Catheters and suction devices

Abstract

To increase a suction force at the time of suction using a catheter, and secure flexibility of the catheter.SOLUTION: A catheter includes: a first hollow shaft; a cylindrical self extension member that can extend itself in a radial direction at a tip end side of the first hollow shaft; a second hollow shaft having an outer diameter smaller than an inner diameter of the first hollow shaft and storing a tip end portion of the self extension member; and a linear member having a tip end portion bonded to the second hollow shaft and installed to extend in the inside of the second hollow shaft, the self extension member, and the first hollow shaft. The self extension member has a shape in which the outer diameter of the entire self extension member becomes smaller than an outer diameter of the first hollow shaft when the tip end portion of the self extension member is stored in the second hollow shaft. When a force toward the tip end side is applied to the linear member, the second hollow shaft is detached from the tip end portion of the self extension member and the outer diameter of the self extension member extends itself in the radial direction until the outer diameter of the self extension member becomes larger than the outer diameter of the first hollow shaft.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a catheter and a suction device.

Background Art

[0002] As a device used for endovascular treatment such as the treatment of cerebral infarction, for example, a device provided with a suction catheter for thrombus retrieval is known (see, for example, Patent Document 1). Such a device has a funnel (stent) at the tip (distal end) of the suction catheter that can expand up to the diameter of the blood vessel. By expanding the funnel, the blood vessel is blocked to cut off blood flow, and then the thrombus is aspirated using the suction catheter. Further, the device is provided with a delivery catheter for guiding the funnel near the lesion. The funnel is housed in the delivery catheter together with the suction catheter until it is guided near the lesion and expands, and its expansion is suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Such devices house a funnel at the tip of the suction catheter within a delivery catheter along with the suction catheter itself. Therefore, the outer diameter of the suction catheter must be smaller than the inner diameter of the delivery catheter. While the suction force of the suction catheter can be increased by increasing its diameter, in the devices described above, the diameter of the suction catheter is limited by the delivery catheter. For this reason, it was desired to further increase the suction force of the suction catheter to improve the efficiency of thrombus retrieval. Furthermore, in the devices described above, there was a problem in that the flexibility of the delivery catheter, which houses the funnel, decreased when force was applied in the direction that expands the funnel. When the flexibility of the delivery catheter decreases, it can be difficult to guide the tip of the delivery catheter to the desired location (lesion site) in the curved cerebral blood vessels. Therefore, a technology to ensure the flexibility of the delivery catheter was desired. It should be noted that these challenges are common to all devices that remove foreign bodies from the luminal regions of living bodies, including the vascular system, lymphatic system, biliary system, urinary tract system, airway system, digestive system, secretory glands, and reproductive organs. [Means for solving the problem]

[0005] This disclosure can be implemented in the following forms: (1) According to one embodiment of the present disclosure, a catheter is provided. The catheter comprises a first hollow shaft, a tubular self-expanding member whose rear end is joined to the tip side of the first hollow shaft and whose tip is radially self-expanding, the self-expanding member comprising a tubular mesh member that is radially expandable and contractible, and a resin layer covering the mesh member, a second hollow shaft having an outer diameter smaller than the inner diameter of the first hollow shaft and housing the tip of the self-expanding member in a radially contracted state, and a tip joined to the second hollow shaft, with the portion on the rear end side of the portion joined to the second hollow shaft being connected to the second hollow shaft, the self-expanding member, and The self-expanding member comprises a linear member extending inside the first hollow shaft, wherein the self-expanding member has a shape such that when the tip of the self-expanding member is housed in the second hollow shaft, the overall outer diameter of the self-expanding member is smaller than the outer diameter of the first hollow shaft, and when a force is applied to the linear member from the rear end to the tip of the first hollow shaft, the second hollow shaft moves together with the linear member, the second hollow shaft detaches from the tip of the self-expanding member, and the self-expanding member expands radially until its outer diameter becomes larger than the outer diameter of the first hollow shaft. In this catheter design, the tip of a self-expanding member, which is joined to the tip of the first hollow shaft and expands on its own, is housed within a second hollow shaft having an outer diameter smaller than the inner diameter of the first hollow shaft. Therefore, when delivering the catheter within the body, there is no need to use a separate shaft to house the first hollow shaft along with the self-expanding member in order to accommodate the reduced-diameter self-expanding member. Thus, since the first hollow shaft does not need to be housed within a shaft with a larger diameter, the diameter of the first hollow shaft is not limited by the diameter of the other shaft that houses it. Consequently, a larger diameter can be secured for the first hollow shaft, improving its suction capacity when used as a suction catheter. Furthermore, since the first hollow shaft does not need to house the self-expanding member, the flexibility of the first hollow shaft is not reduced due to the housing of the self-expanding member, thereby increasing safety when delivering the catheter within a biological lumen. Furthermore, by covering the mesh member with a resin layer, the degree to which the self-expanding member blocks the flow within the biological lumen is increased, thereby enhancing the effect of preventing foreign matter detached from the inner wall of the biological lumen by suction from being ejected distally. In addition, when suctioning and collecting foreign matter from within the biological lumen via the first hollow shaft, leakage of suction force in the self-expanding member can be suppressed. (2) In the catheter of the above form, the self-expanding member may have a bent portion such that, when viewed from a direction perpendicular to the central axis of the self-expanding member with the second hollow shaft removed from the tip of the self-expanding member, the angle of inclination in which the self-expanding member expands toward the tip is changed to approach the axial direction. With such a configuration, the angle between the wall of the biological lumen into which the catheter is inserted and the self-expanding member becomes smaller toward the tip than the bent portion of the self-expanding member, thereby reducing the possibility of the tip of the self-expanding member damaging the wall of the biological lumen. In addition, the operation of reducing the diameter of the self-expanding member and storing it inside the second hollow shaft becomes easier. This disclosure can be implemented in various forms other than those described above, for example, in the form of a suction device equipped with a catheter, or a method for manufacturing a catheter. [Brief explanation of the drawing]

