Microcatheters for interventional cardiovascular and / or neurovascular applications

Abstract

The microcatheter (1) having a distal tip (15) includes a tubular catheter wall (2) with a proximal section (6) and a distal section (14). The catheter wall includes a scaffold, an inner liner, and an outer laminate. A continuous scaffold extent is defined extending distally from at least a first location (21) to the distal tip (15). Throughout the continuous scaffold extent, the scaffold extends continuously to form at least one elongated, continuous reinforcing structure. Two total scaffold cutout ratios for all portions of the distal section and all portions of the distal tip within the continuous scaffold extent are at least 50% and at least 20%, respectively. The present invention provides a solution that optimizes catheter flexibility when navigating deep within very fine, tortuous vascular pathways while simultaneously enabling the microcatheter to penetrate and pass through highly constricted stenoses.

Description

[Technical Field]

[0001] The present invention relates to a catheter, which is a microcatheter for interventional cardiovascular and / or neurovascular applications, the catheter comprising a tubular catheter wall surrounding a luminal structure of the catheter, the catheter wall having a proximal end, a distal end and a longitudinal direction extending from the proximal end to the distal end, the catheter wall having a length of at least 1000 mm along the longitudinal direction from the proximal end to the distal end. [Background technology]

[0002] In such cardiovascular and neurovascular applications, such catheters must be angled through the tortuous bends and curves of vascular pathways to reach targeted anatomical structures. Such catheters require sufficient flexibility, particularly near their distal ends, to navigate such tortuous paths. However, other design aspects must also be considered. For example, the catheter must also be able to provide sufficient torqueability (i.e., the ability to transmit a torque applied at the proximal end to the distal end), pushability (i.e., the ability to transmit an axial push to the distal end), and structural integrity to perform its intended medical function.

[0003] US2019 / 0255290A1 discloses an example of an interventional cardiovascular catheter specifically designed for positioning near the aortic root in Figure 3. Figures 4A-4D and 5 of US2019 / 0255290A1 show several examples of scaffolds that can be applied to various longitudinal sections of the catheter of Figure 3 of US2019 / 0255290A1. Such scaffolds are interrupted tubular reinforcement walls obtained by micromachining a cut pattern into a completely uninterrupted tubular reinforcement wall made from a reinforcement material. The catheter of Figure 3 of US2019 / 0255290A1 is specifically designed to provide a relatively sharp bend 54 (see Figure 2 of US2019 / 0255290A1) for extending across the aortic root 16 to reach the artery 24 (see Figure 2 of US2019 / 0255290A1). In particular, the proximal-medial section 106 of US2019 / 0255290A1 FIG. 3, which includes the single beam configuration of the skeleton of US2019 / 0255290A1 FIG. 4D, is designed to provide this relatively sharp bend 54. US2019 / 0255290A1 further discloses that the catheter of US2019 / 0255290A1 FIG. 3 can have an inner liner and / or outer laminate that extend distally beyond the skeleton to form the atraumatic distal tip 116 of the catheter.

[0004] Compared with the specific design objectives mentioned above underlying the catheter of the above-mentioned document US2019 / 0255290A1, the present invention has different objectives, which are summarized as follows: Summary of the Invention

[0005] The object of the present invention is to provide a solution for optimizing the flexibility of a microcatheter while navigating deep within very fine and tortuous cardiovascular and neurovascular pathways, while at the same time allowing the microcatheter to penetrate and pass through highly congested stenoses.

[0006] To that end, the present invention provides a catheter as set forth in the attached independent claim 1. Preferred embodiments of the invention are provided by the attached dependent claims 2-7.

