Delivery catheters and delivery systems

Abstract

To prevent kink at an end root part of an inner tube.SOLUTION: An inner shaft 10 of a delivery catheter 2 is movably inserted in an outer tube 20 in an axial direction. An outer periphery of a part 14 on the hand side in an inner tube 11 of the inner shaft 10 is covered with a coating tube 12 to extend an end part 13. An outer periphery of a part 13a nearer on an end side than the root part 13b of the end part 13 is provided with a stent 3. The end root part 13b near the coating tube 12 in the end part 13 is provided with a flexure concentration mitigation part 30. Flexure rigidity of the end root part 13b including the flexure concentration easing part 30 in the inner tube 11 is lower than flexure rigidity of the part 14 on the hand side and the coating tube 12 put together and higher than flexure rigidity of the part 13a on the end side and the stent 3 in the inner tube 11 put together.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a delivery catheter and a delivery system used for treating occluded or stenotic lesions, and particularly to a delivery catheter and a delivery system for delivering a stent to a lesion and implanting it in the opened lesion.

Background Art

[0002] The delivery catheter includes an outer tube and an inner tube inserted into the outer tube. The inner shaft includes an inner tube and a coating tube covering the inner tube. The tip portion of the inner tube extends out of the coating tube. A stent is provided on the outer periphery of the tip portion of the inner tube. The stent is held in a narrowed state, sandwiched between the inner peripheral surface of the outer tube and the outer peripheral surface of the inner tube. The stent and the delivery catheter constitute a delivery system. The delivery system is inserted into a lesion in a patient's body. Thereafter, when the outer tube is pulled toward the hand side with respect to the inner tube, the stent is released and implanted in the lesion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The stent, before release, is typically positioned on the tip side of the inner tube, near the cladding, and does not cover the cladding. Therefore, the tip side of the delivery system (where the tip side of the inner tube is located) is composed of the inner tube, stent, and outer tube; the cladding (where the tip base of the inner tube is located) is composed of the inner tube and outer tube; and the cladding section further proximal is composed of the inner tube, cladding, and outer tube. Consequently, in the delivery system, the cladding section is the most flexible and easily bent, while the cladding section is the least flexible and least likely to bend. When inserting such a delivery system to a lesion, if there are large bends in the internal pathway to the lesion, the cladding section is prone to concentrated bending deformation, potentially causing the inner tube to kink (buckle).

[0005] In view of these circumstances, the present invention aims to prevent kinking of the inner tube at the tip base of a delivery system including a delivery catheter and a stent by suppressing or mitigating concentrated bending deformation at the tip base. [Means for solving the problem]

[0006] To solve the aforementioned problems, the present invention provides a delivery catheter for delivering a stent to a lesion, It comprises an inner shaft and an outer tube through which the inner shaft is inserted so as to be movable in the axial direction, and the inner shaft is An inner tube on which the stent is provided on the outer circumference of the tip portion, A covering tube is provided so that the aforementioned tip portion extends outwards, and the covering tube covers the outer circumference of the portion of the inner tube closer to the handle than the aforementioned tip portion. A bending concentration relief portion is provided at the tip base portion near the coating tube at the tip portion, The tip portion is provided, and the portion of the tip portion that is closer to the tip than the tip base portion is the stent placement portion for the stent. The bending rigidity of the tip base portion of the inner tube, including the bending concentration relief portion, is lower than the combined bending rigidity of the near-hand portion of the inner tube and the covering tube, and higher than the combined bending rigidity of the tip portion of the inner tube and the stent. This makes it possible to ensure that the bending rigidity of the tip base where the bending concentration relief section is located in the delivery system before stent release is lower than the bending rigidity of the cladding tube section closer to the proximal end, and higher than the bending rigidity of the stent section closer to the tip.

