Catheter

Abstract

Provided is a catheter having a novel structure capable of improving characteristics that have been difficult to achieve conventionally, namely, at least one of an improvement in pushability and an improvement in positioning accuracy in a circumferential direction, etc.　A catheter 10 includes: a first lumen 20 having a braid 62 surrounding the outer periphery of the lumen; a second lumen 22 having no braid surrounding the outer periphery of the lumen; and an outermost peripheral braid 74 disposed on the outer periphery of a catheter body 12 having the first lumen 20 and the second lumen 22.

Description

Catheter

[0001] The present invention relates to a catheter having a first lumen and a second lumen extending in the longitudinal direction and being inserted into a blood vessel or the like for use.

[0002] Conventionally, a catheter that is inserted into a lumen such as a blood vessel for use in treating animals including humans has been known. The catheter is provided with a lumen, and through such a lumen, a guide wire can be inserted, a fluid for expansion and contraction can be supplied and discharged to a balloon provided on the distal end side, a fluid such as physiological saline can be supplied and discharged into the body, and a treatment device can be inserted and removed, etc.

[0003] By the way, various characteristics are required for a catheter according to the treatment target site, application, etc., such as good flexibility, pushability, pull-out strength, etc. for reaching the target site in the lumen at the distal end. Specifically, for example, as described in Patent Document 1 (WO2013 / 080729), in an atherectomy catheter that cuts and collects atherosclerotic plaque with a cutter through a window portion that opens laterally on the distal end side, in addition to ensuring flexibility while preventing the lumen from collapsing, accurate circumferential positioning characteristics and circumferential torque transmission characteristics, etc. for adjusting the opening direction of the window portion are required.

[0004] Therefore, in conventional catheters, improvement of operating characteristics has been attempted by arranging blades around the lumen or embedding reinforcing members. However, it has been difficult to obtain sufficient characteristics, especially in catheters having a plurality of lumens.

[0005] In other words, a catheter with multiple lumens can be manufactured, for example, as described in Patent Document 2 (Japanese Patent Application Publication No. 2022-175116), by overlapping multiple tubes that form each lumen and then externally inserting an outer tube and welding the whole together. Here, it is conceivable to embed a rod-shaped reinforcing member that extends parallel to the outside of the lumen, as described in Patent Document 1, but although the pull-out strength is increased by the reinforcing member, it was difficult to obtain sufficient improvement in circumferential (torsional) properties. It is also conceivable to use a double-braided tube having a double braided layer as the tube that forms each lumen, but not only is it difficult to keep the overall outer diameter of the catheter small because each tube becomes thicker, but it was still difficult to obtain sufficient circumferential (torsional) rigidity or operability of the catheter as a whole.

[0006] Japanese Patent Publication No. WO2013 / 080729, No. 2022-175116

[0007] The present invention aims to provide a catheter with a novel structure that can improve at least one of the properties that were previously difficult to achieve, such as improved pushability and improved positioning accuracy in the circumferential direction, for use by inserting it into a lumen in the body, such as a blood vessel.

[0008] The following describes several aspects of the present invention, which was made to solve these problems. The components used in each of the following aspects can be used in any combination as much as possible. Furthermore, the aspects or technical features of the present invention are not limited to those described below, but should be understood based on the inventive concept described in the entire specification and drawings, or as can be grasped by those skilled in the art from such descriptions.

[0009] A first aspect of the present invention relates to a catheter having a plurality of lumens, as follows: a catheter comprising: a first lumen having a blade surrounding its outer circumference; a second lumen not having a blade surrounding its outer circumference; and an outermost blade disposed on the outer circumference of a catheter body having the first lumen and the second lumen.

[0010] In this embodiment, the presence of an outermost blade surrounding the outer circumference of the catheter body, including the first and second lumens, improves torque transmission characteristics. Furthermore, the absence of blade reinforcement in the second lumen prevents the catheter from becoming larger, making it easier to reduce its diameter. In particular, the improved torque transmission characteristics allow the operator to precisely change the circumferential orientation of the distal end within the lumen by, for example, rotating the catheter at the proximal end. In addition, the combined structure of the blade surrounding the first lumen and the outermost blade stabilizes the cross-sectional shape of not only the first lumen but also the second lumen, effectively preventing lumen collapse.

[0011] A second aspect of the present invention is a catheter according to the first aspect, wherein the peripheral wall of the first lumen is formed by a first tube, and the main body layer forming the second lumen covers the outer circumference of the first tube and is integrated with it.

[0012] In this embodiment of the catheter, the second lumen is formed by the main body layer itself rather than a tube, allowing the peripheral wall portion of the second lumen to be integrally formed with a large cross-sectional area consisting of a single, integrated resin structure extending to the outer circumference of the catheter. As a result, the strength of the peripheral wall portion of the second lumen, which is not reinforced with a blade, is improved, and collapse of the second lumen can be prevented more effectively.

[0013] A third aspect of the present invention is a catheter according to the second aspect, wherein the main body layer comprises an inner circumferential middle layer that covers the outer circumference of the first tube and forms the second lumen, and an outer layer that surrounds the outer circumference of the middle layer and on which the outermost blade is arranged.

[0014] In this embodiment, the catheter has a double-layer structure consisting of a middle layer containing a first lumen and a second lumen, and an outer layer covering the outer circumference of the middle layer. This makes it easy to implement an embedded structure for the outermost blade, and also allows for improved flexibility in tuning characteristics by setting the middle layer inside the catheter and the outer layer on the catheter surface to be made of different materials. Furthermore, by using a middle layer of a single material along the entire length of the catheter, while varying the material of the outer layer in different parts along the length of the catheter, it becomes easy to adjust the bending deformation characteristics of the catheter in different parts along the length, thereby adjusting pushability and rotational torque transmission.

[0015] A fourth aspect of the present invention is a catheter according to any of the first to third aspects, wherein the blade surrounding the outer circumference of the first lumen has a single-blade structure, while the outermost blade has a double-blade structure.

[0016] In this embodiment of the catheter, by using a single blade surrounding the first lumen, the thickness of the peripheral wall portion of the first lumen and the boundary wall portion between the first and second lumens can be reduced, while surrounding the entire outer circumference of the catheter with a double blade efficiently prevents lumen collapse and improves the torque transmission characteristics of the catheter.

[0017] A fifth aspect of the present invention is a catheter according to any of the first to fourth aspects, wherein the cross-sectional area of ​​the first lumen is larger than the cross-sectional area of ​​the second lumen.

