Implantable 3D Braided Endovascular Prosthesis for Repair of Disrupted Aorta

Abstract

The present invention relates to an implantable endovascular prosthesis (1) for use in the treatment of aortic dissection. **Solution**: The endovascular prosthesis comprises at least one self-expanding braided framework (2) extending along an axis capable of expanding radially from a radially compressed state in a delivery configuration to a radially expanded state. The self-expanding braided framework (2) is formed by wires (3) of the same diameter (D3), has no impermeable cover layer, and comprises a plurality of layers consisting only of wires (3) made of a biocompatible material. The braided framework forms part of the wall of the implantable endovascular prosthesis (1). The plurality of layers (3) consisting only of wires form lumens included in the self-expanding braided framework (2) and form a cylindrical shape with a circular cross-section. Each layer forms a mesh. The mesh forms a lattice by a plurality of wires of the layer. The meshes are interrelated. The wire (3) is incorporated into the mesh of at least one of the adjacent layers. Each wire (3) forms a helical path in one direction or the other around the axis of the self-expanding braided framework (2) and intersects the wire in the opposite helical direction and is located either outside or inside the self-expanding braided framework (2). The ratio (T2 / D3) of the wall thickness (T2) of the self-expanding braided framework (2) to the diameter (D3) of the wire (3) is at least 2.8. Among the wires in the same helical direction, the wire that most frequently occupies an outer position when intersecting the wire in the opposite helical direction in one turn of the helix is defined as the wire (OM wire) belonging to the outermost layer of the self-expanding braided framework. Among the wires in the same helical direction, the wire that most frequently occupies an inner position when intersecting the wire in the opposite helical direction in one turn of the helix is defined as the wire (IM wire) belonging to the innermost layer of the self-expanding braided framework. The number of OM wires is 5% or more and 35% or less of the total number of wires (3) forming the self-expanding braided framework (2), and the number of IM wires is 10% or more and 35% or less of the total number of wires (3) forming the self-expanding braided framework (2).

Description

Technical Field

[0001] The present invention relates to an implantable endovascular prosthesis for the treatment of aortic dissection.

Background Art

[0002] The aorta is the largest blood vessel in the body and is responsible for transporting oxygen-rich blood from the heart to the rest of the body. The aorta is shaped like a walking stick, with the first part going upward towards the head (ascending aorta), then curving in a C-shape (aortic arch), from which smaller arteries extend to carry blood to the head and arms. After the curve, the aorta becomes straight again and proceeds downward towards the abdomen, carrying blood to the lower part of the body (descending aorta). The wall of the aorta consists of three layers that provide structural support and ensure its shape.

[0003] Aortic dissection is one of the catastrophic conditions of the aorta with high mortality and morbidity. This typically occurs when the inner layer of the arterial wall becomes weak and a primary tear occurs into the middle layer of the wall. When this happens, blood can pass through the tear and has the potential to separate the layers from each other, i.e., to cause dissection. If no treatment is performed, the tear may expand. This results in the formation of a new channel called the false lumen (FL) by the intimal flap, separate from the true lumen (TL). This FL can gradually extend from the tear to the lowest part of the aorta and may prevent blood from flowing properly within the TL and perfusing the end organs connected to the aorta.

[0004] As shown in FIG. 1, the separation of the inner layer of the aorta that forms the intimal flap 104 may have multiple entry holes known as reentry tears 101. These secondary tears allow blood to flow between the TL 100 and the FL 102. As time passes, the FL compresses the true lumen, thus reducing blood flow towards the end organs and causing ischemia. In some cases, blood breaks through the outer layer of the aorta, causing a complication called aortic rupture, leading to life-threatening blood loss and a drop in blood pressure that requires immediate surgery. Aortic dissection occurring in the ascending aorta is called Stanford type A dissection, and aortic dissection in the descending aorta is Stanford type B dissection. Type B dissection is further classified into ultra-acute, acute, subacute, and chronic based on the degree of chronicity, where the ultra-acute phase corresponds to the first 24 hours from the onset of symptoms, the acute phase is the time between 24 hours and 14 days from the onset of symptoms, the subacute phase is between 2 weeks and 3 months, and the chronic phase corresponds to after 3 months.

[0005] Traditionally, type B aortic dissection (TBAD) without complications at the time of diagnosis is treated with optimal medical therapy and lifestyle modifications to minimize the risk of progression. However, up to 50% of patients may develop aortic-related complications such as expansion or rupture of the FL and retrograde dissection. If such complications are shown by imaging, repair should be considered.

