Medical devices and methods for manufacturing medical devices

Abstract

This invention provides a medical device and a method for manufacturing the same, which have increased strength at the connection point between the tip tube and the base shaft at the proximal end. [Solution] A medical device 10 having a tip tube 20 and a base shaft 30 extending from the tip tube 20 toward the proximal end, wherein the tip tube 20 has an inner layer 40 facing an inner lumen 26 along the longitudinal axis, and the base shaft 30 has a tapered tip 32 whose outer diameter tapers toward the tip and is embedded in the inner layer 40.

Description

Technical Field

[0001] The present invention relates to a medical device having a distal tube at the distal end side and a base shaft at the proximal end side, and a method for manufacturing the same.

Background Art

[0002] A guiding catheter is used to guide a therapeutic catheter (such as a balloon catheter or a stent implantation catheter) for performing treatment, diagnosis, etc. by inserting it into a living body lumen such as a blood vessel to the target site.

[0003] For example, in percutaneous coronary angioplasty (PTCA), which is a treatment for coronary arteries, a guide wire for a guiding catheter is inserted into an artery from the skin of the wrist or thigh to reach the entrance of the coronary artery. Next, the guiding catheter is inserted into the artery along the guide wire, and then the guide wire for the guiding catheter is removed and engaged with the coronary ostium. A thinner guide wire for the therapeutic catheter is inserted into the lumen of the guiding catheter to pass through the lesion in the coronary artery. After that, a balloon catheter is inserted along the guide wire for the therapeutic catheter, the tip of the balloon catheter is protruded from the tip opening of the guiding catheter, and it is advanced peripherally in the coronary artery along the guide wire that has passed through the lesion. The balloon is placed at the lesion and the balloon is expanded to perform treatment.

[0004] After engaging the tip of the guiding catheter with a predetermined site (for example, the coronary ostium), a guide extension catheter may be used to smoothly advance the therapeutic catheter from the tip opening of the guiding catheter through the curved or bent coronary artery to the lesion. That is, the guide extension catheter can be inserted closer to the lesion than the guiding catheter, and furthermore, it can provide a stable backup force to the therapeutic catheter.

[0005] A guide extension catheter is a medical device with an intermediate opening, a so-called rapid exchange type guiding catheter, which has a tip tube that moves within the lumen of the guiding catheter and can protrude from the tip opening of the guiding catheter towards the tip, and a linear base shaft connected to the tip tube and extending from the tip tube towards the proximal end. In this case, the intermediate opening is the proximal opening of the tip tube. Because the base shaft is at the proximal end of the tip tube of the guide extension catheter, the length of the tubular portion (tip tube) is short. Therefore, even with a guide wire inserted inside the guiding catheter, it is easy to insert and remove the guide extension catheter along the guide wire without removing the guide wire.

[0006] When inserting a guide extension catheter into a guiding catheter and advancing its tip to the vicinity of a lesion, a dilator may be inserted into the lumen of the guide extension catheter to support passage through narrow or rigid parts of the blood vessel. This dilator, like the guide extension catheter, is a medical device with an intermediate opening, consisting of a tubular dilator tip tube and a dilator base shaft connected to the dilator tip tube and extending from the dilator tip tube toward the proximal end. It is a so-called rapid exchange type dilator.

[0007] Examples of medical devices, such as guide extension catheters and dilators, which consist of a tube at the tip and a base shaft at the proximal end, include those listed in Patent Document 1. In this medical device, the tip of the base shaft is embedded and fixed within the tube at the tip. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] U.S. Patent No. 9,352,123 [Overview of the project] [Problems that the invention aims to solve]

[0009] Medical devices having a tube at the tip and a base shaft at the proximal end require high strength at the connection point between the tube and the base shaft. If the strength of the connection point is low, the medical device may detach at the connection point when inserted into a biological lumen.

