JP2024011214A - clip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clip that can firmly hold a medical long device wound in a coil shape.

SOLUTION: A clip 10 for holding a flexible medical long device 100 wound in a coil shape comprises: a board 20 including a front surface 21, and a back surface 22; a holding part 30 including a cylindrical part 31 having a cylindrical shape comprising a lumen 35 penetrating in an axial direction Y parallel to the front surface 21, capable of being elastically deformed, and comprising a slit 39 extending between a first opening 37 and a second opening 38 opened on both sides in the axial direction Y, and a tooth part 33 formed on an outer surface of an upper opening end 40 forming the slit 39; and an engagement part 50 including a supporting part 51 extending from the front surface 21, and an opening operation part 53 supported by the supporting part 51 and comprising a claw part 52 in an end part opposed to the slit 39. The cylindrical part 31 comprises a compression member 36 to be compressively deformed by receiving a force on an inner surface to generate a restoring force.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a clip that holds an elongated medical device in a coiled manner.

In endovascular treatment, various long medical devices such as guide wires and catheters are used. During an endovascular treatment procedure, the operator may remove the guidewire outside the body and reinsert it into the blood vessel. The guidewire that has been removed from the body is coiled and temporarily stored in a liquid-filled container until it is reinserted.

The proximal end of the guidewire is made of a material with high rigidity and elasticity. This may cause the guidewire to attempt to return from its coiled state to its straight state, causing it to inadvertently pop out of the liquid-filled container and become contaminated. Therefore, means for holding the guide wire in a coiled state has been proposed.

US Pat. No. 5,001,002 discloses an apparatus for holding a flexible elongated device between contact surfaces provided on two jaws connected by a hinge operable by a handle and movable with respect to each other from a closed position to an open position. is disclosed.

US Patent Application Publication No. 2020/0289744

The device described above retains the elongate device by friction between the contact surface of the device and the outer surface of the elongate device when the device is in the closed position. However, if the surface of the elongated device is coated with a hydrophilic coating, the contact surface of the device and the surface of the elongated device may The retention force of the device on the elongated device is reduced. This allows the elongated device to move longitudinally or radially of the elongated device, slip between the contact surfaces of the device, return from a coiled state to a straight state, and eject from the container. There is sex.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a clip that can firmly hold a long medical device in a coiled state.

A clip according to the present invention that achieves the above object is a clip for holding a flexible long medical device in a coiled state, and the clip has a surface and a side opposite to the surface. between a first opening and a second opening that are elastically deformable and open at both ends in the axial direction; a cylindrical part provided with a third opening extending into the cylindrical part; a holding part including one tooth part; a support part extending from the surface; and an opening operation part supported by the support part and having at least one claw part at an end facing the third opening. The cylindrical portion has a compression member on its inner surface that is compressively deformed by receiving a force and generates a restoring force.

In the clip configured as described above, a loop of a long medical device wound in a coil is inserted into the inner cavity of the cylindrical portion of the clip in an open state through the third opening of the cylindrical portion, and then the cylindrical portion By elastically contracting the diameter of the clip and bringing the clip into a closed state by engaging the teeth of the holding part and the claws of the engaging part, the elongated device can be stably wound in a coiled state. Can be retained. A compression member provided on the inner surface of the cylindrical portion surrounds the entire loop of the elongated device and exerts a restoring force on the elongated device. This allows the clip to firmly hold the elongate device in a coiled state, even if the elongate device has a hydrophilic coating.

The clip may have an adhesive layer on the back surface of the substrate. This allows the clip to be secured to other objects such as long device storage containers, surgical drapes, and operating tables so that the long device held in a coiled state by the clip can be It can prevent it from falling from the table and becoming contaminated. Furthermore, the surgeon can open and close the clip with one hand.

The clip may have two side walls provided on the surface of the substrate and disposed at opposite ends of the upper open end in the axial direction. Thereby, the clip can suppress movement of the upper open end of the cylindrical portion in the axial direction, and therefore can stably hold the elongated device.

It is a front view showing a clip concerning an embodiment. It is a perspective view showing a clip concerning an embodiment. It is a front view showing the state where the slit of the clip concerning an embodiment is opened. FIG. 2 is a front view showing a state in which a long device is held in a clip according to an embodiment. FIG. 7 is a perspective view showing a modified example of the clip. FIG. 7 is a front view showing another modification of the clip.