[0006] Furthermore, there is accumulating evidence that dissections presenting as complications (defined as clinical signs of rupture or malperfusion) or high risk (defined as refractory pain, refractory hypertension, hemothorax, aortic diameter exceeding 40 mm, malperfusion on radiographs only, readmission, entry holes located in the lesser curvature of the aorta, or false lumen diameter exceeding 22 mm) should be treated by endovascular repair.

[0007] In fact, endovascular stent graft repair is known as an alternative option to traditional open surgical repair. Promotion of aortic repair with good FL regression and good TL dilation is expected. The limitations of stent grafts are related to their inherent properties and characteristics. First, due to the impermeability of the graft material, when a stent graft is placed in front of a lateral branch, such a branch is blocked, causing undesirable end-organ ischemia (e.g., spinal cord injury, renal insufficiency). Therefore, in order to suppress such side effects, short stent grafts are often used, but they have the drawback of not being able to cover the entire dissected aorta. As a result, retrograde FL perfusion due to backflow from secondary entry tears located distal to the stent graft continues, and / or the dissection spreads beyond the treatment area, potentially leading to a need for repeated therapeutic interventions.

[0008] Furthermore, cases of late distal new tears (SINE) and late extension of aortic dissection caused by stent grafts are often reported regarding the thoracic as well as abdominal and iliac segments. This can be caused by the high radial force and stiffness of the stent graft that partially covers the dissected part of the aorta, as well as the pulsatile movement that erodes the vulnerable intima at the distal edge of the stent graft.

[0009] To overcome these difficult challenges, the endovascular treatment strategy should not only aim to occlude the proximal access hole but also focus on preventing FL backflow by providing longer mechanical support to the dissected aorta to promote sufficient aortic repair.

[0010] Therefore, there is a need for an implantable endovascular device that has mechanical properties suitable for achieving good aortic repair, covers a long segment of the aorta with more entry points, can reduce the transmission of pressure and flow to the FL, while maintaining blood flow in the branches covered by this endovascular device at the thoracic and abdominal levels, and is not associated with a significant risk of complications such as spinal cord ischemia.

[0011] U.S. Patent Application Publication No. 2004 / 0073293 discloses a three-dimensional braided structure composed of a metal wire and a fiber strand. This structure is designed to create an impermeable device for the treatment of aneurysms. By utilizing the impermeable body, the device effectively blocks blood flow into the aneurysm sac, while also showing improved resistance to radial compression due to its three-dimensional braided stent. However, the impermeable body of the device does not address the problem of preventing occlusion of lateral branches.

[0012] U.S. Patent Application Publication No. 2004 / 0215332 discloses a multi-layer braided bare stent used for the treatment of aneurysms. It is stated that the multi-layer structure enhances resistance to crushing without reducing flexibility, but does not specify the braiding pattern required to exhibit these characteristics.

[0013] U.S. Patent No. 11,540,930 also discloses a multi-layer braided bare stent used for the treatment of aneurysms. The stent has a device thickness (T) exceeding three times the wire diameter (D). This type of stent can effectively form a thrombus in the aneurysm sac while maintaining blood flow in lateral branches. However, this patent does not mention any specific braiding pattern as a technical feature of the stent to obtain mechanical properties suitable for achieving good aortic repair in patients with aortic dissection. SUMMARY OF THE INVENTION

[0014] An object of the present invention is to provide a device that can be implanted by an endovascular approach for treating aortic dissection.

[0015] The subject matter of the present invention is defined in the appended independent claims. Preferred embodiments are defined in the dependent claims.

[0016] The subject of the present invention is an implantable intravascular prosthesis comprising at least one self-expanding braided framework extending along an axis that can expand radially from a radially compressed state to a radially expanded state in a delivery configuration. The braided framework is formed by wires of the same diameter D3 and does not have an impermeable cover layer. The braided framework comprises a plurality of layers consisting only of wires made of a biocompatible material and forms part of the wall of the implantable intravascular prosthesis. The plurality of layers consisting only of wires consists only of the lumens included in the braided framework. This forms a cylindrical shape with a circular cross-section. Each of the layers forms a mesh. These meshes form a lattice by a plurality of wires of the layer. The meshes are interrelated. The wires are incorporated into the mesh of at least one of the adjacent layers.

