Biodegradable large-diameter intravascular stent and preparation method thereof

Abstract

The invention discloses a biodegradable large-diameter intravascular stent and a preparation method thereof.The stent comprises a soft stent body and a hard stent body, the hard stent body comprises a woven fixing ring and a hard net pipe, and the soft stent body is connected with the hard stent body through the woven fixing ring; the other end of the woven fixing ring is fixedly connected with the hard net pipe; the large-diameter biodegradable stent has supporting force, prevents blood flow from being affected by vascular adhesion, has flexibility, adapts to the environment of blood vessel bending, and improves the treatment effect of the stent; the invention discloses a preparation method of a stent. The preparation method comprises the following steps: blow molding a hard stent pipe; performing laser cutting on the hard stent tube; weaving a soft bracket net body; the soft bracket is welded with a sealing end; spraying medicine on the surface of the stent; pressing, holding and forming the bracket; according to the stent packaging and the preparation method of the stent, the problem that the biodegradable large-diameter intravascular stent is difficult to prepare is solved, the stent can be used for large-scale production, and guidance is provided for manufacturing of other related products.

Description

Technical Field

[0001] The present invention relates to the field of vascular interventional medicine, and in particular to a biodegradable large-diameter vascular stent and a preparation method thereof. Background Art

[0003] Considering the physiological structure of large-diameter veins, vascular stents are required to have high structural support and good flexibility. At present, venous interventional stents are mostly made of nickel-titanium wire to adapt to the venous structure. For veins that have been severely compressed, there is still a risk of restenosis after the implantation of metal stents. Restenosis in the stent will cause the diameter of the vascular lumen to become smaller again, affecting blood flow, which may cause new clinical symptoms. Due to the permanent retention characteristics of metal stents, once problems occur (such as thrombosis, stent intrinsic stenosis, etc.), a second operation may be required. One operation not only increases the difficulty and pain of treatment for patients, but may also bring additional economic burdens. The permanent retention of metal stents may also affect the subsequent treatment of other diseased blood vessels of patients. For example, when interventional surgery is required again, the presence of metal stents may increase the difficulty and risk of surgery. Biodegradable stents are made of biodegradable or absorbable materials, such as polylactic acid (PLLA), polyanhydride, polycarbonate, etc. These materials have good tissue compatibility. Biodegradable stents are mostly used in smaller blood vessels such as coronary arteries. Large-diameter biodegradable stents are difficult to balance support strength and flexibility. Biodegradable silk braided stents have high flexibility but insufficient support strength. 3D printed or laser cut biodegradable stents have improved support performance but insufficient flexibility. Summary of the invention

[0004] The purpose of the present invention is to solve the problems raised in the above-mentioned background technology, and then propose a biodegradable large-diameter vascular stent and a preparation method thereof. The stent disclosed in the present invention is provided with two parts, a hard stent and a soft stent, so that the large-diameter biodegradable stent has both supporting force to avoid blood vessel adhesion affecting blood flow, and flexibility to adapt to the tortuous environment of blood vessels, thereby improving the therapeutic effect of the stent.

[0005] The technical solution adopted by the present invention to solve the technical problem is:

[0006] A biodegradable large-diameter vascular stent comprises a soft stent and a hard stent, wherein the hard stent comprises a braided fixing ring and a hard mesh tube, the soft stent is connected to the hard stent via the braided fixing ring, and the other end of the braided fixing ring is fixedly connected to the hard mesh tube.

[0007] Preferably, a developing ball pressing hole is provided at one end of the hard mesh tube away from the braided fixing ring, and a developing ball can be installed and fixed in the developing ball pressing hole to facilitate developing positioning during the stent surgery intervention process.

[0008] Preferably, the rigid mesh tube comprises a transverse bar and a longitudinal bar, wherein the transverse bar and the longitudinal bar are in a vertical fixed relationship, the longitudinal bar gradually decreases in width from right to left, the transverse bar is V-shaped, and the V-shaped angle of the transverse bar gradually increases from right to left. The right side of the rigid bracket is the distal end, and the left side is the proximal end. The distal end has a thick wall and a small inner diameter, and can penetrate into complex lesions (such as conical blood vessels) to provide strong support performance. The support ring design itself has more hollows, higher flexibility, and strong resistance to plastic deformation.

