the ring elements 210 can move from a first position P1, where the ring elements 210 are at an oblique angle with respect to the longitudinal axis 20 (or auxetic angle A with respect to a plane perpendicular to the longitudinal axis 20), to a second position P2, where the ring elements 210 are perpendicular to the longitudinal axis 20. This “enlarges” the central lumen of the tubular structure 200. Note that connecting member 220 is not shown in FIG. 2D for clarity. As shown, when ring element 210 is in first position P1, the lumen of tubular structure 200 has a first width W1. However, when tubular structure 200 is stressed, ring element 210 moves from first position P1 to second position P2, resulting in the lumen expanding from first width W1 to second width W2. Thus, the auxetic angle of ring element 210 effectively provides tubular structure 200 with a positive Poisson's ratio, in the sense that when tubular structure 200 is under tension, the cross-sectional dimension of tubular structure 200 increases. In other words, when tubular structure 200 is under tension in a direction parallel to longitudinal axis 20, the lateral dimension of tubular structure 200 increases (because ring element 210 is rotated from an oblique orientation to an orientation in which ring element 210 is perpendicular to longitudinal axis 20). This is opposite to the behavior of many materials that have a negative Poisson's ratio, defined as the negative ratio of lateral strain to axial strain: when tension is applied to a material, it stretches in the direction of the tension and also decreases in its lateral dimension (perpendicular to the direction of the tension).

[0091] In some cases, the number N of connecting members 220 between two ring elements 210 can be determined based on (1) the axial load demand F (the maximum expected axial force, such as compression or tension) on the catheter 10, (2) the cross-sectional area A of each connecting member 220, (3) the allowable axial stress S of each connecting member 220, or (4) any combination thereof. In one embodiment, N≧F / (S×A). Additionally, the cross-sectional area A of the connecting member 220 can be calculated by multiplying the thickness t of the connecting member 220 by the width w of the connecting member 220 when the connecting member 220 has a rectangular cross-section, or when the cross-section is not rectangular but can be approximated as a rectangle. In some cases, the thickness t of the connecting member 220 can be the wall thickness of the tubular structure 200 or a dimension measured radially at the cross-section of the connecting member 220. In some cases, the width w of the connecting member 220 can be a dimension measured tangentially or circumferentially at the cross-section of the connecting member 220. By way of non-limiting example, the axial load requirement F of catheter 10 can be 2 Newtons or greater, 3 Newtons or greater, 4 Newtons or greater, 5 Newtons or greater, etc.

[0092] Furthermore, to ensure that each connecting member 220 moves relative to the adjacent ring element 210 in a tangential direction (i.e., a direction perpendicular to the radial direction in the cross section of the tubular structure 200) rather than in a radial direction in the cross section of the tubular structure 200, the thickness t of the connecting member 220 is designed to be greater than the width w of the connecting member 220 (t>w).

[0093] In some cases, segmentation techniques can be used in the design of connecting member 220 to ensure that the condition t>w is met for each connecting member 220. For example, if the width w of the initial design of connecting member 220 is greater than its thickness t, the initial design of the connecting member can be "segmented" into two halves such that the width w of the initial design is reduced by 50%. In other cases, segmentation can be performed to divide the connecting member into more than two parts (e.g., three parts, four parts, etc.) such that the condition t>w is met for each connecting member 220.

[0094] In some cases, the tubular structure 200 is designed such that t > w and N x t x w x S > F for each connecting member 220. Some design approaches can consider these two requirements together. For example, for a given number N of connecting members 220, t and w can be determined using the two equations above. Alternatively, for a given t and a given w, the minimum number N of connecting members 220 can be determined.

[0095] FIG. 2E illustrates the tubular structure 200 in tension. The tubular structure 200 in FIG. 2E is the same as segment A of the tubular structure 200 in FIG. 2A, except that the tubular structure 200 in FIG. 2E has three connecting members 220 (rather than two connecting members 220) between two adjacent ring elements 210. As shown, the member body 236 of each connecting member 220 rotates and / or bends relative to the adjacent ring element 210 when the tubular structure 200 is axially loaded (e.g., in tension). Thus, the angle 288 changes as the tubular structure 200 is axially loaded. Furthermore, even as the spacing between adjacent ring elements 210 changes (e.g., increases or decreases) when the tubular structure 200 is axially loaded, the cross-sectional shape of the ring elements 210 is maintained, and the angle between the ring elements 210 and the longitudinal axis 20 is also maintained.

[0096] FIG. 2F illustrates the tubular structure 200 being bent. The tubular structure 200 in FIG. 2E is the same as segment A of the tubular structure 200 in FIG. 2A, except that it has three connecting members 220 (rather than two connecting members 220) between two adjacent ring elements 210. As shown, when the tubular structure 200 is bent, the angle between the ring elements 210 and the longitudinal axis 20 remains substantially the same (e.g., the angle does not change by more than 10% compared to when the tubular structure 200 is not bent). The connecting members 220 are configured to move relative to the ring elements 210 in response to bending of the tubular structure 200. This allows the connecting members 220 to adapt to changes in the spacing distance between adjacent ring elements 210 due to bending of the tubular structure 200.

[0097] The tubular structure 200 is advantageous because the closed-loop ring elements 210 prevent radially inward collapse of the tubular structure 200. Thus, the cross-sectional shape of the ring elements 210 is maintained while the tubular structure 200 is being bent, preventing kinking of the catheter 10.

[0098] As shown in FIG. 2C , the tubular structure 200 also includes gap width control bumps 238. Each gap width control bump 238 is disposed along a side of the ring element 210 and is configured to prevent the gap width between the ring element 210 and the adjacent connecting member 220 from exceeding a predetermined gap limit. The gap width control bumps 238 are shown in the enlarged view of FIG. 2G . As shown, a predetermined gap width limit 239a of the tubular structure 200 is indicated. Without the gap width control bumps 238, the side of the ring element 210 would have a dashed outline, and the gap width 239b between that portion of the ring element 210 and the adjacent connecting member 220 would exceed the predetermined gap width limit 239a. The introduction of the gap width control bumps 238 reduces the gap width 239b to a gap width 239c that is equal to or less than the predetermined gap width limit 239a. The gap width control bumps 238 are advantageous because they prevent gaps between elements of the tubular structure 200 from exceeding a threshold, thereby controlling the size of the polymer contained between the elements of the tubular structure 200. This can reduce the risk of structural failure at the interface between the polymer and the elements of the tubular structure 200. In other embodiments, the gap width control bumps 238 can be provided along the side of each connecting member 220 rather than along the side of the ring element 210. In further embodiments, the gap width control bumps 238 can be provided along the side of each connecting member 220 and along the side of each ring element 210.

[0099] 9A and 9B illustrate the bending of another tubular structure 900, different from the tubular structure 200 of FIG. 2A. The tubular structure 900 includes members 420 arranged in a cross shape. Unlike the tubular structure 200, the tubular structure 900 does not have closed-loop ring elements located in each plane. As shown in FIG. 9B, bending the tubular structure 900 can cause the tubular structure 900 to "collapse" because one side of the tubular structure 900 is compressed by the bending. As a result, if the tubular structure 900 defines a lumen with a circular cross-section in the relaxed state, the "collapsed" tubular structure 900 can result in the lumen having an elliptical shape 430. A catheter constructed using the tubular structure 900 can easily kink during use.

