A coated balloon, a balloon catheter and a balloon catheter assembly

Abstract

The present invention relates to the field of medical device technology, and discloses a coated balloon, a balloon catheter, and a balloon catheter assembly. The coated balloon comprises: a balloon and a fiber braided layer. The fiber braided layer is coated on the outer surface of the balloon, and has a telescopic portion and a matching portion. The telescopic portion is located on a first side of the balloon, and the matching portion is located on a second side of the balloon opposite to the first side. When the balloon is inflated, the telescopic portion and the matching portion are suitable for bending in the same direction, and the extension length of the telescopic portion is greater than the extension length of the matching portion, so that the balloon bends. The coated balloon provided by the present invention has good pressure resistance and can bend and expand to adapt to the shape of curved human tortuous blood vessels. It can meet the surgical needs of tortuous blood vessel stenosis and expansion, and provides a favorable guarantee for the success of the operation.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a coated balloon, a balloon catheter and a balloon catheter assembly. Background Art

[0002] Balloon dilatation catheters have been widely used in the treatment of vascular stenosis in the human body. Due to the differences in elasticity of different blood vessels, conventional balloons cannot meet all balloon dilatation surgical needs, especially when the patient's blood vessels have severe calcification lesions. Conventional balloons cannot provide sufficient dilation pressure for the calcified blood vessels, making it difficult to expand the diseased blood vessels. The balloons may even be easily punctured by calcified lesions, causing injury to the vascular endothelium and leading to surgical failure.

[0003] In order to improve the pressure resistance of the balloon, a common method is to coat the surface of the balloon with a film to form a coated balloon. Although this method improves the structural strength of the outer surface of the balloon, it also reduces the elasticity of the outer surface of the balloon. In the process of dilating the stenosis of the human body's tortuous calcified blood vessels, the coated balloon is difficult to smoothly enter or pass through the human body's tortuous calcified blood vessels, and cannot meet the expansion needs of the stenosis of the human body's tortuous calcified blood vessels. If it forcibly enters or passes through the human body's tortuous calcified blood vessels, it will not only cause great pain to the patient, but may even cause damage or rupture of the inner wall of the blood vessel, resulting in failure of the operation. Summary of the invention

[0004] In view of this, the present invention provides a coated balloon, a balloon catheter and a balloon catheter assembly to solve the problem that conventional coated balloons cannot meet the needs of dilation surgery for tortuous calcified vascular stenosis lesions in the human body.

[0005] In a first aspect, the present invention provides a coated balloon, comprising:

[0006] Balloon;

[0007] The fiber woven layer is coated on the outer surface of the balloon and has a telescopic part and a matching part. The telescopic part is located on a first side of the balloon, and the matching part is located on a second side of the balloon opposite to the first side. When the balloon is inflated, the telescopic part and the matching part are suitable for bending in the same direction. The extended length of the telescopic part is greater than the extended length of the matching part, so that the balloon bends.

[0008] Optionally, the fiber woven layer includes first fibers and second fibers, a plurality of the first fibers are arranged at intervals on the outer surface of the balloon and extend in a direction parallel to the axial direction of the balloon, and the second fibers are spirally shaped and extend from the proximal end to the distal end on the outer surface of the balloon, wherein the plurality of first fibers located on the first side of the outer surface of the balloon have continuously curved segments, and the plurality of curved segments form the telescopic portion, and the plurality of first fibers located on the opposite side of the telescopic portion form the fitting portion.

[0009] Optionally, the second fibers are bonded to the outer surface of the balloon, the curved segment is not fixed to the outer surface of the balloon, and the first fibers except the curved segment are bonded to the outer surface of the balloon.

[0010] Optionally, the first fibers and the second fibers are fiber filament clusters formed by bundling a plurality of fiber filaments.

[0011] Optionally, the diameter of the fiber filaments ranges from 0.010 mm to 0.030 mm, and the tensile strength of the fiber filaments ranges from 3.0 GPa to 4.0 GPa.

