CN110522540B - Orderly and completely degradable film-covered double-layer stent - Google Patents

Abstract

Translated fromChinese

本发明公开了一种可有序完全降解的覆膜双层支架，属于医疗器械技术领域。该覆膜双层支架包括外层裸支架和内层覆膜支架。支架部分采用可降解金属及其合金或可降解高分子材料，展开方式为球囊扩张型。覆膜采用可降解高分子材料，外层裸支架先行释放，能先通过病变的狭窄段，内层覆膜支架的位置和长度可以根据动脉瘤颈和夹层动脉瘤破口的情况决定。内层覆膜支架释放时，压入并固定在外层裸支架上，可以治疗距离重要旁支血管很近的动脉瘤。在动脉瘤血栓化并收缩至自然状态后，该覆膜双层支架按照下面的顺序依次降解：覆膜降解、内层支架降解，外层裸支架降解，最终完全降解，避免体内长期存在异物，避免长期服用抗血栓药物。

The invention discloses an orderly and completely degradable film-covered double-layer stent, which belongs to the technical field of medical devices. The covered double-layer stent includes an outer bare stent and an inner covered stent. The stent part adopts degradable metal and its alloy or degradable polymer material, and the expansion method is balloon expansion type. The coating is made of degradable polymer materials. The outer layer of the stent is released first and can pass through the stenotic section of the lesion first. The position and length of the inner layer of the stent-graft can be determined according to the aneurysm neck and the rupture of the dissecting aneurysm. When the inner stent-graft is released, it is pressed and fixed on the outer bare stent, which can treat aneurysms that are very close to important collateral vessels. After the aneurysm is thrombosed and shrunk to a natural state, the covered double-layer stent is degraded in the following order: the covered stent degrades, the inner stent degrades, the outer bare stent degrades, and finally completely degrades to avoid long-term foreign bodies in the body, Avoid long-term use of antithrombotic drugs.

Description

Orderly and completely degradable film-covered double-layer stent

Technical Field

The invention relates to the technical field of medical instruments, in particular to a film-covered double-layer stent capable of being degraded orderly and completely.

Technical Field

The pathological changes of the vascular diseases, such as the dissecting aneurysm, the aneurysm and the like, can be treated by adopting a covered stent. The treatment principle is that the covered stent forms a barrier at the rupture of the dissected aneurysm and the neck of the aneurysm, when blood flow does not flow into the aneurysm any more, the blood remaining in the aneurysm forms thrombus and is organized into vascular tissue, the expanded aneurysm wall shrinks due to negative pressure, and the space occupying effect is reduced, so that the purpose of treating the aneurysm is achieved.

Currently, there are commercially available stent grafts: intracranial covered stents such as Willis and the like, coronary covered stents such as JOSTENT Graftmaster stents and Symbiot stents, aortic covered stents such as Valiant Captivia stents and Endurant II stents and the like. These stent grafts are permanent stents, and both the stent and the stent graft are made of non-degradable materials, for example, Polytetrafluoroethylene (PTFE) is used as the stent graft, and eventually foreign materials are left in the body, which may cause the stent to be displaced and require long-term administration of antithrombotic drugs. Meanwhile, the film can block the blood flow path of important collateral blood vessels around the lesion, and the life quality of the patient is reduced.

Patent 1 discloses a biodegradable film part covered stent for treating bifurcation lesion coronary artery perforation, which is a two-layer stent clamping a layer of degradable film, and can ensure the circulation of important collateral blood vessels and timely cover the perforation part. After the stent finishes the treatment function, the covering film is degraded by self, but the double-layer stent is not degraded and is always left in the blood vessel.

Patent 2 discloses a degradable covered stent, which is a single-layer covered stent capable of being completely degraded, but has the risk of plugging important collateral blood vessels, and meanwhile, the covered stent has poor flexibility and is difficult to pass through bent blood vessels.

The covered stents disclosed inpatent 3 and patent 4 are single-layer degradable covered stents with adjustable covered region size and position, and can avoid blocking other branch vessels, but the flexibility of the whole covered stent is inferior to that of a bare stent, and the covered stent is difficult to pass through the lesion region of aneurysm caused by arteriosclerosis and is not beneficial to the release of the covered stent.

Therefore, there is a need for a stent graft that is fully degradable, ensures the circulation of important collateral vessels, and passes through a stenotic lesion.