[0017] Each wire forms a helical path in one or the other direction around the axis of the self-expanding braided framework and intersects the wires in the opposite helical direction and is located either outside or inside the braided framework. The ratio T2 / D3 of the wall thickness T2 of the braided framework to the wire diameter D3 is at least 2.8, preferably at least 3.0, and most preferably at least 3.5. Among the wires in the same helical direction, the wire that most frequently occupies an outer position when intersecting the wires in the opposite helical direction in one turn of the helix is defined as the wire belonging to the outermost layer of the braided framework (OM wire). Among the wires in the same helical direction, the wire that most frequently occupies an inner position when intersecting the wires in the opposite helical direction in one turn of the helix is defined as the wire belonging to the innermost layer of the braided framework (IM wire). The number of OM wires is 5% or more and 35% or less of the total number of wires forming the braided framework, and the number of IM wires is 10% or more and 35% or less of the total number of wires forming the braided framework.

[0018] The pattern showing the arrangement of wires at the intersection is preferably repeated at least 4 times, more preferably at least 8 times, in one turn of the helix of the wire, in both helical directions.

[0019] The number of wires that form the braided framework but are neither OM wires nor IM wires is preferably 50% or more and 70% or less of the total number of wires forming the braided framework.

[0020] The ratio of the number of times the OM wires cross on the outside to the total number of crossings formed in one turn of the helix of the OM wires is preferably 70% or more and 90% or less.

[0021] The number of wires forming the braided framework is preferably at least 72, more preferably at least 96, even more preferably at least 120 and 200, and even more preferably 150 - 180.

[0022] The surface coverage rate (SCR) of the braided framework in the fully expanded state is preferably between 25% and 45%, more preferably between 30% and 40%.

[0023] The wires forming the braided framework preferably have a diameter D3 of 120μm or more and 250μm or less, more preferably 150μm or more and 220μm or less, and even more preferably 180μm or more and 210μm or less.

[0024] In a preferred embodiment, the cylindrical form of the braided framework preferably has a constant diameter in the fully expanded state. Preferably, the braided framework has an inner diameter of 20mm or more and 50mm or less in the fully expanded state.

[0025] In another preferred embodiment, the braided framework has one or both ends with a larger diameter in the fully expanded state. Preferably, the inner diameter of the braided framework is 20mm or more and 50mm or less in the fully expanded state.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0027] Detailed Description of the Invention As used hereinafter, the term "implantable" refers to the ability to place a medical device at a location within a body blood vessel by invasive means. An implantable medical device can be configured to be temporarily placed (e.g., for seconds, minutes, hours) within a body blood vessel during a medical intervention, or can be configured to remain permanently within a body blood vessel.

[0028] The term "intravascular" artifact refers to a device configured to be invasively placed within a curved or straight body vessel by a procedure that advances the artifact within the lumen of a body vessel, through the lumen of a body vessel, or from a remote location to a target site within a body vessel. In a vascular procedure, a medical device can be introduced "intravascularly" typically using a catheter on a guidewire under fluoroscopic guidance. The catheter and wire guide can be introduced through a conventional access site of the vascular system.

[0029] The term "catheter" refers to a tube inserted into a blood vessel for access to a target site. As used herein, "catheter" refers to either the catheter itself or a catheter including catheter accessories such as needles, guidewires, introducer sheaths, and other common and suitable medical devices known to those of skill in the art.

[0030] The term "permanent" refers to a medical device that may be placed intravascularly and remains intravascularly for an extended period of time (e.g., months, years), and in some cases, for the remainder of the patient's life.

[0031] The terms "expanded shape" or "expanded state" refer to a shape or state resulting from the self-expanding property of a self-spring-back object when it can expand in the absence of an external compressive force (i.e., a non-contracted state).

[0032] The implantable intravascular prosthesis 1 according to the present invention comprises at least one self-expanding braided framework 2. The self-expanding braided framework 2 assumes a compressed shape with a relatively small and relatively uniform diameter when placed within a delivery system (i.e., “in a compressed state”), and is configured to spontaneously assume a deployed shape with a radially expanded diameter at a delivery location such as a body lumen (i.e., “in a deployed state”). The self-expanding braided framework 2 has a 3D braided structure having a plurality of interconnected layers (interconnected multi-layer configuration) formed by braiding a plurality of wires. The self-expanding braided framework 2 comprises a lumen in the form of a tubular shape having a circular cross-section as shown in FIGS. 2, 2a, and 3.

[0033] In a preferred embodiment, the implantable intravascular prosthesis 1 may be substantially constituted by the self-expanding braided framework 2.

[0034] FIG. 4 shows a schematic cross-section of the implantable intravascular prosthesis 1 according to the present invention. FIG. 4a shows a schematic enlarged view of a part of the implantable intravascular prosthesis 1 consisting of the self-expanding framework 2.