[0100] As described above, the connecting members 220 on either side of the ring elements 210 (i.e., the first set of connecting members 220 and the second set of connecting members 220) are configured to move relative to the ring elements 210 while the catheter 10 is bent and / or under an axial load. In some cases, when the tubular structure 200 is under tension, the angle between each ring element 210 and the longitudinal axis 20 remains substantially the same (e.g., the angle does not change by more than 10% compared to when the tubular structure 200 is not under tension). The connecting members 220 between adjacent pairs of ring elements 210 elastically flex in response to axial movement of the ring elements 210 when the tubular structure 200 is under tension. Additionally, the member body 236 of each connecting member 220 rotates and / or bends relative to the adjacent ring element 210 such that the angle 288 changes as the tubular structure 200 is under tension. Furthermore, the cross-sectional shape of the ring elements 210 is maintained when the tubular structure 200 is placed under tension and the spacing between adjacent ring elements 210 changes.

[0101] Also, in some cases, the tubular structure 200 can be bent very tightly, forming a curved shape with a small radius of curvature. Throughout the entire length of the bend, the gap between each pair of adjacent ring elements 210 remains substantially uniform (e.g., the gap between different pairs of adjacent ring elements 210 does not vary by more than 30%, more preferably by more than 20%, and more preferably by more than 10%). This applies to both the gap on the tension side and the gap on the compression side of the tubular structure 200. In other cases, the gap between different pairs of adjacent ring elements 210 may vary by more than 30% during bending of the catheter 10.

[0102] In some cases, the gap between each pair of adjacent ring elements 210 remains substantially uniform (e.g., the gap between different pairs of adjacent ring elements 210 does not change by more than 30%, more preferably does not change by more than 20%, or more preferably does not change by more than 10%) while the catheter 10 is under tension. In other cases, the gap between different pairs of adjacent ring elements 210 may change by more than 30% while the catheter 10 is under tension.

[0103] Additionally, in some cases, the tubular structure 200 can accommodate a 360-degree bend and form a curved shape with a small radius of curvature. Throughout the entire length of the bend, the gap between each pair of adjacent ring elements 210 remains substantially uniform (e.g., the gap between different pairs of adjacent ring elements 210 does not change by more than 30%, more preferably by more than 20%, and more preferably by more than 10%). This applies to both the tension-side and compression-side gaps of the bent tubular structure 200. In some cases, even when subjected to such extreme bending, the tubular structure 200 does not kink, and the structural integrity of the tubular structure 200 is maintained. In other cases, the gap between different pairs of adjacent ring elements 210 may change by more than 30% during the 360-degree bend of the tubular structure 200.

[0104] As shown in FIG. 2A, the tubular structure 200 includes multiple longitudinally aligned segments A-C. The segments A-C have different respective cut patterns, which impart different respective stiffness (or flexibility) to the segments A-C. In some cases, each of the segments can be constructed using tube segments having cutouts, and the tube segments can be joined together along the longitudinal axis. In other cases, two or more segments of the tubular structure 200 can be constructed using tube segments. In further cases, all of the segments that make up the entire tubular structure 200 can be implemented using a single tube segment.

[0105] In some cases, a first segment of tubular structure 200 is more flexible (e.g., more flexible bendingly, axially, torsionally, or any combination thereof) than a second segment of tubular structure 200, the second segment being more proximal than the first segment. In some cases, the second segment is more flexible than a third segment of tubular structure 200, the third segment being more proximal than the second segment. In some cases, the bending stiffness of tubular structure 200 decreases from the proximal end of tubular structure 200 to the distal end of tubular structure 200.

[0106] 2A , segments A-C have the same configuration (e.g., they all have ring elements 210 with ring portions 222 and junction portions 224, and connecting members 220) except for the different numbers of junction portions 224 and connecting members 220 between adjacent ring elements 210. In particular, in segment A of tubular structure 200, each ring element 210 has a total of two junction portions 224 and two ring portions 222, with two junction portions 224 connected to two respective connecting members 220. In segment B of tubular structure 200, each ring element 210 has a total of three junction portions 224 and three ring portions 222, with three junction portions 224 connected to three respective connecting members 220. In segment C of tubular structure 200, each ring element 210 has a total of four interface portions 224 and four ring portions 222, with the four interface portions 224 coupled to four respective connecting members 220. Increasing the number of connecting members 220 between adjacent ring elements 210 increases the stiffness of the segment of tubular structure 200, so that the above configuration results in tubular structure 200 having a first segment (segment A) that is the most flexible, a second segment (segment B—proximal to the first segment) that is stiffer than the first segment, and a third segment (segment C—proximal to the second segment) that is stiffer than the second segment.

[0107] It should be noted that tubular structure 200 is not limited to having all of segments A through C. In other cases, tubular structure 200 may have fewer than three segments (e.g., one segment or two segments) or more than three segments (e.g., four, five, six, seven, eight, nine, or ten segments). Also, in other cases, tubular structure 200 may have segment A with the configuration shown, but may also have segments B and C with configurations different from the configuration shown.

[0108] As shown in FIG. 2B , the tubular structure 200 includes a space 216 defined between the ring element 210 and the connecting member 220. In some embodiments, a filler material can be disposed in the space 216 defined between the ring element 210 and the connecting member 220. The filler material provides a seal that prevents fluid from passing through the wall of the tubular structure 200. The filler material can be a material extending from the outer polymer layer 260, a material extending from the inner polymer layer 262, a material separate from the polymer layers 260, 262, or any combination thereof. In the illustrated example, the connecting member 220 is parallel to the ring portion 222 of the ring element 210, so that the space 216 therebetween has a uniform width. This allows the filler material to have the same uniform (constant) corresponding width as it fills the space 216. This feature is advantageous because it reduces or prevents stress concentrations in the filler material, reduces the risk of the filler material breaking during use, reduces the risk of the filler material separating from the tubular structure 200, and allows the filler material to bond with and function better with the components of the tubular structure 200.

[0109] It should be noted that tubular structure 200 may be any member having a tubular configuration and is not limited to the example configurations shown in Figures 2A-2E. For example, in other cases, ring elements 210 and / or connecting members 220 may have different lengths, widths, and thicknesses to adjust the flexibility and kink resistance of tubular structure 200.

[0110] In any of the embodiments of the tubular structure 200 described herein, the tubular structure 200 can be fabricated from a raw tube. The raw tube can be a metal tube, an alloy tube, a plastic tube, a polymer tube, or a tube made from any other material. The raw tube is then cut to form the ring elements 210 and the connecting members 220. In such cases, the ring elements 210 and the connecting members 220 are part of the cut tube. Cutting the raw tube can, in some embodiments, be performed using laser cutting. For example, an electronic file can be created that stores geometric information (e.g., shape information, dimensional information, etc.) about the tubular structure 200 to be formed. The electronic file can be provided to a processing unit of a laser cutting machine. The processing unit processes the electronic file to operate a laser cutter of the laser cutting machine to cut one or more geometric patterns defined by the information in the electronic file. In some embodiments, laser cutting can be performed on the raw tube. In other cases, a raw sheet of material can be provided instead of the raw tube, and laser cutting can be performed on the raw sheet. After laser cutting, the cut sheet is rolled to form the tubular structure 200. The edges (parallel to the longitudinal axis) of the rolled sheet can be joined together to form a closed-loop tube. Other techniques include chemical etching or electrical discharge machining to create the desired pattern in the sheet or tube.

[0111] Generally, the tubular structure 200 can be manufactured from a "subtractive" process, in which material is removed from a raw tube to form openings (e.g., elongated slots) through the wall of the tube. Material removal can be accomplished by laser cutting, etching, mechanical cutting, sanding, grinding, etc. In any of these techniques, the openings formed can be considered "notches" that impart particular mechanical properties (e.g., flexibility) to the catheter 10.