Prior art documents:

patent 1, CN 108158701 a, patent of schoolwork, bushlung, bio-absorbable membrane partial tectorial membrane stent for treating bifurcation lesion coronary perforation

Patent 2, CN 207085001U, Zhujian, Chenshao, a degradable stent graft

Patent No. 3, CN 106175983A, Chenshui, Chenlianglong, Caiwei et al, covered stent and method for producing the same

Patent 4, CN 106667621 a, guowei, dolocaxin, a novel bioabsorbable tectorial membrane drug-loaded stent for femoral popliteal artery

Disclosure of Invention

The invention aims to provide a covered stent which can be completely degraded, can ensure the circulation of important collateral blood vessels and can pass through a lesion narrow section.

An orderly and completely degradable tectorial membrane double-layer stent is characterized by comprising an outer-layer naked stent and an inner-layer tectorial membrane stent, wherein the inner-layer tectorial membrane stent comprises a tectorial membrane and a stent layer; the stent part adopts biodegradable metal and alloy thereof or a biodegradable high polymer material, the expansion mode is a balloon expansion type, and the covering film adopts the biodegradable high polymer material; the outer-layer bare stent is released in advance, a false cavity of the dissected aneurysm can be pressed and a fixing place is provided for the inner-layer covered stent through a narrow section of a pathological change, the inner-layer covered stent is released later and fixed on the outer-layer stent through compressive stress, and the release position, the length and the number of the stent can be determined according to the rupture conditions of the aneurysm neck and the dissected aneurysm; the degradation of the covered double-layer stent is orderly, and in the degradation process, the covered membrane is kept complete before the organization in the aneurysm and the healing of the vascular laceration; when the tectorial membrane is completely degraded within half a year to 1 year, the support capability of the stent layer of the inner layer tectorial membrane stent is not lost; when the stent layer of the inner-layer covered stent is completely degraded within 1-3 years, the supporting capability of the outer-layer bare stent is not lost, and finally the outer-layer bare stent is completely degraded within 3-5 years.

Further, the selection principle of the bracket material is as follows: before implantation, the tensile strength is higher than 300MPa, the yield strength is higher than 200MPa, and the elongation is greater than 20%; after the implant, in the first six months of the degradation process, the yield strength of the outer layer bare stent material is higher than 150MPa, the yield strength of the inner layer stent material is higher than 100MPa, and degradation products are nontoxic; the inner and outer layer brackets are made of Mg and alloy thereof, Zn and alloy thereof, Fe and alloy thereof and polylactic acid material; the stent layers of the outer bare stent and the inner covered stent are made of the same or different materials; when the stent is made of a heterogeneous material, the degradation rate of the inner-layer stent material is higher than that of the outer-layer bare stent material; if both are made of metal materials, the corrosion potential of the inner stent material is lower than that of the outer bare stent material.

Furthermore, the film-coating material is a biodegradable high polymer material, polylactic acid (PLA), levorotatory polylactic acid (PLLA), polycaprolactone and polyglycolic acid are selected, and the film-coating material is degraded within half a year to 1 year by regulating and controlling the tissues of the film-coating material; meanwhile, the tectorial membrane of the inner-layer tectorial membrane stent is connected with the stent layer in a heat seal or stamping way.

Furthermore, the coverage rate of the outer bare stent is 10% -20%, the coverage rate of the inner covered stent is 20% -30%, and the coverage rate of the outer stent is lower than that of the inner stent, so that the smoothness of important side branch blood vessels is ensured.

Further, the thickness of the outer-layer bare stent is 50-150 microns, the thickness of the stent layer of the inner-layer covered stent is 20-80 microns, the thickness of the outer-layer stent is larger than that of the inner-layer stent, and the influence of the fixation of the inner-layer covered stent on the outer-layer bare stent can be reduced due to the thickness difference of the stent layers of the inner-layer covered stent and the outer-layer stent.

The scheme of the invention for realizing the aim is as follows: designing and manufacturing a film-covered double-layer stent which can be orderly and completely degraded. The stent comprises an outer-layer naked stent and an inner-layer covered stent. The stent coverage rate of the outer bare stent is low, the outer bare stent is preferentially released, the outer bare stent can pass through a narrow section of a pathological change firstly, a false cavity of the dissected aneurysm can be pressed, a fixing place is provided for the release of the inner covered stent, and the circulation of a collateral blood vessel is not hindered after the outer bare stent is implanted. The length and the release position of the inner-layer covered stent are selected according to the conditions of an aneurysm opening and a dissection aneurysm opening, the thickness of the inner-layer covered stent is smaller than that of the outer-layer bare stent, the inner-layer covered stent is pressed on the outer-layer bare stent through balloon expansion, and the inner-layer covered stent is better fixed on the outer-layer bare stent through the compressive stress generated by plastic deformation, so that the displacement caused by the influence of blood flow is avoided. After the aneurysm is thrombosed and contracted to a natural state, the covered double-layered stent is degraded in the following order: degrading the coated film, degrading the inner layer stent and degrading the outer layer bare stent. Finally, the covered double-layer stent is completely degraded in human blood vessels.