[0012] Optionally, the fiber filaments are made of a high-strength fiber composited from one or more of poly(p-phenylene terephthalamide) fiber, aromatic polyamide copolymer fiber, heterocyclic polyamide fiber, carbon fiber, graphite fiber, and silicon carbide fiber.

[0013] In the second aspect, the present invention provides a balloon catheter, comprising a catheter and the above-mentioned coated balloon, wherein the coated balloon is arranged at the distal end of the catheter, and the balloon comprises a balloon expansion section located in the middle and cylindrical, a balloon distal connecting section and a balloon proximal connecting section located at the axial ends of the balloon expansion section and in a truncated cone shape, and the balloon distal connecting section and the balloon proximal connecting section are respectively connected to the catheter.

[0014] In a third aspect, the present invention provides a balloon catheter assembly, comprising the above-mentioned balloon catheter and a sleeve, wherein the catheter is located in the inner cavity of the sleeve, a tube expansion portion is provided at the distal end of the sleeve, and the coated balloon is suitable for contracting and entering the tube expansion portion.

[0015] Optionally, a diameter reducing portion is provided between the tube expansion portion and the sleeve, and the shape and size of the inner wall of the diameter reducing portion correspond to the shape and size of the outer wall of the proximal end of the coated balloon.

[0016] Optionally, the distal end of the expansion portion is provided with a chamfer.

[0017] Beneficial effects:

[0018] 1. The coated balloon provided by the present invention comprises: a balloon and a fiber braided layer. The fiber braided layer is coated on the outer surface of the balloon, and has a telescopic portion and a matching portion, the telescopic portion is located on a first side of the balloon, and the matching portion is located on a second side of the balloon opposite to the first side. When the balloon is filled, the telescopic portion and the matching portion are adapted to bend in the same direction, and the extended length of the telescopic portion is greater than the extended length of the matching portion, so that the balloon is bent.

[0019] The fiber braided layer can improve the pressure resistance of the outer surface of the balloon to adapt to calcified vascular lesions. When the coated balloon moves to the tortuous blood vessels of the human body, the balloon and the fiber braided layer covering the surface of the balloon are in a folded and contracted state to facilitate the coated balloon to enter the tortuous blood vessels of the human body. After the coated balloon moves to the lesion location, the balloon can be inflated. Since the extension length of the telescopic part is greater than the extension length of the matching part, the restraint forces on the opposite sides of the balloon are different. As the balloon is filled, the balloon expands and bends as a whole and dilates the tortuous blood vessels of the human body.

[0020] Therefore, the coated balloon provided by the present invention has good pressure resistance and can bend and expand according to the shape of curved human tortuous blood vessels, and can meet the surgical needs of expanding tortuous vascular stenosis lesions, providing a favorable guarantee for the success of the operation.

[0021] 2. The balloon catheter assembly provided by the present invention includes the above-mentioned balloon catheter equipped with the above-mentioned coated balloon, and also includes a sleeve, the catheter is located in the inner cavity of the sleeve, and a tube expansion part is provided at the distal end of the sleeve, and the coated balloon is suitable for shrinking and entering the tube expansion part.

[0022] Taking into account that the fiber woven layer of the coated balloon will encounter friction resistance when moving in the blood vessel, the coated balloon is retracted into the expansion part of the sheath. This arrangement allows the expansion part to contact the inner wall of the blood vessel instead of the coated balloon, thereby reducing the friction resistance between the coated balloon and the inner wall of the blood vessel. At the same time, it will not affect the bending performance of the coated balloon, thus facilitating the smooth movement of the balloon catheter equipped with the coated balloon in the blood vessel. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A schematic diagram of the structure of a coated balloon according to an embodiment of the present invention;

[0025] Figure 2 for Figure 1 A schematic structural diagram of the telescopic portion of the coated balloon shown;

[0026] Figure 3 for Figure 1 A schematic structural diagram of the matching portion of the coated balloon shown;

[0027] Figure 4 for Figure 1 The schematic diagram of the structure of the coated balloon shown is in a bent state;

[0028] Figure 5 It is a structural schematic diagram of a balloon catheter assembly according to an embodiment of the present invention;

[0029] Figure 6 for Figure 5 The cross-sectional structural schematic diagram of the balloon catheter assembly is shown.

