WO2014059922A1

WO2014059922A1 - Catheter coupling with guide wire for intravascular delivery and manufacturing method thereof

Info

Publication number: WO2014059922A1
Application number: PCT/CN2013/085274
Authority: WO
Inventors: 徐世云; 张琳琳; 唐智荣; 罗七一; 杨海
Original assignee: 上海微创医疗器械（集团）有限公司
Priority date: 2012-10-16
Filing date: 2013-10-16
Publication date: 2014-04-24
Also published as: CN103721337B; CN103721337A

Abstract

Disclosed are a catheter (2) coupling with a guide wire (1) for intravascular delivery and a manufacturing method thereof, wherein an inner wall of the catheter (2) has a spiral layer (3). When the catheter (2) is pushed along the guide wire (1), the coupling area between the guide wire (1) and the catheter (2) is greatly reduced while ensuring the direction of movement of the guide wire (1), thus reducing the friction force between the inner wall of the catheter (2) and the guide wire (1) and improving the deliverability of the catheter (2).

Description

Catheter for intravascular pushing with guide wire and manufacturing method thereof

The present invention relates to catheters, and more particularly to catheters that are configured to be pushed in conjunction with a guidewire within an arterial vessel. Background technique

In the interventional treatment of coronary heart disease, percutaneous transluminal coronary angioplasty (PTCA) combined with stent implantation, the stenosis of the coronary lumen becomes larger, blood flow increases, blood supply improves . The specific procedure of coronary stent implantation is as follows: Percutaneous puncture of the femoral artery or iliac artery, the angiographic guide wire is retrogradely sent through the aorta to the opening of the aortic root coronary artery, and the contrast catheter is sent along the guide wire to exit the guide catheter. Wire, perform angiography, complete angiography, exit the contrast catheter, enter the contrast guide wire, follow the guide wire into the guiding catheter, exit the contrast guide wire, enter the smooth guide wire, and send it along the guiding catheter to the entrance of the coronary artery. Enter the coronary artery after exiting the catheter. The balloon catheter with the stent is placed on the guide wire, located in the guiding catheter cavity, and sent to the coronary lesion, and the balloon in the stent is filled with a certain pressure of contrast medium to fill, the stent is opened, and the stent is fixed. Stenosis of the lesion. Traditionally, the inner wall of the delivery catheter that cooperates with the smooth guidewire is of a smooth structure, and the frictional resistance is relatively large when the smooth guide wire is wrapped to the lesion, especially when the blood vessel is bent. In order to reduce the frictional resistance, a discontinuous structure treatment may be added to the surface of the guide wire. However, discontinuous structural processing can result in the following defects:

1. When pushing the balloon into the balloon dilation catheter along the guide wire, the catheter tip of the narrow opening (ie, the distal end of the catheter) may become stuck on the surface of the guide wire during the pushing process, resulting in difficulty in pushing; 2. During the insertion of the guide wire into the lesion, when the guide wire is out of the catheter port and enters the lesion, such as a stenotic coronary artery, its surface protrusion or discontinuous structure may increase propulsion resistance, even vascular tissue damage. And cause concurrency problems. The Chinese utility model patent CN2824973Y discloses a medical guide wire. The medical guide wire changes the cross section of the conventional circular guide wire into a triangle, a pentagon, a hexagon, a star, etc., and even has a threaded structure on the guide wire, so as to reduce the matching area of the guide wire of the catheter, thereby reducing Friction. However, considering that the guide wire is in the blood vessel, after the contrast catheter is taken out, it will be directly advanced in the lesion site, and often the site itself is narrow, and the change of the surface of the guide wire may increase the possibility of damaging the blood vessel. U.S. Patent 6,848,062 B2 discloses a catheter shaft for a balloon catheter. The catheter shaft changes a conventional smooth catheter into a star shape, and there are a plurality of (at least four) protrusion lines on the inner circumference of the catheter shaft, the plurality of protrusion lines running straight through the entire length of the catheter shaft, and the purpose is also to reduce the guide wire Contact area. But its disadvantages are:

1. The plurality of protrusion lines run straight through the entire length of the catheter shaft, and the contact between the guide wire and the catheter shaft is still continuous line contact, because a plurality of protrusion lines are required to limit the range of movement of the guide wire, thereby increasing friction;