[0006] [Figure 1] A partial cross-sectional view showing the schematic configuration of the catheter according to the first embodiment. [Figure 2] Schematic cross-sectional view of section AA in Figure 1. [Figure 3] A schematic diagram illustrating how the stent deforms in response to manipulation of the operating wire. [Figure 4] An explanatory diagram showing an example of the procedure for thrombus retrieval using a catheter. [Figure 5] An explanatory diagram showing an example of the procedure for thrombus retrieval using a catheter. [Figure 6] An explanatory diagram showing how the stent of the second embodiment expands within a blood vessel. [Figure 7] A partial cross-sectional view showing the schematic configuration of the catheter according to the third embodiment. [Modes for carrying out the invention]

[0007] A. First Embodiment: (A-1) Overall structure of the catheter: Figure 1 is a partial cross-sectional view showing the schematic configuration of the catheter 10 of the first embodiment. The catheter 10 is used, for example, in the treatment of cerebral infarction to physically remove thrombi from blood vessels. The catheter 10 has a first hollow shaft 20, a second hollow shaft 30, a stent 40, an operating wire 80, a connector 50, and a sealing portion 60. Note that Figure 1 and Figures 2-7 described later do not accurately represent the proportions of the dimensions of each part.

[0008] In Figure 1, the central axis passing through the center of the catheter 10 is represented by axis O (dotted line). In the example in Figure 1, axis O coincides with the central axes of the first hollow shaft 20, the second hollow shaft 30, and the stent 40. However, axis O may differ from the central axes of each of the components described above. The direction parallel to axis O is also called the "axial direction." Figure 1 also shows mutually orthogonal XYZ axes. The X-axis corresponds to the axial direction at the tip of the catheter 10 shown in Figure 1, the Y-axis corresponds to the height direction of the catheter 10, and the Z-axis corresponds to the width direction of the catheter 10. The left side of Figure 1 (-X-axis direction) is called the "tip side" of the catheter 10 and each component, and the right side of Figure 1 (+X-axis direction) is called the "proximal end side" of the catheter 10 and each component. In addition, in the catheter 10 and each component, the end located on the tip side is called the "tip," and the tip and its vicinity are called the "tip portion." Furthermore, the end located on the proximal side is called the "proximal end," and the proximal end and its vicinity are called the "proximal end." The distal end corresponds to the "distal end" which is inserted into the body, and the proximal end corresponds to the "proximal end" which is manipulated by a surgeon such as a physician.

[0009] The first hollow shaft 20 is a long, elongated member extending along the axis O. The first hollow shaft 20 is a roughly cylindrical shape with open ends (tip and base). The first hollow shaft 20 has a lumen 20L inside. The lumen 20L functions as a guidewire lumen for inserting a guidewire into the catheter 10, and also as a thrombus retrieval lumen for guiding thrombi aspirated through the tip 20d to a suction device. The outer diameter and length of the first hollow shaft 20 and the inner diameter of the lumen 20L can be arbitrarily determined. In this embodiment, the base end 40p of the stent 40 is joined to the tip 20d of the first hollow shaft 20. A connector 50 is also connected to the outer circumferential surface of the base end 20p of the first hollow shaft 20. The first hollow shaft 20 can also be constructed by joining multiple shafts together. In this case, the multiple shafts can be formed from the same material or from different materials.

[0010] The first hollow shaft 20 preferably has antithrombotic properties, flexibility, and biocompatibility, and can be formed from resin or metal materials. Examples of resin materials include polyamide resin, polyolefin resin, polyester resin, polyurethane resin, silicone resin, and fluororesin. Examples of metal materials include stainless steel such as SUS304, nickel-titanium alloy, and cobalt-chromium alloy. Furthermore, using radiopaque materials such as gold, platinum, tungsten, or alloys containing these elements is preferable as it improves the visibility of the first hollow shaft 20 under X-ray fluoroscopy. Alternatively, the first hollow shaft 20 may be formed by combining resin and metal materials, for example, by covering a tube formed from a metal mesh with a resin layer.