Embodiments of the present invention will be described below with reference to the drawings. Note that the dimensional ratios in the drawings may be exaggerated and different from the actual ratios for convenience of explanation. Further, the expressions "upper", "lower", and "lateral" in this specification are used for convenience of explanation and do not limit the orientation of the clip.

As shown in FIG. 4, the clip 10 according to the present embodiment is used to hold a long medical device 100, such as a guide wire or a catheter, in a looped state in which it is wound multiple times and bundled.

As shown in FIGS. 1 and 2, the clip 10 includes a substrate 20, a holding portion 30 including a cylindrical portion 31 connected to the substrate 20, an engaging portion 50 connected to the substrate 20, and a substrate 20. and an adhesive layer 60 held therein. The loop of the long device 100 is held by engaging the holding portion 30 and the engaging portion 50 with the coiled loop of the long device 100 inserted into the inner cavity 35 of the holding portion 30. It is held in the lumen 35 of the section 30.

The substrate 20 has a flat plate shape and has a front surface 21 and a back surface 22 opposite to the front surface 21. In this embodiment, the front surface 21 side of the substrate 20 is defined as "upper", and the back surface 22 side is defined as "lower". In the present embodiment, a direction perpendicular to the front surface 21 and back surface 22 of the substrate 20 is referred to as an up-down direction Z, and a direction perpendicular to the up-down direction and perpendicular to the axis of a cylindrical portion 31, which will be described later, is referred to as a lateral direction X, and an up-down direction. The direction that is perpendicular to and parallel to the axis of the cylindrical portion 31 is defined as the axial direction Y. The axis of the cylindrical portion 31 is the direction in which the cylindrical through hole extends. The axial direction Y is perpendicular to the lateral direction X and the vertical direction Z. On the surface 21, the holding portion 30 and the engaging portion 50 are connected. An adhesive layer 60 is held on the back surface 22. The adhesive surface 61 of the adhesive layer 60 opposite to the surface in contact with the back surface 22 is protected by, for example, pasting a peelable release paper 62 until it is used for adhesion.

The adhesive layer 60 can fix the clip 10 to another object by adhering it to the other object.

The length of the substrate 20 in the lateral direction X is 12 mm to 50 mm. The length of the substrate 20 in the axial direction Y is 10 mm to 40 mm. The thickness of the substrate 20 in the vertical direction is 0.5 mm to 2 mm.

The substrate 20 is made of resin such as polypropylene, polyethylene, polystyrene, polyethylene terephthalate, polyamide, polycarbonate, vinyl chloride resin, or the like. The holding part 30 and the engaging part 50 can also be formed of a resin material that can be applied to the substrate 20, and may be integrally formed of the same material as the substrate 20.

Holder 30 is connected to surface 21 of substrate 20 . The holding part 30 has a cylindrical part 31, a closing operation part 32, and a tooth part 33.

The cylindrical portion 31 is an elastically deformable cylindrical member, and has a cylindrical wall 34 having an inner cavity 35 and a compression member 36 disposed on the inner surface of the wall 34 . The cylindrical portion 31 has an inner cavity 35 that passes through the cylindrical portion 31 from a first opening 37 at one end along the axial direction Y to a second opening 38 at the other end. In the cylindrical portion 31 , the axis of the inner cavity 35 is arranged parallel to the substrate 20 , and a part of the outer surface of the cylindrical portion 31 located at the lower part of the cylindrical portion 31 is connected to the surface 21 of the substrate 20 . The wall 34 of the cylindrical portion 31 has a slit 39 (third opening) extending from the first opening 37 to the second opening 38 along the axis. The slit 39 is provided so as to open in the lateral direction X of the cylindrical portion 31 . That is, the cross section of the cylindrical portion 31 perpendicular to the axial direction Y is approximately C-shaped. The cylindrical portion 31 has an upper open end 40 on the upper side with the slit 39 in between, and a lower open end 41 on the lower side. The cylindrical portion 31 is deformed so that the upper open end 40 and the lower open end 41 are separated from each other, thereby increasing the width of the slit 39 (see FIG. 3). Further, the cylindrical portion 31 is deformed so that the upper open end 40 and the lower open end 41 become closer to each other, so that the width of the slit 39 becomes narrower, or at least a portion of the upper open end 40 and the lower open end 41 They overlap, and the width of the slit 39 disappears (see FIG. 4). In this manner, the cylindrical portion 31 can take an open state in which the slit 39 is open and a closed state in which the slit 39 is closed by elastically deforming. In a natural state where no external force is applied, the cylindrical portion 31 is preferably in an open state, but may be in a closed state.

