Embolization microcatheter for delivering large microspheres

Abstract

An embolization microcatheter having: a wall including a braid, a polymer formed around the braid, and a liner covering the inner surface of the wall; a radiopaque marker located near the distal opening; wherein a portion of the microcatheter extending between the proximal end of the radiopaque marker and the distal opening is without a liner, and wherein the wall has a thickness of about 120 microns or less.

Description

Field of the Technology

[0001] This disclosure generally relates to the field of microcatheters for embolization, and more particularly to large-diameter embolization catheters suitable for delivery through a standard delivery catheter. Background Art

[0002] Transarterial embolization therapy, tumor embolization, or transcatheter arterial embolization (TAE) involves the direct administration of an embolization material (which may include chemotherapy or / and radiotherapy) to a tumor (e.g., a liver tumor) via a microcatheter.

[0003] Since there is a need to selectively affect the tumor while minimizing damage to healthy tissue as much as possible, embolization of tumors is typically performed using a microcatheter. The main problem associated with embolization is "non-target embolization", in which the embolization material travels to vessels other than those directly supplying blood to the target tumor or target tumor area, thus damaging healthy tissue and resulting in uncomfortable and even dangerous outcomes. Possible scenarios include gastric ulcers caused by liver embolization and the situation where the embolization material refluxes along the microcatheter to the gastric wall, which may lead to ischemia and ulcers. An additional phenomenon that is common especially in advanced liver cancer is non-target embolization through arteriovenous shunts.

[0004] Microcatheters are typically delivered through a larger-lumen catheter placed within the proximal portion of a blood vessel, such as the celiac artery or the hepatic artery, and then the microcatheter advances through it towards the tumor until it reaches the target location. In some scenarios, it is advantageous to use a diagnostic catheter as the delivery medium for the microcatheter. This process eliminates the need to change one catheter for another, thus saving a significant amount of time.

[0005] Another reason for the routine use of microcatheters in embolization procedures is the size of the blood vessels supplying the tumor, which can directly transport blood to an organ or a tumor. To get as close as possible to the tumor, the embolization catheter is advanced into smaller and sometimes tortuous blood vessels. It is difficult (if not impossible) to access these vessels with larger and usually stiffer catheters. Moreover, blood vessels in the body tend to spasm when being manipulated, resulting in ineffective delivery of the embolization material. Therefore, flexible micro-sized catheters are absolutely necessary.

[0006] The main drawback of transcatheter embolization is that the usually invisible embolization material may reflux and reach non-target tissues and cause damage to them. In addition, the reflux of the embolization material may negatively affect the delivery of the embolization material to the target tissue and thus compromise the therapeutic effect and its clinical outcome.

[0007] The inventors of the present application have disclosed a microcatheter having a filter section for delivering embolization microspheres while preventing the backflow of the microspheres. However, such catheters have proven unsuitable for delivering these microspheres due to large embolization microspheres clogging the microcatheter, and a simple increase in the outer diameter of the microcatheter renders them unsuitable for delivery through standard delivery catheters, such as a 5.0 French delivery catheter. Summary of the Invention

[0008] The present disclosure relates to an embolization microcatheter that is suitable for delivery through a 5.0 French delivery catheter and that also facilitates the delivery of large embolization microspheres, i.e., microspheres having a particle size of 900 microns or greater.

[0009] This is advantageously achieved through a unique structure of the wall of the embolization microcatheter.

[0010] The wall is made of a polymeric material that surrounds a braid, which provides the microcatheter with (especially along its filter section) structural integrity and trackability. The wall also includes a lining that covers the inner surface of the wall and is configured to reduce friction between the wall and the flowing microspheres. However, the thickness of the wall remains below about 120 microns (at least along the portion thereof that passes through the delivery microcatheter). The main obstacle to maintaining the thickness of the wall is the radiopaque marker located near the distal opening of the microcatheter. The inventors of the microcatheter disclosed herein have surprisingly found that the desired thin wall can be achieved and maintained by having the lining extend only up to the radiopaque marker to avoid bulging, and that the portion of the microcatheter extending from the radiopaque marker to the distal opening has a minimal or no effect on the delivery of microspheres through the distal opening.

[0011] The embolization microcatheter disclosed herein may further include a filter section having a plurality of openings that are configured for fluid outflow while preventing the outflow of microspheres, thereby ensuring the concentrated delivery of embolization microspheres and minimal backflow.

[0012] Advantageously, the size, shape, and distribution of the openings are such that the microspheres can be delivered smoothly despite their large size. This is achieved by including two or more filter sections, each filter section including a plurality of side openings having a closest circumferential section that is circumferentially distributed around the microcatheter, wherein the closest circumferential section includes fewer side openings than the section distal thereto. Thus, the outflow of fluid is relatively low at the proximal end of the filter, thereby reducing the chance of clogging, and increases towards the distal opening, where a low outflow rate is desired to prevent backflow. In addition, the shape and size of the openings vary between the proximal and distal ends of the filter, as the farthest part of the filter includes small, preferably square, openings that are configured to prevent the microspheres from getting stuck and / or being aspirated as the volume of the suspension decreases.