2. At the bend, the guide wire may increase contact with the protrusion and the friction will still be large. Summary of the invention

SUMMARY OF THE INVENTION The object of the present invention is to provide a catheter for intravascular push with a guide wire and a method for manufacturing the same, which can greatly reduce the matching area of the guide wire and the catheter while ensuring the direction of movement of the guide wire while pushing the catheter along the guide wire. During the catheter advancement process, the friction between the inner wall of the catheter and the guide wire is reduced, and the pushability of the catheter is increased. The present invention provides a catheter for intravascular push with a guide wire, characterized in that the inner wall of the catheter has a spiral layer. Since the inner wall of the catheter has a spiral layer, the contact between the guide wire and the catheter is a discontinuous line contact or a point contact, and when the catheter is pushed along the guide wire, the guide wire is greatly reduced while the guide wire is moved. The mating area of the catheter reduces the friction between the inner wall of the catheter and the guide wire during catheter advancement, increasing the pushability of the catheter. At the same time, the present invention changes that the lumen surface structure of the catheter (the side of the guide wire) is less prone to advancement in advancement than the method of reducing the frictional area by changing the surface of the guidewire to reduce the fit area. Additional resistance. The helical layer may be distributed in any region between the two ends of the catheter. Preferably, the helical layer distribution covers the entire length of the catheter such that even if a condition of catching the guidewire occurs, it is easier to adjust at the beginning of the external guidewire rather than the body. For example, in a fast-switching balloon catheter, because the length of the catheter is short, after the catheter is placed on the guide wire in vitro, the guide wire will pass through the guide wire of the balloon catheter during the push, during the push. The smooth guidewire and catheter fit will remain unaltered and no additional obstruction to the catheter will occur. Preferably, the surface of the helical layer that is in contact with the guidewire is oriented toward the guidewire to further reduce the contact area of the guidewire with the catheter. More preferably, the cross section of the spiral layer facing the end of the guide wire protrusion in the axial direction of the catheter is curved or dot-shaped, so that the contact between the guide wire and the catheter is point contact, The contact area between the guide wire and the catheter is further reduced. In the case where the cross section of the spiral layer toward the end of the guide wire projection in the axial direction of the duct is curved, the spiral layer is less likely to wear and fall off. The width of the cross section of the spiral layer in the axial direction of the catheter is not limited as long as the width is ensured to be well bonded to the inner wall of the catheter. However, preferably, the width of the cross section of the spiral layer in the axial direction of the catheter gradually becomes smaller toward the guide wire. This can reduce the possibility of catching the guide wire. More preferably, the cross-sectional shape of the spiral layer is substantially curved, triangular, trapezoidal or other polygonal shape. Preferably, the surface of the spiral layer in contact with the guide wire has a coating for reducing friction. More preferably, the coating may comprise silicone; the coating may comprise a hydrophilic organic or a hydrophobic organic. Still more preferably, the hydrophobic organic substance comprises polytetrafluoroethylene (PTFE) or parylene (PARYLENE). The height of the spiral layer in the radial direction of the catheter is not limited, but is preferably slightly smaller than the radius of the guide wire. Preferably, the pitch L of the spiral layer is selected according to the following formula:

L<=2*sqrt(3r ^A 2+2R*r)