[0009] Preferably, a circle of weaving fixing holes is provided on the weaving fixing ring, the soft stent is composed of a wire group, the wire group passes through the weaving fixing holes, and the weaving fixing ring is both the starting point for weaving the soft stent and provides a fixed point for weaving the soft stent.

[0010] Preferably, the hard stent and the soft stent are made of polymers composed of polylactic acid (PLA) and poly-L-lactide-caprolactone (PLCL), which are biodegradable materials.

[0011] The present invention also discloses a method for preparing the above-mentioned biodegradable large-diameter vascular stent, which comprises the following steps:

[0012] 1) Blow molding of rigid bracket tubes. This process is completed by a blow molding device. The tubes initially extruded from the silo are fixed inside the bracket mold by upper and lower clamping calipers. Air is pressurized on the tubes in the bracket mold through the air duct. The tubes are pressed against the inner wall of the bracket mold under the action of pressure. The tubes in the bracket mold are heated on the outside by a hot air heating head. After the tubes are vitrified, the stretching motor installed above the upper clamping caliper stretches the tubes axially. The stretching speed of the stretching motor decreases from fast to slow with equal acceleration. The wall thickness of the finally formed tubes gradually increases from bottom to top, the outer diameter is consistent, and the inner diameter gradually decreases from bottom to top.

[0013] 2) Laser cutting of rigid bracket tubes. This process is completed by using a laser engraving device. The formed tube is sleeved on the engraving mandrel, and the outer side of the formed tube is sleeved with an engraving bushing. The engraving bushing and the laser head are used to engrave the formed tube according to the set program to engrave the formed tube into a rigid bracket.

[0014] 3) Weaving of the soft stent mesh, which is completed by a weaving machine. A weaving fixing hole is set on the hard stent for weaving connection. The weaving structure is the soft stent. At the same time, the hard stent and the soft stent are connected together. The soft stent adopts a double-layer weaving method of silk thread around the hole;

[0015] 4) The soft stent is welded and sealed. After the soft stent is woven, the ends of the silk thread are welded by a welding machine to form a corolla structure;

[0016] 5) Spraying drugs on the surface of the stent, spraying anti-proliferative drugs such as sirolimus or paclitaxel on the surface of the stent;

[0017] 6) Stent compression molding, using a crimping machine to reduce the size of the stent;

[0018] 7) Stent packaging: placing the crimped stent into a sterile packaging structure.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The stent disclosed in the present invention is provided with two parts, a hard stent and a soft stent, so that the large-diameter biodegradable stent has both supporting force to avoid blood vessel adhesion affecting blood flow and flexibility to adapt to the tortuous environment of blood vessels, thereby improving the therapeutic effect of the stent.

[0021] 2. The present invention discloses a stent with a developing ball pressing hole, in which a developing ball can be installed and fixed, so as to facilitate developing positioning during stent surgical intervention.

[0022] 3. The hard mesh tube structure of the stent disclosed in the present invention has a thick distal wall and a small inner diameter, which can penetrate deep into complex lesions (such as conical blood vessels) to provide strong supporting performance. The support ring design itself has more hollows, higher flexibility, and strong resistance to plastic deformation, which can adapt to the high pressure demand at the proximal end of the blood vessel and improve the stability of the stent and the medical effect.

[0023] 4. The stent disclosed in the present invention is made of biodegradable materials with good tissue compatibility, so that the stent can reduce rejection reactions during use, reduce stimulation to surrounding tissues, and is beneficial to the patient's recovery.

[0024] 5. The present invention discloses a method for preparing a stent, which solves the difficulty in preparing a biodegradable large-diameter vascular stent, can be used for large-scale production, and provides guidance for the manufacture of other related products. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the isometric structure of the bracket disclosed in the present invention;

[0026] Figure 2 It is a schematic diagram of the rigid support structure of the support disclosed in the present invention;

[0027] Figure 3 A schematic diagram of a blow molding device for producing a stent disclosed in the present invention;

[0028] Figure 4 This is a schematic diagram of a laser engraving device for stent production disclosed in the present invention;

[0029] Figure 5 The present invention discloses a flow chart of the preparation of the stent.

