Catheter steering device

Abstract

The system includes an outer member, an elongated post extending distally from the outer member, and an inner member coaxially positioned on and attached to the post, the inner member extending distally from the outer member and having a distal portion. The catheter is positioned within an outer catheter, e.g., an aspiration catheter, which provides a stiffening member that fits over the post and limits movement of the post, such that movement of either the inner or outer member relative to the other limits axial compression of the post by the inner wall of the outer member, causing a distal portion of the inner member to deflect laterally and redirect the outer member.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION This application relates to medical devices, and more particularly to medical devices that steer catheters to aid in navigating tortuous pathways.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 111,122, filed November 9, 2020. [Background technology]

[0003] The need to steer catheters through tortuous paths is widely recognized, and there are several approaches to achieving such steerability.

[0004] A coaxial catheter disclosed in U.S. Pat. No. 9,233,225 (hereinafter "the '225 patent") by the same inventor as the present application is a deflectable catheter having a deflection mechanism in the form of a post that deflects the catheter. The post is attached at one end to an inner catheter and at the other end to an outer catheter. A stiffening tube fits over the post to limit axial movement of the post, such that movement of either the inner or outer member relative to the other limits axial compression of the post by the inner wall of the outer member, causing a distal portion of the inner member to deflect laterally and redirect the outer member.

[0005] While the catheter of the '225 patent has a low profile and achieves deflection in a less cumbersome and consistent manner, in certain applications it may be beneficial to reduce this profile even further, and in certain applications it may be beneficial to design the post so that it can be used with a variety of catheters.

[0006] Current catheters also have difficulty navigating tortuous anatomies, such as neurovascular anatomy. Due to the varying sizes of certain catheters, such as aspiration catheters, and the small diameter of the guidewire or catheter over which they are inserted, these catheters often become stuck at vascular junctions, known as the ledge effect, and / or a shoulder between the catheter and the inner guidewire or inner catheter can cause damage to the vessel wall, potentially leading to dissection or subarachnoid hemorrhage. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 9,233,225 Summary of the Invention [Problem to be solved by the invention]

[0008] It would be advantageous to provide a system that improves catheter navigation through tortuous vasculature while avoiding the risk of snagging or causing vascular trauma at vascular junctions. Such a system for certain applications would advantageously have a reduced profile or facilitate the crossing of blood clots. [Means for solving the problem]

[0009] The present invention provides a bidirectional deflectable device that provides a low (reduced) profile and allows for use with a variety of catheters. Thus, the device of the present invention can be inserted into standard or specially designed catheters and is operable to cause deflection of such catheters that is achievable without the need to modify the catheter's structure.

[0010] The coaxial bi-directional deflectable instrument / system of the present invention facilitates navigation through tortuous vasculature and reduces the potential for the catheter to become caught at a vascular junction during insertion, while also reducing the risk of trauma during insertion / navigation, e.g., reducing the risk of vessel dissection or bleeding.

[0011] In one aspect, the present invention provides a deflectable device (e.g., a deflectable catheter) that is positioned within a separate outer catheter, and that deflects the outer catheter using a device deflection mechanism, i.e., a post.

[0012] In another aspect, the present invention provides a system including an outer member having a proximal portion and a distal portion, an inner member positioned coaxially within the outer member and extending distally of the outer member and having a distal portion, and an elongated post attached to the inner member and extending outside of the inner member, a first device slidably positioned within the lumen of the outer catheter such that the post is positioned within the lumen of the outer catheter, and when one of the inner or outer members is moved relative to the other, axial compression of the post is limited by the inner wall of the outer catheter, thereby laterally deflecting the distal portion of the inner member and redirecting the outer catheter.

[0013] In some embodiments, the inner member has a central longitudinal axis and the post members are radially offset from the central longitudinal axis.

[0014] In some embodiments, the outer catheter is a suction catheter.

[0015] In some embodiments, the post has a non-circular cross section.

[0016] Some embodiments further include a marker band disposed on the inner member, the post being attached to the marker band.

[0017] In some embodiments, the post has a proximal end attached to the outer member and a distal end attached to the inner member.

[0018] In some embodiments, the post has a distal end adjacent the soft distal section of the inner member, the inner member extending a distance of about 2 cm from the distal end of the post.

[0019] In some embodiments, the post is fitted with a stiffening material that contacts the inner wall of the second catheter during deflection.

[0020] In some embodiments, the post contacts the inner wall of the outer catheter during deflection.

[0021] According to another aspect of the present invention, a system is provided that includes: a) an outer member having a proximal portion and a distal portion; b) an inner member coaxially positioned within the outer member, the inner member extending distally of the outer member, the inner member having a distal portion and a distal-most edge; and c) an elongated post attached to and extending outside of the inner member. The post has a first end attached to the outer member and a second end attached to the inner member. The second end of the post is positioned proximal to the distal-most edge to leave an elongated extension of the inner member extending distally of the post. When the post is restrained by the outer structure and one of the inner member or the outer member is moved relative to the other, the distal portion of the inner member deflects laterally.

[0022] The post preferably terminates at a distal end adjacent the soft distal section of the inner member.

[0023] In some embodiments, lateral deflection occurs when the post is constrained by the inner wall of a separate outer catheter that houses the post.

[0024] In some embodiments, a marker band is provided on the inner member spaced proximally from the distal-most edge or elongated portion, and the post is attached to the marker band.

