Expansion-controllable stent for balloon dilatation catheter

Abstract

An expansion controllable support for a balloon dilatation catheter comprises a support middle section, two ends and a fixed end, the two ends of the support middle section are connected with the fixed end respectively, the support middle section is of a telescopic structure, and the two ends of the support middle section are of a chain-shaped structure formed by connecting variable-diameter constraint rings. And the middle section of the bracket is axially connected with the fixed end through restraint rings from large to small in sequence. The two ends of the dilatation controllable stent are composed of the multi-stage variable-diameter restraint rings, the blood vessel damage is minimized while balloon dilatation is guaranteed, it can be guaranteed that the balloon recovers to the structural state before dilatation during pressure relief withdrawing, and the withdrawing performance of a balloon catheter is improved; the axial restraining rod is arranged in a penetrating mode, circumferential rotation or axial displacement of the balloon during expansion can be effectively prevented, and it is guaranteed that the balloon is accurately positioned in a blood vessel; when the balloon expands, the balloon protrusions protrude out of the grids, the pressure in the balloon is concentrated, the high-pressure expansion effect is achieved, stress is even, expansion is safer, and the expansion controllable support can control excessive expansion of the balloon.

Description

Technical Field

[0001] The present invention relates to medical balloon accessories, and particularly to an expandable controllable stent for a balloon dilation catheter, belonging to the technical field of vascular interventional therapy. Background Art

[0002] For cardiovascular diseases, balloon angioplasty is one of the most commonly used treatment methods. The balloon is generally in a long strip shape, with a large aspect ratio, and the material is mostly compliant or semi-compliant. The diameter and composition of the stenotic area of the artery are usually non-uniform, which also leads to non-uniform (axial and radial) expansion of the balloon. Especially when there are lesions in the vascular stenosis area (the lesions can be composed of a mixture of hard and soft plaque substances), it causes uneven stress during balloon dilation, resulting in the "dog-bone effect", causing further trauma to the blood vessel and damage to the blood vessels in the non-lesion area.

[0003] To avoid the occurrence of the above "dog-bone effect", a balloon catheter structure with a restraining stent has emerged. For example, a restraining stent for a balloon and a balloon catheter disclosed in the patent with the publication number CN218961564U. The restraining stent for a balloon and a balloon catheter include axially restraining rods arranged side by side in the circumferential direction and circumferentially restraining rings arranged at equal intervals in the axial direction. The circumferentially restraining rings include a plurality of zigzag restraining portions connected in the circumferential direction, and two adjacent zigzag restraining portions are fixedly connected to the axially restraining rod at the connection point. The axially restraining rod and the zigzag restraining portion enclose a grid window, and the zigzag restraining portion can be stretched and contracted through deformation. The axially restraining rod also includes a transition section and a fastening section connected to one end. This patent constrains the cone part of the balloon through the transition section and the fastening section on the axially restraining rod, and connects the restraining stent and the balloon catheter together to form a stable balloon catheter system with a restraining stent. However, the transition section on the axially restraining rod described in this patent is in a straight state, and the elastic deformation ability of a straight wire is much smaller than that of a bent wire. Moreover, it has also been found in actual use that for a balloon with a straight transition section in the restraining stent, after inflation, there is a situation where it cannot recover beyond the elastic deformation range. That is, after the balloon is inflated, the transition section of the restraining stent expands and deforms severely, resulting in difficulties in retraction and a risk of serious damage to the blood vessel wall. Therefore, it is necessary to conduct further research on it. Summary of the Invention

[0004] In order to solve the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide an expandable controllable stent for a balloon dilation catheter, and the specific technical solution is as follows: An expandable controllable stent for a balloon dilation catheter, comprising a middle section of the stent, two ends and a fixed end. The middle section of the stent is connected to the fixed end through the two ends respectively. The middle section of the stent is a telescopic structure, and the two ends are composed of a chain-like structure formed by variable-diameter restraint rings. The middle section of the stent is axially connected to the fixed end through restraint rings from large to small in sequence.

[0005] Furthermore, the restraint rings connected to the middle section of the stent in the chain-like structure are circumferentially spaced apart.

[0006] Furthermore, the restraint rings in the chain-like structure that are not connected to the middle section of the stent are circumferentially connected to form an annular structure.

[0007] Furthermore, the middle section of the stent is a telescopic grid structure composed of grid units. The grid units are composed of two parallel axial connecting lines and two parallel circumferential buffer lines connected to form a wavy quadrilateral structure. The wavy quadrilateral structure includes two axial wave peaks and one axial wave valley, and the axial wave valley is arranged between the two axial wave peaks.

