A degradable extravascular stent and its system and control method

Abstract

The present invention discloses a degradable extravascular stent and a system and a control method thereof. The degradable extravascular stent system comprises: a main stent covering the arterial end, wherein the material density of the main stent is 50-300 mg / cm 3 ; A side sleeve covering the venous end, the side sleeve is connected to the main stent, and the angle between the side sleeve and the main stent is adjustable, the adjustment range of the angle is 20-70°, the main stent and the side sleeve are in an open state with a complete circular shape along the extension direction of the tube wall, and the stent is covered on the arteriovenous fistula after adjusting the angle of the internal fistula during the operation, and the two sides of the opening are fixed with interlocking devices after the stent is closed; the side sleeve and the main stent are made of biodegradable polymers, the main stent and the side sleeve are drug-loaded / not drug-loaded, and the elastic modulus of the biodegradable polymer is 100MPa-1000MPa.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a degradable extravascular stent and a system and a control method thereof. Background Art

[0002] With the improvement of patients' medical awareness and the development of medical equipment in my country, domestic uremia patients have a deeper understanding of hemodialysis, and the number of patients receiving hemodialysis has gradually increased. Therefore, with the continuous improvement of the national medical insurance system, the number of patients undergoing maintenance hemodialysis will continue to grow rapidly.

[0003] The prerequisite for terminal patients to undergo hemodialysis is to establish an effective extracorporeal dialysis access. Blood is drawn from the arterial access, purified, and returned to the vein or synthetic graft, so that toxins in the patient's blood are removed and a suitable balance in the body is maintained, thus prolonging the patient's life. In clinical practice, autologous arteriovenous fistula (AVF) or vascular graft fistula (AVG) access is usually used to provide hemodialysis patients with the blood access required for dialysis. The purpose of arteriovenous fistula surgery is to achieve arterial superficialization, that is, to introduce arterial blood into the superficial veins, so that the blood in the artery can flow into the vein through the anastomosis. Doctors puncture the veins to obtain blood with a higher flow rate and speed for dialysis.

[0004] Currently, more than 90% of hemodialysis accesses are established using the AVF surgical method, that is, doctors construct accesses in the patient's limbs through surgery, and blood flows directly from the artery to the vein through the fistula. Arterial blood pressure higher than venous pressure, together with super-physiological flow rate, eventually enlarges the vein and creates a "mature" and effective vascular access 2-4 months after surgery. Mature vascular access can achieve sufficient blood flow rate, effective dialysis surgery, and adaptability to cannulation or large needles.

[0005] Related reports show that 39% of AVFs placed between June 2014 and May 2016 failed to mature (i.e., primary failure) and were never used for dialysis treatment; of those mature AVFs, 40% required intervention and 29% of patients abandoned within 1 year. The primary failure rate of AVG is 19%, and the primary and secondary patency rates after 1 year are 30-50% and 55-70%, respectively; the failure rate of saphenous vein grafts for coronary artery bypass grafting (CABG) is 10-20% within 1 year, and the failure rate is as high as 50% within 10 years; the failure rate of peripheral artery bypass grafts (PABGs) is 30-50% within 5 years. The 5-year hemodialysis survival rate caused by AVF and AVG failure is only 42%, and the 30-day ESRD readmission rate is 34.2%. The Centers for Medicare and Medicaid Services incurs $2-3 billion in costs each year to treat these dysfunctions.

[0006] The main cause of primary failure of AVF is considered to be the stenosis of the para-anastomotic venous segment, which is mainly related to intimal hyperplasia, mainly caused by turbulence generated at the anastomosis. Many studies have pointed out that the geometric characteristics of the anastomosis determine the hemodynamic pattern of AVF. On the one hand, the hemodynamic stress in the low shear stress and turbulent flow area near the fistula, the blood flow and wall pressure near the venous anastomosis increase, causing vascular smooth muscle cells and muscle fibers in the venous wall to migrate to the intima, and deposit extracellular matrix proteins to form a "new intima", which hinders blood from passing through the channel; on the other hand, the venous blood pressure is low and the wall is thin, and the vein is subjected to high tube wall tension after "arterialization", so the venous wall thickens in an attempt to reduce the sudden high tube wall tension.

[0007] Typically, AVFs are created as distally as possible, starting from the radial artery at the wrist (RCAVF) when possible. The maturation rate of RCAVF still has room for improvement. In an analysis of 12 studies including 1,447 AVFs, the primary failure rate of lower arm AVFs was estimated to be 28%, with a 95% confidence interval of 20% to 37%. Similarly, excluding primary failure, the primary patency loss rate of lower arm AVFs was estimated to be 38%. These patients with AVF failures need to undergo re-stenosis. After the re-stenosis matures, there is also a possibility of restenosis at the fistula during dialysis. Restenosis may cause blockage of the fistula and ultimately make dialysis impossible.