[0007] The present invention therefore provides a catheter, which is a microcatheter for interventional cardiovascular and / or interventional neurovascular applications, comprising: The catheter comprises a tubular catheter wall surrounding a luminal structure of the catheter, the catheter wall having a proximal end, a distal end, and a longitudinal direction extending from the proximal end to the distal end, the catheter wall having a length of at least 1000 mm along the longitudinal direction from the proximal end to the distal end; The catheter wall a proximal section defined to extend longitudinally distally from the proximal end to a first location 100 mm proximal from the distal end; a distal section defined to extend distally along a longitudinal direction from the first location to a distal end; a distal tip of the catheter, the distal section being defined to extend proximally along a longitudinal direction from the distal end to a second position 7 mm proximal to the distal end; The catheter wall, at least in a portion of the distal section, a scaffold that provides reinforcement for the catheter wall not only in the longitudinal direction but also in the circumferential direction about the longitudinal direction, the scaffold being an interrupted tubular reinforcing wall obtained by micromachining a cut pattern into an entirely uninterrupted tubular reinforcing wall made from a reinforcing material, the reinforcing material of the scaffold extending continuously throughout a continuous scaffold extent along the longitudinal direction to form at least one elongated continuous reinforcing structure along the entire continuous scaffold extent, the continuous scaffold extent extending distally along the longitudinal direction from a first location to a location 2 mm proximal to the distal end; an inner liner coaxially surrounded by the skeleton relative to the centerline of the catheter wall, at least in the continuous skeleton area; an outer laminate coaxially surrounding the scaffold relative to a centerline of the catheter wall, at least in the continuous scaffold area; The total skeletal cutout ratio of the longitudinal section of the catheter wall in the longitudinal extent along the longitudinal direction is: - of the volume of all portions within the longitudinal extent of the reinforcing material that are cut from the completely uninterrupted tubular reinforcing wall according to the micro-machined cut pattern; - defined as a percentage of the volume of the completely uninterrupted tubular reinforcing wall relative to the volume of all portions of the reinforcing material within the longitudinal extent, the total skeletal resection ratio of all parts of the distal section within the continuous skeletal range is at least 50%; A catheter is provided in which the total skeletal cutout ratio of all portions of the distal tip within the continuous skeletal range is at least 20%.

[0008] In the above aspect of the invention, the main features of the invention are: i. the skeletal reinforcing material extends continuously along at least the continuous skeletal extent extending distally from the first location 100 mm proximal to the distal end to a location 2 mm proximal to the distal end to form at least one elongated continuous reinforcing structure along the entire continuous skeletal extent; ii. The total skeletal resection ratio for all parts of the distal section within the contiguous skeletal range is at least 50%; and iii. The total skeleton cutout ratio for all portions of the distal tip within the continuous skeleton is at least 20%.

[0009] Thanks to these combined key features (i), (ii), and (iii), the microcatheter according to the present invention has good flexibility in the distal section, including the distal tip. It should be noted that the distal tip of a microcatheter typically has a length of 3 to 7 mm, with exceptions where the distal tip is longer, up to 8 or 9 mm. In particular, the flexibility of the distal tip is crucial for continuously advancing the microcatheter through the tortuous bends and curves of the vascular passageway to reach the targeted anatomical structure. After all, once the distal tip has passed through the difficult curve, the rest of the microcatheter generally follows suit. Furthermore, the distal tip of the microcatheter must often penetrate and pass through highly constricted stenoses. For this purpose, the distal tip must also have good penetration behavior and structural strength. According to main feature (i), the fact that the backbone of the catheter according to the invention extends continuously from said first position 100 mm proximal from the distal end to a position extending 2 mm proximal from the distal end provides the distal tip with good penetration behavior and structural strength to successfully penetrate and pass through highly clogged stenoses. Main features (ii) and (iii) in combination with main feature (i) further provide the distal section and distal tip with flexibility properties to successfully navigate the microcatheter through difficult tortuous bends and curves in vasculature passages.

[0010] On the other hand, known distal tips of microcatheters are either atraumatic tips with no (metallic) reinforcing material at all, or distal tips with a completely uninterrupted tubular metallic reinforcing wall. Known atraumatic distal tips are generally unsuitable for penetrating and passing through highly constricted stenoses in the vasculature, while known uninterrupted metallic distal tips are generally unsuitable for passing through the difficult, tortuous bends and curves in the vasculature. It should be further noted that the most serious problem with known uninterrupted metallic distal tips fixed to a catheter is that such distal tips may be severed from the catheter during an interventional procedure. On the other hand, the distal tip of the microcatheter according to the present invention has very good structural integrity with the remainder of the distal section of the catheter, since the skeletal reinforcing material extends continuously distally from said first position, at least 100 mm proximal to the distal end, to a position 2 mm proximal to the distal end.

