A balloon-constrained stent and balloon catheter with asymmetric distal and proximal ends

Abstract

A proximal-distal asymmetric balloon restraint stent comprises a plurality of first axial restraint rods, a second axial restraint rod, a radial restraint ring, a proximal balloon connection ring and a distal balloon connection ring, wherein the first axial restraint rods and the second axial restraint rods are arranged circumferentially at intervals and n2 second axial restraint rods are arranged every n1 first axial restraint rods, wherein the value of n1 is greater than the value of n2, the radial restraint rings are arranged axially at intervals and connected to the first axial restraint rods and the second axial restraint rods, the proximal balloon connection ring is connected to the first axial restraint rod, and the distal balloon connection ring is connected to the second axial restraint rod. The product of the present invention has a simple structure and high strength, excellent pushing performance, realizes smooth delivery and withdrawal, and effectively prevents circumferential or radial deviation of the balloon during expansion, and is worthy of promotion and use in this field.

Description

Technical Field

[0001] The invention relates to the technical field of vascular interventional treatment, in particular to a distal-proximal asymmetric balloon restraint stent and a high-stability balloon catheter with the restraint stent. Background Art

[0002] For cardiovascular diseases, balloon angioplasty is one of the most commonly used treatments. Traditional balloon catheters are made into cylindrical balloons of different diameters and lengths according to the size of the patient's blood vessels and the length of the lesion. Its working principle is: using a delivery system, a balloon dilation catheter is placed at the lesion. After the balloon is inflated, the blood vessel is dilated to achieve lumen expansion. For example, a balloon catheter disclosed in the patent document with application number CN201621142062.7 includes a balloon and an inner tube. The balloon includes a first expansion area and a second expansion area. The diameter of the first expansion area is smaller than the diameter of the second expansion area; the first expansion area is located at the distal end of the balloon catheter, and the second expansion area is located at the proximal end of the balloon catheter; the first expansion area and the second expansion area are integrally formed; the first expansion area and the second expansion area increase the volume of the balloon by expansion to dilate the blood vessel. This solution is to introduce an expandable balloon into the diseased blood vessel for treatment.

[0003] However, traditional balloon angioplasty is often accompanied by vascular damage. For example, during the balloon expansion process, the proximal and distal diameters of the balloon are larger than the middle diameter of the balloon, which is the "dog bone effect". This causes the blood vessels in contact with the two ends of the balloon to over-expand, causing damage to the vascular wall and causing the longitudinal elongation of the balloon to accelerate vascular dissection (>30%). It can also cause acute vascular occlusion at the lesion site (5%~12%) and postoperative restenosis (50%).

[0004] Since traditional balloon angioplasty causes many vascular injuries, it is often used as an initial treatment for cardiovascular diseases, and bare stents or drug-eluting stents are often implanted for long-term treatment after the initial treatment. For example, a vascular stent disclosed in the patent document with application number CN201520377827.4 is a mesh cylinder, and the shape of the stent after release is consistent with the shape of the blood vessel. The stent has at least one maximum bend, and a radiopaque positioning part is provided at the maximum bend. The positioning part is provided with horizontal and vertical edges that intersect vertically, and the parallel ray projection lengths of the horizontal and vertical edges on the screen are equal. This solution is to introduce a separate vascular stent into the diseased blood vessel for treatment.

[0005] Although bare metal stents and drug-eluting stents have been shown to have better patency rates after treatment than balloon angioplasty, there are still adverse clinical outcomes and late restenosis after long-term implantation. In particular, the dynamic stress exerted on the stent by the lower limb arteries may lead to stent fracture or in-stent restenosis.