[0030] Description of reference numerals:

[0031] 1. Balloon; 101. Balloon expansion section; 102. Balloon distal connection section; 103. Balloon proximal connection section; 11. Balloon tube leg; 2. Fiber braided layer; 201. Telescopic section; 202. Fitting section; 21. First fiber; 22. Second fiber; 211. Bending section; 3. Catheter; 4. Sleeve; 41. Expanding section; 42. Variable diameter section; 43. Chamfer. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention. In the embodiments of the present application, "proximal end" refers to the end closer to the operator, and "distal end" refers to the end farther from the operator.

[0033] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, in an embodiment of the present application, a coated balloon is provided, comprising: a balloon 1 and a fiber braided layer 2.

[0034] The middle part of the balloon 1 is cylindrical, and the proximal and distal ends of the balloon 1 are conical. Specifically, the balloon 1 includes a cylindrical balloon expansion section 101 located in the middle, a truncated cone-shaped balloon distal connecting section 102 and a balloon proximal connecting section 103 located at both axial ends of the balloon expansion section 101, the distal end of the balloon distal connecting section 102 is connected to the balloon leg 11, and the proximal end of the balloon proximal connecting section 103 is also connected to the balloon leg 11, and the two balloon legs 11 are respectively connected to the catheter. The balloon expansion section 101 can gradually expand as the amount of liquid or gas filled increases to dilate the blood vessel.

[0035] The fiber braided layer 2 is coated on the outer surface of the balloon 1, and the coverage includes the balloon expansion section 101, the balloon distal connection section 102 and the balloon proximal connection section 103 of the balloon 1. The fiber braided layer 2 has a telescopic portion 201 and a matching portion 202. The telescopic portion 201 is located on a first side of the balloon 1, and the matching portion 202 is located on a second side of the balloon 1 opposite to the first side. The telescopic portion 201 and the matching portion 202 are suitable for bending in the same direction. The extended length of the telescopic portion 201 is greater than the extended length of the matching portion 202, so that the balloon 1 bends. The same direction means that the telescopic portion 201 and the matching portion 202 can be bent at the same or similar angles. Taking the coated balloon as a whole as a reference, the matching portion 202 is concave and the telescopic portion 201 is convex, so that the coated balloon as a whole is curved to adapt to the shape of the inner wall of the tortuous blood vessel.

[0036] The fiber braided layer 2 can be deformed adaptively under the action of external force and recover after the external force is removed. The coated balloon is generally mounted at the distal end of the catheter, for example Figure 1 As shown, the balloon 1 can be sleeved on the distal end of the catheter 3. When in use, a guide wire can be inserted into the catheter 3 to guide the distal end of the catheter 3 to move. Before the coated balloon reaches the lesion position, the balloon 1 and the fiber braided layer 2 are in a folded and contracted state. After the coated balloon moves to the lesion position, as the balloon 1 is filled, the expansion force of the balloon 1 causes the telescopic part 201 and the matching part 202 of the fiber braided layer 2 to deform to varying degrees, and finally the fiber braided layer 2 constrains the balloon 1 to bend. When the balloon 1 needs to be withdrawn, the balloon 1 gradually decompresses and contracts, and the fiber braided layer 2 contracts synchronously until the balloon 1 and the fiber braided layer 2 are restored to a folded and contracted state.

[0037] The fiber braided layer 2 can improve the pressure resistance of the outer surface of the balloon 1 to adapt to calcified vascular lesions. When the coated balloon moves to the tortuous blood vessels of the human body, the balloon 1 and the fiber braided layer 2 coated on the surface of the balloon 1 are in a folded and contracted state, so that the coated balloon can enter the tortuous blood vessels of the human body. After the coated balloon moves to the lesion position, the balloon 1 can be filled. Since the extension length of the telescopic part 201 is greater than the extension length of the matching part 202, the restraint forces on the opposite sides of the balloon 1 are different. As the filling progresses, the balloon 1 expands and bends as a whole and dilates the tortuous blood vessels of the human body.

