Arteriovenous fistula flow field correction device with welding pressure ring and processing technology of arteriovenous fistula flow field correction device

Abstract

The invention discloses an arteriovenous fistula flow field correction device with a welding pressure ring and a processing technology of the arteriovenous fistula flow field correction device, and relates to the field of medical instruments. The device is used for supporting blood vessels of subcutaneous autologous internal arteriovenous fistula plasty of the upper arm and the front arm, specifically, the anastomotic artery blood vessels are brachial artery and radial artery, and the vein blood vessels are head veins. The device focuses on the convenience and safety in the actual production and use process, the device structure is innovatively designed, the operation convenience in the operation process is achieved, the implantation position of the device in the body is more accurate, the device is safer to the human body after implantation, and the effect is more obvious. The shaping mold is innovated in the process aspect, the production efficiency is improved, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the field of medical devices, and in particular to an arteriovenous fistula flow field correction device with a welding pressure ring and a processing technology thereof. Background Art

[0002] Globally, the number of patients with end-stage renal disease (ESRD) continues to increase. In 2020, the number of ESRD patients worldwide exceeded 12 million, and is expected to reach 14.5 million by 2030.

[0003] Patients with end-stage renal disease usually need hemodialysis to maintain their lives, and arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis because it has the characteristics of long service life and few complications. The maturation of AVF is an important process, which requires a period of vascular remodeling to provide sufficient blood flow and suitable puncture conditions. According to literature statistics, the primary patency rate of AVF is less than 50%, and the main reason is secondary thrombosis due to intimal hyperplasia stenosis, with stenosis near the anastomosis being the most common. In order to improve the primary patency rate of AVF and reduce the formation of secondary thrombosis due to intimal hyperplasia stenosis at the anastomosis, the present invention can correct hemodynamics by implanting an extravascular stent with a certain support function near the fistula, thereby effectively accelerating the maturation speed of the arteriovenous fistula and improving the success rate of maturation; at the same time, by correcting the local hemodynamic environment, reducing the generation of vortices and the distribution of retention areas, reducing the venous aneurysm-like expansion caused by continuous scouring of the veins due to blood flow, avoiding intimal hyperplasia and adverse remodeling at the anastomosis, and reducing the occurrence of complications such as mid- and long-term thrombosis and vascular stenosis. Summary of the invention

[0004] The purpose of the present invention is to provide an arteriovenous fistula flow field correction device with a welded pressure ring and a processing technology thereof. By implanting this device, the maturation failure of the arteriovenous fistula can be avoided from the root, the primary patency rate of the AVF can be improved, a good vascular access can be created for patients with end-stage renal disease (ESRD), and the life expectancy of dialysis patients can be increased.

[0005] The present invention is implemented by adopting the following technical scheme: an arteriovenous fistula flow field correction device with a welded pressure ring, comprising: a flow field corrector, a welded pressure ring and a flow limiting protection net, the flow field corrector is used to correct the blood flow direction of the arteriovenous fistula anastomosis, the flow field corrector is processed from a thin-walled nickel-titanium metal round tube, and is formed into a hollow cylindrical structure through laser cutting and heat treatment, comprising a non-deformation area of ​​the flow field corrector, a bending deformation area of ​​the flow field corrector and an expansion deformation area of ​​the flow field corrector; the The welding pressure ring is in the shape of a short circular tube, and an openable "J"-shaped opening is provided on its circumferential surface, and the two sides of the "J"-shaped opening are connected by mortise and tenon structures; the current limiting protection net is woven by multiple nickel-titanium filaments, and its appearance includes a cylindrical section and a conical section. The small end of the conical section is connected to the circular tube head end of the flow field corrector, and the diameter of the large end is 1.3-2 times the diameter of the small end, which is used to inhibit venous dilatation; the welding pressure ring presses and fixes the current limiting protection net on the flow field corrector, and then fixes it on the flow field corrector by spot welding.

[0006] Furthermore, the cylindrical section of the current limiting protection net is provided with a current limiting protection net bending zone, the weaving density of the non-bending area of ​​the current limiting protection net is 40-80 meshes, and the weaving density of the bending area of ​​the current limiting protection net is 70-130 meshes, so as to enhance support and compliance.

[0007] Furthermore, the spacing between the skeleton filaments and the connecting cross bars in the bending deformation area of ​​the flow field corrector is not less than 1 mm, so as to reduce the risk of breakage during shaping.

[0008] Furthermore, the "X"-shaped opening of the welding pressure ring before welding can be fully opened, and a complete closed circular ring can be formed after welding.

[0009] Furthermore, the ends of the nickel-titanium filaments of the current limiting protection net are cut off by laser melting and formed into molten ball heads to avoid piercing blood vessels or other tissues.

[0010] Furthermore, the flow field corrector is shaped by heat treatment through the angle corrector molding die body, the angle corrector molding die body is a variant T-shape, and an angle corrector molding die pressure ring and an angle corrector molding die adjustment nut are arranged on one end of the angle corrector molding die body, the angle corrector molding die adjustment nut and the angle corrector molding die pressure ring are arranged coaxially, one end of the flow field corrector is arranged between the angle corrector molding die pressure ring and the angle corrector molding die adjustment nut, and the flow field corrector is pushed by rotating the angle corrector molding die adjustment nut.

