CN107811728B

CN107811728B - Endovascular prosthesis

Info

Publication number: CN107811728B
Application number: CN201710959607.6A
Authority: CN
Inventors: 陈树国; 党军; 李峰
Original assignee: Shanghai Hongchuang Medical Technologies Co ltd; Suzhou Hengruidisheng Medical Technology Co ltd
Current assignee: Shanghai Hongchuang Medical Technologies Co ltd; Suzhou Hengruidisheng Medical Technology Co ltd
Priority date: 2017-10-16
Filing date: 2017-10-16
Publication date: 2024-06-21
Anticipated expiration: 2037-10-16
Also published as: CN107811728A

Abstract

The invention discloses an endovascular prosthesis, which comprises an i-layer tubular vascular stent, wherein i is more than or equal to 2 and less than or equal to 8, and is used for treating aortic dissection and aneurysm lesions, in particular to ascending aortic dissection; the tubular vascular stent is divided into a dense mesh woven stent and a sparse mesh woven stent, wherein the dense mesh woven stent has larger mesh density and the sparse mesh woven stent has smaller mesh density; the number of the dense net woven brackets is m, wherein m is more than or equal to 1 and less than or equal to 4; the number of the open mesh woven brackets is n, wherein n is more than or equal to 1 and less than or equal to 4; and i=m+n; the dense mesh braided stent and the open mesh braided stent are coaxially stacked together in the circumferential direction for cooperatively supporting a blood vessel, and mutually restricting the axial extension or shortening deformation of the stent. The invention can effectively treat aortic dissection through stent intervention operation, in particular to treat aortic dissection or aneurysm which cannot be clinically treated at present.

Description

Endovascular prosthesis

Technical Field

The present invention relates to the field of medical devices, and more particularly to an endovascular prosthesis.

Background

The thoracic aortic dissection is not a true aneurysm or a false aneurysm, but is a damage to an intima and a medial layer of an artery caused by various reasons, blood in an aortic cavity enters the medial layer of the aorta along the torn intima of the artery, hematoma is formed in the medial layer, the medial layer is torn and separated, the aortic wall is peeled into two layers, and the peeled part gradually extends and expands towards the proximal end and the distal end of the aorta under the impact of blood flow, so that an aortic blood flow false cavity is formed. A different range of medial separation distensions is formed, known as aortic dissection or aortic dissection.

Aortic dissection is a common special type of thoracic aortic aneurysm, the etiology of which is mainly: hypertension and arteriosclerosis, connective tissue diseases and Ma Fanzeng syndrome, congenital aortic valve stenosis, two-leaf aortic valve malformations, congenital aortic stenosis, etc. The aortic dissection is harmful in that once the false cavity is formed, the false cavity becomes an irregular bomb, and the false cavity rupture or the formed aneurysm rupture is easy to cause massive hemorrhage, interrupts the blood flow supply of important branches of the aorta, causes serious ischemia function loss of important viscera, and causes serious complications and death.

The thoracic aortic dissection most often begins with the ascending aorta above the aortic valve, followed by the aortic isthmus, but can also occur in the aortic arch and elsewhere in the aorta. DeBakey classifies aortic dissection into three types, depending on the scope of pathology and pathology.

Type I: the aortic wall dissection is initiated at the root of the ascending aorta, the rupture of the intima generally initiates at the anterior wall of the proximal end of the ascending aorta, extending distally to the descending aorta, but may also initiate at the aortic arch or even at the thoracic descending aorta, retrograde separation to the root of the aorta and distally to the rest of the aorta. These patients often experience a loss of support of the valve due to expansion of the aortic annulus or dissection of the annulus, resulting in an insufficiency of the aortic valve.

Type II: the site of aortic wall dissection is limited to the ascending aorta. A common feature is a transverse tear in the anterior intima wall of the aortic valve, and dissection generally terminates at the proximal end of the innominate aortic initiator, sometimes also involving the aortic arch. Such patients also often incorporate aortic insufficiency.

Type III: aortic wall dissection begins distally of the left subclavian artery opening and extends to a certain extent distally of the aorta. If the lesion is limited to the thoracic descending aorta, the lesion is called IIIa type; however, most patient's dissection lesions extend under the diaphragm, affecting the abdominal aorta and even the iliac arteries, called type IIIb.

The thoracic aortic dissection can be divided into acute and chronic types according to onset time, wherein the acute dissection refers to the aortic dissection occurring within 2 weeks and is called chronic aortic dissection after 2 weeks of onset, and the clinical manifestations and prognosis of the two are greatly different. The death rate of the acute aortic dissection in 48 hours can reach 36 to 72 percent due to aneurysm rupture, acute cardiac tamponade and the like, and the death rate in 2 weeks is 57 to 89 percent. While in the chronic phase, the deaths due to rupture are significantly reduced, but 90% of patients die from arterial dissection rupture within half a year of onset.