[0030] Among them: 1. Hard bracket; 11. Developing ball pressing hole; 12. Braided fixing ring; 121. Braided fixing hole; 13. Hard mesh tube; 131. Cross bar; 132. Longitudinal bar; 2. Soft bracket; 3. Blow molding device; 31. Stretching motor; 32. Upper clamping caliper; 33. Bracket mold; 34. Hot air heating head; 35. Lower clamping caliper; 36. Air duct; 4. Laser engraving device; 41. Engraving mandrel; 42. Molding pipe; 43. Engraving bushing; 44. Laser head. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0032] Embodiment 1, as Figure 1-Figure 5 As shown, a biodegradable large-diameter vascular stent includes a soft stent 2 and a hard stent 1, wherein the hard stent 1 includes a braided fixing ring 12 and a hard mesh tube 13, wherein the soft stent 2 is connected to the hard stent 1 via the braided fixing ring 12, and the other end of the braided fixing ring 12 is fixedly connected to the hard mesh tube 13, wherein the hard stent 1 enables the large-diameter biodegradable stent to have both supporting force and avoid blood vessel adhesion affecting blood flow, and the soft stent 2 is also flexible and adapts to the tortuous environment of the blood vessel, thereby improving the therapeutic effect of the stent.

[0033] like Figure 1 and Figure 2 As shown, a developing ball pressing hole 11 is provided at one end of the hard mesh tube 13 away from the braided fixing ring 12, and a developing ball can be installed and fixed in the developing ball pressing hole 11, so as to facilitate the developing positioning during the stent surgery intervention process;

[0034] The rigid mesh tube 13 includes a transverse bar 131 and a longitudinal bar 132, wherein the transverse bar 131 and the longitudinal bar 132 are in a vertical fixed relationship, the longitudinal bar 132 gradually decreases in width from right to left, the transverse bar 131 is V-shaped, and the V-shaped angle of the transverse bar 131 gradually increases from right to left. The right side of the rigid support 1 is the distal end, and the left side is the proximal end. The supporting force required on the right side of the rigid support 1 is greater than that on the left side of the rigid support 1. The desired effect can be achieved through the above-mentioned rigid mesh tube 13 structure.

[0035] like Figure 1As shown, a circle of braiding fixing holes 121 is set on the braiding fixing ring 12, and the soft stent 2 is composed of a wire group, and the wire group passes through the braiding fixing holes 121. The braiding fixing ring 12 is both the starting point of the braiding of the soft stent 2 and provides a fixed point for the braiding of the soft stent 2. The soft stent 2 has high flexibility and can maintain a certain supporting performance, which is conducive to passing through more complex blood vessel channels.

[0036] like Figure 1 As shown, the hard stent 1 and the soft stent 2 are made of polymers composed of polylactic acid (PLA) and poly-L-lactide-caprolactone (PLCL), which are biodegradable materials with good tissue compatibility, so that the stent can reduce rejection during use, reduce stimulation to surrounding tissues, and is beneficial to the patient's recovery; the biodegradable stent does not contain metal materials, so it will not affect the patient's CT, MRI and other examinations; the biodegradable stent can be absorbed or excreted by the human body after degradation, so the patient can receive re-treatment when needed. This provides patients with more treatment options and opportunities, which is conducive to dealing with possible problems such as vascular restenosis and reducing complications.

[0037] like Figure 2-Figure 5 As shown, the present invention also discloses a method for preparing the above-mentioned biodegradable large-diameter vascular stent, and the preparation method comprises the following steps:

[0038] 1) Blow molding of rigid bracket tubes. This process is completed by using a blow molding device 3. The tubes initially extruded from the silo are fixed inside the bracket mold 33 by an upper clamping caliper 32 and a lower clamping caliper 35. Air is pressurized on the tubes in the bracket mold 33 through an air duct 36. The tubes are pressed against the inner wall of the bracket mold 33 under the action of pressure. The tubes in the bracket mold 33 are heated on the outside by a hot air heating head 34. After the tubes are vitrified, a stretching motor 31 installed above the upper clamping caliper 32 stretches the tubes axially. The stretching speed of the stretching motor 31 decreases from fast to slow with equal acceleration. The wall thickness of the finally formed formed tube 42 gradually increases from bottom to top, the outer diameter is consistent, and the inner diameter gradually decreases from bottom to top.

