Constraining stent and balloon catheter having constraining stent

Abstract

Provided in the present application are a constraining stent and a balloon catheter having the constraining stent, which are used for constraining a balloon on an outer side of the balloon. The constraining stent comprises a mesh main body and at least one microneedle carrying a drug on its surface. The mesh main body is provided with a plurality of mesh openings, and a fixed end of the microneedle is fixed to the mesh main body. When the balloon is inflated and expanded, a portion of a balloon body of the balloon protrudes outward through the mesh openings to form pillow portions, and the pillow portions can push up a free end of the microneedle into a raised state. According to the present application, the microneedle is disposed on the constraining stent, so that the microneedle can be pushed out into a raised state as the balloon expands, and thus the microneedle can scratch and pierce diseased tissue during the pushing-out process, allowing the drug to better enter the diseased tissue.

Description

Constraint stents and balloon catheters with constraint stents Cross-reference to related applications

[0001] This application claims priority to Chinese application No. 202510398298.4, filed on March 28, 2025, the full text of which is incorporated herein by reference. Technical Field

[0002] This application relates to the field of medical devices, and in particular to a restraint stent and a balloon catheter having a restraint stent. Background Technology

[0003] For cardiovascular diseases, balloon angioplasty is one of the most commonly used treatments. Traditional balloon angioplasty is often accompanied by vascular damage. For example, during balloon dilation, the diameter of the proximal and distal ends of the balloon is larger than that of the middle part, a phenomenon known as the "dog bone effect." This leads to excessive dilation of the vessels contacted by the balloon ends, causing damage to the vessel wall and accelerating vascular dissection due to longitudinal elongation of the balloon. It can also cause acute vascular occlusion at the lesion site and postoperative restenosis. For newer drug-eluting balloon catheters, the surface of the balloon carries anti-proliferative drugs and a restraining stent. Although the anti-proliferative drugs on the balloon surface can be transferred upon contact with plaques within the blood vessel, the drugs usually only act on the outer surface of the plaque, and the anti-proliferative effect is extremely limited, especially for some old plaques, where the range and effectiveness of drug efficacy are significantly limited. Summary of the Invention

[0004] In view of this, this application provides a restraint stent equipped with microneedles for drug delivery. When the restraint stent expands with the balloon, the microneedles can make deeper contact with the lesion tissue, thereby transferring the drug to a deeper location in the lesion tissue.

[0005] The first aspect of this application provides a restraint bracket for restraining a balloon outside the balloon. The restraint bracket includes a mesh body and at least one microneedle with a drug-loaded surface. The mesh body has a plurality of mesh openings. The fixed ends of the microneedles are fixed to the mesh body. When the balloon inflates and expands, a portion of the balloon protrudes from the mesh openings to form a occipital portion. The occipital portion can lift the free ends of the microneedles to an upturned state.

[0006] Furthermore, before the balloon expands and unfolds, the extension direction of the microneedles is parallel to the direction from the proximal end to the distal end of the mesh body.

[0007] Furthermore, the free end of the microneedle points towards the distal end of the mesh body.

[0008] Furthermore, before the balloon expands and unfolds, the free ends of the microneedles do not extend beyond the outer periphery of the mesh body.

[0009] Furthermore, along the direction from the free end to the fixed end, the microneedle sequentially includes a needle tip, a needle body, and a needle base, wherein the width of the needle base is greater than the width of the needle body, and the width of the needle body is greater than the width of the needle tip.

[0010] Furthermore, before the balloon expands and deploys, the mesh body is in a flat state, the mesh is rhomboid, and the fixed end is fixed to one interior angle of the rhomboid, the angle δ of the interior angle satisfies: 15°≤δ≤30°;

[0011] After the balloon expands and unfolds, the flat unfolded area S of the mesh satisfies: 4mm2≤S≤10mm2.

[0012] Furthermore, the length L of the microneedle satisfies: 1.5mm≤L≤3mm.

[0013] Furthermore, the outer surface of the mesh body is loaded with a drug, and / or the outer surface of the balloon is loaded with a drug.

