Introducer sheath, hub, and system

Abstract

This introducer sheath 30 is used in work for inserting a medical instrument accommodated on a distal end side into a microcatheter via a hub provided at a proximal end part of the microcatheter, wherein a distal end part 31 of the introducer sheath 30 includes a portion in which the outer profile of a cross section orthogonal to the central axis direction has a non-circular shape.

Description

Introducer sheaths, hubs and systems

[0001] The present invention relates to introducer sheaths, hubs and systems.

[0002] Conventionally, an introducer sheath has been used as a medical device for inserting a stent for thrombus retrieval into a microcatheter. The stent is transferred from the introducer sheath to the microcatheter by abutting the distal end of the introducer sheath against the inner surface of the flow channel of a hub connected to the proximal end of the microcatheter. Prior to this abutment, a procedure is performed (hereinafter also referred to as "flushing") in which saline is introduced through a gap between the inner surface of the flow channel of the hub and the introducer sheath to make the introducer sheath liquid-tight and expel any air. This is because flushing, performed with the inner surface of the flow channel of the hub abutting against the distal end of the introducer sheath, makes it difficult to expel any air remaining in the introducer sheath.

[0003] In medical settings, there have been cases where practitioners have pushed the stent into the microcatheter without abutting the two together after flushing, leaving a gap between the inner surface of the hub's flow path and the introducer sheath. If the stent is pushed out of the introducer sheath without the two being abutted, the stent may expand in diameter, making it impossible to insert the stent into the microcatheter or being inserted into the microcatheter in a deformed state. In response to this, a stent delivery device has been proposed that has a gas-permeable annular portion between the rear end of the microcatheter and the hub (see Patent Document 1).

[0004] Patent No. 6001946

[0005] In the stent delivery device of Patent Document 1, when flushing is performed, air remaining in the introducer sheath is expelled to the outside through the gas-permeable annular portion by the hydraulic pressure of the saline solution. Furthermore, as a prior art that achieves a similar effect, an introducer sheath provided with a purge hole at the tip for expelling air has been proposed.

[0006] The stent delivery device of Patent Document 1 is likely to have air remaining inside the introducer sheath depending on the hydraulic pressure of the saline solution. Furthermore, introducer sheaths with purge holes at their distal ends require specialized equipment to form the purge holes, and there is a risk that debris generated during purge hole processing may remain in the purge holes. Furthermore, if the purge holes are not formed in an appropriate shape, air may remain in the purge holes during flushing. Therefore, there is a need for a method that allows air to be more reliably expelled during flushing when the hub and introducer sheath are butted together from the beginning.

[0007] An object of the present invention is to provide an introducer sheath, a hub, and a system that can more reliably expel air when flushing in a state where the hub is initially abutting against the inner surface of the flow path.

[0008] The first invention relates to an introducer sheath used in inserting a medical instrument housed on the distal side into a microcatheter via a hub provided at the proximal end of the microcatheter, wherein the distal end of the introducer sheath includes a portion whose outer shape in a cross section perpendicular to the central axis is non-circular.The second invention relates to an introducer sheath used in inserting a medical instrument housed on the distal side into the microcatheter via a hub provided at the proximal end of the microcatheter, wherein the outer shape of the distal end surface of the introducer sheath differs from the shape of the cross section perpendicular to the central axis of the tubular channel at the abutment position between the introducer sheath and a tubular channel formed in the hub. A third invention relates to an introducer sheath used in inserting a medical instrument housed at the distal end into a microcatheter via a hub provided at the proximal end of the microcatheter, the introducer sheath having a liquid circulation portion on the outer periphery of the distal end, the liquid circulation portion having a shape that does not come into contact with the inner surface of a conical cylindrical flow path formed in the hub when the introducer sheath is abutted against the conical cylindrical flow path, and that forms a gap that serves as a liquid circulation path between the introducer sheath and the inner surface of the conical cylindrical flow path.

[0009] In the introducer sheath according to the third aspect of the present invention, the liquid circulation portion may be provided at a position on the end surface of the distal end side of the introducer sheath that does not overlap with the opening hole.

[0010] In the introducer sheath according to the third aspect of the present invention, the liquid circulation portion may be an inclined surface provided on an outer periphery of the distal end portion of the introducer sheath.

[0011] In the introducer sheath according to the third aspect of the present invention, the liquid circulation portion may be a groove provided on an outer periphery of the distal end portion of the introducer sheath.

[0012] In the introducer sheath according to the above invention, the distal end portion of the introducer sheath may have a conical shape with an outer diameter gradually decreasing from the rear end side toward the distal end side.

[0013] In the introducer sheath according to the above invention, the distal end portion of the introducer sheath may be cylindrical.

[0014] In the introducer sheath according to the above invention, at least the distal end portion of the introducer sheath may be translucent.

[0015] A fourth invention relates to a hub that is provided at the base end of a microcatheter and against which the tip of an introducer sheath containing a medical instrument is abutted during the operation of inserting a medical instrument into the microcatheter, wherein at least a portion of a cylindrical flow path that communicates with the rear end of the microcatheter and against which the tip of the introducer sheath abuts has an abutment portion that has a non-circular cross section perpendicular to the central axis and whose cross-sectional area gradually increases from the tip side to the rear end side.

