Implantable intraluminal prosthesis

Abstract

To provide a device that can be implanted via an endovascular approach to treat aneurysms that include branches. The present invention provides an implantable intraluminal prosthesis having a multi-layer construction including at least one self-expanding braided framework; the self-expanding braided framework has a wire diameter (Φ 21 ), the self-expanding braided framework includes multiple layers of wires made of a biocompatible material; each layer forms a mesh; the meshes are intertwined, and the wires are embedded in the mesh of at least one of the adjacent layers; and the thickness of the wall of the implantable endoluminal prosthesis (T1) in a radially expanded state versus the diameter of the wires (21) (Φ 21 ) ratio (T1 / Φ 21 ) is greater than 3.0; and the surface coverage ratio (SCR) of said braided framework is at least 30% and at most 50%.

Description

[Technical field]

[0001] FIELD OF THEINVENTION The present invention relates to an implantable endoluminal prosthesis, more particularly to an endoluminal prosthesis for the treatment of aneurysms involving bifurcations. [Background technology]

[0002] 2. Background of the Invention Endovascular repair is known to be a relatively new minimally invasive technique for treating aortic aneurysms. It involves delivering an impermeable tube (graft) supported by a metal or plastic frame (stent) via a distantly located blood vessel. However, because it is impermeable, this technique cannot be applied to aneurysm repairs where the aneurysm involves significant branches (e.g., coronary arteries, superior aortic branches, renal and middle adrenal arteries, visceral arteries, and internal iliac arteries). Otherwise, it would cause severe complications with occlusion of the branches. Summary of the Invention [Problem to be solved by the invention]

[0003] Summary of the Invention SUMMARY OF THE PRESENT EMBODIMENT It is a first object of the present invention to provide a device that can be implanted via an endovascular approach to treat aneurysms involving bifurcations.

[0004] Another object of the present invention is to ensure branch patency during treatment of an aneurysm. [Means for solving the problem]

[0005] The subject matter of the invention is defined in the accompanying independent claims. Preferred embodiments are defined in the dependent claims.

[0006] The subject of the present invention is an implantable intraluminal prosthesis having a multi-layered configuration and including at least one self-expanding braided framework that is expandable from a radially compressed state in a delivery configuration to a radially expanded state and extends along an axis. 21 The braided framework is devoid of any impermeable covering layer and forms the wall of the endoluminal prosthesis. The braided framework comprises a cylindrical lumen of circular cross section and constant diameter. The wall thickness T of the endoluminal prosthesis in the radially expanded state 1 Wire pair diameter Φ 21 Ratio of T 1 / Φ 21 is greater than 2.0, preferably at least 2.5, more preferably at least 3.0, even more preferably at least 3.5, and even more preferably 4.0. The surface coverage ratio (SCR) of the endoluminal prosthesis in the radially expanded state is greater than 30% and less than 70%, preferably greater than 35% and less than 50%.

[0007] The self-expanding braided framework preferably comprises at least 90 wires and at most 130 wires; and the diameter of the wires is at least 120 μm, preferably at least 200 μm and at most 220 μm.

[0008] In another preferred embodiment, in a radially expanded state, the self-expanding framework comprises multiple layers of wires made of a biocompatible material; each layer forms a mesh; the meshes form a lattice with the wires of said layers; the meshes are intertwined, and the wires are embedded in the mesh of at least one of the adjacent layers.