The most common and important symptom of acute chest aortic dissection is sudden tear-like severe pain, and patients often feel moribund. The pain position of the A-shaped interlayer is behind the sternum and is radioactive; the pain location of the B-type interlayer is in the chest and back. Depending on the extent of dissection, the painful area may extend to the abdomen, lower abdomen, etc. Some patients may exhibit acute left heart failure due to the concurrent acute insufficiency of the aortic valve. Other symptoms include syncope, dyspnea, etc. And when acutely ruptured concurrently, the patient will die within minutes.

At present, various self-expansion tectorial membrane stents have been developed for the descending aortic dissection of the DeBakey III type for interventional therapy and have good effects. The basic principle is that the covered stent is compressed and then loaded on a conveying system, is conveyed to a vascular lesion position from a femoral artery or an iliac artery at the far end and then released, the stent is opened in a vascular cavity and is tightly attached to the inner wall of an aorta by utilizing the self-expansion characteristic of the stent, and the covered film on the surface of the stent is used for isolating and sealing an aneurysm or an interlayer. Thereby achieving the purpose of treatment. This technique has been widely used at present.

However, these products can only be applied to the descending thoracic aorta and require a stent anchoring zone of no less than 15mm. Such as the thoracic aorta, require a tumor or dissection at least 15-20mm from the left subclavian artery. For patients with the interlayer or aneurysm affecting the ascending aorta, as the ascending aorta is relatively short and thick, and the coronary artery opening for supplying blood to the heart is arranged at the near-heart end, the brachiocephalic trunk opening for supplying blood to the brain, namely the right upper limb, the left common carotid artery and the left subclavian artery are arranged at the distal end, the application of the existing covered stent in the interlayer treatment of the ascending aorta is limited by the physiological morphological structure, and the stent is difficult to realize stable anchoring in the vascular cavity of the ascending aorta. Once the stent is displaced loose, endoleak occurs, resulting in failure of the procedure. At present, no mature and available interventional treatment technology exists, and only conventional open chest operation can be adopted for artificial blood vessel replacement.

To solve the above-mentioned problems, CN201120022195.1 patent has proposed to prevent the occurrence of blood leakage or rupture of an aneurysm by filling the neck of the tumor to anchor the stent graft, resulting from loose displacement of the insulating graft within the lumen of the blood vessel. This patent proposes a new idea of anchoring, however anchoring the stent graft by filling the tumor neck does not immediately result in anchoring the stent graft, and the anchoring strength depends on the physiological structure of the tumor neck, and the anchoring strength and efficiency are limited. The CN201480041652.8 patent discloses a multi-component stent graft for treating aneurysms or arterial dissection of the ascending aorta. The stent is placed in the ascending aorta, the aortic sinus, and the left and right coronary arteries. Anchoring of the ascending aortic stent is provided by placement of the branch stent into the left and right coronary arteries. Although the left and right coronary arteries can be anchored at a certain ratio, the left and right coronary arteries have too small sizes, the diameter is only 4-6 mm, the branch stent cannot be too long, and the diameter of the ascending aorta reaches more than 40mm, so that the problem of insufficient anchoring effect still exists.

Therefore, there is a great clinical need to develop a new type of endovascular graft to address this problem.

Disclosure of Invention

The present invention aims to provide an endovascular prosthesis consisting of a combination of a plurality of braided stents of different braiding densities for the treatment of aortic dissection and aneurysms, in particular aortic dissection and aortic arch dissection, and aortic dissection.

The invention provides an endovascular prosthesis, in particular, the endovascular prosthesis comprises an i-layer tubular vascular stent, wherein i is more than or equal to 2 and less than or equal to 8, and the endovascular prosthesis is used for treating aortic dissection and aneurysm lesions, in particular, ascending aortic dissection and abdominal aortic dissection; the tubular vascular stent is divided into a dense mesh woven stent and an open mesh woven stent, wherein the dense mesh woven stent has larger mesh density, and the open mesh woven stent has smaller mesh density; the number of the dense net woven brackets is m, wherein m is more than or equal to 1 and less than or equal to 4; the number of the open mesh woven brackets is n, wherein n is more than or equal to 1 and less than or equal to 4; and i=m+n; the dense mesh braided stent and the open mesh braided stent are coaxially stacked together along the circumferential direction for cooperatively supporting a blood vessel and mutually limiting the axial extension or shortening deformation of the stent.