[0016] In the hub according to the fourth aspect of the present invention, the cross section of the abutting portion perpendicular to the central axis direction may have an n-sided polygon (n≧3).

[0017] In the hub according to the fourth aspect of the present invention, the cross section of the abutment portion perpendicular to the central axis direction may be elliptical.

[0018] A fifth invention relates to a system including a medical device and an introducer sheath housing the medical device at its distal end, wherein the outer shape of the distal end surface of the introducer sheath at a position where the introducer sheath abuts against a tubular channel formed in a hub provided at the proximal end of a microcatheter differs from the shape of a cross section perpendicular to the central axis of the tubular channel, and the system is used to insert the medical device from the proximal end of the microcatheter after abutting the distal end of the introducer sheath against the tubular channel of the hub and making the interior liquid-tight with a liquid introduced through a gap formed between the distal end of the introducer sheath and the inner surface of the tubular channel. In the system according to the fifth invention, the length between the distal end surface of the introducer sheath and the proximal end of the microcatheter may be greater than 0 mm and less than or equal to 10 mm at the position where the distal end of the introducer sheath abuts against the tubular channel of the hub.

[0019] The introducer sheath, hub, and system according to the present invention can more reliably expel air when flushing in a state where the hub is initially abutting against the inner surface of the flow path.

[0020] 3A ; FIG. 4A is a diagram showing the configuration of the catheter stent system 1 of the first embodiment. FIG. 4B is a perspective view showing the shape of the distal end 31 of the introducer sheath 30. FIG. 4C is a side view when viewed from the Y direction of FIG. 2A. FIG. 4B is a schematic cross-sectional view showing the state in which the distal end 31 of the introducer sheath 30 is abutted against the inner surface of the flow channel of the hub 21. FIG. 4C is a cross-sectional view taken along s1-s1 of FIG. 3A. FIG. 4C is a schematic cross-sectional view showing the state in which a general introducer sheath 130 is abutted against the inner surface of the flow channel of the hub 21. FIG. 4D is a cross-sectional view taken along s2-s2 of FIG. 4A. FIG. 4D is a schematic view showing the procedure for inserting a stent into the microcatheter 10 from the introducer sheath 30. FIG. 4E is a schematic view showing the procedure for inserting a stent into the microcatheter 10 from the introducer sheath 30. FIG. 4F is a schematic view showing the procedure for inserting a stent into the microcatheter 10 from the introducer sheath 30. FIG. 4G is a perspective view showing another shape of the distal end 31 of the introducer sheath 30. 6A is a side view when viewed from the Y direction. FIG. 6B is a perspective view showing the configuration of the hub 121 of the second embodiment. FIG. 6C is a schematic cross-sectional view of the hub 121 of the second embodiment. FIG. 8 is a cross-sectional view taken along line s3-s3 of FIG. 8. FIG. 8D is a perspective view showing the shape of the distal end portion 31 of the introducer sheath 30 in a deformed form. FIG. 8E is a perspective view showing the shape of the distal end portion 31 of the introducer sheath 30 in a deformed form. FIG. 8F is a perspective view showing the shape of the distal end portion 31 of the introducer sheath 30 in a deformed form. FIG. 8G is a perspective view showing the shape of the distal end portion 31 of the introducer sheath 30 in a deformed form. FIG. 8H is a perspective view showing the shape of the distal end portion 31 of the introducer sheath 30 in a deformed form. FIG. 8I is a cross-sectional view showing the shape of the cylindrical channel 123 in a deformed form. FIG. 8I is a cross-sectional view showing the shape of the cylindrical channel 123 in a deformed form.

[0021] Hereinafter, embodiments of an introducer sheath and a hub according to the present invention will be described. The drawings attached to this specification are all schematic diagrams, and the shape, scale, aspect ratio, and other aspects of each part have been modified or exaggerated from the actual product for ease of understanding. In the drawings, hatching indicating cross sections of components is omitted as appropriate. On the other hand, hatching is applied to parts that do not represent cross sections of components as appropriate for ease of understanding. In this specification, terms specifying shape, geometric conditions, and the degree of these, such as "orthogonal" and "direction," include not only the strict meaning of the terms but also a range that can be considered to be nearly orthogonal or a range that can be considered to be roughly that direction. Furthermore, in this specification, the direction parallel to the central axis (not shown) of the introducer sheath 30 when it is extended linearly is also referred to as the central axis direction X. In the central axis direction X, the proximal side (described below) closer to the practitioner is referred to as the X1 side, and the distal side (described below) farther from the practitioner is referred to as the X2 side.