[0038] Therefore, the coated balloon provided in the present application has good pressure resistance and can bend and expand to adapt to the shape of the curved human body's tortuous blood vessels. It can meet the surgical needs of expanding tortuous blood vessel stenosis lesions, providing a favorable guarantee for the success of the operation.

[0039] It should be noted that the coated balloon provided by the present application is not only suitable for calcified diseased blood vessels, but also can be applied to blood vessels with thicker blood vessel walls and less elasticity. Compared with conventional balloons, the coated balloon of the present application has sufficient pressure resistance. In addition, the elastic modulus of the fiber braided layer 2 of the present application is greater than the elastic modulus of the balloon 1, so that the fiber braided layer 2 has sufficient restraint force on the balloon 1, so that the balloon 1 is curved under the joint action of the telescopic part 201 and the matching part 202.

[0040] like Figure 2 and Figure 3 As shown, in the present embodiment, the fiber braided layer 2 includes a first fiber 21 and a second fiber 22, and a plurality of first fibers 21 are arranged at intervals on the outer surface of the balloon 1 and extend in a direction parallel to the axial direction of the balloon. Specifically, in a natural state, the axial direction of the balloon 1 is a straight line, and the extension direction of the plurality of first fibers 21 is parallel to the axial direction of the balloon 1. The second fibers 22 are spiral and extend from the proximal end to the distal end on the outer surface of the balloon 1. The plurality of first fibers 21 and the plurality of second fibers 22 form an interlaced woven mesh structure, which can fully cover the outer surface of the balloon 1, and the elastic modulus of the first fibers 21 and the second fibers 22 are both greater than the elastic modulus of the balloon 1.

[0041] For example Figure 2 As shown, the multiple first fibers 21 located on the first side of the outer surface of the balloon 1 have a continuously bent curved segment 211, and the multiple curved segments 211 form a telescopic portion 201. The multiple curved segments 211 can change from a bent state to a straight state as the distal end of the balloon 1 moves toward or gradually fills, so that the telescopic portion 201 has a sufficient extension length. The telescopic portion 201 and the matching portion 202 can generate different restraining forces on the opposite sides of the balloon 1 to facilitate the balloon 1 to be filled into a bent state. When the balloon 1 is depressurized, the multiple curved segments 211 can gradually recover from a straight state to a bent state.

[0042] For example Figure 3 As shown, a plurality of first fibers 21 located on the opposite side of the telescopic portion 201 form a matching portion 202. The plurality of first fibers 21 constituting the matching portion 202 will not stretch or shorten, but will straighten or bend along the same direction in coordination with the telescopic portion 201, thereby jointly constraining the balloon 1 to a straightened state or a bent state.

[0043] In this embodiment, when the balloon 1 is in a natural state, all parts of the plurality of first fibers 21 except the curved section 211 are parallel to the axial direction of the balloon 1 , and the curved section 211 is continuously curved and extended along the axial direction of the balloon 1 .

[0044] like Figure 2As shown, in this embodiment, the second fiber 22 is bonded to the outer surface of the balloon 1, the curved section 211 is not fixed to the outer surface of the balloon 1, and the first fiber 21 except the curved section 211 is bonded to the outer surface of the balloon 1. This arrangement can ensure that most of the fiber woven layer 2 is fixed to the outer surface of the balloon 1 and shrinks or expands synchronously with the balloon 1. At the same time, it can also prevent the balloon 1 from moving in the fiber woven layer 2 and affecting the expansion effect of the fiber woven layer 2. The curved section 211 is not fixed to the outer surface of the balloon 1, which can ensure that the curved section 211 can be freely straightened or bent, and ensure that the coated balloon as a whole can be freely bent or straightened.

[0045] In this embodiment, the first fiber 21 and the second fiber 22 are fiber clusters formed by bundling multiple fiber filaments. The number of fiber filaments constituting the first fiber 21 and the second fiber 22 can range from 3 to 100. The more fiber filaments there are, the greater the elastic modulus of the fiber braided layer 2 and the better the pressure resistance. The fewer fiber filaments there are, the smaller the elastic modulus of the fiber braided layer 2 and the smaller the size. It can be set according to the properties of the inner wall of different blood vessels, thereby adaptively changing the pressure resistance and size of the fiber braided layer 2.