[0006] Therefore, there are currently non-long-term implantable products that, based on the traditional bare balloon, eliminate the previous "dog bone effect" by adding a constrained stent, and at the same time can reduce damage to the blood vessel wall, prevent excessive expansion, and the treatment effect is relatively better. For example, a balloon-expandable coated stent disclosed in the patent document with application number CN201821103084.1 includes a support stent and a coating covering the support stent; the support stent is tubular, and the tube wall is a hollow structure; the tube wall includes a plurality of broken line or curved closed rings spaced apart along the axial direction of the support stent, and two adjacent closed rings are connected by a connecting rod, and under the expansion action of the balloon placed on the inner side of the support stent, the support stent can expand outward along its radial direction to attach the coating to the blood vessel wall. During the research and development process, the applicant conducted in-depth research and practice on existing products and self-developed products, and found that the overall size of current similar products is relatively large, which is not conducive to implantation and pushing; further, although the structural strength of the main part is relatively high, the use process is often accompanied by the undesirable phenomenon of axial rod breakage at the proximal end of the metal mesh constraint stent; in addition, there is a "watermelon seed" effect during the balloon expansion process, that is, it may deviate axially or radially, which is not conducive to accurate positioning in the blood vessel. It is very difficult to achieve optimization in these multiple aspects at the same time, especially the balance between structural strength and size. Summary of the invention

[0007] One of the technical objectives of the present invention is to provide a proximal and distal asymmetric balloon-constrained stent to solve the problems of existing similar products being large in size, poor pushing, defective structural strength, and easy deviation during balloon expansion.

[0008] The specific technical scheme of the present invention is as follows: a proximal-distal asymmetric balloon restraint stent, comprising a plurality of first axial restraint rods, second axial restraint rods, radial restraint rings, a balloon proximal connecting ring and a balloon distal connecting ring, the first axial restraint rods and the second axial restraint rods are arranged circumferentially at intervals and n2 second axial restraint rods are arranged for every n1 first axial restraint rods, the value of n1 is greater than the value of n2, the radial restraint rings are arranged axially at intervals and connected to the first axial restraint rods and the second axial restraint rods, the proximal connecting ring of the balloon is connected to the first axial restraint rod, the distal connecting ring of the balloon is connected to the second axial restraint rod, the radial restraint ring, the first axial restraint rod and the second axial restraint rod form a tubular body and form a grid window on the tubular body, the tubular body is used to shrink or expand together with the wrapped balloon, and the grid window is used for the wrapped balloon to pass through after expansion to form a bulge.

[0009] Preferably, the distal end of the first axial constraint rod is connected to the radial constraint ring at the distal end of the tubular body, the proximal end of the first axial constraint rod is connected to the proximal connecting ring of the balloon, and the main body of the first axial constraint rod from its proximal end to the radial constraint ring at the proximal end of the tubular body forms a proximal transition constraint section.

[0010] Preferably, the proximal end of the second axial constraint rod is connected to the radial constraint ring at the proximal end of the tubular body, the distal end of the second axial constraint rod is connected to the distal connecting ring of the balloon, and the main body of the second axial constraint rod from its distal end to the radial constraint ring at the distal end of the tubular body forms a distal transition constraint section.

[0011] Preferably, each of the radial restraint rings is evenly divided into multiple sections by the first axial restraint rod and the second axial restraint rod, the portion of each of the first axial restraint rods located in the tubular body is evenly divided into multiple sections by the radial restraint ring, and the portion of each of the second axial restraint rods located in the tubular body is evenly divided into multiple sections by the radial restraint ring.

[0012] Preferably, one second axial restraint rod is arranged for every two first axial restraint rods.

[0013] Preferably, portions of the first axial restraint rod and the second axial restraint rod, respectively, located between adjacent radial restraint rings, are provided with bending portions.

[0014] Preferably, the bending portion includes an upslope section and a downslope section, and the upslope section and the downslope section on a single first axial restraint rod or on the first axial restraint rod are alternately arranged.

[0015] Preferably, the thickness and / or width of the radial constraint ring, the first axial constraint rod, and the second axial constraint rod is 0.04-0.25 mm.

[0016] Another technical purpose of the present invention is to provide a highly stable balloon catheter with a high-strength and small-sized restraint bracket, excellent pushing performance, and the balloon is not prone to deviation during expansion, which may affect positioning. Compared with existing products, it solves the problems of poor use effect and low stability.

[0017] A high-stability balloon catheter comprises a balloon and a restraining stent as described above, wherein the balloon is wrapped in the restraining stent, the balloon distal end connecting ring of the restraining stent is fixedly connected to the distal end of the balloon, and the balloon proximal end connecting ring of the restraining stent is fixedly connected to the proximal end of the balloon, and the tubular body of the restraining stent is used to follow the shrinkage or expansion of the balloon and cooperate with the grid window thereon to form a convex portion and a concave portion on the expanded balloon.