[0018] In this embodiment of the catheter, reinforcing the peripheral wall portion of the first lumen, which has a larger cross-sectional area, with a blade makes it possible to more efficiently improve the overall strength characteristics of the catheter and prevent deformation and collapse of each lumen.

[0019] A sixth aspect of the present invention is a catheter according to any of the first to fifth aspects, wherein a non-braided region is provided at the distal end in the longitudinal direction, where the outermost braid is not located.

[0020] In this embodiment of the catheter, the distal end can be bent more easily by providing a region where the outermost blade is not present. Therefore, for example, when inserting the distal end through a curve or branch with a large curvature to reach a target site such as a blood vessel, further improvements in operability can be achieved. It is desirable to provide a blade surrounding the outer circumference of the first lumen even in the non-braided region, as this makes it easier to achieve required characteristics such as kink resistance.

[0021] A seventh aspect of the present invention is a catheter according to any of the first to sixth aspects, wherein a balloon is provided on the distal end of the catheter body, and the balloon lumen for supplying and discharging an expansion and contraction fluid to the balloon is configured by the second lumen.

[0022] In this embodiment of the catheter, the peripheral wall portion of the second lumen can be made strong enough to withstand the pressure of supplying and discharging the fluid used to expand and contract the balloon, thanks to the strength of the peripheral wall itself and the presence of the outermost blade.

[0023] An eighth aspect of the present invention is a catheter according to any of the first to seventh aspects, wherein a cutter is provided on the distal end side of the catheter body, and the shaft lumen through which a shaft that applies rotational driving force to the cutter is inserted is formed by the first lumen.

[0024] In this catheter embodiment, the blade surrounding the first lumen and the blade arranged on the outer circumference of the catheter body prevent torsional deformation caused by the rotational torque and sliding resistance of the shaft inserted into the first lumen and rotating, thereby achieving stable rotational operation of the cutter. Furthermore, since the amount of deformation of the first lumen is kept to a minimum, rotational resistance due to contact with the shaft is also reduced, making it possible to rotate the cutter efficiently.

[0025] A ninth aspect of the present invention relates to a catheter equipped with a rotary cutter, as follows: A catheter in which a cutter is disposed in a cylindrical housing at the distal end of the catheter body, and the cutter rotates and moves to cut atheroma that has entered the cylindrical housing through a window and send it into the nose cone at the front, wherein a guide wire support is disposed on the inlet side of the nose cone to support a guide wire inserted through the cutter, the guide wire support has a guide wire insertion hole that penetrates the central part in the axial direction, and a communication hole that is provided on the outer circumference of the guide wire insertion hole, which spreads in an arc shape in the circumferential direction and penetrates in the axial direction, for sending the atheroma cut by the cutter into the nose cone, the catheter in which the communication hole has curved shapes at both ends in the circumferential direction that spread out more than half the circumference around the wire insertion hole, and reaches a circumferential position where it wraps around the wire insertion hole from both sides in the circumferential direction and approaches each other.

[0026] In this embodiment of the catheter, the guide wire inserted into the cutter is supported by a guide wire support located at the tip of the window portion. As a result, the center of rotation is maintained by the guide wire, allowing the cutter to rotate and feed stably. Furthermore, a communication hole located on the path through which the atheroma cut by the cutter is fed from the cylindrical housing into the nose cone is formed in the guide wire support with sufficient circumferential size.

[0027] Therefore, while ensuring sufficient support for the guidewire by such a guidewire support, and consequently stabilizing the rotational operation of the cutter, it becomes possible to smoothly guide and contain the cut atherosclerotic plaque within the nose cone. This can lead to improved stability and efficiency in the procedure of cutting and removing atherosclerotic plaque.

[0028] A tenth aspect of the present invention is a catheter according to the ninth aspect, wherein the guidewire support comprises an outer cylindrical portion connected to the nose cone, an inner cylindrical portion constituting the circumferential wall of the guidewire insertion hole, and a connecting portion located between the circumferential ends of the communication hole and connecting the outer cylindrical portion and the inner cylindrical portion, wherein the proximal end surface of the connecting portion is formed on the proximal end side, gradually inclined toward the tip towards the circumferential ends of the communication hole.

[0029] In this embodiment of the catheter, the communication hole is formed in the circumferential portion excluding the connecting portion, extending circumferentially between the radial distance between the inner circumferential cylinder portion and the outer circumferential cylinder portion. When the atheroma cut by the cutter is sent from inside the cylindrical housing to the communication hole, it may be pressed against the connecting portion, or it may be pressed against the connecting portion while rotating as the cutter rotates. In this embodiment, the circumferentially inclined surface provided on the proximal end surface of the connecting portion guides the pressed atheroma smoothly into the communication hole and then into the nose cone. As a result, the risk of the atheroma being broken into small pieces and leaking out through the window portion, etc., is reduced, and the cut atheroma can be smoothly and efficiently accommodated into the nose cone.

[0030] An eleventh aspect of the present invention is a catheter according to the ninth or tenth aspect, wherein the guidewire support has an axially inclined surface formed on the proximal end surface between the circumferential ends of the circumferential portions of the communication hole, which extends smoothly toward the axial proximal end without any steps from the guidewire insertion hole toward the radially outward direction.

[0031] In the catheter of this embodiment, the proximal end surface of the circumferential connection hole (the connecting portion in the ninth embodiment) is an axially inclined surface that extends smoothly in the axial direction. Therefore, even if a plaque cut by a cutter is pressed against this axially inclined surface when it is sent from the cylindrical housing to the connection hole, it will be smoothly guided toward the tip. Consequently, the pressing force acting on the plaque is reduced, making it possible to smoothly guide the cut plaque from the connection hole into the nose cone, and also reducing the risk of the plaque being broken into pieces and leaking out through the window or other openings.

[0032] A twelfth aspect of the present invention is a catheter according to any of the ninth to eleventh aspects, wherein the guidewire support is made of metal.

[0033] In this embodiment of the catheter, by using a metal guidewire support to ensure structural strength, further miniaturization becomes possible, and for example, the dimensions of the circumferential distance between the communication holes (the connecting portion in the ninth embodiment) can be made smaller. As a result, the effective passage cross-sectional area of ​​the communication holes can be increased, making it possible to pass the atherosclerotic ulcer, which has been cut by the cutter, more smoothly.