[0112] In other cases, the ring element 210 and the connecting member 220 can be integrally formed with one another. For example, a mold can be provided having a rod with a protrusion on its surface. The protrusion corresponds to the space 216 formed between the ring element 210 and the connecting member 220. In that case, the material for forming the ring element 210 and the connecting member 220 is deposited on the mold. The material is then hardened to form the ring element 210 and the connecting member 220.

[0113] In yet another embodiment, the ring elements 210 and the connecting members 220 can be formed separately and then coupled together after formation. In one embodiment, multiple ring elements 210 can be provided. In this case, the ring elements 210 can be connected in series using a tubular mesh. Specifically, the ring elements 210 can be arranged in a spaced apart configuration over the tubular mesh and arranged in series along the longitudinal axis of the tubular mesh. The ring elements 210 can then be secured to the tubular mesh via adhesive, glue, welding, or the like. The portions of the tubular mesh between the ring elements 210 become and function as connecting members 220.

[0114] As mentioned above, in some embodiments, the catheter 10 can include an outer layer 260 (e.g., an outer sheath) circumferentially disposed around the tubular structure 200, and / or an inner layer 262 (e.g., an inner sheath) disposed on the interior surface of the tubular structure 200. When the catheter 10 includes both the outer layer 260 and the inner layer 262, the tubular structure 200 is sandwiched therebetween.

[0115] In some cases, the material of the outer layer 260 and / or the material of the inner layer 262 can fill the space 216 defined by the wall elements of the tubular structure 200. In such cases, the material of the outer layer 260 and / or the material of the inner layer 262 can constitute a filler material (e.g., filler material 250) that fills the space in the wall of the tubular structure 200.

[0116] For example, the filler material can be disposed in the space (e.g., gap) 216 between the ring element 210 and the connecting member 220. In some embodiments, the tubular structure 200 can be dipped into a polymer solution to fill the space 216. The polymer solution can then be cured to form the filler material. Excess filler material can be removed using chemicals, by cutting, grinding, etc.

[0117] Also, in some cases, the filler material occupying the space 216 can have a thickness that is the same as the wall thickness of the tubular structure 200. In other cases, the filler material may be thicker than the wall thickness of the tubular structure 200. In further cases, the filler material in the space 216 may be thinner than the wall thickness of the tubular structure 200.

[0118] Additionally, in some cases, the filler material may extend beyond the exterior surface of the tubular structure 200. In some cases, the filler material may be disposed on the exterior surface of the tubular structure 200 to form an outer layer (e.g., layer 260) covering the tubular structure 200. The outer layer may be integrally formed with the filler material in the space 216. In other embodiments, the outer layer is formed separately from the filler material and placed on the exterior surface of the tubular structure 200 after the filler material has been disposed (e.g., formed) in the space 216. In such cases, the outer layer may be made from the same material as the filler material or from a different material than the filler material.

[0119] Similarly, in some embodiments, the filler material may extend beyond the interior surface of the tubular structure 200. In some cases, the filler material may be disposed on the interior surface of the tubular structure 200 to form an inner layer (e.g., 260) that lines the interior wall of the tubular structure 200. The inner layer may be integrally formed with the filler material within the space 216. In other embodiments, the inner layer is formed separately from the filler material and placed on the interior surface of the tubular structure 200 after the filler material has been disposed (e.g., formed) in the space 216. In such cases, the inner layer may be made from the same material as the filler material or from a different material than the filler material.

[0120] Additionally, in some cases, ring element 210 can have the same thickness as connecting member 220. This may be the case when ring element 210 and connecting member 220 are formed from the same tube or sheet. In other cases, ring element 210 and connecting member 220 may have different thicknesses. For example, in other cases, ring element 210 may have a first thickness and connecting member 220 may have a second thickness, with the first thickness being greater or less than the second thickness.

[0121] Marker Elements FIG. 3 illustrates the marker element 240 of FIG. 2A. As illustrated, the marker element 240 includes a ring structure 300 having a distal end 301, a proximal end 302, and a body 304 extending between the distal end 301 and the proximal end 302. The ring structure 300 can be made from a radiopaque material or any material that can allow visualization of the marker device 300 using any imaging technique (e.g., X-ray, CT, MRI, ultrasound, camera, etc.). The distal end 301 of the ring structure 300 includes protruding elements 310 circumferentially disposed about the axis 340 of the ring structure 300. The proximal end 302 of the ring structure 300 is configured to couple with or extend from the tubular structure 200.

[0122] As shown in FIG. 3 , the protruding elements 310 include respective curved tip surfaces 320. The distal end 301 of the ring structure 300 further includes curved trough surfaces 330. As shown, each curved trough surface 330 is disposed between two adjacent curved tip surfaces 320. In some cases, the curved tip surfaces 320 and the curved trough surfaces 330 together form a sinusoidal profile extending circumferentially about the axis 340 of the ring structure 300. In some cases, the number of tip surfaces 320 / protruding elements 310 may be 2, 3, 4, 5, 6, 7, or 8. In other cases, the number of tip surfaces 320 / protruding elements 310 may be 9 or more.

[0123] In other embodiments, each protruding element 310 can have a different shape than the illustrated example. For example, in other embodiments, each protruding element 310 can have a rectangular shape, a partial circular shape, an elongated shape, etc. Also, in the illustrated embodiment, each protruding element 310 has a length and a width, where the length, measured parallel to the longitudinal axis 340, is less than the width of the protruding element 310. In other embodiments, each protruding element 310 has a length and a width, where the length, measured parallel to the longitudinal axis 340, is greater than the width of the protruding element 310.

[0124] As shown in the examples above, the protruding elements 310 have respective distal tips (having respective edges or tip faces 320) facing distally. In some embodiments, the distal end of the ring structure 300 can have laser cut edges.

[0125] The marker element 240 is advantageously more flexible than another marker device having the same longitudinal length and thickness as the marker element 240 and made from the same material as the marker element 240. The lack of alternating material circumferentially around the marker device 240 results in the marker element 240 having a "petal" shape with multiple protruding elements 310 (e.g., "petals"). Such a marker element 240 configuration, along with a softer polymer tip 270, results in alternating sections 396, 398 at the distal end of the catheter 10, with section 296 having harder marker material (from the marker element 240) to enable the catheter 10 to resist ovalization and section 398 having more polymer material (from the polymer tip 270) to enable the catheter 10 to achieve trackability.

[0126] The marker element 240 also has the advantage of allowing visualization under imaging, such as fluoroscopy, x-ray, or CT. The circumferentially alternating pattern achieved by the protruding elements 310 allows visualization of torsional movement of the catheter. Additionally, in one embodiment, the polymer tip 270 extends less than 3 mm, more preferably less than 2 mm, and even more preferably less than 1 mm beyond the distal-most tip of the marker element 240. Such a configuration can prevent, or at least reduce, the risk of collapsing the polymer tip 270 during aspiration and / or tracking. Furthermore, this "flush cut" design allows the physician to know exactly where the catheter tip is located during a medical procedure.

[0127] In some cases, the proximal end 302 of the ring structure 300 can optionally include tabs 400 circumferentially disposed about the axis 340 of the ring structure 300 (FIGS. 4 and 5). The tabs 400 are configured to be secured to the tubular structure 200, for example, by welding (such as spot welding), adhesive bonding, mechanical bonding, or the like. The tabs 400 are advantageous because they provide space between the marker element 240 and the tubular structure 200, which space allows for bending of the catheter 10. In the illustrated example, the marker element 240 has three tabs. In other cases, the marker element 240 can have two tabs or more than three tabs.

[0128] In some cases, the ring structure 300 of the marker element 240 has a closed-loop configuration. In such cases, the ring structure 300 has a continuous wall extending circumferentially around the axis 340. In other cases, the ring structure 300 of the marker element 240 has an open-loop configuration. For example, the ring structure 300 may have a slit extending longitudinally from the distal end 301 to the proximal end 302. Such a configuration can provide additional flexibility to the catheter 10.