[0018] Preferably, the difference between the raised portion and the recessed portion is 0.10-0.35 mm.

[0019] The technical advantage of the present invention is that the balloon-constrained stent and the balloon catheter can not only ensure a high level of structural strength, but also be as simple as possible in structure and size, have excellent pushing performance, are not prone to stent rod breakage, can achieve smooth delivery and withdrawal, and effectively prevent circumferential or radial displacement of the balloon during expansion, so that it can be accurately positioned in the blood vessel. The overall use effect is better than the existing technology and is worthy of promotion and use in this field. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure in a collapsed state of an embodiment of the present invention;

[0021] Figure 2 It is a schematic diagram of the structure in a collapsed state without the radial restraining ring according to an embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of the expansion state structure of an embodiment of the present invention;

[0023] Figure 4 for Figure 1 A is an enlarged schematic diagram;

[0024] The names of the parts corresponding to the numbers in the figure are: 1-first axial constraint rod, 11-proximal transition constraint segment, 2-second axial constraint rod, 21-distal transition constraint segment, 3-radial constraint ring, 4-balloon proximal connecting ring, 5-balloon distal connecting ring, 6-tubular body, a-first straight line segment, b-folded segment, c-second straight line segment, d-bending portion, d1-uphill segment, d2-downhill segment. DETAILED DESCRIPTION

[0025] The present invention will be further described below by means of specific embodiments in conjunction with the accompanying drawings:

[0026] An embodiment of a high-stability balloon catheter device includes a balloon (omitted and not shown in the figure) and a distal-proximal asymmetric constraint bracket, the balloon is wrapped in the constraint bracket, the balloon distal end connecting ring 5 of the constraint bracket is fixedly connected to the distal end of the balloon, the balloon proximal end connecting ring 4 of the constraint bracket is fixedly connected to the proximal end of the balloon, and the tubular body 6 of the constraint bracket is used to follow the shrinkage or expansion of the balloon and cooperate with the grid window thereon to form a convex part and a concave part of the expanded balloon. The constraint bracket fits tightly with the balloon, and as the balloon expands, an expansion structure different from the traditional naked balloon is formed.

[0027] The constrained stent is a metal mesh stent, which is cut from a metal tube with a memory function or woven from a metal alloy wire with a memory function. In this embodiment, nickel-titanium alloy is used. The nickel-titanium alloy material itself has good elastic stretching (about 6% to 15%), which allows it to withstand the deformation requirements imposed by the balloon on the constrained stent, and allows the constrained stent to expand within the elastic deformation range. The balloon is a semi-compliant balloon, and its expansion strength range is between 8 and 30 atmospheres. The elasticity of the constrained stent is lower than that of the balloon, so as to limit the expansion of the balloon, avoid excessive expansion, and damage the blood vessels, and also to form the morphology of the convex part and the concave part (the entity part of the constrained stent presses the balloon to form a relative concave part, and the grid window of the constrained stent allows the balloon part to expand and bulge to form a relative convex part), which is also one of the design points of the structure. The constrained stent expands in the radial direction as the balloon expands, and has no substantial elongation in the axial direction (the elongation rate is different and is controlled between 93% and 99% according to the length of the balloon), preferably controlled at 96% to 99%. The difference between the raised and recessed parts of the constrained stent after it is fully expanded is 0.10~0.35mm. In the past, when the balloon was expanded in the blood vessel, every part of the balloon surface expanded synchronously and evenly. The balloon would squeeze a certain plaque completely flatly outward, causing the blood vessel to be over-expanded and easily damaged. However, the raised and recessed parts in this solution ensure that not every part of the plaque is completely squeezed outward, but part of it enters the recessed part, which can reshape the blood vessel. After the blood vessel is expanded, the shape of the plaque is optimized, and it is not easy to over-expand or even damage the blood vessel.