[0010] The present invention was made to solve the above-mentioned problems, and aims to provide a medical device and a method for manufacturing the same that have increased strength at the connection portion between the tip tube and the base shaft at the proximal end. [Means for solving the problem]

[0011] (1) A medical device that achieves the above objective is a medical device having a tip tube and a base shaft extending from the tip tube toward the proximal end, wherein the tip tube has an inner layer facing a lumen along the longitudinal direction, and the base shaft has a tapered tip portion toward the tip, with the outer diameter tapering toward the tip end, and is embedded in the inner layer.

[0012] A method for manufacturing a medical device that achieves the above objective (4) is a method for manufacturing a medical device having a tip tube and a base shaft extending from the tip tube toward the proximal end, comprising the steps of: forming an inner layer having a lumen along the longitudinal axis; laser welding the tip of the base shaft, which is coated on its surface with a resin fused to the inner layer, to the surface of the inner layer; and forming an outer layer on the outside of the inner layer. [Effects of the Invention]

[0013] In the medical device configured as described above, the base shaft is embedded in the inner layer, which allows for increased connection strength between the tip tube and the base shaft. Furthermore, because the base shaft of the medical device has a tip section embedded in the inner layer, the tip tube does not protrude outward at the connection point with the base shaft, allowing for a smaller outer diameter of the tip tube and improved passage through the body.

[0014] (2) In the medical device described in (1) above, the medical device may have an outer layer on the outer circumference side of the inner layer, the inner layer having a protruding portion that extends toward the outer layer, and the base shaft embedded in the protruding portion. This makes it possible to embed the base shaft on the outer circumference side of the inner layer while ensuring the thickness between the base shaft and the outer surface of the outer layer, and to firmly connect the base shaft to the tip tube without increasing the outer diameter of the tip tube.

[0015] (3) In the medical device described in (1) or (2) above, the inner layer may be made of a fluororesin. This improves the sliding properties of the guide wire or other devices inserted into the lumen, while also increasing the connection strength of the base shaft to the tip tube.

[0016] The manufacturing method for the medical device configured as described above involves embedding the base shaft in the inner layer to connect it to the tip tube, thereby forming the medical device without increasing the outer diameter of the tip tube.

[0017] (5) In the method for manufacturing the medical device described in (4) above, the resin may be made of the same material as the inner layer. This ensures that the base shaft and the inner layer are securely integrated.

[0018] (6) In the method for manufacturing the medical device according to (4) or (5) above, in the step of laser welding, a wavelength of the laser may be used such that the resin of the inner layer or a resin that can be fused with the inner layer is more easily absorbed than the material of the base shaft. Thereby, the base shaft can be surely embedded and fixed to the inner layer.

Brief Description of the Drawings

[0019] [Figure 1] It is a plan view of the medical device according to this embodiment. [Figure 2] It is a partially enlarged view near the tip tube of the medical device. [Figure 3] It is a partially enlarged cross-sectional view on the proximal end side of the tip tube of the medical device. [Figure 4] It is a cross-sectional view taken along line A-A of FIG. 3. [Figure 5] It is a cross-sectional view showing the manufacturing process of the medical device, and is an exploded view of the formed inner layer and the base shaft with the base end portion coated. [Figure 6] It is a cross-sectional view of the state where the base shaft is welded to the inner layer. [Figure 7] It is an enlarged bottom view near the connection portion between the inner layer and the base shaft when the base shaft is welded to the inner layer in a dot pattern.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the dimensional ratios in the drawings may be exaggerated for convenience of explanation and may be different from the actual ratios. In this specification, the side for inserting the device into the blood vessel will be referred to as the "tip side", and the side for operation will be referred to as the "base end side".

[0021] The medical device 10 according to this embodiment is a guide extension catheter. The guide extension catheter is inserted into a guiding catheter (not shown) and protrudes from the tip opening of the guiding catheter. It is used to extend a tube from the guiding catheter toward the tip for guiding a therapeutic catheter (not shown).

[0022] As shown in Figures 1 and 2, the medical device 10 comprises a tubular tip tube 20 and a linear base shaft 30 connected to the base end of the tip tube 20 and extending from the tip tube 20 toward the base end.