[0129] FIG. 6 illustrates a variation of the marker element 240 of FIG. 4, specifically illustrating a marker device having a plurality of openings 600. The openings 600 may be holes arranged circumferentially in the body 304 of the ring structure 300. The holes may also be small through-holes extending through the wall thickness of the ring structure 300. Each hole may be a circular hole, an oval hole, a square hole, a rectangular hole, or a hole having any geometric or user-defined shape. As illustrated, the openings 600 (holes) are distributed both longitudinally (i.e., parallel to the longitudinal axis 340) and circumferentially (i.e., extending circumferentially and perpendicular to the longitudinal axis 340). In other cases, the marker element 240 may have only one row of openings 600 extending circumferentially about the axis 340. In such cases, the openings 600 are distributed circumferentially, not longitudinally.

[0130] In one embodiment, the openings 600 may be micro-holes having a cross-sectional dimension of 1 mm or less. In other cases, each of the openings 600 may have a cross-sectional dimension greater than 1 mm. The openings 600 may be formed using a laser, punching, drilling, molding, or the like. The openings 600 are advantageous because they allow material from the polymer layer 260 to be secured to the marker element 240. In some cases, the catheter 10 may include a second polymer layer (e.g., polymer layer 262 of FIG. 8). In such cases, the openings 600 allow the first polymer layer 260 to be bonded to the second polymer layer 262, thereby preventing or reducing the risk of delamination (e.g., separation between the first and second polymer layers).

[0131] As described herein, the catheter 10 can include a first polymer layer (e.g., polymer layer 260) disposed on the outer surface of the ring structure 300 and / or on at least a portion of the tubular structure 200. In such cases, a portion of the first polymer layer 260 can extend into the opening 600 (e.g., hole) of the ring structure 300. The first polymer layer 260 can extend partially into the opening 600 of the ring structure 300 or can extend completely through the wall thickness of the ring structure 300 into the opening 600. The first polymer layer 260 can extend distally beyond the distal tip of the marker element 240 to form or be bonded to the polymer tip 270.

[0132] Also, in some cases, a second polymer layer 262 (shown in FIG. 8 ) may be disposed on the inner surface of the ring structure 300. The second polymer layer 262 may extend partially into the opening 600 of the ring structure 300. In such cases, the material of the second polymer layer 262 may be bonded and connected to the material of the first polymer layer 260 at a location within the opening 600. Alternatively, the second polymer layer 262 may extend completely through the wall thickness of the ring structure 300 into the opening 600 and be bonded and connected to the first polymer layer 260. In some cases, the second polymer layer 262 may extend distally beyond the distal tip of the marker element 240 to form or be bonded to the polymer tip 270.

[0133] In some cases, the ring structure 300 can be connected to the tubular structure 200 via welding, connectors, adhesives, etc. The ring structure 300 can surround a distal portion of the tubular structure 200 and be secured to the outer surface of the tubular structure 200. Alternatively, the ring structure 300 can be partially disposed within the central lumen of the tubular structure 200 and secured to the inner surface of the tubular structure 200. In a further alternative, the proximal end of the ring structure 300 can face the distal end of the tubular structure 200, radially aligning the walls of the ring structure 300 with the walls of the tubular structure 200. In other cases, the ring structure 300 can be integrally formed with the tubular structure 200. For example, the ring structure 300 and the tubular structure 200 can be integrally molded. Alternatively, the ring structure 300 and the tubular structure 200 (or at least a portion of the tubular structure 200) can be formed together by obtaining a tube and laser cutting the tube to form the ring structure 300 and the tubular structure 200.

[0134] polymer layer As discussed above, in some cases, the catheter 10 may include a first polymer layer 260 circumferentially disposed around at least a portion of the marker element 240 and / or the tubular structure 200. Figure 7 illustrates an example cross-section of a distal segment of the catheter 10. As shown, the catheter 10 includes a first polymer layer 260 circumferentially disposed around the outer surface of the ring structure 300 of the marker element 240. The first polymer layer 260 extends proximally to also surround at least a portion of the tubular structure 200. In some cases, the polymer tip 270 is integral with the first polymer layer 260. The polymer tip 270 may be attached to the first polymer layer 260 or may be integrally formed with the first polymer layer 260.

[0135] 7, the catheter 10 further includes a second polymer layer 262 disposed on the interior surface of the marker element 240 and the interior surface of the tubular structure 200. In some cases, the polymer tip 270 is integral with the second polymer layer 262. The polymer tip 270 may be attached to the second polymer layer 262 or may be integrally formed with the second polymer layer 262.

[0136] In some cases, the first polymer layer 260, the polymer tip 270, and the second polymer layer 262 may be integral with one another. In one embodiment, the first polymer layer 260, the polymer tip 270, and the second polymer layer 262 are formed together. The first polymer layer 260 and the second polymer layer 262 may be made from the same material or different materials. Additionally, the tip polymer 270 may be made from the same material as the first polymer layer 260 and / or the second polymer layer 270. In some cases, the first material 702 of the first polymer layer 260 may extend into a space distal to the marker element 240 to form a first portion of the polymer tip 270, and the second material 704 of the second polymer layer 262 may extend into a space distal to the marker element 240 to form a second portion of the polymer tip 270. In such a case, the polymer tip 270 is made from a first material 702 of the first polymer layer 260 and a second material 704 of the second polymer layer 262. The first material 702 and the second material 704 may be the same material or may be different from one another.

[0137] The polymer layer 262 is advantageous because it provides the catheter 10 with a smooth inner lumen surface, allowing another device (e.g., another catheter, a guidewire, a treatment device, a probe, etc.) to be inserted into the lumen of the catheter 10 and easily moved relative to the catheter 10 without rubbing against or catching on components of the tubular structure 200 (which would be exposed if the catheter 10 did not include the polymer layer 262). The presence of both the polymer layer 260 and the polymer layer 262 is also advantageous because it completely encapsulates the tubular structure 200. In some cases, the polymer layer 262 can be configured with or include a hydrophilic coating to enhance lubricity. In other cases, the catheter 10 may not include the second polymer layer 262. In such cases, the tubular structure 200 has a smooth inner surface and / or the components of the tubular structure 200 have small gaps between them, allowing another device to be easily moved relative to the catheter 10.

[0138] In the above examples, the catheter 10 is described as having a marker element 240. In other cases, the catheter 10 may not include a marker element 240. In such cases, the polymer tube of the polymer tip 270 may have a proximal tube end that abuts the distal end of the tubular structure 200.

[0139] In some cases, the first polymer layer 260 can include a first segment and a second segment proximal to the first segment. The first segment can be made from NEUSoft (e.g., NEUSoft UR862A (also known as NEUSoft 62A), where "62A" refers to the hardness of the NEUSoft material). In some cases, the second segment 262 can be made from Pebax (e.g., Pebax 25D, Pebax 35D, or Pebax 45D). In some cases, the first polymer layer 260 can also include a third segment. The second segment can be made from the first Pebax, and the third segment can be made from a second Pebax that is different from the first Pebax. In further cases, the first polymer layer 260 can further include a fourth segment. The second segment may be made from a first Pebax, the third segment may be made from a second Pebax different from the first Pebax, and the fourth segment may be made from a third Pebax different from both the first and second Pebax.

[0140] In some cases, second polymer layer 262 can include a first segment and a second segment located proximally of the first segment. The first segment of second polymer layer 262 can be made from NEUSoft (e.g., NEUSoft 62A). The second segment of second polymer layer 262 can be made from PTFE.