[0008] So far, there is no effective method to improve the maturity and patency of fistulas.

[0009] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0010] The main purpose of the present invention is to provide a degradable extravascular stent and a system and control method thereof, aiming to solve the above-mentioned problems.

[0011] In order to achieve the above object, the present invention provides a degradable extravascular stent system, comprising:

[0012] A main stent covering the arterial end, wherein the material density of the main stent is 50-300 mg / cm 3 ;

[0013] A side sleeve covering the venous end, the side sleeve is connected to the main stent, and the angle between the side sleeve and the main stent is adjustable, the angle adjustment range is 20-70°, the main stent and the side sleeve are in an open state with a complete circular shape along the extension direction of the tube wall, the main stent is covered on the arteriovenous fistula after adjusting the angle of the fistula during the operation, and the two sides of the opening are fixed with interlocking devices after the main stent is closed; the side sleeve and the main stent are made of biodegradable polymers, the main stent and the side sleeve are drug-loaded / drug-free, the elastic modulus of the biodegradable polymer is 100MPa-1000MPa, the diameter of the side sleeve is increased from the connection with the main stent to the direction away from the main stent, and the radial compliance is 2-30% / 100mmHg, and the material density of the side sleeve is 100-500mg / cm 3 , the length and density of the side sleeve are greater than those of the main stent, and the porosity of the main stent and the side sleeve is 20-95%; wherein the side sleeve and the main stent are multi-layered structures along the thickness direction, the side sleeve and the main stent are made of the same material with different molecular weights or different materials along the thickness direction, and the degradation time of the inner layer materials of the side sleeve and the main stent near the anastomosis is less than the degradation time of the remaining areas of the side sleeve and the main stent;

[0014] The controller is configured as:

[0015] After the artery and vein are anastomosed, the blood flow and inner diameter at different positions of the arterial end, the fistula anastomosis, and the venous outflow tract on the center line of the arteriovenous fistula are obtained;

[0016] According to the blood flow and inner diameter at different positions of the arterial end, internal fistula anastomosis, and venous outflow tract, the fluid simulation model is used for fitting;

[0017] Adjust the angle and radius of curvature of the arteriovenous anastomosis until the blood flow rate near the venous outflow tract is adjusted from turbulent flow and disturbed flow to laminar flow;

[0018] The angle at the anastomosis was taken as the target angle.

[0019] Preferably, in the degradable extravascular stent system, the side sleeve and the main stent are multi-layer structures in thickness direction, and when the side sleeve and the main stent are made of the same material but different molecular weight, the inner layer molecular weight of the side sleeve and the main stent near the anastomosis is smaller than the outer layer molecular weight.

[0020] Preferably, in the degradable extravascular stent system, the main stent has a closed state after covering the anastomosis, and the main stent in the closed state has a length L of 10mm-40mm, an outer diameter of 3-10mm, and a wall thickness of 0.1-1mm.

[0021] Preferably, in the degradable extravascular stent system, the side sleeve has a length of 10-60 mm, a small diameter of 2.5-6 mm, a large diameter of 4-10 mm, and a wall thickness of 0.1-1 mm.

[0022] Preferably, in the degradable extravascular stent system, the surface of the biodegradable polymer or the material thereof is mixed with drugs, the drug loading is 0.2 ug-100 mg / mg, and the drug release duration is 7 days-30 days.

[0023] Preferably, in the degradable extravascular stent system, the drug loaded is paclitaxel, rapamycin, cyclosporine, methotrexate, heparin, dexamethasone, tetracycline, or everolimus.

[0024] Preferably, in the degradable extravascular stent system, the biodegradable polymer is a copolymer or blend of one or more of polylactic acid, polycaprolactone, polyhydroxybutyrate, polyglycerol sebacate, polyvinyl alcohol, polybutylene succinate, poly-α-acrylate, polyglycolic acid, polylactic acid / glycolic acid copolymer, polyglycolic acid, collagen, cellulose, and chitosan.

[0025] Preferably, in the degradable extravascular stent system, the collagen is collagen made from type I, II, III, IV, VI collagen and a mixture thereof.

[0026] Preferably, in the biodegradable extravascular stent system, the biodegradable extravascular stent is prepared by a composite of one or more methods including weaving, solution building, injection molding, direct writing, and 3D printing.

[0027] Preferably, in the degradable extravascular stent system, the blood flow rate at the arteriovenous fistula is measured by combining one or more of nuclear magnetic resonance, ultrasound, optical coherence tomography (OCT), and electronic computed tomography (CT).