[0007] Furthermore, the present invention relates to a delivery system comprising a stent and a delivery catheter for delivering the stent to a lesion, wherein the delivery catheter is It comprises an inner shaft and an outer tube through which the inner shaft is inserted so as to be movable in the axial direction, and the inner shaft is Inner tube and A covering tube is provided so that the tip portion of the inner tube extends outwards, and the covering tube covers the outer circumference of the portion of the inner tube closer to the handle than the tip portion. A bending concentration relief portion is provided at the tip base portion near the coating tube at the tip portion, The stent is provided on the outer circumference of the portion of the tip that is closer to the tip than the tip base portion, and is sandwiched between the tip portion and the outer tube. The bending rigidity of the tip base portion of the inner tube, including the bending concentration relief portion, is lower than the bending rigidity of the near end portion and the covering tube combined, and higher than the bending rigidity of the tip portion and the stent combined. The delivery system is characterized in that the bending rigidity of the tip base portion where the bending concentration relief portion is located is lower than the bending rigidity of the coating tube arrangement portion closer to the proximal end of the tip base portion, and higher than the bending rigidity of the stent arrangement portion closer to the tip of the tip base portion. In other words, in this delivery system, the bending rigidity gradually decreases, or in steps, from the proximal end to the tip end, in the order of the coated pipe section, the tip base section, and the stent section.

[0008] Preferably, the bending concentration relief portion is formed in an annular shape surrounding the outer circumference of the tip base portion, and the outer diameter of the bending concentration relief portion is larger than the outer diameter of the portions on both sides.

[0009] Preferably, the bending concentration relief portion includes an annular body separate from the inner tube, and the annular body is fitted around the outer circumference of the inner tube.

[0010] Preferably, the bending concentration relief portion includes an annular protrusion that is integral to the inner tube and rises outward in the radial direction of the tube. [Effects of the Invention]

[0011] According to the present invention, concentrated bending deformation at the tip base of the delivery system can be suppressed or mitigated, and kinking at the tip base of the inner tube can be prevented. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a side view showing a delivery system equipped with a delivery catheter according to the first embodiment of the present invention, with the stent released. [Figure 2] Figure 2(a) is a side cross-sectional view of the area near the tip of the delivery system in the state where the stent is housed before release. Figure 2(b) is a side cross-sectional view of the area near the tip of the delivery system in the process of releasing the stent. Figure 2(c) is a side cross-sectional view of the area near the tip of the delivery system in the state where the stent has been released. [Figure 3] Figure 3 is an enlarged side cross-sectional view of the circular part III in Figure 2(a). [Figure 4] Figure 4 is an explanatory side view showing the curved tip of the delivery system before the stent is released. [Figure 5] Figure 5 is an enlarged side cross-sectional view of the tip base portion and both sides thereof of a delivery catheter according to a second embodiment of the present invention. [Figure 6] FIG. 6 is an enlarged side cross-sectional view of the base portion at the tip of the delivery catheter according to the third embodiment of the present invention and both side portions thereof.

Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. <First Embodiment (FIGS. 1 to 4)> FIG. 1 shows a delivery system 1. The delivery system 1 is used for a treatment procedure for an occluded or stenosed lesion such as colorectal cancer, and includes a delivery catheter 2 and a stent 3. The stent 3 is delivered to the lesion by the delivery catheter 2 and released. The stent 3 is composed of a cylindrical wire mesh. In the following description, unless otherwise specified, the delivery system 1 is assumed to be in a state before the release of the stent 3.

[0014] As shown in FIG. 1, the delivery catheter 2 includes an inner hand operation portion 4, an outer hand operation portion 5, an inner shaft 10, and an outer tube 20. The inner hand operation portion 4 is inserted axially movably into the cylindrical outer hand operation portion 5. The inner shaft 10 extends from the tip of the inner hand operation portion 4, and the outer tube 20 extends from the tip of the outer hand operation portion 5.

[0015] As shown in Figures 1 and 2, the inner shaft 1 is inserted into the outer tube 20 so as to be movable in the axial direction. As shown in Figures 2(a) to 2(c), the inner shaft 10 comprises an inner tube 11 and a covering tube 12. The inner tube 11 is made of a resin such as PEEK. The outer diameter, inner diameter, and thickness of the inner tube 11 are constant along its entire length. The outer circumference of the portion 14 of the inner tube 11 closer to the tip (to the right in Figure 2(a)), excluding the tip portion 13, is covered by a resin covering tube 12. Hereinafter, the portion 14 of the inner tube 11 covered by the covering tube 12 will be referred to as the "covering tube portion 14". The tip portion 13 of the inner tube 11 extends from the covering tube 12. As shown in Figure 2(a), a conical tip piece 17 is provided at the tip of the inner tube 10.