[0141] In some cases, the first segment of the first polymer layer 260 and the first segment of the second polymer layer 262 may be made from the same material (e.g., NEUSoft). The first segment of the first polymer layer 260 and the first segment of the second polymer layer 262 may be closer to the distal end of the catheter 10 than to the proximal end of the catheter 10.

[0142] Also, in some cases, the second segment of the first polymer layer 260 and the second segment of the second polymer layer 262 are made from different respective materials, with the second segment of the first polymer layer 260 being positioned more proximal than the first segment of the first polymer layer 260 and the second segment of the second polymer layer 262 being positioned more proximal than the first segment of the second polymer layer 262.

[0143] FIG. 8 illustrates an example of the catheter 10 of FIG. 1, specifically illustrating a catheter 10 having a first polymer layer 260 and a second polymer layer 262. As illustrated, the first polymer layer 260 has a distal-most segment, a first segment 802. The first segment 802 is made from NEUSoft, such as the illustrated NEUSoft UR862A (also known as NEUSoft 62A). However, in other cases, the first segment 802 may be made from other NEUSoft materials (e.g., NEUSoft UR842A, NEUSoft UR852A, NEUSoft UR873A, etc.) or other non-NEUSoft materials. Using a NEUSoft material (or another material with properties similar to NEUSoft) for the distal-most segment of the polymer layer 260 has the advantage that the material has a relatively low modulus and high elastic properties, thereby providing the polymer layer 260 with high elasticity and flexibility. As a result, even after the catheter 10 is subjected to large bends, the polymer layer 260 is able to elastically recover without damage and / or plastic deformation.

[0144] The first polymer layer 260 also includes a second segment 804 proximal to the first segment 802, the second segment 804 being made from Pebax, such as the illustrated Pebax 25D. In other cases, the second segment 804 of the first polymer layer 260 may be made from other Pebax materials or other non-Pebax materials. The first polymer layer 260 also includes a third segment 806 proximal to the second segment 804, the third segment 806 being made from Pebax, such as the illustrated Pebax 35D. In other cases, the third segment 806 of the first polymer layer 260 may be made from other Pebax materials or other non-Pebax materials. First polymer layer 260 also includes a fourth segment 808 proximal to third segment 806, which is made from Pebax, such as the illustrated Pebax 45D. In other cases, fourth segment 808 of first polymer layer 260 may be made from other Pebax materials or other non-Pebax materials. First polymer layer 260 also includes a fifth segment 810 proximal to fourth segment 808, which is made from Coex, which is composed of Aesno and Pebax 45D. In other cases, fifth segment 810 of first polymer layer 260 may be made from other materials.

[0145] It should be noted that first polymer layer 260 is not limited to having five segments. In other cases, first polymer layer 260 may have more or less than five segments. In one embodiment, first polymer layer 260 may include only a single segment extending from the distal end to the proximal end.

[0146] As shown in FIG. 8 , the second polymer layer 262 of the catheter 10 includes a first segment 852, which is the most distal segment. The first segment 852 is made of NEUSoft, such as the illustrated NEUSoft UR862A. However, in other cases, the first segment 852 may be made of other NEUSoft materials (e.g., NEUSoft UR842A, NEUSoft UR852A, NEUSoft UR873A, etc.) or other non-NEUSoft materials. The second polymer layer 262 also includes a second segment 854 proximal to the first segment 852, which is made of PTFE. In other cases, the second segment 854 of the second polymer layer 262 may be made of other materials.

[0147] It should be noted that the second polymer layer 262 is not limited to having two segments. In other cases, the second polymer layer 262 can have more than two segments or less than two segments. In one embodiment, the second polymer layer 262 can include only a single segment extending from the distal end to the proximal end.

[0148] Also, in some cases, the first polymer layer 260 and the second polymer layer 260 may be made from the same material, such as NEUSoft, or any other type of polymer.

[0149] In some cases, the first polymer layer 260 can be made from a material having a lower modulus of elasticity than the material of the tubular structure 200. Alternatively or additionally, the material of the first polymer layer 260 can have a higher modulus of elasticity than the material of the tubular structure 200. Similarly, in some cases, the second polymer layer 262 can be made from a material having a lower modulus of elasticity than the material of the tubular structure 200. Alternatively or additionally, the material of the second polymer layer 262 can have a higher modulus of elasticity than the material of the tubular structure 200. By way of example, each of the first polymer layer 260 and the second polymer layer 262 can have an elastic (Young's) modulus of at least 2 MPa and / or up to 7 MPa, and / or a tensile elongation (tensile strain) at yield of at least 300% (=3), and / or a tensile elongation (tensile strain) at break of at least 500% (=5). In some cases, first polymer layer 260 and second polymer layer 262 may each have a modulus of elasticity (Young's modulus) in the range of 2 MPa to 7 MPa and / or a tensile elongation at yield (tensile strain) in the range of 300% to 1000%. Also, in some cases, first polymer layer 260 and second polymer layer 262 may each have a tensile strength of at least 6 MPa and / or a tensile strength of 70 MPa or less.

[0150] In the illustrated example, the first (distal-most) segment of the first polymer layer 260 and the first (distal-most) segment of the second polymer layer 262 are made from the same material. This is advantageous because the first and second polymer layers 260, 262 being the same material provides homogeneous material properties through the wall of the tubular structure 200, thereby allowing the polymer layers 260, 262 to better connect to each other through the wall openings of the tubular structure 200. In other cases, the first (distal-most) segment of the first polymer layer 260 and the first (distal-most) segment of the second polymer layer 262 may be made from different respective materials.

[0151] During use, the tubular structure 200 may be subjected to compression due to axial loading of the catheter 10 and / or bending of the catheter 10. As a result, members (formed by the material of polymer layer 260, the material of polymer layer 262, the material of the filler material, or any combination thereof) extending across the spaces 216 defined between components of the tubular structure 200 (e.g., between the ring elements 210 and the connecting members 200) may be subjected to compression. Such members may be considered polymeric members if they are composed of one or more polymers. To prevent such members from buckling (collapse) during compression, the width of the spaces 216 (measured in the direction of compression) between the components of the tubular structure 200 may be reduced by a factor of nπ 2 EI / L 2 >F, where n is a coefficient that takes into account the end conditions of the member, E is the elastic modulus of the material of the member, I is the moment of inertia of the cross section of the member, and L is the support length of the member (width of the space 216). Rewriting the above equation, the width L of the space 216 (wall gap) is L<(nπ 2 EI / F) 1 / 2 It can be expressed as:

[0152] The factor n can be 4 if the end conditions of the member are assumed to be "fixed" with respect to rotation (i.e., the ends of the member are assumed not to rotate during compression). Alternatively, the factor n can be 1 if the end conditions of the member are assumed to be "simply supported" (i.e., the ends of the member are allowed to rotate during compression), in which case the strut length L (width of space 216) would be determined more conservatively.

[0153] The modulus of elasticity E may be the modulus of elasticity of the material of polymer layer 260, the modulus of elasticity of the material of polymer layer 262, or the modulus of elasticity of the material of the filler material in space 216 that is different from polymer layers 260, 262. In some cases, when catheter 10 has all three elements (i.e., polymer layers 260, 262 and the filler material between polymer layers 260, 262) that form a member that extends across space 216, the smallest modulus of elasticity (of the three elements) can be selected for the above formula.

[0154] The moment of inertia I is the second moment of area of ​​a member's cross section. In some cases, the moment of inertia I can be calculated based on the thickness t of the member and the width w of the member (i.e., assuming the cross section is rectangular with thickness t and width w). In particular, the second moment of area I of a rectangle is wt 3 / 12.

[0155] F is the maximum compressive force to which the member will be subjected during use. In some cases, F can be determined by computer modeling or by testing prototypes.