[0034] A thirteenth aspect of the present invention is a catheter according to any nine to twelfth aspects, wherein the guidewire support has support holes formed in the circumferential direction between the circumferential ends of the communication hole, opening toward the tip side, and a reinforcing member is provided that protrudes toward the tip side from the support holes.

[0035] In this embodiment of the catheter, the nose cone provided on the atoso side can be reinforced by a reinforcing member supported by a guidewire support made of a rigid material. Therefore, it becomes possible to make the nose cone itself sufficiently soft to prevent damage to blood vessels, etc., or to make it thin to secure a large amount of atherosclerotic plaque that can be accommodated. Moreover, it is possible to set different materials and properties for the guidewire support and the reinforcing member, thereby improving the properties required for each member.

[0036] According to the present invention, a catheter with a novel structure is provided that achieves improved properties that were previously difficult to realize.

[0037] For example, according to the catheter of the first aspect of the present invention, it is possible to reduce the overall diameter of the catheter while simultaneously preventing collapse of the first and second lumens and improving torque transmission characteristics.

[0038] Furthermore, according to the catheter according to the ninth aspect of the present invention, for example, it becomes possible to smoothly deliver and accommodate the cut atherosclerotic plaque into the nose cone while ensuring the stability of the rotational and feeding operations of the cutter that cuts the plaque.

[0039] Figure 1 shows an overall schematic diagram of a catheter for atherosclerosis removal as one embodiment of the present invention. Figure 1 shows an enlarged explanatory diagram of the distal end of the catheter shown in Figure 1. Figure 1 shows a cross-sectional view of the catheter body, which corresponds to the III-III section in Figure 1. Figure 1 shows a cross-sectional view of the catheter body, which corresponds to the IV-IV section in Figure 1. Figure 5 shows an enlarged plan view of the atherosclerosis removal portion of the catheter shown in Figure 1. Figure 5 shows the VI-VI section. Figure 6 shows an enlarged explanatory diagram of part a. Figure 6 shows an enlarged explanatory diagram of part b. Figure 6 shows an enlarged cross-sectional view corresponding to the IX-IX section in Figure 6. Figure 6 shows an enlarged cross-sectional view corresponding to the X-X section in Figure 6.

[0040] Embodiments of the present invention will be described below with reference to the drawings.

[0041] First, Figure 1 shows a schematic diagram of the overall lateral appearance of a catheter 10 for excising atherosclerotic plaque as a first embodiment of the present invention, and Figure 2 shows an enlarged view of the distal end of the catheter 10.

[0042] The catheter 10 of this embodiment comprises (1) a catheter body 12 which is an outer shaft, (2) a plaque treatment portion 14 provided on the distal end side of the catheter body 12, and (3) a connector portion 16 provided on the proximal end side of the catheter body 12, as described in the following section [I] Basic Structure.

[0043] [I] Basic Structure (1) [Catheter Body 12] As will be described in detail later, the catheter body 12 has a double lumen structure in which a first lumen 20 and a second lumen 22 are formed over the entire length as shown in FIGS. 3 and 4. In the present embodiment, the first lumen 20 having a large cross-sectional area is the main lumen, and the second lumen 22 having a small cross-sectional area is the balloon lumen for supplying and discharging fluid to and from the balloon.

[0044] (2) [Atherosclerotic Lesion Treatment Portion 14] As shown in FIG. 2, the atherosclerotic lesion treatment portion 14 has a hollow cutter housing 26 connected to the distal end side of the catheter body 12, and a nose cone 28 extending in a cylindrical shape is connected to the distal end side of the cutter housing 26. Further, a tip chip 30 that tapers in diameter and extends to the distal end side with a smaller diameter cylindrical shape is provided at the tip of the nose cone 28.

[0045] The cutter housing 26 houses a rotary cutter 32 so as to be rotatable about the central axis and movable in the central axis direction as shown in FIGS. 5 and 6. Such a cutter 32 is attached to the distal end of a shaft 34 as a drive shaft inserted into the first lumen 20 of the catheter body 12. Then, by the driving force exerted from the outside through the shaft 34, the cutter 32 is rotated and axially moved within the cutter housing 26.

[0046] Further, a window portion 36 penetrating the peripheral wall inside and outside is formed in the cutter housing 26. The window portion 36 extends at a predetermined length in the central portion in the axial direction with a predetermined width in the circumferential direction (in the present embodiment, the circumferential width extending over substantially half a circumference).

[0047] As a result, the cutter 32 moving axially within the cutter housing 26 is exposed in a state where it can be seen from the outside through the window portion 36. Then, the atherosclerotic lesion that has entered the cutter housing 26 from the window portion 36 is cut by the rotation and movement of the cutter 32, and the excised atherosclerotic lesion is sent forward together with the axial movement of the cutter 32, so that it becomes a thin-walled soft structure and is accommodated inside the nose cone 28 that secures an accommodation area.

[0048] Further, the atherosclerotic lesion treatment portion 14 includes a balloon 40 disposed on the outer peripheral surface of the cutter housing 26. This balloon 40 is provided on the radially opposite side to the window portion 36 of the cutter housing 26. Such a balloon 40 is configured to be expanded / contracted by supplying and discharging the operating fluid through the second lumen 22 of the catheter body 12.

[0049] And at the treatment target site within the blood vessel, the balloon 40 is expanded with the window portion 36 facing the atherosclerotic lesion, and the window portion 36 of the cutter housing 26 is pressed against the atherosclerotic lesion by the contact reaction force of the balloon 40 against the inner surface of the blood vessel, so that the atherosclerotic lesion enters from the window portion 36 into the cutter housing 26. In FIG. 6, the balloon 40 is shown in a slightly inflated state, but when inserting / removing into / from the blood vessel, since the contracted balloon 40 is adhered to the surface of the cutter housing 26, in other figures, the balloon 40 is shown in a simplified representation with reduction.

[0050] (3) [Connector portion 16] The connector portion 16 is a portion that is left outside the body in a state where the atherosclerotic lesion treatment portion 14 is inserted into the body during the treatment and is gripped and operated by the operator. The elongated main body housing 44 connected to the proximal end of the catheter body 12 is provided with a flush port 46 and a balloon port 48 having a branch port structure, which are respectively communicated with the first lumen 20 and the second lumen 22 of the catheter body 12.