[0022] First Embodiment First, an embodiment of an introducer sheath according to the present invention will be described. FIG. 1 is a diagram showing the configuration of a catheter stent system 1 according to the first embodiment. FIG. 2A is a perspective view showing the shape of a distal end portion 31 of an introducer sheath 30. FIG. 2B is a side view of FIG. 2A as viewed from the Y direction. As shown in FIG. 1, the catheter stent system 1 includes a microcatheter 10, a hub assembly 20, and an introducer sheath 30. The catheter stent system 1 shown in FIG. 1 is used, for example, in a procedure to retrieve a thrombus generated in a cerebral blood vessel using a stent 40 (described below), which is an example of a medical device. In this specification, the side of the microcatheter 10 that is inserted into a biological lumen is referred to as the distal side or distal side, and the side opposite the distal side (the right side of the drawing) is referred to as the base end side, proximal side, or rear end side. In addition, in the description of the embodiments, the distal end refers to a certain range including the distal end (the most distal end) and its surroundings, and the proximal end refers to a certain range including the proximal end (the most proximal end) and its surroundings.

[0023] The microcatheter 10 is an elongated cylindrical tube that is inserted into a blood vessel. The microcatheter 10 generally has a core, a spiral coil, covered with a resin layer, and is flexible overall. A stent 40 is inserted into the microcatheter 10 in a contracted state by an introducer sheath 30 (described later). The rear end (X1 side) of the microcatheter 10 is connected to a hub 21 (described later). A protector 11 is fitted over the connection between the microcatheter 10 and the hub 21.

[0024] The hub-equipped Y connector 20 is an assembly component for inserting a stent 40 into the microcatheter 10. The hub-equipped Y connector 20 includes a hub 21 and a hemostatic valve-equipped Y connector (hereinafter also referred to as the "Y connector") 22. The hub 21 is a device having a conical-cylindrical channel 23 (see FIG. 3A ) formed therein, which will be described later. The distal end (X2 side) of the hub 21 is connected to the microcatheter 10. The introducer sheath 30 is inserted into the hub 21 from its rear end via a first port 24 (described later) of the Y connector 22. The distal end 31 (described later) of the introducer sheath 30 inserted into the hub 21 is abutted against the inner surface of the distal end of the conical-cylindrical channel 23, and flushing is performed in this state. The hub 21 is primarily made of a transparent resin so that the amount of saline solution introduced, the presence or absence of remaining air (air bubbles), the position of the distal end 31 of the introducer sheath 30, etc. can be confirmed.

[0025] The hub 21 of this embodiment conforms to the JIS T3268:2018 standard for hubs used in single-use sterilized intravascular catheters. Specifically, the hub 21 of this embodiment conforms to the provisions of ISO 80369-7, Figure B.2 (Table B.2) or Figure B.5 (Table B.5). The introducer sheath 30 of this embodiment is an introducer sheath that conforms to the JIS standard hub.

[0026] The Y connector 22 is an instrument for inserting the introducer sheath 30 and introducing physiological saline. The Y connector 22 is branched into a substantially Y shape, with a first port 24 provided at one end and a second port 25 provided at the other end. The first port 24 serves as an insertion port for the introducer sheath 30. The second port 25 serves as an introduction port for physiological saline. Although not shown, the internal flow paths of the first port 24 and the second port 25 communicate with each other inside the Y connector 22. The distal end of the Y connector 22 is connected to the proximal end of the hub 21 via a connector 26. Note that a hemostatic valve in the Y connector 22 is not shown in FIG. 1 .

[0027] The introducer sheath 30 is an elongated cylindrical tube used when inserting a stent 40 into the microcatheter 10. As shown in FIGS. 2A and 2B , the distal end 31 of the introducer sheath 30 is formed in a conical shape with an outer diameter gradually decreasing from the proximal end (X1 side) to the distal end (X2 side). That is, the distal end 31 of the introducer sheath 30 is formed in a tapered shape that narrows toward the distal end. The introducer sheath 30 also includes a liquid circulation portion 32 on the outer periphery of the distal end 31. The liquid circulation portion 32 has a shape that does not contact the inner surface of the conical cylindrical flow path 23 when the liquid circulation portion 32 is abutted against the conical cylindrical flow path 23 formed in the hub 21, and forms a gap (e.g., gap g1 described below) between the liquid circulation portion 32 and the inner surface of the conical cylindrical flow path 23, which serves as a liquid flow path.

[0028] As described above, the introducer sheath 30 of this embodiment is provided with the fluid circulation portion 32 on the outer periphery of the distal end portion 31, and therefore the outer shape of the distal end surface 33 is non-circular, as shown in Fig. 2A. Note that in a configuration in which the fluid circulation portion 32 is not provided on the outer periphery of the distal end portion 31, the outer shape of the distal end surface is circular. If the circular shape in this case is, for example, a perfect circle, the outer shape of the distal end surface of the introducer sheath 30 of this embodiment will be non-circular.

[0029] In this embodiment, the liquid circulation portion 32 is an inclined surface provided on the outer periphery of the distal end portion 31. As shown in Figures 2A and 2B, the liquid circulation portion 32 is provided on the distal end surface 33 of the introducer sheath 30 at a position that does not overlap with the opening 35 of the through-hole 34. That is, in the introducer sheath 30, the opening 35 maintains a circular hole shape. As will be described later, a stent 40 is housed in a contracted diameter state on the distal side of the introducer sheath 30. In this embodiment, the introducer sheath 30 housing the stent 40 constitutes a system used for inserting the stent 40 from the proximal end of the microcatheter 10.