Further, the inner-layer covered stent consists of a covering film and a stent layer, and the covering film and the stent layer are connected in a heat seal or stamping mode and the like. In the implantation process, the outer-layer bare stent is released after the outer-layer bare stent is released, the outer-layer bare stent released firstly presses a false cavity of the dissected aneurysm and provides a fixing place for the inner-layer covered stent. The inner-layer covered stent and the outer-layer bare stent are fixed through the compression stress, are not in direct contact with the vascular wall, can adjust the length and the release position of the inner-layer covered stent according to the vascular lesion condition, and are suitable for treating the aneurysm of which the aneurysm opening is close to an important side branch vessel. For the dissected aneurysm which is pressed by the outer bare stent, the inner-layer covered stent only needs to cover the laceration of the dissected aneurysm, aiming at the disease condition, the length of the inner-layer covered stent can be greatly reduced, the flexibility of the inner-layer covered stent is also obviously improved, and the treatment effect is obviously improved under the condition that a plurality of side branch blood vessels are arranged nearby. When the dissecting aneurysm has a plurality of crevasses at the near end and the far end of the important side branch blood vessel simultaneously, so that a blood flow passage is formed in the false cavity, two or more inner layer covered stents can be adopted to respectively block the crevasses, and the important side branch blood vessel is reserved.

The invention provides a design principle of an outer-layer bare stent and an inner-layer covered stent structure, which comprises the following steps: the coverage rate of the outer bare stent is 10-20%, which is less than the coverage rate (20-30%) of the stent layer of the inner covered stent, and the shielding effect of the outer bare stent on important collateral blood vessels is reduced. The specific structure may be an open-loop or closed-loop structure such as a corrugated type, a Z-type, and a mesh type. The following is a detailed description of the corrugated structure, and other structures can be designed according to the above design principle. The medical device company may adjust the stent size and coverage according to the patient's specific condition.

The invention provides a selection principle of a bracket material, which comprises the following steps: before implantation, the initial tensile strength is higher than 300MPa, the yield strength is higher than 200MPa, the elongation is larger than 20%, in the first six months of degradation after implantation, the yield strength of the outer layer bare stent material is higher than 150MPa, the yield strength of the inner layer stent material is higher than 100MPa, and degradation products are nontoxic. The initial tensile strength and the elongation percentage ensure that the stent is not broken when the saccule is expanded, the diameter of the selected stent is 10-20% larger than the diameter of a normal blood vessel, when the saccule is contracted, the stent is contracted under the resilience force of the blood vessel wall and reaches balance, when the invention is used for aneurysm caused by atherosclerosis, the stent can also be subjected to the resilience force of compressed fat and cholesterol, so the initial yield strength required by the stent material is higher than 200MPa, after 6 months, endothelialization of a lesion position is basically finished, the yield strength of an outer bare stent can be properly reduced to 150MPa, and the inner stent is mainly used for laminating a covering film on the outer bare stent, so the yield strength of the inner stent can be lower than that of the outer bare stent but higher than 100 MPa.

The stent layers of the outer bare stent and the inner covered stent can be made of degradable metals and alloy materials thereof or degradable high polymer materials, for example, Mg and alloy thereof, Zn and alloy thereof, Fe and alloy thereof, polylactic acid materials and the like. Specifically, zinc alloys are exemplified below, and those satisfying the above performance criteria can be selected, and among them, Zn-Li-based and Zn-Mn-based alloys are preferable. Specifically, the Zn-Li-based alloy includes a Zn-Li binary alloy and a Zn-Li-X multi-element alloy, wherein X is at least one of Cu, Mg, Fe, Ge, Ca and rare earth elements; the Zn-Mn-based alloy is mainly Zn-Mn-Y multi-element alloy, wherein Y is at least one of Li, Cu, Mg, Ca, Ag and rare earth elements.