[0025] According to another aspect of the present invention, there is provided a method of redirecting a catheter into a vascular system, the method comprising: a) inserting a first device into an outer catheter, the first device having an inner member, an outer member, and a post member coupled to the inner member and / or the outer member; b) moving one of the inner member or the outer member relative to the other such that the inner member restricts movement of the post as it bends within the lumen of the outer catheter, resulting in a distal portion of the inner member deflecting laterally; c) advancing an outer catheter over and along the deflected distal section to redirect the catheter.

[0026] The outer catheter can be advanced independently over and along the device, or can be advanced with the device as a unit.

[0027] In some embodiments, the post is deflected into contact with the inner wall of the outer catheter and anchors the first device.

[0028] In some embodiments, the outer catheter is a suction catheter.

[0029] In some embodiments, manipulation of the distal portion of the first instrument via the post redirects the outer catheter away from the ophthalmic artery junction.

[0030] In some embodiments, the method further includes moving the post to stabilize the exposed section of the inner member.

[0031] In some embodiments, the method further includes advancing a portion of the inner member extending distally from the post through a clot in the blood vessel, hi some embodiments, the method further includes passing a stentriever or other clot treatment device through the inner member after the portion of the inner member has passed through the clot.

[0032] Preferred embodiments of the present disclosure are described herein with reference to the drawings. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 1 is a side view of a prior art flexible catheter disclosed in U.S. Pat. No. 9,233,225. [Figure 2] FIG. 2 is a side view of the prior art outer catheter of FIG. 1 showing a post extending from the outer catheter. [Figure 3] 2 is a side view of the prior art inner catheter of FIG. 1 within an outer catheter to form a flexible catheter (with the stiffening tube omitted for clarity of the drawing). FIG. [Figure 4] FIG. 4 is an enlarged view of the distal portion of the flexible catheter of FIG. 3, showing the lateral reinforcing (supporting) tubes removed to reveal the post members. [Figure 5] FIG. 5 is an enlarged view of the distal portion of the flexible catheter of FIG. 4 with lateral stiffening tubes. [Figure 6] FIG. 10 is a side view of a distal region of a deflectable device for deflecting an outer catheter, in accordance with one embodiment of the present invention. [Figure 7] FIG. 10 is a side view of the distal portion of an alternative embodiment of the deflectable device of the present invention with lateral support tubes. [Figure 8] 7 illustrates the deflected state of the device of FIG. 6 when the inner member is pulled proximally relative to the outer member. [Figure 9] 7A and 7B illustrate the deflected state of the catheter of FIG. 6 when the inner member is moved distally relative to the outer member. [Figure 10]FIG. 7 is a side view of the device of FIG. 6 inserted into a suction catheter. [Figure 11] FIG. 11 illustrates the deflected state of the device and suction catheter of FIG. 10, with the suction catheter acting as a support tube for the deflection. [Figure 12A] FIG. 10 is a perspective view showing how the aspiration catheter gets caught at the ophthalmic artery junction in the neurovasculature. [Figure 12B] FIG. 12B is a view similar to FIG. 12A showing an aspiration catheter guided by a small diameter distal access catheter. [Figure 12C] 7 illustrates the use of the device of FIG. 6 of the present invention to deflect an aspiration catheter within the neurovasculature. [Figure 12D] 7 illustrates the use of the device of FIG. 6 of the present invention to deflect an aspiration catheter within the neurovasculature. [Figure 13A] 7A and 7B illustrate the use of the device of FIG. 6 in a clot dislodging procedure, showing the crossing of the clot by a guidewire. [Figure 13B] 7 illustrates the use of the device of FIG. 6 in a clot dislodging procedure, showing the distal end of the device moved distally to cross the clot. [Figure 13C] 7 illustrates the use of the device of FIG. 6 in a clot dislodging procedure, with the device in place with the guidewire removed. [Figure 13D] 7A and 7B illustrate the use of the device of FIG. 6 in a clot dislodging procedure, showing the deployment of a stentriver through the inner member. [Figure 13E] 7A and 7B illustrate the use of the device of FIG. 6 in a clot dislodging procedure, showing suction through the outer catheter. [Figure 13F] 7A and 7B illustrate the use of the device of FIG. 6 in a clot dislodging procedure, showing proximal movement of the stentriver to remove the clot. DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention provides a highly deflectable, bidirectionally deflectable device (catheter) that allows and facilitates tip deflection within narrow, tortuous vasculature. The device has a deflectable distal section that deflects due to the arrangement of an inner member, an outer member, and a spine. The spine is attached to the inner and outer members. The device is insertable into an outer catheter, such as an aspiration catheter, midcatheter, or other catheter, such that the device's spine is positioned within the lumen of the outer catheter, with the inner wall of the outer catheter's lumen acting as a limiting member for the spine's movement. Relative movement of the outer and inner members causes lateral deflection of the device's distal section due to a limiting member (provided by the outer catheter) limiting axial movement of the spine, as described in more detail below.

[0035] In the devices of the present invention, the post is positioned proximally and sufficiently spaced from the distal tip of the inner member to provide a low profile that allows for, for example, crossing of a blood clot, as also described in more detail below.