[0011] The stent 40 is a hollow cylindrical member that is expandable and contractible in the radial direction and has open ends (tip and base), and is equipped with a mesh member formed by weaving strands of wire. Figure 1 shows the stent 40 in a contracted state. As described above, the stent 40 is equipped with a mesh member, but in Figure 1 and Figures 3 to 5 described later, the stent 40 is shown only by lines representing its outer circumference in order to simplify its appearance and make the shape change easier to understand. The base end 40p of the stent 40 is joined to the tip 20d of the first hollow shaft 20, as previously described. The joining can be achieved by any method, for example, by joining with an adhesive such as epoxy adhesive, or by joining with metal solder such as silver solder, gold solder, zinc, Sn-Ag alloy, or Au-Sn alloy.

[0012] The stent 40 is radially expandable and contractible. When the catheter 10 is inserted into the body, the tip of the stent 40 is folded and stored within the second hollow shaft 30 in a radially contracted state, as shown in Figure 1. The stent 40 is also a self-expanding device. When the second hollow shaft 30 detaches from the tip, the tip self-expands radially around the proximal end. The stent 40 comprises a fixed diameter portion 45 at the proximal end, an outer peripheral portion 47 at the tip, and an intermediate portion 46 located between the fixed diameter portion 45 and the outer peripheral portion 47. The state of the stent 40 after expansion will be described later. The stent 40 is also called a "self-expanding member."

[0013] Figure 2 is a schematic cross-sectional view of the AA section shown in Figure 1. The stent 40 comprises a mesh member formed by weaving a plurality of strands 42 into a tubular shape. Each strand 42 may be a single strand or a double strand. In the case of a double strand, the configuration of the double strand can be arbitrarily determined, for example, it can be a stranded wire formed by twisting together a core wire (strand) placed in the center and strands arranged to surround the core wire. When a double strand is used, the wire diameter and material of the strands forming the double strand may be the same or different. For example, some of the strands 42 constituting the stent 40 may be single strands, and the remaining strands 42 may be double strands.

[0014] Each wire 42 is formed from a metal or resin material. Examples of metal materials include stainless steel such as SUS304, nickel-titanium alloy, and cobalt-chromium alloy. Alternatively, using radiopaque materials such as gold, platinum, tungsten, or alloys containing these elements is preferable as it improves the visibility of the stent 40 under X-ray fluoroscopy. Examples of resin materials include polyamide, polyester, polyacrylate, and polyetheretherketone. The same material may be used for all wires 42 constituting the stent 40, or different materials may be used for some of the wires 42. If different materials are used, combinations of different metal materials, different resin materials, or a combination of metal and resin materials can be employed.

[0015] Furthermore, the stent 40 includes a resin layer 44 made of resin that covers the mesh members constituting the stent 40. In the stent 40 of the present embodiment, the resin layer 44 is formed so as to cover the entire mesh member. By providing the resin layer 44, the gaps between the wire elements 42 in the mesh member are blocked. However, in the mesh member, the gaps between the wire elements 42 do not have to be completely blocked. As the resin constituting the resin layer 44, for example, polyurethane, polytetrafluoroethylene (PTFE), silicone resin, or the like can be used. The resin layer 44 can be formed by, for example, dipping the mesh member in a molten resin bath and then drying it with hot air.

[0016] Returning to FIG. 1, the second hollow shaft 30 is disposed at the tip of the catheter 10 and is a member that advances in the blood vessel ahead of other members. The second hollow shaft 30 extends along the axis O and has a hollow substantially cylindrical shape with both ends (the tip and the base end) open. The outer diameter of the second hollow shaft 30 is formed smaller than the inner diameter of the first hollow shaft 20. Since the second hollow shaft 30 advances in the blood vessel ahead of other members and abuts against the blood vessel inner wall prior to other members, it is preferably formed of a relatively soft material, for example, a resin material such as polyurethane or polyurethane elastomer. If the second hollow shaft 30 is made of resin, it becomes easier to ensure flexibility in the second hollow shaft 30 that houses the tip portion of the stent 40. If sufficient flexibility is obtained in the second hollow shaft 30, the second hollow shaft 30 may be configured to include a reinforcing member such as a metal mesh inside the resin layer. Also, at the tip of the second hollow shaft 30, a member (for example, a urethane tip) formed of a softer material than other parts of the second hollow shaft 30 may be provided.

[0017] The operating wire 80 is joined to the second hollow shaft 30 at a joint portion 31 provided at the tip of the second hollow shaft 30, and the portion on the proximal side of the joint portion 31 extends inside the second hollow shaft 30, the stent 40, and the first hollow shaft 20. The joint portion 31 is provided on the second hollow shaft 30 on the tip side of the position of the tip of the stent 40 when the tip of the stent 40 is housed in the second hollow shaft 30. In the catheter 10 of the present embodiment, when the operating wire 80 is moved relatively to the tip side with respect to the stent 40 and the first hollow shaft 20, the second hollow shaft 30 also moves relatively to the tip side with respect to the stent 40, and the second hollow shaft 30 comes off from the tip of the stent 40 in the state of FIG. 1. The operating wire 80 is also referred to as a "linear member".