[0035] The self-expanding braided framework 2 has a thickness T2 in a fully expanded state. This may be measured by using micro-CT scan technology or a digital optical comparator to identify the circumscribed circle and the inscribed circle of the cross-section of the braided framework 2 and dividing the difference in the diameters of these circles by 2. The term “interconnected multi-layer” refers to a framework, for example, having a plurality of layers, wherein the pri of those layers are not separate at the time of braiding, and a given number of wires of the pri of the first layer are intertwined with the pri of the second layer and / or other layers, as schematically shown in FIG. 5. This interconnected multi-layer configuration can be provided, for example, by using a braiding machine described in European Patent No. 1248872. When observing the self-expanding braided framework 2 perpendicular to its wall, the mesh of the self-expanding braided framework 2 forms a lattice by a plurality of levels of wires 3.

[0036] The ratio T2 / D3 of the wall thickness T2 of the self-expanding braided framework 2 to the diameter D3 of the wire 3 forming the braided framework 2 must be greater than 2.0. This is characterized in that the self-expanding braided framework 2 has two or more mesh layers, that is, a 3D braided structure having a multi-layer configuration. The ratio T2 / D3 is preferably at least 2.8, more preferably at least 3.0, and even more preferably at least 3.5. The larger the ratio T2 / D3, the greater the degree of multi-layering. The thickness T2 of the self-expanding braided framework 2 can vary depending on factors such as the braiding pattern, the diameter of the braided framework, and the properties of the wire. As a result, the thickness T2 is not systematically equal to the number of layers multiplied by the wire diameter (D3).

[0037] The term "OM wire" refers to the wire belonging to the outermost layer of the self-expanding braided framework 2, which can be defined as the wire that most frequently occupies the outer position when crossing the wire in the opposite helical direction in one turn of the helix among the wires in the same helical direction, when observing the crossing of the wire 3 perpendicular to the wall of the braided framework 3. "Most frequently" preferably means at least 70% of the total number of crossings in one turn of the helix. FIG. 5 shows the wire 31 in the same helical direction and the wire 32 in the helical direction opposite to the wire 31. The term "IM wire" means the wire belonging to the innermost layer of the self-expanding braided framework 2, which can be defined as the wire that most frequently occupies the inner position when crossing the wire in the opposite helical direction in one turn of the helix among the wires in the same helical direction. The position of the wire at the intersection can be specified by observing perpendicular to the wall of the self-expanding braided framework 2. That is, the term "outer position" means the wire that crosses above other wires when observing the intersection perpendicular to the wall, and the term "inner position" means the wire that crosses below other wires. In a preferred embodiment, the number of OM wires included in the self-expanding braided framework 2 is 5% or more and 35% or less of the total number of wires 3 forming the braided framework 2, and the number of IM wires is 10% or more and 35% or less of the total number of wires 3.

[0038] The number of times the "OM wire" is located outside at the intersection in its helical winding is preferably at most 90%, more preferably at least 80%. The number of times the "IM wire" is located outside at the intersection in its helical winding is preferably at least 5% and at most 20%, more preferably at least 10%. The pattern showing such an arrangement of wires at the intersection is preferably repeated at least 4 times, more preferably at least 8 times, in one turn of the wire helix in both helical directions. Wires that do not belong to either the outermost layer or the innermost layer can be defined as wires belonging to the intermediate layer. The number of wires belonging to the intermediate layer is preferably 50% or more and 70% or less of the total number of wires forming the braided framework. The more times the OM wire is located outside, the more flexible the implantable intravascular prosthesis becomes while maintaining the same radial force for the gradual repair of the dissected aorta.

[0039] The surface coverage ratio (SCR) of the self-expanding braided framework 2 of the intravascular prosthesis 1 is preferably 25% - 45% and more preferably 30% - 40% in the fully expanded state. The SCR of the endovascular prosthesis is defined by the following relationship. SCR = Sw / St

[0040] Here, "Sw" is the actual surface covered by the wires 3 constituting the braided framework 2, and "St" is the total surface of the wall of the braided framework 2 when observed perpendicular to the wall.

[0041] The self-expanding braided framework 2 of the intravascular prosthesis 1 is made of a maximum of 196 wires 3 and preferably made of 72 or more and 160 or less wires. The wire preferably has a diameter D3 of at least 120μm, preferably at least 150μm, more preferably at least 180μm, even more preferably at least 200μm, and at most 220μm.