[0028] Preferably, in the degradable extravascular stent system, the degradation time of the degradable extravascular stent system in vivo is 3 months to 2 years.

[0029] In order to achieve the above object, the present invention also provides a degradable extravascular stent system, comprising:

[0030] The main stent that covers the arterial end;

[0031] A side sleeve covering the venous end, the side sleeve is connected to the main stent, and the angle between the side sleeve and the main stent is adjustable, the adjustment range of the angle is 20-70°, the side sleeve and the main stent are made of biodegradable polymers, the elastic modulus of the biodegradable polymer is 100MPa-1000MPa, the diameter of the side sleeve increases from the connection with the main stent to the direction away from the main stent, and the radial compliance is 2-30% / 100mmHg:

[0032] The controller is configured as:

[0033] After the artery and vein are anastomosed, controlling and adjusting the angle of the internal fistula anastomosis;

[0034] Obtain blood flow and inner diameter at different locations near the arterial end, anastomosis, and venous outflow tract on the center line of the arteriovenous fistula, with a collection time of more than 5 seconds;

[0035] According to the blood flow and inner diameter at different positions of the proximal arterial end, the anastomosis, and the proximal venous outflow tract, the blood flow rate at the anastomosis and the proximal venous outflow tract is adjusted;

[0036] When the blood flow rate is in a laminar flow state, the angle is used as a target angle.

[0037] In order to achieve the above object, the present invention further provides a degradable extravascular stent, comprising:

[0038] The main stent that covers the arterial end;

[0039] A side sleeve covering the venous end, the side sleeve is connected to the main stent, and the angle between the side sleeve and the main stent is adjustable, the adjustment range of the angle is 20-70°, the side sleeve and the main stent are both made of biodegradable polymers, the elastic modulus of the biodegradable polymer is 100MPa-1000MPa, the diameter of the side sleeve increases from the connection with the main stent to the direction away from the main stent, and the radial compliance is 2-30% / 100mmHg.

[0040] In order to achieve the above object, the present invention also provides a control method for a degradable extravascular stent, wherein the degradable extravascular stent comprises a main stent covering an arterial end and a side sleeve covering a venous end, and the control method comprises:

[0041] After the artery and vein are anastomosed, the blood flow and inner diameter at different positions of the proximal arterial end, the anastomosis, and the venous outflow tract on the center line of the arteriovenous fistula are obtained;

[0042] According to the blood flow and inner diameter at different locations near the arterial end, anastomosis, and near the venous outflow tract, a fluid simulation model was used for fitting;

[0043] The angle and radius of curvature of the arteriovenous anastomosis are adjusted until the blood flow velocity at the anastomosis and near the venous outflow tract is adjusted from turbulent flow and disturbed flow to laminar flow, and the angle at the anastomosis is used as the target angle.

[0044] In order to achieve the above object, the present invention also provides a control method of a degradable extravascular stent, which controls the above-mentioned degradable extravascular stent system and is used for fixing blood vessels at the anastomosis of arteriovenous fistula after arteriovenous fistula surgery.

[0045] The present invention has at least the following beneficial effects:

[0046] The degradable extravascular stent system provided by the present invention comprises a main stent covering the arterial end, a side sleeve covering the venous end, and a controller. The material density of the main stent is 50-300 mg / cm 3 ; The side sleeve is connected to the main stent, and the angle between the side sleeve and the main stent is adjustable, the adjustment range of the angle is 20-70°, the main stent and the side sleeve are in an open state with a complete circular shape along the extension direction of the tube wall, and the stent is covered on the arteriovenous fistula after adjusting the angle of the fistula during the operation. After the stent is closed, the two sides of the opening are fixed with interlocking devices; the side sleeve and the main stent are made of biodegradable polymers, the main stent and the side sleeve are drug-loaded / drug-free, the elastic modulus of the biodegradable polymer is 100MPa-1000MPa, the diameter of the side sleeve is increased from the connection with the main stent to the direction away from the main stent, and the radial compliance is 2-30% / 100mmHg, and the material density of the side sleeve is 100-500mg / cm 3 , the wire diameter and density of the side sleeve are greater than the wire diameter and density of the main stent; wherein the side sleeve and the main stent are multi-layered structures along the thickness direction, the side sleeve and the main stent are made of the same material but different molecular weight or different materials along the thickness direction, and the degradation time of the inner layer materials of the side sleeve and the main stent near the anastomosis is less than the degradation time of the other areas of the side sleeve and the main stent, the side sleeve and the main stent are made of biodegradable polymers, the elastic modulus of the biodegradable polymers is 100MPa-1000MPa, the diameter of the side sleeve increases from the connection with the main stent to the direction away from the main stent, and the radial compliance is 2-30% / 100mmHg, and the density is 100-500mg / cm 3, the wire diameter and density of the side sleeve are greater than the wire diameter and density of the main stent; wherein the side sleeve and the main stent are multi-layered structures along the thickness direction, the side sleeve and the main stent are made of the same material with different molecular weights or different materials along the thickness direction, and the degradation time of the inner layer materials of the side sleeve and the main stent near the anastomosis is less than the degradation time of the other areas of the side sleeve and the main stent, so as to reduce the blood flow turbulence at the anastomosis in the early stage of maturation of the arteriovenous fistula, adjust the angle between the artery and the vein, and reduce the deformation of the blood vessels at the anastomosis to achieve the effect of regulating blood flow;