[0018] The operating wire 80 only needs to have a rigidity such that the second hollow shaft 30 can be moved in the axial direction by moving the operating wire 80 in the axial direction in a state where the operating wire 80 is joined to the second hollow shaft 30 at the joint portion 31. The operating wire 80 can be formed of a metal material such as stainless steel such as SUS304, a nickel-titanium alloy, a cobalt-chromium alloy, a tungsten alloy, or the like. Further, the linear member configured as the operating wire 80 in the present embodiment may be other than wire-shaped, for example, at least a part thereof may be configured by a tubular member or a rod-shaped member.

[0019] The joining of the operating wire 80 and the second hollow shaft 30 at the joint portion 31 can be realized by any method, for example, it can be joining with an adhesive such as an epoxy-based adhesive. Alternatively, when at least the portion where the joint portion 31 is formed in the second hollow shaft 30 is formed of metal, joining by welding, brazing, or soldering may be used.

[0020] Figure 3 is a schematic diagram illustrating how the stent 40 deforms as the operating wire 80 and the second hollow shaft 30 move in conjunction with the operation of the operating wire 80 during the use of the catheter 10. As previously described, the stent 40 comprises a fixed diameter portion 45 at the proximal end, an outer peripheral portion 47 at the tip end, and an intermediate portion 46 located between the fixed diameter portion 45 and the outer peripheral portion 47. Figure 3(A), similar to Figure 1, shows the tip of the stent 40 housed within the second hollow shaft 30. In Figure 3(A), the application of a force toward the tip to the operating wire 80 in this state is indicated by a white arrow. In such a stent 40, the fixed diameter portion 45 at the proximal end of the stent 40 maintains almost the same diameter even when the stent 40 expands or contracts, and has a diameter similar to that of the first hollow shaft 20. Furthermore, the second hollow shaft 30, which houses the outer peripheral portion 47, which is the tip of the stent 40, has an outer diameter smaller than the inner diameter of the first hollow shaft 20. Therefore, when the outer peripheral portion 47 is housed inside the second hollow shaft 30, as shown in Figure 3(A), the outer peripheral portion 47 has the smallest diameter within the stent 40. In the stent 40 with the outer peripheral portion 47 housed inside the second hollow shaft 30, the intermediate portion 46 has a shape that gradually decreases in diameter from the constant diameter portion 45 towards the outer peripheral portion 47. Therefore, as shown in Figure 3(A), when the tip of the stent 40 is housed inside the second hollow shaft 30, the overall outer diameter of the stent 40 becomes smaller than the outer diameter of the first hollow shaft 20. In other words, when the tip of the catheter 10, including the tip of the first hollow shaft 20, is viewed from the axial direction, the outer circumference of the stent 40 is located inside the outer circumference of the first hollow shaft 20.

[0021] Figure 3(B) shows how the second hollow shaft 30 detaches from the tip of the stent 40 and self-expands as a result of the force described above being applied to the operating wire 80 toward the tip. As shown in Figure 3(B), when the second hollow shaft 30 detaches from the tip of the stent 40, the outer diameter of the outer circumference 47, which is the tip of the stent 40, becomes larger than the outer diameter of the first hollow shaft 20. In Figure 3(B), the application of a force toward the proximal end to the operating wire 80 in this state is indicated by a white arrow. Figure 3(C) shows how the operating wire 80 and the second hollow shaft 30 are pulled out through the inside of the stent 40 and the first hollow shaft 20 as a result of the force described above being applied to the operating wire 80 toward the proximal end.

[0022] When the second hollow shaft 30 detaches from the tip of the stent 40 and the stent 40 expands, the outer circumference 47 becomes the largest in diameter within the stent 40. The outer circumference 47 may have a nearly constant diameter when the stent 40 expands, or it may have a shape that gradually expands in diameter towards the tip. As will be described later, the outer circumference 47 is the part that contacts the inner wall of the blood vessel when the stent 40 expands within the blood vessel. When the stent 40 expands, the middle section 46 has a shape that gradually expands in diameter from the constant diameter section 45 towards the outer circumference 47. Therefore, the boundary between the middle section 46 and the outer circumference 47 is a bent section 48, as shown in Figure 3(C), where, when the stent 40 is viewed from a direction perpendicular to the central axis (perpendicular to the axial direction), the angle of inclination in which the diameter expands towards the tip is changed to approach the axial direction.

[0023] Returning to Figure 1, the connector 50 is positioned on the proximal end of the catheter 10 and is a component grasped by the operator. The connector 50 comprises a hollow bifurcated branch 59 and wing portions 51 and 52. Of the lumens of the branch 59, the lumen 51L connected to the first proximal end 59s functions as a guidewire lumen for inserting a guidewire into the catheter 10. Also, of the lumens of the branch 59, the lumen 52L connected to the second proximal end 59b functions as a thrombus lumen for guiding thrombi transported via the first hollow shaft 20 to an aspiration device. The shape, outer diameter, and length of the branch 59, and the inner diameters of the lumens 51L and 52L can be arbitrarily set. In this embodiment, the proximal end 20p of the first hollow shaft 20 is connected to the inner circumferential surface of the tip 59d of the branch 59. Furthermore, a wing portion 51 is joined to the outer circumferential surface of the first base end portion 59s, and a wing portion 52 is joined to the outer circumferential surface of the second base end portion 59b.