Where r is the guidewire radius, R is the minimum bend radius of the guidewire, and the height of the helical layer in the radial direction of the conduit is taken as r. Selecting the pitch L of the spiral layer according to the formula, the guide wire in the maximum bending state can contact the top of two adjacent threads of the spiral layer instead of only contacting between the two adjacent threads The trough is such that the guide wire in the maximum bending state forms a stable three-point contact with the catheter to smoothly guide the catheter. However, the pitch L should not be too small, because the pitch L is too small, the number of spiral turns increases, the contact area increases, and the friction increases. Preferably, the spiral layer is made of a hard material. More preferably, the hard material is a polymer material or a metal material. Further preferably, the hard material is an engineering plastic or an alloy. Still more preferably, the alloy is stainless steel or nickel titanium alloy. Still more preferably, the engineering plastic is a polyamide or a polyester. The present invention also provides a method of manufacturing the above-described catheter with a guide wire for intravascular push, the method comprising: preparing a hollow tubular substrate, the hollow tubular substrate serving as a catheter body; making a spiral operation wire, The outer diameter of the spiral of the operation wire is matched with the inner diameter of the hollow tubular substrate, the outer side of the operation wire has a groove, and the length of the operation wire in the axial direction is greater than the length of the hollow tubular substrate Making a spiral layer wire, the spiral layer wire being sized such that the spiral layer wire can be embedded in the groove; Embedding the spiral layer wire into the groove; applying a binder to the bottom of the spiral layer wire exposed from the groove; placing the operation wire embedded with the spiral layer wire The inner side of the hollow tubular substrate; and the bottom of the spiral layer filament is firmly bonded to the inner side surface of the hollow tubular substrate. The present invention also provides another method of manufacturing the above-described catheter with a guide wire for intravascular push, the method comprising: preparing a hollow tubular substrate, the hollow tubular substrate serving as a catheter body; The spiral layer wire is dimensioned such that the spiral outer diameter of the spiral layer filament is less than or equal to the inner diameter of the hollow tubular substrate; the spiral layer filament is placed inside the hollow tubular substrate; The hollow tubular substrate is coated on the spiral layer filament, and the spiral layer filament is embedded in the hollow tubular substrate to a depth smaller than a diameter of the spiral layer filament. DRAWINGS

Figure 1 (a) is a perspective view of a catheter for intravascular push with a guidewire in accordance with the present invention.

Fig. 1(b), Fig. 1(c), and Fig. 1(d) are partial cross-sectional views of the catheter, respectively showing a cross-sectional shape of a spiral having a substantially curved, triangular, or trapezoidal shape.

Fig. 2 is a schematic view of calculation of the maximum value of the pitch of the spiral layer.

Figure 3 (a) is a partial perspective view of a fast exchange balloon catheter to which the present invention is applied. Figure 3 (b), Figure 3 (c), Figure 3 (d) is a partial cross-sectional view of the inner tube of the fast-exchange balloon catheter (i.e., the catheter of the present invention), respectively showing a generally curved, triangular, trapezoidal shape The spiral layer profile shape.

Figure 4 is a general schematic of the balloon catheter. Description of the reference numerals

1 guide wire

2 catheter

3 spiral layer

4 guide wire mouth 5 far tube

6 contrast fluid cavity

7 Tip head

R guide wire minimum bending radius

r guide wire radius

L pitch specific embodiment

Referring to Figures 1, 3 and 4, the catheter 2 according to the present invention is used as an inner tube of a catheter such as a balloon catheter or a guiding catheter, which is in-vascularly pushed with a guide wire 1 having a spiral layer on the inner wall of the catheter 2. 3. Since the inner wall of the catheter 2 has the spiral layer 3, the contact between the guide wire 1 and the catheter 2 is a discontinuous line contact or a point contact, and when the catheter 2 is pushed along the guide wire 1, while ensuring the direction of movement of the guide wire The contact area of the guide wire 1 and the catheter 2 is greatly reduced, and the friction between the inner wall of the catheter 2 and the guide wire 1 is reduced during the advancement of the catheter 2, and the pushability of the catheter 2 is increased. At the same time, the present invention changes the inner cavity surface structure of the catheter 2 (one side of the guide wire 1), compared with the method of reducing the frictional force by changing the surface of the guide wire 1 to reduce the fitting area, It is not easy to have extra resistance. The spiral layer 3 may be distributed at the tip end of the catheter 2 (ie, the end closer to the guide port 4) to the tip 7 of the catheter (ie, the catheter 2 is further away from the guidewire 4) In the other area between the other end). Preferably, the distribution of the helical layer 3 covers the entire length of the catheter 2, such that even if the condition of the guide wire 1 is caught, it is easier to adjust at the beginning of the external guidewire 1 rather than the body. For example, in the fast-switching balloon catheter shown in Figure 3, because the length of the catheter 2 is short, after the catheter 2 is placed on the guide wire 1 in vitro, the guide wire 1 will guide the wire from the balloon catheter. The mouth 4 is worn out, and during the pushing process, the smooth guide wire 1 and the catheter 2 will remain unchanged without change, and the catheter 2 will not be used again. There are additional obstacles to happen. Referring to FIG. 1(b), FIG. 1(c), FIG. 1(d), preferably, the surface of the spiral layer 3 in contact with the guide wire 1 is protruded toward the guide wire 1, thereby further reducing the guide wire. 1 contact area with the catheter 2. More preferably, a cross section of the spiral layer 3 toward the end of the protrusion of the guide wire 1 in the axial direction of the catheter 2 is curved or dot-shaped, so that the contact between the guide wire 1 and the catheter 2 For point contact, the contact area of the guide wire 1 with the catheter 2 is further reduced. In the case where the cross section of the spiral layer 3 toward the end of the projection of the guide wire 1 in the axial direction of the catheter 2 is curved, the spiral layer 3 is less likely to wear off. The width of the cross section of the spiral layer 3 in the axial direction of the catheter 2 is not limited as long as the width is ensured to be well bonded to the inner wall of the catheter. However, preferably, the width of the cross section of the spiral layer 3 in the axial direction of the catheter 2 is gradually reduced toward the guide wire 1. This can reduce the possibility of catching the guide wire 1. More preferably, the cross-sectional shape of the spiral layer 3 is substantially curved, triangular, trapezoidal or other polygonal shape. Expression here