[0016] As shown in Figure 2(a), a stent 3 is provided on the outer circumference of the tip portion 13 of the inner tube 11 before release. The outer tube 20 covers the outer circumference of the stent 3. The stent 3 is held in place by being sandwiched between the tip portion 13 of the inner tube 11 and the outer tube 20. As shown in Figure 2(b), annular resistance portions 15 are provided on the outer circumference of one or more predetermined locations on the tip portion 13 of the inner tube 11 to increase frictional resistance with the stent 3 during release operations, etc.

[0017] As shown in Figure 2(a), the proximal end of stent 3 before release (right end in Figure 2(a)) does not reach the cladding tube 12. In other words, stent 3 is not placed over the tip base portion 13b of the inner tube 11 near the cladding tube 12. Stent 3 is placed only over the tip portion 13a of the inner tube 11 that is further forward than the tip base portion 13b (left side in Figure 2(a)). The tip portion 13a is the stent placement area for stent 3.

[0018] As shown in Figure 3, the tip base portion 13b of the inner tube 13 is provided with an annular body 30 (bending concentration relief portion) surrounding its outer circumference. The annular body 30 is an annular member separate from the inner tube 11 and is fitted onto the outer circumference of the inner tube 11. The inner surface of the annular body 30 is bonded to the outer surface of the inner tube 11 via adhesive 16. The material of the annular body 30 is not particularly limited and may be resin or metal. Preferably, the annular body 30 is flexible or elastic.

[0019] The proximal end 30e of the annular body 30 is positioned to abut against or be close to the tip of the cladding tube 12. Although not shown in the illustration, an annular cap may be provided at the tip of the cladding tube 12, and the proximal end of the annular body 30 may be positioned to abut against or be close to the annular cap.

[0020] The outer diameter of the annular body 30 is larger than the outer diameters of the two axial portions 13a and 14 of the inner tube 13, which surround the annular body 30. Furthermore, the outer diameter of the annular body 30 is smaller than the outer diameter of the cladding tube 12. The tube thickness of the annular body 30 is smaller than the difference between the outer radius of the cladding tube 12 and the outer radius of the inner tube 11. As shown in Figure 2(a), the axial length L of the annular body 30 (bending concentration relief section) is... 30 Preferably L 30 =Approximately 1mm to 4mm. Total length L of the tip portion 13 of the inner tube 13 (the portion from the near end of the tip piece 17 to the tip of the covering tube 2) 13 The axial length L of the annular body 30 (bending concentration relief section) relative to the annular body 30. 30 The ratio is preferably (L 30 / L 13 ) = approximately 0.005 to 0.04.

[0021] The annular body 30 functions as a bending concentration relief section that mitigates the concentration of bending deformation at the tip base 13b. The bending stiffness of the tip base 13b of the inner tube 11, including the annular body 30 (bending concentration relief section), is lower than the combined bending stiffness of the inner tube 11's inner coating portion 14 (the portion closer to the handle) and the coating 12, but higher than the combined bending stiffness of the tip portion 13a of the inner tube 11 and the stent 3. Furthermore, the bending stiffness of the tip base 13b of the inner tube 11, including the annular body 30 (bending concentration relief section), is higher than the bending stiffness of the portions 13a and 14 on both sides of the annular body 30 in the axial direction of the inner tube 11.

[0022] As shown in Figure 3, the proximal end of the stent 3 before release is positioned to be close to or in contact with the tip 30f of the annular body 30. Therefore, as shown in Figure 2(a), the tip side portion 1a of the delivery system 1 (the arrangement of the tip portion 13a of the inner tube 11 and thus the arrangement of the stent 3) is mainly composed of the inner tube 11, the stent 3, and the outer tube 20. The tip base portion 1b of the delivery system 1 (the arrangement of the tip base portion 13b of the inner tube 11) is mainly composed of the inner tube 11, the outer tube 20, and the annular body 30. The cladding tube arrangement portion 1c on the proximal side of the tip base portion 1b of the delivery system 1 is mainly composed of the inner tube 11, the cladding tube 12, and the outer tube 20.

[0023] The bending stiffness of the tip base 1b in the delivery system 1 is lower than that of the cladding tube arrangement section 1c closer to the proximal end, and higher than that of the stent arrangement section 1a closer to the tip. The bending stiffness of the delivery system 1 decreases gradually or in steps from the proximal end to the tip, in the order of cladding tube arrangement section 1c, tip base 1b, and stent arrangement section 1a.