[0011] It should be noted that producing such a high total skeleton cutout ratio (at least 50%) of the distal section according to the present invention requires the inventive measures to solve several problems in the present case, where the catheter in question is a microcatheter for interventional cardiovascular and / or interventional neurovascular applications, having the inner liner surrounded by the skeleton. This is because the inner liner for such cardiovascular and / or neurovascular applications is typically a tube made of, for example, PTFE (polytetrafluoroethylene, e.g., Teflon®), PVDF (polyvinylidene fluoride, e.g., Kynar®), or HDPE (high-density polyethylene), which is inserted axially into the skeleton during the manufacture of the microcatheter and then expanded relative to the skeleton by inflation and heat. Such a high cutout ratio can cause problems, for example, in that the tube made of PTFE, PVDF, or HDPE, which expands relative to the skeleton, protrudes from the large cutout in the skeleton material and / or breaks under the inflation pressure. Another problem, especially with scaffolds made from weaker materials, is that the scaffolds can significantly deform and / or crack and / or break under inflation pressure due to the fact that they are significantly weakened by large cutouts in the scaffold material.

[0012] In that regard, the present invention is based, inter alia, on the novel insight that, as disclosed herein, the problem can be solved by temporarily introducing a heat-shrinkable outer tube on the outside of the scaffold during the manufacture of a catheter according to the present invention, the heat-shrinkable outer tube temporarily closing the cutouts in the scaffold material during said expansion of the inner liner by inflation and heat, and at the same time, the heat-shrinkable outer tube temporarily reinforcing the scaffold during said expansion of the inner liner by inflation and heat. After the inner liner has been successfully expanded against the scaffold, and after the catheter under construction has cooled, the temporary heat-shrinkable outer tube can be removed from the outside of the scaffold and replaced with the final outer laminate on the outside of the scaffold.

[0013] Alternatively, as disclosed herein, another novel insight is that in the case of such a very high total skeleton cutout ratio (at least 50%) of the distal section of the catheter wall of a catheter according to the present invention, the problem can be solved by performing the following manufacturing steps to assemble the inner liner and outer laminate onto the skeleton: First, a tubular base layer of fluorinated ethylene propylene (FEP) is extruded, and the inner liner is extruded onto the base layer. Next, the FEP base layer together with the inner liner is inserted axially into the skeleton. Next, the outer laminate is slid onto the outside of the skeleton. After that, a temporary heat-shrinkable outer FEP tube is slid onto the outer laminate, and the entire assembly is heated. During heating, the temporary heat-shrinkable outer FEP tube provides high compression to the assembly of the inner liner, skeleton, and outer laminate. After the catheter under construction has cooled, the temporary heat-shrinkable outer tube can be removed from the outside of the skeleton, and the FEP base layer can be pulled axially out of the assembly, taking advantage of FEP's favorable properties with respect to pulling. Thus, a very close fit of the inner liner to the inside of the skeleton is obtained.

[0014] Another advantage of the present invention is that, thanks to the very high total skeleton cut-out ratio (at least 50%) of the distal portion of the catheter wall of a catheter according to the present invention, and thanks to the above-mentioned insights disclosed herein, the present invention allows for efficient embedding of radiopaque elements (e.g., radiopaque markers) in the catheter wall, since the radiopaque elements can be perfectly positioned in the spaces of the cut pattern, which spaces are bounded by the skeleton, the inner layer, and the outer laminate.

[0015] In a preferred embodiment of a catheter according to the invention, the continuous scaffolding extends distally along the length from the first location to at least a location 0.5 mm proximal to the distal end, so that the scaffolding extends further distally to the distal tip, which further promotes good penetration behavior of the distal tip to successfully pass through highly congested stenoses.

[0016] More preferably, the continuous scaffolding extends distally along the length from the first location to at least a location 0.2 mm proximal to the distal end, so that the scaffolding extends distally to the distal tip and even further, which further promotes good penetration behavior of the distal tip to successfully pass through highly congested stenoses.

[0017] In another preferred embodiment of the catheter according to the present invention, the total skeletal cut-out ratio of all portions of the distal section within the continuous skeletal range is at least 65%, and the total skeletal cut-out ratio of all portions of the distal tip within the continuous skeletal range is at least 40%, which promotes greater flexibility in the distal section and distal tip, which further aids in continuously navigating the microcatheter through tortuous bends and curves in vasculature passageways to reach targeted anatomical structures.