"Substantially" because the cross-sectional shape of the spiral layer 3 is not strictly required to be an arc, a triangle, a trapezoid or other polygons, for example, at the top of the triangular, trapezoidal cross-sectional shape shown in Fig. 1(c), Fig. 1(d). Can be rounded to an arc. Preferably, the surface of the spiral layer 3 that is in contact with the guide wire 1 has a coating for reducing friction. More preferably, the coating may comprise silicone; the coating may comprise a hydrophilic organic or a hydrophobic organic. Still more preferably, the hydrophobic organic coating comprises polytetrafluoroethylene (PTFE) or parylene (PARYLENE). The height of the spiral layer 3 in the radial direction of the catheter 2 is not limited, but is preferably slightly smaller than the radius of the guide wire 1. Preferably, the maximum value of the pitch L of the spiral layer 3 can be calculated with reference to FIG. In order to allow the guide wire 1 in the maximum bending state to still guide the catheter 2 stably, the guide wire 1 in the maximum bending state preferably contacts the top of the two adjacent threads of the spiral layer 3 It is not only in contact with the valley between the two adjacent threads, so that the guide wire 1 in the maximum bending state forms a stable three-point contact with the catheter 2 to smoothly guide the catheter 2. The pitch L shown in Fig. 2 is the maximum pitch Lmax. If the radius of the guide wire 1 is r, the minimum bending radius of the guide wire 1 (i.e., the bending radius of the guide wire 1 in the maximum bending state) is R, and the spiral layer 3 is in the radial direction of the catheter 2 The height is taken as r, then the following formula (1) is satisfied according to the Pythagorean theorem:

(Lmax/2) ^A 2+(R+r) ^A 2=(R+2r) ^A 2 (1)

Further derivation of equation (2) according to equation (1):

Lmax=2 * sqrt(3 r ^A 2+2R*r) (2)

In other words, the pitch L of the spiral layer is selected according to the following formula (3):

L<=2*sqrt(3r ^A 2+2R*r) (3) Preferably, the spiral layer 3 is made of a hard material. More preferably, the hard material is a polymer material or a metal material. Further preferably, the hard material is an engineering plastic or an alloy. Still more preferably, the alloy is stainless steel or nickel titanium alloy. Still more preferably, the engineering plastic is a polyamide or a polyester. As described above, the spiral layer 3 is made of a hard material having a hardness greater than that of the catheter 2. Therefore, it is preferable to separately manufacture the spiral layer 3 and the catheter body. For example, the manufacturing method of the catheter 2 may include: preparing a hollow tubular substrate, the hollow tubular substrate serving as a catheter body; making a spiral operation wire, a spiral outer diameter of the operation wire and an inner diameter of the hollow tubular substrate Matching, the outer side of the operating wire has a groove, and the length of the operating wire in the axial direction is greater than the length of the hollow tubular substrate; making a spiral layer wire, the size of the spiral layer wire is designed such that The spiral layer wire can be embedded in the groove; the spiral layer wire is embedded in the groove; and the bottom of the spiral layer wire exposed from the groove is coated with an adhesive; The operation wire in which the spiral layer wire is embedded is placed inside the hollow tubular substrate; and the bottom portion of the spiral layer wire is firmly bonded to the inner side surface of the hollow tubular substrate. The above method produces the catheter of the present invention by bonding the spiral layer filament to the hollow tubular substrate. However, the invention is not limited to this configuration. For example, the catheter of the present invention can also be fabricated by thermally bonding the helical layer to the hollow tubular substrate. Another method of manufacturing the catheter 2 may include: preparing a hollow tubular substrate, the hollow tubular substrate serving as a catheter body; making a spiral layer filament, the spiral layer filament being sized such that the spiral of the helical layer filament The outer diameter is less than or equal to the inner diameter of the hollow tubular substrate; the spiral layer filament is placed inside the hollow tubular substrate; the hollow tubular substrate is coated on the spiral layer by heat The depth of the spiral layer wire embedded in the hollow tubular substrate is smaller than the diameter of the spiral layer wire. The catheter 2 of the present invention can be applied to any catheter that cooperates with a guidewire for intravascular push. The use of the catheter of the present invention on a fast-exchange balloon catheter will be exemplarily described below in connection with Figures 3, 4, and it should be understood that the following description is not intended to limit the invention to the inner tube of a fast-exchange balloon catheter. In the embodiment shown in Figure 3, the minimum bending radius of the fast-exchange balloon catheter is 9 mm (model), the guide wire used is 0.014 inch diameter or 0.178 mm radius, and the pitch L should be calculated according to formula (3). Less than 3.633mm, take 3.6mm. If the inner tube 2 of the quick-exchange balloon catheter is made by gluing, the specific manufacturing process is as follows:

Preparing a hollow tubular substrate, the hollow tubular substrate serving as a catheter body; making a helical operation wire, the spiral outer diameter of the operation wire matching the inner diameter of the hollow tubular substrate, the outer side of the operation wire having The groove, the groove pitch L is calculated as 3.6 mm as described above, and the length of the operation wire in the axial direction is greater than the length of the hollow tubular substrate, that is, more than 250 mm or 70 turns of thread;

Making a spiral layer wire, the spiral layer wire being sized such that the spiral layer wire can be embedded in the groove;

Embedding the spiral layer wire into the groove; Applying an adhesive to the bottom of the spiral layer wire exposed from the groove;

Inserting the operation wire embedded with the spiral layer filament into the inner side of the hollow tubular substrate;

The bottom of the spiral layer filament is bonded to the inner side surface of the hollow tubular substrate. If the inner tube 2 of the quick-change balloon catheter is made by thermal bonding, the specific manufacturing process is as follows:

Preparing a hollow tubular substrate, the hollow tubular substrate being used as a catheter body;

Making a spiral layer wire, the spiral layer wire being dimensioned such that the spiral outer diameter of the spiral layer wire is less than or equal to the inner diameter of the hollow tubular substrate, and the pitch L of the spiral layer wire is calculated to be 3.6 mm as described above. And the length of the spiral layer wire in the axial direction is greater than the length of the hollow tubular substrate, that is, greater than 250 mm or 70 turns of thread;

Inserting the spiral layer filament into the inner side of the hollow tubular substrate;

The hollow tubular substrate is coated on the spiral layer filament by heat, and the depth of the spiral layer filament embedded in the hollow tubular substrate is smaller than the diameter of the spiral layer filament. In addition, the specific practices for the three different helical layer profiles shown in Figures 3(b), 3(c), and 3(d) are as follows:

A. The added thread profile is a hemispherical structure with a section radius of 0.17 mm. It is made of polyamide material and firmly bonded to the inner surface of the hollow tubular substrate.

B. The added thread profile is an isosceles triangle with a height of 0.17mm and a bottom width of 0.34mm. The apex is ground, sharpened, curved, and made of stainless steel and bonded to the inside surface of the hollow tubular substrate. .

C. The added thread profile is an isosceles trapezoid, the height is equal to 0.17mm, the long base is 0.34mm, the short bottom is 0.17mm, and the two corners of the short bottom are polished to make the short bottom middle middle and low on both sides. Curved, made of polyamide material. Long bottom edge bonded to hollow tubular substrate

Application of the invention in the manufacture of a fast exchange balloon catheter, in cooperation with a guidewire The inner wall of the tube increases the spiral layer of the structure claimed in the present invention, and while limiting the advancement direction of the catheter, the contact area between the catheter and the guide wire is greatly reduced, and the sliding friction resistance is reduced, thereby reducing the frictional resistance during advancement.