[0036] U.S. Patent No. 9,233,225, assigned to the same inventor as the present application, discloses a deflectable catheter having a deflection mechanism in the form of a post that deflects the catheter. The post is attached at one end to an inner catheter (member) and at the other end to an outer catheter (member). A stiffening tube is fitted over the post to limit axial movement of the post, such that when either the inner or outer catheter is moved relative to the other, the stiffening tube limits axial compression of the post, thereby deflecting the distal tip of the inner catheter laterally.

[0037] While the catheter of the '225 patent advantageously has a low profile and achieves deflection in a less cumbersome and consistent manner, in certain applications it may be beneficial to further reduce this profile, for example, to cross a blood clot. Also, in certain applications it may be beneficial to design the post so that it can be used with a variety of catheters, i.e., so that the restricting member is not "built into" the device.

[0038] Figures 1-5, labeled "Prior Art," illustrate features of the catheter of the '225 patent to facilitate understanding of the present invention. Figures 1-5 will be described first, followed by a detailed description of the device of the present invention. The following description of Figures 1-5 provides an overview, and further details can be found in U.S. Pat. No. 9,233,225 (hereinafter "the '225 patent"), which is incorporated by reference and incorporated herein in its entirety.

[0039] In Figures 1-5, the motion-limiting (stiffening) member is part of (integrated into) the catheter to provide catheter deflection. In Figures 6-11, the motion-limiting (stiffening) member is provided by a separate outer catheter in which the device of the present invention is positioned, and the device of the present invention is used to deflect the outer catheter.

[0040] Referring to Figure 1, the prior art bidirectional coaxial deflectable microcatheter of the '225 patent is shown. The catheter 10 has an inner catheter (member) 12, an outer catheter (member) 24, and a distal section 48 with a deflectable tip.

[0041] The inner catheter 12 extends between a proximal end 16 and a distal end 58 having an inner lumen with a diameter ranging from approximately 0.001 inch to 1.993 inch, with a preferred inner diameter of approximately 0.017 inch (1 inch equals 25.4 mm). Coupled to the proximal end of the inner catheter body 14 is a winged hub 20 that is mounted to rest on a strain relief 22. The winged hub 20 may also include a rotating hemostatic valve (RHV) 18 to provide a channel into the inner lumen of the inner catheter 12 to allow for the insertion of accessories or the introduction of fluids through the side arms.

[0042] The inner catheter 12 has a catheter body 14 having a stiff proximal section constructed of a braided reinforced polymer tube extending between a proximal end 16 and a distal-most end 58. The proximal section is joined at its distal end to a less stiff distal tube. The inner catheter body 14 further has a laser-cut tube 76 (FIG. 4) joined to the distal end of the distal tube.

[0043] In one embodiment, the inner catheter has an anti-friction inner liner extending from the proximal end to the distal end to help reduce the coefficient of friction and thereby aid in guidewire movement within the inner catheter.

[0044] The '225 patent discloses various embodiments of the inner catheter in which the post extends to approximately the end of the inner catheter.

[0045] The outer catheter 24 extends between a proximal end 28 and a distal end 44 and has an inner lumen having a diameter ranging from about 0.007 inches to about 1.999 inches, with a preferred inner diameter of about 0.027 inches. The outer catheter body 26 has a relatively stiff proximal section 40 joined to a relatively soft distal section 42. Coupled to the proximal end of the outer catheter body 26 is a winged hub (luer) 34 that rests on a strain relief 38 (FIG. 2). Attached to the winged hub 20 is a rotating hemostatic valve (RHV) 32 with an end cap 30 and side arms 31. The end (locking) cap 30 serves as the locking assembly for the deflectable catheter, and the side arms 31 are used for the introduction of fluids for lubrication and, optionally, visualization. When the cap 30 is fully opened, the inner catheter 12 is free to move axially, resulting in deflection of the distal tip 48, as described below. The cap 30 can be closed at any time during the deflection process to clamp and hold the inner catheter 12 in place, thereby locking the tip 48 in place.

[0046] The deflectable tip 48 of the inner catheter 12 is covered by a lateral support tube 50, which overlaps a post, described below. The illustrated support tube 50 (shown in FIGS. 2 and 5) has its proximal end 46 and distal end 52 attached. The lateral support tube 50 is a helically wound flexible coil. Distal to the lateral support tube 50 is a radiopaque marker band 54, which has an end 56 attached to the distal-most end 58 of the inner catheter 10.

[0047] The outer catheter 24 may include a friction-reducing liner 128 that extends from the proximal end 28 to the distal end 44 and reduces the coefficient of friction between the inner diameter of the outer catheter and the outer diameter of the inner catheter, thereby aiding in the movement of the inner catheter during the deflection process. The catheter includes a laser-cut tube and a distal braid. A reinforcing layer is applied to the liner. The reinforcing layer is coated with a polymer with graded stiffness to create three distinct sections, with the stiffness decreasing from the proximal section 118 to the distal section 122. The outer catheter body 26 includes a marker band 138 that is inserted halfway into the inner diameter at the distal end of the outer catheter body 26.

[0048] For example, various embodiments of outer catheters having continuous open pitch coils are disclosed in the '225 patent.

[0049] The catheter 10 has a post, e.g., a wire or tube, extending distally from the outer catheter 24 (or 524) and attached to the inner catheter, the post being surrounded by a restraining (supporting) tube to limit lateral movement of the post. As shown, the post includes a post or column 140, the proximal end of which rests on or within a slot in the marker band 138. The proximal portion of the post 140 is inserted into the inner circumference, i.e., into the catheter body wall, at the distal end of the outer catheter body 26. The post 140 has a substantially rectangular cross-section.