[0014] Furthermore, when the balloon expands, a concave groove is formed between two adjacent occipital regions on the balloon body, and the height difference h between the highest point of the occipital region and the lowest point of the groove satisfies: 0.2mm≤h≤0.6mm.

[0015] A second aspect of this application provides a balloon catheter, including a balloon and the aforementioned restraint stent.

[0016] The technical solutions provided by the embodiments of this application may include the following beneficial effects:

[0017] This application involves placing drug-loaded microneedles on a restraint stent. When the restraint stent expands with the balloon, the balloon bulges out through the mesh to form a occipital region. This occipital region can lift the drug-loaded microneedles to an upturned state. During the process of the microneedles being upturned and in their final upturned state, the microneedles can make deeper contact with the lesions in the blood vessels and even partially penetrate the lesions. This allows the drugs loaded on the microneedles to be transferred to deeper locations in the lesions, thereby enhancing their efficacy. Attached Figure Description

[0018] Figure 1 is a schematic diagram of the structure of the balloon catheter of this application after it expands and deploys in vivo;

[0019] Figure 2 is a structural schematic diagram of a balloon embodiment of this application;

[0020] Figure 3 is a partial flat view of the constraint bracket in the contracted state according to an embodiment of this application;

[0021] Figure 4 is a magnified view of part A in Figure 3;

[0022] Figure 5 is a magnified view of part B in Figure 1;

[0023] Figure 6 is a schematic diagram of the microneedle rotation angle range;

[0024] Figure 7 is a schematic diagram of the structure of a microneedle according to an embodiment of this application;

[0025] Figure 8a is a flat view of the mesh body of an embodiment of this application when it is contracted;

[0026] Figure 8b is a tiling view of the mesh structure in Figure 8a as it expands.

[0027] Explanation of reference numerals in the attached figures:

[0028] 100. Constraint support; 11. Mesh body; 12. Connecting part; 13. Fixing part; 111. Mesh; 112. Microneedle; 1121. Free end; 1122. Fixing end; 1123. Needle tip; 1124. Needle body; 1125. Needle seat; 200. Balloon; 21. Balloon body; 211. Occipital region; 212. Groove; 22. Shoulder region; 23. Tube foot. Detailed Implementation

[0029] The specific embodiments of this application are described in detail below with reference to the accompanying drawings.

[0030] In the description of this application, the proximal and distal ends are defined with reference to the position of the operator when the device can be seen or not seen during use. That is, the distal end refers to the end of the device or component that is relatively far away from the operator, while the proximal end refers to the end of the device or component that is relatively close to the operator.

[0031] As shown in Figure 1, this application discloses a balloon catheter, which includes a balloon 200 and a constraint bracket 100 disposed on the outer periphery of the balloon 200. The constraint bracket 100 is used to constrain the radial deformation of the balloon 200.

[0032] Figure 2 shows a schematic diagram of the balloon 200. The balloon 200 includes a central balloon body 21, and shoulder sections 22 and tube ends 23 located on both sides of the balloon body 21. One end of each shoulder section 22 is fixedly connected to both ends of the balloon body 21, and the other end of the shoulder section 22 is connected to the tube end 23. When inflated, the shoulder section 22 is approximately conical, with the side with the larger cross-sectional area connected to the balloon body 21 and the side with the smaller cross-sectional area connected to the tube end 23.

[0033] The structure of the restraint bracket 100 is shown in Figure 3. The restraint bracket 100 includes a mesh body 11, a connecting portion 12, and a fixing portion 13. Both sides of the mesh body 11 are connected to one end of the connecting portion 12, and the other end of the connecting portion 12 is connected to the fixing portion 13. The connecting portion 12 includes multiple connecting wires, one end of which is connected to the mesh body 11, and the other end is connected to the trough of the fixing portion 13. The fixing portion 13 adopts a sinusoidal curve shape, with a height difference between the crest and trough of 2mm to 4mm. The sinusoidal curve shape allows the restraint bracket 100 to expand appropriately when assembled with the balloon 200, facilitating the passage of the balloon 200 through the restraint bracket 100. Simultaneously, selecting a height difference of 2mm to 4mm between the crest and trough increases the contact area between the fixing portion 13 and both ends of the balloon 200, improving the connection strength between the two.