[0051] Thereby, for example, by using a syringe or the like connected to the flush port 46, the first lumen 20 can be appropriately flushed with heparin - added physiological saline or the like. Also, by using an inflation device, a syringe or the like connected to the balloon port 48, physiological saline, contrast agent or the like is supplied and discharged to the balloon 40 so that the balloon can be expanded / contracted.

[0052] Furthermore, a shaft 34, which is inserted into the first lumen 20 of the catheter body 12, passes through the main body housing 44 in the longitudinal direction and protrudes from the proximal end of the main body housing 44. In addition, the proximal end of the protruding shaft 34 is an MDU connection part 50, to which a motor drive unit equipped with a battery, motor and control switch is connected.

[0053] The MDU connection section 50 is connected to the output shaft of the motor drive unit so as to be axially movable relative to it. A knob-shaped advance / retract controller 52 is provided protruding outward from the tip of the MDU connection section 50. By pushing or pulling this advance / retract controller 52, the operator can move the shaft 34 axially within the first lumen 20 of the catheter body 12, thereby moving the aforementioned cutter 32 attached to the distal end of the shaft 34 forward or backward within the cutter housing 26.

[0054] In other words, the operator can control the rotational and forward / backward movement (axial movement) of the cutter 32 by operating a switch on the motor drive unit connected to the MDU connection part 50 and by operating the forward / backward controller 52. In this embodiment, the forward / backward controller 52 can be pressed and moved in the circumferential direction to lock the axial position of the shaft 34 and, consequently, the cutter 32 within the cutter housing.

[0055] Furthermore, a guide wire lumen is provided through the shaft 34 in the longitudinal direction. That is, the shaft 34 has a hollow structure, and the guide wire can be inserted into and removed from the shaft 34 through the opening of the guide wire lumen formed at the base end of the MDU connection part 50. As shown in Figures 5 and 6, the guide wire 56 inserted into the shaft 34 passes through the cutter 32 at the distal end, and extends towards the tip side through the nose cone 28 and the tip 30.

[0056] (II) Basic Usage The catheter 10 for atherosclerotic plaque removal of this embodiment, having the basic structure described above, can be used in the same way as the catheter described in Patent Document 1 (WO2013 / 080729).

[0057] Specifically, preparatory procedures are performed, such as flushing the first lumen 20 and deflating the balloon 40 by inflation and negative pressure deflation, while the target lesion containing the atherosclerotic plaque to be resected is confirmed according to the procedure of normal coronary interventional therapy. Then, the catheter 10, with the guidewire 56 inserted into the first lumen 20, is inserted into the ascending aorta under X-ray fluoroscopy through a guiding catheter that has been previously inserted into the blood vessel. Furthermore, near the vascular inlet, the guidewire 56 is extended forward from the tip 30, passed through the target lesion, and inserted into the main blood vessel.

[0058] Next, the catheter 10 is advanced along the guide wire 56, and torque is applied to the catheter 10 from the connector portion 16 or the motor drive unit to adjust the circumferential position of the window portion 36 of the cutter housing 26, thereby positioning the window portion 36 toward the atherosclerosis to be excised. Furthermore, the balloon 40 is expanded and the reaction force against the inner surface of the blood vessel is used to press the window portion 36 of the cutter housing 26 against the atherosclerosis to be excised, causing the atherosclerosis to enter the cutter housing 26 through the window portion 36.

[0059] Subsequently, the motor drive unit and the forward / backward controller 52 are activated and operated to apply rotational driving force and forward movement force to the cutter 32, which is waiting in the retracted position within the cutter housing 26, via the shaft 34. This cuts the plaque that has entered through the window 36 of the cutter housing 26, and pushes the excised plaque (excised plaque) forward into the nose cone 28. The plaque can be excised by repeatedly moving the cutter 32 forward and backward multiple times. Furthermore, when repeatedly excising the plaque by moving the cutter 32 forward and backward multiple times, the balloon 40 can be temporarily deflated to appropriately change the opening direction of the window 36 of the cutter housing 26 in the circumferential direction before performing the excision with the cutter 32 again.

[0060] When the excised atherosclerotic plaque has almost completely filled the nose cone 28, the advance / retract controller 52 is used to fix the cutter 32 at the forward end, and the balloon 40 is deflated to remove the catheter 10 from the body. The removed catheter 10 can be reinserted into the blood vessel and used to excise any remaining atherosclerotic plaque after being flushed with saline solution in a sterile environment to remove the excised atherosclerotic plaque accumulated in the nose cone 28, and after further inspection.

[0061] (III) Detailed Structure The catheter 10 for atherosclerotic cyst removal of this embodiment, having the basic structure described above, has the following specific configurations, particularly in (1) the catheter body 12 and (2) the atherosclerotic cyst treatment portion 14 (tip portion).

[0062] (1) Catheter body 12 The catheter body 12 has a double lumen structure formed along its entire length, with a first lumen 20 through which the drive shaft 34 and guide wire 56 are inserted, and a second lumen 22 as a balloon lumen for supplying and discharging fluid to and from the balloon 40. The length of the catheter body 12 can be appropriate depending on the treatment site, but for example it is formed with a total length of 1000 to 2000 mm.

[0063] Figure 3 shows the basic structure of the catheter body 12, which occupies most of the length region.

[0064] In other words, the peripheral wall portion of the first lumen 20 is composed of a first tube 60 made of a tubular structure. Furthermore, the first lumen 20 has an inner blade 62 that surrounds its outer circumference.

[0065] The first tube 60 can be obtained by general tube molding processes such as extrusion molding, and its material is not limited; various resin materials can be used depending on the required characteristics. Specifically, for example, a fluororesin such as low-friction PTFE can be used as the resin material for the first tube 60. The first tube 60 can be made sufficiently thin; for example, when formed from PTFE, it can be 0.1 mm or less, and more preferably 0.05 mm or less in thickness. The inner braid 62 is not limited in material or specific structure, and uses a reinforcing material made of wire such as metal, tungsten, or resin, which has a higher tensile strength than the first tube 60. Depending on the required characteristics, various structures such as braiding into a cylindrical shape or winding into a coil shape can be used. In this embodiment, the inner braid 62 is constructed as a single braid structure consisting of a single braid layer made by braiding metal wire such as stainless steel. Furthermore, the inner circumferential protective layer 64 is adopted as needed, and its presence or absence and material are not limited; for example, a fluororesin layer such as low-friction PTFE may be adopted depending on the required characteristics.