[0011] Furthermore, the processing technology of the arteriovenous fistula flow field correction device with a welded pressure ring comprises the following steps: Step 1: Feed the thin-walled nickel-titanium metal round tube into the laser cutting equipment, and cut out the basic structure of the flow field corrector and the welding pressure ring according to the drawing; Step 2: Fix the cut flow field corrector on the angle corrector shaping mold body, gradually adjust the mold structure, and complete shaping through multiple heat treatments to form an appearance including a non-deformed area of ​​the flow field corrector, a bent deformation area of ​​the flow field corrector, and an expanded deformation area of ​​the flow field corrector; Step 3: Use nickel-titanium filaments to weave the current limiting protection net alternately clockwise and counterclockwise on a weaving machine, and shape it through heat treatment, and then cut it and form a molten ball head at the end of the filament; Step 4: Sleeve the current limiting protection net on the cylindrical end of the flow field straightener, and sleeve the welding pressure ring on the joint between the current limiting protection net and the flow field straightener, and form a complete device through mortise and tenon structure and welding.

[0012] Furthermore, the shaping of the flow field corrector is completed by 2-3 steps of heat treatment, and the main body of the angle corrector shaping mold is a variant T-shape, and the angle and size can be adjusted to achieve precise control.

[0013] Furthermore, the surface treatment step includes placing the flow field straightener in a mixed solution of phosphoric acid and sulfuric acid for ultrasonic treatment, with the water temperature controlled at 60° C. for 4-5 minutes.

[0014] Furthermore, the current limiting protection net avoids secondary shaping by heat treatment of the mold consistent with the core shaft, thereby improving production efficiency and ensuring structural consistency.

[0015] The arteriovenous fistula flow field correction device with a welded pressure ring and the processing technology thereof described in the present invention have the following beneficial effects: 1. Improving the primary patency rate of AVF By implanting an arteriovenous fistula flow field correction device with a welded pressure ring, the hemodynamic environment of the arteriovenous fistula anastomosis can be effectively improved, the generation of eddy currents and retention areas can be reduced, thereby effectively accelerating the maturation of the arteriovenous fistula, improving its primary patency, and reducing complications caused by poor blood flow.

[0016] 2. Preventing varicose veins and vascular stenosis The flow-limiting protection net avoids venous dilatation caused by blood flow scouring by limiting the venous segment, especially near the anastomosis, effectively preventing venous aneurysm-like dilatation and abnormal proliferation of the vascular wall, and further reducing the risk of intimal hyperplasia and adverse remodeling at the anastomosis.

[0017] 3. Reduce thrombosis and related complications The device, through the combination of flow field corrector and flow limiting protection net, can avoid the failure of arteriovenous fistula maturation from the root and reduce the risk of thrombosis. At the same time, its design can effectively reduce the occurrence of mid- and long-term complications such as thrombosis and vascular stenosis, prolong the use time of vascular access, and improve the quality of life and life expectancy of dialysis patients.

[0018] 4. Enhance the stability of vascular access Through precise structural design and processing technology, the device provides stability of vascular access, especially optimization of blood flow direction at the arteriovenous anastomosis, which can effectively prevent vascular damage and delayed fistula maturation caused by hemodynamic imbalance.

