Stent graft prosthesis

Abstract

A stent graft prosthesis for repairing a defective natural blood vessel includes a tubular fabric member having at least a first end and a second end. At least one of the ends is supported by a combination of two cooperating ring stents of different configurations. The tubular fabric member is attached to each of the ring stents at selected points. At least one of the ring stents is compressible into a folded "saddle" shape with two peaks and two valleys. The other ring stent intersects the "saddle"-shaped ring stent at four points, each point being in the region between the peaks and valleys of the folded "saddle" shape. When deployed, the other ring stent can be selected from a circular or cylindrical shape, a saddle-shaped ring stent, a ring stent with one or more V-shaped hinged sections with curved sections between them, or a "Z"-shaped stent.

Description

Technical Field

[0001] The present disclosure relates to a prosthesis device that can be placed at a target treatment site within the lumen of a natural blood vessel for the purpose of supplementing the natural function of the natural blood vessel when its ability to perform its natural function declines due to a patient's illness, injury, or natural aging process. In particular, an improvement in a method for fixing a prosthesis device to a target treatment site is disclosed.

Background Art

[0002] Artificial prostheses consisting of tubular conduits with open lumens are well known and have been used in surgical procedures and hybrid surgical procedures. Currently, in appropriate cases, it is preferred to use a minimally invasive delivery system to place a prosthesis at a treatment site in the body to replace a diseased or damaged natural body cavity, such as a blood vessel or other hollow organ such as a bile duct or a portion of the intestine. The most common use of such endoprostheses is to replace a diseased or damaged blood vessel.

[0003] Some vascular disorders can be treated by using an artificial prosthesis. A dissection in which the inner layer of a natural blood vessel such as the aorta tears or separates is also one of such disorders. For example, in aortic dissection, the intima peels off from the media, and rapid blood inflow through the tear causes the dissection to progress, the blood vessel to expand unnaturally, and / or blood leakage (hemorrhage). Blood may flow between the layers of the blood vessel, resulting in the aorta rupturing or the blood flow being diverted, causing insufficient blood flow to the organs (ischemia).

[0004] Another relatively common vascular disorder is an aneurysm. An aneurysm typically occurs when a portion of the natural blood vessel wall of the aorta dilates and bulges outward. Small aneurysms rarely, if ever, cause symptoms, but large aneurysms pose a significant risk to patients. Rupture of a large aneurysm can occur without warning and is usually fatal, so early diagnosis and treatment are highly important. With the increasing aging population, the incidence of aneurysms continues to rise in Western societies.

[0005] If an aneurysm is diagnosed before it ruptures, surgical treatment to repair the affected blood vessel wall is effective. In the surgical treatment of aneurysms, under general anesthesia that allows access to the patient's abdomen or thorax, the aneurysm site of the aorta is replaced or reinforced with a synthetic graft or prosthesis (see Non-Patent Document 1). The patient then has a normal average life expectancy.

[0006] Currently, for the repair of aneurysms or dissections, many methods are adopted that involve delivering a graft made of fabric or ePTFE by catheter and deploying a metallic stent element to hold it in place. Since the graft / stent can be delivered by catheter, the surgical intervention only requires a small incision to expose the femoral artery. Under appropriate circumstances, the device can be deployed percutaneously. Delivery by catheter allows the use of local anesthetics because the procedure is less invasive. Therefore, catheter delivery leads to a reduction in mortality and morbidity and a shortening of the recovery time, which is beneficial. For example, endovascular repair is typically used for the treatment of infrarenal abdominal aortic aneurysms where a graft is placed below the renal arteries. Currently, many different types of devices useful for endovascular repair are available. For example, there are elastically engaging endovascular elements described in Patent Document 1 (Vascutek), or tubular fabric liners having a radially expandable support frame and radiopaque marker elements sutured to the liner described in Patent Document 2 (Medtronic).

[0007] Endovascular techniques involve the delivery of prostheses by catheter. The inner lumen of the catheter defines the maximum dimension of the prosthesis to be inserted. Therefore, much effort has been expended in designing prostheses that can be packaged in a minimal volume and easily deployed once placed in the desired location.

[0008] One successful type of prosthesis is the "stent graft" that includes a conduit formed from a flexible sleeve attached to a rigid support or stent. The sleeve is typically made of a physiologically acceptable fabric (usually a knitted or woven fabric) of expanded polytetrafluoroethylene (ePTFE), PTFE, or polyester, polyethylene, or polypropylene, and optionally can be coated to reduce friction, prevent clotting, or deliver pharmaceuticals. Coatings of the fabric or its constituent fibers include antibacterial agents such as heparin, gelatin, collagen, or rifampicin. The fabric can be porous on at least one surface to allow for in-growth of cells. These materials are suitable for the currently disclosed stent graft prostheses. The stent can be made balloon-expandable (e.g., a PALMAZ stent made of rigid stainless steel wire). However, the stent can also be self-expanding and formed of a shape memory material such as nitinol (nickel-titanium alloy). A number of different stent designs are known in the art. For example, there are the braided stents described in Patent Document 3, or the wire "zigzag" stents described in Patent Document 4. Typically, the stent design is adapted to the requirements of compact packaging for delivery by radial or axial deformation, or a combination thereof, and to a slim configuration temporarily held using a removable sleeve or release wire.

[0009] Another useful design is a "saddle" shaped ring stent that can be formed from a wire into individual circular ring stents. This is normally flat (not distorted from the natural ring), but has sufficient elasticity to distort (fold) such that a first pair of diametrically opposed points on the circumference of the ring stent are displaced in a uniaxial direction. While a second pair of diametrically opposed points located centrally on the circumference between the first pair are displaced in the opposite axial direction, forming a symmetrical "saddle" shaped configuration. For convenience, the first pair of points can be described as "peaks" and the second pair of points as "valleys", or vice versa. The peaks and valleys are typically fixed to the tubular sleeve component of the graft prosthesis. The degree of axial displacement between the first pair of points and the second pair of points (this axial displacement is also referred to as the "saddle height") is a function of the original circumference of the ring stent before distortion (folding) to the final circumference of a circle that can accommodate the distorted (folded saddle shaped) configuration inside. Thus, the ratio of the final circumference to the original circumference can be used to simply represent the axial displacement. Generally, the final circumference is the outer circumference of the graft sleeve to which the stent is attached. The ratio of the oversize of the non-distorted inner circumference of the circular stent to the outer circumference of the graft sleeve also serves as a convenient measure of the "saddle" shape employed and can be calculated as follows.

Number

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Non-Patent Documents

[0011]

Non-Patent Document 1

Summary of the Invention

[0012] A stent graft prosthesis for repairing a defective natural blood vessel includes a tubular fabric member having at least a first end portion and a second end portion. At least one of those end portions is supported by a combination of two cooperating ring stents of different configurations. The tubular fabric member is attached at selected points to each of the ring stents. At least one of the ring stents is compressible into a folded "saddle" shape having two peaks and two valleys. The other ring stent intersects the "saddle" shaped ring stent at four points. Each point is in a region between the peaks and valleys of the folded "saddle" shape. The other ring stent, when deployed, can be selected from a circular or cylindrical shape, or a saddle shape, or a ring stent having one or more V-shaped hinge portions with curved portions therebetween, or a "Z" shaped stent.

[0013] In particular, the disclosed stent graft prosthesis has at least a first end portion and a second end portion and a length L extending between the first end portion and the second end portion f and an open lumen diameter D f and includes a tubular fabric member having the same. At least one of the first end and the second end of the tubular fabric member is supported by a combination of two cooperating ring stents of different configurations. Each of the two cooperating ring stents of different configurations is compressible into a folded shape to provide a compact delivery shape of the stent graft prosthesis. The tubular fabric member is attached to each of the two cooperating ring stents of different configurations at selected points. At least one of the two cooperating ring stents of different configurations is compressible into a folded "saddle" shape having two peaks and two valleys. The other of the two cooperating ring stents of different configurations intersects on at least one of the two cooperating ring stents of different configurations at four points. Each point is in a region between the peaks and valleys of the folded "saddle" shape.

[0014] The stent graft prosthesis is also such that the other of the two cooperating ring stents of different configurations is compressible into a folded "saddle" shape having two peaks and two valleys, and the peaks can be configured to be axially aligned with the peaks of at least one of the two cooperating ring stents of different configurations.

[0015] The stent graft prosthesis is also such that the other of the two cooperating ring stents of different configurations that is compressible into a folded shape is a shaped ring stent having at least one "V"-shaped hinge portion, and the "V"-shaped hinge portion can be configured to be axially aligned with the peak of at least one of the two cooperating ring stents of different configurations.