[0046] In this embodiment, the diameter of the fiber filaments ranges from 0.010 mm to 0.030 mm, the tensile strength of the fiber filaments ranges from 3.0 GPa to 4.0 GPa, and the mesh size ranges from 200 μm to 800 μm formed by weaving the first fibers 21 and the second fibers 22 on the fiber braided layer 2.

[0047] In this embodiment, the material of the fiber filament is a high-strength fiber composited with one or more materials selected from poly(p-phenylene terephthalamide) fiber, aromatic polyamide copolymer fiber, heterocyclic polyamide fiber, carbon fiber, graphite fiber, and silicon carbide fiber.

[0048] In this embodiment, the material of the balloon is a polymer material, which may include one or more of polyvinyl chloride (PVC), polyethylene (PE), polyurethane (TPU), polyamide material (Nylon), polyether block polyamide (Pebax) material and polyethylene terephthalate (PET) and the like.

[0049] like Figure 1 and Figure 4 As shown, the present application provides a balloon catheter, including a catheter 3 and the above-mentioned coated balloon, the coated balloon is arranged at the distal end of the catheter 3, the balloon 1 includes a balloon expansion section 101 located in the middle and cylindrical, a balloon distal connecting section 102 and a balloon proximal connecting section 103 located at the axial ends of the balloon expansion section 101 and in a truncated cone shape, the balloon distal connecting section 102 and the balloon proximal connecting section 103 are respectively connected to the catheter 3.

[0050] Similar to the structure described above, the distal end of the balloon distal connecting section 102 is connected to a balloon leg 11 , and the proximal end of the balloon proximal connecting section 103 is also connected to a balloon leg 11 , and the two balloon legs 11 are respectively connected to the catheter 3 .

[0051] The catheter 3 may have multiple channels, such as a guidewire channel and a charging channel. The distal end of the catheter 3 may have a tube opening to facilitate the guidewire to extend from the distal end of the guidewire channel and extend from the proximal end to guide the movement of the catheter 3. The charging channel is connected to the inner cavity of the balloon 1 to facilitate the external charging equipment to fill the balloon 1 with liquid or gas through the charging channel.

[0052] The structure, composition, connection relationship and function of the fiber braided layer 2 in this embodiment are exactly the same as the structure, composition, connection relationship and function of the fiber braided layer 2 described above, and will not be repeated here.

[0053] Considering that the fiber braided layer 2 of the coated balloon will increase the roughness of the outer surface of the balloon 1, resulting in greater friction resistance when the coated balloon moves in the blood vessel, in order to overcome the above problem and ensure that the coated balloon moves smoothly in the blood vessel, Figure 5 and Figure 6 As shown, the present application provides a balloon catheter assembly, including the above-mentioned balloon catheter, and also includes a sleeve 4, the catheter 3 is located in the inner cavity of the sleeve 4, the distal end of the sleeve 4 is provided with a tube expansion portion 41, and the coated balloon is suitable for shrinking and entering the tube expansion portion 41.

[0054] Before the coated balloon is introduced into the human body, the sleeve 4 can be sleeved on the catheter 3, and the coated balloon can be put into the expansion part 41 of the sleeve 4. The balloon 1 and the fiber braided layer 2 can be wrinkled and extended into the expansion part 41, and the outer surface of the fiber braided layer 2 is in contact with the inner wall of the expansion part 41. This arrangement allows the expansion part 41 to contact the inner wall of the blood vessel instead of the coated balloon, thereby reducing the friction resistance between the coated balloon and the inner wall of the blood vessel, and at the same time will not affect the bending performance of the coated balloon, so that the balloon catheter equipped with the coated balloon can move smoothly in the blood vessel. After moving to the lesion location, the sleeve 4 can be withdrawn. As the balloon 1 is gradually filled, the balloon 1 gradually bends under the constraint of the fiber braided layer 2 and expands the inner wall of the lesion blood vessel.