[0019] 5. Strong adaptability and convenient for clinical application The device is made of nickel-titanium alloy, which has good biocompatibility and flexibility. It can provide good support inside and outside the blood vessels and form a firm fit with the vascular tissue. Its processing technology is simple and easy to mass produce, and it can be widely used in hemodialysis treatment of patients with end-stage renal disease (ESRD). BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0021] Figure 1 Shown is a posterior view of the unshaped angle corrector after cutting; Figure 2 Shown is a side view of the unshaped angle corrector after cutting; Figure 3 Shown is an oblique diagonal view of the unformed angle corrector after cutting; Figure 4 Shown is the current limiting protection net; Figure 5 Shown is an enlarged view of the end of a single nickel-titanium wire of the current-limiting protection net; Figure 6 Shown is a welded pressure ring having an expandable diameter configuration; Figure 7 Shown is a side view of the arteriovenous fistula flow correction device; Figure 8 The figure shows the front view assembly drawing of the angle corrector molding die; Fig. 9 The figure shows the front view cross-section assembly drawing of the angle corrector molding die; Fig.10 Shown is a front cross-sectional view of a braided mandrel of a current limiting protection net; Fig.11 Shown is a schematic diagram of an arteriovenous fistula in the lower arm without an implanted device; Fig.12 Shown is a schematic diagram of the position of the arteriovenous fistula flow field correction device implanted outside the blood vessel; In the figure, 1-flow field straightener, 11-symmetric surface on the cylindrical surface of the flow field straightener, 12-non-deformed area of ​​the flow field straightener, 13-bending deformation area of ​​the flow field straightener, 13a-bending deformation area one, 13b-bending deformation area two, 13c-bending deformation area three, 14-expansion deformation area of ​​the flow field straightener, 14a-expansion deformation area one, 14b-expansion deformation area two, 101-flow field straightener round tube head end, 102-flow field straightener skeleton filament, 102a-skeleton filament one, 102b-skeleton filament two, 102c-skeleton filament three, 102d-skeleton filament four, 103-flow field straightener connecting cross bar, 103a-connecting cross bar one, 103b connecting Crossbar 2, 103c-connecting crossbar 3, 103d-connecting crossbar 4, 103e-connecting crossbar 5, 103f-connecting crossbar 6, 104-front skeleton filament of flow field corrector expansion zone, 105-rear skeleton filament of flow field corrector expansion zone, 106-surgical suture foot, 107-outer diameter of the head end of the circular tube of flow field corrector, 108-inner diameter of the head end of the circular tube of flow field corrector, 2-current limiting protection net, 21-conical section of current limiting protection net, 22-cylindrical section of current limiting protection net, 23-bending area of ​​current limiting protection net, 24-the end with smaller opening of current limiting protection net, 25-the end with larger opening of current limiting protection net, 201-the end of nickel-titanium wire of current limiting protection net, 202-end protection process The end of a single nickel-titanium wire of the current limiting protection net after the end protection process, 203-the end of a single nickel-titanium wire of the current limiting protection net without end protection process treatment, 3-welding pressure ring, 31-a-shaped opening, 301-protruding metal wire, 302a-notched metal wire one, 302b-notched metal wire two, 4-angle corrector molding die body, 401-angle corrector molding die deflection angle, 402-angle corrector molding die bottom circle, 403-angle corrector molding die tail end, 404-angle corrector molding die head end, 405-angle corrector molding die threaded hole, 406-angle corrector molding die cylindrical end outer surface, 5-angle corrector molding die pressure ring, 501-angle corrector Inner surface of the molding die pressure ring, 6-angle corrector molding die adjustment nut, 7-current limiting protection mesh braided core shaft, 71-current limiting protection mesh braided core shaft upper limit flow protection mesh cylindrical section disconnection marking ring, 72a-current limiting protection mesh braided core shaft upper limit flow protection mesh conical section disconnection point 1, 72b-current limiting protection mesh braided core shaft upper limit flow protection mesh conical section disconnection point 2, 701-current limiting protection mesh braided core shaft connecting pin, 702-current limiting protection mesh braided core shaft connecting pin hole, 801-arteriovenous fistula head vein segment, 802-arteriovenous fistula head ligated vein segment, 803-arteriovenous fistula radial artery proximal end, 804-arteriovenous fistula radial artery distal end, 805-arteriovenous fistula anastomosis. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] like Figure 1-Figure 12 As shown, an arteriovenous fistula flow field correction device with a welded pressure ring and its processing technology, the device consists of a flow field corrector 1, a welded pressure ring 3 and a flow limiting protection net 2. The device is used for vascular support of subcutaneous autologous arteriovenous fistula plasty in the upper arm and forearm, and the specific anastomosed arteries and blood vessels are the brachial artery and radial artery, and the vein is the cephalic vein. The implantation position of the arteriovenous fistula flow field correction device is outside the blood vessel, located near the anastomosis 805 of the arteriovenous fistula. Most of the flow field corrector 1 is carried on the arterial segment at the anastomosis, and the head end 101 of the flow field corrector circular tube is partially sleeved on the venous segment at the anastomosis, which can correct the anastomotic angle of the artery and vein to an ideal state, correct the local hemodynamic environment, and reduce the generation of eddy currents and the distribution of the retention area. The flow limiting protection net 2 is sleeved on the venous segment at a certain distance from the anastomosis to prevent the venous segment near the anastomosis from being continuously flushed by blood flow, and to avoid hyperplasia and adverse remodeling of the anastomotic intima. By implanting this device, the maturation failure of arteriovenous fistula can be avoided from the root, the primary patency rate of AVF can be improved, good vascular access can be created for patients with end-stage renal disease (ESRD), and the life expectancy of dialysis patients can be increased.

[0025] The flow field corrector 1 is made of a thin-walled nickel-titanium round tube that is processed on a laser cutting machine and then fixed on a specific-shaped angle corrector molding mold body 4 and subjected to heat treatment to obtain the desired shape, and then pickled and polished to achieve the desired appearance. The flow field corrector 1 includes a symmetrical surface 11 on the cylindrical surface of the flow field corrector, a non-deformed area 12 of the flow field corrector, a bending deformation area 13 of the flow field corrector, an expansion deformation area 14 of the flow field corrector, a flow field corrector round tube head 101, a front end skeleton filament 104 of the expansion area of ​​the flow field corrector, a rear end skeleton filament 105 of the expansion area of ​​the flow field corrector, and a surgical suture foot 106. The bending deformation area 13 of the flow field corrector includes bending deformation area one 13a, bending deformation area two 13b, and bending deformation area three 13c. The expansion deformation area 14 of the flow field corrector includes expansion The hollow part on the flow field corrector 1 is composed of a flow field corrector skeleton filament 102 and a flow field corrector connecting cross bar 103. The flow field corrector skeleton filament 102 includes skeleton filament one 102a, skeleton filament two 102b, skeleton filament three 102c and skeleton filament four 102d. The flow field corrector connecting cross bar 103 includes connecting cross bar one 103a, connecting cross bar two 103b, connecting cross bar three 103c, connecting cross bar four 103d, connecting cross bar five 103e and connecting cross bar six 103f.

[0026] The welding pressure ring 3 is made of a thin-walled nickel-titanium round tube and can be processed on a laser cutting machine to obtain the desired shape. The welding pressure ring 3 is in the shape of a short round tube, and an openable "X"-shaped opening 31 is provided on its circumferential surface, and the two sides of the "X"-shaped opening 31 are connected by a mortise and tenon structure. The "X"-shaped opening 31 is composed of a protruding metal wire 301, a notch metal wire 1 302a, and a notch metal wire 2 302b.

[0027] The current limiting protection net 2 is a dense net made of multiple identical nickel-titanium cylindrical metal filaments on a braiding machine, and the appearance of the woven dense net is a combination of a section of cone and a section of cylinder. The diameter of the cylindrical section is consistent with the larger diameter of the conical section, and the larger cross-section at the end of the conical section coincides with the cross-section of the head end of the cylindrical section, wherein the diameter of the head end of the conical section is consistent with the outer diameter of the thin-walled nickel-titanium tube used to produce the flow field corrector 1. It is then placed in a hot-out furnace together with the current limiting protection net braiding mandrel 7 for finalization, and the conical end of the woven dense net is cut and trimmed after the finalization is completed. After the cylindrical end is cut, the nickel-titanium wire is melted under a laser to form a ball head. The current limiting protection net 2 includes a current limiting protection net conical section 21 and a current limiting protection net cylindrical section 22, and a current limiting protection net bending area 23 is provided on the current limiting protection net 2. The end 201 of the nickel-titanium wire of the current limiting protection mesh is melted under the laser to form a ball head, and the end 203 of the single nickel-titanium wire of the current limiting protection mesh without the end protection process is melted by the laser to become the end 202 of the single nickel-titanium wire of the current limiting protection mesh after the end protection process.

