Balloon, balloon catheter for thrombus extraction in blood vessel and forming method

Abstract

The invention relates to the technical field of medical instruments, in particular to a balloon catheter for thrombus extraction in a blood vessel. The invention provides a balloon, a balloon catheter for intravascular thrombus extraction and a balloon forming method, the balloon catheter comprises a balloon outer tube, an inner tube arranged on the inner side of the balloon outer tube and a balloon body arranged at the far end of the balloon outer tube, and a connecting piece is arranged at the near end of the balloon outer tube; the connecting piece is provided with an air inlet hole used for pressurizing the balloon body. The catheter further comprises the balloon body arranged at the far end of the catheter. Under the full condition, the balloon body comprises a middle section, head ends arranged on the two sides of the middle section and transition sections used for connecting the head ends and the middle section. The diameter of the middle section is larger than that of the head end, and the diameter of the transition section is gradually increased in the direction from the head end to the middle section. The transition section is in an arc shape which is sunken towards the center line direction of the balloon body. The technical problem that in the prior art, a common balloon is not easy to convey after pressure relief is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a balloon, a balloon catheter for intravascular thrombus removal, and a molding method. Background Art

[0002] With the aging of the population and the change of lifestyle, the incidence of thromboembolic diseases is increasing year by year. It includes arterial embolism, arterial thrombosis and venous thromboembolism. For mild thromboembolism, medical anticoagulation and thrombolysis can be used for treatment, but for acute arterial embolism and venous embolism with high thrombus load, medical treatment cannot quickly and effectively restore vascular patency. The current treatment options mainly include surgical vascular incision and embolectomy, interventional transcatheter contact thrombolysis and percutaneous mechanical embolectomy.

[0003] In vascular surgery emergencies, a large number of patients seek emergency treatment due to sudden venous thrombosis or arterial embolism. If such patients are not treated in time, once the embolism lasts too long, there is a risk of limb ischemia and amputation or even thrombus detachment leading to pulmonary embolism. Once this happens, it poses a huge threat to people's property and life safety. However, there are many problems with the consumables or equipment currently available on the market that can be used for thrombectomy and thrombus suction. For example, when using catheters such as Fogarty thrombectomy catheters for thrombectomy, it is often necessary to open the nearby blood vessels. The advantage is that the thrombectomy is thorough, but the disadvantage is that it causes great damage to the patient. Most patients require anesthesia, which invisibly increases the perioperative risk.

[0004] The Chinese invention patent with the announcement number CN102813995B disclosed a balloon microcatheter for treating cerebral vascular stenosis on March 12, 2014. The balloon microcatheter is a combination of a balloon catheter and a microcatheter. The balloon catheter is sleeved outside the microcatheter, and its inner wall and the outer wall of the microcatheter form an outer cavity. A balloon is provided at the front end of the outer cavity. The microcatheter is provided with balloon developing rings at both ends of the corresponding balloon and a tip developing ring at the tip. The inner cavity of the microcatheter serves as a delivery system for the stent. During the operation, the doctor first uses the balloon on the balloon catheter to pre-expand the vascular stenosis, and then withdraws the balloon from the original vascular stenosis. At the same time, as the device is withdrawn, the balloon-expandable stent or self-expandable stent is separated from the inner cavity of the microcatheter (the balloon-expandable stent needs to be slightly pushed forward), and is expanded and fixed at the original vascular stenosis to expand the blood vessel. This patent uses a balloon to dilate the narrowed area, but for clinical stenosis, most of the stenosis is that the stenosis is larger in the middle part and smaller at the two ends, that is, the middle part is more serious and the two ends are less serious. Ordinary balloons are not easy to deliver after decompression, so this balloon has certain limitations in use.

[0005] Therefore, it is necessary to propose a balloon catheter for intravascular thrombus removal that can better adapt to vascular stenosis. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide a balloon, a balloon catheter for intravascular thrombus removal and a molding method, which aims to solve the technical problem that ordinary balloons in the prior art are not easy to transport after decompression and have certain limitations.

[0007] To achieve the above-mentioned purpose, the present invention proposes a balloon, including a balloon body arranged at the distal end of a catheter; when inflated, the balloon body includes a middle section, head ends arranged on both sides of the middle section, and a transition section for connecting the head ends and the middle section; the diameter of the middle section is larger than the diameter of the head end, and the diameter of the transition section gradually increases from the head end to the middle section; the transition section is an arc-shaped body that is concave toward the center line of the balloon body.