[0008] Furthermore, the curve radian of the circumferential buffer line conforms to the curve radian of the sine function. The wire with the curve radian of the sine function has good ductility in the expanded state, and the spacing of the grid units and the grid size can also be designed with reference to the sine function. At the same time, it has good bending deformation ability, so as to realize stretching and contraction.

[0009] Furthermore, the grid units are axially misaligned and circumferentially aligned.

[0010] Furthermore, the axial connecting lines are axially spaced to form axial restraint bars.

[0011] Furthermore, the adjacent axial restraint bars in the middle section of the stent are axially misaligned and connected to the restraint rings at both ends through restraint ring connecting lines. The axial restraint bars include distal axial restraint bars and proximal axial restraint bars, and the distal axial restraint bars and proximal axial restraint bars are axially interspersed and arranged, and are respectively connected to the restraint rings at the distal end and the proximal end of the stent.

[0012] Furthermore, the restraint rings are elliptical.

[0013] Furthermore, the number of the chain-like structures corresponds to the number of the axial restraint bars.

[0014] Compared with the prior art, the advantages and effects of the present invention are as follows: both ends of the expandable controllable stent are composed of multi-stage variable-diameter elliptical restraint rings, which minimize blood vessel damage while ensuring balloon expansion, and can also ensure that the balloon returns to the pre-expansion structural state when the pressure is released and the balloon is withdrawn, enabling the balloon catheter system to have good withdrawal performance. Moreover, the axial restraint rods are arranged in an interspersed manner, and no force is applied to the same axial restraint rod when stretching both ends, which can effectively prevent the balloon from rotating circumferentially or displacing axially during expansion, ensuring its accurate positioning in the blood vessel; the expandable controllable stent can also follow the expansion or contraction of the balloon to control over-expansion of the balloon; when the balloon expands, the balloon protrusions protrude from the grid, concentrating the pressure inside the balloon to achieve the effect of high-pressure expansion, with uniform force and safer expansion; the present invention improves the compressive resistance and push-pull withdrawal performance of the balloon, enhances the adaptability to calcified lesions, and reduces the probability of over-expansion damaging blood vessels. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the overall state of the expandable controllable stent; Figure 2 Schematic diagram of the contracted state structure of the balloon equipped with the expandable controllable stent; Figure 3 Schematic diagram of the expanded state structure of the balloon equipped with the expandable controllable stent; Figure 4 Schematic diagram of the overall structure of the balloon expansion catheter equipped with the expandable controllable stent; Figure 5 Schematic diagram of the local structure at both ends; Figure 6 Schematic diagram of the axial restraint rod structure; Figure 7 Schematic diagram of the expanded state of the expandable controllable stent; In the figure: 1. Expandable controllable stent, 2. Middle section of the stent, 3. Proximal end of the stent, 4. Distal end of the stent, 5. Fixed end, 6. Axial connection line, 7. Distal axial restraint rod, 8. Circumferential buffer line, 9. Grid unit A, 10. Grid unit B, 11. Restraint ring C, 12. Restraint ring B, 13. Restraint ring A, 14. Restraint ring connection line, 15. Balloon, 16. Balloon protrusion, 17. Balloon groove, 18. Hollow part of the restraint ring, 19. Hollow part of the grid unit, 20. Catheter seat, 21. Catheter, 22. Chain structure, 23. Proximal axial restraint rod. EMBODIMENTS

[0016] The present invention will be further described below with reference to the accompanying drawings through specific embodiments: EXAMPLE

[0017] As Figures 1-7As shown in the figure, a stent with controllable expansion for a balloon dilation catheter includes a middle stent section 2, a proximal stent section 3, a distal stent section 4, and a fixed end 5. The middle stent section 2 is connected to the fixed end 5 through the proximal stent section 3 and the distal stent section 4 respectively. The proximal stent section 3 and the distal stent section 4 are chain-like structures 22 axially connected by a restraint ring C11, a restraint ring B12, a restraint ring A13, and restraint ring connection lines 14. The middle stent section 2 is a telescopic grid structure composed of grid units. A number of grid units are connected in circumferential alignment and axial dislocation. Each grid unit is composed of two parallel axial connection lines 6 and two parallel circumferential buffer lines 8 to form a wavy quadrilateral structure with the same length and width. The axial connection lines 6 of a number of grid units form axial restraint bars 7. The curve radian of the circumferential buffer lines 8 conforms to the curve radian of the sine function. Adjacent grid units have the same wavelength and wave height. During use, the telescopic of the middle stent section 2 can be achieved by controlling the deformation of the circumferential buffer lines 8, and it can also contract with the pressure relief of the balloon 15, facilitating the withdrawal operation. Embodiment