[0028] The current limiting protection net 2 is sleeved on the circular tube head end 101 of the flow field corrector, with the overlap length between 3-5mm, and then the welding pressure ring 3 is sleeved on the outer surface of the joint between the current limiting protection net 2 and the circular tube head end 101 of the flow field corrector, so that the surface of the ring split by the mortise and tenon structure can be in contact, and the metal wire protruding from the fracture can be re-welded together during welding, so that the welding pressure ring 3 can be re-formed into a circular ring with a larger diameter. Then align the welding pressure ring 3 with the upper end face of the flow field corrector 1, find 3-6 overlap points where the current limiting protection net 2 interferes, and weld them, so that the three components are fixed together, and the production of the arteriovenous fistula flow field correction device is completed.

[0029] The inner diameter of the thin-walled nickel-titanium round tube has a great correlation with the diameter of the target vein and target artery of the arteriovenous fistula. The inner diameter of the nickel-titanium tube should not be less than the diameter of the target vein and target artery, and the difference between the two values ​​should not be too large. According to the preoperative screening criteria for AVF and the blood vessel diameter of clinical statistics, the inner diameter of the nickel-titanium tube can be selected to be 2.5-8mm.

[0030] Thin-walled nickel-titanium round tubes require a certain wall thickness. If the wall thickness is too small, the device will produce a large strain when it is squeezed by tissue or subjected to the internal pressure of blood vessel expansion, causing the device to be unable to maintain the expected shape. However, if the wall thickness of the nickel-titanium tube is too thick, the force of the metal rod resisting expansion or bending will increase during the shaping process, making the shaping process difficult to implement and increasing the probability of fracture. The mechanical properties of the device are also related to the width, spacing, and distribution of the metal wires in the hollow cylindrical tube cut by the thin-walled tube laser.

[0031] The wall thickness of the thin-walled nickel-titanium round tube is α, the width of the hollow cylindrical tube metal wire is β, the spacing of the skeleton filaments in the bending zone is d, the length of the skeleton filaments in the deformation zone is L1, the distance between the head and tail of the skeleton filaments in the deformation zone is L2, the arc radius of the skeleton filament deformation zone is R, and the center angle of the skeleton filament deformation zone is ψψ<160°. The fracture coefficient S can be used to show the fracture of the thin-walled nickel-titanium round tube during deformation. The fracture here may be due to the external force on the thin-walled nickel-titanium round tube on the mold, or the fracture during high-temperature heat treatment.

[0032] The fracture coefficient calculation formula is as follows:

[0033] Through a large number of tests, when S < 0.25, the probability of metal rod fracture during the shaping process is significantly reduced. It should be noted that the fracture coefficient S is not only related to the material properties, but also to the stress of the thin-walled nickel-titanium round tube on the mold. For device drawings of different structures, the same calculation method can be used, but the fracture probability and fracture coefficient S may be different.

[0034] To ensure that the thin-walled nickel-titanium round tube has sufficient mechanical properties and consistency, its wall thickness α needs to be greater than 0.05 mm. To ensure that the flow field straightener 1 maintains a special morphological structure under the influence of external forces, the width of the metal wire of the hollow cylindrical tube should be no less than 0.15 mm.

[0035] The shape of the current limiting protection net 2 is a three-dimensional structure composed of a cylinder and an incomplete cone. The smaller diameter end of the current limiting protection net cone section 21 is consistent with the inner diameter of the thin-walled nickel-titanium tube, and the larger diameter end is 1.3-2 times the smaller end. The shape of the current limiting protection net 2 is formed by nickel-titanium filaments that are grouped and wound and woven in clockwise and counterclockwise rotation. The ratio of filaments in different rotation directions can be between 1:1 and 3:1, the number of nickel-titanium filaments can be 30-60, and the diameter is 25-100 microns.

[0036] The weaving density of the non-bending area of ​​the current limiting protection net 2 can be selected to be 40-80 meshes, and the weaving density of the bending area can be selected to be 70-130 meshes, so that the weaving density of the bending area is greater than the weaving density of the non-bending area, further increasing the support and compliance of the current limiting protection net 2.

[0037] The specific processing technology includes the following steps: Step 1: Cutting the flow field straightener 1 and the welding pressure ring 3: When cutting thin-walled nickel-titanium round tubes, inert gas argon is used to protect the metal to maintain its original luster. The laser uses a femtosecond laser with an energy range of 2w-10w.

[0038] Step 2: Weaving and heat setting of current limiting protection net 2: A plurality of identical nickel-titanium cylindrical metal filaments are made into a dense mesh on a braiding machine, and then put into a hot-out furnace together with the current-limiting protection mesh braiding mandrel 7 for shaping. After shaping, the conical section 21 of the current-limiting protection mesh is cut and trimmed, and after the cylindrical section 22 of the current-limiting protection mesh is cut, the nickel-titanium wire is melted under laser to form a ball head.

[0039] Step 3: Heat treatment and surface treatment of the flow field straightener 1 and the welding pressure ring 3: The cut flow field straightener 1 and welding pressure ring 3 are closely contacted with a specific mold, and after multiple different position adjustments and heat treatments, they reach the ideal shape. The finalized flow field straightener 1 and welding pressure ring 3 are placed in pickling liquid to remove the surface oxide layer, and then treated with electrolytic polishing liquid to ensure smoothness.