[0028] See Figure 1 , Figure 2 , Figure 3In this embodiment, the constraint bracket includes a first axial constraint rod 1, a second axial constraint rod 2, a radial constraint ring 3, a proximal balloon connection ring 4 and a distal balloon connection ring 5. The first axial constraint rod 1 and the second axial constraint rod 2 are arranged at intervals in the circumferential direction and n2 second axial constraint rods 2 are arranged every n1 first axial constraint rods 1, the value of n1 is greater than the value of n2, and the preferred n1=2 and n2=1 in the figure; the radial constraint ring 3 is arranged at intervals in the axial direction and is connected to the first axial constraint rod 1 and the second axial constraint rod 2, the proximal balloon connection ring 4 is connected to the first axial constraint rod 1, and the distal balloon connection ring 5 is connected to the second axial constraint rod 2, the radial constraint ring 3, the first axial constraint rod 1, and the second axial constraint rod 2 form a tubular body 6 and form a grid window on the tubular body, the tubular body 6 is the main expandable part corresponding to the balloon, the tubular body 6 is used to shrink or expand together with the wrapped balloon, and the grid window is used for the wrapped balloon to pass through after expansion to form a bulge. The thickness and / or width of the radial restraint ring 3, the first axial restraint rod 1, and the second axial restraint rod 2 are 0.04~0.25mm. The stent in this scheme is conventionally made by cutting and forming. All three are square rods, so there are differences in thickness and width. If the entire stent is woven into the form of braided wire, the thickness and width of these three can be considered to be their diameters.

[0029] Specifically, the distal end of the first axial constraint rod 1 is connected to the radial constraint ring 3 at the distal end of the tubular body 6, the proximal end of the first axial constraint rod 1 is connected to the proximal connection ring 4 of the balloon, and the main body of the first axial constraint rod 1 from its proximal end to the radial constraint ring 3 at the proximal end of the tubular body 6 forms a proximal transition constraint section 11; the proximal end of the second axial constraint rod 2 is connected to the radial constraint ring 3 at the proximal end of the tubular body 6, the distal end of the second axial constraint rod 2 is connected to the distal connection ring 5 of the balloon, and the main body of the second axial constraint rod 2 from its distal end to the radial constraint ring 3 at the distal end of the tubular body 6 forms a distal transition constraint section 21. The proximal connection ring 4 and the distal connection ring 5 of the balloon are used to fix the proximal end and the distal end of the balloon respectively, and the specific fixing method can be selected from welding, hot melting or bonding, etc.

[0030] The two axial constraint rods axially penetrate the entire constraint bracket. The axial constraint rods are both components that constitute the tubular body 6 and components that connect the two connecting rods at the proximal and distal ends of the balloon, which can reduce the overall size of the bracket as much as possible. The number of the second axial constraint rods 2 is less than the number of the first axial constraint rods 1, that is, the number of the distal transition constraint segments 21 will be less than the proximal transition constraint segments 11. Since the distal end of the balloon catheter is used as the first to push, the smaller the size of this part, the better the pushability, so the second axial constraint rods 2, that is, the number of the distal transition constraint segments 21, are intentionally reduced during design, which can reduce the size in the circumferential direction and facilitate pushing. In contrast, the number of the proximal transition constraint segments 11 is relatively more, in order to solve the problem of rod breakage when the balloon catheter is withdrawn. The applicant found that structural fractures often occur during the withdrawal of the balloon catheter, and often the proximal axial constraint rod part breaks. This is actually because the proximal part of the bracket will be subjected to excessive force during the withdrawal process, so the number of the first axial constraint rods 1 is relatively increased. Such a setting can not only make the overall size of the stent as small as possible, but also ensure the structural strength of the tubular body 6 and the proximal end of the stent, and also ensure the smoothness of the stent push. In addition, as the balloon catheter is withdrawn into the catheter, the stent is squeezed from the proximal end to the distal end, such as the constraint rod will be stressed to appear wavy deformation, and will be accumulated at the distal end of the balloon, which will be difficult or even impossible to withdraw smoothly. The design of the relatively small distal transition constraint section 21 of this scheme can alleviate this situation. In this embodiment, a simple example is given of the method of setting one second axial constraint rod 2 every two first axial constraint rods 1. This setting is to keep the size as small as possible in structure, the material amount is more reasonable and more economical, and at the same time ensure that the above-mentioned purpose can also be achieved. Of course, the number of the first axial constraint rod and the second axial constraint rod can be increased (to ensure that the number of the former is greater than the latter and is arranged in an orderly and uniform interval). The design can be selected according to the actual situation, such as according to the size of the diseased blood vessel, the actual structural strength required for the operation, and other conditions.