[0008] Preferably, an elastic folding ring is provided on the transition section or the middle section; the cross section of the elastic folding ring comprises a woven mesh made of memory metal and coatings provided on upper and lower sides.

[0009] Preferably, the elastic folding ring is a ring formed by connecting a plurality of folding cells; in the non-pressurized process, the folding cells as a whole present a prism that is small at the bottom and large at the top.

[0010] Preferably, the folded unit cell includes a bottom surface and a trapezoidal surface arranged on the bottom surface, the bottom surface and the trapezoidal surface are connected to form a receiving groove, and an anti-inflammatory drug is coated on one side of the trapezoidal surface close to the bottom surface.

[0011] The present invention proposes a balloon catheter for intravascular thrombus removal, comprising the above-mentioned balloon, and also comprising a balloon outer tube, an inner tube arranged on the inner side of the balloon outer tube, and a balloon body arranged at the distal end of the balloon outer tube. A connecting piece is arranged at the proximal end of the balloon outer tube, and the connecting piece is provided with an air inlet hole for pressurizing the balloon body.

[0012] Preferably, the outer tube of the balloon is a polymer single-layer or multi-layer composite structure, and the multi-layer composite structure is composited by one or more processes such as hot melting, bonding, weaving, and extrusion molding.

[0013] Preferably, the outer tube of the balloon is a three-layer composite fiber braided mesh tube, which includes a middle layer of a polymer fiber braided mesh structure and inner and outer layers made of polymer materials.

[0014] Preferably, the outer tube of the balloon is a multi-layer co-extruded composite tube, and the layers are welded together by hot extrusion. The outer tube of the balloon includes a strength layer arranged on the inner side and a toughness layer arranged on the outer side.

[0015] Preferably, the outer tube of the balloon is a three-layer composite corrugated tube, which includes an outer layer made of a polymer material, a reinforced middle layer made of a metal material, and an inner layer made of a polymer material; the outer layer is made of polyurethane, the reinforced middle layer is made of one or more of stainless steel, cobalt-chromium alloy, and nickel-titanium alloy, and the inner layer is made of polytetrafluoroethylene.

[0016] Preferably, developing rings are provided at the proximal and distal ends of the balloon body, and the developing rings include one or more of barium sulfate and bismuth oxide. The developing rings also include nanomaterials, and the nanomaterials are one or more of silver, platinum and gold.

[0017] The present invention provides a method for forming a balloon, and the method comprises the following steps: S1. First cut a square of woven mesh, then cut off triangles of the same size from the four corners; S2, hot forging the woven mesh in S1 to form a pyramidal shape with a small bottom and a large top; S3, forming a coating on the woven mesh treated by S2 through an impregnation process; S4, stretching the tube blank on a tube stretching machine to generate a balloon bubble; S5. After placing the balloon material into the balloon forming machine mold, nitrogen is introduced to maintain the low pressure at 2.0-2.8MPa, and the mold temperature is gradually increased to 90-200°C; S6, performing a first biaxial stretching on the balloon material bubble in S5 under the adjusted pressure and temperature to form a cylindrical thin material bubble; S7, increase the pressure to 3.0-3.5MPa, gradually increase the mold temperature to above 230°C, keep the pressure and temperature unchanged, and perform a second biaxial stretching to form a thinner cylindrical thin material bubble; S8, cutting the cylindrical thin material bubble in S7 into multiple segments, placing two ends of the thin material bubble into a conical mold for cooling and demolding to obtain an open balloon with a transition segment, and cooling and demolding the other segments in a cylindrical mold; S9, axially sealing and bonding the balloon in S8 and the braided mesh in S3.

[0018] Compared with the prior art, the balloon and the balloon catheter for intravascular thrombus removal provided by the present invention have the following beneficial effects: 1. The cone angle formed at the balloon tip gradually increases along the axial direction. After the balloon is filled, the balloon tip forms a slightly inwardly concave cone. When the balloon of this structure is in a depressurized state, the sizes of both ends are smaller, which is more conducive to transportation.