In another preferred embodiment, the endovascular prosthesis comprises an inner layer and an outer layer, wherein the outer layer is the open mesh braided stent, the inner layer is the close mesh braided stent, and the mesh density of the braided stent increases from the outer layer to the inner layer in sequence, wherein m is more than or equal to 1 and less than or equal to 4, and n is more than or equal to 1 and less than or equal to 2; and the two ends of the dense net woven support are provided with flaring designs, the flaring angles are 5-30 degrees, and the flaring lengths are 5-30mm so as to be tightly attached to the outer layer of the open net woven support.

Preferably, the braiding angle of the dense mesh braided stent is not equal to that of the open mesh braided stent, and the braiding angles of two layers of stents adjacent to each other are not equal to each other.

In another preferred embodiment, the braiding angles of two adjacent layers of stents differ by at least 5 °, preferably 15-60 °, so that adjacent braiding grids are superimposed to each other to create smaller meshes, thereby achieving an effective isolation and closure of the blood flow in the prosthetic space.

Preferably, the mesh braiding angle of the tubular vascular stent gradually descends from the outer layer to the inner layer, the braiding angle of the open mesh braiding stent of the outer layer is larger, effective support of a true lumen of a blood vessel is achieved, and the braiding angle of the close mesh braiding stent of the inner layer is smaller, so that more head braiding is achieved.

In another preferred embodiment, the endovascular prosthesis comprises an outer layer, an inner layer and an intermediate layer, wherein the intermediate layer is the dense mesh braided stent, the outer layer and the inner layer are open mesh braided stents, the mesh density of the braided stent decreases layer by layer from the intermediate layer to the outer layer or to the inner layer, and the mesh density of the intermediate layer is the greatest; the number of the middle layers is 1-3, and the number of the outer layers and the number of the inner layers are 1-2.

Preferably, the braiding angle of the dense mesh braided stent is not equal to that of the open mesh braided stent, and the braiding angles of two adjacent layers of stents are not equal to each other.

In another preferred example, the endovascular prosthesis comprises an inner layer and an outer layer, wherein the outer layer is the dense mesh woven stent, the inner layer is the open mesh woven stent, and the mesh density of the woven stent decreases sequentially from the outer layer to the inner layer, wherein 1.ltoreq.m.ltoreq.4, and 1.ltoreq.n.ltoreq.2.

Preferably, the braiding angle of the dense mesh braided stent is close to that of the open mesh braided stent, and the braiding angles of two adjacent layers of stents are not more than 5 degrees, so that the multi-layer tubular vascular stent has the same shrinkage rate when being loaded and compressed, and is smoothly loaded on the surface of a conveying system and integrally released.

In another preferred embodiment, the endovascular prosthesis further comprises a delivery system for delivering the tubular vascular stent to a target vascular lesion site.

In another preferred embodiment, each layer of the tubular vascular stent is assembled by the delivery system alone, pushed by the delivery system in sequence and released layer by layer to the target vascular lesion site to form a multi-layer stent.

In another preferred embodiment, each layer of the tubular vascular stent is serially connected to the delivery system inner tube.

In another preferred embodiment, the tubular vascular stent is integrally loaded on the delivery system and released by the delivery system layer by layer to the target vascular lesion site.

In another preferred embodiment, the tubular vascular stent is of conical design.

In another preferred embodiment, the dense mesh braided stent is covered with a coating.

In another preferred embodiment, the open mesh braided stent is a closed loop braided stent.

In another preferred embodiment, the multi-layered tubular vascular stent should have a greater length after release than the dense mesh braided stent during delivery and release, and the open mesh braided stent should cover the length of the dense mesh braided stent.

In another preferred embodiment, the conveying system is provided with a developing ring and/or a developing positioning device of the support wire, and the relative positions of the open mesh woven support and the close mesh woven support are controlled through the developing ring and the developing positioning device of the support wire.

In general, dense mesh woven stents should cover the dissection and aneurysm lesion sites to achieve occlusion isolation of the dissection and aneurysm, while open mesh woven stents should extend to aortic arch sites in addition to covering the dissection and aneurysm lesion sites to provide better support and anchoring.

In another preferred example, the braided wires of the open mesh braided stent are nickel-titanium alloy wires, or platinum core nickel-titanium alloy wires.

In another preferred embodiment, the open mesh woven stent has a mesh weave density of no more than 30.

In another preferred embodiment, the mesh area of the open mesh woven stent is no less than 1mm ², preferably greater than 2mm ².

In another preferred embodiment, the open mesh braided stent has a stent wire diameter of not less than 0.1mm, preferably 0.15-0.3mm.