[0024] In the delivery system 1, the annular body 30 can reinforce the bending rigidity (resistance to bending) of the tip base 1b. In other words, it is possible to prevent the bending rigidity of the delivery system 1 from decreasing discontinuously at the tip base 1b. To put it another way, it is possible to prevent the flexibility of the delivery system 1 from increasing discontinuously at the tip base 1b.

[0025] Delivery system 1 is used for treating obstructed or narrowed lesions in the following manner. As shown in Figure 2(a), the delivery system 1 is inserted toward the lesion with the stent 3 housed in its tip side portion 1b. As shown in Figure 4, if there is a large bend in the internal pathway to the lesion, the delivery system 1 is curved to match the bend. At this time, the annular body 30 prevents the bending from concentrating at the tip base portion 1b. This allows the delivery catheter to be curved with a nearly uniform curvature from the stent placement portion 1a to the cladding tube placement portion 1c. As a result, kinking (bending buckling) of the tip base portion 13b of the inner tube 11 can be prevented.

[0026] After inserting the tip of the delivery system 1 to the lesion, the outer proximal control section 5 is pulled towards the proximal end relative to the inner proximal control section 4. As a result, the outer tube 5 is pulled towards the proximal end relative to the inner shaft 4, as shown in Figures 2(b) to 2(c). This releases the stent 3 from the delivery catheter 2, causing it to elastically expand and open the lesion. The expanded stent 3 remains in place at the lesion, maintaining the open state of the lesion.

[0027] Next, other embodiments of the present invention will be described. In the following embodiments, components that overlap with those described above are denoted by the same reference numerals in the drawings and their descriptions are omitted. <Second Embodiment (Figure 5)> As shown in Figure 5, in the second embodiment, an annular protrusion 32 is formed at the tip base portion 13b of the inner tube 11. The protrusion 32 is integral with the inner tube 11 and protrudes outward in the radial direction of the tube. The outer diameter of the protrusion 32 is larger than the outer diameter of the portions 13a and 14 on both sides of the inner tube 11 in the axial direction of the tube. The proximal end 32e of the protrusion 32 is in contact with or close to the tip of the cladding tube 12. The proximal end of the stent 3 before release is close to or in contact with the tip 32f of the protrusion 32.

[0028] The raised portion 32 constitutes a bending concentration mitigation section. The raised portion 32 reinforces the bending rigidity (resistance to bending) of the tip base portion 1b, preventing the tip base portion 13b of the inner tube 11 from kinking (bending buckling).

[0029] <Third Embodiment (Figure 5)> As shown in Figure 5, in the third embodiment, the bending concentration relief portion 33 is provided so as to span the tip base portion 13b of the inner tube 11 and the inner portion 14 of the coating tube. The tip side tube portion 12a of the coating tube 12 covers the outer circumference of the near side portion 33b of the bending concentration relief portion 33. The tip side portion 33a of the bending concentration relief portion 33 extends toward the tip of the coating tube 12. The bending concentration relief portion 33 may be composed of an annular body separate from the inner tube 11, or it may be composed of a raised portion that is the same as the inner tube 11. The tip side tube portion 12a of the coating tube 23 may be thinner than the tube portion 12b closer to the tip by the thickness of the bending concentration relief portion 33.

[0030] The present invention is not limited to the embodiments described above, and various modifications can be made without departing from its spirit. For example, the bending concentration relief portion may be an embedded member embedded in the tip base portion 13b of the inner pipe 11. The bending rigidity of the bending concentration relief section may decrease continuously or stepwise from the near end to the far end of the bending concentration relief section. The bending concentration relief section may be the same as the coating pipe 12, and its outer diameter may be smaller than the outer diameter of the coating pipe 12. The bending concentration relief portion may include both the annular body 30 and the raised portion 33. A gap of a small size (e.g., a few millimeters or less) may be formed between the end face of the bending concentration relief section and the tip face of the cladding tube, so as not to cause kinking. A cylindrical spacer may be provided between the inner surface of the tip portion of the cladding tube and the outer surface of the inner tube to align the cladding tube and the inner tube. Preferably, the spacer is made of a soft resin and has little effect on the bending rigidity of the delivery catheter. [Industrial applicability]