[0047] Furthermore, the degradable extravascular stent provided by the present invention can limit the expansion of the tube wall extending from the anastomosis to the distal vein end, reduce the increased tube wall tension and stress borne by the vein end, and its shape can better cover the geometric shapes of the arteriovenous fistula anastomosis and the vein, and by adjusting the angle at the arteriovenous anastomosis, eliminate the thickening of the vein wall caused by excessive expansion of the tube wall after "arterialization" of the vein.

[0048] Furthermore, the degradable extravascular stent material provided by the present invention ensures sufficient mechanical support at the venous anastomosis in the first 3 months after surgery, and can be fully degraded within 1-2 years after surgery, while also reducing the risks of infection, chronic inflammation, vascular intimal hyperplasia, and compliance mismatch caused by long-term stent implantation. The degradable stent can adjust the porosity of the stent through the preparation process, promote and induce the formation of new blood vessels, and increase the success rate and patency rate after arteriovenous fistula. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A schematic diagram of an embodiment of a degradable extravascular stent provided by the present invention;

[0050] Figure 2 A schematic diagram of another embodiment of the degradable extravascular stent provided by the present invention;

[0051] Figure 3 A schematic diagram of a third embodiment of the degradable extravascular stent provided by the present invention;

[0052] Figure 4 It is a process of the control method of the degradable extravascular stent of the present invention;

[0053] Figure 5 This is another process of the control method of the degradable extravascular stent of the present invention;

[0054] Figure 6 A schematic diagram of a computer device provided by the present invention.

[0055] 1- side casing, 2- main support.

[0056] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0057] In the embodiments of the present invention, the term "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent three situations: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0058] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0059] In the embodiments of the present invention, the term "plurality" refers to two or more than two, and other quantifiers are similar.

[0060] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. However, it can be understood by those skilled in the art that in the embodiments of the present invention, many technical details are proposed in order to enable the reader to better understand the present invention. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present invention can also be implemented. The division of the following embodiments is for the convenience of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined and referenced with each other under the premise of no contradiction.

[0061] At present, the commonly used extravascular stents on the market are metal stents, which are non-degradable after implantation in the patient's body. If they are not removed by surgery, they will remain in the patient's body permanently. After the arteriovenous fistula matures, they will remain in the patient's body for a long time as a foreign body, increasing the patient's safety risk. In addition, the inner diameter of the metal stent lumen is fixed and cannot be adjusted according to the different stages of the patient's surgery. The compliance is not matched, which makes the lumen subject to high stress, leading to cell proliferation and migration in the lumen, reducing blood flow rate, and ultimately leading to vascular obstruction.

[0062] The present invention provides a degradable extravascular stent system. Figure 1 and Figure 2 The degradable extravascular stent system includes a degradable extravascular stent and a controller. The degradable extravascular stent includes a main stent 2 covering the arterial end and a side sleeve 1 covering the venous end.

[0063] The degradable extravascular stent is used for fixation at the anastomosis after arteriovenous fistula surgery. The material density of the main stent 2 is 50-300 mg / cm 3The wire diameter and density determine the degradation time of the material. When the wire diameter and density are too large, the stent degradation time is long. The polymer degradation changes the pH of the local tissue environment, and inflammation and infection are prone to occur near the anastomosis. When the wire diameter and density are too small, the stent degrades quickly and the intimal hyperplasia of the anastomosis may cause the fistula to fail to "mature", and the patient's hemodialysis access cannot be used for hemodialysis.

[0064] The main stent 2 can be, but is not limited to, closed, open or a combination of the two. The main stent 2 can also be sheet-like (covering the blood vessel part without hollowing out), woven, mesh-like, uninterrupted or regularly hollowed out.