In another preferred embodiment, the open mesh braided stent has a braiding angle of not less than 90 °, preferably 120-150 °.

In another preferred embodiment, the open mesh braided stent has a high radial support force for providing support to the vessel and opening up the true lumen blood flow.

In another preferred embodiment, the open mesh braided stent is braided with monofilaments for achieving closed loop braiding of the open mesh braided stent ends.

In another preferred embodiment, the head and tail ends of the braided wires of the open mesh braided stent are treated by laser welding

In another preferred embodiment, the laser welding process comprises direct welding or welding with a connecting structure.

In another preferred embodiment, the connection structure comprises a welded tube, a welded tab, a welded wire, a welded joint, or the like.

In another preferred embodiment, the dense mesh braided stent is an open loop braided stent.

In another preferred example, the braided wires of the dense mesh braided stent are nickel-titanium alloy wires, or platinum core nickel-titanium alloy wires.

In another preferred embodiment, the mesh weave density of the close-woven stent is not less than 30.

In another preferred embodiment, the mesh area of the close-woven stent is no more than 1mm ², preferably less than 0.3mm ².

In another preferred embodiment, the wire diameter of the dense mesh woven stent is no more than 0.1mm, preferably 0.05-0.08mm.

In another preferred embodiment, the tight mesh braided stent has a braiding angle of 75-135 °.

The dense mesh woven stent has the functions of isolating blood flow in the interlayer false cavity, changing blood flow velocity in the false cavity and increasing blood flow velocity in the true cavity.

In another preferred embodiment, in a multilayered tubular vascular stent, the mesh area of the stent after multilayered combination of the dense mesh woven stent and the open mesh woven stent should be less than 0.3mm ², preferably less than 0.1mm ².

In another preferred embodiment, the metal coverage of the tubular vascular stent at the surface of the vessel is not less than 10%, preferably 20-30%.

In another preferred embodiment, the tubular vascular stent is preferably a self-expanding metallic stent.

In another preferred embodiment, the outer diameter of the inner stent should be not smaller than the inner diameter of the outer stent, in particular, the outer diameter of the inner stent should be greater than 5-40%, preferably 10-30%, of the inner diameter of the outer stent so that the inner stent can be closely attached to the inner surface of the outer stent without displacement. The inner and outer layers are defined herein in terms of the mutual position of adjacent two-layer tubular vascular stents; the outer diameter and the inner diameter of the stent refer to the outer diameter and the inner diameter of the tubular vascular stent in a natural state without external force constraint in normal saline at 37 ℃.

In another preferred embodiment, in a multilayered tubular vascular stent, the stent ends of the inner and/or middle layer have a flaring design so that the stent is tightly attached to the outer stent without shifting, preferably with a flaring angle of 5-30 deg., and a flaring length of 5-30mm.

In another preferred embodiment, since the vessel diameter tapers from the proximal end to the distal end, it is desirable that the stent have a tapered design so that the tubular vessel stent can be firmly anchored to the inner surface of the vessel without displacement; preferably, the tubular vascular stent is of conical design, i.e. the diameter of the proximal end of the stent is larger than the diameter of the distal end of the stent, in particular the proximal diameter should be at least 3mm, preferably more than 5-10mm, larger than the distal diameter. The proximal end of the stent means that after the stent is implanted into a blood vessel, the portion of the stent close to the heart is the proximal end of the stent, and the portion of the stent far away from the heart is the distal end of the stent.

In another preferred embodiment, the head end braiding wires of the dense mesh braided stent are in an open, unsealed treatment state.

In another preferred embodiment, both ends of the dense mesh woven stent are covered with a coating.

In another preferred embodiment, the coating is a biocompatible non-degradable polymeric material, such as expanded polytetrafluoroethylene, PET coating, or an absorbable polymeric material, such as polylactic acid, polycaprolactone, polylactic acid-caprolactone copolymer, and the like.

In another preferred embodiment, the head end of the tubular vascular stent is coated by a coating, so that the braided wires of the head end of the tubular vascular stent are prevented from stimulating and proliferating vascular endothelium.

In another preferred embodiment, the length of the coating is 5-20mm.

In another preferred embodiment, the surface of the mesh-braided stent carries an active substance for promoting endothelial growth, such as hematopoietic stem cells, CD34 antibodies, etc., so that the mesh-braided stent can be rapidly endothelialized to realize the isolated blocking effect on the interlayer breach.