[0018] More preferably, the total skeletal cutout ratio of all portions of the distal section within the continuous skeletal range is at least 80%, and the total skeletal cutout ratio of all portions of the distal tip within the continuous skeletal range is at least 60%, which promotes even greater flexibility in the distal section and distal tip, which further aids in continuously navigating the microcatheter through tortuous bends and curves in vasculature passageways to reach targeted anatomical structures.

[0019] In another preferred embodiment of a catheter according to the present invention, the radiopaque elements are embedded in the catheter wall in that they are located in the spaces of the cut pattern, and the spaces are bounded by the backbone, the inner layer, and the outer laminate.

[0020] In another preferred embodiment of a catheter according to the invention, the skeleton has a distal longitudinal skeleton end in the form of a circular edge of the skeleton, the circular edge having a center point on the centerline of the catheter wall. Such a distal skeleton end in the form of a circular edge of the skeleton further promotes good penetration behavior of the distal tip to successfully pass through highly congested stenoses while improving the structural integrity of the skeleton and still allowing good flexibility of the distal tip.

[0021] In another preferred embodiment of a catheter according to the present invention, the distal tip is a tapered distal tip in that the distal tip has an outer diameter that gradually narrows distally along the longitudinal direction to the distal end. Such a tapered distal tip further promotes good penetration behavior of the distal tip. The tapering of the tapered distal tip may be oriented, by way of example only, at an angle of approximately 5 degrees relative to the centerline of the catheter wall. The tapering of the tapered distal tip may be fabricated, for example, after the inner liner and outer laminate of the catheter wall are assembled to the distal tip skeletal reinforcing material. However, alternatively, the tapering of the tapered distal tip may be fabricated before the inner liner and / or outer laminate of the catheter wall are assembled to the distal tip skeletal reinforcing material.

[0022] In the following, the invention will be further elucidated with reference to non-limiting embodiments and with reference to the schematic diagrams of the accompanying drawings in which the following is shown: [Brief explanation of the drawings]

[0023] [Figure 1] 1 shows an example of an embodiment of a catheter according to the present invention in a longitudinal side view, in which the proximal and distal sections of the catheter wall and the distal tip of the catheter are indicated by brace marks. [Figure 2A] 2 illustrates a short longitudinal section of the catheter wall of the catheter of FIG. 1 within the continuous skeletal range described above, where the longitudinal section illustrated comprises a portion of the catheter wall skeleton and the view illustrated is a longitudinal cross-section including the centerline of the catheter wall. [Figure 2B]2B shows a cross section through a longitudinal section of the catheter wall of FIG. 2A, the cross section shown being perpendicular to the centerline. [Figure 3] 1 shows the catheter embodiment of FIG. 1 again, showing the same longitudinal side view of FIG. 1, but this time with first, second, third, fourth, and fifth longitudinal subsections of the catheter wall indicated by brace marks, the first, second, third, fourth, and fifth subsections of the catheter wall having first, second, third, fourth, and fifth skeletal structures of the catheter wall skeleton, respectively, and the first, second, third, fourth, and fifth skeletal structures each having a different structural type from one another. [Figures 4A-4C] 4 shows a detail of a first skeletal structure of a first subsection of the catheter wall of the catheter of FIG. 3. [Figures 5A-5D] 4 shows a detail of a second skeletal structure of a second subsection of the catheter wall of the catheter of FIG. 3. [Figures 6A-6B] 4 shows a detail of a third skeletal structure of a third subsection of the catheter wall of the catheter of FIG. 3. [Figures 7A-7E] 4 shows a detail of a fourth skeletal structure of a fourth subsection of the catheter wall of the catheter of FIG. 3. [Figures 8A-8C] 10 shows a detail of a fifth skeletal structure of a fifth subsection of the catheter wall of the catheter of FIG. 3.

[0024] The reference symbols used in Figures 1-8 refer to the above-mentioned and related parts and aspects of the present invention as follows: 1-------------catheter 2-------------Tubular catheter wall 3-------------Lumen structure 4-------------proximal end 5-------------distal end 6-------------Proximal division 7-------------Skeleton 7A------------Cutting pattern 8-------------Inner liner 9-------------Outer laminate 10------------Longitudinal direction 11------------Circumferential direction 12------------Center line 14------------distal division 15------------distal tip 16------------distal skeletal end 21------------First position 22------------Second position 31------------First subsection of catheter wall 2 32------------Second subsection of catheter wall 2 33------------Third subdivision of catheter wall 2 34------------Fourth subdivision of catheter wall 2 35------------5th subdivision of catheter wall 2 41------------First skeletal structure 42------------Second skeletal structure 43------------Third skeletal structure 44------------Fourth skeletal structure 45------------Fifth skeletal structure 51~54---------Spiral part 61~66---------Spiral slot

[0025] Based on the introductory discussion above, including a brief description of the drawings, and based on the above-listed reference numerals used in Figures 1-8, the embodiments of Figures 1-8 are, for the most part, readily self-evident. Additional explanation is provided below.