[0023] The tip tube 20 can move within the lumen of the guiding catheter and protrude from the tip opening of the guiding catheter toward the tip. This allows the tip tube 20 to provide a lumen continuous with that of the guiding catheter. In other words, during the procedure, the tip tube 20 of the medical device 10 can be inserted closer to the lesion than the guiding catheter, providing a stable backup force to the therapeutic catheter.

[0024] The tip tube 20 is a tubular body having a lumen that penetrates from the tip to the base, and comprises a tubular portion 22 located on the tip side and a semi-tubular portion 24 located on the base end side of the tubular portion 22. The tubular portion 22 is formed in a circular shape by providing material in a range of 360 degrees in the circumferential direction. The semi-tubular portion 24 is formed in a half-pipe shape by providing material in a range of approximately 180 degrees in the circumferential direction. The angular range in which the material for the semi-tubular portion 24 is provided is not particularly limited as long as it is less than 360 degrees, for example it may be less than 180 degrees. Also, the semi-tubular portion 24 may not be provided, or it may have an opening cut at an angle. The axial length of the tubular portion 22 is not particularly limited, but for example it is 50 mm to 1000 mm, preferably 200 mm to 400 mm. The axial length of the semi-tubular portion 24 is not particularly limited, but for example it is 5 mm to 900 mm, preferably 5 mm to 200 mm. The inner diameter of the tip tube 20 is not particularly limited, but is, for example, 0.3 mm to 2.0 mm, preferably 1.3 mm to 2.0 mm if it is a guide extension catheter, and 0.3 mm to 1.3 mm if it is a rapid exchange type dilator. The outer diameter of the tip tube 20 is not particularly limited, but is, for example, 0.7 mm to 2.2 mm, preferably 1.4 mm to 2.2 mm if it is a guide extension catheter, and 0.7 mm to 2.2 mm if it is a rapid exchange type dilator.

[0025] Preferably, the rigidity of the tip tube 20 decreases gradually or in stages from the base end to the tip end. This allows the tip tube 20 to become more flexible towards the tip, thus providing flexibility to the tip while maintaining high pushability at the base end. However, the rigidity of the tip tube 20 does not necessarily have to change from the base end to the tip end. The tip tube 20 has a tip 20a at its very tip, which is formed of, for example, a flexible material. Alternatively, in the case of a rapid exchange type dilator, the tip tube 20 may be tapered.

[0026] The tip tube 20 has a reinforcing layer 42 inside. The reinforcing layer 42 is formed by a coil in which at least one wire is wound spirally, or by multiple blades in which multiple wires are braided together, in order to reinforce the tubular portion 22 of the tip tube 20. The coil or blade is formed from wire made of a metal material such as stainless steel or tungsten wire, and the cross-sectional shape of the wire can be round, elliptical, oblong, rectangular, etc., and the diameter, width and thickness of the wire are not particularly limited and can be set as appropriate. Alternatively, in the case of a rapid exchange type dilator, the tip tube 20 may be a single layer made of a single material, or it may consist only of an inner layer and an outer layer, or the inner layer and outer layer may be made of the same material.

[0027] As shown in Figure 3, the tip tube 20 has an inner layer 40 that forms the inner circumferential surface of the tubular portion 22 and the semi-tubular portion 24 and faces the lumen 26, and an outer layer 41 that covers the outer circumferential side of the inner layer 40. The reinforcing layer 42 is placed between the inner layer 40 and the outer layer 41.

[0028] The inner layer 40 is preferably formed of a low-friction material to facilitate the sliding of the guide wire, therapeutic catheter, and dilator inside. The low-friction material is, but is not limited to, fluorine-based resins such as PTFE (polytetrafluoroethylene) and PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer) or silicone resins. The thickness of the inner layer 40 is not particularly limited, but for a guide extension catheter, it is, for example, 0.0001 mm to 0.1 mm, preferably 0.005 mm to 0.05 mm, and more preferably 0.01 mm to 0.03 mm. Alternatively, for a rapid-exchange type dilator, the thickness of the inner layer 40 is, for example, 0.01 mm to 1.0 mm, preferably 0.2 mm to 0.6 mm, and more preferably 0.3 mm to 0.5 mm.