In another preferred embodiment, the open mesh woven stent has a length that is greater than the length of the close mesh woven stent. In the thoracic aorta, the length of the dense mesh braided stent is used for covering the lacerations of the interlayer to block the inlet and the outlet of the blood flow of the false cavity, and the length of the open mesh braided stent is required to be further prolonged besides the length of the dense mesh braided stent, so that the anchoring effect on the multilayer tubular vascular stent is realized. In particular, for ascending aortic dissection and aneurysm treatment, the open mesh braided stent may extend from the ascending aorta to the aortic arch, and for descending aortic dissection and aneurysm treatment, the open mesh braided stent may extend from the descending aorta to the aortic arch and abdominal aorta. The open mesh braided stent is prolonged to the aortic arch part, so that the multilayer tubular vascular stent at the ascending aorta is prevented from being flushed to the aortic arch part by blood flow. Meanwhile, as the mesh density of the open mesh woven stent is smaller and the mesh area is larger, the branch blood flow of the aortic arch part can not be blocked.

In another preferred embodiment, in a multilayered tubular vascular stent, the surface of the dense mesh braided stent, particularly at its central region, may be partially covered with a length of polymer film.

In another preferred example, the absorbable polymer film material is a racemic polylactic acid-polycaprolactone copolymer, polylactic acid-polyglycolic acid-polycaprolactone copolymer, or blends thereof, or the like.

In another preferred embodiment, the absorbable polymer film is applied to the dense mesh woven stent by spraying, coating, electrospinning, or the like.

In another preferred embodiment, the degradation time of the absorbable polymer film is 3 to 12 months, preferably 3 to 6 months.

In another preferred embodiment, the thickness of the absorbable polymer film is less than 100 μm; preferably below 50 μm; more preferably, or less than 30 μm.

In another preferred embodiment, the length of the absorbable polymer film is 5-30mm less than the length of the dense mesh woven stent.

In another preferred embodiment, the absorbable polymer film has good extensibility properties.

The absorbable polymer film has the main function of blocking the interlayer breach blood flow, and in the endothelialization process of the stent, the film is gradually degraded without influencing the coverage of the stent by the endothelium, so that the film does not adopt a non-degradable polymer film, such as expanded polytetrafluoroethylene and the like, and the existing clinical literature shows that the aortic film stent is difficult to endothelialize due to the surface coverage of a layer of non-degradable film material on the surface of the stent.

It is understood that within the scope of the present invention, the above-described technical features of the present invention and technical features specifically described below (e.g., in the examples) may be combined with each other to constitute new or preferred technical solutions. And are limited to a space, and are not described in detail herein.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1a is a front view of a mesh-dense woven stent in one example of the invention.

Fig. 1b is a perspective view of a mesh-dense woven stent in one example of the invention.

Fig. 2a is a front view of a tight mesh braided stent of flared design in one example of the invention.

Fig. 2b is a perspective view of a tight mesh braided stent of flared design in one example of the invention.

Fig. 3a is a front view of a open mesh woven stent in one example of the invention.

Fig. 3b is a perspective view of a open mesh woven stent in one example of the invention.

Fig. 4 is a schematic diagram of mesh staggering after a combination of a dense mesh woven stent and a open mesh woven stent in one example of the invention.

Fig. 5a is a front view of a dense mesh braided stent with an intermediate coating in one example of the invention.

Fig. 5b is a perspective view of a dense mesh braided stent with an intermediate coating in one example of the invention.

Fig. 6a is a front view of a two-end coated, dense mesh braided stent in accordance with one embodiment of the present invention.

Fig. 6b is a perspective view of a two-end coated, dense mesh braided stent in one example of the invention.

In the drawings, each is indicated as follows:

1-dense net braiding support;

2-open mesh woven stent.

Detailed Description

The inventor of the present invention has developed an endovascular prosthesis for the first time through extensive and intensive studies, which is composed of a plurality of knitted stents with different knitting densities, for solving the problem that the existing covered stent cannot effectively treat aortic dissection, in particular, ascending aortic dissection, through a large number of screens.

Terminology

As used herein, the term "mesh braid density" refers to the number of meshes over a 1 inch length of the stent in the axial direction.

As used herein, the term "braid angle" refers to the angle formed by the interdigitated braid wires in the axial direction.

The present invention provides an endovascular prosthesis, which is an endovascular prosthesis with a specific structure.

Typically, the endovascular prosthesis comprises an i-layer tubular stent, wherein i is more than or equal to 2 and less than or equal to 8, and the i-layer tubular stent is used for treating aortic dissection and aneurysm lesions, particularly ascending aortic dissection, and the tubular stent is divided into a dense mesh woven stent and an open mesh woven stent, the mesh density of the dense mesh woven stent is higher, and the mesh density of the open mesh woven stent is lower; the number of the dense net woven brackets is m, wherein m is more than or equal to 1 and less than or equal to 4; the number of the open mesh woven brackets is n, wherein n is more than or equal to 1 and less than or equal to 4; and i=m+n; the dense mesh braided stent and the open mesh braided stent are coaxially stacked together in the circumferential direction for cooperatively supporting a blood vessel, and mutually restricting the axial extension or shortening deformation of the stent.