[0042] The biocompatible material used in the present invention is preferably a stainless steel (e.g., 316, 316L, or 304); a nickel-titanium alloy including a shape memory type or a superelastic type (e.g., nitinol, nitinol-DFT (registered trademark)-platinum); a cobalt-chromium alloy (e.g., elgiloy); a cobalt-chromium-nickel alloy (e.g., finox); an alloy of cobalt, nickel, chromium, and molybdenum (e.g., MP35N or MP20N); a cobalt-chromium-vanadium alloy; a cobalt-chromium-tungsten alloy; a magnesium alloy; a titanium alloy (e.g., TiC, TiN); a tantalum alloy (e.g., TaC, TaN); L605, and is a metal substrate selected from the group consisting of. The metal substrate is preferably selected from the group consisting of nickel-titanium alloys such as titanium, nitinol and nitinol-DFT (registered trademark)-platinum, any type of stainless steel, or cobalt-chromium-nickel alloys such as finox (registered trademark).

[0043] One of the technical effects provided by the 3D braided structure of the self-expanding braided framework 2 is that the implantable endovascular artifact 1 spontaneously unfolds into the TL along the curve of the aorta without the need for balloon angioplasty, pushing the dissection flap and expanding the TL while reducing the FL. Therefore, the implantable endovascular artifact 1 has sufficient flexibility to follow the curvature of the aorta, as well as appropriate mechanical properties to push back the collapsed wall of the TL and gradually reposition it to the original pre-dissection diameter.

[0044] Furthermore, due to the permeability of the 3D braided structure of the self-expanding braided framework 2, the endovascular artifact 1 can keep the branches and side branches unobstructed without the need for additional repairs such as open debranching-bypass procedures, and does not require a customized fenestrated / branched configuration to maintain blood flow.

[0045] Example (3D braided configuration) Figure 6 shows a part of the self-expanding braided framework of Example 1 (Ex.1) according to the present invention. The braiding pattern of Ex.1 is shown in Table 1. The table shows which wire is arranged outside the self-expanding braided frame at each intersection within the repeating unit. For example, when the wire (C01) rotating in a clockwise helical manner is located outside at the intersection with the counterclockwise wire (A01), the letter "C" is written in the C01 - A01 cell. For example, to explain how to interpret the position of the wires at the intersection, the braiding pattern shown in Fig. 6a is replaced with Table 2. In this table, wires C-i, C-ii, and C-iii are taken as those braided in the clockwise direction (C wires), and wires A-i, A-ii, and A-iii are taken as those braided in the counterclockwise direction (A wires). Ex.1 was formed by 104 wires including 52 wires (C wires) braided clockwise and 52 wires (A wires) counterclockwise. In one turn (pitch) of the helix, the C wires crossed the A wires 52 times. Every 13 crossings, the pattern of wire positions was repeated. Therefore, the repeating unit consisted of 13 C wires and 13 A wires. This was repeated 4 times in one turn of the helix. In the repeating unit, 4 out of 13 C wires (C02, C05, C08, C11) and 2 out of 13 A wires (A03, A09) were identified as OM wires in the repeating unit (23.1%). Therefore, as summarized in Table 4, a total of 24 out of the 104 wires forming the braided framework were identified as OM wires because these wires were most frequently (11 out of 13 times) located outside within the pitch among the wires in the same helical direction. Both the clockwise-rotating and counterclockwise-rotating OM wires were located outside 11 out of 13 intersections (84.6%) within the repeating unit. As shown in Table 1, the IM wires for both rotations were located outside 2 out of 13 intersections (15.4%). These numbers counted in one turn (pitch) of the helix are summarized in Table 4. Table 5 summarizes how many times the repeating unit is seen in one turn of the helix.

[0046] Example 1 was braided using the multi-layer braiding machine described in European Patent No. 1248872. Of the 104 wires constituting the braided structure of Example 1, 32 wires were assigned to pass through one of the guide paths (referred to as the OM group) along the outermost periphery such as the guide paths 13a, 14a, 14b in FIG. 11. Another group of 32 wires was designated to pass through one of the guide paths (referred to as the IM group) along the innermost periphery such as the guide paths 10a, 10b, 11b in FIG. 11. The remaining wires were designated to pass through guide paths (such as the guide paths 11a, 12a, 12b, 13b in FIG. 11, referred to as the intermediate group) that do not cross either the outermost or the innermost periphery. It is important to note that FIG. 11 does not represent the configuration used and only shows how different wire paths are defined.