[0016] Disclosed herein is a stent graft prosthesis including the following. At least a first end and a second end, and a length L extending between the first end and the second end f And a tubular fabric member having the length L f Is the longest dimension of the continuous tubular fabric member aligned with the longitudinal axis of the tubular fabric member. The tubular fabric member has an open lumen diameter D fIt has. At least one of the first end and the second end of the tubular fabric member is supported by a combination of two cooperating ring stents of different configurations. Each of the two cooperating ring stents of different configurations is compressible into a folded shape for the purpose of compactly packaging the stent graft prosthesis for delivery into the lumen of a blood vessel. The tubular fabric member can optionally be made the same as or different from either of the two cooperating ring stents of different configurations, or can be supported over its entire length by one or more additional stents that can be the same or different. In particular, any of the additional stents or combinations thereof that can be disposed at or spaced from an intermediate position between the first end and the second end do not contact any of the two cooperating ring stents of different configurations when the stent graft prosthesis is fully deployed and the lumen of the tubular fabric member is open. Alternatively stated, for the purpose of use within a native blood vessel, the combination of two cooperating ring stents of different configurations disposed at the first end or the second end of the tubular fabric member, or at each end, does not engage with any other additional stents used to support the tubular graft member within its length and functions independently of such other additional stents (if any). The combination of two cooperating ring stents of different configurations disposed at either or both ends of the tubular fabric member functions to maintain a desired open circular configuration when the stent graft prosthesis is deployed in an operating configuration within the lumen of the blood vessel, acting to counteract the tendency for the open end to distort, become elliptical, or become flat, as can be observed when using a single steep-gradient saddle-shaped ring stent. The term "steep gradient" applies to a ring stent having "peaks" and "valleys" that have a significant axial distance between, for example, a range of peaks extending in one axial direction and a range of valleys extending in the opposite axial direction when folded into a saddle shape.

[0017] The term "combination of two cooperating ring stents of different configurations" relates to the functional relationship of two individual ring stents. Each of the two ring stents is different from the other with respect to its physical configuration, its folded and deployed shapes, and optionally the specific manner of its attachment to a portion of the tubular graft member. As a result, the two ring stents interact to improve the positioning and radial stability of the stent graft prosthesis while not being coupled together. Thus, portions of each ring stent can overlap or slide across intersecting portions during folding and deployment of the stent graft prosthesis. The interaction relationship of a combination of two cooperating ring stents of different configurations can be facilitated by selectively attaching each of the cooperating ring stents to an end of the tubular graft member of the stent graft prosthesis.

[0018] A combination of two cooperating ring stents of different configurations can comprise a foldable ring stent that has a circular or cylindrical shape when deployed, a foldable ring stent that has a saddle shape when deployed, and a foldable ring stent having one or more V-shaped hinge portions having a curved portion therebetween, selected from the group consisting of foldable ring stents. However, in the aforementioned combination of two cooperating ring stents of different configurations, only one foldable ring stent can be circular or cylindrical. As one of the two cooperating ring stents of different configurations, in the case of a foldable ring stent having a plurality of "V"-shaped hinge portions connected together, that type of ring stent can be referred to as a "Z"-shaped stent. The foldable ring stent that has a saddle shape when deployed can be individually selected from ring stents selected from those whose deployed shape forms a saddle shape with a steep gradient to those that form a saddle shape without a steep gradient. As used herein, the term "steep gradient" is useful for comparing the ring stents used in a combination of two cooperating ring stents of different configurations. One of the folded ring stents can be considered, for example, with respect to the other ring stent that is folded and constrained for delivery, or in a combination of two cooperating ring stents of different configurations when in the deployed state, to distinguish one ring stent from the other.

[0019] A combination of two cooperating ring stents of different configurations includes a ring stent in which one of the two cooperating ring stents of different configurations intersects the other of the two cooperating ring stents of different configurations. Thus, one of the two cooperating ring stents of different configurations can be considered to be inside the other. Or, one is an outer ring stent and the other is an inner ring stent. Generally, the outer ring performs a sealing function to hold the fabric of the tubular fabric member against the surface of a healthy portion of a natural blood vessel, for example, so that the end of the stent graft prosthesis is properly sealed in its desired position. Further, generally, the inner ring serves to ensure shape retention, particularly radial stability, for the shape of the end of the tubular fabric member of the stent graft prosthesis, for example, to resist overexpansion of the open lumen, such as flattening, ovalization, fluting, elongation, or to suppress any tendency for the lumen at the deployed end of the stent graft prosthesis to distort from its designed configuration in one lumen cross-sectional dimension or another lumen cross-sectional dimension.

[0020] The following exemplary but not exhaustive list shows embodiments of combinations of two cooperating ring stents of different configurations that are useful for positioning and stabilizing at least one end of a stent graft prosthesis. An outer non-tapered saddle-shaped ring stent and an inner tapered saddle-shaped ring stent. An outer circular or cylindrical ring stent and an inner tapered saddle-shaped ring stent. An inner non-tapered saddle-shaped ring stent and an outer tapered saddle-shaped ring stent. An inner circular or cylindrical ring stent and an outer tapered saddle-shaped ring stent. An internally shaped ring stent having at least one flexible hinge portion in a "V" shape, the curved portion being on both sides of at least one shaped "V" shaped portion or between more than one flexible hinge portion in a "V" shape, and an external non-steep saddle-shaped ring stent. An internally shaped ring stent having at least one flexible hinge portion in a "V" shape, the curved portion being on both sides of at least one shaped "V" shaped portion or between more than one flexible hinge portion in a "V" shape, and an external circular or cylindrical ring stent. An external steep saddle-shaped ring stent and an internally radially compressible Z stent. An external circular or non-steep saddle-shaped ring stent and an internally radially compressible Z stent.

[0021] Disclosed herein is a stent graft prosthesis comprising the following. At least a first end portion and a second end portion, and a length L extending between the first end portion and the second end portion f and an open lumen diameter D f and having a tubular fabric member. At least one of the first end portion and the second end portion of the tubular fabric member is supported by a combination of two cooperating ring stents of different configurations, each of the two cooperating ring stents of different configurations being compressible into a folded shape for delivering the stent graft prosthesis to a treatment site. The tubular fabric member is attached to each of the two cooperating ring stents of different configurations at selected points. One of the two cooperating ring stents of different configurations intersects the other of the two cooperating ring stents of different configurations. The different configurations of the two cooperating ring stents include a configuration in which one of the two cooperating ring stents of different configurations is constrained from overexpansion by the other of the two cooperating ring stents of different configurations.

[0022] The different configurations of two cooperating ring stents can include a configuration in which one of the two cooperating ring stents of different configurations is a ring of relatively steep "saddle" shape and is constrained from overexpansion by the other of the two cooperating ring stents of different configurations.

[0023] The different configurations of two cooperating ring stents can include a configuration in which one of the two cooperating ring stents of different configurations is a ring with a relatively steep profile and constrains a shallower (unprofiled) ring stent from overexpansion. The latter is the other of the two cooperating ring stents of different configurations.

[0024] In an embodiment, in a combination of two cooperating ring stents of different configurations, one of the two cooperating ring stents of different configurations can include a ring stent as follows. That is, when the stent graft prosthesis is fully deployed and the lumen of the tubular fabric member is open, it is substantially circular or less steep than the other of the two cooperating ring stents of different configurations and is a ring stent disposed externally relative to the other of the two cooperating ring stents of different configurations. The other of the two cooperating ring stents can be of a relatively steep saddle shape. In such an embodiment, the circular or less steep ring stent, when deployed, functions as a main sealing ring for the end of the stent graft prosthesis.

[0025] In an embodiment, one or more ring stents can be deployed with the aid of an expandable balloon.

[0026] In a combination of two cooperating ring stents of different configurations, the ring stents may be formed from a shape memory material, folded compactly, and capable of returning to the desired shape for their use, for example facilitating folding into a compact package for delivery, such as within a constraining delivery sheath. For example, when deployed by removing the constraining delivery sheath, each ring stent of the combination of two cooperating ring stents of different configurations will open and tend to adopt the desired configuration within the constraint of the attached tubular fabric member and also within any additional constraint imposed by the natural blood vessel in which the stent graft prosthesis is deployed.

[0027] The desired configuration of the compressible ring stent in the deployed stent graft prosthesis can be ensured, for example, by pre-attaching the ring stent to the tubular fabric member at selected discrete points by suturing before the stent graft prosthesis is packaged within the constraining delivery sheath and after the constraining delivery sheath has been removed.

[0028] At least one ring stent in a combination of two cooperating ring stents of different configurations can be made radially expandable from a compact configuration to a circular or partially cylindrical configuration. At least one ring stent in a combination of two cooperating ring stents of different configurations that can be made radially expandable can have one or more V-shaped hinge portions and curved portions therebetween. Alternatively, at least one ring stent in a combination of two cooperating ring stents of different configurations that can be made radially expandable can have a plurality of V-shaped hinge portions connected together to provide a "Z"-shaped stent.

