Venous stent with high compliance

Abstract

The utility model relates to a kind of vein stents with high compliance, distal end braided stent is formed by wire with coating weaving, with high compliance, stent expanded diameter is slightly larger than target vein pipe diameter but smaller than proximal end laser engraved stent;Distal end braided stent includes wire, and coating located outside wire, coating is divided into inside coating and outside coating, inside coating curvature ratio is greater than outside coating, the surface roughness of inside coating is smaller than outside coating;A group of metal connecting short rod is connected by welding proximal end laser engraved stent and braided stent two parts.This stent has different structure and mechanical characteristics in different anatomical and kinematic characteristics vein segments, better adaptability, can better meet the needs of non-thrombotic iliofemoral vein stenosis occlusive disease patient iliofemoral vein stent implantation in stent fixation, cross joint placement stent.

Description

Technical Field

[0001] This utility model relates to a venous stent, and more particularly to a venous stent with high flexibility, belonging to the field of vascular stent technology. Background Technology

[0002] Nonthrombotic iliofemoral vein stenosis and occlusive disease is one of the most common and important diseases in vascular surgery. It has a high prevalence, imposes a significant medical and labor burden, and significantly affects patients' limb function and quality of life. With the advancement of endovascular treatment methods, percutaneous iliofemoral vein stenting has gradually replaced traditional open bypass surgery, becoming an important means of clinical treatment for deep vein diseases. It has advantages such as minimal invasiveness, rapid recovery, short operation time, and a patency rate far higher than that of open bypass surgery.

[0003] However, there are still many shortcomings in the venous stents currently used in clinical practice. The medical market currently uses laser-engraved stents and braided stents. For laser-engraved stents, the entire stent has uniform compressive strength, often resulting in stent collapse at compressed areas while lacking flexibility in uncompressed areas. Furthermore, the stent is prone to angulation at bends in the iliac vein, potentially increasing damage to the intima, causing intimal hyperplasia, and thrombosis recurrence. For braided stents, the stent has better flexibility and causes less damage to the vessel wall, but insufficient radial support can lead to complications such as stent migration. Utility Model Content

[0004] The purpose of this invention is to provide an asymmetric venous stent with increased friction in the anchoring zone, which ensures that the stent does not affect the blood flow of the contralateral vein at the biiliac junction, strengthens radial support at the proximal end of the iliac vein, exhibits strong compliance across the joint segment, and has high compliance and strong friction in the distal anchoring zone.

[0005] The present invention adopts the following technical solution:

[0006] A highly flexible venous stent comprises three stent components and a set of metal connecting rods 5. The three stent components, from proximal to distal, are: a proximal stent 1, a high radial support stent 2, and a distal braided stent 4, connected sequentially. The proximal stent 1 is positioned at the biiliac confluence of the iliac veins; the high radial support stent 2 is positioned at the easily compressed segment of the common iliac vein; and the distal braided stent 4 is positioned at the distal end of the common iliac vein and the external iliac vein. The radial support of the three stent components decreases in the following order: proximal stent 1 > high radial support stent 2 > distal braided stent 4. The flexibility of the three stent components decreases in the following order: The distal braided stent 4 > the strong radial support stent 2 > the proximal stent 1; the distal braided stent 4 is formed by braiding coated metal wires, and the stent expansion diameter is slightly larger than the target vein diameter but smaller than the strong radial support stent 2; the distal braided stent 4 includes a metal wire 401 and a coating located outside the metal wire 401. The coating is divided into an inner coating 402 and an outer coating 403. The inner coating has a larger arc ratio than the outer coating 403, and the surface roughness of the inner coating 402 is smaller than that of the outer coating 403; a set of metal connecting short rods 5 connect the laser-engraved stent 2 and the braided stent 4 by laser welding.

[0007] Preferably, the proximal end of the proximal support 1 is in the shape of a petal that opens slightly outward.

[0008] Preferably, the proximal support 1 is an open-design bare metal support manufactured using laser engraving technology; the material includes, but is not limited to, stainless steel, cobalt-chromium alloy, platinum-chromium alloy, and magnesium alloy.