[0026] 1 shows the proximal section 6 and the distal section 14 of a catheter 1 according to the present invention. FIG. 1 further shows that the distal section 14 includes a distal tip 15.

[0027] 2A-2B, it can be seen that the catheter wall 2 of the catheter 1 of FIG. 1 has a framework 7 that includes a cut pattern 7A. It can also be seen that the catheter wall 2 has an inner liner 8 and an outer laminate 9. In the example of FIGS. 2A-2B, the lumen structure 3 of the catheter 1 is a single lumen structure. Alternatively, a catheter according to the present invention can have multiple lumen structures.

[0028] In the example shown in Figures 1-8, the skeleton 7, inner liner 8, and outer laminate 9 of the catheter wall 2 of the catheter 1 are present along the entire longitudinal direction 10 of the catheter wall 2 from the proximal end 4 to the distal end 5. Furthermore, in the example shown in Figures 1-8, the continuous skeleton area extends the entire catheter wall 2 from the proximal end 4 to the distal end 5, where the skeleton extends continuously to form at least one elongated continuous reinforcing structure along the entire continuous skeleton area. However, alternatively, for a catheter according to the present invention, the continuous skeleton area does not necessarily extend the entire catheter wall from the proximal end to the distal end of the catheter, and the skeleton, inner liner, and outer laminate of a catheter according to the present invention do not necessarily have to be present the entire catheter wall from the proximal end to the distal end, as long as the skeleton, inner liner, and outer laminate are at least present in the continuous skeleton area in the manner specified in accordance with the present invention in the introduction to this disclosure above. Thus, for a catheter according to the present invention, the continuous skeletal extent may be limited to extending distally along the longitudinal direction from the first location 21 to a location 2 mm proximal to the distal end, for example.

[0029] FIG. 3 shows a first subsection 31, a second subsection 32, a third subsection 33, a fourth subsection 34, and a fifth subsection 35 of the catheter wall 2, each having a first skeletal structure 41, a second skeletal structure 42, a third skeletal structure 43, a fourth skeletal structure 44, and a fifth skeletal structure 45, which are shown in more detail in FIGS. 4-8, respectively.

[0030] The five skeletal structures 41 - 45 are interconnected in a continuous end-to-end manner along the longitudinal direction 10 to form strings that form the skeleton 7 of the catheter wall 2 of the catheter 1 .

[0031] It should be noted that in the example shown, the outer and inner diameters of the catheter wall 2 are 0.635 mm and 0.510 mm, respectively, throughout the entire longitudinal extent 10 of the catheter wall 2 from the proximal end 4 to the distal end 5. However, for catheters according to the present invention, alternatively, neither the outer nor inner diameter of the catheter wall 2 need be constant throughout the entire longitudinal extent of the catheter wall from the proximal end to the distal end. For example, as discussed above, the distal tip 15 can be a tapered distal tip in that the distal tip has an outer diameter that gradually narrows distally along the longitudinal extent to the distal tip 5.

[0032] It should further be noted that if the distal tip 15 is a tapered distal tip, and if the radiopaque elements are embedded in the catheter wall in that they are located in the spaces of the cut pattern 7A, then the embodiments of Figures 1-8 are embodiments of catheters according to all of the preferred embodiments of the present invention mentioned above in the introduction to this disclosure.