[0029] In a combination of two cooperating ring stents, at least one of the ring stents can be a "saddle-shaped" ring stent. The portion of this ring stent moves in both the axial and radial directions when folded into a compact configuration or deployed into an expanded configuration.

[0030] In a combination of two cooperating ring stents of different configurations, a radially expandable ring stent can be disposed within a "saddle-shaped" ring stent and attached to a tubular fabric member at selected points. This configuration encourages the "saddle-shaped" ring stent to maintain a generally circular cross-section axially within the tubular fabric member, suppressing "flaring" or "ovalization" from the desired open circular configuration and deformations so-called in this field, as observed in an unsupported "saddle-shaped" ring stent and resulting from the flattening of the open end of the tubular fabric member.

[0031] In an embodiment of a stent graft prosthesis, a shaped ring stent having at least one "V"-shaped hinge portion is at least partially disposed within the other of two cooperating ring stents of different configurations. This other of the two cooperating ring stents of different configurations is compressible into a "saddle" shape having peaks and valleys. The shaped ring stent is attached to the fabric of the tubular fabric member at the peaks of the "saddle-shaped" ring stent by the "V"-shaped hinge portion or by each "V"-shaped hinge portion of the shaped ring stent.

[0032] In an embodiment of a stent graft prosthesis, the tubular fabric member has a substantially circular perimeter at each of a first end and a second end. A ring stent compressible into a "saddle" shape is attached to the fabric of the tubular fabric member at a plurality of points around one of the first end and the second end. A cooperating shaped ring stent is selectively attached to a portion of the fabric of the tubular fabric member at the same end, and a ring stent compressible into a "saddle" shape having a peak portion and a valley portion is, for example, folded to compress the stent graft prosthesis for delivery into the lumen of a natural blood vessel, or during deployment of the stent graft prosthesis within the lumen of a natural blood vessel, as needed, allowed to slide over the shaped ring stent.

[0033] Combinations of two cooperating ring stents of different configurations have been found to provide end sealing and radial stability that are effective for a movement resistance function for a tubular graft prosthesis important for long-term implantation.

[0034] The use of a shaped foldable ring stent having one or more V-shaped hinge portions and curved portions therebetween, in combination with an outer ring stent compressible into a folded "saddle" shape having two peak portions and two valley portions, provides a combined end sealing stent for the tubular fabric member of a stent graft prosthesis disposed as a repair within a natural blood vessel. The "saddle" shaped end ring stent having two peak portions and two valley portions is configured as the outer ring stent thereabove and slidably intersects a portion of the shaped foldable ring stent, such that upon deployment of the stent graft prosthesis, the shaped ring stent expands radially and perpendicular to the natural blood vessel wall being repaired. This radial expansion encourages the "saddle" shaped ring stent into the desired circular cross-sectional shape while preventing the outer "saddle" shaped end ring stent from being distorted into a so-called "petal" shape or "ovalization" deformation.

[0035] Alternatively, each of the two cooperating ring stents of different configurations can be of the "saddle shape" type and can have different saddle heights from each other.

[0036] According to one embodiment of the stent graft prosthesis, the first end and the second end of the tubular fabric member are each supported by a combination of ring stents. Such a combination of ring stents each consists of two cooperating ring stents of different configurations. Optionally, the continuous tubular fabric member extending between the first end and the second end is supported by spaced-apart ring stents. These ring stents need not be the same as the combination of ring stents that support each end of the tubular fabric member.

[0037] The first end and the second end of the tubular fabric member are referred to herein as the "proximal" end and the "distal" end, respectively, and each means the end of the stent graft prosthesis that is closer to the heart and farther from the heart during placement.

[0038] In one embodiment of the stent graft prosthesis, the stent graft prosthesis employs, in each combination of ring stents, either an outer "saddle" shaped ring stent or a simple circular ring stent that overlaps and constrains an inner, more steeply sloped "saddle" shaped ring stent, and can address the potential problem of long-term vascular overexpansion due to the radial expansion force of the self-expanding ring stent. The overlapping combination of ring stents also results in the inner ring stent applying a radially directed force to hold the outer ring stent and the fabric of the tubular fabric member securely against the vessel wall, and placing the ring stents deployed against the vessel wall for sealing purposes in good parallel alignment.

[0039] In an embodiment, each of the two cooperating ring stents of different configurations that can be compressed into a folded shape can be compressed into a "saddle" shape having peaks and valleys. One of the two cooperating ring stents has an open lumen diameter D of the tubular fabric memberf has the above uncompressed diameter d 1 The other of the two cooperating ring stents has an open lumen diameter D of the tubular fabric member f which is larger than, and significantly larger than the uncompressed diameter d 1 One of the two cooperating ring stents having an uncompressed diameter d1 overlaps and restrains the other of the two cooperating ring stents having an uncompressed diameter d 2 without adhering to the latter. In such an embodiment, one of the two cooperating ring stents having an uncompressed diameter d 2 typically intersects over the other of the two cooperating ring stents having an uncompressed diameter d 1 at four intersections. Each intersection is in the region between the peaks and valleys of the ring stent having an uncompressed diameter d 2 2

[0040] In such an embodiment, one of the two cooperating ring stents having an uncompressed diameter d 1 can be identified as a ring stent (LS) having a "less steep saddle" shape, and the other of the two cooperating ring stents having an uncompressed diameter d 2 can be identified as a ring stent (S) having a "steep saddle" shape.

[0041] In an embodiment, the stent graft prosthesis can be branched, for example bifurcated.

[0042] ​​One of ordinary skill in the art will understand the following. That is, the tubular fabric member functions as a repair sleeve or liner and extends through and joins a weakened or missing portion of a natural blood vessel, and the stents disposed at the first and second ends function to position the tubular fabric member such that the tubular fabric member is retained after the treatment procedure is completed and the components of the delivery system are removed at the weakened or missing portion of the natural blood vessel. These stents disposed at the first and second ends, which function to position the tubular fabric member such that the tubular fabric member is retained after the treatment procedure is completed, need not be of the same design or configuration, as long as at least one end has two cooperating ring stents of different configurations, as recited in the claims.

[0043] In an embodiment, each of the two cooperating ring stents of different configurations has at least one portion attached to the fabric of the tubular fabric member. Each of the two cooperating ring stents of different configurations has at least one portion that makes sliding contact with the other portion of the two cooperating ring stents of different configurations. Thereby, each of the two cooperating ring stents of different configurations can be folded and deployed according to its characteristics. However, the overlapping portions of the two cooperating ring stents of different configurations improve the profile and shape of the ends of the tubular fabric body. As a result, the performance of the stent graft prosthesis is improved.

[0044] The ring stent, in its initial state, i.e., before being folded, has the widest lateral dimension which is conveniently referred to as the "diameter" herein, and may be a circular ring that is not fully deformed in some cases, or a mainly circular ring having at least one, preferably two, shaped parts such as a flexible hinge part or a sinusoidal part (as disclosed hereinafter in this specification). When folded, a stent folded compactly for delivery purposes is provided within a delivery restraint such as a sheath in which the "diameter" is reduced so that the stent can pass through the narrow lumen of a tubular blood vessel. In such a compactly folded state, at least one, at least the sinusoidal part of the ring stent may be axially displaced along the longitudinal axis of the tubular fabric member. Therefore, the "diameter" of the ring stent is considered in terms of whether it is in the shape compacted for delivery into a restraint such as a removable sheath that is attached to the tubular fabric member so as to assume the folded shape which is the state where its original fold is released, or in the deployed configuration that supports the open end of the tubular graft prosthesis in the lumen of the blood vessel.

[0045] The shaping of "shape memory" materials is generally known. This shaping usually involves the manipulation of the material around a shaping material which is a cylindrical or polygonal mandrel in the case of the wire-shaped rings of the present invention under a heat treatment process. This may include the controlled and continuous application of a heating stage and a quenching stage. For example, U.S. Patent Application Publication No. 20090309273 discloses a method for fabricating a self-expanding tubular stent from a shape memory alloy.

[0046] In an embodiment, in a combination of two cooperating ring stents of different configurations, at least one of the two cooperating ring stents of different configurations that can be compressed into a folded shape has an uncompressed diameter that exceeds the open lumen diameter D f of the tubular fabric member.

[0047] In an embodiment, in a combination of two cooperating ring stents of different configurations, each of the two cooperating ring stents of different configurations that can be compressed into a folded shape has an uncompressed diameter equal to or greater than the open lumen diameter D of the tubular fabric member. f equal to, or f has an uncompressed diameter that exceeds the open lumen diameter D.

[0048] In an embodiment, in a combination of two cooperating ring stents of different configurations, one of the two cooperating ring stents of different configurations that can be compressed into a folded shape has a diameter that exceeds the diameter of the other of the two cooperating ring stents of different configurations that can be compressed into a folded shape.