[0029] The constituent material of the outer layer 41 is not particularly limited, but examples include various thermoplastic elastomers such as styrene-based, polyolefin-based, polyurethane-based, polyester-based, polyamide-based, polybutadiene-based, trans-polyisoprene-based, fluororubber-based, and chlorinated polyethylene-based materials, as well as polyether ketones and polyimides. One or more of these can be used in combination (polymer alloys, polymer blends, laminates, etc.). Alternatively, polyurethane elastomers, polyester elastomers, polyamide elastomers, etc., can be suitably used among the various elastomers.

[0030] The base shaft 30 is a flexible wire, which may be a round wire, a flat wire, or an arc-shaped wire, but a round wire is preferred, and is connected to the tip tube 20 and extends from the tip tube 20 toward the proximal end. The base shaft 30 may be coated with a low-friction material on all or at least part of the portion exposed to the outside so as to slide with low friction against the inner wall surface of the guiding catheter. The low-friction material is, for example, a fluororesin or a silicone resin, but is not limited to these. To improve the sliding properties of the base shaft 30 against the inner wall surface of the guiding catheter, the base shaft 30 may be coated with a lubricating material on all or at least part of the portion exposed to the outside, and a tapered portion may be provided in part.

[0031] In this embodiment, the outer diameter of the base shaft 30 is not particularly limited and can be set in the range of, for example, 0.05 mm to 1 mm. For a guide extension catheter, the outer diameter of the base shaft 30 is set to 0.5 mm to 0.7 mm, and for a rapid exchange type dilator, it is set to, for example, 0.3 mm to 1.0 mm, preferably 0.4 mm to 0.8 mm, and more preferably 0.5 mm to 0.7 mm. The constituent material of the base shaft 30 is not particularly limited, but stainless steel, nickel-titanium alloy, etc., can be suitably used. Furthermore, the cross-sectional shape of the base shaft 30 is not limited to a circle and may be rectangular, square, elliptical, etc., and may differ depending on the part. The base shaft 30 may have a depth marker on the proximal end that can be visually confirmed in order to determine the insertion length into the guiding catheter.

[0032] As shown in Figure 3, the base shaft 30 has a tapered tip 32 at the end where it connects to the tip tube 20, with its outer diameter tapering toward the tip. The tapered tip 32 is embedded in a protruding portion 44 that is integrated with the inner layer 40. The protruding portion 44 is made of a material that can be fused with the inner layer 40 or the same material. As shown in Figure 4, the protruding portion 44 protrudes from the inner layer 40 toward the outer layer 41, and the outer circumference of the protruding portion 44 is covered by the outer layer 41. The protruding portion 44 extends from the base end of the inner layer 40 toward the base end. The base shaft 30 is embedded in the inner layer 40 by being positioned in the protruding portion 44 that is integrated with the inner layer 40. The fact that the base shaft 30 is embedded in the protruding portion 44 that is integrated with the inner layer 40 increases the connection strength between the base shaft 30 and the tip tube 20. If it is a rapid exchange type dilator, it may be embedded in the tip tube 20 without providing an overhang 44.

[0033] Since the base shaft 30 has a tapered tip that connects to the tip tube 20, the base shaft 30 and the tip tube 20 can be connected without increasing the outer diameter of the tip tube 20. Furthermore, since the base shaft 30 is embedded in the inner layer 40, sufficient wall thickness can be secured between the base shaft 30 and the outer surface of the tip tube 20, thus preventing the outer diameter of the tip tube 20 from increasing.