[0034] When the aforementioned restraint bracket 100 is fitted onto the outside of the balloon 200, the fixing portions 13 at both ends of the restraint bracket 100 are fixed to the tube feet 23 at both ends of the balloon 200, respectively, to fix the mutual fixation between the restraint bracket 100 and the balloon 200 and prevent the balloon 200 from shifting. The fixing portions 13 can be fixed to the tube feet 23 at both ends of the balloon 200 by hot air welding, glue bonding, or laser welding.

[0035] As shown in Figures 1 and 5, the balloon 200 is initially in a contracted state. When an inflation medium is introduced into the balloon 200, it gradually inflates. As the balloon 200 inflates, the constraint support 100 fitted over the outside of the balloon 200 also expands. When the balloon 200 inflates to a certain extent, under the combined action of internal pressure and the constraint of the constraint support 100, a portion of the balloon 200 bulges out of the mesh 111 of the mesh body 11. The bulging balloon 200 forms a posterior portion 211 protruding from the mesh body 11, and concave grooves 212 are formed between adjacent posterior portions 211. When the balloon 200 inflates to a predefined maximum extent, the state of the constraint support 100 is defined as the expanded state.

[0036] As shown in Figure 4, which is a magnified view of point A in Figure 3, the fixed end 1122 of the microneedle 112 is fixed to the mesh body 11 corresponding to the edge of the mesh 111. As the balloon 200 expands or contracts, the microneedle 112 can rotate within a certain angle range. When the balloon 200 expands, the microneedle 112 is lifted by the occipital portion 211, causing the free end 1121 to be lifted into an upturned state. During this lifting process, the microneedle 112 can puncture and penetrate the lesion tissue within the groove 212.

[0037] The microneedle 112 is coated or impregnated with a drug, such as an anti-intima hyperplasia drug, like rapamycin, paclitaxel, or its derivatives. When the microneedle 112 punctures the lesion tissue, the drug carried on its surface can penetrate deeper into the lesion. Compared to cutting balloons, the microneedle 112 in this application is gradually pushed and flipped to an upturned state by the occipital portion 211 of the bulging mesh 111 on the balloon 200. The microneedle 112 does not simply puncture the lesion tissue within the blood vessel; simultaneously, during the entire movement of the microneedle 112, the drug carried on its surface can be transferred to the punctured and inserted sites. Compared to some balloon-based drug delivery methods, the microneedle 112 in this application can transfer anti-intima hyperplasia drugs such as rapamycin to relatively deeper locations within the lesion tissue, resulting in a more significant drug delivery effect and lower dosage.

[0038] In some embodiments, the surfaces of the balloon 200 and the mesh body 11 may also be loaded with anti-endometrial hyperplasia drugs. As previously shown, during the rotation of the microneedle 112, it may cause a certain degree of abrasion to the lesion tissue. At this time, the drugs loaded on the surfaces of the balloon 200 and the mesh body 11 can also be transferred to the abraded lesion tissue and the surface of the lesion tissue. In this way, by loading drugs onto the surfaces of the microneedle 112, balloon 200, and mesh body 11 around the location of the microneedle 112, different depths of the lesion tissue can be in contact with the drug, resulting in better drug delivery.

[0039] The wall thickness of an artery is generally 1mm to 2mm. If severe calcification occurs in an artery, the thickness of the artery wall will increase significantly. At this time, the wall thickness is equal to the original normal wall thickness plus the thickness of the calcified layer, which is generally greater than 3mm. In order for the microneedle 112 to penetrate deeper into the vascular tissue without puncturing the vessel wall, the length L of the microneedle 112 is controlled to satisfy: 1.5mm ≤ L ≤ 3mm.