[0065] The main stent 2 has a closed state after covering the anastomosis. The main stent 2 has a length L in the closed state, 10mm≤L≤40mm, an outer diameter of 3-10mm, and a wall thickness of 0.1-1mm. In actual use, the main stent 2 extends from the anastomosis. If the stent is too long, the excess length reduces the area where the blood vessel can be punctured for dialysis; if the main stent 2 is too short, the stent fixation effect is poor, and the expansion of the venous wall cannot be effectively controlled in the middle and late stages of implantation, reducing the long-term patency rate.

[0066] The side sleeve 1 is connected to the main support 2, and the angle between the side sleeve 1 and the main support 2 is adjustable, and the adjustment range of the angle is 20-70°. The side sleeve 1 and the main support 2 are made of biodegradable polymers, and the elastic modulus of the biodegradable polymer is 100MPa-1000MPa. Since the side sleeve 1 and the main support 2 are both made of biodegradable polymers with an elastic modulus of 100MPa-1000MPa, the doctor can adjust the angle between the side sleeve 1 and the main support 2 according to the needs of use, and the support at the anastomosis can be guaranteed; further, the deformation of the outer diameter of the blood vessel at the venous end can be reduced, thereby reducing the thickening of the venous wall at the anastomosis.

[0067] In some other embodiments, the angle adjustment range may vary depending on the choice of biodegradable polymer material, for example, the angle adjustment range may also be 30-50°, or 50-65°.

[0068] Furthermore, by adjusting the angle between the artery and vein at the anastomosis, the support of the anastomosis is increased and the deformation of the anastomosis caused by blood turbulence is reduced, while ensuring the convenience of the surgical operation, the influence of the high tube wall tension at the venous end on the anastomosis is effectively reduced.

[0069] The side sleeve 1 can be, but is not limited to, closed, open or a combination of the two. The side sleeve 1 can also be sheet-like (the part covering the blood vessel is not hollowed out), woven, mesh-like, uninterrupted or regularly hollowed out.

[0070] Compared with the side sleeve 1 and the main stent 2 that are all or partially made of alloy wire or non-degradable polymer wire, the present invention uses degradable materials to ensure support while avoiding the material from existing as a foreign body in the body, which may cause infection. The doctor may adjust the angle between the side sleeve and the main stent 2 according to the situation; in other embodiments, the angle that best suits the patient may be fitted according to the blood flow and blood vessel conditions at the patient's arteriovenous fistula based on the fluid simulation model, so that the blood flow can be adjusted to avoid unlimited expansion of the venous wall after anastomosis.

[0071] The venous blood pressure is low and the wall is thin. After arteriovenous fistula, the "arterialized" vein is subjected to high-pressure wall tension, and the venous wall thickens to try to reduce the sudden high-pressure wall tension. If the compliance of the stent venous segment is too small, the wall expansion is compressed, the blood flow rate is reduced, and the probability of thrombosis is increased; when the compliance of the stent is too large, the stent does not restrict and fix the wall, and the long-term patency rate increases. Therefore, the diameter of the side sleeve 1 increases from the connection with the main stent 2 to the direction away from the main stent 2, and the radial compliance is 2-30% / 100mmHg. The length of the side sleeve 1 is 10-60mm, the small diameter is 2.5-6mm, the large diameter is 4-10mm, and the wall thickness is 0.1-1mm.

[0072] The density of the side tube sleeve is 100-500 mg / cm 3 The wire diameter and density of the side sleeve are greater than the wire diameter and density of the main stent 2; further, the material density of the main stent 2 is 50-300 mg / cm 3 , which can prolong the shaping time of the anastomosis and the venous segment stent (i.e., side sleeve).

[0073] The side sleeve 1 and the main stent 2 are multi-layer structures along the thickness direction. The side sleeve 1 and the main stent 2 can be the same material with different molecular weights or different materials along the thickness direction, and the degradation time of the inner layer material of the side sleeve 1 and the main stent 2 near the anastomosis is less than the degradation time of the other areas of the side sleeve 1 and the main stent 2. When the side sleeve 1 and the main stent 2 are the same material with different molecular weights along the thickness direction, the inner layer molecular weight of the side sleeve 1 and the main stent 2 near the anastomosis is less than the outer layer molecular weight. When the side sleeve 1 and the main stent 2 are different materials along the thickness direction, the inner layer material of the side sleeve 1 and the main stent 2 near the anastomosis degrades faster. In this way, the anastomosis can be fixed in the short term after surgery, and as the anastomosis gradually matures, the stress of the degradable extravascular stent on the vein gradually decreases.

[0074] For example, the inner layer of the side sleeve 1 and the main stent 2 near the anastomosis degrades at a rate of 3 to 6 months, while the outer layer of the side sleeve 1 and the main stent 2 near the anastomosis degrades at a rate of 1 to 2 years.