[0030] By providing the liquid circulation section 32 at the tip section 31 of the introducer sheath 30, when the tip section 31 of the introducer sheath 30 is abutted against the inner surface of the flow path of the hub 21, a gap can be formed between the tip section 31 and the conical cylindrical flow path 23. During flushing, which will be described later, physiological saline flows in through this gap, making it possible to make the insides of the microcatheter 10, the hub 21, and the introducer sheath 30 liquid-tight.

[0031] Next, the introducer sheath 30 inserted into the hub 21 will be described. Fig. 3A is a schematic cross-sectional view showing the state in which the distal end 31 of the introducer sheath 30 is abutted against the inner surface of the flow path of the hub 21. Fig. 3B is a cross-sectional view taken along s1-s1 of Fig. 3A. Fig. 4A is a schematic cross-sectional view showing the state in which a general introducer sheath 130 is abutted against the inner surface of the flow path of the hub 21. Fig. 4B is a cross-sectional view taken along s2-s2 of Fig. 4A. Note that Figs. 3A and 4A omit illustration of a stent 40 (described below) housed at the distal end of the introducer sheath 30 (130).

[0032] As shown in FIG. 3A , a conical-tubular flow path 23 is formed inside the hub 21. The conical-tubular flow path 23 is a conical flow path whose inner diameter gradually decreases from the rear end (X1 side) to the distal end (X2 side). As shown in FIG. 3A , when the introducer sheath 30 is inserted into the conical-tubular flow path 23 of the hub 21, the distal end 31 of the introducer sheath 30 abuts against the inner surface of the conical-tubular flow path 23 at a position (abutment position) Xa in the central axial direction X. Position Xa is defined as a position where the stent 40 can be inserted into the microcatheter 10 without expanding its diameter when pushed out from the distal end 31 of the introducer sheath 30. That is, in FIG. 3A , the length L between the rear end of the microcatheter 10 and the distal end 31 of the introducer sheath 30 is defined to be greater than 0 mm (L > 0 mm) and equal to or less than 10 mm. By specifying the length L within the above range, the stent 40 can be inserted into the microcatheter 10 without expanding its diameter when the distal end 31 of the introducer sheath 30 is abutted against the microcatheter 10 at position Xa. The same applies to position Xa shown in FIG. 4A.

[0033] In this embodiment, the outer shape of the distal end surface 33 of the introducer sheath 30 at position Xa where it abuts against the hub 21 differs from the cross-sectional shape (circular shape) perpendicular to the central axis direction X of the conical cylindrical channel 23 formed in the hub 21. Therefore, when the distal end 31 of the introducer sheath 30 abuts against the inner surface of the conical cylindrical channel 23 at position Xa, as shown in Fig. 3B , the distal end 31 of the introducer sheath 30 comes into contact with the inner surface of the conical cylindrical channel 23 in the range of r1 but does not come into contact with the inner surface of the conical cylindrical channel 23 in the range of r2. Therefore, a gap g1 is formed between the liquid circulation portion 32 of the distal end 31 and the inner surface of the conical cylindrical channel 23 in the range of r2. In this way, when the introducer sheath 30 of this embodiment has the tip 31 abutted against the inner surface of the conical cylindrical flow path 23 of the hub 21, a gap g1 that serves as a liquid flow path is formed between the liquid flow section 32 of the tip 31 and the inner surface of the conical cylindrical flow path 23, so that saline can be flowed into the inside of the hub 21 during flushing.

[0034] On the other hand, as shown in Fig. 4A , when a general introducer sheath 130 not provided with a liquid circulation section 32 is inserted, its tip portion 131 abuts against the inner surface of the conical cylindrical channel 23 at position Xa in the central axis direction X. Although not shown, at position Xa, the tip portion 131 of the introducer sheath 130 makes contact with the inner surface of the conical cylindrical channel 23 of the hub 21 without any gaps. In other words, when a general introducer sheath 130 is inserted, the conical cylindrical channel 23 is blocked by the tip portion 131 of the introducer sheath 130. Therefore, during flushing, the tip portion 131 of the introducer sheath 130 is moved to position Xb, as shown in Fig. 4A . When the tip 131 of the introducer sheath 130 is moved to position Xb, as shown in Figure 4B, a gap g2 is formed between the tip 131 of the introducer sheath 130 and the inner surface of the conical cylindrical flow path 23 of the hub 21, allowing saline to flow into the inside of the hub 21 during flushing.