[0034] Next, the manufacturing method of the medical device 10 will be described. As shown in Figure 5, first, a tubular body 46 that will become the inner layer 40 of the tip tube 20 is formed. In addition, a base shaft 30 is formed, and a coating portion 34 is formed by covering the tip portion of the base shaft 30, including the tip portion 32, with the same material as the inner layer 40. In this embodiment, the inner layer 40 and the coating portion 34 are made of PTFE (polytetrafluoroethylene). The length of the coating portion 34 may be the total length from the tip of the base shaft 30, but it is at least greater than 0 mm and in the range of up to 300 mm.

[0035] Next, the tip of the base shaft 30 having the coating portion 34 is welded to the surface of the inner layer 40 by laser. The wavelength of the laser used for welding is such that the material of the inner layer 40 or the coating portion 34, which is a resin that can be fused with the inner layer 40, is more easily absorbed than the material of the base shaft 30, and if both the inner layer 40 and the coating portion 34 are PTFE, the wavelength is absorbed by PTFE. The wavelength of the laser that PTFE absorbs is in the range from near-infrared to far-infrared, generally in the range of 0.7 μm to 20 μm, preferably 3 μm to 16 μm. As a laser that matches this wavelength range, for example, a CO2 laser can be used. The ease of absorption of the material referred to here may be expressed as the absorptivity, transmittance, or reflectance of the laser light.

[0036] When the inner layer 40 and coating portion 34 are irradiated with a laser, heating occurs from the surface of the irradiated object with longer wavelength lasers, and the process proceeds in the form of melting and welding.

[0037] By welding the coating portion 34 of the base shaft 30 to the outer surface of the inner layer 40, the coating portion 34 becomes an integrated protruding portion 44 with the inner layer 40, as shown in Figure 6. Next, a reinforcing layer 42 is braided to the outside of the inner layer 40. Then, an outer layer 41 is formed on the outside of the inner layer 40 and the reinforcing layer 42. First, a resin tube that will become the outer layer 41 is placed over the outside of the inner layer 40, the reinforcing layer 42 and the protruding portion 44, and heated to melt it. After this, the temperature of the tube is lowered and hardened to form the outer layer 41 that covers the inner layer 40 and the protruding portion 44. Once the outer layer 41 is formed, a circumferential portion of the base end of the tip tube 20 is cut off to form a semi-tube portion 24 (see Figure 3).

[0038] In this way, by coating the tip of the base shaft 30 with the same material as the inner layer 40 and integrating the tip of the base shaft 30 and the inner layer 40 by laser welding, the base shaft 30 can be firmly fixed to the inner layer 40.

[0039] As shown in Figure 7, the base shaft 30 may be joined to the inner layer 40 by the coating portion 34 being point-welded to the inner layer 40 at multiple locations using a laser.

[0040] The tip tube 20 to which the base shaft 30 is connected may have only an inner layer 40. In this case as well, the base shaft 30 having a coating portion 34 at its tip can be welded to the inner layer 40 by laser. The outer layer 41 may also be formed from the same material as the inner layer 40.

[0041] Alternatively, the coated portion 34 may be formed from the same material as the outer layer 41, and the base shaft 30 having the coated portion 34 at its tip may be laser-welded to the outer layer 41. In this case, the wavelength of the laser shall be such that it is not absorbed by the material of the base shaft 30 but is absorbed by the material forming the outer layer 41. Depending on the material of the outer layer 41, for example, a near- or mid-infrared laser or a far-infrared laser can be used.

[0042] As described above, the (1) medical device 10 according to this embodiment is a medical device 10 having a tip tube 20 and a base shaft 30 extending from the tip tube 20 toward the proximal end, wherein the tip tube 20 has an inner layer 40 facing an inner lumen 26 along the longitudinal axis, and the base shaft 30 has a tapered tip 32 at its tip, with its outer diameter tapering toward the tip, and is embedded in the inner layer 40. With the medical device 10 configured in this way, since the base shaft 30 is embedded in the inner layer 40, the connection strength between the tip tube 20 and the base shaft 30 can be increased. Furthermore, because the medical device 10 has a tapered tip 32 at the tip of the base shaft 30, and the tapered tip 32 is embedded in the inner layer 40, the tip tube 20 can not protrude toward the outer circumference at the connection portion with the base shaft 30, and the outer diameter of the tip tube 20 can be reduced to increase its passability in the body.