[0040] Step 4: Welding of components of the arteriovenous fistula flow field correction device: Sleeve the current limiting protection net 2 on the head end 101 of the flow field straightener, with an overlap length of 3-5mm. Sleeve the welding pressure ring 3 on the surface of the junction between the current limiting protection net 2 and the head end 101 of the flow field straightener, and fix them by welding. Find 3-6 overlap points without interference from the current limiting protection net 2, weld and fix the three components, and complete the device production.

[0041] The inner diameter 108 of the circular tube head of the flow field corrector is determined according to the largest value of the outer diameter of the arteriovenous fistula head vein segment 801 at the arteriovenous fistula anastomosis 805 and the arteriovenous fistula head ligated vein segment 802, the proximal end 803 of the radial artery of the arteriovenous fistula, and the distal end 804 of the radial artery of the arteriovenous fistula, that is, the inner diameter 108 of the circular tube head of the flow field corrector is not less than the outer diameter of the arteriovenous fistula head vein segment 801 and the radial artery of the arteriovenous fistula at the arteriovenous fistula anastomosis 805. The diameter of the target artery during the implantation of the arteriovenous fistula flow field correction device should be no less than 2.0 mm according to the AVF preoperative screening standard. According to the statistics of the brachial artery and radial artery detection data at the surgical site, the diameter of the target artery should be no more than 6.0 mm. The diameter of the target vein during the implantation of the arteriovenous fistula flow field correction device should be no less than 2.5 mm according to the AVF preoperative screening standard. According to the statistics of the cephalic vein detection data at the surgical site, the diameter of the target vein should be no more than 8.0 mm. Therefore, according to the above screening conditions, the inner diameter 108 of the flow field straightener round tube head should be between 2.5-8.0 mm. Then determine the wall thickness of the nickel-titanium tube, the difference between the outer diameter 107 of the flow field straightener round tube head and the inner diameter 108 of the flow field straightener round tube head, which can be selected as 0.1-0.2 mm. More preferably, the wall thickness can be selected as 0.1 mm, 0.15 mm, and 0.2 mm.

[0042] The flow field corrector skeleton filament 102, the flow field corrector connecting crossbar 103, the flow field corrector expansion area front skeleton filament 104 and the flow field corrector expansion area rear skeleton filament 105 should be selected with similar widths, so that the arteriovenous fistula flow field correction device has a more consistent flexibility as a whole and improves the ability to deform under external force. The optional width is between 0.15-0.35mm, and the rod width is adjusted differently according to the wall thickness of the thin-walled nickel-titanium tube. The distance between the flow field corrector skeleton filament 102a and the flow field corrector skeleton filament 3 102c affects the ability of the flow field corrector skeleton filament 102a and the flow field corrector skeleton filament 3 102c to resist the angle corrector molding die pressure ring 5 during molding. If the distance is too large, the flow field corrector skeleton filament 102a and the flow field corrector skeleton filament 3 102c will be twisted or have sharp protrusions. This situation is undesirable during molding. It is necessary to appropriately reduce the distance here to enhance the ability of the flow field corrector skeleton filament 102a and the flow field corrector skeleton filament 3 102c to resist the angle corrector molding die pressure ring 5 during molding. The optional distance is between 0.2-0.6mm.

[0043] The spacing between the connecting crossbar 4 103d and the connecting crossbar 5 103e of the bending deformation area 13a of the flow field straightener, and the connecting crossbar 2 103b and the connecting crossbar 3 103c of the bending deformation area 3 13c of the flow field straightener should be no less than a certain value to ensure that the resistance is small during bending and reduce the probability of breakage during the shaping process. The connecting crossbar 4 103d and the connecting crossbar 5 103e of the bending deformation area 13a of the flow field straightener, and the connecting crossbar 2 103b and the connecting crossbar 3 103c of the bending deformation area 3 13c of the flow field straightener should be no less than 1mm.

[0044] The angle corrector molding die body 4 includes an angle corrector molding die deflection angle 401, an angle corrector molding die bottom circle 402, an angle corrector molding die tail end 403, an angle corrector molding die head end 404, an angle corrector molding die threaded hole 405, an angle corrector molding die cylindrical end outer surface 406, an angle corrector molding die pressing ring 5, and an angle corrector molding die pressing ring inner surface 501. The angle corrector molding die deflection angle 401 determines the angle between the angle corrector molding die pressing ring 5 and the angle corrector molding die tail end 403 and the angle corrector molding die head end 404.

[0045] According to the surgical recommendations for arteriovenous fistula, the angle between the outer diameter of the arteriovenous fistula head vein segment 801 at the arteriovenous fistula anastomosis 805 and the proximal end 803 of the radial artery of the arteriovenous fistula should be 30-60°, which can improve the primary patency rate of the arteriovenous fistula. The central angle ψ of the bending deformation area 13a of the flow field corrector can be selected to range from 30-60°, and the deflection angle 401 of the angle corrector molding mold is 30-60°.

[0046] The current limiting protection net 2 will use nickel-titanium wires with a clockwise winding ratio of 1:1 to counterclockwise winding, so that the current limiting protection net 2 has better consistency in all directions. The diameter of the end 24 with a smaller opening of the current limiting protection net is not less than the outer diameter 107 of the head end of the circular tube of the flow field corrector. According to fluid mechanics simulation, the diameter of the end 25 with a larger opening of the current limiting protection net is between 1.3 and 2 times the diameter of the end 24 with a smaller opening of the current limiting protection net, which can reduce the stimulation of arterial blood flow on the inner wall of the venous blood vessel. Taking into account the convenience of surgery, the diameter of the end 25 with a larger opening of the current limiting protection net can be selected to be 1.5 times the diameter of the end 24 with a smaller opening of the current limiting protection net; the number of nickel-titanium filaments can be 30-60, and the diameter is between 0.05-0.1mm. The weaving density of the non-bending area of ​​the current limiting protection net can be selected from 40-80 meshes, and the weaving density of the bending area can be selected from 70-130 meshes.