In a natural state where no external force is applied, the diameter of the inner cavity 35 of the cylindrical portion 31 in the open state with the slit 39 is 5 mm to 20 mm. The length of the cylindrical portion 31 in the axial direction Y is 5 mm to 20 mm. The wall thickness of the cylindrical portion 31 is 0.5 mm to 3 mm.

In a natural state where no external force is applied, the width of the slit 39 is preferably larger than the maximum outer diameter of the elongated device 100. The width of the slit 39 is 0.3 mm to 8 mm. Note that the width of the slit 39 only needs to be larger than the maximum outer diameter of the elongated device 100 when an external force is applied.

The closing operation part 32 is a member that the operator grasps and operates the cylindrical part 31 when reducing the diameter of the cylindrical part 31. The closing operation part 32 is provided at the upper part of the cylindrical part 31 (the part opposite to the lower part connected to the board 20) so as to protrude upward, that is, in a direction away from the board 20. The protrusion length of the closing operation part 32 from the outer surface of the cylindrical part 31 is 2.5 mm to 10 mm. The thickness of the closing operation part 32 is 0.5 mm to 2 mm. The closing operation portion 32 is formed at approximately the center of the cylindrical portion 31 in the axial direction Y. That is, the closing operation part 32 does not need to be provided on the side of the cylindrical part 31 that is closer to the first opening 37 and the side that is closer to the second opening 38. Note that the closing operation part 32 may be formed to extend from the first opening 37 to the second opening 38 of the cylindrical part 31.

One or more tooth portions 33 are provided on the outer surface of the upper open end 40 located above the slit 39 of the cylindrical portion 31 . In this embodiment, the number of teeth 33 is three, but it may be one, two, or four or more. The tooth portion 33 is combined with the claw portion 52 of the engagement portion 50 to form a ratchet mechanism, thereby maintaining the cylindrical portion 31 in a reduced diameter state. The tooth portion 33 is formed approximately at the center of the cylindrical portion 31 in the axial direction Y. That is, the tooth portion 33 does not need to be provided on the side of the cylindrical portion 31 closer to the first opening 37 and the side closer to the second opening 38. Note that the tooth portion 33 may be formed to extend from the first opening 37 to the second opening 38 of the cylindrical portion 31.

The compression member 36 is arranged on at least a portion of the inner surface of the cylindrical portion 31 . The compression member 36 is flexibly compressed and deformed by receiving a force, and generates a restoring force against compression. Note that it is preferable that the compression member 36 is not provided on the inner surface of the portion where the tooth portion 33 is provided on the outer surface of the cylindrical portion 31 . Thereby, when the cylindrical portion 31 is in the closed state, it is possible to prevent the compression member 36 from interfering with the engagement between the tooth portion 33 of the holding portion 30 and the claw portion 52 of the engaging portion 50. The compression member 36 is compressed and flexibly deformed when the cylindrical portion 31 is reduced in diameter. The compression member 36 is divided into a plurality of parts and arranged on the inner surface of the cylindrical part 31. Thereby, the diameter of the cylindrical portion 31 can be reduced without being hindered by the compression member 36. The compression member 36 is made of flexible resin such as urethane resin or silicone resin. The compression member 36 may be a porous material such as foam or sponge. Thereby, the compression member 36 can exert an appropriate restoring force on the elongated device 100 disposed in the inner cavity 35 of the cylindrical portion 31 . The restoring force of the compression member 36 allows the clip 10 to firmly hold the loop of the coiled elongate device 100 even if the elongate device 100 has a hydrophilic coating. Further, in the clip 10, the holding force of the elongated device 100 by the compression member 36 can be arbitrarily adjusted by appropriately selecting the tooth portion 33 that engages with the claw portion 52 of the engaging portion 50. Thereby, the clip 10 can hold various long devices having different specifications such as rigidity, elasticity, outer diameter, etc. in a coiled state. The thickness of the compression member 36 is 0.1 mm to 3 mm. It is preferable that the compression member 36 is provided from the first opening 37 to the second opening 38 on the inner surface of the cylindrical portion 31 .