[0050] The inner catheter 12 and outer catheter 24 are aligned and joined together by a marker band 54 and an adhesive or solder joint 56 at the distal portion.

[0051] The alignment of the distal end of the post 140 with the inner catheter 12 (the distal ends lie approximately in the same plane) is shown in FIG.

[0052] Figure 5 shows the distal section 150 with the lateral support tubes 50 in place, which form the cover for the post. The lateral support tubes 50 are fine-pitch, helically wound flexible coils made of platinum / iridium. Figure 4 shows the distal section 150 before attachment to the support tubes 50.

[0053] Figure 12A of the '225 patent shows the distal portion of the inner catheter under axial tension without the lateral support tubes 50. When the inner catheter body is pulled axially in the proximal direction by a load, the internal structure tends to shorten, thereby shortening the struts 140. Figure 12B of the '225 patent shows the effect when the inner catheter body is pulled axially in the distal direction by a load without the lateral support tubes 50. As shown, this applies a moment to the ends of the struts, causing them to bend.

[0054] Figures 13A and 13C of the '225 patent show the distal deflectable tip under an axial tensile load when lateral reinforcing (support) tubes 50 are provided. With the lateral support tubes 50 in place and an axial tensile load applied, the struts 140 can no longer compress axially due to the reinforcement of the struts by the tubes 50. As a result, the entire distal tip, including the main (guidewire) lumen, deflects.

[0055] Figures 13B and 13D of the '225 patent show the effect when the lateral support tubes 50 are provided and the inner catheter body is moved axially by a load 155 applied in a distal direction, which causes the distal tip to bend as shown, for example, in Figure 12B.

[0056] The '225 patent explains that proximal or distal movement of the inner catheter, respectively, is shown in Figures 12A-13D, and that the same effect can be achieved by distal or proximal movement of the outer catheter, or by movement of both the inner and outer catheters in the desired direction.

[0057] Catheter deflection via a post is described in the '225 patent as follows: "Bidirectional deflection of the distal tip of a coaxial microcatheter can be decomposed into two separate movements: axial pull deflection and axial push deflection. Axial pull deflection can be modeled as an eccentrically loaded post, and axial push deflection can be modeled as an eccentrically loaded beam."

[0058] With respect to axial pull deflection, if no lateral support tubes are provided at the distal end of the catheter, the strut is modeled as an unsupported, eccentrically loaded strut. This means that when the inner catheter is moved axially proximally with a force in the proximal direction, the distal end of the strut (rectangular nitinol wire) will attempt to move axially toward its proximal end, resulting in compression (buckling) of the strut. If lateral support tubes are provided, when the inner catheter is pulled axially with a force in the proximal direction, the strut will attempt to contract axially (buckle), but this will be limited by the lateral reinforcing tubes 50. Because the tip is no longer axially compliant (in compression), it will flex laterally (deflect).

[0059] For axial push deflection, if there are no lateral support tubes at the distal end of the catheter, the post is modeled as an eccentrically loaded beam, meaning that when the inner shaft is pushed axially with a force, it exerts a moment on the end of a beam (e.g., a rectangular nitinol wire), causing the beam to bend.

[0060] The axial push and pull described in the '225 patent can be thought of in terms of the x and y axes. The axial push and pull occurs on the x axis, and the bending (deflection) will end at a point (x, y). Thus, upon compression of the post causing the tip to bend to the y1 position, the distal end of the tip moves in the -x1 direction toward its proximal end (-x2).

[0061] Deflection of the distal tip is achieved by axial movement rather than pulling down on the distal tip, so that bending is achieved by axial movement rather than by tension in the direction of bending.

[0062] In the device disclosed in the '225 patent, a stiffening member (support tube) fits over a post that becomes part of the deflectable catheter when it is attached to the deflectable catheter. In the present invention of Figures 6 and 8-11, the device (catheter) is placed within an outer catheter, e.g., an aspiration catheter, and the deflection mechanism, i.e., post, is used to deflect the outer catheter, with the wall of the outer catheter acting as a stiffening / motion-constraining member (support tube) that deflects in the same manner as the support tube 50 does. Thus, the restricting member is not part of the device (catheter), and the device of the present invention can be used to deflect other, separate catheters into which it is inserted.

[0063] Figure 6 illustrates one embodiment of a bidirectional microcatheter (device) of the present invention with a deflectable tip. The distal section of a catheter 300 is shown in Figure 6 and includes an outer catheter 302 (also referred to herein as outer member 302) and an inner catheter 316 (also referred to herein as inner member 316) positioned within the lumen of the outer catheter 302 and extending distally therefrom. The inner catheter 316 has an exposed distal end 316a extending distally from the most distal edge of the outer catheter 302. The exposed distal end 316a may range, for example, from a minimum of 1 cm to over 5 cm, although other exposed lengths are also contemplated. This distal extension positions the post distal to the outer catheter while still positioning the post at a sufficient distance from the distal end of the inner catheter 316, as described below.