[0009] BRIEF DESCRIPTION OF THE DRAWINGS Other particularities and advantages of the invention will now be described with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0010] [Figure 1-1a] FIG. 1 is a schematic front view of an endoluminal prosthesis according to the present invention, and FIG. 11a is a schematic enlarged view of a portion of the front view shown in FIG. [Diagram 2] FIG. 2 is a side view of the endoluminal prosthesis shown in FIG. 1. [Figure 3-3a] FIG. 3 is a cross-sectional view of the endoluminal prosthesis shown in FIGS. 1, 1a and 2 according to the cutting plane III-III, and FIG. 3a is a schematic enlarged view of an embodiment of a portion of the cross-sectional view shown in FIG. [Figure 3b] 4 is a schematic enlarged view of another embodiment of a portion of the cross-sectional view shown in FIG. 3. [Figure 4] 2 is a schematic enlarged view of another portion of an endoluminal prosthesis according to the present invention; FIG. [Diagram 5] 1 illustrates two stages of the healing process of an aneurysm in which an endoluminal prosthesis according to the present invention has been implanted. [Figure 6] 1 illustrates two stages of the healing process of an aneurysm in which an endoluminal prosthesis according to the present invention has been implanted. [Figure 7] 1 shows a simulation of blood flow velocity at an aortic branch ostium using a prior art stent and an endoluminal prosthesis according to the present invention. [Figure 8] 1 shows a simulation of blood flow velocity at an aortic branch ostium using a prior art stent and an endoluminal prosthesis according to the present invention. [Figure 9a-9b] 1 shows a simulation of blood flow velocity in an aortic model according to the prior art (without a stent) and with an endoluminal prosthesis according to the present invention. [Figure 10a-10b] FIG. 9b is a close-up view of the superior aortic branch ostium of the simulation shown in FIG. 9a. [Figure 11a-11b] FIG. 9b is a close-up view of the coronary ostium of the simulation shown in FIG. 9a. [Figure 12] FIG. 1 is a schematic cross-sectional view of the aorta illustrating a method for measuring the width and height of the aortic arch. [Figure 13]1 illustrates different phases of the healing process of a saccular aneurysm including a branch using an endoluminal prosthesis according to the present invention. [Figure 14] 1 illustrates different phases of the healing process of a fusiform aneurysm including a branch using an endoluminal prosthesis according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Detailed Description of the Invention In the following, the term "implantable" refers to the ability of a medical device to be positioned at a location within a body vessel. An implantable medical device may be configured to be placed within a body vessel temporarily (e.g., for seconds, minutes, hours) during a medical intervention, or to remain within the body vessel permanently.

[0012] The term "endoluminal" or "transluminal" prosthesis refers to a device adapted to be placed within a curved or straight body vessel by a procedure, where the prosthesis is advanced through the lumen of the body vessel from a remote location to a target site within the body vessel. In vascular procedures, medical devices may generally be introduced "intravascularly" using a catheter over a wire guide under fluoroscopic guidance. The catheter and wire guide may be introduced through a conventional insertion site in the vascular system.

[0013] The term "catheter" refers to a tube that is inserted into a blood vessel to access a target site. In this description, "catheter" refers to either the catheter itself or a catheter with its accessories, i.e., needles, guidewires, introducer sheaths, and other common and suitable medical devices known to those skilled in the art.

[0014] The term "permanent" refers to a medical device that can be placed within a blood vessel and that remains within the vessel for an extended period of time (eg, months, years), and possibly for the rest of the patient's life.

[0015] The endoluminal prosthesis 1 is configured to assume a compressed shape having a relatively small and relatively uniform diameter when placed in a delivery system (i.e., in a "compressed state"), and to spontaneously assume an expanded shape with a radially expanded diameter when placed in a delivery site, such as a body lumen (i.e., in an "expanded state"). As used herein, the term "expanded shape" or "expanded state" refers to a shape or state resulting from the self-expanding properties of a self-springback object (e.g., braided framework 20) ​​when it is allowed to expand in the absence of any external compressive force (i.e., in an unconstrained state). In addition to these definitions, the term "nominal diameter" refers to the diameter of an implantable endoluminal prosthesis when placed in a target blood vessel. Generally, the nominal diameter (Φ) of a self-expanding device designed to be permanently placed in a body lumen is defined as the diameter of the implantable endoluminal prosthesis. nor ) is the external compression force (Φ exp ) is 10 to 25% smaller than the outer diameter of the device when deployed.