[0035] As shown in FIG. 4A , in a typical introducer sheath 130, flushing can be performed by providing a gap g2 between the inner surface of the flow channel of the hub 21 and the introducer sheath 130 (position Xb). After flushing, the distal end 131 of the introducer sheath 130 must be abutted against the inner surface of the conical-tubular flow channel 23 of the hub 21. However, if a stent (not shown) is accidentally pushed out of the introducer sheath 130 after flushing without abutting the distal end 131 of the introducer sheath 130 against the inner surface of the flow channel of the hub 21, the stent may expand in diameter, making it impossible to insert into the microcatheter 10 or causing deformation of the stent. As described below, the introducer sheath 30 of this embodiment can perform flushing while the distal end 31 of the introducer sheath 30 abuts against the inner surface of the flow channel of the hub 21, thereby preventing the occurrence of the above-mentioned problems.

[0036] Next, a procedure for inserting the stent 40 into the microcatheter 10 from the introducer sheath 30 will be described. Figures 5A to 5D are schematic diagrams showing the procedure for inserting the stent 40 into the microcatheter 10 from the introducer sheath 30. Figures 5A to 5D illustrate parts of the microcatheter 10, the conical-cylindrical flow path 23 (hub 21), the introducer sheath 30, etc. In addition, in Figures 5B to 5D, the stent 40 is illustrated by solid lines.

[0037] First, as shown in Figure 5A, a guidewire 50 is inserted into the microcatheter 10, and the tip of the guidewire 50 is advanced distally into the blood vessel to guide the microcatheter 10 to the location of the thrombus. The guidewire 50 is a long, thin wire-like member used to guide the microcatheter 10 to the target site in the blood vessel. The guidewire 50 is inserted from the first port 24 (see Figure 1) of the Y connector 22. After the tip of the microcatheter 10 has been guided to the location of the thrombus, the guidewire 50 is withdrawn from the microcatheter 10.

[0038] Next, as shown in Fig. 5B , the introducer sheath 30 is inserted and the tip 31 is brought into abutment against the inner surface of the conical cylindrical channel 23 of the hub 21. The position where the tip 31 of the introducer sheath 30 abuts against the inner surface of the conical cylindrical channel 23 is position Xa shown in Fig. 3A . After the guidewire 50 is withdrawn, the introducer sheath 30 is inserted through the first port 24 of the hub-equipped Y connector 20. A diameter-reduced stent 40 is housed in the tip 31 of the introducer sheath 30. Although not shown, a pusher wire 60 (described below) is connected to the rear end side (X1 side) of the stent 40.

[0039] Next, as shown in FIG. 5C , saline solution S is introduced into the conical cylindrical channel 23. The saline solution S is supplied from the second port 25 (see FIG. 1 ) of the Y connector 22. When the saline solution S is introduced into the conical cylindrical channel 23, the saline solution S flows into the gap g1 ( FIG. 3B ) between the liquid flow section 32 of the introducer sheath 30 and the inner surface of the conical cylindrical channel 23. The inflow of the saline solution S makes the microcatheter 10, the conical cylindrical channel 23 (hub 21), and the inside of the introducer sheath 30 liquid-tight. As a result, air remaining in each of the above sections is expelled to the outside (proximal side) mainly through the through-hole 34 of the introducer sheath 30. The liquid-tight state can be confirmed by the phenomenon of the saline solution S overflowing from the proximal side of the introducer sheath 30.

[0040] 5D, the pusher wire 60 connected to the rear end of the stent 40 is operated from the proximal side (X1 side) to push the stent 40 toward the microcatheter 10. This allows the stent 40 housed in the introducer sheath 30 to be inserted into the through-hole 12 of the microcatheter 10.

[0041] According to the introducer sheath 30 of the first embodiment described above, flushing can be performed with the distal end 31 of the introducer sheath 30 abutted against the inner surface of the conical cylindrical channel 23 of the hub 21. During flushing, saline flows in through the gap g1 ( FIG. 3B ) formed between the liquid circulation portion 32 formed in the distal end 31 of the introducer sheath 30 and the inner surface of the conical cylindrical channel 23, allowing remaining air to be more reliably expelled without being affected by the liquid pressure of the saline. Furthermore, because the introducer sheath 30 of the first embodiment can be used in combination with a hub 21 having a general conical cylindrical channel 23, existing hub-equipped Y-connectors can be effectively utilized.

[0042] The liquid circulation portion 32 of the first embodiment can be formed by cutting off a portion of the distal end 31 of the introducer sheath 30 with a cutter or the like. This eliminates the need for dedicated equipment, allowing for more cost-effective manufacturing. Furthermore, because the liquid circulation portion 32 of the first embodiment has a simple inclined surface, it can be formed with a more accurate shape more easily and efficiently than when multiple small holes such as purge holes are formed. Furthermore, debris generated during processing is less likely to remain on the surface of the liquid circulation portion 32. Even if debris remains, it can be easily detected by visual inspection and removed. Thus, with the introducer sheath 30 of the first embodiment, debris generated during processing is less likely to remain on the surface of the liquid circulation portion 32, thereby preventing the gap g1 formed between the liquid circulation portion 32 and the inner surface of the conical-cylindrical flow path 23 from being blocked by debris.