[0013] Some aspects of the present disclosure provide an embolization microcatheter, comprising: an elongate tubular member forming a lumen, the elongate tubular member terminating in a distal opening, wherein the wall of the elongate tubular member comprises a braid, a polymer formed around the braid, and a liner covering the inner surface of the wall; wherein the wall of the portion of the elongate tubular member extending between the proximal radiopaque marker and the distal opening has a thickness less than or equal to 130 microns; and a distal radiopaque marker located near the distal opening; wherein the portion of the elongate tubular member extending between the proximal end of the radiopaque marker and the distal opening has no liner.

[0014] According to some embodiments, the outer diameter of the elongate tubular member is less than or equal to 1.5 mm and the inner diameter of the elongate tubular member is 700 microns or greater.

[0015] According to some embodiments, the thickness of the distal end of the wall is less than or equal to 120 microns.

[0016] According to some embodiments, the embolization microcatheter comprises a filter formed in the wall of the elongate tubular member, the filter comprising two or more filter segments, each filter segment comprising a plurality of side openings penetrating the wall, the plurality of side openings being circumferentially distributed around the elongate tubular member.

[0017] According to some embodiments, the proximal-most filter segment among these filter segments comprises fewer side openings than the side openings of the distal loops thereof.

[0018] According to some embodiments, the farthest filter segment is positioned proximally about 2 - 4 mm from the distal opening.

[0019] According to some embodiments, the side openings of the farthest filter segment are substantially square. According to some embodiments, the substantially square side openings have a size of 50×50 microns. According to some embodiments, the substantially square side openings have a cross-sectional size of 80×50 microns.

[0020] According to some embodiments, the side openings of the remaining filter segments of at least two filter segments are in the form of axial slits.

[0021] According to some embodiments, the side openings of the remaining filter segments of at least two filter segments have a width of 20 microns, and wherein the lengths of the side openings of the remaining filter segments of at least two filter segments are different between these side openings.

[0022] According to some embodiments, the side openings of the remaining filter segments of at least two filter segments have a length of at least 200 microns.

[0023] According to some embodiments, at least some of the side openings of the remaining filter segments of at least two filter segments have a size of 2700×20 microns.

[0024] According to some embodiments, at least some of the side openings of the remaining filter sections of the at least two filter sections have a size of 1350×20 microns. According to some embodiments, at least some of the side openings of the remaining filter sections of the at least two filter sections have a size of 300×20 microns.

[0025] According to some embodiments, the braid can be made of tungsten.

[0026] According to some embodiments, the inner lining includes polytetrafluoroethylene (PTFE).

[0027] According to some embodiments, the radiopaque marker includes a metallic marker band. According to some embodiments, the radiopaque marker is positioned proximally 0.5 - 2 mm from the distal opening.

[0028] According to some embodiments, the embolization microcatheter is suitable for delivering embolization microspheres having a particle size of approximately 900 microns.

[0029] According to some embodiments, the embolization microcatheter has a length of at least 1 m.

[0030] According to some embodiments, a method for delivering embolization microspheres is provided, the method comprising: delivering the embolization microcatheter disclosed herein through a delivery catheter to a target location; and injecting microspheres through the microcatheter.

[0031] According to some embodiments, the microspheres have a particle size of at least 500 microns. According to some embodiments, the microspheres have a particle size of at least 900 microns.

[0032] According to some embodiments, the delivery catheter is a 5.0Fr delivery catheter.

[0033] Certain embodiments of the present disclosure may include some, all, or none of the above features. One or more technical advantages will be apparent to those skilled in the art from the accompanying drawings, the specification, and the claims included herein. Additionally, although specific features have been listed above, various embodiments may include all, some, or none of the listed features.

[0034] In addition to the exemplary aspects and embodiments described above, other aspects and embodiments will be further elaborated in the drawings and the detailed description below. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] When combined with the accompanying drawings, the features, nature, and advantages of the present disclosure will become more apparent from the following detailed description. Throughout the drawings, like reference numerals correspondingly identify. The same structure, element, or part that appears in more than one figure is generally labeled with the same number in all the figures in which it appears. Alternatively, an element or part that appears in more than one figure may be labeled with different numbers in the different figures in which it appears. The sizes of the components and features in the figures are chosen for convenience and clarity of presentation and are not necessarily shown to scale. The figures are listed as follows.

[0036] Figure 1A Schematically illustrates a microcatheter including an outer layer according to some embodiments, the outer layer including a plurality of segments made of different polymeric materials;

[0037] Figure 1B Schematically illustrates Figure 1A A perspective cross-sectional view of the distal end of a microcatheter, illustrating the outer layer, the strike layer, the inner layer, and the braided skeleton located between the inner layer and the outer layer.

[0038] Figure 2A Schematically illustrates a 3.0Fr embolization microcatheter having a fluid barrier forming segment according to some embodiments.