[0018] As Figures 1-4 shown in the figure, the stent with controllable expansion is formed by laser engraving a metal tube with a memory function or woven from a metal alloy wire with a memory function. In this embodiment, nitinol alloy is used because nitinol alloy itself has good elastic elongation (about 6% - 15%), which can allow it to withstand the deformation requirements applied by the balloon 15 to the middle stent section 2, and can allow the stent with controllable expansion to expand within the elastic deformation range. Embodiment

[0019] As Figure 3 shown in the figure, the fixed end 5 of the stent with controllable expansion is connected to the balloon 15. The balloon 15 is wrapped inside the middle stent section 2. The elasticity of the middle stent section 2 is lower than that of the balloon 15, so as to be able to limit the expansion of the balloon 15 and avoid excessive expansion of the balloon 15, thereby damaging the blood vessel.

[0020] The middle stent section 2 fits tightly with the balloon 15 and expands radially with the inflation of the balloon 15, and the length remains basically unchanged axially. A part of the surface of the balloon 15 protrudes from the hollow part 19 of the grid unit and the hollow part 18 near the restraint ring to form dot-like balloon protrusions 16 in contact with the inner wall of the blood vessel; another part of the surface of the balloon 15 is blocked by the solid part to form balloon grooves 17. The balloon grooves 17 are decompression grooves, which can make the pressure of each balloon protrusion 16 uniform and reduce the shear force existing during the expansion of the balloon 15.

[0021] The height difference between the balloon protrusion 16 and the balloon depression 17 is 0.15 mm - 0.40 mm. This height difference range ensures the area of the balloon protrusion 16 and also takes into account the force-bearing situation of the balloon 15. If the height difference of the balloon protrusion 16 is less than this range, the contact area between the balloon protrusion 16 and the blood vessel is small. When encountering a calcified lesion, it cannot ensure uniform action on the balloon 15. If the height difference of the balloon protrusion 16 is greater than this range, there is a risk that the metal stent is likely to cut through the balloon 15. Example

[0022] As Figure 4 As shown, a balloon dilation catheter equipped with an expandable controllable stent includes an expandable controllable stent 1, a catheter hub 20, a balloon 15, and a catheter 21. The proximal stent end 3 and the distal stent end 4 of the expandable controllable stent 1 can be connected to the fixed end 5 of the balloon 15 by means such as welding, heat melting, or bonding. The expandable controllable stent 1 sleeves the balloon 15 inside and clamps it tightly, and the proximal stent end 3 and the distal stent end 4 are in close fit with the tapered part of the balloon 15 to ensure effective retraction of the balloon 15 when it deflates. Example

[0023] As Figure 5 As shown, the proximal stent end 3 and the distal stent end 4 are a chain-like structure 22 axially connected by a restraint ring C11, a restraint ring B12, a restraint ring A13, and a restraint ring connection line 14. The restraint rings C11 are circumferentially spaced. The restraint ring C11 is larger than the restraint ring B12, and the restraint ring B12 is larger than the restraint ring A13. They are all elliptical because the opening is larger near the balloon end, so a larger restraint ring is needed for fitting. Moreover, the restraint rings B12 and A13 are connected to the circumferentially adjacent restraint rings to form an annular structure to adapt to the shape and size of the tapered part of the balloon 15 and also play a circumferential restraint role. Example

[0024] The middle section 2 of the stent can be adjusted according to the sine function law of the curve radian of the circumferential buffer line 8 in the grid unit according to balloons of different diameters to control its applicability. Variable-diameter restraint rings are used at the proximal stent end 3 and the distal stent end 4 to improve the situation of the chocolate balloon that when the connection between the proximal and distal ends is a straight line, the chocolate balloon is prone to deformation and cannot elastically retract when inflated and expanded, thereby controlling the passing outer diameter at the proximal and distal ends. Example

[0025] As Figure 3As shown, after the balloon 15 expands, under the radially outward expanding force of the balloon 15, the circumferential buffer line 8 of the grid unit changes from a wavy state to a nearly straight state to adapt to the size of the balloon 15 after expansion, and at the same time plays a role in controllable expansion. When the balloon 15 deflates and retracts, since the circumferential buffer line 8 is made of a memory function nickel-titanium alloy material after treatment, it can return to the initial state, making the grid unit change back to a wavy quadrilateral structure. Embodiment