[0019] 2. Mixing nanomaterials such as silver, platinum, and gold into polymer plastics as development markers can not only meet development needs, but also reduce the overall size of the development markers, reduce the impact on the size of the catheter, and better adapt to thinner blood vessels.

[0020] 3. By setting up an elastic folding ring, it can pause during the pressurization process. The toughness of the stenotic blood vessel wall is worse than that of the ordinary blood vessel wall. Every time the stenotic blood vessel wall expands a little, the blood vessel wall should be given time to adapt, that is, it needs to pause during the pressurization process to prevent the continuous change of the elastic force of the pressurization from causing the blood vessel wall to rupture.

[0021] The features and advantages of the present invention will be described in detail through embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention relates to a balloon catheter for intravascular thrombus removal according to the first embodiment of the present invention.

[0023] Figure 2 It is a schematic diagram of the structure of a common balloon in the first embodiment of the present invention.

[0024] Figure 3 It is a schematic diagram of the structure of the balloon with a concave transition section in the first embodiment of the present invention.

[0025] Figure 4 It is a schematic diagram of the structure of the balloon with a concave and longer transition section in the first embodiment of the present invention.

[0026] Figure 5 It is a cross-sectional view of a common balloon catheter in the second embodiment of the present invention.

[0027] Figure 6 It is a cross-sectional view of the balloon catheter of the three-layer composite fiber braided mesh tube in the second embodiment of the present invention.

[0028] Figure 7 It is a cross-sectional view of a balloon catheter of a multi-layer co-extruded composite tube in Example 2 of the present invention.

[0029] Figure 8 It is a diagram showing the structural changes of the common balloon catheter in Example 2 under normal conditions and when passing through a curve.

[0030] Fig. 9 It is a diagram showing the structural changes of the balloon catheter of the three-layer composite fiber braided mesh tube or the balloon catheter of the multi-layer co-extruded material composite tube in the second embodiment under normal conditions and when passing through a bend.

[0031] Fig.10 It is a schematic diagram of the change in the pipe cross section of the balloon catheter of the three-layer composite fiber braided mesh tube or the balloon catheter of the multi-layer co-extruded material composite tube in Example 2.

[0032] Fig.11This is a diagram showing the structural changes of the three-layer composite corrugated pipe in Example 2 under normal conditions and when passing through a curve.

[0033] Fig.12 It is a schematic diagram of the cross-sectional structure of the three-layer composite corrugated pipe in Example 2.

[0034] Fig.13 It is a schematic diagram of the cross-sectional structure of the elastic folding ring in the third embodiment.

[0035] Fig.14 It is a schematic diagram of the structure of the folded cell in the third embodiment.

[0036] Fig.15 Schematic diagram of the structure of the ring formed by folding cells in Example 3.

[0037] Fig.16 It is a cross-sectional view of the upper half of the balloon in Example 3 when it is set on the balloon outer tube and not expanded.

[0038] Fig.17 It is a cross-sectional view of the upper half of the part of the balloon disposed on the balloon outer tube when it is expanded in Example 3.

[0039] Fig.18 It is a cross-sectional view of the upper half of the balloon in the third embodiment when it is fully expanded and arranged on the balloon outer tube.

[0040] Fig.19 It is a schematic diagram of the structure of the woven mesh after S1 treatment in Example 4.

[0041] Fig. 20 It is a schematic diagram of the change of time-force (TF) of the stenotic blood vessel in Example 3.

[0042] in: 1-balloon outer tube; 11-middle layer; 12-strength layer; 13-toughness layer; 14-outer layer; 15-reinforced middle layer; 16-inner layer; 2-inner tube; 3-balloon body; 31-middle section; 32-head end; 33-transition section; 34-elastic folding ring; 341-folded cell; 342-bottom surface; 343-trapezoidal surface; 344-woven mesh; 345-coating; 35-developing ring; 4-connector; 41-air inlet. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below through the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0044] In the description of the present invention, it should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or indirectly connected to the other element.