[0066] On the other hand, the peripheral wall portion of the second lumen 22 is composed of a main body layer 66. This main body layer 66 has an intermediate layer 68 that surrounds the entire outer circumference of the first tube 60, and the first lumen 20 and the second lumen 22 are located inside this intermediate layer 68. The inner blade 62 surrounding the outer circumference of the first tube 60 is embedded in the intermediate layer 68. Furthermore, the intermediate layer 68 that constitutes the peripheral wall portion of the second lumen 22 does not have a blade, and the second lumen 22 has a lumen structure without a blade.

[0067] Furthermore, the material of the middle layer 68 is not limited, and various resin materials can be used depending on the required characteristics. For example, polyamide resins such as Pebax can be used. In addition, an inner circumferential protective layer 70 made of a low-friction PTFE fluororesin or the like can be formed on the inner circumferential surface of the second lumen 22 as needed. Such an inner circumferential protective layer can be made sufficiently thin, and can even be made thinner than the first tube 60, for example.

[0068] The intermediate layer 68 can be formed, for example, by externally inserting the inner blade 62 onto a pre-formed first tube 60, and then forming a predetermined resin material on its outer surface by extrusion molding or the like. The intermediate layer 68 formed in this way constitutes the peripheral wall of the second lumen 22, and also constitutes the outer wall of the first tube 60 or the outer layer of the first lumen 20 with the structure in which the inner blade 62 is embedded. In addition, the intermediate layer 68 may be fused together with the outer surface of the first tube 60 in a molten state.

[0069] Furthermore, the main body layer 66 has a cylindrical outer layer 72 that covers the entire cylindrical outer surface of the middle layer 68. The outermost outermost blade 74, which acts as a braid surrounding the outer circumference of the middle layer 68, is embedded in this outer layer 72. The outermost outermost blade 74, like the inner blade 62 mentioned above, is not limited in material or specific structure, and is made of a reinforcing material with greater tensile strength than the main body layer 66, such as a wire made of metal, tungsten, or resin, and can have various structures depending on the required characteristics, such as being braided into a cylinder or wound into a coil.

[0070] In this embodiment, the inner blade 62 arranged on the outer peripheral wall of the first lumen 20 has a single-blade structure, whereas the outermost blade 74 arranged on the outer peripheral wall of the main body layer 66 has a double-blade structure, which is formed by overlapping two sleeve-shaped blade layers made of braided metal wires such as stainless steel in an in-and-out-of-the-radial state.

[0071] The outer layer 72 can be formed, for example, by extruding a predetermined resin material onto the outer surface of the middle layer 68, with the outermost blade 74 positioned on the outer surface of the middle layer 68. The outer layer 72 may also be fused with the outer surface of the middle layer 68 in a molten state. The material of the outer layer 72 is not limited, and various resin materials can be used depending on the required characteristics; for example, polyamide resins such as Pebax can be used. It is also possible to integrate the middle layer 68 and the outer layer 72 using the same material, while it is also possible to improve the tuning flexibility of the catheter body 12 by using different materials for each.

[0072] In this embodiment, the catheter body 12, with its structure as described above, achieves improved torque transmission characteristics due to the presence of an outermost blade 74 that surrounds the entire outer circumference. In particular, the outermost blade 74 has a double-blade structure, which ensures the overall cross-sectional shape of the catheter body 12 and further improves torsional rigidity and torque transmission characteristics. As a result, for example, when the operator applies rotational force from the connector portion 16 or motor drive unit to adjust the opening direction of the window portion 36 of the cutter housing 26, the catheter body 12 rotates smoothly from the proximal end to the tip end, making it possible to set the opening direction of the window portion 36 stably and accurately.

[0073] Furthermore, since the second lumen 22 has a non-braided structure with its peripheral wall not reinforced with braids, the peripheral wall of the second lumen 22 does not become excessively thick, thus suppressing the increase in diameter of the catheter body 12, and making it easy to realize a small-diameter catheter. In this case, the peripheral wall of the second lumen 22 is formed with a large resin cross-sectional area in an integral thick-walled structure by the main body layer 66 (middle layer 68) that also covers the first tube 60 forming the first lumen 20. As a result, even with a non-braided structure, the strength of the peripheral wall of the second lumen 22 can be ensured, the cross-sectional shape of the second lumen 22 can be stabilized, and lumen collapse can be effectively prevented.

[0074] Furthermore, since the peripheral wall portion of the first lumen 20 is reinforced with blades, better cross-sectional shape stability can be obtained in the first lumen 20. For example, deformation due to the rotational drive reaction force of the cutter 32 can be prevented, and the stability of the rotational operation of the shaft 34 and the performance of rotational drive force transmission can also be improved.

[0075] In particular, in this embodiment, the overall torque transmission characteristics and deformation strength of the catheter body 12 are ensured by the fact that the outermost blade 74 has a double-blade structure, so that the inner blade 62 can have a single-blade structure while ensuring the required characteristics for the first lumen 20.

[0076] This prevents the thickness of the outer wall of the first lumen 20, and consequently the separation distance between the first lumen 20 and the second lumen 22, the outer diameter of the middle layer 68, and furthermore, the outer diameter of the catheter body 12 from becoming excessively large, thereby effectively reducing the overall diameter of the catheter body 12. In particular, as described above, since the portion of the outer wall of the first lumen 20 in which the inner braid 62 is embedded surrounding the thin-walled PTFE layer and the portion of the outer wall of the second lumen 22 share the middle layer 68, the diameter of the catheter body 12 can be effectively reduced compared to a conventional catheter structure in which, for example, two tubes (a tube for the first lumen and a tube for the second lumen) made of separately molded multilayer tubes are bundled and fixed together by another resin molding process.

[0077] Furthermore, the increased flexibility in setting the outer diameter of the catheter body 12 makes it possible to enlarge the second lumen, for example, which allows for faster inflation and deflation of the balloon 40 (expansion and contraction by supplying and releasing).

[0078] Furthermore, the catheter body 12 can be partially constructed differently in the longitudinal direction, taking into consideration that, for example, different characteristics are required for different parts in the longitudinal direction. Specifically, for example, the characteristics of the catheter body 12 can be partially adjusted by partially varying the material of the middle layer 68 and / or the outer layer 72 in the longitudinal direction. Alternatively, the characteristics of the catheter body 12 can be partially adjusted by partially varying the material, structure, number of windings (pitch) at a predetermined length, etc., of the inner braid 62 and / or the outermost braid 74 in the longitudinal direction.