[0055] like Figure 5 and Figure 6 As shown, in this embodiment, a reducing portion 42 is provided between the expansion portion 41 and the sleeve 4, and the shape and size of the inner wall of the reducing portion 42 correspond to the shape and size of the outer wall of the proximal end of the coated balloon. On the one hand, it can improve the stability of the contracted coated balloon 1, and on the other hand, it can reduce the size of the outer edge of the sleeve 4, so as to facilitate the smooth movement of the sleeve 4 in the blood vessel.

[0056] like Figure 5 and Figure 6As shown, in this embodiment, the distal tube opening of the expansion part 41 is provided with a chamfer 43, the inclination of the chamfer 43 corresponds to the inclination of the distal surface of the coated balloon, thereby improving the smoothness of movement of the distal tube opening of the expansion part 41.

[0057] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A coated balloon, characterized in that: include: Balloon (1); The fiber braided layer (2) is coated on the outer surface of the balloon (1), and comprises a telescopic portion (201) and a matching portion (202), wherein the telescopic portion (201) is located on a first side of the balloon (1), and the matching portion (202) is located on a second side of the balloon (1) opposite to the first side, and when the balloon (1) is filled, the telescopic portion (201) and the matching portion (202) are adapted to bend in the same direction, and the extended length of the telescopic portion (201) is greater than the extended length of the matching portion (202), so that the balloon (1) is bent; The fiber braided layer (2) comprises first fibers (21) and second fibers (22), wherein a plurality of the first fibers (21) are arranged at intervals on the outer surface of the balloon (1) and extend in a direction parallel to the axial direction of the balloon (1), and the second fibers (22) are spirally shaped and extend from the proximal end to the distal end of the outer surface of the balloon (1), wherein the plurality of first fibers (21) located on a first side of the outer surface of the balloon (1) have a continuously curved section (211), and the plurality of the curved sections (211) form the telescopic portion (201), and the plurality of first fibers (21) located on a side opposite to the telescopic portion (201) form the matching portion (202); The second fibers (22) are bonded to the outer surface of the balloon (1), the curved section (211) is not fixed to the outer surface of the balloon (1), and the first fibers (21) other than the curved section (211) are bonded to the outer surface of the balloon (1).

2. The coated balloon according to claim 1, characterized in that: The first fibers (21) and the second fibers (22) are fiber filament clusters formed by bundling a plurality of fiber filaments.

3. The coated balloon according to claim 2, characterized in that: The diameter of the fiber filaments ranges from 0.010 mm to 0.030 mm, and the tensile strength of the fiber filaments ranges from 3.0 GPa to 4.0 GPa.

4. The coated balloon according to claim 2, characterized in that: The fiber filaments are made of high-strength fibers composited from one or more materials selected from aromatic polyamide copolymer fibers, heterocyclic polyamide fibers, carbon fibers, and silicon carbide fibers.

5. A balloon catheter, characterized in that: The invention comprises a catheter (3) and a coated balloon according to any one of claims 1 to 4, wherein the coated balloon is arranged at the distal end of the catheter (3), and the balloon (1) comprises a balloon expansion section (101) located in the middle and in a cylindrical shape, a balloon distal connection section (102) and a balloon proximal connection section (103) located at both axial ends of the balloon expansion section (101) and in a truncated cone shape, and the balloon distal connection section (102) and the balloon proximal connection section (103) are respectively connected to the catheter (3).

6. A balloon catheter assembly, characterized in that: The balloon catheter according to claim 5 further comprises a sleeve (4), wherein the catheter (3) is located in the inner cavity of the sleeve (4), a tube expansion portion (41) is provided at the distal end of the sleeve (4), and the coated balloon is suitable for contracting and entering the tube expansion portion (41).

7. The balloon catheter assembly according to claim 6, characterized in that: A diameter reducing portion (42) is provided between the expansion portion (41) and the sleeve (4), and the shape and size of the inner wall of the diameter reducing portion (42) correspond to the shape and size of the outer wall of the proximal end of the coated balloon.

8. The balloon catheter assembly according to claim 6, characterized in that: The distal end of the expanded tube portion (41) is provided with a chamfer (43).

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