[0064] The outer catheter (member) 302 in this embodiment is a laser-cut stainless steel tube 303 having a non-laser-cut section 305 at its distal end 306 with laser-cut side holes 308. Other outer catheter structures, such as those described in the '225 patent, can be utilized. Reference numeral 304 in FIG. 6 indicates where the laser-cut section ends and the non-laser-cut section begins. The outer catheter 302 is formed of a tube 303 covered with a polymer 310, which preferably covers the entire length of the laser-cut tube to the end 304, leaving the non-laser-cut section 305 of the tube exposed (uncovered). An inner PTFE liner (not shown) extends the length of the tube 303 to the end 304. This leaves a portion of the tube 303 below the non-laser-cut section 305 and without the PTFE liner.

[0065] A marker band 312 is partially inserted into an opening in the distal end 306 of the tube 303, and may be welded, soldered, glued (or otherwise attached) in place using holes 308 if necessary. The marker band 312 may be inserted into the tube 303 up to the distal end 304, at which point the marker band abuts the PTFE liner, thus serving as a proximal stop for inner liner insertion. A post or post-like member 314 is provided resting on top of the marker band 312, and is inserted proximally into the tube 303 to a point near the distal end 304. The post 314 may be welded, soldered, glued, or otherwise attached at its proximal end to the tube 303 or to the non-laser cut section 305 using the hole 308. The post 314 may be circular or non-circular in cross section. The post 314 may be of various forms, such as a wire or a tube.

[0066] The inner catheter (member) 316 is placed within the outer catheter tube 303. During manufacture, the inner catheter is inserted into the distal opening of the marker band 312 with its exposed distal end region (section) 316a extending outward from the marker band 312. The inner catheter 316 has a lumen 323 that terminates at the distal end of the catheter 316. The exposed distal end region 316a has two portions: a proximal region 316b extending with the post 314 fitted therein and a distal region 316c free of the post 314. These regions are distributed depending on the ends of the post. For example, the post may be approximately 1.5 cm long. Other post lengths are also contemplated. The length of section 316c is determined by where the outer member with the attached post rests on the distal end region 316a, i.e., the length of the post 314. By way of example, if distal region 316a is 20 cm long and post 314 is 1.5 cm long, post 314 would be located 18.5 cm from the distal end, and thus region 316c would be 18.5 cm. Other lengths for sections 316a, 316b, 316c, and post 314 are contemplated. In the embodiment of FIG. 7, by way of example, the post distally terminates less than the midpoint of distal section 316a exposed from outer member 302. The length of distal region 316c, which has a reduced transverse dimension compared to post region 316b, is designed to allow passage through a clot, as described below, although other lengths are also contemplated. Inner catheter 316 may be constructed, for example, using methods described in the '225 patent or other methods. Additionally, the inner catheter is just one example of an inner catheter that can be used with other inner catheter configurations, such as those described in the '225 patent, but such configurations would need to be modified to accommodate the novel and advantageous columnar structure and positioning of the present invention.

[0067] The inner catheter 316 of Figure 6 is a variable stiffness design employing an inner PTFE liner, a proximal braid resting on the PTFE liner, and an outer coating made of polymers of different durometers that soften distally, resulting in a distal section that is softer than the proximal section. A platinum marker band 321 coated with a soft distal tip is located at the very distal end of the inner catheter 316. The inner catheter 316 may have a constant outer diameter or, alternatively, may taper along its length from proximal to distal to the marker band 318, where the diameter decreases and remains constant for a minimum length of preferably at least 1 mm and a maximum length preferably greater than 5 cm, although other lengths are also contemplated.

[0068] The exposed distal end 316a preferably has the same flexibility throughout; for example, the flexibility of section 316c is preferably equal to the flexibility of region 316b. Thus, the posts 314 may be positioned anywhere along the length of this soft region, i.e., terminate distally, depending on the desired length of the clot-crossing reduced-profile portion 316c. This section of the soft distal region 316a may range from about 15 cm to about 20 cm, although other lengths are also contemplated. The inner catheter has increased stiffness located proximal to the soft distal section. This increased stiffness may begin just proximal or further proximal to the distal section 316a. In a preferred embodiment, the posts are located only within the soft distal region 316a and not in the stiffer, more proximal regions of the inner catheter 316.

[0069] A marker band 318 is positioned on the inner catheter 316, and the marker band indicates the location of the distal end of the exposed distal section 316b. Beneath the marker band 318 are the distal ends of posts 314. The posts 314 may be welded, soldered, glued, or otherwise attached at their distal ends to the marker band 318 and / or the outer surface of the inner catheter 316. An adhesive joint 320 is provided at the distal end of the marker band 318 to attach the marker band 318 to the distal section 316a. The marker band 318 can be considered the boundary between the proximal region 316b (with posts) and the distal region 316c (without posts) of the exposed distal section 316a. Marker band 321, positioned at distal end 322 of catheter 316, is distal to marker band 318, which is in turn distal to marker band 312 attached to outer catheter 302. Note that while post 314 is shown below marker band 318, it may be located on top of marker band 318 and may be welded, glued, or soldered in place. Marker band 318 may further include a cover (not shown) that covers the entire marker band, with the outer diameter of such cover being equal to or greater than the outer diameter of outer catheter 302. Similarly, for this particular embodiment, the proximal end of post 314 may be attached to marker band 312 and / or outer catheter 302 using soldering, welding, glueing, or other forms of mechanical attachment. Thus, the post 314 is attached at its proximal end to the outer catheter 302 and at its distal end to the inner catheter 316 .