[0045] In the description of the present invention, it should be noted that the terms "center", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the invention product is usually placed when in use, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third" and the like are only used to distinguish descriptions, and cannot be understood as indicating or implying relative importance. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

[0046] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] Embodiments of the present disclosure are now described in detail with reference to the accompanying drawings. As used herein, the term "clinician" refers to a doctor, surgeon, nurse, or any other care provider, and may include auxiliary personnel. The term "proximal end" will refer to the portion of the device or its components that is closer to the clinician, and the term "distal end" will refer to the portion of the device or its components that is farther away from the clinician. Embodiment 1

[0048] See also Figure 1An embodiment of the present invention provides a balloon catheter for intravascular thrombus removal, including a balloon, a balloon outer tube 1, an inner tube 2 arranged on the inner side of the balloon outer tube 1, and a balloon body 3 arranged at the distal end of the balloon outer tube 1, a connecting piece 4 is arranged at the proximal end of the balloon outer tube 1, and an air inlet hole 41 is provided on the connecting piece 4 for pressurizing the balloon body 3.

[0049] The balloon can use the currently available balloon. Figure 2 For the currently existing balloon, the balloon has a structure with smaller diameters at both ends and a larger diameter in the middle, and the size decreases axially from the middle to both ends. Usually, the balloon size has a nominal diameter of 1.00mm to 4.50mm, and an effective length range of 6mm to 35mm; the distance between the distal end of the balloon and the tip of the catheter body is 10mm to 50mm, which is suitable for most intravascular balloon application scenarios. Generally speaking, the cone angle formed at the head end of the balloon of this structure remains unchanged along the axial direction, or gradually decreases. After the balloon is filled, the tip of the balloon forms a cone that bulges slightly outward.

[0050] The balloon may be an optimized balloon of an existing balloon, see Figure 3 The balloon includes a balloon body 3 arranged at the distal end of a catheter (the catheter may be a balloon outer tube 1, or may be used for other catheters that can enter a blood vessel). When filled, the balloon body 3 includes a middle section 31, head ends 32 arranged on both sides of the middle section 31, and a transition section 33 for connecting the head ends 32 and the middle section 31. The diameter of the middle section 31 is greater than the diameter of the head end 32, and the diameter of the transition section 33 gradually increases from the head end 32 to the middle section 31. The transition section 33 is an arc that is concave toward the center line of the balloon body 3. The cone angle formed by the balloon head end gradually increases along the axial direction. After the balloon is filled, the tip of the balloon forms a cone that is slightly concave inward. The balloon of this structure is in a depressurized state, and the sizes of both ends are smaller, which is more convenient for transportation.

[0051] See also Figure 4 In an optional embodiment, another optimized structure of the balloon is that the angle formed by the head end is smaller, the transition area is longer, and the angle size transition is smoother (such as Figure 4 ), under this design, the length of the balloon tip can reach 10-200mm. The balloon includes a balloon body 3 arranged at the distal end of a catheter (the catheter can be a balloon outer tube 1, and can also be used for other catheters that can enter the blood vessel). When filled, the balloon body 3 includes a middle section 31, head ends 32 arranged on both sides of the middle section 31, and a transition section 33 for connecting the head ends 32 and the middle section 31. The diameter of the middle section 31 is larger than the diameter of the head end 32, and the diameter of the transition section 33 gradually increases from the head end 32 to the middle section 31. The transition section 33 is an arc that is concave toward the center line of the balloon body 3.

[0052] See also Figure 1 In an optional embodiment, a developing ring 35 is provided at both the proximal and distal ends of the balloon body 3, and the developing ring 35 includes one or more of barium sulfate and bismuth oxide. The developing ring 35 also includes nanomaterials, and the nanomaterials are one or more of silver, platinum, and gold. The developing marks of existing balloon catheters are all made of metal. Due to the limitations of material technology and other reasons, the wall thickness of the developing mark is relatively thick, resulting in an increase in the outer diameter of the catheter. Mixing nanomaterials such as silver, platinum, and gold into polymer plastics as developing marks can not only meet the development requirements, but also reduce the overall size of the developing mark, reduce the impact on the catheter size, and better adapt to thinner blood vessels.

[0053] 0For clinical stenosis, most of the stenosis is more severe in the middle part and less severe at the two ends, that is, the middle part is more serious and the two ends are less severe. For the two balloon morphology designs mentioned above, both have the advantage of a smaller head size. The balloon with this structural design provides a greater expansion force in the middle part where the stenosis ratio is greater, which is more conducive to opening the blood vessels and improving vascular lesions. And this design is easier to roll back to the initial state after decompression after filling, avoiding the wing flaps that are not fully retracted during withdrawal from scratching or slicing the blood vessels.