[0031] Each radial constraint ring 3 is evenly divided into multiple sections by the first axial constraint rod 1 and the second axial constraint rod 2. The portion of each first axial constraint rod 1 in the tubular body 6 is evenly divided into multiple sections by the radial constraint ring 3. The portion of each second axial constraint rod 2 in the tubular body 6 is evenly divided into multiple sections by the radial constraint ring 3. The "evenly divided into multiple sections" here does not mean that each section is absolutely equal in length. In fact, the ratio of any two sections of each radial constraint ring 3 or each first axial constraint rod 2 or each second axial constraint rod 2 is 1:1~1.2, preferably 1:1. It is intended to illustrate that the shape of each grid window is basically the same, that is, the shape and length of the corresponding side segment of each grid window are basically the same, so as to ensure the uniformity of the main structure of the stent after expansion, that is, the uniformity of the concave and convex parts after balloon expansion.

[0032] Some existing similar products already have the "watermelon seed" effect, and the aforementioned design in this embodiment actually also has the phenomenon of deviation during the balloon expansion process. Therefore, in order to solve the defects brought about by this, the applicant has also made improvements to the radial restraint ring 3 that are specifically adapted to this solution. After the restraint stent is expanded and shaped, the radial restraint ring 3 between adjacent first axial restraint rods 1 is a folded segment b, and the angle of the folded segment b is an obtuse angle, and the angle is between 90 and 160 degrees. After the restraint stent is expanded and shaped, the radial restraint ring 3 between the adjacent first axial restraint rod 1 and the second axial restraint rod 2 is a straight segment. See Figure 4 In this embodiment, the radial constraint ring 3 between each second axial constraint rod 2 and the two adjacent first axial constraint rods 1 on both sides is respectively the first straight line segment a or the second straight line segment c, and the radial constraint ring 3 between the two adjacent first axial constraint rods 1 is the folding segment b. The length ratio of the first straight line segment a, the folding segment b, and the second straight line segment c is preferably 1:1:1. The straight line segments a and c are combined with the folding segment b and the length design of each segment to make the size as small as possible, while the structural strength is ensured, and the folding segment b is used to apply a uniformly dispersed shear force to the balloon surface. Compared with the straight line segments a and c, the folding segment b makes it more difficult for the balloon to slide along the axial direction or radial direction of the stent during the expansion process, so as to achieve the overall precise positioning at the lesion site and eliminate the "watermelon seed" effect of the traditional balloon during the expansion process.

[0033] In addition, in order to further prevent the deviation during balloon expansion, the following improvement is made, that is, the first axial constraint rod 1 and the second axial constraint rod 2 are each provided with a bending portion d on the part located between the adjacent radial constraint rings 3, and the bending portion d includes an upslope section d1 and a downslope section d2, and the upslope section d1 and the downslope section d2 on a single first axial constraint rod 1 or the first axial constraint rod 1 are alternately arranged. The existence of the bending portion d is to constrain the stent to have a stretching margin in the process of expansion with the expansion of the balloon, and the stretching margin can compensate for the radial shortening phenomenon that may occur in the constraint structure during the expansion process, ensuring that the length of the constrained stent is not substantially shortened in both the non-expanded state and the expanded state of the product; at the same time, the upslope section d1 and the downslope section d2 also have a uniformly dispersed shear force on the surface of the gun. Compared with the straight axial constraint rod, the balloon is less likely to slide along the axial direction or radial direction of the stent during the expansion process, further eliminating the "watermelon seed" effect and improving the positioning accuracy.

[0034] It should be understood by those skilled in the art that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be deformed or modified in any way without departing from the principles.