[0075] In addition, the surface or material of the biodegradable polymer is mixed with drugs, such as paclitaxel and rapamycin. The degradation time of the degradable extravascular stent system in vivo is 3 months to 2 years.

[0076] The biodegradable polymer provided by the present invention may include, but is not limited to, one or more materials that meet the above elastic modulus conditions, including lactic acid, polycaprolactone, polyhydroxybutyrate, polyglycerol sebacate, polyvinyl alcohol, polybutylene succinate, poly-α-acrylate, polyglycolic acid, polylactic acid / glycolic acid copolymer, polyglycolic acid, collagen, cellulose, and chitosan. The degradable extravascular stent may be, but is not limited to, compositely prepared by one or more methods including direct writing, 3D printing, weaving, solution casting, and injection molding.

[0077] In a feasible usage scenario, the degradable extravascular stent at the anastomosis is used after the anastomosis of the autologous arteriovenous fistula to adjust the blood flow rate and wall pressure at the venous anastomosis, reduce the venous anastomosis to promote the formation of the vascular adventitia and block the outward remodeling of elastin, thereby improving the success rate after arteriovenous fistula.

[0078] In another feasible use scenario, the method for using the degradable extravascular stent at the anastomosis provided by the present invention is as follows: after the artery and vein are anastomosed during surgery, the blood flow rate at the arteriovenous fistula is measured by nuclear magnetic resonance, ultrasound, optical coherence tomography (OCT), and electronic computer tomography (CT). After finite element analysis, the optimal internal fistula angle is obtained, and the angle between the main stent 2 and the measuring sleeve is adjusted to this angle to meet the anastomosis of arteries and veins in different parts and sizes, and the operation is convenient during surgery. The degradable extravascular stent increases the support of the venous anastomosis and reduces the problem of compliance mismatch in the first 3 months after surgery. It can be fully degraded within 3 months to 2 years after surgery, and also reduces the risks of infection and chronic inflammation caused by long-term implantation of the stent, and increases the success rate after arteriovenous fistula.

[0079] Different patients and different arterial and venous anastomoses will have different corresponding situations. After being implanted in the patient's body, the extravascular stent needs to minimize the effects of hemodynamic wall tension and wall shear stress on the vascular anastomosis for a long time, and minimize the damage to the anastomosis caused by blood flow arterial pressure, wall tension, and shear stress. Therefore, it is very important to choose a more appropriate angle for different application scenarios.

[0080] Figure 4The process 1000 of the control method of the degradable extravascular stent of the present invention is shown. The process 1000 can be used Figure 1 The method is executed by the schematically shown degradable extravascular stent system, and specifically by a controller.

[0081] At step 1010, the blood flow and inner diameter at different positions are obtained. After the main stent 2 is anastomosed with the artery and the side sleeve 1 is fixed with the vein, the blood flow and inner diameter at different positions of the proximal arterial end, the anastomosis, and the venous outflow tract on the center line of the arteriovenous fistula are obtained. At least 3 points are measured at the proximal arterial end and at least 5 points are measured at the venous outflow tract, and the values ​​of each point are continuously read for 3 heartbeats; the venous outflow tract is set to a non-traction condition, the blood vessel wall is rigid, and the blood density is 1.05g / cm 3 The blood flow and inner diameter can be measured by using a sensor, as long as the sensor can measure the flow and the inner diameter.

[0082] At step 1020, a fluid simulation model is used for fitting. The fluid simulation model is used for fitting according to the blood flow and inner diameter at different positions near the arterial end, the anastomosis, and the venous outflow tract. The fluid simulation model can be, but is not limited to, a finite element analysis model.

[0083] At step 1030, the angle and the radius of curvature at the arteriovenous anastomosis are adjusted until the blood flow velocity at the anastomosis and near the venous outflow tract is adjusted from turbulent flow and disturbed flow to laminar flow.

[0084] The flow of blood in blood vessels can be divided into laminar flow and turbulence. Laminar flow is the regular flow of fluid with clear streamlines. In the case of laminar flow, the flow direction of each particle of the liquid is consistent and parallel to the long axis of the pipe, but the flow speed of each particle is different. The flow speed is fastest at the axis of the blood vessel, and the closer to the wall, the slower. The closer to the axis, the higher the blood cell concentration. Under normal circumstances, the flow of blood in blood vessels is in the form of laminar flow. However, when the blood flow speed increases to a certain extent, the normal laminar flow is destroyed, the flow direction of each particle in the blood is no longer consistent, vortices may appear, and turbulence is generated. Turbulence is an irregular flow state. At this time, the resistance of the pipe wall to the flow of liquid increases, and the energy consumed by the blood flow to overcome the resistance also increases significantly. Therefore, the blood flow rate will decrease under the same pressure difference.