[0024] The wing portion 51 has a hollow shape with both ends (tip and base) open, and the operating wire 80 described above is exposed from the base end opening 51o which leads to the lumen 51L. The wing portion 52 has a hollow shape with both ends (tip and base) open, similar to the wing portion 51, and the base end opening 52o which leads to the lumen 52L is configured to allow attachment of a suction device (not shown). Any shape can be adopted for the wing portions 51 and 52. The wing portions 51 and 52 may also be omitted. The branch portion 59, the wing portion 51, and the wing portion 52 can be made of resin materials such as polyamide, polypropylene, polycarbonate, polyacetal, and polyethersulfone. There are no particular restrictions on the method of driving the operating wire 80. For example, the operating wire 80 may be driven in the forward and backward direction by rotating a member attached to the catheter 10 and converting the rotational motion into linear motion, or it may be driven in the forward and backward direction using an actuator. Furthermore, the operating wire 80 may be driven with it exposed to the outside of the first hollow shaft 20, or it may be driven without being exposed to the outside of the first hollow shaft 20 (i.e., housed inside the first hollow shaft 20).

[0025] The sealing portion 60 is located in the lumen 51L of the branch portion 59. The sealing portion 60 allows the operation wire 80, guide wire, and microcatheter to be inserted through it, and seals the lumen 51L to maintain airtightness inside the first hollow shaft 20. The sealing portion 60 can be configured, for example, as a valve body. Note that the sealing portion 60 does not need to constantly seal the lumen 51L; it is sufficient that it has a structure that can seal the lumen 51L at least when the suction device is driven (when creating negative pressure inside the first hollow shaft 20).

[0026] (A-2) Thrombectomy procedure: Figures 4 and 5 are explanatory diagrams showing an example of thrombus retrieval operation using the catheter 10 of this embodiment. In Figures 4 and 5, a blood vessel 90 is shown as an example of a biological lumen, and a thrombus 92 is shown as an example of a foreign body. As shown in Figures 4 and 5, a lesion has formed in the blood vessel 90 where the blood vessel 90 is occluded by the thrombus 92. Below, as an example, the case in which the blood vessel 90 in which the thrombus 92 has formed is the internal carotid artery will be described. When performing thrombus retrieval operation using the catheter 10, in addition to the catheter 10, for example, a balloon-equipped guide catheter (not shown) can be used. In this case, for example, a sheath can be inserted into the femoral artery, etc., and the balloon-equipped guide catheter can be placed at the entrance of the internal carotid artery through this sheath. Then, a microcatheter 72 is inserted into the catheter 10 (suction catheter) of this embodiment, and a guide wire 70 is inserted into the microcatheter 72, and the integrated system is passed through the balloon-equipped guide catheter and inserted into the blood vessel. At this time, in the catheter 10, as shown in Figure 1, the tip of the stent 40 is housed in the second hollow shaft 30. By expanding the balloon of the balloon-equipped guide catheter at the entrance of the internal carotid artery, the wobbling of the system, including the catheter 10 that advances further distally from the tip of the balloon-equipped guide catheter, can be suppressed and backed up. Furthermore, if the diameter of the blood vessel 90 into which the catheter 10 is inserted is sufficient and there is no hindrance to the delivery of the catheter 10, the microcatheter 72 may be omitted.

[0027] Figure 4(A) shows the guidewire 70 advancing ahead within the blood vessel 90, and the guidewire 70 being delivered by the operator so that its tip is located distal to the thrombus 92 (lesion). However, the tip of the guidewire 70 may be delivered in front of (proximal to) the thrombus 92. Figure 4(B) shows the state after Figure 4(A) is reached, and the microcatheter 72 is pushed along the guidewire 70 by the operator, and the tip of the microcatheter 72 is delivered in front of (proximal to) the thrombus 92. Figure 4(C) shows the state after Figure 4(B) is reached, and the catheter 10 is advanced along the microcatheter 72 by the operator, and the tip of the catheter 10, the second hollow shaft 30, is delivered until it reaches in front of (proximal to) the thrombus 92. In catheter 10, at the site delivered distal to the tip of the balloon-equipped guide catheter, as shown in Figure 4(C), the first hollow shaft 20, the stent 40, and the second hollow shaft 30 are exposed within the thrombus 92 without being housed in any other components. In Figure 4(C), the guidewire 70 is removed from the microcatheter 72 prior to the delivery of catheter 10 along the microcatheter 72, but the guidewire 70 may not be removed when catheter 10 is delivered.

