JP7843128B2 - Catheters and suction devices - Google Patents

Description

This disclosure relates to catheters and suction devices.

As a device used in endovascular treatment, such as for the treatment of cerebral infarction, a device equipped 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 to the diameter of the blood vessel. By expanding the funnel, the blood vessel is closed and blood flow is blocked, and then the thrombus is aspirated using the suction catheter. Furthermore, the above device is equipped with a delivery catheter to guide the funnel to the vicinity of the lesion. Until the funnel is guided to the vicinity of the lesion and expands, it is housed within the delivery catheter along with the suction catheter, thus suppressing its expansion.

Special Publication No. 2018-501038

Such devices house the funnel at the tip of the suction catheter within the delivery catheter, requiring the outer diameter of the suction catheter to 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 above-mentioned devices, the diameter of the suction catheter is limited by the delivery catheter. Therefore, to improve the efficiency of thrombus retrieval, it was desirable to further increase the suction force of the suction catheter. Furthermore, in the above-mentioned devices, there was a problem where the flexibility of the delivery catheter decreased due to the force applied in the direction of funnel expansion. Reduced flexibility of the delivery catheter can make it difficult to guide the tip of the delivery catheter to the desired location (lesion site) within the curved cerebral blood vessels; therefore, a technology to ensure the flexibility of the delivery catheter was desired. These challenges are common to all devices that remove foreign bodies from the luminal systems of living organisms, including the vascular system, lymphatic system, biliary system, urinary tract system, airway system, digestive system, secretory glands, and reproductive organs.

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 configuration, 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 self-expanding member along with the first hollow shaft in order to house the self-expanding member after it has been reduced in diameter. Thus, since the first hollow shaft does not need to be housed within a shaft with a larger diameter than the first hollow shaft, 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, thereby increasing its suction capacity when the first hollow shaft is 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.

A partial cross-sectional view showing the schematic configuration of the catheter according to the first embodiment. Schematic cross-sectional view of section A-A in Figure 1. A schematic diagram illustrating how the stent deforms in response to manipulation of the operating wire. An explanatory diagram showing an example of the procedure for thrombus retrieval using a catheter. An explanatory diagram showing an example of the procedure for thrombus retrieval using a catheter. An explanatory diagram showing how the stent of the second embodiment expands within a blood vessel. A partial cross-sectional view showing the schematic configuration of the catheter according to the third embodiment.

A. First embodiment:
(A-1) Overall structure of the catheter:
Figure 1 is a partial cross-sectional view showing the schematic configuration of a catheter 10 according to 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.

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 at the proximal end 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, while the proximal end corresponds to the "proximal end," which is manipulated by the surgeon, such as a physician.

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 an internal lumen 20L. 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 via 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. Furthermore, a connector 50 is 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.

The first hollow shaft 20 preferably possesses 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.

The stent 40 is a hollow, cylindrical member that is radially expandable and contractible, with open ends (tip and base), and comprises a mesh member formed by weaving strands. Figure 1 shows the stent 40 in a contracted state. While the stent 40 includes a mesh member, in Figure 1 and Figures 3 to 5 (described later), the stent 40 is shown only by lines representing its outer circumference to simplify its shape 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, joining with an adhesive such as epoxy adhesive, or joining with metal solder such as silver solder, gold solder, zinc, Sn-Ag alloy, or Au-Sn alloy can be employed.

The stent 40 is radially expandable and contractible. When the catheter 10 is inserted into the body, the tip of the stent 40 folds and is stored within the second hollow shaft 30 in a radially contracted state, as shown in Figure 1 (the state in Figure 1). Furthermore, the stent 40 is 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 referred to as a "self-expanding member."

Figure 2 is a schematic cross-sectional view of the section A-A shown in Figure 1. The stent 40 comprises a mesh member formed by weaving multiple 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 using a double strand, 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, while the remaining strands 42 are double strands.

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. Additionally, 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.

Furthermore, the stent 40 includes a resin layer 44 made of resin that covers the mesh member constituting the stent 40. In the stent 40 of this embodiment, the resin layer 44 is formed to cover the entire mesh member. By providing the resin layer 44, the gaps between the wires 42 in the mesh member are sealed. However, the gaps between the wires 42 in the mesh member do not need to be completely sealed. As the resin constituting the resin layer 44, for example, polyurethane, polytetrafluoroethylene (PTFE), silicone resin, etc., can be used. The resin layer 44 can be formed, for example, by dipping the mesh member in a bath of molten resin and then drying it with hot air.