A multilayer tubular vascular stent system is formed by combining 2-6 layers of stents, each layer of stent is independently assembled by a conveying system, and the stents are released to a target vascular lesion position layer by the conveying system to form a multilayer stent; or the multiple layers of stents are integrally loaded on a delivery system and released to the target vascular lesion site layer by the delivery system.

A multi-layer tubular vascular stent system is formed by combining 2-6 layers of stents, wherein the outer diameter of each layer of stent is at least more than 10 mm. Each layer of stent is connected in series on an inner tube of a conveying system, and is sequentially pushed by the conveying system to release each layer of stent at a target vascular lesion position to form a multi-layer stent; or the multiple layers of stents are integrally loaded on a delivery system and released to the target vascular lesion site layer by the delivery system.

A multi-layer tubular vascular stent system is formed by combining 2-6 layers of stents, wherein the multi-layer stents are integrally loaded on a conveying system and released to a target vascular lesion position layer by the conveying system.

The main advantages of the invention include:

(a) Multiple tubular vascular stents may be delivered by one delivery system; the use cost of the conveying system is saved;

(b) The multiple tubular vascular stents are stacked and combined to generate a small mesh area, so that the blood flow of a false cavity can be effectively reduced, and the effect of isolating and blocking the blood flow of the false cavity is gradually realized;

(c) The braided stent has good flexibility and can smoothly span the aortic arch part;

(d) Because each tubular vascular stent can be independently delivered, the stent delivery system has a small passing outer diameter, the passing outer diameter of the stent delivery system can be lower than 18F (1F is approximately equal to 0.33mm in diameter and 18F is approximately 6mm in diameter), puncture treatment can be performed through femoral artery, subclavian artery and the like, and delivery is performed without cutting off the femoral iliac artery;

(e) The multi-layer stent can not block aortic arch blood flow, the risk of cerebral thrombosis is avoided, the combined stent of the two has good stent anchoring effect, the stent has no displacement risk, and the branch blood flow of the aortic arch is still kept smooth;

(f) The support with the longest two ends is a sparse mesh woven closed-loop support, namely the woven mesh density of the support is sparse, the mesh is larger, meanwhile, the head end of the support is sealed and continuously woven, the head end of the woven wire is not exposed outside the external vascular wall, and vascular endothelial hyperplasia cannot be stimulated;

(g) The two ends of the dense net woven stent are covered by the covering film, so that vascular endothelial proliferation can not be stimulated;

(h) The middle of the dense net woven stent is covered by a covering film, so that aortic dissection can be better isolated and blocked;

(i) The surface of the dense net woven stent carries active substances for promoting endothelial growth, such as hematopoietic stem cells, CD34 antibodies and the like, so that the dense net woven stent can be rapidly endothelialized, and the isolated blocking effect on interlayer openings is realized;

(j) The multi-layer combined support has good supporting force and flexibility.

Therefore, the multilayer tubular vascular stent can simulate a vascular multilayer composite hollow pipeline structure, can effectively treat aortic dissection through stent intervention operation, and particularly treat aortic dissection or aneurysm which cannot be clinically treated at present.

The invention will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. Furthermore, the drawings are schematic representations, and thus the apparatus and device of the present invention are not limited by the dimensions or proportions of the schematic representations.

It should be noted that in the claims and the description of this patent, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

Example 1

The tubular vascular stent of the embodiment adopts a three-layer stent design, the outer layer is a layer of open-net closed-loop stent, and the inner layer is a two-layer close-net woven stent. Fig. 1a and 1b show a dense mesh woven stent of the present embodiment, and fig. 3a and 3b show an open mesh woven stent of the present embodiment. The support wire of the dense mesh braided support is a platinum core nickel-titanium alloy wire so as to provide better developability. The diameters of stent wires of the dense mesh braided stent are all 0.075mm, the mesh area is 0.5mm ², the braiding angle is 120 degrees, the outer diameter of the proximal end is 45mm, the outer diameter of the distal end is 40mm, and the length is 60mm. The diameter of the support wire of the open-mesh closed-loop braided support is 0.15mm, the mesh area is 2mm ², the braiding angle is 150 degrees, the outer diameter of the proximal end is 40mm, the outer diameter of the distal end is 35mm, and the length is 100mm.