[0047] After determining the structure of the arteriovenous fistula flow field correction device, the thin-walled nickel-titanium tube is placed on a laser cutting machine for cutting and processing, and the complete round tube is cut into an unformed flow field corrector 1 and a welding pressure ring 3. Then the unformed flow field corrector 1 is tightly combined with the angle corrector shaping mold body 4, and the angle corrector shaping mold body 4 is gradually shaped in 2-3 steps by adjusting the angle corrector shaping mold adjusting nut 6, so that the angle corrector is transformed into Figure 7 The appearance of the angle corrector. After shaping, the angle corrector is placed in a slag removal liquid containing 10:3 of phosphoric acid and pure sulfuric acid for ultrasonic slag removal for 4-5 minutes, and the water temperature is controlled at 60°C to remove the residual oxidation products on the surface. Then, it is placed in anhydrous ethanol for ultrasonic cleaning 3 times, each time for 1 minute, and then the surface is blown dry with compressed air. The angle corrector after slag removal is then placed in a polishing machine for electrolytic polishing to make the inner and outer surfaces of the angle corrector smooth.

[0048] The nickel-titanium wires are grouped according to a 1:1 clockwise and counterclockwise rotation, and are installed on braiding machines with different rotation direction bobbins respectively. The nickel-titanium wires are woven into a current limiting protection net 2 on the current limiting protection net braiding mandrel 7 according to the preset braiding distance and braiding density. The current limiting protection net 2 and the current limiting protection net braiding mandrel 7 are heat-treated and shaped together to obtain a current limiting protection net 2 that can spontaneously maintain its shape and is not cut. The current limiting protection net is cut along the current limiting protection net braiding mandrel upper limit current protection net cylindrical section disconnection marking ring 71 and the current limiting protection net braiding mandrel upper limit current protection net conical section disconnection point 1 72a and the current limiting protection net braiding mandrel upper limit current protection net conical section disconnection point 2 72b to obtain a single current limiting protection net 2, and then the end 25 of the current limiting protection net 2 with a larger opening is cut off by laser to form a ball head protection, and the production of the current limiting protection net 2 is completed. The current limiting protection net braiding core shaft 7 is provided with a current limiting protection net braiding core shaft connecting pin 701 and a current limiting protection net braiding core shaft connecting pin hole 702 Put the current limiting protection net 2 on the cylindrical end of the flow field corrector 1, and then put the welding pressure ring 3 on the outer surface of the joint between the current limiting protection net 2 and the circular tube at the head end of the flow field corrector 1, and then align the welding pressure ring 3 with the upper end face of the flow field corrector 1, find 3-6 overlapping points where the current limiting protection net 2 interferes, and weld them to fix the three components together, and finally weld the notch at the opening of the welding pressure ring 3 to complete the production of the arteriovenous fistula flow field correction device.

[0049] The specific processing steps of embodiment 1 are as follows: The first step is to select a nickel-titanium thin-walled metal round tube with a diameter of 5.8mm and send it into the laser cutting equipment, and make the cut flow field corrector 1 in accordance with the cutting drawings. The wall thickness of the nickel-titanium thin-walled metal round tube is 0.15mm and the inner diameter is 5.5mm. The width of the flow field corrector skeleton filament 102, the flow field corrector connecting crossbar 103, the flow field corrector expansion area front end skeleton filament 104 and the flow field corrector expansion area rear end skeleton filament 105 is selected to be 0.28mm. The spacing between the flow field corrector skeleton filament 1 102a and the flow field corrector skeleton filament 3 102c is selected to be 0.5mm, the spacing between the connecting crossbar 4 103d and the connecting crossbar 5 103e of the flow field corrector bending deformation area 13a is 1.3mm, and the spacing between the connecting crossbar 2 103b and the connecting crossbar 3 103c of the flow field corrector bending deformation area 3 13c is 3mm. The angle between the outer diameter of the arteriovenous fistula head vein segment 801 at the arteriovenous fistula anastomosis 805 and the proximal end 803 of the radial artery of the arteriovenous fistula is selected to be 45 degrees.

[0050] The second step is to select the number of nickel-titanium filaments of the current limiting protection net 2, which is 50, with a diameter of 0.06 mm, a weaving density of 60 mesh in the flying bending area, and a weaving density of 100 mesh in the bending area. The diameter of the end 24 with a smaller opening of the current limiting protection net is consistent with the outer diameter of the nickel-titanium thin-walled metal tube, which is 5.5 mm; the diameter of the end 25 with a larger opening of the current limiting protection net is 1.5 times the diameter of the end 24 with a smaller opening of the current limiting protection net, that is, a diameter of 8.25 mm.

[0051] In the third step, the unformed flow field corrector 1 is tightly combined with the angle corrector forming mold body 4, and the angle corrector is gradually formed toward the angle corrector forming mold body 4 in three steps by adjusting the angle corrector forming mold adjusting nut 6, so that the angle corrector is transformed into Figure 7 The appearance of the angle corrector. The angle corrector after shaping is placed in a slag removal liquid containing 10:3 of phosphoric acid and pure sulfuric acid for ultrasonic slag removal for 5 minutes, and the water temperature is controlled at 60°C to remove the residual oxidation products on the surface. Then it is placed in anhydrous ethanol for ultrasonic cleaning 3 times, 1 minute each time, and then the surface is blown dry with compressed air. The angle corrector after slag removal is then placed in a polishing machine for electrolytic polishing to make the inner and outer surfaces of the angle corrector smooth.