[0033] Reference is now made to Figures 4A-4C, which show the first skeletal structure 41 of the scaffold 7. Figure 4A is a longitudinal side view of the first skeletal structure 41 along the entire extent of the first subsection 31 along the longitudinal direction 10, corresponding to a length of 6.9 mm as shown in Figure 3. Figure 4B is an enlarged detail of the boxed area on the left side of Figure 4A. In Figure 4B, some dimensions are indicated numerically and should be interpreted in millimeters (mm). Figure 4C is a perspective view of the first skeletal structure 41. In Figures 4A-4C, the first skeletal structure 41 consists of nine parallel rings interconnected laterally by pairs of longitudinal helical segments. Figures 4A-4C further show distal skeletal ends 16 in the form of circular edges of the end rings of the nine rings of the first skeletal structure 41. This distal scaffold end 16 in the form of a rounded edge of the scaffold 7 promotes good penetration behavior of the distal tip 15 to successfully pass through highly clogged stenoses while improving the structural integrity of the scaffold 7 and still allowing good flexibility of the distal tip 15.

[0034] Reference is now made to Figures 5A-5D, which illustrate the second skeletal structure 42 of the skeleton 7. The second skeletal structure 42 extends in the second subsection 32 along the longitudinal direction 10 over a length of 16.8-6.9 mm = 9.9 mm as shown in Figure 3. Each of Figures 5A-5D shows the second skeletal structure 42 along only a portion of its length, as described below. Figure 5A shows a portion of the second skeletal structure 42 in a longitudinal side view. Figure 5B is an enlarged detail of the boxed area on the left side of Figure 5A. Figure 5C shows a top view of a longitudinal section of the second skeletal structure 42 in a hypothetical "unrolled tube" state of the longitudinal section. To explain the term "unrolled tube," it should be noted that the skeleton according to the present invention is a tubular wall (more specifically, an intermittent tubular reinforcement wall) that can be virtually unfolded into a perfectly straight state by making a virtual straight cut parallel to the centerline along the entire length of the tubular wall and then virtually unfolding it onto a perfectly straight plane. In Figures 5B and 5C, some dimensions are given numerically and should be interpreted in millimeters (mm). Figure 5D is a perspective view of a portion of the second skeleton structure 42 shown in Figure 5A.

[0035] Reference is now made to FIGS. 6A-6B, which illustrate the third skeletal structure 43 of the skeleton 7. The third skeletal structure 43 extends in the third subsection 33 along the longitudinal direction 10 over a length of 81.9-16.8 mm = 65.1 mm as shown in FIG. 3. Each of FIGS. 6A-6B shows the third skeletal structure 43 along only a portion of its length, as described below. FIG. 6A shows a portion of the third skeletal structure 43 in a longitudinal side view. FIG. 6B is a perspective view of a portion of the third skeletal structure 43. FIGS. 6A-6B show that the third skeletal structure 43 of the skeleton 7 consists of parallel rings interconnected laterally in the axial direction by pairs of diametrically opposed spring-like connecting beams, with each successive pair of longitudinally extending beams positioned at a 45-degree offset angle relative to each other in the circumferential direction about the longitudinal direction. In FIG. 6A, the thickness of one of the parallel rings is indicated by the number 0.10, which should be interpreted in millimeters (mm).

[0036] Reference is now made to Figures 7A-7E, which illustrate the fourth skeletal structure 44 of the skeleton 7. The fourth skeletal structure 44 extends in the fourth subsection 34 along the longitudinal direction 10 over a length of 453.9-81.9 mm = 372.0 mm as shown in Figure 3. Each of Figures 7A-7E shows the fourth skeletal structure 44 along only a portion of its length, as described below. Figure 7A shows a portion of the fourth skeletal structure 44 in a longitudinal side view. Figures 7B and 7C show two other portions of the fourth skeletal structure 44 in a longitudinal side view, with the portion in Figure 7B located distal to the portion in Figure 7A and the portion in Figure 7C located proximal to the portion in Figure 7A. Figure 7D is a perspective view of the fourth skeletal structure 44. 7E shows a top view of a longitudinal section of the fourth skeletal structure 44 in a hypothetical unrolled tube state of the longitudinal section (the term "unrolled tube" is explained above with reference to FIG. 5C). Figures 7D-7E show that the fourth skeletal structure 44 of the skeleton 7 consists of four helical portions, two of which are right-handed helical portions 51, 52 and two of which are left-handed helical portions 53, 54, with the two right-handed helical portions 51, 52 intersecting with the two left-handed helical portions 53, 54 at multiple nodes of the fourth skeletal structure 44.

[0037] 7B and 7C, some dimensions are indicated numerically and should be interpreted in millimeters (mm). Figures 7B and 7C serve to illustrate the manner in which the thickness of the helical portion of the fourth skeletal structure 44 gradually decreases distally along the longitudinal direction 10, thereby gradually increasing the flexibility of the fourth subsection 34 of the catheter wall 2 distally along the longitudinal direction 10.