The engaging portion 50 includes a support portion 51 extending upward from the surface 21 of the substrate 20, and an opening operation portion 53 supported by the support portion 51 and having a claw portion 52 on one side.

The support portion 51 is an elastically deformable plate-like member. The support portion 51 is provided on the surface 21 of the substrate 20 on the side having the upper open end 40 of the holding portion 30 in the lateral direction X, and extends upward while being inclined toward the holding portion 30 . The upper end of the support part 51 is arranged at approximately the same position as the slit 39 of the cylindrical part 31. The length of the support portion 51 in the axial direction Y is approximately the same as the length of the region of the holding portion 30 in which the teeth 33 are provided. An opening operation section 53 is provided at the upper end of the support section 51 . The thickness of the support portion 51 is preferably 0.5 mm to 2 mm.

The opening operation section 53 is a plate-shaped member arranged at the upper end of the support section 51. The opening operation part 53 is arranged to be substantially perpendicular to the support part 51, and has a claw part 52 extending in the axial direction Y formed on the side (end) of the cylindrical part 31 of the holding part 30 facing the slit 39. ing. The thickness of the opening operation part 53 is preferably 0.5 mm to 2 mm. The claw portion 52 is formed so that the thickness of the plate-like member decreases toward the slit 39 of the cylindrical portion 31. The claw portion 52 maintains the cylindrical portion 31 in a reduced diameter state by forming a ratchet mechanism in combination with the tooth portion 33 of the holding portion 30. Note that a plurality of claw portions 52 may be provided. When a plurality of claw portions 52 are provided, in addition to the claw portions 52 provided on the opening operation portion 53, the claw portions 52 extending in the axial direction Y are formed on the surface of the support portion 51 on the cylindrical portion 31 side.

Next, a method of using the clip 10 according to this embodiment will be explained.

During an endovascular treatment procedure, the operator may temporarily store the elongated device 100 (for example, a guide wire) that has been removed from the body in order to reinsert it into the blood vessel. At this time, the operator uses the clip 10 to hold the long device 100 that has been removed from the blood vessel in a coiled state. Note that the clip 10 can also be used to hold the proximal end of the elongated device 100 in a state where the distal end of the elongated device 100 is inserted into a patient's blood vessel in a coiled state.

First, the operator peels off the release paper 62 from the adhesive layer 60 of the clip 10 to expose the adhesive layer 60, and removes the adhesive layer 60 from a container (for example, a stainless steel vat) in which the elongated device 100 is stored, a surgical drape, or an operating table. The adhesive layer 60 is adhered to other objects such as. Thereby, the clip 10 is fixed to another object. As a result, the operator performs the opening/closing operation of the clip 10 (the operation of reducing the diameter of the cylindrical portion 31 of the holding portion 30 to hold the elongated device 100 in the clip 10, and the operation of the opening operation portion 53 of the engaging portion 50). The operation of releasing the elongated device 100 from the clip 10) can be easily performed with one hand. Further, it is possible to prevent the clip 10 from falling from the operating table and contaminating the elongated device 100. Note that the adhesive layer 60 may be attached to another object after the elongated device 100 wound in a coil around the clip 10 is held. Also, the adhesive layer 60 may not be used.

Next, the operator winds up the elongated device 100 that has been removed from the body into a coil. As a result, a plurality of loops are formed in the elongated device 100.

Next, as shown in FIG. 3, the operator grasps the closing operation part 32 of the clip 10 in the open state and applies force to separate the upper open end 40 of the cylindrical part 31 from the lower open end 41. , widening the width of the slit 39. Next, the operator inserts the plurality of loops of the elongated device 100 into the lumen 35 of the cylindrical portion 31 through the slit 39.

