Variable-flow type pressure-stabilizing covered stent

Abstract

A variable-flow type pressure-stabilizing covered stent comprises a stent body, the stent body comprises a bare stent, an inner-layer covering film and an outer-layer covering film, and the bare stent is wrapped between the inner-layer covering film and the outer-layer covering film; the high-molecular polymer is fixedly attached to the inner surface of the stent main body; wherein the high-molecular polymer is in a non-expansion state and can expand after entering blood vessels of a human body and encountering blood, and the diameter of an inner cavity of the expanded high-molecular polymer can change under the action of blood flow pressure, so that the blood flow is changed, and the blood pressure is stabilized.

Description

Technical Field

[0001] The invention patent relates to the field of medical devices, and in particular to a variable flow type voltage stabilizing coated stent. Background Art

[0002] Cirrhosis is a common disease in China. The decompensated stage often manifests as portal hypertension: repeated massive bleeding from esophageal and gastric varicose veins, and intractable pleural effusion and ascites, which seriously endanger the patient's life. In order to decompress the portal circulation, the portal vein is connected to the inferior vena cava through the hepatic vein, so that a transjugular intrahepatic portosystemic shunt (TIPS) can be formed through the liver tissue. TIPS has the characteristics of less trauma, fewer complications, and safety. It is an effective method for treating PHT, especially for patients with upper gastrointestinal bleeding caused by esophageal and gastric varicose veins, and its clinical efficacy has also been confirmed.

[0003] The TIPS covered stent is a commonly used vascular stent in TIPS surgery. It can connect the portal vein and the inferior vena cava, thereby reducing portal vein pressure. However, after the stent has been placed in the expected position for a period of time, the vascular pressure may change and fail to reach the expected value. Therefore, CN109069257B proposes a TIPS covered stent with adjustable diameter. After the stent is placed in the expected position, the doctor can adjust the diameter of the TIPS covered stent through a balloon catheter to adjust the vascular pressure. However, this adjustment requires the doctor to intervene again, increasing the risk of treatment. Summary of the invention

[0004] The purpose of the present invention is to overcome the above shortcomings and provide a double-layer pressure-stabilizing stent graft. The technical solution adopted by the present invention is as follows:

[0005] A variable flow and pressure-stabilizing coated stent comprises: a stent body, the stent body comprising a bare stent, an inner coating and an outer coating, the bare stent being wrapped between the inner coating and the outer coating; and a high molecular polymer, the high molecular polymer being fixedly attached to the inner surface of the stent body; wherein the high molecular polymer is in a non-expanded state and will expand upon entering a human blood vessel and encountering blood, and the inner cavity diameter of the expanded high molecular polymer will change under the action of blood flow pressure, thereby changing the blood flow size and stabilizing blood pressure.

[0006] Preferably, the expanded high molecular polymer has elasticity.

[0007] Preferably, the high molecular weight polymer is a hydrogel polymer.

[0008] Preferably, the hydrogel polymer comprises at least one of poly(hydroxyethyl methacrylate) (p-HEMA), poly(vinyl pyrrolidone) (PVP), poly(acrylamide) (pAM) and poly(acrylic acid) (pAA).

[0009] Preferably, the high molecular polymer is fixed to the inner surface of the stent body by sutures.

[0010] Preferably, the stent body includes a coated section and a non-coated section.

[0011] Preferably, the high molecular polymer is fixedly attached to the inner surface of the coating section.

[0012] Preferably, the inner layer coating and the outer layer coating are made of polymer materials.

[0013] Preferably, the polymer material is at least one of ePTFE (expanded polytetrafluoroethylene), PTFE (polytetrafluoroethylene), PE (polyethylene), FEP (perfluoroethylene propylene copolymer), and PU (polyurethane).

[0014] Preferably, the inner coating layer and the outer coating layer are bonded together by heat treatment.

[0015] Preferably, the height of the high molecular weight polymer changes when the blood vessel pressure is greater than 15 mmHg.

[0016] Preferably, the height variation rate of the high molecular polymer is 0-50%. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Variable flow and pressure-stabilizing covered stent in blood flow

[0018] Figure 2 In vitro variable flow and voltage-stabilizing covered stent

[0019] Figure 3 Appearance of variable flow type voltage stabilizing coated stent

[0020] Figure 4 Cross-section of variable flow voltage stabilizing coated stent DETAILED DESCRIPTION

[0021] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, further explanation is given below with reference to specific diagrams.