[0038] Reference is now made to Figures 8A-8C, which show the fifth skeletal structure 45 of the scaffold 7 in longitudinal side view. The fifth skeletal structure 45 extends in the fifth subsection 35 along the longitudinal direction 10 over a length of 1443.5-453.9 mm = 989.6 mm as shown in Figure 3. Each of Figures 8A-8C shows the fifth skeletal structure 45 along only a portion of its length, as described below. The portion in Figure 8C is located distally from the portion in Figure 8A. The portion in Figure 8B is located distally from the portion in Figure 8C. The fifth skeletal structure 45 of the scaffold 7 has multiple helical slots interconnected in an end-to-end manner along the longitudinal direction 10. Each helical slot has a few helical turns. For example, Figure 8A shows helical slots 61 and 62, Figure 8C shows helical slots 63 and 64, and Figure 8B shows helical slots 65 and 66. Each two interconnected ones of the helical slots have opposite winding directions relative to each other. Such a connection of two interconnected helical slots is shown longitudinally centrally in each of Figures 8A-8C. Figures 8A-8C further serve to illustrate that the pitch of the helical slots gradually decreases for subsequent helical slots distally along the longitudinal direction 10. Due to this decreasing pitch, the overall backbone cutout ratio of the fifth subsection 35 of the catheter wall 2 gradually increases distally, which has the effect of gradually increasing the flexibility of the fifth subsection 35 of the catheter wall 2 distally along the longitudinal direction.

[0039] 1-8 illustrate that the skeleton of a catheter according to the present invention may be formed at least in part by many different skeleton (sub)structures, such as the illustrated skeleton structures 41-45 of FIGS. 4-8, respectively.

[0040] The present invention can be practiced with many different configurations, many different materials, many different shapes, and many different sizes of the catheter skeleton, inner liner, and outer laminate, as well as many different additional features and many different attachments to the catheter, such as those used in known microcatheters for interventional cardiovascular and / or neurovascular applications, as long as the catheter falls within the scope of the appended claims.

[0041] It should be noted that a first location 100 mm proximal from the distal end, i.e., at the transition between the proximal and distal sections, does not necessarily imply a transition in architectural structure between the proximal and distal sections. Similarly, it should be noted that a second location 7 mm proximal from the distal end, i.e., at the transition between the distal tip and the remainder of the distal section, does not necessarily imply a transition in architectural structure between the distal tip and the remainder of the distal section. Indeed, as used herein, the definitions of proximal section, distal section, and distal tip only serve to quantify the overall skeletal cutout ratio of the distal section and distal tip, respectively, of a catheter in accordance with the present invention.

[0042] The following general note regarding the overall skeletal cutout ratio is made: if, in any longitudinally continuous longitudinal section of the catheter wall, the catheter wall has a completely uninterrupted tubular metal reinforcing wall, for example, in the form of a completely uninterrupted metal hypotube, then that longitudinal section will have an overall skeletal cutout ratio of 0%.

[0043] Furthermore, according to the present invention, it should be noted that typical dimensions of some portions and aspects of the present invention, as well as applicable practical ranges of such dimensions, are as follows: The effective length of the catheter (measured from the distal end of the catheter hub) may range from 130 cm to 160 cm, and may typically be 135 cm. The maximum outer diameter of the first distal section of the tubular catheter wall of the catheter may range from 0.60 mm to 1.20 mm, and may typically be 0.75 mm, but it should be noted that the term "maximum" in the term "maximum outer diameter" refers to the maximum value considered over the entire length of the first distal section. The minimum inner diameter of the first distal section of the tubular catheter wall of the catheter may range from 0.36 mm to 0.55 mm, and may typically be 0.45 mm, but it should be noted that the term "minimum" in the term "minimum inner diameter" refers to the minimum value considered over the entire length of the first distal section. For example, the following typical combinations of maximum outer diameter and minimum inner diameter of the first distal section are possible: A maximum outer diameter of 0.75 mm in combination with a minimum inner diameter of 0.45 mm, a maximum outer diameter of 1.20 mm in combination with a minimum inner diameter of 0.55 mm, or a maximum outer diameter of 0.60 mm in combination with a minimum inner diameter of 0.36 mm.