[0043] The fluid circulation portion 32 of the first embodiment is provided on the distal end surface 33 of the introducer sheath 30 at a position that does not overlap with the opening 35 of the through-hole 34 (see FIG. 2A ). This prevents the stent 40 from expanding in diameter when pushed toward the microcatheter 10. The shape of the distal end portion 31 of the introducer sheath 30 is not limited to the conical shape shown in FIG. 2A and other figures. FIG. 6A is a perspective view showing another shape of the distal end portion 31 of the introducer sheath 30. FIG. 6B is a side view of FIG. 6A as viewed from the Y direction. In the introducer sheath 30 shown in FIGS. 6A and 6B , the distal end portion 31 is formed in a cylindrical shape with a constant outer diameter D from the rear end side (X1 side) to the distal end side (X2 side). The fluid circulation portion 32 is provided on the outer periphery of the cylindrical distal end portion 31. In the introducer sheath 30, even if the tip portion 31 is cylindrical, by providing a liquid circulation section 32 on the outer periphery of the tip portion 31, a gap can be formed between the tip portion 31 of the introducer sheath 30 and the inner surface of the conical-tubular flow path 23 when the tip portion 31 is abutted against the inner surface of the flow path of the hub 21.

[0044] The introducer sheath 30 may be translucent. For example, if the introducer sheath 30 is opaque, it is easy to check the abutment state with the hub 21, but it is difficult to check the state of the stent 40 housed therein. On the other hand, if the introducer sheath 30 is transparent, it is easy to check the state of the stent 40 housed therein, but it is difficult to check the abutment state with the hub 21. In contrast, if the introducer sheath 30 is translucent, not only is it easy to check the abutment state with the hub 21, but it is also easy to check the state of the stent 40 housed therein. To achieve this effect, the entire introducer sheath 30 may be translucent, or only the distal end side may be translucent. That is, the above effect can be achieved by making at least the distal end 31 of the introducer sheath 30 translucent. The introducer sheath 30 may be translucent in an uncolored state or in a colored state.

[0045] Second Embodiment Next, an embodiment of a hub according to the present invention will be described. The hub 121 of the second embodiment differs from the hub 21 of the first embodiment in that it includes a cylindrical flow path 123, which will be described later. The catheter stent system 1 of the second embodiment also differs from the first embodiment in that it uses a general introducer sheath 130 (see FIG. 4A ) that does not have a fluid circulation section 32 at its distal end 31. The other configurations are the same as those of the first embodiment. Therefore, in the drawings described below, the hub 121 is mainly illustrated, and the entire system is not illustrated. Furthermore, in the description and drawings of the second embodiment, components equivalent to those of the first embodiment are designated by the same reference numerals as those of the first embodiment, and redundant description will be omitted.

[0046] FIG. 7 is a perspective view showing the configuration of a hub 121 of the second embodiment. FIG. 8 is a schematic cross-sectional view of the hub 121 of the second embodiment. FIG. 9 is a cross-sectional view taken along line s3-s3 of FIG. 8. Note that FIG. 7 mainly illustrates the cylindrical flow path 123 of the hub 121, and other portions are omitted. As shown in FIG. 7, the hub 121 of the second embodiment includes a cylindrical flow path 123. The cylindrical flow path 123 has a quadrangular (non-circular) cross section perpendicular to the central axis direction X, and is formed into a quadrangular pyramid shape whose cross-sectional area gradually increases from the distal end (X2 side) to the proximal end (X1 side). Note that the quadrangular pyramid-shaped portion of the cylindrical flow path 123 (hereinafter also referred to as the "butting portion") may be formed only in the portion that abuts against the distal end 131 of the introducer sheath 130; the remaining portions may be conical. That is, the abutting portion may be formed over the entire cylindrical flow path 123, as shown in FIG. 7, or may be formed only in a portion thereof.

[0047] As shown in Fig. 8 , when the introducer sheath 130 is inserted into the cylindrical flow path 123 of the hub 121, the tip end 131 of the introducer sheath 130 abuts against the inner surface of the cylindrical flow path 123 at position Xc in the central axial direction X. In this state, as shown in Fig. 9 , gaps g3 are formed at four locations between the tip end 131 of the introducer sheath 130 and the inner surface of the cylindrical flow path 123. That is, gaps g3 are formed in each of the four corner regions where the tip end 131 of the introducer sheath 130 does not contact the inner surface of the cylindrical flow path 123. As such, with the hub 121 of this embodiment, even when the tip end 131 of the introducer sheath 130 abuts against the inner surface of the cylindrical flow path 123 of the hub 121, gaps g3 are formed at four locations between the periphery of the tip end 131 and the inner surface of the cylindrical flow path 123.

[0048] As described above, with the hub 121 of the second embodiment, flushing can be performed with the distal end 131 of the introducer sheath 130 abutted against the inner surface of the tubular flow path 123 of the hub 121. During flushing, saline flows through the gap g3 formed between the distal end 131 of the introducer sheath 130 and the inner surface of the tubular flow path 123. This allows remaining air to be more reliably expelled without being affected by the fluid pressure of the saline. Furthermore, the hub 121 of the second embodiment can be used in combination with a general introducer sheath 130 that does not have a fluid circulation section 32 formed in the distal end 131, thereby enabling effective use of existing introducer sheaths. While the second embodiment has been described with reference to an example in which the introducer sheath 130 has a conical distal end 131, the distal end 131 of the introducer sheath 130 may have a cylindrical shape with a constant outer diameter.