[0049] Each of the two cooperating ring stents of different configurations that can be compressed into a folded shape can be compressed into a "saddle" shape having peaks and valleys. One (LS) of the two cooperating ring stents has an uncompressed diameter d greater than or equal to the open lumen diameter D of the tubular fabric member. f The other (S) of the two cooperating ring stents has an uncompressed diameter d that is greater than the open lumen diameter D of the tubular fabric member and significantly greater than the diameter d. 1 One (LS) of the two cooperating ring stents having the uncompressed diameter d overlaps the other (S) of the two cooperating ring stents having the uncompressed diameter d. f larger than, and 1 significantly larger than the diameter d 2 has. The uncompressed diameter d 1 has. One (LS) of the two cooperating ring stents having the uncompressed diameter d 2 overlaps the other (S) of the two cooperating ring stents having the uncompressed diameter d.

[0050] The folded shape can be such that a compressible ring stent is folded during compression to form a curved portion, with at least one elastic hinge portion, preferably two spaced elastic hinge portions, therebetween. Each of the elastic hinge portions can be shaped in a configured "V" shape. Alternatively, the folded shape can be such that a compressible ring stent is folded during compression to form a sinusoidal curved portion, and in some embodiments, can be in a "saddle" shape having peak and valley portions. The at least two, spaced elastic hinge portions can be in a configured "V" shape and can be disposed at positions diametrically opposed to the compressible ring stent. Shaping a portion of the ring stent into a V-shaped hinge portion can be achieved by heat curing.

[0051] The ring stent used to form a combination of two cooperating ring stents of different configurations can be selected from a radially compressible "Z" stent, or "zigzag" stent, a compressible ring stent, a compressible shaped ring stent, or a "saddle" shaped ring stent. In that case, the ring stent used can be selected from a range of sizes such that in a combination of two cooperating ring stents of different configurations, one of the ring stents is a "saddle" shaped ring stent (S) with a relatively steep gradient and the other is a "saddle" shaped ring stent (LS) with a relatively less steep gradient.

[0052] U.S. Patent No. 5,035,706 discloses an example of a radially compressible "Z" stent. U.S. Patent No. 9,993,329 discloses an example of a compressible "saddle" shaped ring stent.

[0053] U.S. Patent Application Publication No. 20170007391 discloses a stent graft of tubular shape. In this stent graft, a plurality of elastic rings are intermittently arranged in the axial direction of the tubular shape across both ends of the graft, and each elastic ring is accommodated in a delivery sheath deformed into a "saddle shape". The stent graft includes a thin auxiliary elastic wire that is less rigid than the elastic rings. The auxiliary elastic wire is directly connected to the plurality of elastic rings arranged at the ends or is connected via the graft. The auxiliary elastic wire is an endless loop formed from continuously connected first and second wire elements. Therefore, the auxiliary elastic wire surrounds the graft endlessly and has recesses and protrusions connected by the wire elements for tilt stability due to regular intervals. However, the auxiliary elastic wire does not cross over the end elastic rings in the graft. Therefore, the stent graft disclosed in U.S. Patent Application Publication No. 20170007391 is fundamentally different from that of the present disclosure.

[0054] At least one of two cooperating ring stents of different configurations compressible into a folded shape can be a radially compressible Z-stent. The other of the two cooperating ring stents of different configurations compressible into a folded shape can be folded into a "saddle" shape having peak portions and valley portions when compressed. In some embodiments, the other cooperating ring stent overlaps the "saddle" shaped ring stent. The cooperating ring stents are attached to the tubular fabric member at selected discrete points but can move freely relative to each other at the intersection points. Thereby, the cooperating rings can be compactly folded into the delivery catheter and then undergo different levels of deformation necessary for deployment.

[0055] One of two cooperating ring stents of different configurations that can be compressed into a folded shape can be a radially compressible shaped ring stent with a hinge portion such as a V-shaped portion. The other of two cooperating ring stents of different configurations that can be compressed into a folded shape can be folded into a "saddle" shape having peaks and valleys upon compression. In some embodiments, the "saddle" shaped ring stent is outermost and attached to a tubular fabric member and intersects the other cooperating shaped ring stent. The cooperating shaped ring stents can be compressed to a smaller diameter by radial crimping and are selectively attached to the tubular fabric member such that the attachment points are each in a fabric region behind the quarter peak of the saddle shaped ring stent. This allows for sufficient relative movement between the rings and can accommodate the desired level of deformation necessary to compactly fold for delivery into a catheter and subsequent deployment.

[0056] The shaped ring stent can be selectively attached to the tubular fabric member at points corresponding to the fabric regions associated with the peak portions of the "saddle shape" ring stent. This attachment is made behind such peak portions. By doing so, the complete deployment of the "saddle shape" ring stent allowed within the tubular fabric member is not hindered by the presence of the shaped ring stent. The preferred rounded peripheral shape of the "saddle shape" ring stent within the tubular fabric member is facilitated by the presence of the shaped ring stent.

[0057] In other embodiments, at least one of two cooperating ring stents of different configurations that can be compressed into a folded shape can be compressible into a "saddle" shape having peaks and valleys of a relatively steep "saddle" height. The other of two cooperating ring stents of different configurations that can be compressed into a folded shape can be compressible into a "saddle" shape having peaks and valleys that are not relatively steep.

[0058] As used herein and referred to above, the "saddle" shape refers to a generally circular ring stent formed of a material having sufficient elasticity to be reversibly folded into a form that is compactly packaged within a restraint sleeve or sheath. The ring stent during compression deforms in a predictable manner. As a result, creases are formed and a first pair of diametrically opposed points on the circumference of the ring are displaced in a uniaxial direction. On the other hand, a second pair of diametrically opposed points located centrally on the circumference between the first pair are displaced in the axial direction opposite to the first pair, forming a symmetric "saddle" shape. In any embodiment using such a "saddle" shaped ring stent, the ring stent can be configured to be folded to form two peaks and two valleys. A shape memory material such as nitinol (nickel-titanium alloy) can be used to "memorize" the "saddle" shape. Alternatively, the "saddle" shape can simply be held in the desired shape by selectively attaching the "saddle" shaped ring stent to the fabric of a tubular fabric member, for example by suturing at least the peak and valley portions to the fabric.

[0059] Such a "saddle" shaped ring stent can be formed of a continuous loop of an elastic material (such as strands or fibers of nitinol or PEEK) deformable into a sine wave (saddle) shape as described above. The "saddle" shape can be shaped onto the elastic material ring stent by forming it on a cylindrical or polygonal mandrel.

[0060] These "saddle" shaped stents can have a "saddle" height expressed as a ratio to the open lumen diameter D of the graft tubular fabric member of the "saddle" height. In the case of a "steep saddle" ring, from 1:2.5 to 1:0.9 (i.e., the ring saddle height is the diameter D of the fabric tube) f to fIt can be in the range of a ratio from 40% to 110% (of f ). Or, in the case of a "saddle" - shaped ring stent that is not a steep gradient, it can be in the range of a ratio from 0 (i.e., a substantially flat or undeformed planar ring) to 1:2 (i.e., 0 to 50% of the diameter of the graft tubular fabric).

[0061] In this specification, for ease of explanation, it is intended to distinguish different ring stents used in a combination of two cooperating ring stents of different configurations, and refers to a compressible ring stent that adopts a "saddle" shape when folded as a "saddle" - shaped ring stent. The other shaped - set ring stent used in a combination of two cooperating ring stents of different configurations, for example, formed of shaped - set parts such as flexible hinge parts or separated sinusoidal parts, is simply referred to as a "shaped - set" ring and is generally or specifically described as having, for example, a heat - cured hinge part depending on the situation. Additionally, a ring stent formed from a straight - shaped - set wire into an undeformed circular stent is simply referred to as a "ring stent". Each ring stent can be formed by co - winding a plurality of wire filament strands from 2 to 120 or more. Wires of any diameter that maintain the required elasticity can be used. The appropriate diameter of the wire can be selected from the range of 0.05 mm to 2 mm, for example, from 0.5 mm to 1 mm.

[0062] In an embodiment using a "saddle" - shaped ring stent attached to at least one of the first end and the second end of the tubular fabric member to form a combination of two cooperating ring stents of different configurations, one of the "saddle" - shaped ring stents has a "saddle" height considered a "steep gradient", i.e., the diameter D f of the tubular fabric member, within the range of 40 - 110%. The other has a "saddle" height considered "not a steep gradient", i.e., the diameter D fIt has a "saddle" height within the range of 0 to 50% thereof. These ranges are relative differences in the configuration of the folded or compressed ring stent that form a combination of two cooperating ring stents, and are effective for that purpose. Therefore, these ranges are representative and non-limiting guidelines.