[0079] For example, as shown in Figure 1, the distal end portion of the catheter body 12 may be reinforced with a braided structure of a predetermined length L to improve flexibility and other properties. A specific cross-sectional structure when flexibility and other properties are improved in the distal end portion is illustrated in Figure 4. That is, the distal end portion of the catheter body 12' shown in Figure 4 does not have the outermost braid 74. The distal end portion of the catheter body 12 differs only in the presence or absence of the outermost braid 74, and in Figure 4, members and parts with the same structure as in Figure 3 are given the same reference numerals as in Figure 3, and detailed explanations are omitted.

[0080] However, the methods for adjusting the partial structure and characteristics of the catheter body 12 in the longitudinal direction are not limited to the specific methods described above. For example, the proximal end portion of the catheter body 12 can also be made to have a structure similar to that shown in Figure 4, without the outermost blade 74, for a predetermined length, in order to improve procedural operability. Furthermore, when adopting a cross-sectional structure as shown in Figure 4 at the distal or proximal end of the catheter body 12, the length dimension (L) of the portion to which the cross-sectional structure is adopted is not limited. Specifically, a portion with a single-blade structure consisting only of the inner blade 62 without the outermost blade 74 can be set at the distal end and / or proximal end within a range of, for example, 50-300 mm. In particular, the single-braid structure can be set within a range of 100-200 mm at the distal end to adjust the bending characteristics of the catheter body 12, and the single-braid structure can be set within a range of 10-100 mm at the proximal end to easily realize a communication structure of the balloon port 48 to the second lumen 22 at the insertion portion inside the connector portion 16.

[0081] Furthermore, in the longitudinal direction of the catheter body 12, a buffer region having a single-braid outermost blade 74 may be provided for a predetermined length at the boundary between the region having the outermost blade 74 of the double-braid structure shown in Figure 3 and the region having the outermost non-braid structure shown in Figure 4, thereby allowing the characteristics of the catheter body 12 to change in steps along its length.

[0082] (2) Atherosclerotic ulcer treatment section 14 (tip section) The atherosclerotic ulcer treatment section 14 is equipped with a hollow cylindrical cutter housing 26 made of a hard material such as metal, as described above. As shown in Figure 7, the cutter housing 26 is abutted against the distal end of the catheter body 12 and connected in a communication state by an externally fitted proximal end connecting sleeve 78, which is fixed in place using adhesive or the like as needed.

[0083] Furthermore, a cylindrical insertion collar 82 made of a hard material is fitted to the proximal end portion of the cutter housing 26 and extends toward the interior of the catheter body 12. This insertion collar 82 forms a housing area for the proximal end shaft portion of the cutter 32.

[0084] Furthermore, a shaft 34, which is positioned to penetrate the first lumen 20 of the catheter body 12, extends into the insertion collar 82. The distal end of this shaft 34 is inserted into the central hole 84 of the cutter 32, and the distal end of the shaft 34 is fixed to the cutter 32 on the same central axis using fixing means such as adhesive or a fitting ring. As a result, the cutter 32 rotates integrally with the shaft 34, which is subjected to rotational driving force from the motor drive unit, and moves integrally in the central axis direction with the shaft 34, which is subjected to axial driving force from the advance / reverse controller 52.

[0085] Furthermore, as shown in Figure 6, the supply and discharge outlet portion 86 extending from the base end of the balloon 40 is inserted into the second lumen 22 through the opening at the distal end and sealed with adhesive or the like. This allows for the supply and discharge of liquid to and from the balloon 40 through the second lumen 22.

[0086] On the other hand, as shown in Figure 8, a hollow connecting collar 88 is fitted to the tip of the cutter housing 26 and positioned at the entrance of the nose cone 28. The hollow interior of the cutter housing 26 is connected to the aforementioned flexible tubular nose cone 28 via this connecting collar 88. The connection between the cutter housing 26 and the nose cone 28 via the connecting collar 88 is sealed and fixed in place by an adhesive layer 90 or the like.

[0087] The connecting collar 88 is made of a hard material such as metal and constitutes a guide wire support. Specifically, the connecting collar 88 comprises a cylindrical outer circumferential portion 92 and an inner circumferential portion 96 that is located approximately on the central axis and has a circular guide wire insertion hole 94.

[0088] Furthermore, the outer cylindrical portion 92 and the inner cylindrical portion 96 are integrally connected at one point in the circumferential direction by a connecting portion 98 that extends radially. In other words, an axial communication hole 100 is formed between the outer cylindrical portion 92 and the inner cylindrical portion 96 in the radial direction, spreading in an arc shape in the circumferential direction and penetrating axially.

[0089] Furthermore, a guide wire 56, which is inserted over the catheter body 12 in an over-the-wire manner, is inserted through the guide wire insertion hole 94 of the connecting collar 88. That is, as shown in Figure 7-11, the guide wire 56 is inserted through the hollow hole of the shaft 34, which extends into the cutter housing 26 through the first lumen 20 of the catheter body 12 and is fixed to the cutter 32, and is positioned to extend from the distal end of the shaft 34 further toward the tip.

[0090] The guide wire 56, which extends from the distal end of the shaft 34 into the cutter housing 26, is inserted into the guide wire insertion hole 94, which is an inner hole in the inner circumferential cylindrical portion 96 of the connecting collar 88, and extends further toward the tip, passing through the nose cone 28 and extending toward the tip from the tip tip 30, so that it can be inserted and removed. In this way, the guide wire 56, which extends along the central axis of the cutter 32 within the cutter housing 26, is inserted into the guide wire insertion hole 94 at the tip side of the cutter housing 26, thereby being supported in a stable position approximately on the central axis within the cutter housing 26.

[0091] In this way, the connecting collar 88 supports the guide wire 56 so that it extends approximately along the central axis within the cutter housing 26. As a result, the shaft 34 and subsequently the cutter 32, which are externally mounted to the guide wire 56, are able to rotate stably while maintaining their central axis, and are also able to be stably fed and moved axially along the central axis by the guide wire 56.

[0092] Here, the communication hole 100 in the connecting collar 88 extends along the outer surface of the inner cylindrical portion 96, along the outer circumference of the guide wire insertion hole 94 for a length of more than half a circumference in the circumferential direction. That is, as shown in Figures 9 and 10, both circumferential ends of the communication hole 100 extend in an arc-shaped curved form beyond the horizontal line passing through the center of the guide wire insertion hole 94 to below the inner cylindrical portion 96. The distance between the circumferential ends of the communication holes 100 located on both sides of the connecting portion 98 is the same as or smaller than the inner diameter of the guide wire insertion hole 94.