[0049] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and variations, such as those described below, are possible, and are also within the technical scope of the present invention. Furthermore, the effects described in the embodiments are merely a list of the most preferable effects resulting from the present invention, and are not limited to those described in the embodiments. Note that the above-described embodiments and the modifications described below can also be used in appropriate combinations, but detailed description thereof will be omitted.

[0050] (Modified Embodiment) Figures 10 to 15 are perspective views showing the shape of the distal end portion 31 of the introducer sheath 30 in a modified embodiment. In the figures described below, components equivalent to those of the first embodiment are designated by the same reference numerals as those of the first embodiment, and redundant description will be omitted. As shown in Figure 10, the fluid circulation portion 32 provided on the outer periphery of the distal end portion 31 of the introducer sheath 30 may have a concave cross section (groove) perpendicular to the central axis direction X. As shown in Figure 11, the fluid circulation portion 32 provided on the outer periphery of the distal end portion 31 of the introducer sheath 30 may have a substantially V-shaped cross section (groove) perpendicular to the central axis direction X. Although not shown, the fluid circulation portion 32 may also have a substantially U-shaped cross section (groove) perpendicular to the central axis direction X. As shown in Figure 12, two fluid circulation portions 32 may be provided on the outer periphery of the distal end portion 31 of the introducer sheath 30, spaced 180 degrees apart in a direction perpendicular to the central axis direction. Although Figure 12 shows an example in which two liquid circulation sections 32 are provided in the Z direction, the two liquid circulation sections 32 may be provided in any direction as long as they are perpendicular to the central axis direction X.

[0051] As shown in FIG. 13 , four fluid circulation sections 32 may be provided at 90-degree intervals on the outer periphery of the distal end 31 of the introducer sheath 30 in a direction perpendicular to the central axis direction X. In this embodiment, the distal end 31 of the introducer sheath 30 has a truncated pyramidal shape. While FIG. 13 shows an example in which four fluid circulation sections 32 are provided in the Y-Z direction, the four fluid circulation sections 32 may be provided in any direction as long as they are spaced apart at 90-degree intervals in a direction perpendicular to the central axis direction X. In addition to this embodiment, for example, three fluid circulation sections 32 may be provided at 120-degree intervals, or five or more fluid circulation sections 32 may be provided. Furthermore, when multiple fluid circulation sections 32 are provided, their shapes may differ from one another.

[0052] As shown in FIG. 14 , in a cylindrical introducer sheath 30, the fluid circulation portion 32 may be provided along the distal end (X2 side) to the proximal end (X1 side). The introducer sheath 30 shown in FIG. 14 is formed so that the outer diameter D is constant from the distal end, including the distal end portion 31, to the proximal end. In this embodiment, the proximal end side of the fluid circulation portion 32 may extend to the proximal end (not shown) of the introducer sheath 30, or may extend partway along the proximal end. As shown in FIG. 15 , in an introducer sheath 30 having a conical distal end portion 31, the fluid circulation portion 32 may be provided along the distal end side (X2 side) to the proximal end side (X1 side) of the distal end portion 31. Note that the proximal end side of the distal end portion 31 is not shown in FIG. 15 .

[0053] 16A and 16B are cross-sectional views showing the shape of the tubular flow channel 123 in a modified embodiment. FIGS. 16A and 16B are cross-sectional views corresponding to FIG. 9 . As shown in FIG. 16A , the cross section of the tubular flow channel 123 (hub 121) may be hexagonal. Even in a configuration in which the cross section of the tubular flow channel 123 is hexagonal, a gap g3 can be formed between the tubular flow channel 123 and the distal end 131 of the introducer sheath 130 against which it abuts. The cross section of the tubular flow channel 123 may be triangular, pentagonal, or more polygonal than a hexagon. Furthermore, as shown in FIG. 16B , the cross section of the tubular flow channel 123 (hub 121) may be elliptical. Even in a configuration in which the cross section of the tubular flow channel 123 is elliptical, a gap g4 can be formed between the tubular flow channel 123 and the distal end 131 of the introducer sheath 130 against which it abuts.

[0054] In the first embodiment, an example has been described in which the outer shape of the distal end surface 33 of the introducer sheath 30, at the position Xa where it abuts against the hub 21, is different from the shape of the cross section perpendicular to the central axis direction X of the conical-cylindrical channel 23 formed in the hub 21. However, this is not limiting. It is sufficient that the outer shape of the distal end surface 33 of the introducer sheath 30, at the position Xa where it abuts against the hub 21, is different from the shape of the cross section perpendicular to the central axis direction X of the cylindrical channel formed in the hub 21. Therefore, as long as the above requirements are met, for example, the introducer sheath 30 of the first embodiment may be combined with the hub 121 of the second embodiment.