[0047] The thickness of the braided framework of Example 1 was measured using a digital optical comparator and was 0.72 mm. As a result, as shown in Table 6, by dividing the measured thickness T2 by the wire diameter D3 of 190 μm, the T2 / D3 ratio was calculated to be 3.79.

[0048] The braiding and technical characteristics of other examples (Ex.2 and Ex.3) of the self-expanding braided framework according to the present invention and comparative examples of the prior art (CEx.1 and CEx.2) manufactured according to the same procedure as Ex.1 (however, with different path configurations) are similarly summarized in Tables 3 to 5.

[0049] Thickness measurement and T2 / D3 ratio: The results of the thickness measurement and the calculated T2 / D3 ratio (derived from the measured thickness and wire diameter) are summarized in Table 6. All the braided frameworks including Ex.1 to Ex.3 and CEx.1 and CEx.2 evaluated in this test showed a T2 / D3 ratio exceeding 2.8.

[0050] Crushing resistance and elastic recovery: The purpose of the crushing resistance test is to evaluate the ability of the stent to resist permanent deformation over its entire length when exposed to a load uniformly applied over the entire length of the stent. This can quantify the energy required for the stent to return to its initial state and determine whether the stent recovers its original geometry after unloading (elastic recovery).

[0051] The crushing resistance of the self-expanding braided frameworks according to the present invention (Ex.1, Ex.2, and Ex.3), as well as comparative samples of the prior art (CEx.1 and CEx.2), was evaluated by a compression resistance parallel plate test performed using a tensile testing machine (Universal Mechanical Test System Lloyd from AMETEX, USA). These test samples were completely compressed by advancing the upper plate towards the lower plate between two flat plates. The crushing resistance was measured by recording the load and the associated displacement when compressing the sample until it was completely crushed and when releasing the sample to the initial position of the upper plate. The elastic recovery was calculated as the ratio (%) of the final diameter to the initial diameter.

[0052] The results of the crushing resistance test showed a clear difference in mechanical properties between the braided framework according to the present invention and the prior art, as shown in Table 7. Compared to the braided framework of the present invention, for one of the comparative samples of the prior art (CEx.1), the resistance to the crushing force increased significantly, while for the other comparative sample (CEx.2), there was no increase. The elastic recovery was found to be at least 96% for the braided framework according to the present invention. In contrast, the elastic recovery rates of the comparative samples of the prior art, namely CEx.1 and CEx.2, were 87.5% and 93.3% respectively, both of which were inferior to the elastic recovery rate of the braided framework according to the present invention. It has been demonstrated that the braided framework according to the present invention exhibits high elastic recovery characteristics and provides sufficient flexibility to follow the curve of the aorta after deployment. These frameworks are characterized by having a minimum of 5% and a maximum of 35% of the total number of wires as OM wires and a minimum of 10% and a maximum of 35% of the total number of wires as IM wires.

[0053] Self-expansion (conformability): The self-expansion of the braided framework was evaluated by visually observing the state of the braided framework after release from the completely collapsed state seen within the delivery catheter. The braided frameworks according to the present invention (Ex. 1 to Ex. 3) exhibited excellent self-expansion ability, returning to a preset diameter immediately after being released from the collapsed state within the delivery catheter and suffering no significant deformation (significant deformation is defined as an elastic recovery rate of less than 95%). In contrast, the prior art comparative samples (CEx. 1 and CEx. 2) showed deformations with an elastic recovery of less than 95% and were significantly insufficient in self-expansion as they could not be fully inserted into a delivery catheter of the desired diameter suitable for intravascular procedures (i.e., used in Ex. 1 to Ex. 3).

[0054] Based on the test results of elastic recovery and self-expansion ability, the braided frameworks having the braided pattern according to the present invention exhibit higher flexibility and conformability compared to the comparative samples. They enable good aortic repair while also providing coverage for long segments of the aorta.