[0054] The balloon catheter of the present invention can be used in a variety of ways, and can be used in conjunction with an expansion stent or a thrombectomy stent.

[0055] When cooperating with the expansion stent: the balloon catheter passes through the narrow segment of the blood vessel along the guide wire, and the specific reasonable release position is determined by the developing ring. By applying positive pressure to the air inlet, the balloon is slowly filled in the narrow segment of the blood vessel, thereby expanding the narrow segment. Then, by applying negative pressure to the air inlet, the balloon is depressurized, the guide wire is withdrawn, and the expansion stent is delivered to the position from the inner cavity of the balloon microcatheter (i.e., the inner tube), and the balloon microcatheter is withdrawn as a whole. After the stent is positioned, it is released and the balloon microcatheter is continued to be withdrawn until the stent is completely released to the narrow segment, and then the narrow segment is expanded, and the balloon microcatheter and the push guide wire are withdrawn from the body.

[0056] When used in conjunction with a thrombectomy stent: the balloon catheter is moved within the blood vessel to the position where thrombectomy is required, positive pressure is applied to the air inlet, and the balloon is slowly inflated to achieve proximal vascular occlusion, the thrombectomy stent is transported from the inner tube to the distal end of the thrombus, the thrombectomy stent is completely released and thrombectomy is performed within the blood vessel, and after thrombectomy is completed, the thrombectomy stent is moved proximally back into the inner tube, and then the balloon catheter and the thrombectomy stent are withdrawn from the body at the same time. Embodiment 2

[0057] Based on the first embodiment, the structure of the balloon outer tube 1 is introduced in detail.

[0058] In an optional embodiment, the balloon body 3 is arranged at the distal end of the balloon outer tube 1, and the balloon outer tube is usually made of polymer to provide the necessary compliance and support for the balloon. The balloon outer tube 1 is a polymer single-layer or multi-layer composite structure, and the multi-layer composite structure is composited by one or more processes such as hot melting, bonding, weaving, and extrusion molding.

[0059] See also Figure 5 and Figure 8 In an optional embodiment, the outer tube 1 of the balloon may be a common balloon catheter. The common balloon catheter is usually a single-layer structure. When the single-layer tube is bent, a stress point is formed on the inner side of the bend, which is easy to bend and difficult to restore to its original state after the crease is formed. Even the crease formed after bending will have a sharp part that may pierce the blood vessel.

[0060] See also Figure 6 , Fig. 9 and Fig.10 In an optional embodiment, the balloon outer tube 1 does not select a single-layer structure. The balloon outer tube 1 is a three-layer composite fiber braided mesh tube, and the balloon outer tube 1 includes an intermediate layer 11 of a polymer fiber braided mesh structure and inner and outer layers made of polymer materials. The one-piece three-layer structure is formed by welding or hot pressing. The fiber braided mesh of the middle layer provides the necessary strength and flexibility, so that the pipeline has stronger support. When passing through a device with higher hardness such as a thrombectomy stent, it will not deform due to the large difference in hardness between the inner and outer tubes. The balloon outer tube 1 will not bend to form creases when it bends. Only the inner diameter at the bend becomes smaller, and the inner diameter changes from a circle to an ellipse. The cross-sectional area of ​​the lumen is reduced, which is not conducive to the thrombectomy and retraction.

[0061] See also Figure 7 , Fig. 9 and Fig.10 In an optional embodiment, the outer tube 1 of the balloon is a multi-layer co-extruded composite tube, and the layers are welded together by hot extrusion, which is more uniform than other multi-layer materials. The outer tube 1 of the balloon includes a strength layer 12 arranged on the inner side and a toughness layer 13 arranged on the outer side. The strength layer 12 is made of a high-strength material, and the toughness layer 13 is made of a high-toughness material, wherein the high-toughness material uses PTFE as a lining or a part of the lining. To achieve the advantageous performance of multi-layer materials, different flexibility and strength can be achieved by regulating their size and proportion. While ensuring that the two materials are tightly combined, multi-layer co-extruded materials can achieve higher strength and flexibility than single-layer materials at a smaller wall thickness (0.01-1mm).