Returning to Figure 1, the second hollow shaft 30 is positioned at the tip of the catheter 10 and is a component that advances through the blood vessel ahead of other components. The second hollow shaft 30 extends along the axis O and has a roughly cylindrical shape with open ends (tip and proximal end). The outer diameter of the second hollow shaft 30 is smaller than the inner diameter of the first hollow shaft 20. Since the second hollow shaft 30 advances through the blood vessel ahead of other components and contacts the inner wall of the blood vessel before other components, it is desirable to form it from a relatively soft material, for example, from 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 of the stent 40. If sufficient flexibility can be 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. Furthermore, the tip of the second hollow shaft 30 may be equipped with a component (for example, a urethane chip) made of a softer material than the rest of the second hollow shaft 30.

The operating wire 80 has its tip joined to the second hollow shaft 30 at a joint 31 located at the tip of the second hollow shaft 30. The portion of the operating wire 80 proximal to the joint 31 extends inside the second hollow shaft 30, the stent 40, and the first hollow shaft 20. The joint 31 is located on the second hollow shaft 30, further to the tip than the position of the stent 40's tip when it is housed within the second hollow shaft 30. In the catheter 10 of this embodiment, when the operating wire 80 is moved toward the tip relative to the stent 40 and the first hollow shaft 20, the second hollow shaft 30 also moves toward the tip relative to the stent 40 along with the operating wire 80, causing the second hollow shaft 30 to detach from the tip of the stent 40 in the state shown in Figure 1. The operating wire 80 is also referred to as a "linear member."

The operating wire 80 only needs to have enough rigidity to allow the second hollow shaft 30 to move axially when the operating wire 80 is moved axially while it is joined to the second hollow shaft 30 at the joint 31. The operating wire 80 can be made of a metallic material such as stainless steel (e.g., SUS304), nickel-titanium alloy, cobalt-chromium alloy, or tungsten alloy. Furthermore, the linear member configured as the operating wire 80 in this embodiment may not be wire-shaped; for example, at least a portion of it may be composed of a tubular member or a rod-shaped member.

The joining of the operating wire 80 and the second hollow shaft 30 at the joint 31 can be achieved by any method; for example, it can be done using an adhesive such as an epoxy adhesive. Alternatively, if at least the portion of the second hollow shaft 30 including the area where the joint 31 is formed is made of metal, the joining may be done by welding, brazing, or soldering.

Figure 3 is a schematic diagram illustrating how the stent 40 is deformed when the operating wire 80 is operated during the use of the catheter 10, causing the operating wire 80 and the second hollow shaft 30 to move. 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, 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 within 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 within 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 within 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. That is, when viewing the tip of the catheter 10, including the tip of the first hollow shaft 20, from the axial direction, the outer circumference of the stent 40 is located inside the outer circumference of the first hollow shaft 20.

Figure 3(B) shows the result of the second hollow shaft 30 detaching from the tip of the stent 40 and self-expanding as a result of the force applied to the operating wire 80 toward the tip as described above. 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 base end to the operating wire 80 in this state is indicated by a white arrow. Figure 3(C) shows the result of the operating wire 80 and the second hollow shaft 30 being pulled out through the interior of the stent 40 and the first hollow shaft 20 as a result of the force applied to the operating wire 80 toward the base end as described above.

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 gradually expand 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 intermediate portion 46 gradually expands in diameter from the constant-diameter portion 45 towards the outer circumference 47. Therefore, the boundary between the intermediate portion 46 and the outer circumference 47 is a bent portion 48, as shown in Figure 3(C), where, when viewing the stent 40 from a direction perpendicular to the central axis (perpendicular to the axial direction), the angle of inclination for expansion towards the tip is changed to approach the axial direction.

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.

The blade portion 51 has a hollow shape with open ends (tip and base), and the operating wire 80 described above is exposed from the base end opening 51o that leads to the lumen 51L. The blade portion 52 has a hollow shape with open ends (tip and base) similar to the blade portion 51, and the base end opening 52o that leads to the lumen 52L is configured to allow the attachment of a suction device (not shown). Any shape can be adopted for the blade portions 51 and 52. Also, the blade portions 51 and 52 may be omitted. The branch portion 59, the blade portion 51, and the blade portion 52 can be formed from 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 component attached to the catheter 10 and converting that rotational motion into linear motion. Alternatively, 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).

The sealing portion 60 is positioned in the lumen 51L of the branching portion 59. The sealing portion 60 allows for the insertion of the operating wire 80, guide wire, and microcatheter, 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 only needs to have 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).

(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.

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 second hollow shaft 30, which is the tip of the catheter 10, is delivered until it reaches in front of (proximal to) the thrombus 92. In catheter 10, at the portion 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. Note that in Figure 4(C), the guidewire 70 is removed from the microcatheter 72 prior to the delivery of catheter 10 along the microcatheter 72; however, the guidewire 70 may not be removed when catheter 10 is delivered.

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 operating wire 80, pushing the operating 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 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 restriction 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.

As described above, 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 distally within it. 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 blood flow be sufficiently blocked.