[0022] A variable flow stabilizing coated stent 100 comprises: a stent body 110, the stent body comprising a bare stent 111, an inner coating 112 and an outer coating 113, the inner coating 112 and the outer coating 113 wrap the bare stent 111 between them, wherein the stent body is divided into a coated section and a non-coated section, the coated section of the stent body is wrapped with inner and outer coatings, and the non-coated section has only a bare stent, such as Figure 3As shown in the figure, during the operation, the covered segment is located in the liver parenchyma to provide support to form a cavity for blood flow, so that the portal vein and the inferior vena cava can be connected, relieving the pressure of the gastric fundus vein. The bare segment is located in the inferior vena cava, which can effectively reduce the probability of stent capping. There are also imaging points at both ends of the stent to assist in the positioning of the stent in the blood vessel.

[0023] And, the polymer 120 is fixedly attached to the inner surface of the stent body 110; wherein the polymer 120 is in a non-expanded state, and will expand after entering into human blood vessels and encountering blood, and the inner diameter of the expanded polymer will change under the action of blood flow pressure, thereby changing the blood flow size and stabilizing blood pressure.

[0024] The expanded high molecular polymer has elasticity, so the shape of the high molecular polymer will change under the action of blood pressure.

[0025] In the existing pressure-adjustable TIPS covered stent, as described in CN109069257B, doctors need to use balloon catheters to expand the stent. If the patient is in poor condition after a period of time after the operation, the doctor needs to intervene again to expand the stent to adjust the blood vessel pressure. For example, the diameter of the middle section of the TIPS covered stent is 8mm and the two ends are 10mm. When the blood vessel pressure after the operation does not meet expectations, the doctor needs to use a balloon to expand the 8mm section of the stent to 9mm or even 10mm to reduce the blood vessel pressure.

[0026] In the present invention, an elastic polymer is arranged in the inner cavity of the stent. The polymer is compressed or expanded under the action of blood pressure, thereby changing the diameter of the inner cavity of the stent. The change of the inner cavity diameter will change the blood flow, thereby changing the blood pressure. For example, when the blood pressure increases, the pressure exerted by the blood on the polymer increases. At this time, the polymer is compressed, the inner cavity of the stent becomes larger, and the blood flow channel is increased, thereby releasing or reducing the blood pressure. When the blood pressure decreases, the pressure exerted by the blood on the polymer decreases, the polymer will rebound, the inner cavity of the stent will decrease, and the blood pressure will increase again to the previous level. The diameter of the inner cavity of the stent is adjusted through the above process to maintain the blood pressure at a reasonable level.

[0027] The high molecular polymer is a hydrogel polymer, which is fixed to the inner surface of the stent body by sutures. When in vitro, the hydrogel is in a non-expanded state, such as Figure 2As shown, this facilitates the transportation of the stent. When the stent enters the blood, the hydrogel will swell under the action of the blood and play a role in regulating blood flow. The hydrogel polymer includes at least one of poly(hydroxyethyl methacrylate) (p-HEMA), poly(vinyl pyrrolidone) (PVP), poly(acrylamide) (pAM) and poly(acrylic acid) (pAA).

[0028] The hydrogel polymer is also mixed with at least one of anti-proliferative substances such as heparin, rapamycin, paclitaxel, etc. to prevent the occurrence of restenosis in the stent.

[0029] The inner layer coating and the outer layer coating are made of polymer materials, which are at least one of ePTFE (expanded polytetrafluoroethylene), PTFE (polytetrafluoroethylene), PE (polyethylene), FEP (perfluoroethylene propylene copolymer), and PU (polyurethane).

[0030] The outer layer membrane is a double-layer structure, wherein ePTFE (expanded polytetrafluoroethylene) is used as the surface material, and low-melting-point polymer materials such as PE (polyethylene), FEP (perfluoroethylene propylene copolymer) or PU (polyurethane) are used as the bottom layer material. ePTFE (expanded polytetrafluoroethylene) is made of PTFE (polytetrafluoroethylene) through special processing methods such as stretching, is elastic and flexible, and has a mesh structure formed by connecting fine fibers, and these fine fibers form countless porous structures. PE (polyethylene), FEP (perfluoroethylene propylene copolymer) or PU (polyurethane) have a lower melting point than ePTFE (expanded polytetrafluoroethylene), so the above-mentioned bottom layer material and the surface layer material can be superimposed together and then heated to a certain temperature. At this temperature, the bottom layer material melts, while ePTFE (expanded polytetrafluoroethylene) does not melt. At this time, the melted bottom layer material will penetrate into the porous structure of ePTFE, and after cooling, the outer layer coating is formed. The inner layer coating is made of ePTFE (expanded polytetrafluoroethylene) and is also subjected to heat treatment. The inner layer coating and the outer layer coating are bonded together, and the bare stent is sandwiched between the inner and outer layer coatings.