In order to more clearly explain the contents of the present invention, a Zn-0.8Li alloy will be specifically explained below as an example. The alloy is processed and formed by a preparation process designed by the applicant of the invention, and the forming method is shown in CN 108372203A, Wanluning, Haoyuan, Shizhengzhi, a rolling method of biomedical degradable Zn-Li alloy. After forming, the tensile strength of the alloy is higher than 300MPa, the yield strength is higher than 200MPa, and the elongation is more than 20%. The degradation rate of the plasma soaked in the simulated plasma is 3.83 mu m/a (a represents year), namely, the thickness reduction rate of the plasma soaked in a single side is 3.83 mu m/a, and the thickness reduction rate of the plasma soaked in a double side is 7.66 mu m/a. The degradation rate is obviously higher than that of biodegradable pure iron and biodegradable pure magnesium alloy, and obviously lower than that of biodegradable pure magnesium and biodegradable pure magnesium alloy, so that the biodegradable magnesium alloy can provide enough long-time supporting capability for treating vascular diseases, and can not be retained in a human body for a long time due to too slow degradation. The Zn-0.8Li alloy is soaked in simulated plasma for 6 months, the tensile strength is always higher than 300MPa, the elongation is always higher than 20%, the yield strength is reduced in the period, the yield strength is reduced to 166MPa (shown in Table 1) at 6 months, but still higher than 150MPa, and the barrier of the normal function of the stent is not formed. The Zn-0.8Li alloy stent can play the design role in simulated plasma for at least 6 months. In addition, the degradable Zn-Li-based and Zn-Mn-based alloys have certain anticoagulation effect, and the dosage of anticoagulation medicaments can be reduced.

TABLE 1 mechanical properties of Zn-0.8Li alloy before and after immersion in simulated plasma

The film is made of degradable polymers, polylactic acid (PLA), levorotatory polylactic acid (PLLA), polycaprolactone, polyglycolic acid and the like can be selected, the film is located between the stent layers of the outer-layer bare stent and the inner-layer covered stent, and the thickness of the film is 10-80 microns. And the degradation rate of the film material is controlled by regulating the tissue of the film material, so that the film can be kept intact before the aneurysm is thrombosed and shrinks to the natural state, and can be completely degraded within half a year to 1 year.

In order to ensure that the inner-layer stent is completely degraded before the outer-layer bare stent and ensure that the outer-layer bare stent keeps the mechanical supporting effect before the inner-layer stent is completely degraded. The invention provides that the thickness of the outer layer bare stent is larger than that of the inner layer covered stent, and the specific thickness range is related to the position of a lesion. Preferably, the thickness of the outer-layer bare stent is 50-200 mu m, and the thickness of the stent layer of the inner-layer covered stent is 20-100 mu m. After the tectorial membrane is completely degraded, the area of the stent layer of the inner-layer tectorial membrane stent contacting with blood is increased, and the inner-layer tectorial membrane stent can be completely degraded in a shorter time. The thickness difference of the stent layers of the inner-layer stent and the outer-layer stent is beneficial to prolonging the service time of the outer-layer bare stent and simultaneously is beneficial to fixing the inner-layer covered stent on the outer-layer bare stent, so that the stent is prevented from shifting. According to the invention, in the degradation process of the covering film, on the premise that the stent layer of the inner-layer covered stent does not lose integrity and support performance, the stent layer of the inner-layer covered stent can be made of a degradable material with a degradation rate higher than that of the outer-layer bare stent, if the inner-layer stent and the outer-layer stent are made of metal or alloy materials, the corrosion potential of the material of the inner-layer stent layer is lower than that of the metal and alloy of the outer-layer bare stent, and the later degradation of the stent layer of the inner-layer covered stent is accelerated by using macroscopic galvanic corrosion. So when the inner and outer layers are dissimilar materials, for example, when the outer bare stent is Fe and its alloys, the inner stent layer can be polylactic acid or Fe-based alloys with lower corrosion potential, Zn and its alloys, Mg and its alloys. When the outer bare stent is polylactic acid, the inner stent can be polylactic acid with lower molecular weight or Mg and alloy thereof and the like.