[0156] Setting the width of the space 216 based on the above parameters is advantageous because it increases the compression resistance of the catheter 10 and allows the catheter 10 to bend with a larger curvature (i.e., a smaller radius of curvature).

[0157] In some cases, the width of the space 216 can be anywhere between 100 microns and 400 microns, more preferably between 120 microns and 300 microns, even more preferably between 140 microns and 280 microns, and even more preferably between 160 microns and 260 microns. In other cases, the space 216 can be greater than 400 microns or less than 100 microns.

[0158] Also, note that the width L of the space 216 depends on the modulus of elasticity E. If a material with a higher E is selected, the width L of the space 216 can be longer. Rewriting the above equation, L 2 <nπ 2 EI / F. Therefore, F / (nπ 2 I) <E / L 2 Therefore, the material and width L (wall clearance) of the space 216 is E / L 2 >F / (nπ 2 I) In some cases, E / L can be set to 20 to 400 N / mm 4Any value within the range of 25 to 360 N / mm 4 Any value within the range of 28 to 300 N / mm 4 Any value within the range of 30 to 280 N / mm 4 It can be anywhere in the range.

[0159] Also, in some cases, the space 216 (wall gap) can be defined as the shortest distance between adjacent elements of the tubular structure 200, such as between the ring element 210 and the connecting member 220. In some embodiments, the space 216 can be equal to or greater than the width of the ring element 210. The width of the ring element 210 can be defined as the thickness of the ring element 210 measured in a direction parallel to (or at an acute angle with) the longitudinal axis 20 and / or perpendicular to the radial direction in a cross-section of the tubular structure 200. An example of the width Wr of the ring element 210 is shown in FIG. 2B. Alternatively or additionally, the space 216 can be equal to or greater than the width of the connecting member 220. The width of the connecting member 220 can be defined as the thickness of the connecting member 220 measured in a direction parallel to (or at an acute angle with) the longitudinal axis 20 and / or perpendicular to the radial direction in a cross-section of the tubular structure 200. An example of the width Wc of the connecting member 220 is shown in FIG. 2B. In some cases, the width of the ring element 210 / connecting member 220 can be considered a kerf width (because it is the material remaining after removing a portion of the tube to create the tubular structure 200 having the ring element 210 and connecting member 220). Thus, Wr and Wc can be considered examples of kerf widths. In some embodiments, the ratio calculated as the space 216 divided by the kerf width can be anywhere in the range of 1 to 5 (e.g., at least 3, or 4, etc.). This ensures that there is enough material in the wall gap to connect the layers 260, 262 to form a laminate structure and / or to provide good compression resistance.

[0160] Tube Manufacturing Process Various techniques can be employed to manufacture tubular structure 200 and tubing having one or more polymer layers (e.g., layer 260 and / or layer 262) for catheter 10. In some cases, a coating material can be applied such that it is disposed at an opening in tubular structure 200 and forms an outer layer covering the exterior surface of tubular structure 200. The coated tubular structure 200 forms a tube. In other cases, the coating material can wrap around tubular structure 200 to form a tube. In such cases, the coating material covers the exterior surface of the tubular structure, covers the interior surface of the tubular structure, and fills openings (e.g., slots) through the wall of tubular structure 200.

[0161] In some cases, the coating material forming part of the tube can have a modulus of elasticity that is lower than the modulus of elasticity of the tubular structure 200. For example, the coating material can have a modulus of elasticity that is less than 50%, more preferably less than 30%, more preferably less than 20%, more preferably less than 10%, more preferably less than 5%, and more preferably less than 1% of the modulus of elasticity of the tubular structure 200. In one embodiment, the coating material can have a modulus of elasticity that is less than 15 MPa (e.g., 10 MPa or less).

[0162] The coating material forming part of the tube may also have the ability to stretch significantly before yielding. For example, in some embodiments, the coating material may have a strain (defined as the amount of elongation in the material divided by the length of the material) of at least 20%, 40%, 60%, 80%, 100%, 200%, 300%, 400%, 500%, 600%, 700%, 800%, 900%, 1000%, or more.

[0163] A variety of coating materials can be used. Non-limiting examples of coating materials include polyurethane, polyurethane-based materials, silicone-based materials, any material having a polyurethane dispersion or a silicone-based dispersion, etc. Examples of coating materials that can be used include Covestro's CD102® or AD111®, Gelest's Gelest Ex-sil50®, NEUSoft (e.g., NEUSoft 42A, NEUSoft 52A, NEUSoft 62A, NEUSoft 73A, etc.), and Pebax (e.g., Pebax 25D, Pebax 35D, or Pebax 45D, etc.).

[0164] In some embodiments, tubular structure 200 is configured to be significantly more flexible than the polymer tube (formed by layers 260 and / or 262). In such cases, the resulting tube has one or more mechanical properties contributed primarily (e.g., greater than 50%, greater than 60%, greater than 70%, greater than 80%, greater than 90%, etc.) by the polymer tube. By way of non-limiting example, the one or more mechanical properties may include bending stiffness, axial stiffness, torsional stiffness, shear stiffness, or any combination thereof. In some cases, the stiffness of the tube formed by the polymer tube (composed of layers 260 and / or 262) and tubular structure 200 may be at least four times, more preferably at least eight times, even more preferably at least twelve times, and even more preferably at least sixteen times, the stiffness of tubular structure 200 alone (i.e., without the polymer tube). In some embodiments, the material or materials of the polymer tube have a relatively lower modulus and higher elasticity than the material of tubular structure 200. Nevertheless, the stiffness of the tube formed by the polymer tube and the tubular structure 200 is at least four times the stiffness of the tubular structure 200 alone.

[0165] In one or more embodiments, the tube may optionally further include a hydrophilic coating disposed on the outer surface of the tube and / or on the inner surface of the tube. In some cases, an initial coating material may first be applied onto the tubular structure 200 to fill openings in the wall of the tubular structure 200 and optionally cover the outer and / or inner surfaces of the tubular structure 200. A hydrophilic coating is then applied over the initial coating material.

[0166] Using a tubular structure 200 to construct the tube (which provides most of the mechanical properties) and a very soft coating material is advantageous because it prevents the distal end of the tube from becoming too stiff, easing the design of the catheter and, as a result, making the catheter's behavior more predictable (computational modeling of the catheter can be based solely on the design of the tubular structure).

[0167] Various techniques can be employed to apply the coating material to the tubular structure 200. For example, in certain embodiments, a polymer extrusion can be applied or assembled to the interior and / or exterior surfaces of the tubular structure 200 and remelted and laminated around it, thereby encasing the tubular structure 200. In one embodiment, the polymer extrusion can be applied to both the interior and exterior surfaces of the tubular structure 200. The polymer extrusion can then be heated to fill the interstices in the wall of the tubular structure 200 with the polymer material, thereby connecting the polymer layers on either side of the wall of the tubular structure 200 through the interstices in the wall of the tubular structure 200 to form a laminated structure that encases the entire tubular structure 200.

[0168] In some cases, deposition techniques may be employed to deposit the coating material onto the tubular structure 200. In other cases, a dipping process may be utilized to apply the coating material onto the tubular structure 200.

[0169] In some cases, when applying a coating material onto the tubular structure 200 using a dipping technique, a barrier may be provided inside the central lumen of the tubular structure 200 to prevent the coating material from flowing into the central lumen. For example, in some embodiments, the inner surface of the tubular structure 200 may be masked to prevent coating material from outside the tubular structure 200 from flowing into the central lumen through openings in the wall of the tubular structure 200. In other embodiments, a tube or rod may be placed within the central lumen of the tubular structure 200 to act as a barrier to prevent the coating material from flowing into the central lumen. The tube or rod may be made of PTFE, HDPE, stainless steel, or any other suitable material.