[0055] In the first embodiment, an example has been described in which the distal end surface 33 of the distal end portion 31 of the introducer sheath 30 abuts against the hub 21, but this is not limiting. For example, if the distal end portion 31 of the introducer sheath 30 has a two-stage tapered shape tapering toward the distal end, and the distal end surface 33 of the distal tapered portion does not abut against the hub 21 but abuts against the hub 21 at the proximal tapered portion (the boundary between the two tapered portions), the cross-sectional outline of that portion may be non-circular. Specifically, the distal end portion 31 of the introducer sheath 30 may have a circular outer shape at the distal tapered portion, a non-circular outer shape at the cross-section of the proximal tapered portion, and the distal end portion 31 on the further proximal side may be circular. In this way, the distal end portion 31 of the introducer sheath 30 may include a portion whose cross-sectional shape perpendicular to the central axis direction X is non-circular, and this non-circular portion may be the distal end surface 33 or may be located proximal to the distal end surface 33.

[0056] In the above embodiment, the present invention has been described as being applied to a stent as an example of a medical device, but the present invention can also be applied to medical devices other than stents, such as coils for treating aneurysms, stents for redirecting blood flow, and placement devices to be placed in blood vessels, including stents for embolizing cerebral aneurysms.

[0057] REFERENCE SIGNS LIST 1 Catheter stent system 10 Microcatheter 20 Hubbed Y-connector 21, 121 Hub 23 Conical cylindrical flow path 30, 130 Introducer sheath 31, 131 Tip 32 Liquid flow path 40 Stent (medical device) 123 Cylindrical flow path

Claims

1. An introducer sheath used in inserting a medical instrument stored at the distal end into a microcatheter via a hub provided at the proximal end of the microcatheter, wherein the distal end of the introducer sheath includes a portion whose cross-sectional shape in a direction perpendicular to the central axis is non-circular.

2. An introducer sheath used in inserting a medical instrument stored at the distal end into a microcatheter via a hub provided at the proximal end of the microcatheter, wherein the outer shape of the distal end surface of the introducer sheath differs from the shape of a cross section perpendicular to the central axis of the cylindrical flow path at the position where the introducer sheath and a cylindrical flow path formed in the hub butt against each other.

3. An introducer sheath used in inserting a medical instrument stored at the tip side into a microcatheter via a hub provided at the base end of the microcatheter, the introducer sheath having a liquid circulation part on the outer periphery of the tip, the liquid circulation part having a shape that does not come into contact with the inner surface of a conical cylindrical flow path formed in the hub when the liquid circulation part is abutted against the conical cylindrical flow path, and has a shape that forms a gap that serves as a liquid circulation path between the liquid circulation part and the inner surface of the conical cylindrical flow path.

4. The introducer sheath according to claim 3, wherein the liquid circulation section is provided at a position on the end surface of the distal end of the introducer sheath that does not overlap with the opening hole.

5. The introducer sheath according to claim 3 or 4, wherein the liquid flow section is an inclined surface provided on the outer periphery of the distal end of the introducer sheath.

6. The introducer sheath according to claim 3 or 4, wherein the liquid circulation portion is a groove provided on the outer periphery of the distal end of the introducer sheath.

7. An introducer sheath according to any one of claims 1 to 6, wherein the distal end of the introducer sheath is conical in shape with an outer diameter that gradually decreases from the proximal end to the distal end.

8. The introducer sheath according to any one of claims 1 to 7, wherein the distal end of the introducer sheath is cylindrical.

9. The introducer sheath according to any one of claims 1 to 8, wherein at least the distal end of the introducer sheath is translucent.

10. A hub provided at the base end of a microcatheter, against which the tip of an introducer sheath containing a medical instrument is abutted during the process of inserting the medical instrument into the microcatheter, wherein at least a portion of a cylindrical flow path that communicates with the rear end of the microcatheter and against which the tip of the introducer sheath abuts is provided with an abutment portion that has a non-circular cross section perpendicular to the central axis and whose cross-sectional area gradually increases from the tip side to the rear end side.

11. The hub according to claim 10, wherein the cross section of the abutting portion perpendicular to the central axis is an n-sided polygon (n≧3).

12. A hub as set forth in claim 10, wherein a cross section of the abutting portion perpendicular to the central axis is elliptical.

13. A system comprising a medical instrument and an introducer sheath in which the medical instrument is stored at its distal end, wherein the outer shape of the distal end surface of the introducer sheath has a shape different from the shape of a cross section perpendicular to the central axis of a cylindrical flow channel formed in a hub provided at the proximal end of a microcatheter at the abutting position with the cylindrical flow channel, and the system is used to abut the distal end of the introducer sheath against the cylindrical flow channel of the hub, make the interior liquid-tight with liquid introduced through a gap formed between the distal end of the introducer sheath and the inner surface of the cylindrical flow channel, and then insert the medical instrument from the proximal end of the microcatheter.

14. The system according to claim 13, wherein, at the abutting position between the distal end of the introducer sheath and the cylindrical flow path of the hub, the length between the distal end surface of the introducer sheath and the proximal end of the microcatheter is greater than 0 mm and less than or equal to 10 mm.

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