Claims

1. A balloon-constrained stent with asymmetric distal and proximal ends, characterized in that: The invention comprises a plurality of first axial constraint rods (1), second axial constraint rods (2), radial constraint rings (3), a proximal connection ring (4) of a balloon and a distal connection ring (5) of a balloon. The first axial constraint rods (1) and the second axial constraint rods (2) are arranged at intervals in the circumferential direction and n2 second axial constraint rods (2) are arranged every n1 first axial constraint rods (1), wherein the value of n1 is greater than the value of n2. The radial constraint rings (3) are arranged at intervals in the axial direction and are connected to the first axial constraint rods (1) and the second axial constraint rods (2). The proximal connection ring (4) of the balloon is connected to the first axial constraint rod (1), and the distal connection ring (5) of the balloon is connected to the second axial constraint rod (2). The radial constraint rings (3), the first axial constraint rods (1) and the second axial constraint rods (2) form a tubular body (6) and a grid window is formed on the tubular body. The tubular body (6) is used to shrink or expand together with the wrapped balloon. The grid window is used for the wrapped balloon to pass through after expansion to form a bulge.

2. The proximal-distal asymmetric balloon-constrained stent according to claim 1, characterized in that: The distal end of the first axial constraint rod (1) is connected to the radial constraint ring (3) at the distal end of the tubular body (6), the proximal end of the first axial constraint rod (1) is connected to the proximal connecting ring (4) of the balloon, and the main body of the first axial constraint rod (1) from its proximal end to the radial constraint ring (3) at the proximal end of the tubular body (6) forms a proximal transition constraint section (11).

3. The proximal-distal asymmetric balloon-constrained stent according to claim 1, characterized in that: The proximal end of the second axial restraint rod (2) is connected to the radial restraint ring (3) at the proximal end of the tubular body (6), the distal end of the second axial restraint rod (2) is connected to the distal connecting ring (5) of the balloon, and the main body of the second axial restraint rod (2) from its distal end to the radial restraint ring (3) at the distal end of the tubular body (6) forms a distal transition restraint section (21).

4. The proximal-distal asymmetric balloon-constrained stent according to claim 1, characterized in that: Each of the radial restraint rings (3) is evenly divided into multiple sections by the first axial restraint rod (1) and the second axial restraint rod (2); a portion of each of the first axial restraint rods (1) located in the tubular body (6) is evenly divided into multiple sections by the radial restraint ring (3); and a portion of each of the second axial restraint rods (2) located in the tubular body (6) is evenly divided into multiple sections by the radial restraint ring (3).

5. The proximal-distal asymmetric balloon-constrained stent according to claim 1, characterized in that: One of the second axial restraint rods (2) is arranged every two of the first axial restraint rods (1).

6. The proximal-distal asymmetric balloon-constrained stent according to claim 1, characterized in that: The first axial restraint rod (1) and the second axial restraint rod (2) are each provided with a bent portion (d) on their respective portions located between adjacent radial restraint rings (3).

7. The proximal-distal asymmetric balloon-constrained stent according to claim 6, characterized in that: The bending portion (d) comprises an upslope section (d1) and a downslope section (d2), and the upslope section (d1) and the downslope section (d2) on a single first axial constraint rod (1) or on the first axial constraint rod (1) are arranged alternately.

8. The proximal-distal asymmetric balloon-constrained stent according to claim 1, characterized in that: The thickness and / or width of the radial constraint ring (3), the first axial constraint rod (1), and the second axial constraint rod (2) is 0.04-0.25 mm.

9. A balloon catheter, comprising a balloon, characterized in that: It also includes a balloon restraint stent as described in any one of claims 1 to 8, wherein the balloon is wrapped in the balloon restraint stent, the balloon distal connection ring (5) of the balloon restraint stent is fixedly connected to the distal end of the balloon, the balloon proximal connection ring (4) of the balloon restraint stent is fixedly connected to the proximal end of the balloon, and the tubular body (6) of the balloon restraint stent is used to follow the shrinkage or expansion of the balloon and cooperate with the grid window thereon to form a convex portion and a concave portion on the expanded balloon.

10. A balloon catheter according to claim 9, characterized in that: The height difference between the protruding portion and the recessed portion is 0.10-0.35 mm.

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