[0055] Clinical results: A case of type B dissection with complications was treated by implanting the endovascular device according to the present invention from the ascending aorta to the abdominal aorta. Figures 7a - 7c show computerized tomography (CT) scans sliced at the plane of maximum compression of the TL observed preoperatively for this case. At the preoperative stage, the TL was collapsed by compression from the FL (Figures 7a and 8a). The celiac artery originated from both the true lumen and the false lumen. The left renal artery was supplied by the false lumen, while the remaining aortic branches originated from the true lumen (Figure 7a). In the implantation procedure, the endovascular device according to the present invention was deployed along the curve of the aortic arch from the ascending aorta to the abdominal aorta within the TL while covering the entry and re - entry tears of the FL, as well as the openings of major aortic branches such as the brachiocephalic artery, left common carotid artery, left subclavian artery, intercostal arteries, lumbar arteries, celiac artery, superior mesenteric artery, renal arteries, etc. In the postoperative evaluation, the TL increased due to the re - approximation of the intimal flap after deployment of the endovascular device, and at the same time, the diameter of the FL decreased (Figures 7b and 8b). In the 36 - month follow - up, the endovascular device provided support for the TL, gradually reducing the size of the FL while maintaining blood flow to the branches (Figures 7c and 8c). In conclusion, the implantable endovascular device according to the present invention demonstrated sufficient flexibility to follow the curve of the aorta, as well as sufficient mechanical properties to enable re - approximation and support of the intimal flap, re - expand the TL diameter, and restore blood flow to the TL. As a result, the endovascular device led to the successful repair of the dissected aorta while maintaining appropriate blood circulation to the aortic branches even when the openings of those branches were covered by the device.

[0056] Another case of type B aortic dissection (Figure 10a) was treated using the endovascular prosthesis according to the present invention. The endovascular prosthesis was implanted from the left common carotid artery (aortic arch) to the aortic-iliac artery bifurcation as shown in Figure 10b (at discharge) and Figure 10c (at 68-month follow-up). Computed tomography (CT) scans at the level of the celiac artery were used to evaluate the conditions before treatment, at discharge, and at 68-month follow-up (Figures 9a - 9c, respectively). Before the intervention, as seen in Figures 9a and 10a, the true lumen (TL) was compressed by the false lumen (FL). While the left renal artery originated from both the true and false lumens, the remaining aortic branches originated from the TL. The endovascular prosthesis according to the present invention was deployed within the TL from the aortic arch just distal to the left common carotid artery to the aortic-iliac artery bifurcation, covering the entire length of the dissection and the openings of the aortic branches including the left subclavian artery, intercostal arteries, lumbar arteries, celiac artery, superior mesenteric artery, right and left renal arteries, and inferior mesenteric artery (Figures 10b and 10c). Postoperative CT scan evaluation revealed an increase in the diameter of the TL due to the reopening of the TL and a decrease in the diameter of the FL (Figures 9b and 10b). At 68-month follow-up, the endovascular prosthesis provided support to the TL and gradually reduced the size of the FL while maintaining blood flow to the aortic branches (Figures 9c and 10c). In conclusion, the implanted endovascular prosthesis according to the present invention demonstrated appropriate flexibility to follow the natural curve of the aorta. Furthermore, it showed good mechanical properties that promoted the reopening and support of the TL. This led to the successful repair of the dissected aorta with a significant increase in the diameter of the TL and subsequent decrease in the diameter of the FL. Additionally, the endovascular prosthesis according to the present invention was proven effective in maintaining appropriate blood flow to the aortic branches even when covered by the endovascular prosthesis in the body.

[0057]

Table 1

[0058]

Table 2

[0059]

Table 3

[0060]

Table 4

[0061]

Table 5

[0062]

Table 6

[0063]

Table 7

Claims

1. An implantable intravascular prosthesis (1) for use in the treatment of aortic dissection, It comprises at least one self-expanding braided framework (2) that extends along the axis and is capable of expanding from a radially compressed state to a radially expanded state in the delivery configuration, wherein the self-expanding braided framework (2) has the same diameter (D ３ The wire (3) is formed by a plurality of layers consisting only of wire (3) made of a biocompatible material, and does not have an impermeable cover layer, forming part of the wall of the implantable intravascular prosthesis (1), the plurality of layers consisting only of wire (3) forming a lumen included in the self-expanding braided framework (2) which has a cylindrical shape having a circular cross-section, each layer forming a mesh, the mesh forming a grid of the plurality of wires of the layer, the mesh is interrelated, the wire (3) is incorporated into the mesh of at least one of the adjacent layers, each wire (3) intersects with wires in the opposite helical direction while forming a helical path in one direction or the other around the axis of the self-expanding braided framework (2), and is located either outside or inside the self-expanding braided framework (2), the diameter (D ３ ) the wall thickness (T ２ ) ratio (T ２ / D ３ ) is at least 2.8, An implantable intravascular prosthesis (1) is defined as follows: Among wires with the same helical direction, the wire that most frequently occupies the outermost position when intersecting with a wire with the opposite helical direction in one turn of the helix is ​​defined as a wire belonging to the outermost layer of the self-expanding braided framework (OM wire); among wires with the same helical direction, the wire that least frequently occupies the outermost position when intersecting with a wire with the opposite helical direction in one turn of the helix is ​​defined as a wire belonging to the innermost layer of the self-expanding braided framework (IM wire); and wires that are neither OM wires nor IM wires are defined as wires belonging to the intermediate layer of the self-expanding framework. An implantable intravascular prosthesis (1) characterized in that the number of OM wires is 5% to 35% of the total number of wires (3) forming the self-expanding braided framework (2), and the number of IM wires is 10% to 35% of the total number of wires (3) forming the self-expanding braided framework (2).