[0028] Figure 5(A) shows the state after the microcatheter 72 has been removed from the catheter 10 after reaching the state shown in Figure 4(C). Figure 5(B) shows the state after reaching the state shown in Figure 5(A), where the operator manipulates the manipulating wire 80, pushing the manipulating wire 80 and the second hollow shaft 30 distally, causing the second hollow shaft 30 to detach from the tip of the stent 40, and the stent 40 to self-expand. As shown in Figure 5(B), as the stent 40 expands in diameter, the outer peripheral portion 47, which is the tip of the stent 40, comes into contact with the inner wall of the blood vessel 90. At this time, a radially outward force is applied from the outer peripheral portion 47 to the inner wall of the blood vessel 90, and the stent 40 is held in the self-expanded position within the blood vessel 90. As previously described, when the second hollow shaft 30 detaches from the tip of the stent 40, the diameter of the outer circumference 47, which is the tip of the stent 40, becomes larger than the diameter of the first hollow shaft 20. Therefore, the size of the stent 40 provided by the catheter 10 used should be appropriately selected according to the diameter of the blood vessel 90 to be thrombus retrieved. The expansion pressure of the stent 40 (the pressure applied from the stent 40 to the inner wall of the blood vessel 90 when the stent 40 is expanded) can be arbitrarily set by the outer diameter when the stent 40 is expanded without being restricted by the blood vessel, the axial length of the stent 40, or the weaving method and material of the wires 42 that make up the stent 40.

[0029] As previously described, the stent 40 comprises a mesh member and a resin layer 44 covering the mesh member. Therefore, as described above, the stent 40 self-expands within the blood vessel 90, blocking the blood vessel 90 and interrupting the blood flow distal to the vessel 90. The degree to which the stent 40 obstructs blood flow within the blood vessel 90 does not need to be complete, as long as it does not hinder the thrombus 92 retrieval operation described later. However, to improve the efficiency of aspirating and retrieving the thrombus 92, it is desirable that the blood flow be sufficiently blocked.

[0030] Figure 5(C) shows the state after the operating wire 80 and the second hollow shaft 30 have been removed from the stent 40 and the first hollow shaft 20, as shown in Figure 5(B). The second hollow shaft 30 may be completely removed from the first hollow shaft 20 by opening the valve body that constitutes the sealing portion 60, for example, or it may be simply pulled back to the vicinity of the sealing portion 60. In the state shown in Figure 5(C), the operator activates the suction device attached to the connector 50. As a result, the thrombus 92 is drawn into the stent 40, and if the thrombus 92 is smaller than the inner diameter of the first hollow shaft 20, it is drawn into the first hollow shaft 20, guided through the thrombus retrieval lumen (lumen 20L) of the first hollow shaft 20 to the suction device, where it is aspirated and removed. At this time, the stent 40 is held within the blood vessel 90 while pressing the inner wall of the blood vessel 90 radially outward, so that leakage of suction force from between the stent 40 and the inner wall of the blood vessel 90 is suppressed, and the suction of the thrombus 92 can be performed efficiently. In addition, since the stent 40 suppresses blood flow toward the distal side, it is possible to prevent the thrombus 92, which has been detached from the inner wall of the blood vessel 90 by suction, from being propelled distally (peripherally) by the blood flow.

[0031] After the thrombus 92 has been retrieved, the operator removes the catheter 10. At this time, the catheter 10 is pulled back to the entrance of the internal carotid artery, where it is housed within the balloon-tipped guide catheter and removed from the body together with the balloon-tipped guide catheter.

[0032] Furthermore, when performing the procedure to aspirate the thrombus 92 described above, in order to understand how the catheter 10 etc. advances within the blood vessel 90 during the procedure, radiopaque markers may be provided, for example, at the tip of the second hollow shaft 30, the tip of the first hollow shaft 20, the tip of the microcatheter 72, the tip of the guidewire 70, etc. It is also desirable to provide radiopaque markers at the rear end of the second hollow shaft 30 and at the tip of the stent 40. Radiopaque markers can be provided, for example, by constructing the parts of each component where radiopaque markers should be provided from radiopaque material, attaching radiopaque members, or, in the case of resin components, by kneading a radiopaque material into the resin.

[0033] In the catheter 10 of this embodiment, configured as described above, the tip of the self-expanding stent 40, which is joined to the tip of the first hollow shaft 20, is housed in a second hollow shaft 30 which is positioned further forward than the first hollow shaft 20 and has an outer diameter smaller than the inner diameter of the first hollow shaft 20. Therefore, when delivering the catheter 10 within the body, it is not necessary to use a shaft (a shaft with a larger diameter than the first hollow shaft 20) to house the first hollow shaft 20 together with the stent 40 in order to house the reduced-diameter stent 40. In this way, since it is not necessary to house the first hollow shaft 20 in a shaft with a larger diameter than the first hollow shaft 20, the diameter of the first hollow shaft 20 is not limited by the diameter of the other shaft that houses the first hollow shaft 20. Therefore, the diameter of the first hollow shaft 20, which is a suction catheter, can be made larger, thereby increasing the suction capacity when aspirating the thrombus 92.