[0062] See also Fig.11 and Fig.12In an optional embodiment, the outer tube 1 of the balloon is a three-layer composite bellows, which includes an outer layer 14 made of a polymer material, a reinforcing middle layer 15 made of a metal material, and an inner layer 16 made of a polymer material; the outer layer 14 is made of polyurethane, the reinforcing middle layer 15 is made of one or more of stainless steel, cobalt-chromium alloy, and nickel-titanium alloy, and the inner layer 16 is made of polytetrafluoroethylene. The bellows is composed of a plurality of segments and connecting segments between the segments. In this structure, when passing through a tortuous blood vessel, the connection between each segment bends, while the segment itself does not deform. The bellows is not easy to be folded or flattened when passing through a bend, the sacrificed area of ​​the lumen cross section is very small, the flexibility is better and it is not easy to break, and the lumen remains more complete when passing through a bend. Embodiment 3

[0063] On the basis of the first and second embodiments, since the balloon is expandable, a balloon with elasticity is generally selected. During the pressurization process, the balloon radially expands to open the narrow blood vessel. However, the toughness of the stenotic blood vessel wall is worse than that of the ordinary blood vessel wall. Each time the stenotic blood vessel wall expands a little, the blood vessel wall should be given time to adapt, that is, it needs to pause during the pressurization process to prevent the continuous change of the elastic force of the pressurization from causing the blood vessel wall to rupture.

[0064] In an optional embodiment, the present invention adds an elastic folding ring 34 to the balloon body 3, and the elastic folding ring 34 is arranged in the middle section 31 or the transition section 33. The elastic folding ring 34 can be used in an elastic balloon or an inelastic balloon. If the length of an ordinary balloon is too long, the strength will be reduced and it is easy to break. By setting the elastic folding ring 34, the balloon can be spliced, the length becomes longer and the strength remains unchanged, and it can be used in a longer vascular stenosis position.

[0065] See also Fig.13 In an optional embodiment, an elastic folding ring 34 is provided on the transition section 33 or the middle section 31. The cross section of the elastic folding ring 34 includes a woven mesh 344 made of memory metal and a coating 345 provided on the upper and lower sides. Both sides of the woven mesh 344 are sealed and connected to the balloon body 3, and the woven mesh 344 can maintain its original shape to prevent the balloon from being too loose and scratching the blood vessel wall when not pressurized. It can also prevent the balloon from being too deformed when turning and causing damage to the blood vessel.

[0066] See also Fig.14 In an optional embodiment, the elastic folding ring 34 is a ring formed by connecting a plurality of folding cells 341. Fig.15In the non-pressurized process, the folded cells 341 as a whole present a prism that is small at the bottom and large at the top. The folded cells 341 can be connected only by an arc-shaped guide wire, or the guide wire is not required, and the sides of the folded cells 341 are directly connected. The prism shape makes the balloon have elastic force in both the axial and radial directions, and the balloon can better maintain a taut state in the absence of pressure. In order to reduce the folded cells 341, the connection position of the folded cells 341 or the position in contact with the blood vessel can be polished into an arc shape.

[0067] See also Fig.14 In an optional embodiment, the folded cell 341 includes a bottom surface 342 and a trapezoidal surface 343 disposed on the bottom surface 342, the bottom surface 342 and the trapezoidal surface 343 are connected to form a receiving groove, and a drug is coated on one side of the trapezoidal surface 343 close to the bottom surface 342. Although the folded cell 341 is in contact with the blood vessel wall for a short time, in order to reduce complications or inflammation, drugs such as anti-proliferative drugs, endothelial-promoting drugs, anti-thrombotic drugs, and anti-inflammatory drugs are coated on the inside to enhance the therapeutic effect. Exemplary active agents are rapamycin or a derivative thereof, ABT-578, zotarolimus, everolimus, biolimus A9, deforolimus, temsirolimus, tacrolimus, pimcrolimus, nitric oxide synthase, C3 exoenzyme, RhoA inhibitor, tubulusin, A3 agonist, CB2 agonist, 17-AAG, Hsp90 antagonist, tyrphostins, cathepsin S inhibitor, paclitaxel or a derivative thereof, taxol, docetaxel, corticosteroids, glucocorticoids, dexamethasone, ceramide, dimethylsphingosine, ether-linked diglycerides, ether-linked phosphatidic acid, sphinganines, estrogens, taxol, taxol analogs. analogs), actinomycin D, prostaglandins, vitamin A, probucol, batimastat, statins, trapidil, mitomycin C and cytochalasin B, antiangiogenic agents, and antibodies.