Next, as shown in FIG. 4, the operator presses the closing operation part 32 downward to reduce the diameter of the cylindrical part 31, and connects the upper open end 40 of the cylindrical part 31 to the claw part 52 of the engaging part 50. and the lower open end 41 of the cylindrical portion 31. As a result, the tooth portion 33 of the holding portion 30 engages with the claw portion 52 of the engaging portion 50, so that the compression member 36 provided on the inner surface of the cylindrical portion 31 surrounds the entire loop of the elongated device 100. Fixed to. At this time, the compression member 36 is flexibly compressed and deformed, and exerts a restoring force against the compression on the elongated device 100. Thereby, the clip 10 can firmly hold the elongated device 100 in a coiled state even if the elongated device 100 has a hydrophilic coating. Furthermore, in this embodiment, the clip 10 is provided with a plurality of teeth 33. Therefore, in the clip 10, the holding force of the elongated device 100 by the compression member 36 can be arbitrarily adjusted by appropriately selecting the tooth portion 33 that engages with the claw portion 52 of the engaging portion 50. Thereby, the clip 10 can hold various long devices having different specifications such as rigidity, elasticity, outer diameter, etc. in a coiled state. Note that when a plurality of claw portions 52 are provided, by appropriately selecting the claw portions 52 that engage with the tooth portions 33, the holding force of the elongated device 100 by the compression member 36 can be arbitrarily adjusted.

When removing the elongated device 100 from the clip 10, the operator grasps the opening operation section 53 of the engagement section 50 and presses it downward. As a result, the support portion 51 is bent, the claw portion 52 of the engagement portion 50 moves in a direction away from the cylindrical portion 31, and the engagement between the claw portion 52 and the tooth portion 33 is released. As a result, the cylindrical portion 31 is restored to its original shape by its own elastic force and becomes open. The operator can easily take out the loop of the elongated device 100 from the inner cavity 35 of the cylindrical portion 31 through the widened slit 39.

FIG. 5 shows a modification of this embodiment. The modified clip 10 includes two side walls 23 provided on the surface 21 of the substrate 20 to limit movement of the upper open end 40 of the cylindrical portion 31 in the axial direction Y, and two side walls 23 provided on the outer surface of the cylindrical portion 31 in the axial direction Y. It has at least one extending protrusion 70 .

The two side walls 23 are plate-shaped members that protrude upward from the surface 21 of the substrate 20. The two side walls 23 are arranged at positions opposite to both ends in the axial direction Y of the upper open end 40 inserted between the engaging portion 50 and the lower open end 41. Note that the configuration of the side wall 23 is not limited as long as it can restrict movement of the upper open end 40 of the cylindrical portion 31 in the axial direction Y. For example, the side wall 23 may be formed not on the substrate 20 but on the engaging portion 50 or the cylindrical portion 31.

When the operator inserts the upper open end 40 between the engaging part 50 and the lower open end 41 in order to close the cylindrical part 31, the upper open end 40 has two side walls at both ends in the axial direction Y. It is held in contact with 23. Note that the upper open end 40 may be arranged so as to have a small gap between both ends in the axial direction Y and the two side walls 23. Thereby, the movement of the upper open end 40, which is a free end, of the cylindrical portion 31 in the axial direction Y is restricted, and twisting of the upper open end 40 of the cylindrical portion 31 can be suppressed. As a result, the clip 10 can stably hold the elongated device 100. Further, in the clip 10, the cylindrical portion 31 is reinforced by the convex portion 70. This allows the operator to easily insert the upper open end 40 of the cylindrical portion 31 between the two side walls 23. Further, by providing the convex portion 70 on the outer surface of the cylindrical portion 31, the operator can grip the cylindrical portion 31 without slipping when using the clip 10.

Further, as in another modification shown in FIG. 6, the height and angle of the support part 51 of the engaging part 50, the position of the slit 39 of the cylindrical part 31, the position of the closing operation part 32, etc. may be changed as appropriate. . Further, the clip 10 may include a reinforcing wall 24 that connects the lower open end 41 of the cylindrical portion 31 and the surface 21 of the substrate 20. The reinforcing wall 24 can suppress bending and twisting of the lower open end 41 and improve the holding power of the clip 10 to the elongated device 100.