[0043] (2) In the medical device 10 described in (1) above, the medical device 10 may have an outer layer 41 on the outer circumference side of the inner layer 40 of the tip tube 20, and the inner layer 40 may have a protruding portion 44 that protrudes toward the outer layer 41, and the base shaft 30 may be embedded in the protruding portion 44. This makes it possible to embed the base shaft 30 on the outer circumference side of the inner layer 40 while ensuring the thickness between the base shaft 30 and the outer circumference surface of the outer layer 41, and to firmly connect the base shaft 30 to the tip tube 20 without increasing the outer diameter of the tip tube 20.

[0044] (3) In the medical device 10 described in (1) or (2) above, the inner layer 40 may be made of a fluororesin. This improves the sliding properties of the guide wire and other devices inserted into the lumen 26, while increasing the connection strength of the base shaft 30 to the tip tube 20.

[0045] The (4) method for manufacturing the medical device 10 according to this embodiment is a method for manufacturing a medical device 10 having a tip tube 20 and a base shaft 30 extending from the tip tube 20 toward the proximal end, and comprises the steps of: forming an inner layer 40 having a lumen 26 along the longitudinal axis; laser welding the tip of the base shaft 30, which is coated on the surface with the same material as the inner layer 40, to the surface of the inner layer 40; and forming an outer layer 41 on the outside of the inner layer 40. With this method for manufacturing the medical device 10, the base shaft 30 is connected to the tip tube 20 by embedding it in the inner layer 40, and the medical device 10 can be formed without increasing the outer diameter of the tip tube 20.

[0046] (5) In the method for manufacturing the medical device described in (4) above, the resin may be made of the same material as the inner layer 40. This ensures that the base shaft 30 and the inner layer 40 are reliably integrated.

[0047] (6) In the method for manufacturing the medical device 10 described in (4) or (5) above, in the step of laser welding, the wavelength of the laser used may be one that is absorbed by the material of the inner layer 40 but not absorbed by the material of the base shaft 30. This ensures that the base shaft 30 is securely embedded and fixed to the inner layer 40.

[0048] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made by those skilled in the art within the technical framework of the present invention. [Explanation of Symbols]

[0049] 10 Medical Devices 20 Tip tubes 20a tip 22 Tubular part 24 Half pipe section 26 lumen 30 Base shaft 32. Details 34 Coating section 40 Inner layer 41 Outer layer 42 Reinforcement layer 44 Protruding section

Claims

1. A medical device having a tip tube and a base shaft extending from the tip tube toward the proximal end, The aforementioned tip tube has an inner layer facing the lumen along the longitudinal direction, The base shaft is a medical device embedded in the inner layer, having a tapered tip that narrows towards the tip.

2. The aforementioned tip tube has an outer layer on the outer circumference side of the inner layer, The medical device according to claim 1, wherein the inner layer has a protruding portion that extends toward the outer layer, and the base shaft is embedded in the protruding portion.

3. The medical device according to claim 1 or 2, wherein the inner layer is formed of a fluororesin.

4. A method for manufacturing a medical device having a tip tube and a base shaft extending from the tip tube toward the proximal end, The steps include forming an inner layer having a lumen along the long axis, The steps include: laser welding the tip of the base shaft, which has a resin coated on its surface that can fuse with the inner layer, to the surface of the inner layer; The steps include forming an outer layer on the outside of the inner layer, A method for manufacturing a medical device having [a certain characteristic].

5. The method for manufacturing a medical device according to claim 4, wherein the resin is made of the same material as the inner layer.

6. The method for manufacturing a medical device according to claim 4 or 5, wherein in the step of laser welding, the wavelength of the laser used is such that the inner layer resin or the resin that can be fused with the inner layer is more easily absorbed than the material of the base shaft.

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