[0070] As shown, the inner catheter 316 extends distally from the post 314. That is, the post 314 has a distal end attached to the inner catheter 316, e.g., via the marker band 318 described above, and terminates proximal to the distal-most edge of the inner catheter 316. Thus, an elongated, longitudinally extending portion of the inner catheter 316 (referred to as the distal region 316c) extends distally from the post 314, such that the post 314 does not extend along the distal region 316c. In some embodiments, by way of example, the inner catheter 316 having a variable stiffness section may have a length of about 15 cm to about 20 cm. The marker band 318 is used to attach the post 314, and the marker band is spaced from the distal-most edge of the inner catheter 316. The length / spacing (including exposed distal section 316c) can be designed / varied to cross clots of different sizes. Thus, the system of outer catheter marker band 308, marker band 318, and post 314 can be positioned on inner catheters other than that shown in FIG. 6 to provide different lengths of section 316c (no post provided).

[0071] The inner catheter 316 has a distal region that is softer than the proximal region, and this soft region includes at least a distal region (segment) 316a. Thus, the region 316b adjacent to the posts 314 and the elongated region 316c without posts 314 are within the soft region of the inner catheter 316a. In other words, the proximal and distal ends of the posts 314 are located adjacent to the soft distal region of the inner catheter. The region proximal to this soft (more flexible) region is rigid and likely to not deflect. That is, the inner catheter has a soft distal section, which may be, for example, about 15 cm to about 20 cm, with the posts resting on any portion of it (but remaining distal to the next, more proximal, section of the catheter, which is stiffer). In some embodiments, distal region 316c may be softer than region 316b.

[0072] Figure 7 shows another alternative embodiment of the distal section 324 of a bidirectional microcatheter with a deflectable tip. This configuration is identical to the distal section 300 of the catheter of Figure 6, except for the lateral support tubes 326 that cover the post 334 and are located proximal to the distal region 316c of the exposed distal section 316a. The lateral support tubes 326 are constructed of a stainless steel coil 328 and coated with a dip-coated silicone 330, which has a proximal end 332 abutting the end 304 and a distal end 336 with an adhesive joint 337 located at the distal end of the support tube 326. A proximal adhesive joint (not shown) attaches the support tube 326 to the outer catheter. The support tube 326 can act as a reinforcing / restricting member for the post 314. This embodiment has an integrated motion restriction tube, and therefore does not have the advantages of using a separate catheter as a reinforcing / restricting member, however the spacing of the posts 314 proximally from the distal end of the inner catheter does have the advantages of clot crossing and deflection of the separate catheter as described in the instructions for use below.

[0073] Use of the deflectable microcatheter 300 of Figure 6 is illustrated in Figures 8 and 9. When the inner catheter 316 is pulled back relative to the outer catheter 302, or when the outer catheter 302 is pushed forward relative to the inner catheter 316 (or when the inner and outer catheters 316, 302 move in desired opposite directions), the post 314 tends to buckle or compress at region 314a, causing the exposed distal tip 316a to move in a downward motion (away from the bend in the post 314). When the inner catheter 316 is pushed relative to the outer catheter 302, or when the outer catheter 302 is pulled back relative to the inner catheter 316 (or upon movement of the inner and outer catheters 316, 302, in desired opposing directions), the post 314 attached to the inner catheter 316 begins to bend about region 338, and the exposed distal end 316a moves upward (toward the bend in the post 314). Note that region 316c bends, and at least a portion of region 316b may also bend.

[0074] Figure 10 shows the distal portion 300 of the bidirectional microcatheter of Figure 6 removably inserted inside a free-standing outer catheter in the form of an aspiration catheter 340. In this system, the aspiration catheter 340 acts as a lateral support tube.

[0075] The aspiration catheter 340 has an inner lumen 343 and a distal end 348 with a distal opening. The distal portion of the microcatheter 300 is positioned so that the post 324 is located within the lumen 343 of the aspiration catheter 340, and the exposed distal region 316c of the distal segment 316a extends distally of the distal end 348 of the aspiration catheter 340, such that at least a portion, preferably at least 50%, of the distal region 316b is exposed from the aspiration catheter 300. (In some embodiments, this means at least 1 cm, or alternatively, at least 2 cm, of the distal region, although other lengths are also contemplated.) By positioning the exposed distal region 316a in this manner, the aspiration catheter 340 can act as a lateral support tube that limits the movement of the post 314. That is, the aspiration catheter acts as a stiffening member during axial pull and axial push deflection in the manner described above for the built-in support tube 50. Thus, the post 314 of the present invention does not need to be part of the catheter 300 (as an integral part of the catheter) with a support tube that fits over the post 314, but rather a separate (independent) catheter can be used into which the post is inserted to limit its movement to achieve the deflection described herein. Note that this is accomplished because the post 314 is located within the confines of the distal portion of the aspiration catheter 340.

[0076] In some embodiments, the catheter does not have a longitudinally extending section of reduced profile, so that the post terminates distally adjacent the distal edge of the inner member, but the catheter does not have a stiffening tube; the catheter instead utilizes an aspiration catheter or other outer catheter into which the catheter is inserted to act as a stiffening member for deflection.