[0039] Figure 2B Schematically illustrates according to some embodiments Figure 2A An enlarged and partially exposed view of the distal end of a microcatheter.

[0040] Figure 2C Schematically illustrates according to some embodiments Figure 2A An enlarged and partially exposed view of the distal tip of a microcatheter.

[0041] Figure 2D Schematically illustrates a slit formed by selectively cutting through the wall of a fluid barrier forming segment, such as cutting through Figure 2A The fluid barrier forming segment of an embolization microcatheter.

[0042] Figure 3 Schematically illustrates Figure 2A An optional slit pattern of a microcatheter.

[0043] Figure 4 Schematically illustrates Figure 2A Another optional slit pattern of a microcatheter. Detailed Description

[0044] The following detailed description in conjunction with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein can be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without the specific details presented herein. In some instances, well-known features may be omitted or simplified to avoid obscuring the disclosure.

[0045] Reference is now made to Figure 1A , which schematically illustrates an embolization microcatheter 100, and reference is made to Figure 1B , which illustrates an Figure 1A enlarged / exposed view of the distal portion of

[0046] As used herein, the terms “embolization,” “transcatheter embolization,” “transcatheter arterial embolization,” and “TAE” may be used interchangeably and refer to the passage and retention of an embolus within the bloodstream for therapeutic purposes (e.g., as a hemostatic treatment for bleeding or as a treatment for certain types of cancer by intentionally blocking blood vessels to starve tumor cells).

[0047] The embolization microcatheter 100 is a 3.0Fr microcatheter 110 having an elongate tubular member with an outer diameter of about 1.5 mm, or an outer diameter in the range of 1.0 - 1.5 mm, or 1.2 - 1.6 mm and an inner diameter in the range of 700 - 850 microns.

[0048] The proximal end 130 of the microcatheter 100 includes a hub 102 that is formed on or otherwise attached to the elongate tubular member 110 of the microcatheter 100.

[0049] The hub 102 is configured to allow access to the lumen of the elongate tubular member 110 for various functions such as injecting fluids or drugs, or introducing a guide wire. The hub 102 includes a strain relief device 112 that is preferably mechanically coupled to the hub 102. The strain relief device 112 may be made of a polymeric material and, as shown, may be tapered at its distal end. The strain relief device 112 may be configured to provide structural support to the elongate tubular member 110 to prevent it from kinking.

[0050] According to some embodiments, the wall of the elongate tubular member 110 may include a plurality of sections, each section characterized by the polymer used. According to some embodiments, the plurality of sections may include 3, 4, 5, 6, 7, 8, 9, 20, or more sections. Each possibility is a separate embodiment.

[0051] According to some embodiments, different polymer layers can contribute to different characteristics of the layer / section and thus of the elongate tubular member 110. For example, different polymer layers can contribute to the elasticity, flexibility, tensile ability, strength, hardness, stiffness, ultimate tensile strength, elongation, or any other characteristic of the layer and thus of the microcatheter. Each possibility is a separate embodiment.

[0052] The proximal end 130 of the elongate tubular member 110 is attached to a strain relief device 112, including an outer layer 132 made of a polyether block amide having a Shore hardness of about 70D and / or a flexural modulus of about 74,000 psi. According to some embodiments, the proximal end 132 can have a length of 600 - 1200 mm (e.g., about 1000 mm).

[0053] Optionally, a portion of the outer layer 132 can include a heat shrink material 134 that covers the junction between the strain relief device 112 and the elongate tubular member 110.

[0054] Adjacent to the section 132 is a second section 136 of the elongate tubular member 110, made of a polyether block amide having a Shore hardness of about 60D - 65D and / or a flexural modulus of about 41,000 psi. The length of the section 136 can be 20 - 60 mm, e.g., 40 mm.

[0055] The intermediate portion 140 of the elongate tubular member 110 includes: a section 142 having an outer layer that can be made of a polyether block amide or other suitable polymer having a Shore hardness of 55D and / or a flexural modulus of about 25,000 psi; a section 144 having an outer layer made of a polymeric material having a Shore hardness of 40D (such as a polycarbonate-based thermoplastic polyurethane having a Shore hardness of about 40D) and / or a flexural modulus of about 10,000 - 12,000 psi; a section 146 having an outer layer made of one or more polycarbonate-based thermoplastic polyurethanes having a Shore hardness of about 95A; and a section 148 having an outer layer made of one or more polycarbonate-based thermoplastic polyurethanes having a Shore hardness of about 85A.

[0056] The length of the section 142 can be from about 30 mm to about 80 mm, e.g., 40 mm. The length of the section 144 can be 30 mm to about 70 mm, e.g., about 50 mm. The length of the section 146 can be 80 mm to about 150 mm, e.g., about 130 mm. The length of the section 148 can be 20 mm to about 60 mm, e.g., about 45 mm.