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, following the state 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. In this case, the stent 40 is held within the blood vessel 90 while pressing radially outward against the inner wall of the blood vessel 90. This prevents leakage of suction force between the stent 40 and the inner wall of the blood vessel 90, allowing for efficient suction of the thrombus 92. Furthermore, because the stent 40 restricts distal blood flow, it prevents the thrombus 92, detached from the inner wall of the blood vessel 90 by suction, from being propelled distally (peripherally) by blood flow.

After retrieving the thrombus 92, the operator removes the catheter 10. At this point, the catheter 10 is withdrawn to the entrance of the internal carotid artery, then retracted into the balloon-tipped guide catheter, and removed from the body together with the balloon-tipped guide catheter.

Furthermore, when performing the procedure to aspirate the thrombus 92 described above, in order to understand how the catheter 10 etc. is progressing within the blood vessel 90 during the procedure, radiopaque markers may be provided on, for example, 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 on the rear end of the second hollow shaft 30 and the tip of the stent 40. Radiopaque markers can be provided, for example, by constructing the areas where radiopaque markers should be provided on each of the above-mentioned components from radiopaque material, attaching radiopaque components, or, in the case of resin components, by kneading a radiopaque material into the resin.

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 within 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 separate shaft (a shaft with a larger diameter than the first hollow shaft 20) to house the stent 40 together with the first hollow shaft 20 in order to accommodate the reduced-diameter stent 40. Thus, since the first hollow shaft 20 does not need to be housed within a shaft with a larger diameter, the diameter of the first hollow shaft 20 is not limited by the diameter of the other shafts that house it. Therefore, the diameter of the first hollow shaft 20, which is the suction catheter, can be made larger, thereby increasing the suction capacity when aspirating the thrombus 92.

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 suffer a decrease in 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 configuration, the second hollow shaft 30, which houses the reduced-diameter stent 40, may experience a decrease in flexibility due to the stent 40's presence. 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 difficulties in catheter tip delivery can be minimized. In particular, by constructing the second hollow shaft 30 from a relatively soft material such as resin, as described above, the impact of reduced flexibility due to the stent 40's presence can be further reduced.

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 this 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. Also, because the degree to which the stent 40 blocks blood flow distally within the blood vessel 90 is increased, 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 blood flow is enhanced.

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. Therefore, 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. Also, because the change in diameter during expansion is smaller at the outer peripheral portion 47 (the tip of the stent 40) than at the intermediate portion 46, the operation of contracting the stent 40 and housing the tip within the second hollow shaft 30 becomes easier.

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 fixed 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.

Figure 6 is an explanatory diagram showing the stent 240 of the second embodiment expanded within the blood vessel 90, similar to Figure 5(C). The outer peripheral portion 47 of the stent 240, which 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, the operation of contracting the stent 240 and housing the tip of the stent 240 in the second hollow shaft 30 becomes easier. 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 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.

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.

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 base end 20p of the first hollow shaft 20 is joined to the tip 59d of the body portion 359. The fin portion 351 is joined to the base end 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 base end side, which leads to the lumen 51L, is configured to allow the 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.

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, and the guide wire 70, microcatheter 72, and operating wire 80 to which the second hollow shaft 30 is joined can be withdrawn from the first hollow shaft 20 to the state shown in Figure 5(A). Then, a suction device can be connected to the wing 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 miniaturized. 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, etc., as described above. Therefore, from the viewpoint of shortening the overall procedure time, it is preferable to use a bifurcated connector 50 as in the first embodiment.

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.

The catheters in each of the embodiments described above are suction catheters for thrombus retrieval, but 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 the cerebral blood vessels, other vascular systems like the heart, lymphatic system, biliary system, urinary tract system, respiratory system, digestive system, secretory glands, and reproductive organs.

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 appropriately replaced or combined 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 appropriately deleted.

10,310...Catheter 20...First hollow shaft 20L...Lumen 20d...Tip 20p...Proximal end 30...Second hollow shaft 31...Joint 40,240...Stent 40p...Proximal end 42...Wire 44...Resin layer 45...Regular diameter section 46...Middle section 47...Outer circumference 48...Bent section 50,350...Connector 51,351...Wing section 51L...Lumen 51o...Opening 52...Wing section 52L...Lumen 52o...Opening 59...Branching section 59b...Second proximal end 59d...Tip 59s...First proximal end 60...Sealing section 70...Guidewire 72...Microcatheter 80...Manipulating wire 90...Blood vessel 92...Thrombosis 359...Main body 359s...Proximal end

Claims (6)

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.
A catheter in which, 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, 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. 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 fixed-diameter portion toward the outer circumference when the outer circumference is housed in the second hollow shaft. 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. A catheter according to any one of claims 1 to 3,
The self-expanding member is a catheter having 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 inclination angle at which the self-expanding member expands toward the tip is changed to approach the axial direction. 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. A suction device comprising: 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.