[0170] The tubular structure 200 can then be placed in a reservoir of coating material in liquid or viscous form. The coating material can be tailored to have a specific viscosity to aid in the coating process. In some cases, the tubular structure 200 can be positioned vertically in the reservoir, with the longitudinal axis of the tubular structure 200 at an angle of 90°±25° relative to the top surface of the liquid in the reservoir. In other cases, the tubular structure 200 can be positioned horizontally in the reservoir, with the longitudinal axis of the tubular structure 200 at an angle of 0°±25° relative to the top surface of the liquid. In other cases, the tubular structure 200 can be positioned in the reservoir at other angles different from the above examples.

[0171] In some cases, the tubular structure 200 can be inserted into the reservoir at a specific speed, such as within a range of 0.01 cm / sec to 5 cm / sec. In other cases, the tubular structure 200 can be inserted at a speed slower or faster than the above range. Also, in some cases, the tubular structure 200 can be rotated at a specific speed, for example, 2 to 10 revolutions per minute, as it is inserted into the reservoir. In other cases, the rotation speed can be slower or faster than 2 to 10 revolutions per minute. In still other cases, the tubular structure 200 can be prevented from rotating as it is inserted into the reservoir.

[0172] After immersion of the tubular structure 200 in the reservoir of coating material, the tubular structure 200 can be removed from the reservoir. In some cases, the tubular structure 200 can be removed from the reservoir at a specific speed, for example, anywhere within a range of 0.01 cm / sec to 10 cm / sec. In other cases, the tubular structure 200 can be removed from the reservoir at a speed slower or faster than the above range. Also, in some cases, the tubular structure 200 can be rotated at a specific speed, for example, 2 to 10 revolutions per minute, as the tubular structure 200 is removed from the reservoir. In other embodiments, the rotation speed can be slower or faster than 2 to 10 revolutions per minute. In further cases, the tubular structure 200 can be removed from the reservoir without rotation.

[0173] Tubular structure 200 is immersed in and removed from the reservoir, thereby disposing a first layer of coating material (e.g., layer 260) on the exterior surface of tubular structure 200. The coating material also extends to and fills openings in the wall of tubular structure 200.

[0174] After the tubular structure 200 is removed from the reservoir, the tubular structure 200 containing the coating material is held at a specific temperature for a specific time to solidify the coating material. The time for the coating material to solidify can be anywhere from 1 minute to 120 minutes. In other embodiments, the solidification time can be less than 1 minute or more than 120 minutes. In some cases, the temperature for solidifying the coating material can be anywhere from 20°C to 100°C. In other cases, the temperature for solidifying the coating material can be less than 20°C or greater than 100°C.

[0175] In some cases, the insertion of the tubular structure 200 into the reservoir and the removal of the tubular structure 200 from the reservoir can be repeated one or more times (e.g., anywhere from 1 to 30 times or more) until a desired thickness of coating material is achieved. In some cases, the thickness of the coating material formed on the outer surface of the tubular structure 200 is anywhere from 0.0001 inches to 0.003 inches or more.

[0176] In some cases, application of the coating material to the tubular structure 200 can be performed in a vacuum. For example, in some cases, a reservoir of the coating material is located in a vacuum chamber, and the tubular structure 200 can be dipped and removed in the vacuum chamber. Solidification of the coating material can also be performed in the vacuum chamber.

[0177] In some cases, after the coating material has solidified, a hydrophilic coating can be applied over the solidified coating. Application of the hydrophilic coating can be accomplished using dipping techniques similar to those described above. In other cases, deposition techniques can be used to apply the hydrophilic coating over the solidified coating. The hydrophilic coating can be applied to the exterior surface of the tube 11 and / or the interior surface of the tube 11. In some cases, the hydrophilic coating can be considered part of the tube 11.

[0178] It should be noted that the process for coating the tubular structure 200 is not limited to the examples described above, and the tubular structure 200 can be coated using other techniques or variations of the techniques described above. For example, in other cases, a barrier may not be provided within the central lumen of the tubular structure to prevent the coating material from entering the central lumen. Instead, the coating material is allowed to flow into the central lumen during the immersion process. In such cases, after removing the tubular structure 200 from the reservoir, and before the coating material in the central lumen of the tubular structure 200 solidifies, excess material in the central lumen can be removed by placing a plunger inside the central lumen and moving it longitudinally through the tubular structure 200. In some cases, all of the coating material in the central lumen is removed so that no coating material remains on the inner surface of the tubular structure 200. In other cases, some, but not all, of the coating material in the central lumen is removed, leaving a layer of coating material (e.g., layer 262) on the inner surface of the tubular structure 200. In a further embodiment, removal of excess coating material within the central lumen of the tubular structure 200 can be accomplished using a cutter after the coating material has solidified.

[0179] In other cases, a rod or tube (smaller than the size of the central lumen of the tubular structure 200) can be placed within the central lumen of the tubular structure 200 before inserting the tubular structure 200 into the reservoir of coating material. The rod or tube has an outer surface spaced apart from the inner surface of the tubular structure 200. This allows the coating material to fill the space between the rod / tube and the inner surface of the tubular structure 200, thereby forming a layer of coating (e.g., layer 262) on the inner surface of the tubular structure 200. The coating material also fills the openings in the wall of the tubular structure 200 and extends outside the tubular structure 200 to form a layer of coating (e.g., layer 260) on the outer surface of the tubular structure 200.

[0180] In further cases, instead of using a dipping technique, the coating material can be pumped to cover the entire tubular structure 200 at a specific flow rate to form a coating of the desired thickness.

[0181] How to use The catheter 10 described herein may be any type of catheter in various embodiments. For example, the catheter 10 may be an implant delivery catheter configured to deliver an implant, such as for treating an aneurysm. As another example, the catheter 10 may be a guide catheter configured to be delivered over a guidewire and also configured to deliver a medical tool. As a further example, the catheter 10 may be a drug delivery catheter configured to deliver a drug or a biopsy catheter configured to transport tissue removed from within a patient's body.

[0182] In some embodiments, the catheter 10 described herein can be utilized to access the vascular system within a patient. During use, the distal end of the catheter 10 is inserted into a patient's blood vessel and advanced distally within the vessel. In some cases, a guidewire has already been advanced into the patient's body until it reaches the target site. In such cases, the catheter 10 can be advanced over the guidewire until its distal end reaches the target site. Alternatively or additionally, a guide catheter can first be inserted into the blood vessel and advanced to the desired location within the patient's body. The catheter 10 can then be placed within the guide catheter and advanced within the guide catheter until its distal end reaches the target site.

[0183] In some embodiments, the catheter 10 can be used to assist in the insertion and guidance of an interventional device into a selected vessel in the neurovasculature or to assist in the removal of a thrombus and recanalization of a vessel in a patient experiencing an acute ischemic stroke. The catheter 10 is pre-humidified and flushed before being inserted into the lumen of a guide catheter already inserted into the patient's body. The catheter 10 is advanced until the tip of the catheter 10 reaches the target location. In some cases, while the catheter 10 is within the guide catheter, the catheter 10 may include a neurointervention guidewire and / or a delivery assistant catheter within its lumen. Alternatively, if a wire (e.g., a guidewire) and / or a delivery assistant catheter is used, the tip of the wire and / or the tip of the delivery assistant catheter may be advanced first and rotated to orient the tip toward the target vessel. The catheter 10 may then be advanced over the wire and / or the delivery assistant catheter. Alternatively, the catheter 10 may be advanced directly into the target vessel without the use of a guide catheter and / or a wire (e.g., a guidewire). In such cases, catheter 10 may or may not include a wire (eg, a guidewire such as a neurointerventional guidewire) and / or a delivery assistance catheter in its lumen.