[0057] According to some embodiments, the distal end can refer to the distal 100 mm, 50 mm, 30 mm, 20 mm, 15 mm, 10 mm, 5 mm, or 2 mm of the microcatheter 100. Each possibility is a separate embodiment. According to some embodiments, the distal end can refer to the portion of the microcatheter that extends between the proximal marker and the distal opening 180.

[0058] According to some embodiments, the polymeric material of all sections in the intermediate portion 140 is softer than the polymeric material of the wall sections in the proximal end 130 of the tubular member 110.

[0059] According to some embodiments, the polymeric material of section 148 is softer than the polymeric material of section 146. According to some embodiments, the polymeric material of section 146 is softer than the polymeric material of section 144. According to some embodiments, the polymeric material of section 144 is softer than the polymeric material of section 142.

[0060] The distal end 150 of the elongate tubular member 110 includes a section 152 having an outer layer made of a polymeric material having a Shore hardness of 85A (such as a polycarbonate-based thermoplastic polyurethane having a Shore hardness of about 85A). The polymer of section 152 can further include a radiopaque marker of the polymer, such as but not limited to tantalum powder; section 154 has an outer layer made of a polymeric material having a Shore hardness of 95A (such as a polycarbonate-based thermoplastic polyurethane having a Shore hardness of about 95A). According to some embodiments, the distal tip 170 of the elongate tubular member 110 terminates at a distal opening. According to some embodiments, the distal tip refers to the distal marker 162 and the distal opening 180.

[0061] As used herein, the term "distal opening" refers to the end opening of the microcatheter that leads to its lumen. According to some embodiments, the distal opening 180 defines the terminus of the microcatheter at its distal end. According to some embodiments, the inner diameter of the distal opening 180 can be substantially equal to the inner diameter of the microcatheter lumen. According to some embodiments, the inner diameter of the distal opening 180 can be less than the inner diameter of the microcatheter lumen, resulting in the lumen narrowing towards its end.

[0062] Section 152 includes a proximal marker 160 (see Figure 1B ), section 154 terminates at a distal marker 162 (also see Figure 1B)。According to some embodiments, the length of section 150 can be 10 - 20 mm. According to some embodiments, the length of section 152 can be 2 - 10 mm (e.g., about 6 mm). According to some embodiments, the length of section 154 can be 5 - 20 mm (e.g., about 10 mm). According to some embodiments, the proximal marker 160 can be a radiopaque powder embedded in a portion of the outer layer of section 152, substantially as described herein. According to some embodiments, the proximal marker 160 can be positioned at about 5 - 20 mm or 10 - 15 mm from the distal opening 180. According to some embodiments, the distal marker 162 can be a radiopaque alloy immersed in the outer layer 154 of the section. According to some embodiments, the distal marker 162 can be positioned proximally about 1 mm from the distal opening 180.

[0063] Reference is now made to Figure 1B , which schematically shows Figure 1A a perspective cross-sectional view of the distal portion of the distal end 150 of the microcatheter 100 shown, the distal portion extending from the proximal marker 160 to the tip 170 and surrounding section 154 of the elongated tubular member 110. The wall of section 154 is as described above. As seen from the exploded view, below the outer layer is the braid 190.

[0064] According to some embodiments, the braid 190 extends along the entire length of the tubular member 110. Alternatively, the braid 190 extends only along a portion of the elongated tubular member 110, such as only along section 154, along sections 152 and 154, along sections 152, 154 and 148, along sections 152, 154, 148 and 146, along sections 152, 154, 148, 146 and 144, or along sections 152, 154, 148, 146, 144 and 142. Each possibility is a separate embodiment.

[0065] According to some embodiments, the braid 190 has a certain picks per inch (PPI) value to ensure a flexible distal end when combined with a low-hardness polymer and a relatively rigid proximal end when combined with a polymer having a higher hardness. According to some embodiments, the braided skeleton can have a wire arrangement of 75 - 150 picks per inch (PPI), 100 - 150 PPI or 100 - 150 PPI. Each possibility is a separate embodiment. As a non-limiting example, the braided skeleton can have a wire arrangement of about 140 PPI or about 145 PPI. Those skilled in the art will understand that the term "picks per inch (PPI)" is a measure of the braid wire density and represents the number of picks (e.g., weft threads) of the braid per inch.

[0066] As used herein, the terms "braid" and "braided skeleton" can refer to structural elements, such as tubular elements formed from multiple intertwined wires. According to some embodiments, the braid can be formed from at least three intertwined wires that form a tube. According to some embodiments, the braid can include from 8 to 48 wires or from 12 to 32 wires. As a non-limiting example, the braid can include 16 wires. Each possibility is a separate embodiment. According to some embodiments, the diameter of the wires forming the braid can be in the range of 10 - 60 microns, such as in the range of 15 - 40 microns or 20 - 30 microns, or any other suitable diameter within the range of 10 - 60 microns. Each possibility is a separate embodiment. As a non-limiting example, the wires forming the braid can have a diameter of 25 microns. According to some embodiments, the skeleton can extend along substantially the entire length of the conduit. According to some embodiments, the braid can be made of tungsten, stainless steel, nitinol (also known as Nitinol), nickel-titanium, cobalt-chromium, platinum-iridium, nylon, or any combination thereof. Each possibility is a separate embodiment.