[0063] In other embodiments, one of the two cooperating ring stents of different configurations that can be compressed into a folded shape can be a shaped ring stent having at least one "V"-shaped flexible hinge portion. Optionally, the shaped ring stent can have more than one "V"-shaped flexible hinge portion. Otherwise, the shaped ring stent can have curved portions on both sides of at least one shaped "V"-shaped portion or between more than one "V"-shaped flexible hinge portion. If two "V"-shaped flexible hinge portions are formed in the shaped ring stent, they can be arranged at positions facing each other in the diameter direction of the shaped ring stent.

[0064] In an embodiment, at least one of the two cooperating ring stents of different configurations that can be compressed into a folded shape is at least partially disposed within the other of the two cooperating ring stents of different configurations that can be compressed into a folded shape.

[0065] In an embodiment, the shaped ring stent is compressible into a radially folded shape and is radially expandable within the open cavity diameter D f of the tubular fabric member. The shaped ring stent is disposed on the end of the tubular fabric member such that a portion of the shaped ring stent extends beyond the length L f of the tubular fabric member and is not covered by the fabric of the tubular fabric member. That is, that portion is exposed as a bare stent. Optionally, that portion is covered or coated with a material that reduces the trauma of the exposed portion to the natural blood vessel wall that contacts during the circulation of the pulsatile flow.

[0066] In an embodiment, the "V"-shaped portion of the shaped ring is within the length L of the tubular fabric member f and the curved portion extends beyond the length L of the tubular fabric member f of the tubular fabric member

[0067] In an embodiment, the shaped ring stent is at least partially disposed within a ring stent compressible into a "saddle" shape having a peak portion and a valley portion

[0068] In an embodiment, the tubular fabric member has a substantially circular perimeter at each of a first end and a second end. The ring stent compressible into a "saddle" shape is attached to the fabric of the tubular fabric member at a plurality of points around one of the first end and the second end. The shaped ring stent is selectively attached to a fabric portion of the tubular fabric member to enable sliding across the shaped ring stent while the ring stent compressible into a "saddle" shape having a peak portion and a valley portion compresses and expands (folds and the fold is released).

[0069] In an embodiment, each of two cooperating ring stents compressible into a folded shape can be compressible into a "saddle" shape having a peak portion and a valley portion. One of the two cooperating ring stents has an uncompressed diameter d that is greater than or equal to the open lumen diameter D of the tubular fabric member f The other of the two cooperating ring stents has an uncompressed diameter d that is greater than the open lumen diameter D of the tubular fabric member and significantly greater than the uncompressed diameter d 1 One of the two cooperating ring stents having an uncompressed diameter d f has an uncompressed diameter d 1 that is greater than the open lumen diameter D of the tubular fabric member and significantly greater than the uncompressed diameter d 2 One of the two cooperating ring stents having an uncompressed diameter d 1 has an uncompressed diameter d 2Overlaps with the other of two cooperating ring stents having it, and constrains the latter without adhering to it. A combination of two cooperating ring stents of different configurations can be maintained in a cooperating relationship by selectively attaching each of the two cooperating ring stents to the fabric of a tubular fabric member. Alternatively, the cooperating relationship can also include selective attachment between each of the two cooperating ring stents at intersections in the curved regions between the "peaks" and "valleys" of a steeply sloped "saddle" shaped ring stent.

[0070] In an embodiment, a deployed flat ring or a "saddle" ring stent of a shallower height provides radial constraint to a steeply sloped height "saddle" ring stent. As a result, in use for deployment within a damaged blood vessel, the stent graft prosthesis device will only open up to a limited extent determined by the overlying flat (planar) ring or non-steeply sloped "saddle" ring stent during deployment. This provides a constraint and can reduce the potential problem of long-term overexpansion of the device within the damaged blood vessel.

[0071] Additionally, in the overlapping stent configuration proposed herein, the inner steeply sloped height "saddle" ring stent biases the overlapping outer flat or shallow height "saddle" ring stent against the blood vessel wall. Therefore, the ring stents are well aligned parallel within the blood vessel wall to provide sufficient sealing for the intended purpose within the treated blood vessel.

[0072] As disclosed herein, similar advantages can be achieved with other combinations. By using a shaped "hinged" ring stent in combination with a "saddle" shaped end ring stent configured as an outer ring stent that slidably intersects a portion of the shaped ring stent, the shaped ring stent can be deployed to expand radially and perpendicular to the native blood vessel wall being repaired. This radial expansion causes the "saddle" shaped end ring stent to assume a desired circular cross-sectional shape while maintaining a shallower "saddle" shape compared to its compressed steep "saddle" shape. Thus, the inner shaped ring prevents the outer "saddle" shaped end ring stent from distorting into a so-called "petal" shape or "elliptization" deformation that is observed when only the "saddle" shaped end ring is deployed. Such "elliptization" is undesirable because it can lead to overexpansion of the blood vessel (risk of excessive tension in the native blood vessel wall) and potentially to movement of the prosthesis device from the repair site after long-term implantation.

[0073] In all embodiments, the ring stent can be further compressed into a compact configuration for delivery, for example, within a sheath that constrains the compressed compact ring stent until release at the treatment site is required. It is known to use a removable sheath to constrain the prosthesis device in a compact configuration for delivery purposes. Such use is described, for example, in U.S. Patent Application Publication No. 2011 / 196472 and U.S. Patent Application Publication No. 2013 / 178925.

[0074] The ring stents described herein enable a stent graft formed from a tubular fabric material to be supported in an open lumen configuration by self-expansion of the ring stent after delivery constraints such as a sheath are removed.

[0075] In an embodiment, at least one of the first end and the second end of the tubular fabric member can be supported by a combination of two cooperating ring stents of different configurations. Each of the two cooperating ring stents of different configurations is compressible into a folded shape. The stent graft prosthesis can optionally be supported by additional stents over its length. When the stent graft prosthesis is in its deployed shape within a natural blood vessel, none of the optional additional stents contacts any of the two cooperating ring stents of different configurations in a combination of two cooperating stents of different configurations.

[0076] In an embodiment, the stent graft prosthesis has at least one, optionally one each, of the first end and the second end of the tubular fabric member supported by a combination of two cooperating ring stents of different configurations. Each of the two cooperating ring stents is compressible into a folded "saddle" shape. One of the ring stents of the combination has a "saddle" shape with a steeper gradient than the other ring stent of the combination of two cooperating ring stents of different configurations.

[0077] In an embodiment, one of the two cooperating ring stents of different configurations at each of the first end and the second end of the tubular fabric member can have a protruding portion of the stent that extends beyond the fabric of the tubular fabric member. This protruding portion can be a curved bare metal portion that is exposed beyond the length L f of the tubular fabric member. Alternatively, the protruding portion can be optionally covered or coated with a material that reduces trauma to the natural blood vessel wall that contacts when the stent graft prosthesis is deployed within the lumen of the natural blood vessel.

[0078] Next, preferred embodiments will be described by way of example only with reference to the following drawings.

Brief Description of the Drawings

[0079]

Figure 1

Figure 2A

Figure 2B

Figure 3A

Figure 3B

Figure 3C

Figure 4A

Figure 4B

Figure 4C

Figure 5

Figure 6A

Figure 6B

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11A

Figure 11B

Figure 12A

Figure 12B

Figure 12C

[0080] Referring to FIGS. 1, 2A and 2B, a stent graft prosthesis 10 according to a first embodiment is shown. As shown, the stent graft prosthesis 10 includes a tubular fabric member 12. The tubular fabric member 12 includes a first end 14 and a second end 16. The length (L f ) of the tubular fabric member 12 is the longest dimension of the continuous tubular fabric aligned with the longitudinal axis of the tubular fabric member 12 and extends between the first and second ends 14, 16. The length (L f ) is the longest dimension of the continuous tubular fabric aligned with the longitudinal axis of the tubular fabric member 12. The tubular fabric member 12 has an open lumen diameter D f .

[0081] In the illustrated example, the first end 14 of the tubular fabric member 12 is supported by a combination of two cooperating ring stents 18a, 18b. These stents are each compressible into a folded shape. The cooperating ring stents comprise a first ring stent 18a and a second ring stent 18b. Both the first and second ring stents 18a, 18b of the illustrated example are "saddle" shaped stents having peak and valley portions 20a, 20b. The first and second ring stents 18a, 18b each have the "saddle height" defined above.

[0082] As shown, the first and second ring stents 18a, 18b are disposed outside the tubular fabric member 12. The first and second ring stents 18a, 18b each have a diameter with the fold unfolded that exceeds the open lumen diameter D of the tubular fabric member 12 f By this, as best shown in FIG. 1, the first end 14 of the tubular fabric member 12 can be biased to open upon deployment. As shown, the first ring stent 18a is at least partially disposed within the second ring stent 18b. Thus, when the combination of ring stents 18a, 18b is deployed, it supports the first end 14 of the tubular fabric member and facilitates sealing with a healthy portion of the native blood vessel when deployed within the blood vessel.