[0034] Furthermore, with the catheter 10 of this embodiment, the first hollow shaft 20 is not used to house the reduced-diameter stent 40 when delivering the catheter 10 within the body. Therefore, the first hollow shaft 20, which extends distally from the tip of the guide catheter (a balloon-equipped guide catheter in this embodiment) and advances within the blood vessel 90, does not lose flexibility due to housing the self-expandable stent 40 (a member that generates a force pushing radially outward). In this way, by ensuring the flexibility of the first hollow shaft 20, it becomes possible to guide the first hollow shaft 20 more easily, even in curved cerebral blood vessels, for example, and the safety of delivering the first hollow shaft 20 within the blood vessel 90 can be enhanced. In this case, the second hollow shaft 30 that houses the reduced-diameter stent 40 may lose flexibility due to housing the stent 40. However, since the outer diameter of the second hollow shaft 30 is smaller than the inner diameter of the first hollow shaft 20, and the second hollow shaft 30 is provided only in a limited area near the tip of the catheter 10, the impact of the reduced flexibility causing difficulty in delivering the catheter tip can be suppressed. In particular, by constructing the second hollow shaft 30 from a relatively soft material such as resin, as previously described, the impact of reduced flexibility due to housing the stent 40 can be suppressed.

[0035] Furthermore, according to the catheter 10 of this embodiment, the stent 40 comprises a tubular mesh member that can expand and contract radially, and a resin layer 44 covering the mesh member. Therefore, when aspirating the thrombus 92, leakage of suction force through the mesh of the mesh member is suppressed, thereby improving the performance of aspirating the thrombus 92. In addition, the degree to which the stent 40 blocks the blood flow flowing distally within the blood vessel 90 is increased, thereby improving the effect of preventing the thrombus 92, which has been detached from the inner wall of the blood vessel 90 by suction, from being propelled distally (peripherally) by the blood flow.

[0036] Furthermore, according to the catheter 10 of this embodiment, the stent 40 has a bent portion 48 that, when viewed from a direction perpendicular to the central axis of the stent 40 (perpendicular to the axial direction) with the second hollow shaft 30 removed from the tip of the stent 40 and expanded, changes the inclination angle at which the stent 40 expands toward the tip to approach the axial direction. As a result, the angle between the inner wall of the blood vessel 90 and the outer peripheral portion 47 becomes smaller than the angle between the blood vessel 90 and the intermediate portion 46, thereby reducing the possibility of damaging the blood vessel 90 with the tip of the stent 40. In addition, since the change in diameter during expansion is smaller at the outer peripheral portion 47, which is the tip of the stent 40, than at the intermediate portion 46, it becomes easier to contract the stent 40 and house the tip within the second hollow shaft 30.

[0037] B. Second Embodiment: In the first embodiment, the stent 40 of the catheter 10 is provided with a resin layer 44 covering the entire mesh member constituting the stent 40. However, the resin layer 44 may be provided only on a part of the mesh member. For example, the mesh members constituting the constant diameter portion 45 and the intermediate portion 46 at the proximal end may be provided with a resin layer 44, while the mesh members constituting the outer peripheral portion 47 at the tip end may not be provided with a resin layer 44. A configuration with such a stent 240 will be described below as the second embodiment.

[0038] Figure 6 is an explanatory diagram showing the stent 240 of the second embodiment expanded within the blood vessel 90, in the same manner as in Figure 5(C). Of the stent 240, the outer peripheral portion 47 that does not have the resin layer 44 is also called the "uncovered portion". In the stent 240 of the second embodiment, since the outer peripheral portion 47 does not have the resin layer 44, it becomes easier to contract the stent 240 and house the tip of the stent 240 in the second hollow shaft 30. Furthermore, because the outer peripheral portion 47 does not have the resin layer 44, the degree to which the flexibility of the second hollow shaft 30 decreases when the outer peripheral portion 47 is housed can be suppressed. At this time, since the outer peripheral portion 47 is the part that abuts against the inner wall of the blood vessel 90, the absence of the resin layer 44 on the outer peripheral portion 47 can suppress leakage of suction force from the mesh member when aspirating the thrombus 92.

[0039] C. Third Embodiment: Figure 7 is a partial cross-sectional view showing the schematic configuration of the catheter 310 of the third embodiment. The catheter 310 of the third embodiment differs from the first embodiment shown in Figure 1 in that it is equipped with a connector 350 instead of a connector 50.

[0040] Connector 350 has a straight shape, unlike the Y-shaped bifurcated shape of connector 50. Connector 350 comprises a hollow body portion 359 and a fin portion 351. The lumen 51L of the body portion 359 functions as a guidewire lumen and a thrombus lumen. The proximal end portion 20p of the first hollow shaft 20 is joined to the tip portion 59d of the body portion 359. The fin portion 351 is joined to the proximal end portion 359s of the body portion 359. The fin portion 351 has a shape similar to the fin portion 51 of the first embodiment, and the opening 51o on the proximal end side leading to the lumen 51L is configured to allow attachment of a suction device (not shown). The material of the fin portion 351 can be, for example, the same material as the fin portion 51 of the first embodiment.

[0041] When performing a procedure to retrieve the thrombus 92 using the catheter 310 of the third embodiment in the same manner as in Figures 4 and 5, for example, the valve body constituting the sealing portion 60 can be opened to withdraw the guide wire 70, microcatheter 72, and operating wire 80 to which the second hollow shaft 30 is joined from inside the first hollow shaft 20 to the state shown in Figure 5(A), after which a suction device can be connected to the vane portion 351 and the suction operation can be performed. Even with this configuration, the same effects as the first embodiment can be obtained. Furthermore, since the catheter 310 can be constructed using a connector 350 without a branching portion, the catheter 310 can be made smaller. However, when using a connector 350 without a branching portion, it is necessary to connect the suction device after the withdrawal of the guide wire 70 and operating wire 80 as described above, so from the viewpoint of shortening the overall procedure time, it is preferable to use a bifurcated connector 50 as in the first embodiment.