[0068] Generally, after the balloon enters the narrow blood vessel wall, under pressure, part of the blood vessel wall will contact the receiving groove of the folded cell 341, and thus contact the coated drug. When the balloon shrinks, the receiving groove returns to a concave state, and the drug is not easy to fall off and remain in the body.

[0069] The wall thickness of the balloon outer tube 1 is generally around 0.5 mm, the wall thickness of the balloon is generally between 0.012 and 0.050 mm, and the diameter of the guide wire is generally around 0.01-0.1 mm. The height of the folded cell 341 formed by the guide wire is less than 0.3 mm, and both sides will not protrude from the balloon outer tube 1, and will not affect the function and effect of the balloon outer tube 1 itself.

[0070] Specific use process: After the balloon enters the narrow blood vessel wall, the initial state Fig.16 As shown in the figure. During the pressurization process, the balloon body expands first, and the narrowed blood vessels are stretched open during the expansion of the balloon body. At the beginning, the force to stretch the narrowed blood vessels is relatively small, and only the balloon body is needed. The elastic folding ring still maintains its original state, as shown in the figure. Fig.17 shown.

[0071] When the narrowed blood vessel is further dilated, the pressure is further increased. At this time, the blood vessel is in the pressure adaptation stage. If the pressure is increased rashly, it is likely to cause the blood vessel wall to rupture. However, in the process of further applying pressure, the pressure of the balloon body on the blood vessel wall does not increase further, but the elastic folded ring is stretched outward. Fig.18 shown.

[0072] When the elastic folded ring expands to touch the blood vessel wall, further pressure is applied, and the narrow blood vessel wall is further stretched to the appropriate position. Fig. 20 As shown. The elastic folding ring can be a memory metal and coated inside and outside. The elastic folding ring can be fixed to the balloon body by bonding. When the elastic folding ring is arranged in the middle section, its outer coating can be provided with anti-inflammatory drugs. Embodiment 4

[0073] The method for forming the balloon in the third embodiment comprises the following steps: S1. First cut a square of woven mesh, then cut off triangles of the same size from the four corners; S2, hot forging the braided mesh in S1 to form a prism shape with a small bottom and a large top, such as Fig.19 As shown; S3, forming a coating on the woven mesh treated by S2 through an impregnation process; S4, stretching the tube blank on a tube stretching machine to generate a balloon bubble; S5. After placing the balloon material bubble into the balloon forming machine mold, nitrogen is introduced to maintain the low pressure at 2.0-2.8MPa, and the mold temperature is gradually increased to 90-200°C; the optimum low pressure is maintained at 2.2MPa and the temperature is maintained at 150°C; S6, performing a first biaxial stretching on the balloon material bubble in S5 under the adjusted pressure and temperature to form a cylindrical thin material bubble; S7, increase the pressure to 3.0-3.5MPa, gradually increase the mold temperature to above 230℃, keep the pressure and temperature unchanged for the second biaxial stretching to form a thinner cylindrical thin bubble; the optimum pressure is maintained at 3.2MPa and the temperature is maintained at 250℃ for the second stretching; S8, cutting the cylindrical thin foam in S7 into multiple segments, placing two ends of the segments into a conical mold for cooling and demolding to obtain an open balloon with a transition section 33, and cooling and demolding the other segments in a cylindrical mold; S9, axially sealing and bonding the balloon in S8 and the braided mesh in S3.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A balloon, characterized in that: The invention comprises a balloon body (3) arranged at the distal end of a catheter; when filled, the balloon body (3) comprises a middle section (31), head ends (32) arranged at both sides of the middle section (31), and a transition section (33) for connecting the head ends (32) and the middle section (31); the diameter of the middle section (31) is larger than the diameter of the head end (32), and the diameter of the transition section (33) gradually increases from the head end (32) to the middle section (31); the transition section (33) is an arc-shaped indented in the direction of the center line of the balloon body (3); an elastic folding ring (34) is arranged on the transition section (33) or the middle section (31); the cross section of the elastic folding ring (34) comprises a woven mesh (344) made of memory metal and a coating (345) arranged on the upper and lower sides.