[0083] As shown in this illustrated example, the first and second ring stents 18a, 18b have different configurations. For example, as shown, the deployed diameter of the second ring stent 18b exceeds the deployed diameter of the first ring stent 18a. However, when the fold is unfolded and not attached to the tubular fabric member 12, the first ring stent 18a has a larger diameter than the second ring stent 18b and, as shown, when constrained within the second ring stent 18b and the tubular fabric member 12, the first ring stent 18a assumes a steep "saddle" height. Also, the second ring stent 18b has a much lower (more gently sloped) "saddle" height than the first ring stent 18a.

[0084] In an alternative example, the second ring stent 18b is replaced by a ring stent that unfolds from a compressed and folded "saddle"-shaped stent into a "flat" circular ring stent. This ring stent intersects over the more steeply sloped "saddle"-shaped ring 18a at four points in the region between the "peaks" and "valleys" of the steeply sloped "saddle"-shaped ring stent 18a.

[0085] Referring again to FIG. 1, the first and second ring stents 18a, 18b are each fixed to the tubular fabric member 12, for example, by suture threads. The manner in which the first and second ring stents 18a, 18b are fixed to the tubular fabric member 12 may be the same as that shown with respect to the second embodiment of FIGS. 3A and 3B. Materials suitable for suture threads include nylon, polypropylene, silk, and polyester in the form of braids or monofilaments. The first and second ring stents 18a, 18b can be made expandable with a balloon (e.g., a PALMAZ stent made of rigid stainless steel wire), but can also be self-expanding and formed of a shape memory material such as nitinol (nickel-titanium alloy).

[0086] The stent graft prosthesis 10 is supported over its entire length by additional stents 22. However, as shown, none of these stents 22 are in contact with each of the first and second ring stents 18a, 18b. The additional stents 22 in this embodiment are also "saddle"-shaped stents with peak and valley portions. In the example shown, the cooperating ring stents 18a, 18b are provided at the first end 14 of the tubular fabric member 12. The circular end stent 24 is provided at the second end 16 of the tubular fabric member 12. However, alternatively, the combination of the cooperating ring stents 18a, 18b can also be provided at the second end 16 of the tubular fabric member 12. The cooperating ring stents 18a, 18b act to support the first end of the tubular fabric member radially.

[0087] Figures 3A, 3B, and 3C show a second embodiment of the prosthesis 100 according to the present invention. The second embodiment is a modified version of the first embodiment. In this embodiment, additional stents that support the tubular fabric member 112 over its entire length comprise a plurality of combinations of cooperating ring stents 118a, 118b. The ring stents 118a, 118b are spaced along the length of the tubular fabric member.

[0088] Figures 4A, 4B, and 4C show a third embodiment of the prosthesis 200 according to the present invention. The third embodiment is a modified version of the first embodiment. Here, as in the first embodiment, both the first and second ring stents 218a, 218b are "saddle-shaped" stents. In this embodiment, the first ring stent 218a is disposed inside the second ring stent 218b at the first end 214 of the tubular fabric member 212. Thus, the portion 230 of the first ring stent 218a extends beyond the length of the tubular fabric member 212. Optionally, the first ring stent 218a is formed from metal and shaped into a "saddle" shape on a cylindrical or polygonal mandrel. Otherwise, the desired "saddle" can be formed by a ring folding operation or by sewing the "saddle" shape onto the fabric of the tubular fabric member 212 at a selected location. As best shown in FIG. 4B, only the valley portion 220b of the first ring stent is fixed inside the tubular fabric member 212. The portion 230 of the first ring stent that extends beyond the tubular fabric member 212 is the peak portion of the first ring stent 218a.

[0089] Referring to FIGS. 5, 6A, and 6B, a prosthesis 300 according to a fourth embodiment of the present invention is shown. Similar to the first embodiment, the stent graft prosthesis 300 comprises a tubular fabric member 312 having first and second ends 314, 316, and a combination of two cooperating ring stents 318a, 318b of different configurations. Further, the tubular fabric member 312 has an open lumen diameter D, similar to the first embodiment. fIt has. However, the combination of the two cooperating ring stents 318a, 318b is arranged differently from the first embodiment. This combination will be described below.

[0090] The cooperating ring stents comprise a first and a second ring stent 318a, 318b. The first ring stent 318a is a shaped ring stent having at least one "V"-shaped portion 332. The second ring stent 318b is a "saddle"-shaped ring stent having "hill" and "valley" portions 350, 351. The first ring stent 318a is disposed inside the second ring stent and has a diameter exceeding the open lumen diameter D f As shown in the figure, the shaped stent 318a comprises two "V"-shaped hinge portions 332. These are separated from each other by a curved portion 334 and attached to the fabric of the tubular fabric member 312 so as to be in diametrically opposed positions within the open lumen diameter D f Furthermore, the shaped stent 318a comprises a portion 330 extending beyond the tubular fabric member 312.

[0091] In the embodiments of FIGS. 5, 6A, and 6B, the combination of cooperating ring stents 318a, 318b is provided at the first end 314 of the tubular fabric member 312. The (shaped) first ring stent 318a is fixed to the inner surface of the tubular fabric member 312. The (saddle-shaped) second ring stent 318b is fixed around the first end 314 of the tubular fabric. The first and second ring stents 318a, 318b are each fixed to the tubular fabric member 312 with suture threads. As a result, for example, while folding the stent graft prosthesis 300 to compress it for delivery into the lumen of a natural blood vessel, or while deploying the stent graft prosthesis 300 within the lumen of a natural blood vessel, the first ring stent 318a can slide over the second ring stent 318b as needed. This relative sliding is achievable when the (shaped) first ring stent 318a is fixed to the inner surface of the tubular fabric member 312 by a "V"-shaped hinge portion 332 near the peak portion 350. Thus, the cooperating ring stents 318a, 318b are separately fixed to the tubular fabric member 312, can be folded compactly, and can then be opened for simultaneous deployment with independent relative movement.

[0092] FIG. 7 shows the second ring stent 318b in a compressed state and a deployed state. As shown, in the deployed state, the "saddle" diameter of the second ring stent 318b is much larger than in the compressed state. Further, the "saddle" height of the second ring stent 318b is much higher in the compressed state than in the deployed state.

[0093] Figure 8 shows a tubular fabric member 312 to which a second ring stent 318b is attached, and a first ring stent 318a separated from the tubular fabric member 312. Figure 8 also shows a stent graft prosthesis 300. The stent graft prosthesis 300 is formed when the first ring stent 318a is fixed to the inner surface of the tubular fabric member 312 such that the first ring stent 318a is disposed within the second ring stent 318b. As described above, the (shaped) first ring stent 318a is fixed only to the inner surface of the tubular fabric member 312 by a "V"-shaped hinge portion 332 in the vicinity of the peak portion 350. As a result, independent relative movement is possible by one stent sliding across the contact point with the other stent.

[0094] Figure 9 shows an end of a stent graft prosthesis 400 according to a fifth embodiment of the present invention. The fifth embodiment is a modified version of the first embodiment. Here, as in the first embodiment, the stent graft prosthesis 400 includes a tubular fabric member 412 having first and second ends supported by a combination of ring stents having different configurations. For purposes of illustration, the first end 414 of the tubular fabric member 412 is held in an open state by a combination of two cooperating first and second ring stents 418a, 418b of different configurations that function in the same manner as the combination of the first embodiment described above. The ring stent 418b fixed to the outer surface of the tubular fabric member 412 is a "saddle"-shaped stent. However, in contrast to the first embodiment, the first ring stent 418a disposed within the second ring stent has a plurality of "V"-shaped hinge portions connected to each other. The first ring stent 418a can be referred to as a "Z"-shaped stent that compresses and expands radially. The "Z"-shaped stent is known per se to those skilled in the art. Similar to the embodiments of Figures 5, 6, and 8, the "Z"-shaped stent is attached by fixing the "V"-shaped hinge portion only to the inner surface of the tubular fabric member 412 in the vicinity of the peak portion of the second ring stent 418b. As a result, independent relative movement is possible by one stent sliding across the contact point with the other stent.

[0095] FIG. 10 shows a stent graft prosthesis 100 deployed within a transparent curved tube within a test apparatus to simulate the performance in a curved native blood vessel 50. When the stent graft prosthesis 100 is deployed from a compressed state within the blood vessel 50, the first ring stent 118a opens without being hindered by the second ring stent 118b because each ring stent is selectively fixed to the fabric of the tubular fabric member 112 and is slidable at the point of contact. The second ring stent 118b acts to restrain the first ring stent 118a such that the tubular fabric member 112 has a circular cross-section and holds it. This means that problems such as "elliptization" of the stent graft prosthesis 100, which are observed when using a single "saddle"-shaped stent, do not occur, and thus it is ensured that the position of the stent graft prosthesis within the blood vessel 50 is radially stable over the long term. The use of a steep-gradient "saddle"-shaped ring stent is beneficial for stability and radial opening (when deployed vertically), and it can be seen that the use of a non-steep-gradient (or circular) ring stent is beneficial for achieving sealing juxtaposition.