[0031] The bare stent is made of woven metal wires. First, the metal wires are fixed into a certain shape through a mold, and the shape is spiral as a whole and S-shaped in part, such as Figure 3 As shown, the metal wire is then heat treated to form a desired shape. At this time, an oxide layer is formed on the surface of the bare stent due to the heat treatment, which may increase the risk of thrombosis, so polishing is required to make the surface of the bare stent shiny. After the bare stent is sleeved on the tubular membrane, the bare stent needs to be adjusted so that the bare stent fits on the surface of the tubular membrane.

[0032] The material of the metal wire is nickel-titanium alloy. Because the nickel-titanium alloy material has superelasticity, it can expand to its original shape after being compressed, so that it can provide excellent radial support force in the blood vessel, so that the stent fits the blood vessel. In another embodiment, the filamentous material of the bare stent is other metal materials, such as stainless steel, L605 steel, polymer, MP35N steel, stainless steel, polymer material, cobalt, chromium, nickel alloy, or polymer material, such as polyethylene terephthalate (PET) or polytetrafluoroethylene (PTFE), or biodegradable material, such as polylactic acid-glycolic acid copolymer (PLGA) or polylactic acid (PLA), or a combination of the above materials. During the processing, the wire can also be fixed into a certain shape using a mold first, and then heat-treated to set the shape.

[0033] The radial support force of the stent is mainly affected by the structure of the bare stent. The metal bare stent is a wavy structure. The height and spacing of the waves affect the radial support force of the stent. The higher the height of the waves and the smaller the spacing, the smaller the support force of the stent and the worse the flexibility; the lower the height of the waves and the larger the spacing, the greater the support force of the stent and the better the flexibility. The diameter of the nickel-titanium wire of the braided bare stent will also affect the mechanical properties of the stent. The larger the diameter, the greater the support force of the stent and the worse the flexibility. Preferably, the diameter of the nickel-titanium wire is between 0.15mm-0.3mm. The spacing, height and wire diameter of the bare stent waves are evenly distributed so that the radial support force of each section of the stent is the same. The above parameters can also be adjusted according to the indications so that the stent provides non-uniform radial force.

[0034] The bare stent is an integrated spiral cylindrical structure, and the spacing between each circle is the same so that the stent as a whole provides uniform radial force. In another embodiment, the distance between each circle is different, so that the stent at the lesion site is denser and the support force is stronger to open the cavity, while the stent at the normal blood vessel site is sparse to prevent the stent support force from being too large and damaging the blood vessel.

[0035] The described embodiments are to be considered in all respects as illustrative only and not restrictive. Therefore, the scope of the present disclosure is indicated by the appended claims rather than by the preceding description. All changes within the equivalent meaning and scope of the claims are included within their scope. The present invention is not limited to the above-described embodiments, which does not mean that the present invention must rely on the above-described embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims

1. A variable flow type voltage stabilizing stent graft, comprising: A stent body, the stent body comprising a bare stent, an inner layer coating and an outer layer coating, wherein the bare stent is wrapped between the inner layer coating and the outer layer coating; as well as, A high molecular polymer, wherein the high molecular polymer is fixedly attached to the inner surface of the stent body; The high molecular polymer is in a non-expanded state and will expand after entering human blood vessels and encountering blood. The inner diameter of the expanded high molecular polymer will change under the action of blood flow pressure, thereby changing the blood flow size and stabilizing blood pressure.

2. The variable flow type voltage stabilizing stent graft according to claim 1, characterized in that: The expanded high molecular polymer has elasticity.

3. The variable flow type voltage stabilizing stent graft according to claim 1, characterized in that: The high molecular polymer is a hydrogel polymer.

4. The variable flow type voltage stabilizing stent graft according to claim 1, characterized in that: The high molecular polymer is fixed to the inner surface of the stent body by suturing.

5. The variable flow type voltage stabilizing stent graft according to claim 1, characterized in that: The stent body includes a coated section and a non-coated section.

6. The variable flow type voltage stabilizing stent graft according to claim 1, characterized in that: The high molecular polymer is fixedly attached to the inner surface of the coating section.

7. The variable flow type voltage stabilizing stent graft according to claim 1, characterized in that: The inner layer coating and the outer layer coating are made of polymer materials.

8. The variable flow type voltage stabilizing stent graft according to claim 1, characterized in that: The inner layer film and the outer layer film are bonded together by heat treatment.

9. The variable flow type voltage stabilizing stent graft according to claim 1, characterized in that: The height of the high molecular weight polymer changes when the blood vessel pressure is greater than 15 mmHg.

10. The variable flow type voltage stabilizing stent graft according to claim 1, characterized in that: The height variation rate of the high molecular polymer is 0-50%.

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