Claims

claims

1. A catheter used with a guidewire for intravascular pushing, characterized in that: the inner wall of the catheter has a spiral layer.

2. The catheter used with a guidewire for intravascular pushing according to claim 1, characterized in that: the spiral layer is distributed in any area between the two ends of the catheter.

3. The catheter used with a guidewire for intravascular pushing according to claim 2, characterized in that: the spiral layer distribution covers the entire length of the catheter.

4. The catheter used with a guide wire for intravascular pushing according to claim 1, characterized in that: the surface of the spiral layer in contact with the guide wire protrudes toward the guide wire.

5. The catheter for intravascular pushing with a guide wire according to any one of claims 1 to 4, characterized in that: the width of the cross section of the spiral layer in the axial direction of the catheter is oriented toward the guide wire. The silk gradually becomes smaller.

6. The catheter used with a guide wire for intravascular pushing according to claim 5, characterized in that: the cross-sectional shape of the spiral layer is generally arc, triangle, trapezoid or other polygon.

7. The catheter used with a guide wire for intravascular push according to any one of claims 1 to 4, characterized in that: the surface of the spiral layer in contact with the guide wire has a coating for reducing friction.

8. The catheter used with a guide wire for intravascular pushing according to claim 7, characterized in that: the coating includes silicone.

9. The catheter according to claim 7, which cooperates with the guide wire for intravascular pushing. Characteristics include: the coating includes hydrophilic organic matter or hydrophobic organic matter.

10. The catheter used with a guidewire for intravascular pushing according to claim 9, characterized in that: the hydrophobic organic substance includes polytetrafluoroethylene or parylene.

11. The catheter used with a guide wire for intravascular pushing according to any one of claims 1 to 4, characterized in that: the height of the spiral layer in the radial direction of the catheter is smaller than that of the guide wire. radius.

12. The catheter used with a guidewire for intravascular pushing according to any one of claims 1 to 4, characterized in that the pitch L of the spiral layer is selected according to the following formula:

L<=2*sqrt(3r ^A 2+2R*r)

Where r is the radius of the guide wire, R is the minimum bending radius of the guide wire, and the height of the spiral layer in the radial direction of the catheter is taken as r.

13. The catheter used with a guidewire for intravascular pushing according to any one of claims 1 to 4, characterized in that: the spiral layer is made of hard material.

14. The catheter used with a guide wire for intravascular pushing according to claim 13, characterized in that: the hard material is a polymer material or a metal material.

15. The catheter used with a guide wire for intravascular pushing according to claim 14, characterized in that: the hard material is engineering plastics or alloys.

16. The catheter used with a guidewire for intravascular pushing according to claim 15, characterized in that: the alloy is stainless steel or nickel-titanium alloy.

17. The catheter used with a guide wire for intravascular pushing according to claim 15, characterized in that: the engineering plastic is polyamide or polyester.

18. A method of manufacturing a catheter for intravascular pushing with a guidewire according to any one of claims 1 to 17, the method comprising:

Preparing a hollow tubular base material, the hollow tubular base material is used as the catheter body; Making a spiral operating wire, the spiral outer diameter of the operating wire matches the inner diameter of the hollow tubular base material, and the outside of the operating wire has groove, and the length of the operating wire in the axial direction is greater than the length of the hollow tubular base material;

Making a spiral layer filament, the size of the spiral layer filament is designed to enable the spiral layer filament to be embedded in the groove;

Embedding the spiral layer wire into the groove;

Apply adhesive to the bottom of the spiral layer wire exposed from the groove; Place the operating wire embedded with the spiral layer wire into the inside of the hollow tubular base material; and

The bottom of the spiral layer filament is firmly bonded to the inner surface of the hollow tubular base material.

19. A method of manufacturing a catheter for intravascular pushing with a guidewire according to any one of claims 1 to 17, the method comprising:

Preparing a hollow tubular base material, the hollow tubular base material being used as the catheter body; Making a spiral layer filament, the size of the spiral layer filament is designed such that the spiral outer diameter of the spiral layer filament is less than or equal to the diameter of the hollow tubular base material the inside diameter of;

Place the spiral layer wire inside the hollow tubular base material;

Through the action of heat, the hollow tubular base material is coated on the spiral layer filament, and the depth of the spiral layer filament embedded in the hollow tubular base material is less than the diameter of the spiral layer filament.