[0016] The implantable endoluminal prosthesis 1 according to the present invention comprises at least one self-expanding braided framework 20 that can expand from a radially compressed state of a delivery configuration to a radially expanded state. The implantable endoluminal prosthesis 1 has a multi-layer configuration, either comprising at least two of the self-expanding braided frameworks 20 or comprising at least one self-expanding braided framework 20 having multiple intertwined layers (intertwined multi-layer configuration) formed by braiding multiple wires. The braided framework 20 comprises a cylindrical lumen of circular cross-section and constant diameter, as shown in Figures 1, 1a and 2.

[0017] When an endoluminal prosthesis 1 having a multi-layered configuration is observed perpendicular to the wall, the mesh of the braided framework 20 forms a lattice with multiple levels of wires 21. Figure 3 shows a schematic cross-sectional view of an endoluminal prosthesis 1 according to the invention. Figure 3a shows a schematic enlarged view of a portion of the endoluminal prosthesis 1 including a self-expanding framework 20, and Figure 3b shows a portion of the endoluminal prosthesis 1 including two self-expanding frameworks 20. The wall thickness T of the endoluminal prosthesis 1 is1 Diameter of paired wire 21 Φ 21 Ratio of T 1 / Φ 21 should be greater than 2.0, characterizing an endoluminal prosthesis 1 having more than a single layer of mesh, i.e., a multi-layer configuration. The braided framework 20 preferably has a thickness T 20 The term "intertwined multi-layer" refers to a framework that includes multiple layers, the plies of which are not differentiated at the time of braiding, e.g. a given number of wires of a ply of a first layer 22 are intertwined with plies of a second layer 23 and / or other layers, as shown, for example, diagrammatically in FIG. 4. Said intertwined multi-layers are, for example, described in EP Patent No. 1248 8 The braiding machine may be used as described in US Pat. No. 72.

[0018] The thicker wall T of the multi-layered endoluminal prosthesis 1 compared with the wall thickness of a conventional stent 1 Thanks to this, the endoluminal prosthesis 1 exhibits three-dimensional (3D) porosity. The thicker the wall (for a given wire diameter Φ 21 ), the effect of 3D porosity becomes greater.

[0019] One of the technical effects brought about by the 3D porosity of the endoluminal prosthesis 1 is that instead of mechanically / physically preventing blood flow from entering the aneurysm as is the case with conventional stent-graft techniques, the endoluminal prosthesis 1 converts the blood flow into the aneurysm sac from an undesired and damaging turbulent flow into the aneurysm sac into a smooth laminar flow 11 (as shown in FIG. 5) due to its multi-layered configuration. It eliminates the aneurysm by forming a protectively organized thrombus 12, known as Zhan's layer (see FIG. 6), while the branches and collateral branches remain unobstructed. Thanks to the permeable multi-layered structure of the endoluminal prosthesis 1, additional repairs, such as open debranching-bypass procedures and custom fenestrated / branched configurations to maintain blood flow, are not required.

[0020] The surface coverage (SCR) of the endoluminal prosthesis 1 in its radially expanded state is between 30% and 70%, preferably greater than 35% and less than 50%, even more preferably less than 45%. The SCR of the endoluminal prosthesis is determined by the formula: SCR=S w / S t where "S w " is the actual surface covered by the wire 21 configured in the endoluminal prosthesis 1, and "S t " is the total surface area of ​​the wall of the endoluminal prosthesis 1 when viewed perpendicular to the wall.