[0077] The inner lumen of aspiration catheters used to treat stroke tends to be a large diameter bore, and can vary from less than 0.030 inches to more than 0.088 inches. The aspiration catheter 340 is generally configured like a microcatheter with a PTFE liner 342, a reinforcing structure 344, and a polymer sheath 346. The reinforcing structure 344 can be a braid, a coil, a laser-cut tube, or a combination of these configurations. The polymer sheath 346 can be of various durometers that taper toward the distal end. Note that this is one type of configuration for an aspiration catheter; other forms of aspiration catheter configuration are also envisioned. Additionally, this is just one example of a post 314 that can be inserted into an off-the-shelf device or into a separate device to enable deflection of the separate device. This concept can be utilized with other catheters and devices that may be uncovered under suction in general terms, for example, an inner catheter with attached post 314 may be inserted into another catheter or tubular member to cause deflection in the manner described herein, as the catheter or tube acts as a stiffening member for post 314.

[0078] 11 shows the distal portion 300 of the bidirectional microcatheter deflected as shown in FIG. 8. However, the post 314 is now positioned within the aspiration catheter 340. When region 314a of the post 314 contacts the PTFE liner 342 of the outer aspiration catheter (or directly contacts the inner wall of the outer aspiration catheter in embodiments where an inner liner is not provided), the aspiration catheter 340 deflects as shown. This may also result in deflection of the exposed distal portion 316a of the inner catheter 316 as well as the guidewire 350 passing through the lumen of the inner catheter 316. Note that due to the large variations in inner diameter and stiffness possible in aspiration catheter designs, the overall dimensions of the bidirectional catheter, including the post 314, may vary as the bore size of the aspiration catheter increases.

[0079] The advantages of the deflectable catheter 300 with a post 314 when used in conjunction with an aspiration catheter (or other stand-alone catheter) can be understood with reference to FIGS. 12A and 12B. The purpose of the aspiration catheter 340 is to perform revascularization in patients suffering from an ischemic stroke. One of the challenges in treating stroke is the tortuous anatomy of the neurovascular system. FIG. 12A shows a portion of the neuroanatomy 400 consisting of the internal carotid artery (cavernous) 402, the ophthalmic artery 404, and the posterior communicating artery 406. Navigating this portion of the anatomy creates a problem known as the shelf effect, with large lumen catheters tending to get stuck at the ophthalmic artery junction 408. As shown in FIG. 12A, the aspiration catheter 340 fails to track the guidewire 350 due to its large lumen relative to the small wire.

[0080] To address this, various companies have introduced distal access or distal assist catheters, which are small-diameter catheters placed within large-bore aspiration catheters. In this setup, a coaxial system allows the aspiration catheter 340 to be guided over a guidewire 350 by a small-diameter distal access catheter 352, as shown in FIG. 12B. However, there is still a shoulder 354 between the catheters that can damage the vessel wall and potentially cause dissection or subarachnoid hemorrhage.

[0081] In addition to distal access or assist catheters, companies have introduced large diameter guidewires and tapered microcatheters as potential solutions. A problem with these designs is that they lack the ability to truly redirect the entire aspiration catheter tip. This problem is solved by inserting any of the above-described embodiments of a bidirectional microcatheter into the lumen of the aspiration catheter. The bidirectional catheter of the present invention allows the user to manipulate the guidewire and redirect the aspiration catheter tip.

[0082] In addition to using aspiration catheters to treat stroke, interventional neuroradiologists sometimes use other clot retrieval tools, such as stentrievers. These devices are sometimes used in combination with aspiration catheters, but they require small inner / outer diameter catheters for delivery and crossing the clot for deployment. Because clot crossing should be performed with the smallest possible diameter catheter, companies have introduced tapered distal assist catheters, such as those described above. While these designs offer a small distal profile for crossing, they still suffer from the small shoulder issues associated with coaxial systems, such as those described above. The use of the bidirectional catheter of the present invention with an exposed distal tip allows for a low crossing profile and complete aspiration tip and guidewire control.

[0083] 12C and 12D show a bidirectional microcatheter whose distal section is positioned within an aspiration catheter 340 and configured to be advanced over a guidewire 350. As shown in FIG. 12C, a shoulder 354 exists between the microcatheter distal section 300 and the aspiration catheter 340 due to the size mismatch. If left unassisted, this system may contact the ophthalmic artery junction 408 in a manner similar to that shown in FIG. 12A. However, as shown in FIG. 12D, manipulating the distal end of the bidirectional catheter with the post 314 of the present invention results in the distal end 348 of the aspiration catheter 340 being redirected away from the junction 408 toward the center of the artery. It is noted that the distal section can also have a larger diameter that transitions to a smaller diameter 316a to traverse the clot, minimizing the shoulder 354.

[0084] Once the coaxial aspiration system reaches the clot, the first step is to traverse the clot and position a stentriver for clot removal. Figures 13A-13F show the overall steps for treatment. Figure 13A shows first using a guidewire 350 to traverse a clot 412 in a blood vessel 409 having an inner vessel wall 410. For this step, the post 314 may be used to stabilize the distal exposed section 316a by moving the inner catheter 316 (not shown) until region 314a of the post 314 contacts the wall 410. Once the guidewire 350 has traversed the clot 412, the post 412 is flattened and the exposed distal region 316 of the exposed distal end 316a is pushed forward through the clot 412, as shown in Figure 13B. Next, guidewire 350 is removed as in Figure 13C, and stentriever 358 with delivery wire 356 is deployed as shown in Figure 13D. The bidirectional microcatheter is then removed, and aspiration (see arrow 360) is applied through the inner lumen 343 of aspiration catheter 340, as shown in Figure 13E. Next, under aspiration, stentriever 358 is drawn into the clot using delivery wire 356 (see arrow 380), and the entire coaxial system is drawn together as shown in Figure 13F, dislodging and removing the clot from the body. It should be noted that the steps in Figures 13A-13F for clot removal are merely exemplary, as fewer or more steps may be utilized with the deflectable inner catheter / post of the present invention to enhance access. As can be seen, the low profile distal section 316c of the exposed distal region 316a of the inner catheter 316, free of the posts 314, facilitates crossing of the clot.