[0096] FIGS. 11A and 11B show successive steps of the deployment method of the stent graft prosthesis 300 of the embodiments of FIGS. 5, 6A, and 6B, observable in the transparent tube of the test apparatus. The test apparatus determines the angular change at the proximal end of the tubular graft prosthesis when it is introduced into the arch-shaped portion and has graduations that make clearly visible the extent of contact between the proximal end of the tubular graft prosthesis and the surface of the tube. The test apparatus simulates the introduction of the tubular graft prosthesis into a native blood vessel lumen such as the lumen of the aortic arch.

[0097] In patients undergoing endovascular aortic repair of the thoracic aorta, it has been observed that structural changes and incomplete parallel placement of the endograft in the aortic arch may occur. This type of problem is referred to as the "bird-beaking" effect.

[0098] The present disclosure addresses such problems by providing various embodiments that are combinations of two cooperating ring stents of different configurations. The characteristics of the cooperating ring stents act together to avoid or mitigate these problems.

[0099] In the use of one embodiment disclosed herein, the proximally shaped ring automatically centers within the curved lumen of the native blood vessel when the proximal end of the tubular graft prosthesis device is withdrawn from its compact delivery configuration. By this action, the proximal sealing stent can be favorably and parallelly deployed without "bird beaking", achieving stability. This is readily achievable with the disclosed combination of stents because the shaped stent first exits the sheath and contacts the outer wall of the native blood vessel to be repaired. As the shaped stent opens and reacts against the vessel wall, it pushes the proximal end of the tubular graft prosthesis device to deploy centrally within the lumen of the native blood vessel. This means that the other ring stent required for sealing is positioned centrally within the lumen in a stable, symmetric "saddle" shape. This ensures that the proximal end of the tubular graft prosthesis device is favorably parallelly deployed against the surrounding vessel wall without bird beaking at the inner curve of the arch portion.

[0100] In one embodiment of a tubular graft prosthesis device, the ring stent is attached to the circular end cloth of the tubular graft member around its perimeter to form a stent graft. This stent graft can be changed to a diameter smaller than the diameter of the tubular graft prosthesis by folding the ring stent into a steeply sloped saddle shape having "hill" and "valley" portions, and compactly packaged within a delivery sheath. Subsequently, when the delivery sheath is removed, the folded "saddle" ring opens from the compact steeply sloped "saddle" shape to a non-steeply sloped "saddle" shaped ring stent or a circular ring stent in response to the restraint imposed by the contacting wall of the natural blood vessel into which the tubular graft prosthesis device is delivered. Although many of these are "normal" procedures, the effect of introducing a shaped ring stent in combination with a "saddle" shaped stent is remarkable. In the disclosed embodiment, the shaped ring stent has two "V" shaped hinge portions connected by a curved portion. As a result, the "V" shaped hinge portions are disposed diametrically on the cloth wall of the tubular graft member having a generally cylindrical shape. The shaped stent changes from one diameter to another smaller diameter by radial deformation when pushed into a compact delivery configuration. The shaped ring stent is attached to the graft cloth in the region behind one quarter of the two ring hills by two opposing "V" shaped hinge portions and is not attached to the graft cloth in the region of one quarter of the two ring valleys. When the branched limbs of the "V" shaped hinge portion are sewn and attached to the cloth, the shaped stent intersects the ring stent at (at least) four points. Each point is on the curved portion between the hill and valley of the "saddle" shaped ring stent. The "saddle" shaped ring stent can slide freely over the shaped stent where these intersections occur. This arrangement allows the stent graft to be compressed or expanded despite the different deformation modes of the stents attached to the stent graft.

[0101] In one embodiment, the shaped ring stent has a shape comprising two "hinge" elements (each having one peak portion and two valley portions) disposed on the ring stent such that a maximum width dimension (≈ diameter) exists between their positions, and two curved portions extending in the proximal direction between their opposing positions. The "hinge" portions are used for attachment to the fabric in the area behind one-quarter of the ring peak. Each hinge peak is disposed behind the ring valley. The curved portions are exposed beyond the ends of the graft fabric above one-quarter of the ring valley, forming "bare metal" stent elements in these areas. This shape allows for non-traumatic contact with the wall of the natural blood vessel being repaired by the curved bare metal stent, i.e., the stent not covered by the graft fabric. To reduce trauma due to contact, the exposed stent elements can optionally be covered or coated with a material, sutured, or otherwise treated.

[0102] In multiple embodiments, two cooperating ring stents of different configurations can each conveniently be manufactured from the same material, e.g., the same memory material such as nitinol (NiTi alloy) wire.

[0103] Embodiments of the stent graft prosthesis according to the present invention as disclosed provide the following advantages. 1. When the currently disclosed stent graft prosthesis is deployed at the target treatment site within the lumen of a blood vessel, the cooperating ring stents provide stable positioning within the blood vessel without the aid of the positioning mechanism of the delivery system. 2. By combining two ring stents instead of just one ring, the second ring stent can restrict how much (radially) the first ring stent can open during deployment. This means that over time as the blood vessel remodels under the chronic outward force of a self-expanding stent, the stent graft prosthesis will only open within the range allowed by the second ring stent, thereby avoiding the problem of long-term overexpansion of the blood vessel. 3. Also, in the stent arrangement of the present invention, since the first ring stent applies a radial force to hold the second ring stent against the blood vessel wall, the parallel placement of the stent with respect to the blood vessel wall is improved (the adhesion of the stent to the blood vessel wall is improved). 4. The cooperating ring stents fit well radially within the blood vessel even when the delivery system is off - center and / or when the blood vessel is curved. 5. When the cooperating stents are deployed, they open radially and assume a stable cylindrical shape perpendicular to the blood vessel wall. 6. "Bird beak" does not occur during the deployment of the stent - graft prosthesis of the present invention. 7. When using the stent - graft prosthesis of the present invention, since there is no sharp tip at the proximal (leading during delivery) end of the stent - graft prosthesis, it has a non - traumatic effect on the blood vessel wall of the blood vessel in which it is placed. 8. The above - mentioned non - traumatic effect can be achieved with a shaped ring stent having a shaped hinge portion and a curved portion between the hinge portions. The curved portion projects beyond the fabric of the tubular fabric member and provides a proximal apex having a radius larger than the distal apex of the hinge portion. The hinge portion is fixed only at a selected portion within the tubular fabric member (Figs. 5 and 8). Alternatively, in an embodiment using a saddle ring stent, a steep - gradient saddle - shaped ring stent can be placed at the end of the tubular fabric member, within a non - steep - gradient saddle ring stent, or within or on a flat ring stent. As a result, the "hill" of the curve of the steep - gradient saddle - shaped ring stent projects beyond the end of the tubular fabric member (Figs. 4a, 4b, and 4c). 9. The stability of the end ring stent can be achieved only by another ring stent arranged to cross or traverse over the end ring stent to be stabilized. 10. The radial stability achievable to maintain the patency of the lumen of the stent - graft prosthesis can be achieved by either one of two cooperating ring stents of different configurations crossing over the other of the two cooperating ring stents of different configurations, either on the inside or the outside.