[0093] Thus, by forming the communication hole 100 with a roughly C-shaped cross-section having a circumferential length of more than half the circumference, a sufficiently large cross-sectional area perpendicular to the axis is set. As described above, in the region located on the proximal end side of the connecting collar 88 within the cutter housing 26, the atherosclerotic plaque excised by the cutter 32 and sent forward can pass through the communication hole 100 without significant resistance and be sent into the nose cone 28, which is the storage area for the excised atherosclerotic plaque.

[0094] In particular, as shown in Figures 9 and 10, both circumferential ends of the communication hole 100 are semicircular in shape, and the outer edge of the communication hole 100 has a smooth, curved shape without any sharp corners throughout. This makes it possible to further reduce the resistance to the passage of excised atherosclerotic plaque sent from inside the cutter housing 26 to inside the nose cone 28 through the communication hole 100, and to suppress the fragmentation of the excised atherosclerotic plaque, thereby reducing the risk of the excised atherosclerotic plaque becoming micronized and leaking into the blood vessels.

[0095] Furthermore, the axial base end surface of the connecting portion 98 (Figure 10) protrudes most towards the base end in the circumferential direction, and from there toward the circumferential ends of the communication holes 100 located on both sides in the circumferential direction, the circumferential inclined surfaces 108, 108 are gently sloped toward the tip on both sides in the circumferential direction. As a result, the excised plaque fed from inside the cutter housing 26 into the communication holes 100 is guided along the circumferential inclined surfaces 108, 108, and is led into the communication holes 100, reducing or avoiding pressure against the base end surface of the connecting portion 98, and thus further reducing the resistance to forward movement of the excised plaque and avoiding fragmentation of the excised plaque.

[0096] In addition, as shown in Figure 8, the axial base end surface of the connecting portion 98 includes the axial end surface of the inner circumferential cylinder portion 96 and is an axially inclined surface 110 that extends smoothly without steps from the guide wire insertion hole 94 radially outward (downward in the figure) toward the axial base end side (cutter 32 side). The guiding action of this axially inclined surface 110 allows the excised atherosclerotic plaque, which is sent from the base end toward the connecting portion 98, to be guided so as to be distributed throughout the entire circumferential direction of the communication hole 100, with reduced pressure against the base end side surface of the connecting portion 98. In particular, the mutual guiding action of the axially inclined surface 110 and the circumferentially inclined surfaces 108, 108 can be exerted to further reduce the resistance to the forward movement of the excised atherosclerotic plaque and further avoid fragmentation of the excised atherosclerotic plaque.

[0097] In particular, in this embodiment, the axial inclined surface 110 is a gently sloping surface in which the length dimension L is greater than the height dimension H (L > H), preferably the length dimension L is 1.5 times or more the height dimension H, and more preferably 2 times or more. Furthermore, the inclination angle of the axial inclined surface 110 may be substantially constant throughout, but as shown in Figure 8, the inclination is more gradual towards the base end than towards the tip end (left side in Figure 8), and a configuration in which the inclination angle gradually changes so that the inclination angle at the base end is substantially zero is preferably adopted.

[0098] Furthermore, in this embodiment, the radial width dimension t of the outer peripheral communication hole 100 is made smaller than the outer diameter of the guide wire 56 to prevent incorrect insertion of the guide wire 56, and the guide wire 56 can be easily inserted into the guide wire insertion hole 94 formed in the center, which has an inner diameter dimension larger than the outer diameter of the guide wire 56.

[0099] On the other hand, the axial end surface of the connecting portion 98 is also provided with an axial inclined surface 112 that extends smoothly from the guide wire insertion hole 94 radially outward (downward in Figure 8) towards the axial end (nose cone 28 side) without any steps, similar to the axial base surface. Furthermore, as shown in Figure 9, circumferential inclined surfaces 114, 114 are also provided on both sides of the connecting portion 98, circumferentially inclined surfaces 114, 114 that slope gently toward the end on both sides of the circumferential direction from the central part of the circumferential direction toward the circumferential ends of the communication holes 100 located on both sides of the circumferential direction.

[0100] Since these axially inclined surfaces 112 and circumferentially inclined surfaces 114, 114 on the tip side are provided on the axial tip side of the connecting portion 98, the excised atherosclerotic plaque guided from the communication hole 100 of the connecting portion 98 into the nose cone 28 is made smoother, and further reduction of movement resistance can be achieved.

[0101] As shown in Figure 8, in this embodiment, the inclined surfaces 110 and 112 on both axial sides of the connecting portion 98 are formed to include the axial end face of the inner circumferential cylindrical portion 96, so that the guide wire insertion hole 94 extends axially on both sides, particularly on the lower side in Figure 8. The inner circumferential surfaces on both axial sides of the extended guide wire insertion hole 94 are tapered to gradually increase in diameter toward the outward direction on both axial sides, thereby improving the ease of insertion of the guide wire 56 and reducing sliding resistance.

[0102] Furthermore, the inclined surface 110 on the axial base side of the connecting portion 98 extends significantly in the axial direction and is formed with a gentle and small inclination angle compared to the inclined surface 112 on the axial tip side. This effectively reduces the pressing force on the connecting portion 98 of the excised plaque as it is fed forward within the cutter housing 26, thereby improving the effect of suppressing movement resistance, while also efficiently securing the volume of the area for accommodating the excised plaque on the tip side of the connecting collar 88.

[0103] Furthermore, in this embodiment, a support hole 118 extending in the axial direction is formed in the portion of the connecting portion 98 that extends toward the tip and forms the tip-side axially inclined surface 112. A small-diameter rod-shaped support material 120 is fitted into this support hole 118 at its base end and fixed in place. This support material 120 extends straight along the inner circumferential surface of the nose cone 28 toward the tip to a predetermined length (for example, an intermediate position in the longitudinal direction), and supports the thin-walled nose cone 28 from the inner side to maintain its shape. The shape and material of the support material 120 are not limited, and for example, a spiral-shaped support material may be used. However, by using a rod-shaped support material 120 that extends linearly in the longitudinal direction as in this embodiment, it is possible to secure the volume for accommodating the excised plaque within the nose cone 28 and reduce the resistance to the excised plaque being fed into the nose cone 28. Furthermore, the support material 120 may be fixed to the nose cone 28, but in this embodiment, it is not fixed, thereby avoiding the concentration of stress and strain due to local constraint of the nose cone 28.