[0067] According to some embodiments, at least some of the wires forming the braided skeleton can be braided in the same or opposite directions, i.e., left / right. Advantageously, the braided structure allows for good torque capabilities (superior to coiled skeletons), low flexural rigidity (i.e., good flexibility), good pushability (superior to coiled skeletons), and excellent kink resistance.

[0068] According to some embodiments, at least some of the wires forming the braided skeleton can be non-circular / non-round.

[0069] Below the braid 190 is a liner 192, which can be made of polytetrafluoroethylene (PTFE). According to some embodiments, the liner 192 can have a thickness of 10 - 30 microns or 10 - 25 microns. Each possibility is a separate embodiment. According to some embodiments, the liner can be a cast film liner.

[0070] Advantageously, to compensate for the bulky distal marker 162, the portion of the elongated tubular member 110 that extends from the distal end of the distal marker 162 to the distal opening 180 does not have the liner 192, thereby substantially maintaining the inner and outer diameters of the elongated tubular member 110 and enabling smooth delivery through a 5.0Fr delivery catheter (not shown) despite the bulkiness of the distal marker 162.

[0071] According to some embodiments, the total thickness of the wall at the distal end of the elongated tubular member does not exceed about 130 microns at least along the portion of the elongated tubular member to be inserted through a 5.0Fr delivery catheter. According to some embodiments, the total thickness of the wall at the distal end of the elongated tubular member does not exceed about 120 microns at least along the portion of the elongated tubular member to be inserted through a 5.0Fr delivery catheter.

[0072] Now referring to Figures 2A to 2C , which schematically illustrates an enlarged / exposed view of the embolization microcatheter 200 and portions thereof. The embolization microcatheter 200 may be similar to the embolization microcatheter 100, except that the embolization microcatheter 200 further includes a filter 220. Also referring to Figure 2D , which schematically illustrates the structure of the filter 220. The embolization microcatheter 200 is a 3.0Fr microcatheter having an elongate tubular member 210 with an outer diameter in the range of about 1.0 - 1.5 mm, or in the range of about 1.2 mm - 1.6 mm and an inner diameter in the range of 700 - 850 microns. The embolization microcatheter 200 is particularly suitable for delivering large embolization microspheres, such as but not limited to embolization microspheres having an average particle size of 500 microns or greater, 600 microns or greater, 700 microns or greater, 800 microns or greater, 900 microns or greater, and 1000 microns or greater. Each possibility is a separate embodiment.

[0073] The filter 220 includes a plurality of through-side openings formed in the wall of the elongate tubular member 210, as schematically illustrated in Figure 2B .

[0074] As used herein, the term "plurality" when combined with side openings refers to 2 or more, 3 or more, 5 or more, 10 or more, 15 or more, 20 or more, or 25 or more axial slits. Each possibility is a separate embodiment.

[0075] According to some embodiments, the filter 220 may be an integral part of the elongate tubular member 110 and may extend along a length of 0.3 mm to 20 mm, such as along 1 mm to 10 mm, 1 mm to 5 mm, 1.5 mm to 5 mm, 2 mm to 5 mm, or any other suitable length. Each possibility is a separate embodiment.

[0076] According to some embodiments, the total open area formed by the side openings of the filter 220 may be in the range of 0.2 - 1 mm 2 , 0.2 - 0.6 mm 2 , 0.3 - 1 mm 2 , 0.3 - 0.5 mm 2 , 0.4 - 0.6 mm 2 , 0.5 - 1.5 mm 2 , 1.0 - 3.5 mm 2 , 1.5 - 4 mm 2 , 2.0 - 3.5 mm 2 , or in the range of 0.1 - 4 mm 2Any other suitable area within the range. Each possibility is a separate embodiment. According to some embodiments, at least 5%, at least 10%, or at least 15% of the filter 220 is the open area formed by the side openings. According to some embodiments, 5%-30%, at least 7%-25%, 7%-20%, 5%-15% of the filter 220 is the open area formed by the side openings. Each possibility is a separate embodiment.

[0077] According to some embodiments, the side openings can be formed by selective cutting (e.g., selective laser cutting), i.e., without cutting the threads forming the fabric 290, as Figure 2D shown. According to some embodiments, the portion of the liner located below the threads remains intact. According to some embodiments, when the slit is formed, both the polymer layer and the liner between the threads of the fabric 290 are penetrated. Advantageously, the selective cutting of the polymer layer (leaving the fabric 290 substantially intact) can subdivide at least some of the side openings into two or more sub-side openings (here side openings 225a - 225d) that are separated by the fabric but not by the polymer outer layer.

[0078] Figure 3 An alternative structure of the filter 220 is provided. As Figure 3 seen, the filter 320 can include four filter sections 321, 322, 323, and 324, each filter section including a plurality of side openings 325, 326, 327, and 328 that are distributed in a circumferential circle around the filter 320.