2. The implantable intravascular prosthesis (1) according to claim 1, wherein a pattern indicating the position of the wire at the intersection is repeated at least four times in one turn of the helix of the wire in both helical directions.

3. The implantable intravascular prosthesis (1) according to claim 1 or 2, wherein the number of wires that are neither OM wires nor IM wires is 50% or more and 70% or less of the total number of wires forming the self-expanding braided framework (2).

4. The implantable intravascular prosthesis (1) according to claim 1 or 2, wherein the ratio of the number of times the OM wire crosses on the outside to the total number of crosses formed in one turn of the OM wire spiral is 70% or more and 90% or less.

5. The implantable intravascular prosthesis (1) according to claim 3, wherein the ratio of the number of times the OM wire crosses on the outside to the total number of crosses formed in one turn of the OM wire spiral is 70% or more and 90% or less.

6. The implantable intravascular prosthesis (1) according to claim 1 or 2, wherein the number of wires forming the self-expanding braided framework is at least 72.

7. The implantable intravascular prosthesis (1) according to claim 3, wherein the number of wires forming the self-expanding braided framework is at least 72.

8. The implantable intravascular prosthesis (1) according to claim 4, wherein the number of wires forming the self-expanding braided framework is at least 72.

9. The implantable intravascular prosthesis (1) according to claim 5, wherein the number of wires forming the self-expanding braided framework is 150 to 180.

10. The implantable intravascular prosthesis (1) according to claim 1 or 2, wherein the surface coverage (SCR) of the self-expanding braided framework (2) in the fully expanded state is between 25% and 45%.

11. The implantable intravascular prosthesis (1) according to claim 3, wherein the surface coverage (SCR) of the self-expanding braided framework (2) in the fully expanded state is between 25% and 45%.

12. The implantable intravascular prosthesis (1) according to claim 4, wherein the surface coverage (SCR) of the self-expanding braided framework (2) in the fully expanded state is between 25% and 45%.

13. The implantable intravascular prosthesis (1) according to claim 5, wherein the surface coverage (SCR) of the self-expanding braided framework (2) in the fully expanded state is between 30% and 40%.

14. The wires (3) forming the self-expanding braided framework (2) have a diameter (D) of 120 μm or more and 250 μm or less. ３ An implantable intravascular prosthesis (1) according to claim 1 or 2, having the following characteristics:

15. The implantable intravascular prosthesis (1) according to claim 3, wherein the wire (3) forming the self-expanding braided framework (2) has a diameter (D3) of 120 μm or more and 250 μm or less.

16. The implantable intravascular prosthesis (1) according to claim 4, wherein the wire (3) forming the self-expanding braided framework (2) has a diameter (D3) of 120 μm or more and 250 μm or less.

17. The implantable intravascular prosthesis (1) according to claim 5, wherein the wire (3) forming the self-expanding braided framework (2) has a diameter (D3) of 180 μm or more and 210 μm or less.

18. The implantable intravascular prosthesis (1) according to claim 5, wherein the tubular shape of the self-expanding braided framework (2) has a constant diameter when fully expanded.

19. The self-expanding braided framework has an inner diameter of 20 mm to 50 mm in the fully expanded state, as described in claim 18 (1).

20. The implantable intravascular prosthesis (1) according to claim 5, wherein the self-expanding braided framework (2) has one or both ends with a larger diameter when fully expanded.

21. The implantable intravascular prosthesis (1) according to claim 20, wherein the inner diameter of the self-expanding braided framework (2) is 20 mm or more and 50 mm or less in the fully expanded state.

22. The implantable intravascular prosthesis (1) according to claim 5, wherein the ratio (T2 / D3) of the self-expanding braided framework is at least 3.

0.

23. The implantable intravascular prosthesis (1) according to claim 22, wherein the ratio (T2 / D3) of the self-expanding braided framework is at least 3.5.

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