[0040] As shown in Figure 7, in some embodiments, the microneedle 112 sequentially includes a needle tip 1123, a needle body 1124, and a needle base 1125 along the direction from the free end 1121 to the fixed end 1122. The included angle β formed by the two sides of the needle tip 1123 satisfies: 8°≤β≤15°, and the length L1 of the needle tip 1123 satisfies: 0.5mm≤L1≤1mm. This configuration not only gives the needle tip 1123 better strength, but also allows the tip of the needle tip 1123 to better penetrate diseased tissue, especially calcified diseased tissue.

[0041] The included angle γ formed by the two sides of the needle body 1124 satisfies: 2°≤γ≤5°, and the length L2 of the needle body 1124 satisfies: 1mm≤L2≤2mm. This design ensures that the needle body 1124, as the main drug carrier, not only has a large drug-carrying area but also a smooth transition design with the needle tip 1123. The needle body 1124 can smoothly penetrate into the diseased tissue along with the needle tip 1123, injecting the carried drug into the diseased tissue. When the balloon 200 is depressurized, the needle body 1124 can also be quickly withdrawn from the diseased tissue and return to its original shape. One end of the needle body 1124 is connected to the needle tip 1123, and the other end is connected to one end of the needle hub 1125. The other end of the needle hub 1125 is connected to the mesh body 11. The width of the needle hub 1125 is greater than the width of the needle body 1124, and the width of the needle body 1124 is greater than the width of the needle tip 1123. The width design of the needle tip 1123, needle body 1124 and needle base 1125 makes the intensity distribution of the microneedle 112 more uniform and the connection with the mesh body 11 more secure.

[0042] Before the balloon 200 expands, the microneedle 112 is in a contained state. At this time, the free end 1121 of the microneedle 112 does not extend beyond the outer periphery of the mesh body 11, where the outer periphery is the outer contour surface of the mesh body 11. Because the free end 1121 of the microneedle 112 does not extend beyond the outer periphery of the mesh body 11, the microneedle 112 is less likely to puncture or damage non-disease vascular tissue during the insertion of the balloon catheter into the blood vessel, and the insertion process is easier to operate.

[0043] In some embodiments, before the balloon 200 inflates, the extension direction of the microneedles 112 is parallel to the proximal-to-distal direction of the mesh body 11. In the description of this application, unless otherwise specified, "parallel" means substantially parallel, not strictly geometrically parallel, and an angle is allowed between them. Therefore, the extension direction of the microneedles 112 being parallel to the proximal-to-distal direction of the mesh body 11 means that the extension direction of the microneedles 112 is substantially parallel to the length direction of the mesh body 11. The reason for this arrangement is that when the length direction of the microneedles 112 is the same as the axial direction of the mesh body 11, the microneedles 112 can have a certain length, facilitating deeper insertion into the lesion tissue without increasing the radial dimension of the mesh body 11.

[0044] When the extension direction of the microneedles 112 is parallel to the proximal-to-distal direction of the mesh body 11, regardless of whether the free end 1121 of the microneedles 112 points to the distal or proximal end of the mesh body 11, the free end 1121 of the microneedles 112 will never exceed the outer periphery of the mesh body 11 before the balloon 200 first inflates and deploys. However, once the balloon 200 needs to retract after inflating, that is, after the balloon 200 changes from an inflated state to a contracted state, the microneedles 112 may not be able to fully rebound to their initial state due to excessive deformation, and the free end 1121 of the microneedles 112 may protrude from the outer periphery of the mesh body 11. Thus, when the restraint balloon is withdrawn from the body, it may be affected by the slightly protruding microneedles 112. To avoid this situation, the free end 1121 of the microneedles 112 can be positioned to point towards the distal end of the mesh body 11.