[0031] This invention can be applied, for example, to a treatment device for a blocked or narrowed lesion. [Explanation of symbols]

[0032] 1. Delivery System 1a Tip side (stent placement area) 1b Tip base (the tip base of the inner tube and the location of the bending concentration relief section) 1c Cladding tube placement section 2. Delivery Catheter 3 stents 4. Inner control panel 5 Outside hand control section 10 Inner Shaft 11 Inner tube 12 Cladding tube 12a End portion of the cladding pipe 12b The tube section near the handle 13. Tip of the inner tube 13a Tip portion (stent placement area) 13b Tip base 14. Inner part of the coated pipe (the part closest to the user) 20 Outer Tube 30. Ring-shaped body (bending concentration relief section) 30e Ring-shaped end 30f Tip of the ring-shaped body 32. Raised section (bending concentration relief section) 32e Protruding end of the raised section 32f Tip of the raised section 33 Bending concentration relief section 33a Tip side part 33b Hand side

Claims

1. A delivery catheter that delivers a stent to the lesion site, It comprises an inner shaft and an outer tube through which the inner shaft is inserted so as to be movable in the axial direction, and the inner shaft is An inner tube on which the stent is provided on the outer circumference of the tip portion, A covering tube is provided so that the aforementioned tip portion extends outwards, and the covering tube covers the outer circumference of the portion of the inner tube closer to the handle than the aforementioned tip portion. A bending concentration relief portion is provided at the tip base portion near the coating tube at the tip portion, The tip portion is provided, and the portion of the tip portion that is closer to the tip than the tip base portion is the stent placement portion for the stent. A delivery catheter characterized in that the bending rigidity of the tip base portion of the inner tube, including the bending concentration relief portion, is lower than the combined bending rigidity of the proximal portion of the inner tube and the covering tube, and higher than the combined bending rigidity of the tip portion of the inner tube and the stent, the bending concentration relief portion is formed in an annular shape surrounding the outer circumference of the tip base portion, and the outer diameter of the bending concentration relief portion is larger than the outer diameter of the portions on both sides of the inner tube in the axial direction on either side of the bending concentration relief portion, and smaller than the outer diameter of the covering tube.

2. The delivery catheter according to Claim 1, characterized in that the axial length of the bending concentration relief portion is 1 mm to 4 mm, or the ratio of the axial length of the tip base portion to the total length of the tip portion is 0.005 or more and 0.04 or less.

3. The delivery catheter according to claim 1 or 2, characterized in that the bending concentration relief portion includes an annular body separate from the inner tube, and the annular body is fitted around the outer circumference of the inner tube.

4. The delivery catheter according to claim 1 or 2, characterized in that the bending concentration relief portion includes an annular protrusion that is identical to the inner tube and protrudes outward in the radial direction of the tube.

5. A delivery system comprising a stent and a delivery catheter for delivering the stent to a lesion, wherein the delivery catheter is It comprises an inner shaft and an outer tube through which the inner shaft is inserted so as to be movable in the axial direction, and the inner shaft is Inner tube and A covering tube is provided so that the tip portion of the inner tube extends outwards, and the covering tube covers the outer circumference of the portion of the inner tube closer to the handle than the tip portion. A bending concentration relief portion is provided at the tip base portion near the coating tube at the tip portion, The stent is provided on the outer circumference of the portion of the tip that is closer to the tip than the tip base portion, and is sandwiched between the tip portion and the outer tube. The bending rigidity of the tip base portion of the inner tube, including the bending concentration relief portion, is lower than the combined bending rigidity of the near end portion and the coating tube, and higher than the combined bending rigidity of the tip portion and the stent, the bending concentration relief portion is formed in an annular shape surrounding the outer circumference of the tip base portion, and the outer diameter of the bending concentration relief portion is larger than the outer diameter of the portions on both sides of the inner tube in the axial direction of the tube, and smaller than the outer diameter of the coating tube. A delivery system characterized in that the bending rigidity of the tip base portion where the bending concentration relief portion is located is lower than the bending rigidity of the coating tube arrangement portion closer to the proximal end of the tip base portion, and higher than the bending rigidity of the stent arrangement portion closer to the tip of the tip base portion.

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