The invention has the advantages that compared with the prior art documents:

(1) provides a tectorial membrane double-layer stent which can be orderly and completely degraded, and comprises an outer-layer naked stent and an inner-layer tectorial membrane stent. The bare stent on the outer layer is preferentially implanted, can pass through a narrow section of pathological changes firstly, can press the false cavity of the interlayer aneurysm, is favorable for closing the laceration, and the covered stent on the inner layer can block the blood flow exchange between the aneurysm and the tumor-carrying blood vessel. Meanwhile, the coverage rate of the outer-layer bare stent is low, and the circulation of important collateral blood vessels is ensured. The inner-layer covered stent is fixed by pressing the outer-layer bare stent into the inner-layer covered stent, but not by pressing the inner-layer covered stent into a normal blood vessel wall, so that the inner-layer covered stent can adapt to the aneurysm of which the aneurysm opening is close to an important side branch blood vessel. After the aneurysm is thrombosed and shrinks to the natural state, the tectorial membrane of the inner layer tectorial membrane support degrades within half a year to 1 year, the inner layer support layer degrades within 1 year to 3 years, and finally the outer layer naked support loses the mechanical property and degrades completely within 3-5 years. Avoiding foreign matters remaining in blood vessels and avoiding long-term use of antithrombotic drugs.

(2) Compared with thepatent 1, the position, the length and the number of the inner-layer covered stent adopted by the invention can be adjusted according to the pathological changes, and the inner-layer covered stent has no fixed position relation with the outer-layer bare stent, and can treat the conditions of a plurality of crevasses and the like. Meanwhile, the tectorial membrane and the stent part of the tectorial membrane double-layer stent can be degraded, thereby avoiding foreign matters remaining in blood vessels and avoiding long-term use of antithrombotic drugs.

(3) Compared withpatent 2, the invention adopts the covered double-layer stent, the outer bare stent can provide a fixing place for the inner covered stent, so that the length of the inner covered stent is reduced, the flexibility of the whole stent is improved, the stent is suitable for bending diseased blood vessels, and important collateral blood vessels can be avoided. Meanwhile, the coverage rate of the outer bare stent can ensure the circulation of important collateral blood vessels.

(4) Compared with thepatent 3 and the patent 4, the invention adopts the film-covered double-layer stent, the outer-layer bare stent has better flexibility, can firstly pass through the narrow section of pathological changes, and can also provide a fixing place for the inner-layer film-covered stent, so that the length of the inner-layer film-covered stent is reduced, and the flexibility of the whole stent is kept at a higher level.

Drawings

Fig. 1 is a development view (left) and a three-dimensional view (right) of an outer bare stent.

FIG. 2 is a development view (left) of the stent layer of the inner stent graft and a three-dimensional view (right) of the inner stent graft.

FIG. 3 is a three-dimensional view of a covered double-layered stent.

Fig. 4 is a sectional view a-a of fig. 3.

FIG. 5 is an enlarged partial view of a covered double-layered stent.

FIG. 6 is a partial cross-sectional view of a covered double-layered stent.

FIG. 7 is a schematic representation of the present invention for treating intracranial saccular aneurysms in close proximity to a significant side branch vessel. Sequentially comprises the following steps: schematic of intracranial saccular aneurysm next to important side branch vessels (top), effect after preferential release of outer bare stent (middle), and final effect after release of inner stent graft (bottom).

FIG. 8 is a schematic representation of the present invention for treating a partial type E abdominal aortic aneurysm. Sequentially comprises the following steps: part E-type abdominal aortic aneurysm (left), effect graph after preferential release of outer bare stent (center), and final effect graph after release of inner stent graft (right).

Fig. 9 is a schematic illustration of the present invention for treating arterial wall rupture bleeding. Sequentially comprises the following steps: schematic representation of artery wall rupture (left) and final effect plot after balloon-expansion of the covered double-layered stent in one piece (right).

Fig. 10 is a schematic view of a dissecting aneurysm for different conditions on both sides of a vertebral artery.

Fig. 11 is a schematic view of the present invention treating the vertebral dissection aneurysm of fig. 10. Sequentially comprises the following steps: the effect diagram (left) after the outer bare stent is released for the left side interbedded aneurysm of vertebral artery in fig. 10 under the protection of the distal brain protection device, and the final effect diagram (right) after the outer bare stent and the inner layer covered stent are sequentially released for the two side interbedded aneurysms of vertebral artery in fig. 10 and the thrombus collected by the distal brain protection device is removed.

In the figure: 1-outer bare stent; 2-inner layer tectorial membrane stent; 2 a-coating of the inner layer film-coated stent; 2 b-a stent layer of the inner-layer covered stent; 3-intracranial saccular aneurysm; 4-intracranial parent artery; 5-the important side branch of the parent artery; 6-abdominal aorta; 7-renal artery; 8-common iliac artery; 9-abdominal aortic aneurysm; 10-ruptured arterial wall vessels; 11-artery wall breach; 12-critical side branch vessels; 13-posterior cerebral artery; 14-basilar artery; 15-left vertebral artery; 16-left cerebellum posterior inferior artery; 17-left vertebral dissection aneurysm; 18-right vertebral artery; 19-posterior lower cerebellum artery on the right side; 20-right vertebral interbed aneurysm; 21-distal laceration of right vertebral artery interlayer aneurysm; 22-a distal brain protection device; 23-a laceration left after the left vertebral artery interlayer aneurysm is pressed; 24-a proximal laceration left after the right vertebral artery interlayer aneurysm is pressed; 25-distal laceration left after the right side vertebral artery interlayer aneurysm is pressed.