[0045] Figure 6 shows the angular relationship between the microneedle 112 and the axial direction of the mesh body 11 in the concealed and raised states. The free end 1121 of the microneedle 112 can rotate around the fixed end 1122. In the concealed state, the angle α1 between the microneedle 112 and the axial direction of the mesh body 11 satisfies: 0°≤α1≤5°, ensuring that the microneedle 112 is essentially within the outer periphery of the mesh body 11. The free end 1121 can also be slightly retracted, forming a small angle α1. This effectively controls the radial dimension of the constraint stent 100 from increasing due to the presence of the microneedle 112, facilitating the insertion and withdrawal of the balloon catheter. In the raised state, the angle α2 between the microneedle 112 and the axial direction of the mesh body 11 satisfies: 60°≤α2≤90°. In this state, the microneedle 112 can puncture a longer distance and penetrate deeper, better delivering the drug to the deeper lesions within the blood vessels, resulting in better drug delivery efficacy.

[0046] When the balloon 200 inflates, a height difference h exists between the highest point of the occipital portion 211 and the lowest point of the groove portion 212. This height difference h affects the tilt angle of the microneedle 112. A larger height difference h results in a more pronounced uneven structure on the surface of the balloon 200 (i.e., the occipital portion 211 and the groove portion 212), a larger tilt angle of the microneedle 112, and a larger puncture range, which is more conducive to drug delivery. However, for the balloon 200, a larger height difference h is not always better. If the height difference h is too large, it will not only fail to effectively increase the tilt angle of the microneedle 112, but may also easily lead to the rupture of the balloon 200 due to excessive pressure and the entry of diseased tissue into the groove portion 212. Therefore, to ensure that the balloon catheter effectively compresses the calcified vessel wall and that the drug-carrying microneedle 112 can effectively puncture the vascular tissue in the groove portion 212, the height difference h must be controlled to meet the following condition: 0.2 mm ≤ h ≤ 0.6 mm.

[0047] In some embodiments, the mesh 111 is rhomboid in shape, with the long diagonal parallel to the axial direction of the mesh body 11. This arrangement allows the mesh body 11 to have a relatively small outer contour before the balloon 200 inflates, facilitating a reduction in the circumferential size of the constraint support 100. After the balloon 200 inflates, the rhomboid mesh deforms, with the short diagonal lengthening and the long diagonal shortening, until the mesh 111 reaches a stable state.

[0048] Referring to Figures 8a and 8b, which show the same mesh body in both contracted and expanded states, the mesh body 11 contains n columns of mesh, with each column having m, m-1, m, m-1… mesh openings 111 (m = 10) distributed sequentially from the near end to the far end. Although only m-1 openings are shown in the even-numbered columns in the figures, the mesh body 11 in the curled state also has m openings. This is because in the flat state, one opening in the even-numbered column is separated and not displayed. If the mesh body 11 in the figures is curled, a and a', b and b' will overlap, forming another mesh opening 111. Therefore, in the curled state, the number of openings contained in each circumference of the mesh body 11 is the same, and n×m mesh openings 111 will be formed on the surface of the mesh body 11.

[0049] The fixed end 1122 of the microneedle 112 is fixed at the inner corner of the rhomboid mesh. To facilitate the insertion of the balloon catheter, the fixed end 1122 of the microneedle 112 is fixed at the inner corner of the long diagonal of the rhomboid mesh, and the free end 1121 of the microneedle 112 faces the distal end of the mesh body 11. In some embodiments, each mesh 111 is provided with a corresponding microneedle 112.

[0050] As shown in Figure 2, in some embodiments, the included angle δ of the interior angles corresponding to the long diagonal of the rhomboid mesh satisfies: 15°≤δ≤30°. When the interior angle satisfies the above relationship, the mesh 111 of the constraint stent 100 can be kept to its maximum contraction state, minimizing the overall outline size of the balloon catheter and facilitating its delivery into the human body. Simultaneously, this angle also helps the mesh 111 to shrink back, facilitating the withdrawal of the balloon catheter from the human body.