[0079] According to some embodiments, the nearest filter section, i.e., filter section 321, has fewer side openings than the filter sections distal to it. According to some embodiments, filter section 321 can include 1 - 4 turns or 1 - 3 turns of side openings, such as but not limited to 2 turns of side openings. According to some embodiments, each turn can include 1 - 5 side openings or 1 - 3 side openings, such as but not limited to 2 side openings per turn. According to some embodiments, filter section 321 can include a total of 1 - 5 or 2 - 4 side openings, such as but not limited to 2 side openings.

[0080] According to some embodiments, the side openings of the nearest circumferential section are circumferentially offset relative to the side openings in its adjacent circumferential section.

[0081] According to some embodiments, the side openings 325 in the first turn of filter section 321 can be circumferentially offset relative to the side openings in its adjacent turn and / or relative to the side openings 326 of filter section 322.

[0082] According to some embodiments, the filtration section 322 may include 1-5 turns or 2-4 turns of side openings, such as but not limited to 3 turns of side openings. According to some embodiments, each turn may include 1-5 side openings or 2-4 side openings, such as but not limited to 3 side openings per turn. According to some embodiments, the filtration section 322 may include a total of 5-15 or 6-10 side openings, such as but not limited to 9 side openings.

[0083] According to some embodiments, the side openings 326 in the first turn of the filtration section 322 may be circumferentially offset relative to the side openings in its adjacent turns.

[0084] According to some embodiments, the filtration section 323 may include 2-10 turns or 3-7 turns of side openings, such as but not limited to 5 turns of side openings. According to some embodiments, each turn may include 2-15 side openings or 4-8 side openings, such as but not limited to 6 side openings per turn. According to some embodiments, the filtration section 323 may include a total of 10-50 or 20-40 side openings, such as but not limited to 30 side openings.

[0085] According to some embodiments, the side openings 325, 326, and 327 of the filtration sections 321, 322, and 323 may be axially slits that are substantially rectangular in shape. Due to the shape of the filter 220, the side openings 325, 326, and 327 may be conical, i.e., the cross-section of the outer surface of the filter 220 is larger than the cross-section of the inner surface.

[0086] The sizes provided below are related to the measurements made on the inner surface.

[0087] According to some embodiments, the dimensions of the side openings 325, 326, and 327 may be approximately 150×20 microns.

[0088] According to some embodiments, each turn of the side openings 325, 326, and 327 of the filtration sections 321, 322, and 323 may be spaced 100-200 microns or 120-180 microns from its adjacent turn, such as but not limited to 150 microns.

[0089] According to some embodiments, the farthest filtration section, i.e., the filtration section 324, is positioned proximally about 2-5 mm from the distal opening. According to some embodiments, the farthest filtration section, i.e., the filtration section 324, is positioned proximally about 3 mm from the distal opening.

[0090] According to some embodiments, the side openings 328 of the filtration section 324 are substantially square. Advantageously, the square size of the side openings 328 allows fluid to flow out while ensuring minimal interference with the flow of microspheres towards the distal opening, even though the microspheres have become concentrated due to the outflow of fluid through the side openings 325, 326, and 327. According to some embodiments, the filtration section 324 may include 3 - 10 turns or 4 - 6 turns of side openings, such as but not limited to 5 turns of side openings. According to some embodiments, each turn may include 3 - 10 side openings or 4 - 8 side openings, such as but not limited to 6 side openings per turn.

[0091] According to some embodiments, the side openings 328 of the filtration section 324 may have dimensions of approximately 50×50 microns.

[0092] According to some embodiments, the side openings 328 of the furthest turn may be spaced 1 - 10 mm or 2 - 7 mm, such as but not limited to 2 mm, from the furthest turn of these side openings 327 in the filtration section 323.

[0093] According to some embodiments, the side openings 328 of the furthest turn may be spaced 1 - 10 mm or 2 - 5 mm, such as but not limited to approximately 3 mm, from the distal opening.

[0094] According to some embodiments, each turn of the side openings 328 of the filtration section 324 may be spaced 20 - 100 microns or 30 - 60 microns, such as but not limited to 50 microns, from its adjacent turn.

[0095] According to some embodiments, the slits may be positioned at the same or different longitudinal positions. Each possibility is a separate embodiment. According to some embodiments, the distribution of the slits may be staggered, zigzag, or any other suitable uniform or non - uniform distribution.

[0096] Advantageously, the filter 320 may still be configured for kink - free bending despite having multiple slits formed in its walls. According to some embodiments, the flexibility of the filter 320 is determined by the number of side openings, the minimum cross - sectional size of the side openings, the width of the side openings, the length spacing, the geometry, the distance from the distal outlet, etc. (as generally described herein), and its kink - free bending can be achieved.