[0184] As the catheter 10 is navigated through the vasculature, it may be subjected to bending, tension, and compression. As these occur, adjacent ring elements 210 move relative to one another. In particular, when the catheter 10 is under tension, adjacent ring elements 210 move away from one another. When the catheter 10 is under compression, adjacent ring elements 210 move toward one another. When the catheter 10 is bent, adjacent ring elements 210 rotate relative to one another. When the catheter 10 is subjected to tension and bending, the auxetic angles of the ring elements 210 prevent the catheter lumen from collapsing, as described herein.

[0185] Additionally, as adjacent ring elements 210 move relative to one another, the connecting members 220 between the adjacent ring elements 210 also move relative to the adjacent ring elements 210. As a result, the angle between the connecting members 220 and the ring elements 210 to which they are connected changes (i.e., decreases or increases). The connecting members 220 transfer stress between adjacent ring elements 210 and maintain the structural integrity of the tubular structure 200. If the width (dimension measured along a direction perpendicular to the radial axis of the tubular structure 200) of the connecting members 220 is smaller than the thickness (dimension measured along the radial direction of the tubular structure 200), the movement of the connecting members 220 will be in a direction perpendicular to the radial axis of the tubular structure 200 (e.g., tangential to the cross-section of the tubular structure 200). This has the advantage of preventing the connecting members 220 from moving radially (e.g., inward toward the lumen of the catheter 10 or outward toward the exterior surface of the catheter 10).

[0186] Additionally, as the catheter 10 is guided through a blood vessel, the polymer material (filler) in the space between the ring elements 210 and the connecting members 220 transfers stress between the ring elements 210 and the connecting members 220. In some cases, the transferred stress may be compressive. In such cases, the length of the polymer filler (which is equal to the width of the space between the ring elements 210 and the connecting members 220) is configured based on one or more buckling parameters described herein so that the polymer filler does not buckle in response to compression.

[0187] After the catheter 10 is positioned within the patient's body as desired, it can be utilized with one or more items to treat a medical condition. For example, the catheter 10 can deliver an implant, such as for treating an aneurysm. As another example, the catheter 10 can deliver a medication to treat a medical condition within the patient's body. As a further example, the catheter 10 can deliver devices such as guidewires, therapeutic devices, diagnostic tools, etc. In other embodiments, the catheter 10 can deliver tissue harvested from within the patient's body. The polymer layer disposed within the inner wall surface of the tubular structure 200 provides a smooth surface that facilitates the delivery of one or more items within the lumen of the catheter 10.

[0188] As used herein, the term "relaxed state" (e.g., the relaxed state of a tubular structure, the relaxed state of a catheter, etc.) refers to the state of an object when no external forces (other than gravitational forces) are applied to the object. For example, the relaxed state of a tubular structure / catheter can refer to the state of the tubular structure / catheter resting on a surface with no bending, axial, or torsional forces acting on the tubular structure / catheter.

[0189] While particular embodiments have been disclosed and described, it should be understood that this is not intended to limit the invention to the preferred embodiments. Furthermore, it will be apparent to those skilled in the art that various changes and modifications (e.g., the dimensions and / or shape of various parts) can be made without departing from the spirit and scope of the invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. The invention is intended to cover alternatives, modifications, and equivalents.

Claims

1. A catheter, a tubular structure having a first ring element, a second ring element, and a third ring element; the tubular structure includes a first set of connecting members between the first ring element and the second ring element; the tubular structure includes a second set of connecting members between the second ring element and the third ring element; the second ring element comprises a first ring portion and a second ring portion, each of the first and second ring portions extending in a direction that is not perpendicular to a longitudinal axis of the tubular structure, the first ring portion and the second ring portion together forming a non-planar configuration of the second ring element.

2. The catheter of claim 1, The catheter, wherein the first ring portion and the second ring portion are different respective circumferential portions of the second ring element.

3. The catheter of claim 1, The catheter is characterized in that the first ring portion has a first flat portion lying in a first plane, the second ring portion has a second flat portion lying in a second plane different from the first plane, and the first plane and the second plane each form an angle that is not perpendicular to a longitudinal axis of the catheter.

4. The catheter of claim 1, the second ring element also includes a junction portion between the first ring portion and the second ring portion, the junction portion including a central portion, a first portion, and a second portion, the first portion and the second portion being on opposite sides of the central portion.

5. The catheter according to claim 4, A catheter, wherein the first and second portions of the junction are curved in opposite directions.

6. The catheter according to claim 4, A catheter, characterized in that a central portion of the joint portion is configured to rotate and / or resist moments when the catheter is under tension or when the catheter is bent.

7. The catheter of claim 1, the first set of connecting members and the second set of connecting members are configured to move relative to the second ring element when the catheter is bent and / or when an axial load is applied to the catheter.

8. The catheter of claim 1, A catheter, wherein one of the first set of connecting members has a width and a thickness, the width being less than the thickness.

9. The catheter of claim 1, A catheter characterized in that the total number N of the first sets of connecting members satisfies the condition N≧F / (S×A), where F is the axial load on the catheter, S is the allowable axial stress on each of the first sets of connecting members, and A is the cross-sectional area of ​​one of the connecting members.

10. The catheter of claim 1, A space between one of the first set of connecting members and the second ring element has a width L, and the width L of the space satisfies the following relationship: L<(nπ ２ EI / F) １／２ where n is 4 or less, E is the elastic modulus of the material of the polymer structure spanning the space, F is the axial load acting on the polymer structure, and I is the moment of inertia of the cross section of the polymer structure.

11. The catheter of claim 1, a space between one of the first set of connecting members and the second ring element having a width L, the catheter further comprising a polymer structure spanning the space, the polymer structure having a modulus of elasticity E and a ratio E / L ２ is F / (nπ ２ I) <E / L ２ where F is the axial load on the polymer structure, n=4 or less, and I is the moment of inertia of the cross section of the polymer structure.

12. The catheter of claim 1, The catheter further comprising a marker element attached to or extending from the distal end of the tubular structure.

13. The catheter of claim 12, a polymer layer bonded to the tubular structure, the polymer layer extending distally beyond the distal tip of the marker element to form a polymer tip, the polymer tip extending less than 3 mm beyond the distal tip of the marker element.

14. The catheter of claim 1, The catheter further comprising a first polymeric layer circumferentially disposed about an outer surface of the tubular structure.

15. 15. The catheter of claim 14, A catheter characterized in that the first polymer layer has a modulus of elasticity of at least 2 MPa and / or up to 7 MPa, a tensile elongation at yield of at least 300%, a tensile elongation at break of at least 500%, or any combination thereof.

16. 15. The catheter of claim 14, The catheter further comprising a second polymer layer disposed on the interior surface of the tubular structure.

17. 17. The catheter of claim 16, A catheter characterized in that the second polymer layer has a modulus of elasticity of at least 2 MPa and / or up to 7 MPa, a tensile elongation at yield of at least 300%, a tensile elongation at break of at least 500%, or any combination thereof.

18. 17. The catheter of claim 16, the first polymer layer and the second polymer layer form a tube that encases the entire tubular structure; A catheter characterized in that the material of the tube has a higher elastic modulus than the material of the tubular structure and is more elastic than the material of the tubular structure.

19. 20. The catheter of claim 18, A catheter characterized in that the stiffness of the combination of the tubular structure and the tube is at least four times the stiffness of the tubular structure alone.

20. The catheter of claim 1, A catheter characterized in that the tubular structure has a wall gap to calf width ratio in the range of 1 to 5.

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