[0051] When the balloon 200 inflates, the rhomboid mesh is stretched and deformed into an approximately square shape. To ensure that balloons 200 of different sizes can form a distinct concave-convex structure during inflatation, allowing calcified tissue to enter the groove 212 for easy insertion of the microneedle 112, and to ensure that the microneedle 112 can be contained within the mesh 111 before the balloon 200 inflates, the flat area S of the mesh 111 during inflatation is controlled to satisfy: 4mm² ≤ S ≤ 10mm². When the area S of the mesh 111 is too small, not only can the microneedles 112 not be contained within the mesh 111, but the height at which the balloon 200 bulges out of the mesh 111 is also reduced, affecting the formation of the occipital portion 211 and the groove portion 212. When the area S of the mesh 111 is too large, the height at which the balloon 200 bulges out of the mesh 111 is increased, the height difference h between the occipital portion 211 and the groove portion 212 is too large, and the adjacent occipital portions 211 are too close together, preventing calcified tissue from entering the groove portion 212 and affecting the insertion effect of the microneedles 112. At the same time, when the area of ​​the mesh 111 is increased, the number of mesh openings in the mesh body 11 will also decrease, resulting in a decrease in the number of microneedles 112, further affecting the drug delivery effect.

[0052] In some embodiments, the mesh body 11 and the microneedles 112 are integrally formed by cutting a metal tube, and the integral forming ensures a stable connection between the mesh body 11 and the microneedles 112. The metal tube can be made of a nickel-titanium alloy with shape memory properties and superelasticity, so that it can spring back to its initial state after the constraint bracket 100 expands.

[0053] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Although this application has disclosed preferred embodiments as above, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A restraint stent for restraining a balloon (200) laterally, characterized in that, The constraint support (100) includes a mesh body (11) and at least one microneedle (112) with a drug-loaded surface. The mesh body (11) has a plurality of mesh holes (111). The fixed end (1122) of the microneedle (112) is fixed to the mesh body (11). When the balloon (200) expands, a portion (21) of the balloon (200) protrudes from the mesh holes (111) to form a occipital portion (211). The occipital portion (211) can lift the free end (1121) of the microneedle (112) to a tilted state.

2. The constraint bracket according to claim 1, characterized in that, Before the balloon (200) expands, the microneedles (112) extend in a direction parallel to the proximal to distal direction of the mesh body (11).

3. The constraint bracket according to claim 2, characterized in that, The free end (1121) of the microneedle (112) points to the distal end of the mesh body (11).

4. The constraint bracket according to claim 2, characterized in that, Before the balloon (200) expands, the free end (1121) of the microneedle (112) does not extend beyond the outer periphery of the mesh body (11).

5. The constraint bracket according to claim 2, characterized in that, Along the direction from the free end (1121) to the fixed end (1122), the microneedle (112) sequentially includes a needle tip (1123), a needle body (1124), and a needle seat (1125), wherein the width of the needle seat (1125) is greater than the width of the needle body (1124), and the width of the needle body (1124) is greater than the width of the needle tip (1123).

6. The constraint bracket according to claim 5, characterized in that, Before the balloon (200) expands and unfolds, the mesh body (11) is in a flat state, the mesh (111) is rhomboid, and the fixed end (1122) is fixed to one of the interior angles of the rhomboid, the angle δ of the interior angle satisfies: 15°≤δ≤30°; After the balloon (200) expands and unfolds, the flat unfolded area S of the mesh (111) satisfies: 4mm2≤S≤10mm2.

7. The constraint bracket according to claim 6, characterized in that, The length L of the microneedle (112) satisfies: 1.5mm≤L≤3mm.

8. The constraint bracket according to claim 1, characterized in that, The outer surface of the mesh body (11) is loaded with a drug, and / or the outer surface of the balloon (200) is loaded with a drug.

9. The constraint bracket according to claim 1, characterized in that, When the balloon (200) expands, a concave groove (212) is formed between two adjacent occipital portions (211) on the balloon body (21), and the height difference h between the highest point of the occipital portion (211) and the lowest point of the groove (212) satisfies: 0.2mm≤h≤0.6mm.

10. A balloon catheter, characterized in that, It includes a balloon (200) and a restraint stent (100) as described in any one of claims 1-9.

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