[0042] D. Other embodiments: In the embodiments described above, the stent, which is a self-expanding member, comprises a mesh member and a resin layer 44 covering the mesh member, but a different configuration is also possible. For example, if the mesh of the mesh member is relatively fine and the effect of blocking blood flow distally within the blood vessel 90 can be sufficiently obtained with the mesh member alone, the resin layer 44 covering the mesh member may be omitted. Alternatively, the self-expanding member may be formed in an umbrella shape comprising a plurality of metal bone portions that can self-expand outward toward the tip with respect to the central axis of the first hollow shaft 20, and a resin membrane stretched over these bone portions. It may also be a self-expandable funnel-shaped member made of resin or metal. The self-expanding member only needs to be able to be folded in a self-expandable manner so that its tip can be stored inside the second hollow shaft 30.

[0043] Although the catheters in each of the embodiments described above are suction catheters for thrombus retrieval, they can be broadly applied to catheters that remove foreign bodies from tubular lumenes by suction while obstructing the flow within the lumen of the body. For example, they can be used as devices to remove objects (foreign bodies) from tubular lumenes of the body, such as cerebral blood vessels, other vascular systems such as the heart, lymphatic system, biliary system, urinary tract system, respiratory system, digestive system, secretory glands, and reproductive organs.

[0044] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-mentioned problems, or to achieve some or all of the above-mentioned effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of Symbols]

[0045] 10,310…Catheter 20…First hollow shaft 20L…lumen 20d...Tip 20p…Proximal end 30…Second hollow shaft 31…Joint part 40,240…stent 40p…Proximal end 42... Strand wire 44… Resin layer 45... Diameter-fixed section 46...Middle section 47…Outer perimeter 48...Bend 50,350… connectors 51,351... Feather section 51L…Inner cavity 51o…opening 52...Wing section 52L…lumen 52o…opening 59... Branching point 59b...Second base 59d...Tip 59s...First proximal end 60... Sealing part 70… Guidewire 72... Microcatheter 80... Operating wire 90...Vessel 92...thrombus 359...Main body 359s…Proximal end

Claims

1. It is a catheter, First hollow shaft and A self-expanding member comprising a cylindrical mesh member that can expand and contract radially, and a resin layer covering the mesh member, with the rear end joined to the tip side of the first hollow shaft, the tip portion of which is self-expanding radially, A second hollow shaft having an outer diameter smaller than the inner diameter of the first hollow shaft, housing the tip of the self-expanding member in a radially contracted state, The tip is joined to the second hollow shaft, and the portion of the linear member extending inside the second hollow shaft, the self-expanding member, and the first hollow shaft is located further back than the portion joined to the second hollow shaft. Equipped with, When the catheter is inserted into the body, the tip of the self-expanding member is housed in the second hollow shaft, and a portion of the self-expanding member, including the tip, protrudes from the tip of the first hollow shaft. The self-expanding member is When the tip of the self-expanding member is housed in the second hollow shaft, the self-expanding member has a shape such that the overall outer diameter is smaller than the outer diameter of the first hollow shaft. When a force is applied to the linear member from the rear end to the front end of the first hollow shaft, the second hollow shaft moves together with the linear member, causing the second hollow shaft to detach from the front end of the self-expanding member, and the self-expanding member expands radially until its outer diameter becomes larger than the outer diameter of the first hollow shaft. catheter.

2. A catheter according to claim 1, The self-expanding member comprises a fixed diameter portion at the base end, an outer peripheral portion at the tip end, and an intermediate portion which is the portion between the fixed diameter portion and the outer peripheral portion. The aforementioned intermediate portion has a shape that gradually decreases in diameter from the constant diameter portion toward the outer circumference when the outer circumference is housed in the second hollow shaft. catheter.

3. A catheter according to claim 1 or 2, The linear member is joined to the second hollow shaft at a joint provided at the tip of the second hollow shaft. The joint is located on the tip side of the position of the tip of the self-expanding member when the tip of the self-expanding member is housed within the second hollow shaft. catheter.

4. A catheter according to any one of claims 1 to 3, The self-expanding member has a bent portion such that, when viewed from a direction perpendicular to the central axis of the self-expanding member with the second hollow shaft removed from the tip of the self-expanding member, the angle of inclination in which the self-expanding member expands toward the tip is changed to approach the axial direction. catheter.

5. A catheter according to any one of claims 1 to 4, The self-expanding member has an uncoated portion at its tip that does not have the resin layer, and when the tip of the self-expanding member is housed in the second hollow shaft, the uncoated portion is housed in the second hollow shaft. catheter.

6. A catheter according to any one of claims 1 to 5, a connector to which the rear end of the first hollow shaft is connected, and a suction device connected to the first hollow shaft via the connector. Suction device.

Images