When the tubular vascular stent of the embodiment is used for treating DeBakey III type lesions, each tubular vascular stent is independently assembled by a conveying system, and the tubular vascular stents are released to the target vascular lesion position layer by the conveying system to form a multi-layer stent. By means of the visualization ring of the delivery system and the visualization positioning of the stent wire, the open mesh braided stent is first released to the aortic arch and descending aortic arch position, covering the length of the sandwich lesion, and extending to the aortic arch position. After the open mesh braided stent is released, the close mesh braided stent is released on the inner surface of the open mesh braided stent, the close mesh braided stent is controlled to completely cover the pathological change position of the interlayer by means of the development positioning of the development ring and the stent wire of the conveying system, and the proximal end of the close mesh braided stent can partially cover the left subclavian artery so as to realize the full isolated coverage of the interlayer inlet. But the proximal end of the dense mesh braided stent may not exceed the proximal end of the open mesh braided stent. After the dense net woven support is released, as the nominal diameter of the dense net woven support is larger than that of the open net woven support, and the head ends of the dense net woven support are scattered and woven, woven wires at the two ends are embedded into meshes of the open net woven support, the dense net woven support can be tightly attached to the inner surface of the open net woven support without displacement. Wherein, the mesh staggered schematic diagram of the combination of the dense mesh woven stent and the open mesh woven stent is shown in fig. 4.

After the stent is released, the blood flow velocity at the inlet of the interlayer is slowed down due to the isolation and blocking effects of the dense mesh woven stent, so that thrombus solidification is gradually formed. The interlayer is gradually blocked. Simultaneously, the COF force of the stent induces vascular endothelial tissue to grow on the surface of the stent rod and cover the surface of the stent, and the surface of the stent is wrapped to form an endothelial layer, so that the isolation interlayer is completely blocked.

Example 2

The tubular vascular stent of this embodiment is similar to embodiment 1, except that the two-layer mesh-braided stent of this embodiment is of flaring design. Fig. 2a and 2b show a dense mesh braided stent of the present embodiment, which has a stent wire of 0.05mm, a mesh area of 0.3mm ², and a braiding angle of 90 °; the end part is subjected to flaring treatment, the flaring angle is 15 degrees, and the flaring length is 10mm; the outer diameter of the proximal end is 48mm, and the outer diameter of the distal end is 43mm (both are non-flared outer diameters); the length is 50mm. The loading and release of the tubular vascular stent were similar to those of example 1.

Compared with the embodiment 1, the treatment effect of the embodiment is the same as that of the embodiment 1, and the dense mesh woven stent of the embodiment 1 is not flared, so that the dense mesh woven stent of the embodiment can be more closely attached to the inner surface of the open mesh woven stent without displacement.

Example 3

The stent wire of the tubular vascular stent of this embodiment is nickel titanium wire, and the stent adopts four-layer stent design, the tubular vascular stent of this embodiment includes outer, inlayer and intermediate level, wherein, the intermediate level is two-layer close net braided stent, outer and inlayer have one deck to dredge net braided stent respectively, and close net braided stent's braiding angle is unequal to the braiding angle of dredging net braided stent, the braiding angle of adjacent two-layer support also is unequal each other, the braiding angle of adjacent two-layer support looks 15-60, so that adjacent braiding net superposes each other and produces less mesh, realize the effectual isolated closure effect to the false chamber blood flow, in addition, as shown in fig. 5a and 5b, there is one deck tectorial membrane in the intermediate color of close net braided stent, the length of tectorial membrane is 25mm for realizing better shutoff isolation effect. The coating is an absorbable polymer film, and can be coated on the dense net woven bracket by adopting the processes of spraying, coating, electrostatic spinning and the like. The degradation time of the absorbable polymer film is 3 to 6 months, and at the same time, the absorbable polymer film should have good extensibility characteristics and can generate extensibility deformation along with the stent. The absorbable polymer film has the main function of blocking the interlayer breach blood flow, and the film is gradually degraded in the endothelialization process of the stent without affecting the coverage of the stent by the endothelium.

The loading and release of the tubular vascular stent are similar to those of the embodiment 1, wherein the two layers of the dense mesh woven stent in the middle layer can be integrally conveyed through a conveying system, namely, the tubular vascular stent in the embodiment can be integrally conveyed and layered conveyed, and the two layers of the dense mesh woven stent and the conveying system are released to the target vascular lesion position in a combined mode and are combined into the multilayer stent. The treatment effect of this example is the same as that of example 1.