[0039] 2) Laser cutting of the rigid bracket tube, which is completed by using a laser engraving device 4, wherein a molded tube 42 is sleeved on an engraving mandrel 41, and an engraving bushing 43 is sleeved on the outer side of the molded tube 42. The engraving bushing 43 and a laser head 44 are used to engrave the molded tube 42 according to a set program, and the molded tube 42 is engraved into a rigid bracket 1;

[0040] 3) Weaving of the soft support mesh, which is completed by a weaving machine. A weaving fixing hole 121 is provided on the hard support 1 for weaving connection. The weaving structure is the soft support 2. The hard support 1 and the soft support 2 are connected together. The soft support 2 is woven in a double-layer manner by winding the silk thread around the hole;

[0041] 4) Welding and sealing the ends of the soft stent. After the soft stent 2 is woven, the ends of the silk thread are welded by a welding machine to form a corolla structure, so that the stent connection is more stable and the stent surface is smoother;

[0042] 5) Spraying drugs on the surface of the stent. Spraying anti-proliferative drugs, such as sirolimus or paclitaxel, on the surface of the stent can prevent thrombosis in the stent after surgery. At low concentrations, both sirolimus and paclitaxel can inhibit endothelial cell proliferation without obvious toxicity.

[0043] 6) Stent compression molding: using a crimping machine to reduce the size of the stent to facilitate moving the stent to the desired position in the blood vessel;

[0044] 7) Stent packaging: placing the crimped stent into a sterile packaging structure.

[0045] Embodiment 2, as Figure 2-Figure 5 As shown, the present invention also discloses a method for preparing the above-mentioned biodegradable large-diameter vascular stent, and the preparation method comprises the following steps:

[0046] 1) Blow molding of the rigid support tube, which is completed by the blow molding device 3. The tube initially extruded from the silo is fixed inside the support mold 33 by the upper clamping caliper 32 and the lower clamping caliper 35. The air is pressurized on the tube in the support mold 33 through the air duct 36. The tube is pressed against the inner wall of the support mold 33 under the action of pressure. The upper and lower ends of the support mold 33 are made of heat-insulating materials, and the middle of the support mold 33 is made of metal heat-conducting materials. An electromagnetic heating device is arranged on the outside of the support mold 33, and the tube in the support mold 33 is heated by the electromagnetic heating device. After the tube is vitrified, the stretching motor 31 installed above the upper clamping caliper 32 stretches the tube axially. The stretching speed of the stretching motor 31 decreases from fast to slow with equal acceleration. The wall thickness of the finally formed formed tube 42 gradually increases from bottom to top, the outer diameter is consistent, and the inner diameter gradually decreases from bottom to top;

[0047] 2) Laser cutting of the rigid bracket tube, which is completed by using a laser engraving device 4, wherein a molded tube 42 is sleeved on an engraving mandrel 41, and an engraving bushing 43 is sleeved on the outer side of the molded tube 42. The engraving bushing 43 and a laser head 44 are used to engrave the molded tube 42 according to a set program, and the molded tube 42 is engraved into a rigid bracket 1;

[0048] 3) Weaving of the soft support mesh, which is completed by a weaving machine. A weaving fixing hole 121 is provided on the hard support 1 for weaving connection. The weaving structure is the soft support 2. The hard support 1 and the soft support 2 are connected together. The soft support 2 is woven in a double-layer manner by winding the silk thread around the hole;

[0049] 4) Welding and sealing the ends of the soft stent. After the soft stent 2 is woven, the ends of the silk thread are welded by a welding machine to form a corolla structure, so that the stent connection is more stable and the stent surface is smoother;

[0050] 5) Spraying drugs on the surface of the stent. Spraying anti-proliferative drugs, such as sirolimus or paclitaxel, on the surface of the stent can prevent thrombosis in the stent after surgery. At low concentrations, both sirolimus and paclitaxel can inhibit endothelial cell proliferation without obvious toxicity.

[0051] 6) Stent compression molding: using a crimping machine to reduce the size of the stent to facilitate moving the stent to the desired position in the blood vessel;

[0052] 7) Stent packaging: placing the crimped stent into a sterile packaging structure.

[0053] It should be noted that the production device of the bracket disclosed in the present invention is that the blow molding device 3, the laser engraving device 4 and the braiding machine only display some parts, and the main structure of the device can adopt the technical solution.