Claims

1. A catheter (1), which is a microcatheter for interventional cardiovascular and / or interventional neurovascular applications, comprising: The catheter comprises a tubular catheter wall (2) surrounding a luminal structure (3) of the catheter, the catheter wall having a proximal end (4), a distal end (5), and a longitudinal direction (10) extending from the proximal end to the distal end, the catheter wall having a length of at least 1000 mm along the longitudinal direction from the proximal end (4) to the distal end (5); The catheter wall (2) a proximal section (6) defined to extend distally from said proximal end (4) along said longitudinal direction to a first position (21) 100 mm proximal from said distal end (5); a distal section (14) defined to extend distally along said longitudinal direction from said first location (21) to said distal end (5); a distal tip (15) of the catheter (1), wherein the distal section (14) is defined to extend proximally along the longitudinal direction (10) from the distal end (5) to a second position (22) 7 mm proximal from the distal end (5); The catheter wall (2) has, at least in part of the distal section (14), a scaffold (7) for providing reinforcement of the catheter wall (2) not only in the longitudinal direction (10) but also in a circumferential direction (11) about the longitudinal direction (10), wherein the scaffold (7) is an interrupted tubular reinforcing wall obtained by micromachining a cut pattern (7A) into a completely uninterrupted tubular reinforcing wall made of a reinforcing material, the reinforcing material of the scaffold extending continuously anywhere along a continuous scaffold extent along the longitudinal direction to form at least one elongated continuous reinforcing structure along the entire continuous scaffold extent, the continuous scaffold extent extending distally along the longitudinal direction from at least a first position (21) to a position 2 mm proximal from the distal end (5); an inner liner (8) coaxially surrounded by the skeleton (7) relative to the centerline (12) of the catheter wall (2), at least in the continuous skeleton area; an outer laminate (9) coaxially surrounding the skeleton (7) relative to the centerline (12) of the catheter wall, at least in the continuous skeleton area; The total skeletal cutout ratio of the longitudinal section of the catheter wall (2) in the longitudinal extent along the longitudinal direction (10) is: - of the volume of all portions within said longitudinal extent of said reinforcing material that are cut out from said completely uninterrupted tubular reinforcing wall according to said micromachined cut pattern (7A), - the volume of all parts of the completely uninterrupted tubular reinforcing wall within the longitudinal extent of the reinforcing material, the total skeletal cutout ratio of all portions of the distal section (14) within the continuous skeletal range is at least 50%; A catheter (1) wherein the total skeletal cutout ratio of all portions of the distal tip (15) within the continuous skeletal range is at least 20%.

2. 2. The catheter (1) of claim 1, wherein the continuous skeletal area extends distally along the longitudinal direction (10) from at least the first location (21) to a location 0.5 mm proximal to the distal end (5).

3. 3. The catheter (1) of claim 2, wherein the continuous skeletal area extends distally along the longitudinal direction (10) from at least the first location (21) to a location 0.2 mm proximal from the distal end (5).

4. the total skeletal cutout percentage of all portions of the distal section (14) within the continuous skeletal range is at least 65%; 10. The catheter (1) according to any one of the preceding claims, wherein the total skeleton cut-out ratio of all the portions of the distal tip (15) that lie within the continuous skeleton range is at least 40%.

5. the total skeletal cutout percentage of all portions of the distal section (14) within the continuous skeletal range is at least 80%; 5. The catheter (1) of claim 4, wherein the total skeleton cutout percentage of all portions of the distal tip (15) within the continuous skeleton range is at least 60%.

6. 10. A catheter (1) according to any one of the preceding claims, wherein the radiopaque elements are embedded in the catheter wall (2) in that they are located in the spaces of the cut pattern (7A), the spaces being bounded by the framework (7), the inner layer (8) and the outer laminate (9).

7. 10. A catheter (1) according to any one of the preceding claims, wherein the skeleton (7) has, distally along the longitudinal direction (10), a distal skeleton end (16) in the form of a circular edge of the skeleton, the circular edge having a center point on the center line (12) of the catheter wall (2).

8. 10. A catheter (1) according to any one of the preceding claims, wherein the distal tip (15) is a tapered distal tip in that the distal tip (15) has an outer diameter that gradually narrows distally along the longitudinal direction (10) to the distal end (5).

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