2. A balloon according to claim 1, characterized in that: The elastic folding ring (34) is a ring-shaped ring formed by connecting a plurality of folding cells (341); when no pressure is applied, the folding cells (341) are generally in the shape of a pyramid with a small bottom and a large top.

3. A balloon as claimed in claim 2, characterized in that: The folded cell (341) comprises a bottom surface (342) and a trapezoidal surface (343) arranged on the bottom surface (342), wherein the bottom surface (342) and the trapezoidal surface (343) are connected to form a receiving groove, and an anti-inflammatory drug is coated on one side of the trapezoidal surface (343) close to the bottom surface (342).

4. A balloon catheter for intravascular thrombus removal, characterized in that: The balloon comprises the balloon according to any one of claims 1 to 3, further comprising a balloon outer tube (1), an inner tube (2) arranged inside the balloon outer tube (1), and a balloon body (3) arranged at the distal end of the balloon outer tube (1), a connecting piece (4) being arranged at the proximal end of the balloon outer tube (1), and an air inlet hole (41) for pressurizing the balloon body (3) being provided on the connecting piece (4).

5. A balloon catheter for intravascular thrombus removal as claimed in claim 4, characterized in that: The balloon outer tube (1) is a polymer single-layer or multi-layer composite structure, and the multi-layer composite structure is composited by one or more processes such as hot melting, bonding, weaving, and extrusion molding.

6. A balloon catheter for intravascular thrombus removal as claimed in claim 4, characterized in that: The balloon outer tube (1) is a three-layer composite fiber braided mesh tube, comprising an intermediate layer (11) of a polymer fiber braided mesh structure and inner and outer layers made of polymer materials.

7. A balloon catheter for intravascular thrombus removal as claimed in claim 4, characterized in that: The balloon outer tube (1) is a multi-layer co-extruded composite tube, and the layers are welded together by hot extrusion. The balloon outer tube (1) comprises a strength layer (12) arranged on the inner side and a toughness layer (13) arranged on the outer side.

8. A balloon catheter for intravascular thrombus removal as claimed in claim 4, characterized in that: The balloon outer tube (1) is a three-layer composite corrugated tube, comprising an outer layer (14) made of a polymer material, a reinforcing middle layer (15) made of a metal material, and an inner layer (16) made of a polymer material; the outer layer (14) is made of polyurethane, the reinforcing middle layer (15) is made of one or more of stainless steel, cobalt-chromium alloy, and nickel-titanium alloy, and the inner layer (16) is made of polytetrafluoroethylene.

9. A balloon catheter for intravascular thrombus removal as claimed in claim 4, characterized in that: A developing ring (35) is provided at both the proximal end and the distal end of the balloon body (3). The developing ring (35) comprises one or more of barium sulfate and bismuth oxide. The developing ring (35) further comprises a nano material. The nano material is one or more of silver, platinum and gold.

10. A method for forming a balloon, for manufacturing the balloon as claimed in claim 2, characterized in that: The following steps are involved: S1. First cut a square of woven mesh, then cut off triangles of the same size from the four corners; S2, hot forging the woven mesh in S1 to form a pyramidal shape with a small bottom and a large top; S3, forming a coating on the woven mesh treated by S2 through an impregnation process; S4, stretching the tube blank on a tube stretching machine to generate a balloon bubble; S5. After placing the balloon material into the balloon forming machine mold, nitrogen is introduced to maintain the low pressure at 2.0-2.8MPa, and the mold temperature is gradually increased to 90-200°C; S6, performing a first biaxial stretching on the balloon material bubble in S5 under the adjusted pressure and temperature to form a cylindrical thin material bubble; S7, increase the pressure to 3.0-3.5MPa, gradually increase the mold temperature to above 230°C, keep the pressure and temperature unchanged, and perform a second biaxial stretching to form a thinner cylindrical thin material bubble; S8, cutting the cylindrical thin material bubble in S7 into multiple segments, placing two ends of the thin material bubble into a conical mold for cooling and demolding to obtain an open balloon with a transition section (33), and cooling and demolding the other segments in a cylindrical mold; S9, axially sealing and bonding the balloon in S8 and the braided mesh in S3.

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