[0021] Research and experiments carried out by the inventors have led to unexpected and surprising results. Irrigation at the branches, instead of occluding these branches, has an SCR of the endoluminal prosthesis of 30% to 70%, with a ratio T 1 / Φ 21 The larger the endoluminal prosthesis 1 is placed in front of the ostium 34, the chaotic flow is eliminated and transformed into a regulated laminar flow by passing through the wall of the endoluminal prosthesis. This accelerates the flow in the branch covered by the endoluminal prosthesis 1. Thus, in the radially expanded state, the ratio T of the endoluminal prosthesis 1 is increased by 100%. 1 / Φ 21 should be greater than 2.0, preferably at least 2.5, more preferably at least 3.0, even more preferably at least 3.5, and even more preferably 4.0, while the SCR is between 30% and 70%, preferably between 35% and 50%. 1 / Φ 21Comparable simulations of blood flow in an aortic model without and with an endoluminal prosthesis with a β value of more than 2.0 are shown in Fig. 9a and Fig. 9b, respectively. The aortic model was created based on the actual pathology of the patient. In Fig. 9b, the endoluminal prosthesis is placed to cover the wall of the vessel from the coronary artery 31 to the superior aortic branch 30. Such treatment surprisingly increases the velocity of blood flow entering the superior aortic branch 30 at its ostium 34 by 21% to 24%, as shown in Fig. 10b (enlarged view of Fig. 9b), in particular, when compared to the velocity without the device as shown in Fig. 10a (enlarged view of Fig. 9a). The flow velocity in the coronary artery also increases by up to 20%, as shown in Figs. 11a and 11b.

[0022] A further characteristic improvement of the "perfusion" in the branches covered by the endoluminal prosthesis 1 was observed with this intertwined multi-layer configuration. The braided framework 20 of the endoluminal prosthesis 1 is made of at most 196 wires 21, preferably at least 90 wires and at most 130 wires. The wire diameter (Φ 21 ) is preferably at least 120 μm, preferably at least 150 μm, more preferably at least 180 μm, even more preferably at least 200 μm, and at most 220 μm.

[0023] Another advantage of the present invention is that the higher values ​​of the ratio T 1 / Φ 21 The implantable endoluminal prosthesis 1 has a lower T 1 / Φ 21 The wall thickness T of the endoluminal prosthesis 1 of greater than 2.0 can effectively form a thrombus in the aneurysm sac compared to a braided framework having a 1 Wire diameter Φ of pair wire 21 21 Ratio of T 1 / Φ 21 characterizes an endoluminal prosthesis 1 having more than a single layer of mesh. 1 / Φ 21The larger the wires, the more layers the endoluminal prosthesis 1 includes. Each of the wires forming the multiple layers acts to provide laminar blood flow through the wall of the endoluminal prosthesis 1.

[0024] The curvature of the aortic arch 32 is generally defined as the width of curvature W as described in Ou et al. J. Thorac. Cardiovasc. Surg. 2006;132:1105-1111. 32 and height H 32 It is specified by measuring the width W 32 is measured as the maximum horizontal distance between the midpoint 35 of the ascending aorta and the midpoint 35 of the descending aorta 32, close to the axial plane through the right pulmonary artery; and the height of the aortic arch H 32 As shown in Figure 12, 32 and aortic arch W 32 35 is measured as the maximum vertical distance between the midpoint of the maximum height of

[0025] Ratio T of at least 2.5 1 / Φ 21 The intertwined multi-layered configuration provides important advantageous technical properties. When the aneurysm is on the outside of the curve, it is paramount to set an optimal SCR and optimal opening diameter of the mesh on the outside of the curve to form a protective organized thrombus of the aneurysm sac by converting the undesired damaging turbulent flow 33 into smooth laminar flow 36 while preserving the patency of the branches, e.g., the superior aortic branch 30. The intertwined multi-layered wires of the present invention have a large gap between adjacent parallel wires. Certain The distance shift allows the SCR to remain nearly the same in curved and straight configurations. 1 / Φ 21 When a conventional single-layer mesh-like tube with a ratio T of less than 2.0 is deployed in a curved lumen, the SCR outside the curve is much lower than the SCR in a straight configuration. 1 / Φ 21should be greater than 2.0, preferably at least 2.5, more preferably at least 3.0, even more preferably at least 3.5, and even more preferably at least 4.0.