[0009] Furthermore, the strong radial support stent 2 is a bare metal stent manufactured using laser engraving technology. The stent expansion diameter is larger than the target vein diameter, the metal wall thickness and metal coverage are larger than those of the proximal stent 1, and the length is 2-4 cm.

[0010] Furthermore, the density of the metal wire 401 is lower than that of the strong radial support force bracket 2, and the expansion diameter of the bracket is smaller than that of the strong radial support force bracket 2.

[0011] Furthermore, the coating is a polymer coating, and the coating material is polylactic acid-glycolic acid copolymer (PLGA). The outer coating 403, which is in contact with the blood vessel wall, has a surface roughness of about 0.8-1.2 μm, and the inner coating 402 has a surface roughness of less than 50 nm.

[0012] Furthermore, the distal braided stent 4 is 4-6cm long and covers the iliac vein across the joint.

[0013] Preferably, the curvature of the inner coating 402 is in the range of 240°-270°, and the remaining part is the curvature range of the outer coating 403.

[0014] Furthermore, the inner coating 402 and the outer coating 403 have the same thickness.

[0015] The beneficial effects of this utility model are as follows:

[0016] 1) This stent has different structural and mechanical characteristics in different anatomical and biomechanical segments of the vein, and has better targeted adaptability. It can better meet the needs of patients with non-thrombotic iliofemoral vein stenosis and occlusive disease for stent fixation and cross-joint placement during iliofemoral vein stent implantation.

[0017] 2) It can ensure that the stent does not affect the blood flow of the contralateral vein at the biiliac junction (the metal density of the proximal stent is low and the design is petal-shaped), the radial support of the proximal iliac vein is strengthened (the design of the strong radial support stent), and the distal anchoring area has high flexibility and strong friction (the design of the two-part coating of the distal braided stent). Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the highly flexible venous stent of this utility model.

[0019] Figure 2 yes Figure 1 A magnified cross-sectional view of the metal wires in the distal braided stent.

[0020] Figure 3 This is a schematic diagram of the highly flexible venous stent of this invention after it has been implanted into a human blood vessel.

[0021] Figure 4 This is a schematic diagram showing the connection between the strong radial support bracket and the distal braided bracket via a short rod.

[0022] In the figure, 1. Proximal support, 2. Strong radial support support, 4. Distal braided support, 401. Metal wire, 402. Inner coating, 403. Outer coating, 5. Short rod. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] This invention continues to possess the features that an ideal venous stent should have:

[0025] 1. Blood flow must be ensured at the confluence of the two iliac veins, and stent implantation should not affect blood flow in the contralateral vein;

[0026] 2. The stent in the proximal iliac vein anchorage zone requires strong radial support;

[0027] 3. Stents for veins spanning joint segments require high flexibility;

[0028] 4. The stent in the distal anchoring zone of the external iliac vein needs to maintain high flexibility and increase friction to ensure the stability of the distal anchoring zone.

[0029] Therefore, designing and fabricating asymmetrical stents that do not affect contralateral venous blood flow at the confluence of the two iliac veins, provide strong radial support to the proximal iliac vein, exhibit strong compliance across the joint segment, and possess high compliance and strong friction in the distal anchoring zone are of great significance for venous reconstruction in patients with nonthrombotic iliofemoral vein stenosis and occlusive diseases.

[0030] To address the shortcomings of current venous stents, this embodiment provides an asymmetric stent, comprising: an open-design stent at the confluence of the two iliac veins; a laser-engraved stent with strong radial support in the proximal anchoring zone of the iliac veins; and a highly flexible braided stent spanning joint segments with a high-friction coating on the metal braids. This design ensures that the stent does not affect contralateral venous blood flow at the confluence of the two iliac veins, provides strong radial support in the proximal iliac veins, and exhibits high flexibility and strong friction in the joint segments and distal anchoring zones.