[0085] During the fitting process, when the blood flow rate is in a laminar state, the angle at the anastomosis at this time can be used as the target angle.

[0086] After the target angle is determined, it can be displayed on a display screen or in other ways to prompt the doctor, so that the doctor can adjust the angle between the side sleeve 1 and the main support 2 according to the target angle.

[0087] Figure 5 Indicated Figure 3 The process 2000 of the control method of the degradable extravascular stent of the present invention is shown schematically. The process 2000 can be used Figure 1 The method is executed by the schematically shown degradable extravascular stent system, and specifically by a controller.

[0088] At step 2010, the angle is controlled and adjusted. After the main stent 2 is anastomosed with the artery and the side sleeve 1 is anastomosed with the vein, the angle can be adjusted by the doctor in the patient's body or by fitting using a fluid simulation model.

[0089] At step 220, the blood flow and inner diameter at different locations are obtained in real time. The blood flow and inner diameter at different locations near the arterial end, the anastomosis, and the venous outflow tract on the center line of the arteriovenous fistula are obtained in real time. At least 3 points near the arterial end and at least 5 points in the venous outflow tract are measured, and the value of each point is continuously read for 3 heartbeats; the venous outflow tract is set to a non-traction condition, the vascular wall is rigid, and the blood density is 1.05g / cm 3 The blood flow and inner diameter can be measured by using a sensor, as long as the sensor can measure the flow and the inner diameter.

[0090] At step 2030, the blood flow rate of the anastomosis and the proximal venous outflow tract is determined. The blood flow rate of the anastomosis and the proximal venous outflow tract is determined based on the blood flow rate and inner diameter of different positions of the proximal arterial end, the anastomosis, and the proximal venous outflow tract. When the blood flow rate and inner diameter of different positions are known, the blood flow rate can be calculated.

[0091] At step 2040, when the blood flow velocity is in a laminar state, the angle is used as the target angle. In other ways, a mapping method can also be used to establish a corresponding relationship between the blood flow velocity and the corresponding target angle, and the target angle can be found according to the blood flow velocity.

[0092] In order to achieve the above object, the present invention also provides a computer device, such as Figure 6 As shown, the computer device includes at least one processor 201; and a memory 202 that is communicatively connected to the at least one processor 201; wherein the memory 202 stores instructions that can be executed by the at least one processor 201, and the instructions are executed by the at least one processor 201 so that the at least one processor 201 can execute the above-mentioned control method of the degradable extravascular stent.

[0093] The memory 202 and the processor 201 are connected in a bus manner, and the bus may include any number of interconnected buses and bridges, and the bus connects various circuits of one or more processors 201 and the memory 202 together. The bus can also connect various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be one element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices on a transmission medium. The data processed by the processor 201 is transmitted on a wireless medium through an antenna, and further, the antenna also receives data and transmits the data to the processor 201.

[0094] The processor 201 is responsible for managing the bus and general processing, and can also provide various functions, including timing, peripheral interfaces, voltage regulation, power management and other control functions. The memory 202 can be used to store data used by the processor 201 when performing operations.

[0095] In order to achieve the above object, the present invention provides a computer-readable storage medium storing a computer program, wherein the computer program implements the control method of the above-mentioned degradable extravascular stent when executed by a processor.

[0096] That is, those skilled in the art can understand that all or part of the steps in the above-mentioned implementation method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including several instructions to enable a device (which can be a single-chip microcomputer, chip, etc.) or a processor to execute all or part of the steps of the method described in each implementation of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0097] Obviously, the embodiments described above are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, ordinary technicians in this field can make other different forms of changes or modifications without creative work, which should fall within the scope of protection of the present invention.