[0026] Contrary to the "normal" expectation that the space between the aneurysm wall and the endoluminal prosthesis would be occluded by a thrombus as shown in Figure 6, another surprising effect provided by the present endoluminal prosthesis 1 with its intertwined multi-layer configuration is that the aneurysm including the branch directly shrinks instead of forming a thrombus in the aneurysm sac while still maintaining blood flow into the branch as shown in Figures 13 and 14. The inventors hypothesize that by sealing the beginning of the aorta, the expanded undesirable turbulent flow 33 is eliminated and the desired smooth flow 11 is created in this volume. This accelerates the non-turbulent blood flow entering the branch while reducing the pressure under the Venturi effect, resulting in the shrinkage of the aneurysm sac.

[0027] The biocompatible material used in the present invention is preferably a metal substrate selected from the group consisting of stainless steel (e.g. 316, 316L or 304); nickel-titanium alloys, including shape memory or superelastic types (e.g. Nitinol, Nitinol-DFT®-Platinum); cobalt-chromium alloys (e.g. Elgiloy); cobalt-chromium-nickel alloys (e.g. Phynox); alloys of cobalt, nickel, chromium and molybdenum (e.g. MP35N or MP20N); cobalt-chromium-vanadium alloys; cobalt-chromium-tungsten alloys; magnesium alloys; titanium alloys (e.g. TiC, TiN); tantalum alloys (e.g. TaC, TaN); L605. The metal substrate is preferably selected from the group consisting of titanium, nickel-titanium alloys, such as Nitinol and Nitinol-DFT®-Platinum, any type of stainless steel, or cobalt-chromium-nickel alloys, such as Phynox®.

Claims

1. An implantable intraluminal prosthesis (1) for use in treating an aneurysm occurring in a branched artery, the prosthesis having a multi-layer construction consisting essentially of at least one axially extending self-expanding braided framework (20) expandable from a radially compressed state in a delivery configuration to a radially expanded state; the self-expanding braided framework (20) is a single, given wire diameter (Φ ２１ ), said self-expanding braided framework (20) is devoid of any impermeable covering layer and comprises a plurality of layers of wires (21) made of a biocompatible material; and forms the wall of said endoluminal prosthesis (1); each layer forms a mesh; said mesh forms a lattice with the plurality of wires (21) of said layer; said mesh is intertwined, said layers being indistinguishable upon braiding, wires of a first layer being intertwined with wires of a second and / or other layer, each wire being embedded in the mesh of at least one of the adjacent layers; said self-expanding braided framework (20) is in an implantable endoluminal prosthesis (1) comprising a cylindrical lumen of circular cross section and constant diameter; in a radially expanded state, the wall thickness (T １ ) to the diameter (Φ ２１ ) ratio (T １ / Φ ２１ ) is 2.5 to 3.0; and the surface coverage ratio (SCR) of the braided framework (20) is at least 35% and at most 50%, the diameter of the wires (21) is at most 220 μm, the multi-layered wires shift to maintain a constant distance between adjacent parallel wires, and the SCR is maintained in curved and straight configurations.

2. 2. The implantable endoluminal prosthesis (1) according to claim 1, wherein the self-expanding braided framework (20) comprises at least 90 wires and at most 130 wires.

3. 3. The implantable endoluminal prosthesis of claim 1 or 2, wherein the biocompatible material is a metallic substrate selected from the group consisting of titanium, nickel-titanium alloys, any type of stainless steel, and cobalt-chromium-nickel alloys.

4. The implantable intraluminal prosthesis of any one of claims 1 to 3, wherein the biocompatible material is a metal substrate selected from the group consisting of Nitinol, Nitinol-DFT (registered trademark)-Platinum, and Phynox (registered trademark).

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