[0031] See Figure 1-2 A highly flexible venous stent comprises three stent parts and a set of metal connecting rods 5. The three stent parts, from proximal to distal, are: a proximal stent 1, a strong radial support stent 2, and a distal braided stent 4, connected sequentially. The proximal stent 1 is positioned at the biiliac confluence of the iliac veins; the strong radial support stent 2 is positioned at the easily compressed segment of the common iliac vein; and the distal braided stent 4 is positioned at the distal end of the common iliac vein and the external iliac vein. The radial support of the three stent parts decreases in the following order: proximal stent 1 > strong radial support stent 2 > distal braided stent 4. The flexibility of the three stent parts decreases in the following order: The distal braided stent 4 > the strong radial support stent 2 > the proximal stent 1; the distal braided stent 4 is formed by braiding coated metal wires, and the stent expansion diameter is slightly larger than the target vein diameter but smaller than the strong radial support stent 2; the distal braided stent 4 includes a metal wire 401 and a coating located outside the metal wire 401, the coating being divided into an inner coating 402 and an outer coating 403, the inner coating having a larger curvature ratio than the outer coating 403, and the surface roughness of the inner coating 402 being less than that of the outer coating 403; a set of metal connecting short rods 5 connect the laser-engraved stent 2 and the braided stent 4 by laser welding. See also Figure 1-2 :

[0032] Open-design stent at the bilateral iliac confluence 1: This includes, but is not limited to, open-design bare metal stents manufactured using laser engraving technology, with materials including but not limited to stainless steel, cobalt-chromium alloy, platinum-chromium alloy, and magnesium alloy. The stent has relatively large pores and low wire density; by increasing the stent pores and reducing the wire density, interference with blood flow is minimized. The proximal opening of the stent is slightly larger, petal-shaped, ensuring that when both iliac veins are implanted with this design, the stents at the bilateral iliac vein confluence are staggered, minimizing impact on bilateral blood flow. (The materials of other bare metal stent portions are the same as above.)

[0033] Strong radial support stent in the proximal anchoring zone: Stent 2: Including but not limited to bare metal stents manufactured using laser engraving technology, with a larger expansion diameter (greater than the target vein diameter), thicker metal walls, and denser metal distribution. The radial support force in the proximal anchoring zone is increased by utilizing the larger expansion diameter, thicker metal walls, and higher metal coverage. The length is 2-4 cm, covering venous segments of the iliac vein susceptible to compression by arteries and the spine.

[0034] Distal braided stent 4: Formed from coated metal wires, this stent has a low wire density and a small expansion diameter (slightly larger than the target vein diameter), resulting in high flexibility. A polymer coating is added to the bare stent, including but not limited to polylactic-coated glycolic acid (PLGA). The coating surface in contact with blood has a low roughness (less than 50nm) and high smoothness, preventing platelets and blood cells from adhering inside the stent and causing in-stent thrombosis. The coating surface in contact with the vessel wall has a high roughness (approximately 1μm), which facilitates cell adhesion. This increases friction in the distal anchoring area, promoting a tighter bond between the implant and the vessel wall, thus improving stent fixation. It is 4-6cm long, covering the iliac vein across the joint. Metal connecting rod 5: Connects the laser-engraved stent 2 and braided stent 4 via laser welding. The shape of rod 5 can be curved, such as... Figure 4 As shown, it can also be a straight line (not shown in the attached diagram). See further details. Figure 2 :

[0035] The metal wire 401 of the braided bracket 4 in the distal anchoring area of ​​the bracket is made of materials including, but not limited to, stainless steel, cobalt-chromium alloy, platinum-chromium alloy, magnesium alloy, etc.

[0036] The braided stent 4 in the distal anchoring area has an inner coating 402. This coating material includes, but is not limited to, polylactic acid-glycolic acid copolymer (PLGA). The surface roughness (less than 50 nm) and smoothness of the coating in contact with blood are low, preventing platelets and blood cells from adhering inside the stent and causing in-stent thrombosis.

[0037] The braided stent 4 in the distal anchoring area of ​​the stent has an outer coating 403. The coating material includes, but is not limited to, polylactic acid-glycolic acid copolymer (PLGA). The surface roughness of the part of the coating that contacts the blood vessel wall is large (about 1 μm) and relatively rough, which is conducive to cell adhesion. By increasing the friction and promoting the tight bonding between the implant and the blood vessel wall, the friction of the distal anchoring area of ​​the stent is increased, which is conducive to stent fixation.

[0038] For specific stent implantation procedures, please refer to [reference needed]. Figure 3 :

[0039] An open-design stent 1 is used at the biiliac junction, which is inserted into the inferior vena cava during implantation.