[0052] The fourth step is to group the nickel-titanium wires in a clockwise and counterclockwise direction of 1:1, install them on braiding machines with different rotation direction bobbins, and weave the nickel-titanium wires into a current limiting protection net 2 on the current limiting protection net braiding core shaft 7 according to the preset braiding distance and braiding density. Then, the current limiting protection net 2 and the current limiting protection net braiding core shaft 7 are heat-treated and shaped together to obtain a current limiting protection net 2 that can spontaneously maintain its shape and is not cut. The current limiting protection net is cut off along the current limiting protection net braiding core shaft at the disconnection mark ring 71 of the upper limit current protection net cylindrical section and the disconnection point of the upper limit current protection net conical section of the current limiting protection net braiding core shaft to obtain a single current limiting protection net 2, and then the end 25 of the current limiting protection net 2 with a larger opening is cut off by laser to form a ball head protection, and the production of the current limiting protection net 2 is completed.

[0053] The fifth step is to put the current limiting protection net 2 on the cylindrical end of the flow field corrector 1, and then put the welding pressure ring 3 on the outer surface of the junction between the current limiting protection net 2 and the circular tube at the head end of the flow field corrector 1, and then align the welding pressure ring 3 with the upper end face of the flow field corrector 1, find the four overlapping points where the current limiting protection net 2 interferes, and weld them to fix the three components together. Finally, weld the notch at the opening of the welding pressure ring 3 to complete the production of the arteriovenous fistula flow field correction device.

[0054] The specific processing steps of Example 2 are as follows: The first step is to select a nickel-titanium thin-walled metal round tube with a diameter of 4.0 mm and send it into the laser cutting equipment, and make the cut flow field straightener 1 in accordance with the cutting drawings. The wall thickness of the nickel-titanium thin-walled metal round tube is 0.15 mm and the inner diameter is 3.7 mm. The width of the flow field straightener skeleton filament 102, the flow field straightener connecting crossbar 103, the flow field straightener expansion area front end skeleton filament 104 and the flow field straightener expansion area rear end skeleton filament 105 is selected to be 0.24 mm. The spacing between the flow field straightener skeleton filament 1 102a and the flow field straightener skeleton filament 3 102c is selected to be 0.45 mm, the spacing between the connecting crossbar 4 103d and the connecting crossbar 5 103e of the flow field straightener bending deformation area 13a is 1.1 mm, and the spacing between the connecting crossbar 2 103b and the connecting crossbar 3 103c of the flow field straightener bending deformation area 3 13c is 2.4 mm. The angle between the outer diameter of the arteriovenous fistula head vein segment 801 at the arteriovenous fistula anastomosis 805 and the proximal end 803 of the radial artery of the arteriovenous fistula is selected to be 45 degrees.

[0055] The second step is to select 42 nickel-titanium filaments of the current limiting protection net 2, with a diameter of 0.06 mm, a weaving density of 50 mesh in the flying bending area, and a weaving density of 90 mesh in the bending area. The diameter of the end 24 with a smaller opening of the current limiting protection net is consistent with the outer diameter of the nickel-titanium thin-walled metal tube, which is 4.0 mm; the diameter of the end 25 with a larger opening of the current limiting protection net is 1.5 times the diameter of the end 24 with a smaller opening of the current limiting protection net, that is, a diameter of 6.0 mm.

[0056] In the third step, the unformed flow field corrector 1 is tightly combined with the angle corrector forming mold body 4, and the angle corrector is gradually formed toward the angle corrector forming mold body 4 in three steps by adjusting the angle corrector forming mold adjusting nut 6, so that the angle corrector is transformed into Figure 7 The appearance of the angle corrector. The angle corrector after shaping is placed in a slag removal liquid containing 10:3 of phosphoric acid and pure sulfuric acid for ultrasonic slag removal for 5 minutes, and the water temperature is controlled at 60°C to remove the residual oxidation products on the surface. Then it is placed in anhydrous ethanol for ultrasonic cleaning 3 times, 1 minute each time, and then the surface is blown dry with compressed air. The angle corrector after slag removal is then placed in a polishing machine for electrolytic polishing to make the inner and outer surfaces of the angle corrector smooth.

[0057] The fourth step is to group the nickel-titanium wires in a clockwise and counterclockwise direction of 1:1, install them on braiding machines with different rotation direction bobbins, and weave the nickel-titanium wires into a current limiting protection net 2 on the current limiting protection net braiding core shaft 7 according to the preset braiding distance and braiding density. Then, the current limiting protection net 2 and the current limiting protection net braiding core shaft 7 are heat-treated and shaped together to obtain a current limiting protection net 2 that can spontaneously maintain its shape and is not cut. The current limiting protection net is cut off along the current limiting protection net braiding core shaft at the disconnection mark ring 71 of the upper limit current protection net cylindrical section and the disconnection point of the upper limit current protection net conical section of the current limiting protection net braiding core shaft to obtain a single current limiting protection net 2, and then the end 25 of the current limiting protection net 2 with a larger opening is cut off by laser to form a ball head protection, and the production of the current limiting protection net 2 is completed.

[0058] The fifth step is to put the current limiting protection net 2 on the cylindrical end of the flow field corrector 1, and then put the welding pressure ring 3 on the outer surface of the junction between the current limiting protection net 2 and the circular tube at the head end of the flow field corrector 1, and then align the welding pressure ring 3 with the upper end face of the flow field corrector 1, find the four overlapping points where there is no interference from the current limiting protection net 2, and weld them to fix the three components together, and finally weld the notch at the opening of the welding pressure ring to complete the production of the arteriovenous fistula flow field correction device.