Detailed Description

In order to make the technical solution of the present invention more apparent, the present invention is further described in detail with reference to the following examples. The following examples are intended to illustrate the invention and are not intended to limit the invention.

As shown in figures 1-6, the double-layered covered stent of the invention consists of an outerbare stent 1 and an innercovered stent 2. Wherein, the inner-layer coveredstent 2 comprises a coveredstent 2a and astent layer 2 b. The connection mode between the coveringfilm 2a and thestent layer 2b is heat sealing, stamping, or the like. Wherein, the thickness of thestent layer 2b of the inner-layer covered stent is smaller than that of the outer-layerbare stent 1, and the specific thickness range is related to the position of a lesion. The material of thecovering film 2a takes levorotatory polylactic acid (PLLA) as an example, and the degradation rate of the covering film is controlled by regulating the tissue of the polymer.

Example 1: treatment of partial intracranial saccular aneurysms

As shown in fig. 7, for ananeurysm 3 of an intracranial straight blood vessel 4, when the distance between the aneurysm opening and an importantcollateral branch 5 is large, the inner-layer stent graft 2 may be directly used, and when the distance between the aneurysm opening and the importantcollateral branch 5 is small but the lesion does not involve the importantcollateral branch 5, the double-layer stent graft (1 and 2) needs to be used. Because when thestent graft 2 is used alone, a normal blood vessel wall long enough to fix thestent graft 2 is required between theaneurysm 3 and theimportant side branch 5; and when adopting tectorial membrane double-deck support (1 and 2), whole inlayertectorial membrane support 2 all can be fixed on outernaked support 1, so stability can be higher, simultaneously, tectorial membrane length only need slightly be greater than the tumor mouth to avoid the aneurysm rethread.

In a specific operation, the outer layerbare stent 1 is firstly released at a lesion position, and the outer layerbare stent 1 should cross the tumor mouth of thesaccular aneurysm 3 and the opening of the important sidebranch blood vessel 5. Angiography ensures the patency of the vitalside branch vessels 5. And then, the aneurysm opening of the aneurysm is blocked by expanding the inner-layer coveredstent 2 by using the balloon, and the inner-layer coveredstent 2 is partially sunk into the outer-layerbare stent 1 for fixing, so that the displacement of the inner-layer coveredstent 2 is avoided. The revascularization ensures that theaneurysm 3 is no longer in communication with the parent artery and also ensures that the vitalside branch vessels 5 are unobstructed.

For the intracranial saccular aneurysm, JDBM-2 magnesium alloy can be selected as thestent layer 2b of the inner-layer covered stent, the thickness is 20-50 mu m, and Zn-0.8Li zinc alloy can be selected as the outer-layerbare stent 1, and the thickness is 50-100 mu m.

Example 2: treatment of partial type E abdominal aortic aneurysm

Abdominal aortic aneurysms are classified into A, B, C, D and E-five types, with E-type abdominal aortic aneurysms being difficult to treat using existing stent grafts. Because the tumor mouth of the abdominal aortic aneurysm 9 is less than or equal to 1.5cm away from the lower edge of the opening of the renal artery 7, the normal blood vessel wall which is long enough is not available for fixing the existing covered stent. When such type E abdominal aortic aneurysm lesions do not involve the renal artery 7 and the abdominal aortic bifurcation, the present invention can be used for treatment. Because when adopting tectorial membrane double-deck support (1 and 2), whole inlayertectorial membrane support 2 all can be fixed on outernaked support 1, can fix inlayertectorial membrane support 2 under the prerequisite of guaranteeing that renal artery 7 is unblocked.