[0085] In summary, according to one method of the present invention, there is provided a method of directing a catheter into a vascular system, the method comprising the steps of inserting a first device into an outer catheter, the first device having an inner member, an outer member, and a post connected to the inner member and / or the outer member, the method comprising moving one of the inner member or the outer member relative to the other to allow axial compression of the post as it is bent within the lumen of the outer catheter, the inner wall restricting movement of the post so that a distal portion of the inner member is deflected laterally, and the method comprising advancing the outer catheter over and along the deflected distal portion, either separately or together with the device, to redirect the outer catheter.

[0086] It should be noted that the catheter of the present invention can be used to deflect a variety of other instruments or tubular members, and such catheters are not limited to aspiration catheters.

[0087] While the above description contains many specifics, these specifics should not be construed as limitations on the scope of the disclosure, but merely as exemplifications of preferred embodiments of the invention. Those skilled in the art will envision many other possible variations that fall within the scope and spirit of the invention as set forth in the claims appended hereto.

[0088] Additionally, those skilled in the art will appreciate that elements and features illustrated or described in connection with one embodiment can be combined with elements and features of another embodiment without departing from the scope of the invention, and that the skilled artisan will appreciate additional features and advantages of the presently disclosed subject matter based on the description provided.

[0089] Throughout the above description, terms such as "approximately," "about," "generally," and "substantially" should be understood to allow for variations in any numerical range or technical concept to which they relate. For example, the use of terms such as "approximately," "about," "substantially," and "generally" should be understood to include variations on the order of 25% or to allow for manufacturing tolerances and / or variations in design.

[0090] The recitation of numerical ranges by endpoints includes all numbers within that range.

[0091] For example, although terms such as "first," "second," "third," etc. are used herein to describe various acts, elements, components, regions, and / or sections, these acts, elements, components, regions, and / or sections should not be limited by the use of these terms in that these terms are used to distinguish one act, element, component, region, or section from another act, element, component, region, or section. Thus, unless expressly specified otherwise, a first act, element, component, region, or section may be referred to as a second act, element, component, region, or section without departing from the scope of the invention.

[0092] Each and every claim is incorporated into the specification as a separate disclosure to become an embodiment of the present disclosure. Also, the phrases "at least one of A, B, and C" and "A and / or B and / or C" should be interpreted as including A only, B only, C only, or a combination of A, B, and C, respectively.

Claims

1. 1. A system comprising: a first instrument, the first instrument comprising: i) an outer member having a proximal portion and a distal portion; ii) an inner member coaxially positioned within the outer member, the inner member extending distally of the outer member, the inner member having a distal portion; iii) an elongated post attached to and extending outside of the inner member; a separate outer catheter having a lumen, wherein the first device is removably insertable into the separate outer catheter and slidably positioned within the lumen of the outer catheter so that the post is positioned within the lumen of the outer catheter, the post having a distal end terminating proximal to the distal-most edge of the inner member; When one of the inner or outer members is moved relative to the other, axial compression of the post is limited by the inner wall of the outer catheter, thereby causing the distal portion of the inner member to deflect laterally and redirect the outer catheter.

2. The system of claim 1 , wherein the inner member has a central longitudinal axis, and the post members are radially offset from the central longitudinal axis.

3. The system of claim 1 or 2, wherein the outer catheter is a suction catheter.

4. The system of claim 1 , wherein the post has a non-circular cross section.

5. The system of claim 1 , further comprising a marker band on the inner member, the post being attached to the marker band.

6. The system of claim 1 , wherein the post has a proximal end attached to the outer member and a distal end attached to the inner member.

7. 7. The system of claim 1, wherein the inner member extends a distance of about 2 cm from the distal end of the post.

8. A system described in any one of claims 1 to 7, wherein the distal end of the cylindrical member is located adjacent to a soft distal section of the inner member.

9. 9. The system of claim 1, wherein the post is fitted with a stiffening member, the stiffening member contacting the inner wall of the outer catheter during deflection.

10. The system of claim 1 , wherein the post contacts the inner wall of the outer catheter during deflection.

11. The system of claim 1 , wherein the inner member has a distal section that is softer than a proximal section.

12. The system of claim 11 , wherein lateral deflection occurs when the strut is restrained by an inner wall of the outer catheter in which the strut is positioned.

13. 13. The system of claim 11 or 12, wherein the post is attached at a first end to the outer member and at a second end to the inner member.

14. 14. The system of claim 13, wherein the second end of the post is positioned proximal to the distal-most edge of the inner member to leave an elongated portion of the inner member extending distally of the post.

15. The system of claim 13 or 14, wherein the second end terminates adjacent the softer distal section of the inner member.

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