Claims

1. A degradable extravascular stent system, characterized in that: include: A main stent covering the arterial end, wherein the material density of the main stent is 50-300 mg / cm 3 ; A side sleeve covering the venous end, the side sleeve is connected to the main stent, and the angle between the side sleeve and the main stent is adjustable, the adjustment range of the angle is 20-70°, the main stent and the side sleeve are in an open state with a complete circular shape along the extension direction of the tube wall, the main stent is covered on the arteriovenous fistula after adjusting the angle of the fistula during the operation, and the two sides of the opening are fixed with interlocking devices after the main stent is closed; the side sleeve and the main stent are made of biodegradable polymers, the main stent and the side sleeve are drug-loaded / drug-free, the elastic modulus of the biodegradable polymer is 100MPa-1000MPa, the diameter of the side sleeve is increased from the connection with the main stent to the direction away from the main stent, and the radial compliance is 2-30% / 100mmHg, and the material density of the side sleeve is 100-500mg / cm 3 , the length and density of the side sleeve are greater than those of the main stent, and the porosity of the main stent and the side sleeve is 20-95%; wherein the side sleeve and the main stent are multi-layered structures along the thickness direction, the side sleeve and the main stent are made of the same material with different molecular weights or different materials along the thickness direction, and the degradation time of the inner layer materials of the side sleeve and the main stent near the anastomosis is less than the degradation time of the remaining areas of the side sleeve and the main stent; The controller is configured as: After the artery and vein are anastomosed, the blood flow and inner diameter at different positions of the arterial end, the fistula anastomosis, and the venous outflow tract on the center line of the arteriovenous fistula are obtained; According to the blood flow and inner diameter at different positions of the arterial end, internal fistula anastomosis, and venous outflow tract, the fluid simulation model is used for fitting; Adjust the angle and radius of curvature of the arteriovenous anastomosis until the blood flow rate near the venous outflow tract is adjusted from turbulent flow and disturbed flow to laminar flow; The angle at the anastomosis was taken as the target angle.

2. The degradable extravascular stent system according to claim 1, characterized in that: The side sleeve and the main stent are multi-layer structures in thickness direction. When the side sleeve and the main stent are made of the same material but different molecular weights, the inner layer molecular weight of the side sleeve and the main stent near the anastomosis is smaller than the outer layer molecular weight.

3. The degradable extravascular stent system according to claim 1, characterized in that: The main stent has a closed state after covering the anastomotic stoma. The main stent in the closed state has a length L of 10 mm-40 mm, an outer diameter of 3-10 mm, and a wall thickness of 0.1-1 mm.

4. The degradable extravascular stent system according to claim 1, characterized in that: The side sleeve has a length of 10-60 mm, a small diameter of 2.5-6 mm, a large diameter of 4-10 mm, and a wall thickness of 0.1-1 mm.

5. The degradable extravascular stent system according to claim 1, characterized in that: The surface of the biodegradable polymer or the material thereof is mixed with drugs, the drug loading amount is 0.2ug-100mg / mg, and the drug release duration is 7 days-30 days.

6. The degradable extravascular stent system according to claim 5, characterized in that: The drug loading is paclitaxel, rapamycin, cyclosporine, methotrexate, heparin, dexamethasone, tetracycline, and everolimus.

7. The degradable extravascular stent system according to claim 1, characterized in that: The biodegradable polymer is a copolymer or blend of one or more of polylactic acid, polycaprolactone, polyhydroxybutyrate, polyglycerol sebacate, polyvinyl alcohol, polybutylene succinate, poly-α-acrylate, polyglycolic acid, polylactic acid / glycolic acid copolymer, polyglycolic acid, collagen, cellulose, and chitosan.

8. The degradable extravascular stent system according to claim 7, characterized in that: The collagen is collagen obtained from type I, II, III, IV, VI collagen and mixtures thereof.

9. The degradable extravascular stent system according to claim 1, characterized in that: The degradable extravascular stent system is prepared by compositely using one or more methods of weaving, solution building, injection molding, direct writing, and 3D printing.

10. The degradable extravascular stent system according to claim 1, characterized in that: The blood flow rate at the arteriovenous fistula site is measured by one or more of MRI, ultrasound, optical coherence tomography (OCT), and computed tomography (CT).

11. The degradable extravascular stent system according to claim 1, characterized in that: The biodegradable extravascular stent system has a degradation time in vivo of 3 months to 2 years.

12. A degradable extravascular stent system, characterized in that: include: The main stent that covers the arterial end; A side sleeve covering the venous end, the side sleeve is connected to the main stent, and the angle between the side sleeve and the main stent is adjustable, the adjustment range of the angle is 20-70°, the side sleeve and the main stent are made of biodegradable polymers, the elastic modulus of the biodegradable polymer is 100MPa-1000MPa, the diameter of the side sleeve increases from the connection with the main stent to the direction away from the main stent, and the radial compliance is 2-30% / 100mmHg: The controller is configured as: After the artery and vein are anastomosed, controlling and adjusting the angle of the internal fistula anastomosis; Obtain blood flow and inner diameter at different locations near the arterial end, anastomosis, and venous outflow tract on the center line of the arteriovenous fistula, with a collection time of more than 5 seconds; According to the blood flow and inner diameter at different positions of the proximal arterial end, the anastomosis, and the proximal venous outflow tract, the blood flow rate at the anastomosis and the proximal venous outflow tract is adjusted; When the blood flow rate is in a laminar flow state, the angle is used as a target angle.

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