When treating such type E abdominal aortic aneurysm, as shown in fig. 8, the outerbare stent 1 is first released at the lesion site, and the outerbare stent 1 should span the ostium of the abdominal aortic aneurysm 9 and the opening of the renal artery 7. The angiography ensures the opening of the renal arteries 7. Because the abdominal aneurysm 9 is usually caused by atherosclerosis, the release of the outerbare stent 1 can compress fat, cholesterol, and the like, increase the diameter of the blood passage, reduce the influence of calcified parts and mural thrombus in the abdominal aorta 6 on the fixation of theinner stent graft 2, and provide a good environment for the release of theinner stent graft 2. Then, the balloon is used for expanding the inner-layer coveredstent 2 at the tumor opening of the abdominal aortic aneurysm 9, and the inner-layer coveredstent 2 is partially sunk into the outer-layerbare stent 1 and is firmly fixed, so that the displacement of the inner-layer coveredstent 2 is avoided. The revascularization ensures that theaneurysm 3 is no longer connected to the parent artery, while ensuring that the renal artery 7 and other important side branches are patent. Thestent layer 2b of the inner-layer covered stent can be Zn-0.8Mn-0.4Cu zinc alloy, the thickness is preferably 50-100 mu m, and the outer-layerbare stent 1 can be Fe-35Mn iron-based alloy, the thickness is 100-150 mu m. Ensuring adequate support and ordered degradation under the aorta.

Example 3: treating arterial wall rupture hemorrhage

As shown in fig. 9, when thelaceration 11 is closer to the importantside branch vessel 12 in case of artery wall rupture bleeding, the covered double-layer stent (1 and 2) can be selected for treatment, and the innercovered stent 2 and the outerbare stent 1 can be released in a whole manner through balloon dilatation. Not only can ensure the smoothness of the collateral blood vessels, but also can ensure the complete degradation of the whole stent finally. The naked support of outer 1 can provide the support for 11 endothelial cell adhesions of breach and growth, more can heal up fast, and the breach can be plugged up immediately to inlayer covered stent simultaneously, has hemostatic effect. Thestent layer 2b of the inner-layer covered stent can be made of high-molecular-weight L-polylactic acid with the thickness of 20-50 mu m, and the outer-layerbare stent 1 can be made of Zn-0.8Li zinc alloy with the thickness of 50-100 mu m. The molecular weight of thecoating film 2a is also appropriately reduced, so that thecoating film 2a is degraded as soon as possible after the laceration is healed.

Example 4: treating vertebral artery interlayer aneurysm

As shown in FIG. 10, the vertebro-arterials are classified by the posterior lower cerebellar artery (PICA) (16 and 19). When the dissecting aneurysm is located at the far end of the lower posterior cerebellar artery (16 and 19), the lesion does not affect the lower posterior cerebellar artery (16 and 19), so that the important collateral blood vessel can be retained and treated by using theinner stent graft 2 or the stent-assisted coil embolization method, etc., which will not be described in detail herein. When the dissected aneurysm is positioned at the proximal end of the lower posterior cerebellar artery (16 and 19), the pathological changes of the dissected aneurysm easily affect the lower posterior cerebellar artery (16 and 19), and even alaceration 21 may appear at the distal end of the lower posterior cerebellar artery, so that a blood flow path is formed in a false cavity of the dissected aneurysm, and the difficulty in judging a true false cavity is increased. In such cases, the present invention may be used to treat if the dissection affected area is free of tears in the posterior lower cerebral artery (16 and 19). Rely on the compliance of outernaked support 1 self and shorten the design of 2 lengths of inlayer covered stent, can adapt to crooked vertebral artery (15 and 18), simultaneously, the tectorial membrane double-deck support (1 and 2) can avoid sheltering from behind the cerebellum lower artery (16 and 19), can help the location and the release of inlayer coveredstent 2 again through outernaked support 1. In fig. 10, two different dissecting aneurysms (17 and 20) are shown simultaneously in both vertebral arteries (15 and 18), but this does not mean that both are occurring simultaneously, nor that the type of aneurysm corresponds to the left and right sides of the vertebral artery.

For the left vertebral interbredaneurysm 17 of fig. 10, the lesion affects the left cerebellar posteriorlower artery 16, but in the absence of other lacerations, the false lumen in the interbred aneurysm does not form a blood flow path, and the true lumen and the false lumen of the interbred region can be distinguished by angiography. To avoid thrombus and plaque sloughing into the cerebral circulation during subsequent procedures, a distalbrain protection device 22 is used to collect emboli generated during subsequent procedures. Next, the outerbare stent 1 is released in the true lumen of the left-sidedvertebral dissection aneurysm 17, the outerbare stent 1 spans the ostium and the ostium of the left-sided posterior cerebellarinferior artery 16, and the separated clips are laminated together, as shown in the left panel of fig. 11. Theinner stent graft 2 is then released with thelaceration 23 as the center, preventing blood from reentering the dissection. The inner stent graft need not cover the entire lesion area, avoiding obstruction of the blood flow path of the left cerebellum posteriorinferior artery 16. Finally, the distalbrain protection device 22 is recovered along with the collected emboli.