[0059] The above embodiments describe the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the changes and modifications made by those skilled in the art shall be within the scope of protection of the appended claims of the present invention without departing from the spirit and scope of the present invention.

Claims

1. An arteriovenous fistula flow field correction device with a welded pressure ring, characterized in that: include: The flow field corrector (1) is made of a thin-walled nickel-titanium metal round tube, and is formed into a hollow cylindrical structure through laser cutting and multiple heat treatments. The flow field corrector (1) comprises a flow field corrector non-deformation area (12), a flow field corrector bending deformation area (13) and a flow field corrector expansion deformation area (14); the welding pressure ring (3) is in the shape of a short round tube, and its outer peripheral surface is provided with a fully openable "J"-shaped opening (31), which is connected by a mortise and tenon structure to form a closed circular ring. The welding pressure ring (3) is connected by spot welding. The current limiting protection net (2) is firmly pressed on the flow field corrector (1) through the welding pressure ring (3), and is fixed by spot welding to form an integrated structure; the current limiting protection net (2) is woven from a plurality of nickel-titanium filaments, and comprises a current limiting protection net conical section (21) and a current limiting protection net cylindrical section (22), wherein the current limiting protection net is provided with a plurality of nickel-titanium filaments, and ... The end (24) with a smaller opening of the net is connected to the head end (101) of the flow field corrector circular tube, and the diameter of the larger end is 1.3-2 times that of the smaller end; the cylindrical section (22) of the current limiting protection net is completed by processing the current limiting protection net braiding mandrel integrated mold; the braiding density of the current limiting protection net (2) is divided into two parts: the braiding density of the non-bending area is 40-80 meshes; the braiding density of the current limiting protection net bending area (23) is 70-130 meshes; the flow field corrector (1) is gradually shaped by a mold step-by-step heat treatment process, the mold is composed of a variant T-shaped structure, and cooperates with the angle corrector shaping mold adjusting nut (6) and the angle corrector shaping mold pressure ring (5) to accurately control the bending and expansion shape of the flow field corrector (1); the braiding mandrel of the current limiting protection net (2) is integrated with the shaping mold, and the braiding and shaping process are completed simultaneously by heat treatment.

2. The arteriovenous fistula flow field correction device with a welded pressure ring according to claim 1, characterized in that: The spacing between the skeleton filaments and the connecting crossbars in the flow field straightener bending deformation area (13) of the flow field straightener (1) is not less than 1 mm, so as to reduce the risk of breakage during shaping.

3. The arteriovenous fistula flow field correction device with a welded pressure ring according to claim 1, characterized in that: The "J"-shaped opening (31) of the welding pressure ring (3) can be completely opened before welding, and forms a complete closed circular ring after welding.

4. The arteriovenous fistula flow field correction device with a welded pressure ring according to claim 1, characterized in that: The ends of the nickel-titanium filaments of the current limiting protection net (2) are cut off by laser melting and formed into molten ball heads to avoid piercing blood vessels or other tissues.

5. The arteriovenous fistula flow field correction device with a welded pressure ring according to claim 1, characterized in that: The flow field corrector (1) is heat-treated and shaped by an angle corrector shaping mold body (4); the angle corrector shaping mold body (4) is a variant T-shape; an angle corrector shaping mold pressure ring (5) and an angle corrector shaping mold adjustment nut (6) are arranged on one end of the angle corrector shaping mold body (4); the angle corrector shaping mold adjustment nut (6) and the angle corrector shaping mold pressure ring (5) are arranged coaxially; one end of the flow field corrector (1) is arranged between the angle corrector shaping mold pressure ring (5) and the angle corrector shaping mold adjustment nut (6); and the flow field corrector (1) is pushed by rotating the angle corrector shaping mold adjustment nut (6).

6. A process for manufacturing an arteriovenous fistula flow field correction device with a welded pressure ring as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: Feed the thin-walled nickel-titanium metal round tube into a laser cutting device, and cut out the basic structure of the flow field corrector (1) and the welding pressure ring (3) according to the drawing; Step 2: Fixing the cut flow field corrector (1) on the angle corrector shaping mold body (4), gradually adjusting the mold structure, and completing shaping through multiple heat treatments to form an appearance including a flow field corrector non-deformation area (12), a flow field corrector bending deformation area (13), and a flow field corrector expansion deformation area (14); Step 3: Using nickel-titanium filaments to weave the current limiting protection net (2) alternately in a clockwise and counterclockwise direction on a weaving machine, and shaping it through heat treatment, and then cutting it to form a molten ball head at the end of the filament; Step 4: Sleeve the current limiting protection net (2) on the cylindrical end of the flow field straightener (1), and sleeve the welding pressure ring (3) on the joint between the current limiting protection net (2) and the flow field straightener (1), and form a complete device through mortise and tenon structure cooperation welding.

7. The processing technology of the arteriovenous fistula flow field correction device with a welded pressure ring according to claim 6 is characterized in that: The shaping of the flow field corrector (1) is completed by 2-3 steps of step-by-step heat treatment, and the angle corrector shaping mold body (4) is a variant T-shape, and the angle and size can be adjusted to achieve precise control.

8. The processing technology of the arteriovenous fistula flow field correction device with a welded pressure ring according to claim 6 is characterized in that: The current limiting protection net (2) avoids secondary shaping by heat treatment of a mold consistent with the core shaft, thereby improving production efficiency and ensuring structural consistency.

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