Example 4

The stent wire of the tubular vascular stent of the embodiment is nickel titanium wire, the stent adopts a two-layer stent design, the tubular vascular stent of the embodiment comprises an outer layer and an inner layer, wherein the outer layer is a dense mesh woven stent, and the inner layer is an open mesh woven stent; the inner and outer woven brackets are integrally conveyed by adopting the same conveying system; the braiding angles of the dense net braiding support and the open net braiding support are 135 degrees, so that different support shortening caused by compression of the two layers of braiding supports is avoided; in addition, as shown in fig. 6a and 6b, both ends of the dense mesh woven stent are coated with a coating, and the lengths of the coating at both ends are 10mm. The coating film is made of an absorbable polymer material with good biocompatibility, such as polylactic acid, polycaprolactone, polylactic acid-caprolactone copolymer and the like; the design of covering film and cladding of the head end of the dense net woven stent avoids the stimulation and proliferation of open woven wires at the head end of the stent to vascular endothelium. The open mesh braided stent is of a conical design, namely, the diameter of the proximal end of the stent is larger than that of the distal end of the stent so as to adapt to gradual reduction of the diameter of a blood vessel from the proximal end to the distal end, and further, the tubular vascular stent can be firmly anchored on the inner surface of the blood vessel without displacement. In order to avoid the displacement of the dense mesh woven stent relative to the open mesh woven stent after release, the dense mesh woven stent is preferably sewn on the outer surface of the open mesh woven stent by adopting a suture.

When the tubular vascular stent of the embodiment is used for treating DeBakey II type lesions, a dense mesh braided stent which is suitable for the lesion length and a sparse mesh braided stent which can extend to the aortic arch are selected according to the lengths of the interlayer and the aneurysm. The stent is released by the delivery system to the target vascular lesion site by means of the visualization ring of the delivery system and the visualization positioning of the stent wire. The dense mesh woven stent covers the ascending aortic dissection and can partially cover the brachiocephalic trunk artery so as to realize the full isolated coverage of the dissection breach. The open mesh braided stent extends to the aortic arch to enhance the anchoring effect of the stent. The treatment effect of this example is the same as that of example 1.

All documents mentioned in this disclosure are incorporated by reference in this disclosure as if each were individually incorporated by reference. Further, it will be appreciated that various changes and modifications may be made by those skilled in the art after reading the above teachings, and such equivalents are intended to fall within the scope of the application as defined in the appended claims.

Claims

1. An endovascular prosthesis comprising a 3-layered tubular stent for treating aortic dissection;

the tubular vascular stent is divided into a dense mesh woven stent and an open mesh woven stent, wherein the dense mesh woven stent has larger mesh density, and the open mesh woven stent has smaller mesh density;

the dense mesh woven stent and the open mesh woven stent are coaxially stacked together along the circumferential direction and are used for cooperatively supporting a blood vessel and mutually limiting axial extension or shortening deformation;

In the 3 layers of the tubular vascular stent, the outer layer is a layer of open-net closed-loop stent, the inner layer is a two-layer close-net woven stent, and both ends of the two-layer close-net woven stent are provided with flaring designs, so that the inner layer is tightly attached to the outer layer, no displacement occurs, the flaring angle is 5-30 degrees, and the flaring length is 5-30mm;

The endovascular prosthesis further comprises a delivery system for delivering the tubular vascular stent to a target vascular lesion site; each layer of the tubular vascular stent is independently conveyed by the conveying system, sequentially pushed by the conveying system and released to the target vascular lesion position layer by layer to be combined into a multi-layer stent;

The proximal end of the dense mesh braided stent cannot exceed the proximal end of the open mesh braided stent; after the dense mesh woven stent is released, as the diameter of the dense mesh woven stent is larger than that of the open mesh woven stent, and the head end of the dense mesh woven stent is in scattered weaving, the weaving wires at the two ends are embedded into the meshes of the open mesh woven stent, so that the dense mesh woven stent is closely attached to the inner surface of the open mesh woven stent without displacement;

The weaving angles of two adjacent layers of brackets differ by at least 5 degrees, so that adjacent weaving grids are overlapped with each other to generate smaller meshes, and the effective isolation and sealing effects on the blood flow of the false cavity are realized;

The mesh braiding angle of the tubular vascular stent gradually descends from the outer layer to the inner layer, the braiding angle of the open mesh braiding stent of the outer layer is larger, effective support of a blood vessel true cavity is achieved, and the braiding angle of the close mesh braiding stent of the inner layer is smaller, so that more head braiding is achieved.

2. The endovascular prosthesis of claim 1, wherein the tubular vascular stent is of tapered design.

3. The endovascular prosthesis of claim 1, wherein the dense mesh braided stent is covered with a cover.