[0097] As used herein, the term "kink - free bending" may refer to bending that does not actually impede the flow through the filter 320. According to some embodiments, the filter 320 may be configured for kink - free bending at an angle of approximately 180 degrees. According to some embodiments, the filter 320 may be configured for kink - free bending with a minimum bending radius that ranges from about 0.5 mm to 1.5 mm, such as 0.5 mm to 1.2 mm, 0.5 mm to 1 mm, or any radius therebetween.

[0098] Advantageously, the microcatheter 300 including the filter 320 effectively prevents backflow, which requires a relatively high side opening density while still ensuring a small kink-free radius (e.g., in the range of 0.5 mm to 1.5 mm) and a tensile strength of at least 5 N.

[0099] According to some embodiments, the length of the microcatheter 300 can be at least 50 cm, at least 60 cm, at least 75 cm, or at least 1 m. Each possibility is a separate embodiment.

[0100] According to some embodiments, the outer wall of the microcatheter 300 can be non-tapered substantially along its / their entire length.

[0101] Figure 4 An alternative structure of the filter 220 is provided in. As Figure 4 As seen in, the filter 420 can include two filter sections 421 and 422, each filter section including a plurality of side openings 425 and 427 that are circumferentially distributed around the elongated tubular filter 420.

[0102] Due to the shape of the filter 420, the side openings 425 and the side openings 427 can be conical, i.e., the cross-section of the outer surface of the filter 220 is larger than the cross-section of the inner surface.

[0103] The sizes provided below are related to the measurements taken on the inner surface.

[0104] According to some embodiments, the filter section 421 can include 2 - 10 loops or 2 - 6 loops of side openings, such as but not limited to 5 loops of side openings. According to some embodiments, each loop can include 1 - 10 side openings or 2 - 8 side openings, such as but not limited to 6 side openings per loop. According to some embodiments, the filter section 421 can include a total of 10 - 60 side openings or 20 - 40 side openings, such as but not limited to 30 side openings. According to some embodiments, the side openings 425 can be substantially square or rectangular. According to some embodiments, the side openings 425 can have a width of 50 - 150 microns or 50 - 100 microns, e.g., a width of about 80 microns. According to some embodiments, the side openings 425 can have a length of 20 - 100 microns, or e.g., a length of about 50 microns. According to some embodiments, each loop of side openings can be longitudinally spaced from its adjacent loop by 20 - 100 microns or e.g., approximately 50 microns. According to some embodiments, the farthest side opening 425 can be positioned at a distance of about 2 - 5 mm, e.g., about 3 mm, from the distal opening of the microcatheter.

[0105] Advantageously, the square size of the side openings 425 allows fluid to flow out while ensuring minimal interference with the flow of microspheres towards the distal opening, even though the microspheres have become concentrated due to the outflow of fluid through the side openings 325, 326, and 327.

[0106] According to some embodiments, the filtration section 422 may include 5 - 50 or 10 - 30 or 10 - 20 side openings 427. According to some embodiments, the width of the side openings 427 may be in the range of 10 - 50 microns or 10 - 30 microns, such as about 20 microns. According to some embodiments, at least some of the side openings 427 may have different lengths. According to some embodiments, at least some of the side openings 427, such as side opening 427a, may have a length in the range of about 1 mm - 4 mm or about 2 mm - 3.5 mm (e.g., about 2.7 mm). According to some embodiments, at least some of the side openings 427, such as side opening 427b, may have a length in the range of about 0.8 mm - 2 mm or about 1 mm - 1.5 mm (e.g., about 1.35 mm). According to some embodiments, at least some of the side openings 427, such as side opening 427c, may have a length in the range of about 0.2 mm - 1 mm or about 0.2 mm - 0.5 mm (e.g., about 0.3 mm). Advantageously, the filter 220 can be formed by selectively cutting the polymer layer (leaving the braid 290 intact). According to some embodiments, at least some of the side openings 427 may include sub - side openings separated by the braid 290 rather than by the polymer outer layer ( Figure 2D illustrated in the figure as having members 225a - 225d).

[0107] According to some embodiments, each side opening 427 is longitudinally spaced 20 - 200 microns from an adjacent side opening. According to some embodiments, the longitudinal spacing between the side openings 427 may be different. According to some embodiments, at least some of the side openings 427 are axially offset relative to adjacent side openings. According to some embodiments, the farthest side opening 427 may be positioned about 3 - 10 mm, such as about 5 mm, from the distal opening of the microcatheter.

[0108] According to some embodiments, the filter 420 may have a length of 5 - 15 mm or about 5 - 10 mm.

[0109] According to some embodiments, the slits may be located at the same or different longitudinal positions. Each possibility is a separate embodiment. According to some embodiments, the distribution of the slits may be staggered, zig - zag, or any other suitable uniform or non - uniform distribution.

[0110] Advantageously, although multiple slits are formed in its wall, the filter 420 can still be configured for kink-free bending. According to some embodiments, the flexibility of the filter 220 is determined by the number of side openings, the minimum cross-sectional size of the side openings, the width of the side openings, the length interval, the geometry, the distance from the distal outlet, etc. (as substantially described herein), and its kink-free bending can be achieved.