[0026] As Figure 2 shown, the number of the chain-like structures 22 at both ends is determined by the axial constraint rods. The number of axial constraint rods in this embodiment is 6, that is, the number of the distal axial constraint rods 7 and the proximal axial constraint rods 23 is 3 each; if the diameter of the matched balloon 15 increases, in order to prevent the grid from being too sparse, the number of axial constraint rods will also increase. For example, if it increases to 7, the number of the chain-like structures 22 at both ends is 4 and 3 respectively. This is to prevent the area and height of the balloon bulge 15 from being too large, because when the area and height of the balloon bulge 15 are too large, the requirement for the bursting pressure of the balloon 15 will increase, and potential safety hazards are likely to occur; if the diameter of the matched balloon 15 decreases, to ensure that the stent distal end 4 and the stent proximal end 3 do not apply forces to the same axial constraint rod, and to prevent the balloon from undergoing circumferential rotation and axial displacement during expansion and stretching, and at the same time prevent the grid from being too dense, so the number of axial constraint rods is at least 3, and the number of the chain-like structures 22 at both ends is 2 and 1 respectively. This is to prevent the situation where the balloon bulge 16 cannot protrude from the grid, because if the balloon bulge 16 cannot protrude from the grid, the contact degree between the balloon 15 and the blood vessel is not good, and the expandable controllable stent made of metal material will directly contact the blood vessel, which is likely to damage the blood vessel. Embodiment

[0027] As Figure 7 shown, in the deployed state of the expandable controllable stent, when it is circumferentially rolled up, the upper edge and the lower edge of the middle section 2 of the stent coincide, the number of axial constraint rods is 3. The distal axial constraint rod 7 in the middle section 2 of the stent is connected to the chain-like structure 22 of the stent distal end 4, and the proximal axial constraint rod 23 adjacent to the distal axial constraint rod 7 is connected to the chain-like structure 22 of the stent proximal end 3. When the balloon 15 is inflated and expands, the chain-like structure 22 of the stent proximal end 3 will stretch the proximal axial constraint rod 23 and exert a force proximally, and the chain-like structure 22 of the stent distal end 4 will stretch the distal axial constraint rod 7 and exert a force distally. The stent proximal end 3 and the stent distal end 4 are interspersed and stretched to bear the force, so that the balloon 15 does not undergo circumferential rotation or axial displacement relative to the blood vessel wall when expanding or contracting. Embodiment

[0028] If the number of axial constraint rods is two, although it ensures that the proximal end 3 and the distal end 4 of the stent do not apply forces to the same axial constraint rod, circumferential rotation and axial displacement are likely to occur, posing a risk of damaging blood vessels.

[0029] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An expandable controllable stent for a balloon dilation catheter, comprising a middle section of the stent, two ends, and a fixed end. The middle section of the stent is connected to the fixed end through the two ends respectively, and is characterized in that, The middle section of the stent is a telescopic structure, and the two ends are composed of a chain-like structure (22) formed by connecting variable-diameter constraint rings. The middle section (2) of the stent is axially connected to the fixed end (5) through constraint rings that gradually decrease in size in sequence.

2. The expandable controllable stent for a balloon dilation catheter according to claim 1, wherein The constraint rings in the chain-like structure (22) that are connected to the middle section (2) of the stent are circumferentially spaced apart.

3. The expandable controllable stent for a balloon dilation catheter according to claim 1, characterized in that, The constraint rings in the chain-like structure (22) that are not connected to the middle section (2) of the stent are circumferentially connected to form an annular structure.

4. The expandable controllable stent for a balloon dilation catheter according to claim 1, wherein, The middle section (2) of the stent is a telescopic grid structure composed of grid units. The grid units are composed of two parallel axial connecting lines (6) and two parallel circumferential buffer lines (8) connected to form a wavy quadrilateral structure.

5. The expandable controllable stent for a balloon dilation catheter according to claim 4, wherein The curve radian of the circumferential buffer line (8) conforms to the curve radian of the sine function curve.

6. The expandable stent for a balloon dilation catheter according to claim 4, wherein The grid units are axially stagger-connected and circumferentially aligned-connected.

7. The expandable controllable stent for a balloon dilation catheter according to claim 4, wherein, The axial connecting lines (6) are axially spaced to form axial constraint rods.

8. The expandable controllable stent for a balloon dilation catheter according to claim 1, characterized in that, The adjacent axial constraint rods in the middle section (2) of the stent are axially stagger-connected to the constraint rings at both ends through constraint ring connecting lines (14). The axial constraint rods include distal axial constraint rods (7) and proximal axial constraint rods (23). The distal axial constraint rods (7) and proximal axial constraint rods (23) are axially interspersed and are respectively connected to the constraint rings of the distal end (4) and the proximal end (3) of the stent.

9. The expandable stent for a balloon dilation catheter according to claim 1, characterized in that, The constraint rings are elliptical.

10. The expandable stent for a balloon dilation catheter according to claim 1, wherein The number of the chain-like structures (22) corresponds to the number of the axial constraint rods.

Images