[0104] In this way, by forming the support holes 118 of the support material 120 on the circumferentially inclined surface at the tip side of the connecting collar 88 that extends toward the tip side, the length of the support holes 118 that support the support material 120 can be efficiently secured at a position that avoids adverse effects on the flow of plaque sent into the nose cone 28 through the communication hole 100.

[0105] Although embodiments of the present invention have been described in detail above, the present invention is not intended to be interpreted as being limited by the specific descriptions above.

[0106] For example, the structure of the catheter body 12 described in section (III)(1) above is not limited to catheters for atherosclerotic plaque removal as described in section (2), but can be applied to various catheters used in various sites and procedures.

[0107] Furthermore, the present invention is not limited to catheters with a double-lumen structure, but can also be applied to catheters having, for example, three or more lumens. The third, fourth, and other lumens may have a non-braided structure, or various braided structures may be appropriately adopted depending on the required characteristics.

[0108] Furthermore, the purpose and size of the first and second lumens can be appropriately set according to the type of procedure in which the catheter is used, and are not limited to these specifications.

[0109] Furthermore, the catheter body 12 can also incorporate various known configurations. For example, as described in Patent Document 2, a marker that can be confirmed during the procedure may be placed in an appropriate position, or a rod-shaped reinforcing member may be embedded.

[0110] Furthermore, the guide wire support constituting the guide wire insertion hole 94 may be made of a separate component as shown in the example, or it may be made of the same component as the cutter housing 26.

[0111] Furthermore, although not listed individually, the present invention can be implemented in various forms based on the knowledge of those skilled in the art, and such embodiments are all included within the scope of the present invention, as long as they do not depart from the spirit of the invention.

[0112] 10 Catheter 12, 12' Catheter body 14 Atherosclerotic cyst treatment section 16 Connector section 20 First lumen 22 Second lumen 26 Cutter housing 28 Nose cone 30 Tip 32 Cutter 34 Shaft 36 Window section 40 Balloon 44 Main housing 46 Flush port 48 Balloon port 50 MDU connection section 52 Advance / reverse controller 56 Guidewire 60 First tube 62 Inner braid 64 Inner protective layer (first lumen) 66 Main layer 68 Middle layer 70 Inner protective layer (second lumen) 72 Outer layer 74 Outermost braid 78 Proximal end connection sleeve 80 Proximal end connection sleeve 82 Insertion collar 84 Central hole (cutter) 86 Extension section 88 Connection collar (guidewire support) 90 Adhesive layer 92 Outer circumferential section 94 Guide wire insertion hole 96 Inner circumferential section 98 Connecting section 100 Communication hole 108 Circumferential inclined surface 110 Axial inclined surface 112 Axial inclined surface on the tip side 114 Circumferential inclined surface on the tip side 118 Support hole 120 Support material

Claims

1. A catheter comprising a first lumen having a blade surrounding its outer circumference, a second lumen not having a blade surrounding its outer circumference, and an outermost blade arranged on the outer circumference of the catheter body having the first and second lumens.

2. The catheter according to claim 1, wherein the peripheral wall of the first lumen is formed by a first tube, and the main body layer forming the second lumen covers the outer circumference of the first tube and is integrated with it.

3. The catheter according to claim 2, wherein the main body layer comprises an inner circumferential middle layer that covers the outer circumference of the first tube and forms the second lumen, and an outer layer that surrounds the outer circumference of the middle layer and on which the outermost blade is arranged.

4. The catheter according to any one of claims 1 to 3, wherein the blade surrounding the outer circumference of the first lumen has a single-blade structure, while the outermost blade has a double-blade structure.

5. The catheter according to any one of claims 1 to 3, wherein the cross-sectional area of ​​the first lumen is greater than the cross-sectional area of ​​the second lumen.

6. The catheter according to any one of claims 1 to 3, wherein a non-braided region is provided at the distal end in the longitudinal direction, where the outermost braid is not located.

7. The catheter according to any one of claims 1 to 3, wherein the catheter body is provided with a balloon at its distal end, and the balloon lumen for supplying and discharging expansion and contraction fluid to the balloon is configured by the second lumen.

8. The catheter according to any one of claims 1 to 3, wherein the catheter body is provided with a cutter at its distal end, and the shaft lumen through which a shaft that applies rotational driving force to the cutter is inserted is configured by the first lumen.

9. A catheter having a cutter positioned in a cylindrical housing at the distal end of the catheter body, wherein the cutter rotates and moves to cut atherosclerotic plaque that has entered the cylindrical housing through a window and deliver it into the nose cone at the front, wherein a guidewire support is provided at the entrance side of the nose cone to support a guidewire inserted through the cutter, the guidewire support having a guidewire insertion hole that penetrates the central part axially, and a communication hole that extends in an arc shape in the circumferential direction and penetrates the outer circumference of the guidewire insertion hole, for delivering the atherosclerotic plaque cut by the cutter into the nose cone, wherein the communication hole has curved ends that extend more than half a circumference around the wire insertion hole, and reaches a circumferential position where it wraps around the wire insertion hole from both sides in the circumferential direction and approaches each other.

10. The catheter according to claim 9, wherein the guidewire support comprises an outer cylindrical portion connected to the nose cone, an inner cylindrical portion constituting the circumferential wall of the guidewire insertion hole, and a connecting portion located between the circumferential ends of the communication hole and connecting the outer cylindrical portion and the inner cylindrical portion, wherein the proximal end surface of the connecting portion is formed with a circumferentially inclined surface that gradually slopes toward the tip toward the circumferential ends of the communication hole.

11. The catheter according to claim 9 or 10, wherein the guidewire support has an axially inclined surface formed on the proximal end surface between the circumferential ends of the circumferential portion of the communication hole, which extends smoothly toward the axial proximal end without any steps toward the radially outward direction from the guidewire insertion hole.

12. The catheter according to claim 9 or 10, wherein the guidewire support is made of metal.

13. The catheter according to claim 9 or 10, wherein the guidewire support has support holes formed therein that open toward the tip side between the circumferential ends of the communication hole, and a reinforcing member is provided that protrudes toward the tip side from the support holes.

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