[0054] It should be noted that when the stent disclosed in the present invention is in use, a pebax balloon is placed inside the stent, and the pebax balloon is fixed to the stent after inflation. After the stent reaches the installation position, it is inflated again to assist the stent in expanding, so that the outer wall of the stent contacts the inner wall of the blood vessel, thereby achieving the purpose of expanding and supporting the blood vessel. The pebax balloon is a compliant balloon with a soft material, and can perfectly fit the stent during the inflation process.

[0055] In the description of the present invention, the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "vertical", "horizontal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the purpose of describing the present invention rather than requiring the present invention to be constructed or operated in a specific position, and therefore should not be construed as limiting the present invention. The terms "connected" and "connected" in the present invention should be understood in a broad sense, for example, it can be a connection or a detachable connection; it can be a direct connection or an indirect connection through an intermediate component. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0056] The above is the preferred operation mode of the present invention, and the description of the specific operation mode is only used to better understand the concept of the present invention. For ordinary technicians in this technical field, several improvements or equivalent substitutions can be made according to the principles of the present invention, and these improvements or equivalent substitutions are also considered to fall within the protection scope of the present invention.

Claims

1. A biodegradable large-diameter vascular stent, comprising a soft stent (2), characterized in that: It also comprises a hard support (1), wherein the hard support (1) comprises a braided fixing ring (12) and a hard mesh tube (13), the soft support (2) is connected to the hard support (1) via the braided fixing ring (12), and the other end of the braided fixing ring (12) is fixedly connected to the hard mesh tube (13).

2. The biodegradable large-diameter vascular stent according to claim 1, characterized in that: A developing ball pressing hole (11) is provided at one end of the hard mesh tube (13) away from the braiding fixing ring (12).

3. The biodegradable large-diameter vascular stent according to claim 1, characterized in that: The hard mesh tube (13) comprises a cross bar (131) and a longitudinal bar (132), wherein the cross bar (131) and the longitudinal bar (132) are in a vertical fixed relationship, the longitudinal bar (132) gradually decreases in width from right to left, the cross bar (131) is V-shaped, and the V-shaped angle of the cross bar (131) gradually increases from right to left.

4. The biodegradable large-diameter vascular stent according to claim 1, characterized in that: A circle of braiding fixing holes (121) is provided on the braiding fixing ring (12), and the soft support (2) is composed of a wire group, and the wire group passes through the braiding fixing holes (121).

5. The biodegradable large-diameter vascular stent according to claim 1, characterized in that: The hard support (1) and the soft support (2) are made of a polymer consisting of polylactic acid and poly-L-lactide-caprolactone.

6. A method for preparing a biodegradable large-diameter vascular stent according to any one of claims 1 to 5, characterized in that , the preparation method comprises the following steps: 1) Blow molding of a rigid support tube, which is completed by a blow molding device (3). The tube initially extruded from the silo is fixed inside the support mold (33) by an upper clamping caliper (32) and a lower clamping caliper (35). Air is pressurized on the tube in the support mold (33) through an air duct (36). The tube in the support mold (33) is heated on the outside by a hot air heating head (34). After the tube is vitrified, a stretching motor (31) installed above the upper clamping caliper (32) stretches the tube axially. The stretching speed of the stretching motor (31) decreases from fast to slow with equal acceleration. The wall thickness of the finally formed molded tube (42) gradually increases from bottom to top, the outer diameter is consistent, and the inner diameter gradually decreases from bottom to top. 2) Laser cutting of the rigid support tube, which is completed by using a laser engraving device (4), wherein a molded tube (42) is sleeved on an engraving mandrel (41), an engraving bushing (43) is sleeved on the outer side of the molded tube (42), and the molded tube (42) is engraved by using the engraving bushing (43) and a laser head (44) according to a set program, so that the molded tube (42) is engraved into a rigid support (1); 3) Weaving the soft support mesh, which is completed using a weaving machine. A weaving fixing hole (121) is provided on the hard support (1) for weaving connection. The weaving structure is the soft support (2). The hard support (1) and the soft support (2) are connected together. The soft support (2) is double-layer woven by winding a silk thread around the hole. 4) Welding and sealing the ends of the soft stent. After the soft stent (2) is woven, the ends of the silk thread are welded by a welding machine to form a corolla structure; 5) Spraying drugs on the surface of the stent, spraying anti-proliferative drugs on the surface of the stent; 6) Stent compression molding, using a crimping machine to reduce the size of the stent; 7) Stent packaging: placing the crimped stent into a sterile packaging structure.

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