For the right sidevertebrobasilar aneurysm 20 of fig. 10, the lesion not only affects the right lateral cerebellar posteriorinferior artery 19, but also has alaceration 21 at the distal end of the right lateral cerebellar posteriorinferior artery 19. Therefore, after the outerbare stent 1 is released and the interlayer is pressed, two shortinner stent grafts 2 are needed to sequentially block the proximal and distal lacerations (24 and 25) to prevent the negative pressure in the tumor from causing blood to enter the interlayer again, as shown in the right diagram of fig. 11. Finally, the distalbrain protection device 22 is recovered along with the collected emboli.

In the subsequent degradation process, after thrombus, the laminated interlayer and the lacerations are self-healed in the tumor, thetectorial membrane 2a of the inner-layer covered stent is preferentially degraded, then thestent layer 2b of the inner-layer covered stent loses the supporting capability and continues to be degraded completely, and finally the outer-layerbare stent 1 loses the supporting capability until the degradation is complete. Thestent layer 2b of the inner-layer covered stent can be made of Zn-0.8Li zinc alloy with the thickness of 20-50 mu m, and the outer-layerbare stent 1 is also made of Zn-0.8Li zinc alloy with the thickness of 50-100 mu m.

Claims (3)

1. An orderly and completely degradable tectorial membrane double-layer stent is characterized by comprising an outer-layer naked stent and an inner-layer tectorial membrane stent, wherein the inner-layer tectorial membrane stent comprises a tectorial membrane and a stent layer; the stent part adopts biodegradable metal and alloy thereof or a biodegradable high polymer material, the expansion mode is a balloon expansion type, and the covering film adopts the biodegradable high polymer material; the outer-layer bare stent is released in advance, a false cavity of the dissected aneurysm can be pressed and a fixing place is provided for the inner-layer covered stent through a narrow section of a pathological change, the inner-layer covered stent is released later and fixed on the outer-layer stent through compressive stress, and the release position, the length and the number of the stent can be determined according to the rupture conditions of the aneurysm neck and the dissected aneurysm, so that important side branch blood vessels are avoided and are guaranteed to be unblocked; the degradation of the covered double-layer stent is orderly, and in the degradation process, the covered membrane is kept complete before the organization in the aneurysm and the healing of the vascular laceration; when the tectorial membrane is completely degraded within half a year to 1 year, the support capability of the stent layer of the inner layer tectorial membrane stent is not lost; when the stent layer of the inner-layer covered stent is completely degraded within 1-3 years, the supporting capability of the outer-layer bare stent is not lost, and finally the outer-layer bare stent is completely degraded within 3-5 years;

the selection principle of the bracket material is as follows: the initial tensile strength is higher than 300MPa, the yield strength is higher than 200MPa, and the elongation is greater than 20%; in the first six months of the degradation process, the yield strength of the outer layer bare stent material is higher than 150MPa, the yield strength of the inner layer stent material is higher than 100MPa, and degradation products are nontoxic; the inner and outer layer brackets are made of Mg and alloy thereof, Zn and alloy thereof, Fe and alloy thereof and polylactic acid material; the stent layers of the outer bare stent and the inner covered stent are made of the same or different materials; when the stent is made of a heterogeneous material, the degradation rate of the inner-layer stent material is higher than that of the outer-layer bare stent material; if the inner layer stent material is made of metal materials, the corrosion potential of the inner layer stent material is lower than that of the outer layer bare stent material;

the coverage rate of the outer bare stent is 10% -20%, the coverage rate of the inner covered stent is 20% -30%, and the coverage rate of the outer stent is lower than that of the inner stent, so that the smoothness of important collateral blood vessels is guaranteed.

2. The covered double-layer stent according to claim 1, wherein the covering material is a biodegradable polymer material, selected from polylactic acid (PLA), poly-L-lactic acid (PLLA), polycaprolactone and polyglycolic acid, and is degraded within half a year to 1 year by regulating and controlling the tissue thereof; meanwhile, the tectorial membrane of the inner-layer tectorial membrane stent is connected with the stent layer in a heat seal or stamping way.

3. The covered double-layered stent according to claim 1, wherein the thickness of the outer bare stent is 50 to 150 μm, the thickness of the inner covered stent is 20 to 80 μm, and the thickness of the outer stent is greater than that of the inner stent.

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