[0040] The strong radial support stent 2 in the proximal anchoring zone is anchored to the proximal end of the iliac vein, with a length of 2-4 cm, covering the venous segment of the iliac vein that is susceptible to compression by arteries and the spine.

[0041] The braided stent 4 in the distal anchoring area is highly flexible, 4-6cm in length, covers the main lesion area including the iliac vein crossing the joint segment, is anchored to the external iliac vein, and has high flexibility and strong friction.

[0042] This stent has different structures and mechanical characteristics in venous segments with different anatomical and biomechanical features, which can meet the needs of stent fixation and cross-joint placement during iliofemoral vein stent implantation in patients with non-thrombotic iliofemoral vein stenosis and occlusive diseases.

[0043] The above are preferred embodiments of the present utility model. Those skilled in the art can make various changes or improvements based on this. Without departing from the overall concept of the present utility model, these changes or improvements should all fall within the scope of protection claimed by the present utility model.

Claims

1. A highly flexible venous stent, characterized in that: It includes a three-part support structure and a set of short metal connecting rods (5); The three-part stent, from proximal to distal, consists of: a proximal stent (1), a strong radial support stent (2), and a distal braided stent (4), connected in sequence. The proximal stent (1) is located at the junction of the two iliac veins, the strong radial support stent (2) is located at the segment of the common iliac vein that is prone to compression, and the distal braided stent (4) is located at the distal end of the common iliac vein and the external iliac vein. The radial support force of the three-part stent decreases in the following order: proximal stent (1) > strong radial support stent (2) > distal braided stent (4); The flexibility of the three-part stent decreases in the following order: distal braided stent (4) > strong radial support stent (2) > proximal stent (1); The distal braided stent (4) is formed by braiding coated metal wires. The expansion diameter of the stent is slightly larger than the target vein diameter but smaller than the strong radial support stent (2). The distal braided stent (4) includes a metal wire (401) and a coating located outside the metal wire (401). The coating is divided into an inner coating (402) and an outer coating (403). The inner coating has a larger arc ratio than the outer coating (403), and the surface roughness of the inner coating (402) is smaller than that of the outer coating (403). The set of metal connecting short rods (5) are connected by welding to two parts: a strong radial support bracket (2) and a braided bracket (4).

2. The highly flexible venous stent as described in claim 1, characterized in that: The proximal end of the proximal stent (1) is petal-shaped and slightly open to the outside.

3. The highly flexible venous stent as described in claim 1, characterized in that: The proximal stent (1) is an open-design bare metal stent manufactured by laser engraving technology; the material includes stainless steel, cobalt-chromium alloy, platinum-chromium alloy, and magnesium alloy.

4. The highly flexible venous stent as described in claim 3, characterized in that: The strong radial support stent (2) is a bare metal stent manufactured by laser engraving technology. The stent expansion diameter is greater than the target vein diameter, the metal wall thickness and metal coverage are greater than the distal braided stent (4), and the length is 2-4cm.

5. The highly flexible venous stent as described in claim 4, characterized in that: The density of the metal wires (401) is lower than that of the strong radial support force bracket (2), and the expansion diameter of the bracket is smaller than that of the strong radial support force bracket (2).

6. The highly flexible venous stent as described in claim 5, characterized in that: The coating is a polymer coating, and the coating material is a blood-compatible coating. The outer coating (403), which is in contact with the blood vessel wall, has a surface roughness of about 0.8-1.2 μm, and the inner coating (402), which is in contact with the blood, has a surface roughness of less than 50 nm.

7. The highly flexible venous stent as described in claim 6, characterized in that: The blood-compatible coating is polylactic acid-glycolic acid copolymer (PLGA).

8. The highly flexible venous stent as described in claim 5, characterized in that: The distal braided stent (4) is 4-6 cm long and covers the iliac vein across the joint.

9. The highly flexible venous stent as described in claim 1, characterized in that: The curvature of the inner coating (402) is in the range of 240°-270°, and the remaining part is the curvature range of the outer coating (403).

10. The highly flexible venous stent as described in claim 9, characterized in that: The inner coating (402) has the same thickness as the outer coating (403).

Images