As described above, the clip 10 of aspect (1) according to the present embodiment is a clip 10 for holding a flexible medical long device 100 in a coiled state, and includes: It has a cylindrical shape including a substrate 20 including a front surface 21 and a back surface 22 opposite to the front surface 21, and a bore 35 penetrating in the axial direction Y parallel to the front surface 21, and is elastically deformable and extends in the axial direction Y. A cylindrical part 31 is provided with a slit 39 (third opening) extending between a first opening 37 and a second opening 38 that are open at both ends, and one of the two open ends facing each other so as to form the slit 39. a holding portion 30 including at least one tooth portion 33 formed on the outer surface of the upper open end 40 located away from the surface 21; a support portion 51 extending from the surface 21; The cylindrical part 31 has an inner surface that is compressively deformed by receiving a force. It has a compression member 36 that generates a restoring force. Thereby, the clip 10 of aspect (1) has a loop of the long medical device 100 wound in a coil form from the slit 39 of the cylindrical portion 31 into the inner cavity 35 of the cylindrical portion 31 of the clip 10 in the open state. After inserting the cylindrical portion 31, the diameter of the cylindrical portion 31 is elastically reduced, and the tooth portion 33 of the holding portion 30 and the claw portion 52 of the engaging portion 50 are engaged to bring the clip 10 into the closed state. The device 100 can be stably held in a coiled state. The compression member 36 provided on the inner surface of the cylindrical portion 31 surrounds the entire loop of the elongated device 100 and applies a restoring force to the elongated device 100. Thereby, the clip 10 can firmly hold the elongated device 100 in a coiled state even if the elongated device 100 has a hydrophilic coating. In addition, since the clip 10 is provided with a plurality of teeth 33, the long device 100 can be held by the compression member 36 by appropriately selecting the teeth 33 that engage with the claws 52 of the engagement portion 50. The force can be adjusted arbitrarily. Therefore, the clip 10 can hold various long devices having different specifications such as rigidity, elasticity, outer diameter, etc. in a coiled state.

The clip 10 of aspect (2) has an adhesive layer 60 on the back surface 22 of the substrate 20 in the clip 10 of aspect (1). As a result, the clip 10 can be fixed to other objects such as a container for storing the elongated device 100, a surgical drape, and an operating table, so that the elongated device 100 held by the clip 10 does not fall off the operating table. This can prevent contamination. Further, the operator can open and close the clip 10 with one hand.

The clip 10 of aspect (3) is the clip 10 of aspect (1) or (2), which is provided on the surface 21 of the substrate 20 and arranged at positions facing both ends of the upper open end 40 in the axial direction Y. It may have two side walls 23. Thereby, the clip 10 can restrict movement of the upper open end 40 of the cylindrical portion 31 in the axial direction Y, and therefore can stably hold the elongated device 100.

Note that the present invention is not limited to the embodiments described above, and various modifications can be made by those skilled in the art within the technical idea of the present invention. For example, in the embodiments described above, the medical long device 100 is a guide wire, but it may be another long device 100 such as a catheter.

10 clip 20 substrate 21 front surface 22 back surface 23 side wall 24 reinforcing wall 30 holding section 31 cylindrical section 32 closing operation section 33 tooth section 34 wall 35 inner cavity 36 compression member 37 first opening 38 second opening 39 slit (third opening)
40 Upper open end 41 Lower open end 50 Engagement part 51 Support part 52 Claw part 53 Opening operation part 60 Adhesive layer 61 Adhesive surface 62 Release paper 70 Convex part 100 Long device X Lateral direction Y Axial direction Z Vertical direction

Claims (3)

A clip for holding a flexible long medical device in a coiled state,
a substrate including a front surface and a back surface opposite to the front surface;
A cylinder having a cylindrical shape with an inner cavity penetrating in an axial direction parallel to the surface, and having a third opening extending between a first opening and a second opening that are elastically deformable and open at both ends in the axial direction. and at least one tooth formed on the outer surface of the upper open end located on the side remote from the surface of the two opposing open ends so as to form the third opening. Department and
an engaging portion including a support portion extending from the surface; and an opening operation portion supported by the support portion and having at least one claw portion at an end facing the third opening;
The cylindrical portion has a compression member on its inner surface that is compressively deformed by receiving a force and generates a restoring force. The clip according to claim 1, wherein the clip has an adhesive layer on the back surface of the substrate. The clip according to claim 1 or 2, wherein the clip has two side walls provided on the surface of the substrate and arranged at positions opposite to both ends of the upper open end in the axial direction.

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