[0111] As used herein, the term "kink-free bending" may refer to bending that actually impedes the filter 420 through which fluid flows. According to some embodiments, the filter 420 can be configured for kink-free bending at an angle of approximately 180 degrees. According to some embodiments, the filter 420 can be configured for kink-free bending with a minimum bending radius, and the minimum bending radius is in the range of about 0.5 mm to 1.5 mm, such as 0.5 mm to 1.2 mm, 0.5 mm to 1 mm, or any radius therebetween.

[0112] Advantageously, the microcatheter 400 including the filter 420 effectively prevents backflow, which requires a relatively high side opening density while still ensuring a small kink-free radius (e.g., in the range of 0.5 mm to 1.5 mm) and a tensile strength of at least 5 N.

[0113] According to some embodiments, the length of the microcatheter 400 can be at least 50 cm, at least 60 cm, at least 75 cm, or at least 1 m. Each possibility is a separate embodiment. Each possibility is a separate embodiment.

[0114] According to some embodiments, the outer wall of the microcatheter 400 can be non-tapered substantially along its / their entire length.

[0115] As used herein, the terms "approximately" and "about" refer to + / - 10%, or + / - 5%, or +- 2% relative to the range they refer to. Each possibility is a separate embodiment.

[0116] Although many exemplary aspects and embodiments have been discussed above, certain modifications, additions, and sub-combinations thereof will be envisioned by those skilled in the art. Accordingly, the appended claims and the claims introduced hereinafter are intended to be construed to include all such modifications, additions, and sub-combinations within their true spirit and scope.

Claims

1. An embolization microcatheter, comprising: An elongate tubular member forming a lumen, the elongate tubular member terminating in a distal opening, wherein the wall of the elongate tubular member comprises a braid, a polymer formed around the braid, and a lining covering the inner surface of the wall; Wherein the wall of the portion of the elongate tubular member extending between the proximal radiopaque marker and the distal opening has a thickness less than or equal to 130 microns; A distal radiopaque marker located near the distal opening; And A filter formed in the wall of the elongate tubular member, the filter comprising two or more filter segments, each filter segment comprising a plurality of side openings penetrating the wall, the plurality of side openings being circumferentially distributed around the elongate tubular member; the proximalmost side openings included in the filter segment are fewer than the side openings in the distal loops thereof; the shape and size of the side openings vary between the proximal and distal ends of the filter; Wherein the portion of the elongate tubular member extending between the proximal end of the distal radiopaque marker and the distal opening has no lining.

2. The embolization microcatheter according to claim 1, wherein, The outer diameter of the elongate tubular member is less than or equal to 1.5 mm, and the inner diameter of the elongate tubular member is 700 microns or greater.

3. The embolization microcatheter according to claim 1 or 2, wherein the thickness of the distal end of the wall is less than or equal to 120 microns.

4. The embolization microcatheter according to claim 1, wherein, The distalmost side of the filter segment is positioned proximally 2 - 4 mm from the distal opening.

5. The embolization microcatheter according to claim 1, wherein, The side openings of the distalmost filter segment are square.

6. The embolization microcatheter according to claim 5, wherein, The size of the square side openings is 50×50 microns.

7. The embolization microcatheter according to claim 5, wherein, The size of the square side openings is 80×50 microns.

8. The embolization microcatheter according to claim 5, wherein, The side openings of the remaining filter segments of at least two filter segments are in the form of axial slits.

9. The embolization microcatheter according to claim 8, wherein The side openings of the remaining filter segments of at least two filter segments have a width of 20 microns, wherein the lengths of the side openings of the remaining filter segments of at least two filter segments differ between these side openings.

10. The embolization microcatheter according to claim 9, wherein, The side openings of the remaining filter segments of at least two filter segments have a length of at least 200 microns.

11. The embolization microcatheter according to any one of claims 8 to 10, wherein At least some of the side openings of the remaining filter segments of at least two filter segments have a size of 2700×20 microns.

12. The embolization microcatheter according to any one of claims 8 to 10, wherein, At least some of the side openings of the remaining filter segments of at least two filter segments have a size of 1350×20 microns.

13. The embolization microcatheter according to any one of claims 8 to 10, wherein, At least some of the side openings of the remaining filter segments of at least two filter segments have a size of 300×20 microns.

14. The embolization microcatheter according to claim 1 or 2, wherein, The braid is made of tungsten.

15. The embolization microcatheter according to claim 1 or 2, wherein The lining comprises polytetrafluoroethylene.

16. The embolization microcatheter according to claim 1 or 2, wherein The radiopaque markers comprise metal marker bands.

17. The embolization microcatheter according to claim 1 or 2, wherein The distal radiopaque marker is positioned proximally 0.5 - 2 mm from the distal opening.

18. The embolization microcatheter according to claim 1 or 2, the embolization microcatheter being suitable for delivering embolization microspheres with a particle size of 900 microns.

19. The embolization microcatheter according to claim 1 or 2, having a length of at least 1 m.

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