[0104] The following paragraphs relate to embodiments and alternative configurations, or preferred aspects, of the disclosed stent graft prosthesis. (a). The stent graft prosthesis comprises at least a first end and a second end, and a length L extending between the first end and the second end f and an open lumen diameter D f and a tubular fabric member having the same. At least one of the first end and the second end of the tubular fabric member is supported by a combination of two cooperating ring stents of different configurations. Each of the two cooperating ring stents of different configurations is compressible into a folded shape to provide a compact delivery shape of the stent graft prosthesis. The tubular fabric member is attached at selected points to each of the two cooperating ring stents of different configurations. If the tubular fabric member is supported by additional stents over its entire length, when the stent graft prosthesis is in the deployed shape, none of the additional stents contacts any of the two cooperating ring stents of different configurations in the combination of the two cooperating ring stents of different configurations. (b). The stent graft prosthesis comprises at least a first end and a second end, and a length L extending between the first end and the second end f and an open lumen diameter D f and a tubular fabric member having the same. At least one of the first end and the second end of the tubular fabric member is supported by a combination of two cooperating ring stents of different configurations. Each of the two cooperating ring stents of different configurations is compressible into a folded shape to provide a compact delivery shape of the stent graft prosthesis. The tubular fabric member is attached to each of the two cooperating ring stents of different configurations at selected points. The two cooperating ring stents of different configurations can move freely relative to each other at a point where one of the two cooperating ring stents of different configurations intersects the other of the two cooperating ring stents of different configurations. One of the two cooperating ring stents of different configurations is restricted from overexpansion by the other of the two cooperating ring stents of different configurations. (c). The stent graft prosthesis according to paragraph (a) or paragraph (b), wherein at least one of the two cooperating ring stents of different configurations that is compressible into a folded shape has a diameter equal to the open lumen diameter D of the tubular fabric member f or a diameter greater than the open lumen diameter D of the tubular fabric member f . (d). The stent graft prosthesis according to paragraph (c), wherein one of the two cooperating ring stents of different configurations that is compressible into a folded shape has a diameter greater than the diameter of the other of the two cooperating ring stents of different configurations that is compressible into a folded shape. (e). The stent graft prosthesis according to any one of paragraphs (a), (b), (c) or (d), wherein one of the two cooperating ring stents of different configurations that is compressible into a folded shape is a shaped ring stent having at least one "V"-shaped hinge portion. (f). The stent graft prosthesis according to any one of paragraphs (a), (b), (c) or (d), wherein one of the two cooperating ring stents of different configurations that is compressible into a folded shape has more than one "V"-shaped hinge portion and a curved portion therebetween. (g). A stent graft prosthesis according to any one of paragraphs (a), (b), (c) or (d), wherein one of two cooperating ring stents of different configurations that can be compressed into a folded shape is a shaped ring stent having a plurality of connected "V"-shaped hinge portions and optionally a Z-stent configuration. (h). A stent graft prosthesis according to any one of paragraphs (e), (f) or (g), wherein the shaped ring stent is compressible into a radially folded shape and is radially expandable within the open lumen diameter D of the tubular fabric member. The shaped ring stent is disposed over the end of the tubular fabric member such that a portion of the shaped ring stent extends beyond the length L of the tubular fabric member and is not covered by the fabric of the tubular fabric member. f within. f (i). A stent graft prosthesis according to paragraph (h), wherein the "V"-shaped hinge portion of the shaped ring is within the length L of the tubular fabric member. f (j) A stent graft prosthesis according to any one of paragraphs (e), (f), (g) or (h), wherein the shaped ring stent having at least one "V"-shaped hinge portion is at least partially disposed within the other of two cooperating ring stents of different configurations, and the other of the two cooperating ring stents of different configurations is compressible into a "saddle" shape having peaks and valleys, and the shaped ring stent is attached to the fabric of the tubular fabric member at the peak of the "saddle" shaped ring stent by the "V"-shaped hinge portion or by each "V"-shaped hinge portion of the shaped ring stent (Figure 5). (k) The stent graft prosthesis described in paragraph (j), wherein the tubular fabric member has a substantially circular perimeter at each of the first end and the second end. A ring stent compressible into a "saddle" shape is attached to the fabric of the tubular fabric member at a plurality of points around one substantially circular perimeter of the first end and the second end. A cooperating shaped ring stent is selectively attached to a portion of the fabric of the tubular fabric member at the same end, and a ring stent compressible into a "saddle" shape having a peak portion and a valley portion is slidable over the shaped ring stent as needed. (l) The stent graft prosthesis according to any one of paragraphs (a), (b), (c), (d), (e), (f), (g), (h), (i), (j), or (k), wherein different configurations of two cooperating ring stents include one of the two cooperating ring stents of different configurations forming a ring stent having a relatively steep "saddle" shape as compared to the other of the two cooperating ring stents of different configurations. (m). The stent graft prosthesis according to any one of paragraphs (a), (b), (c) or (d), wherein each of two cooperating ring stents of different configurations compressible into a folded shape is compressible into a "saddle" shape having a peak portion and a valley portion. One of the two cooperating ring stents has an uncompressed diameter d f greater than or equal to the open lumen diameter D 1 of the tubular fabric member. The other of the two cooperating ring stents has an uncompressed diameter d f greater than the open lumen diameter D 1 of the tubular fabric member and significantly greater than the uncompressed diameter d 2 of the other. One of the two cooperating ring stents having an uncompressed diameter d 1 overlaps the other of the two cooperating ring stents having an uncompressed diameter d 2 and restrains the latter without adhering to it. (n). The stent graft prosthesis according to paragraph (m), wherein the uncompressed diameter d 1One of two cooperating ring stents having a non-compressed diameter d intersects the other of the two cooperating ring stents at four intersections, each intersection being in a region between the peaks and valleys of a ring stent having a non-compressed diameter d. 2 One of two cooperating ring stents having a non-compressed diameter d intersects the other of the two cooperating ring stents at four intersections, each intersection being in a region between the peaks and valleys of a ring stent having a non-compressed diameter d. 2 One of two cooperating ring stents having a non-compressed diameter d intersects the other of the two cooperating ring stents at four intersections, each intersection being in a region between the peaks and valleys of a ring stent having a non-compressed diameter d. (o). The stent graft prosthesis according to paragraph (m), wherein one of two cooperating ring stents having a non-compressed diameter d is in a "saddle" configuration, with its "valley" portion attached within the tubular fabric member and its "peak" portion attached to the fabric of the tubular fabric member so as to project beyond the length L of the tubular fabric member and not be covered by the fabric of the tubular fabric member. 2 (o). The stent graft prosthesis according to paragraph (m), wherein one of two cooperating ring stents having a non-compressed diameter d is in a "saddle" configuration, with its "valley" portion attached within the tubular fabric member and its "peak" portion attached to the fabric of the tubular fabric member so as to project beyond the length L of the tubular fabric member and not be covered by the fabric of the tubular fabric member. f (o). The stent graft prosthesis according to paragraph (m), wherein one of two cooperating ring stents having a non-compressed diameter d is in a "saddle" configuration, with its "valley" portion attached within the tubular fabric member and its "peak" portion attached to the fabric of the tubular fabric member so as to project beyond the length L of the tubular fabric member and not be covered by the fabric of the tubular fabric member. (p) The stent graft prosthesis according to any one of the preceding paragraphs, wherein one of the two cooperating ring stents at each of the first and second ends of the tubular fabric member has a curved portion exposed beyond the length L of the tubular fabric member. The exposed curved portion is a bare stent, or is covered with a material or coated to reduce traumatic contact with the native blood vessel. f (p) The stent graft prosthesis according to any one of the preceding paragraphs, wherein one of the two cooperating ring stents at each of the first and second ends of the tubular fabric member has a curved portion exposed beyond the length L of the tubular fabric member. The exposed curved portion is a bare stent, or is covered with a material or coated to reduce traumatic contact with the native blood vessel.

[0105] The illustrated embodiments are provided as non-limiting examples of stent graft prosthesis devices enabled by combinations of stents developed by the inventors. Modifications and improvements can be incorporated without departing from the scope of the invention as disclosed herein and claimed below.

Claims

**Claim 1** A stent graft prosthesis, At least a first end portion and a second end portion, and a length L extending between the first end portion and the second end portion ｆ and an open lumen diameter D ｆ and comprising a tubular fabric member having the same at least one of the first end and the second end of the tubular fabric member is supported by a combination of two cooperating ring stents of different configurations, and each of the two cooperating ring stents of different configurations is compressible into a folded shape to provide a compact delivery shape of the stent graft prosthesis, the tubular fabric member is attached to each of the two cooperating ring stents of different configurations at selected points, at least one of the two cooperating ring stents of different configurations is compressible into a folded "saddle" shape having two peaks and two valleys, the other of the two cooperating ring stents of different configurations intersects the at least one of the two cooperating ring stents of different configurations at four points, and each point is in a region between the peaks and valleys of the folded "saddle" shape, A stent graft prosthesis in which independent relative movement is possible by one stent sliding across the contact points with the other stent. **Claim 2** The stent graft prosthesis according to claim 1, wherein the other of the two cooperating ring stents of different configurations is also compressible into a folded "saddle" shape having two peaks and two valleys, and the peaks are axially aligned with the peaks of the at least one of the two cooperating ring stents of different configurations. **Claim 3** The stent graft prosthesis according to claim 1, wherein the other of the two cooperating ring stents of different configurations that is compressible into a folded shape is a shaped ring stent having at least one "V"-shaped hinge portion, and the "V"-shaped hinge portion is axially aligned with the peak of the at least one of the two cooperating ring stents of different configurations. **Claim 4** The stent graft prosthesis according to claim 1 or 3, wherein the other of the two cooperating ring stents of different configurations that is compressible into a folded shape is a shaped ring stent having more than one "V"-shaped hinge portion and a curved portion therebetween. **Claim 5** The stent graft prosthesis according to claim 1, wherein one of the two cooperating ring stents of different configurations that can be compressed into a folded shape is a Z-shaped stent having a V-shaped hinge portion fixed to the inner surface of the tubular fabric member, the Z-shaped stent is disposed within two saddle-shaped stents, and the V-shaped hinge portion is attached to the inner surface of the tubular fabric member only in the vicinity of the peak portion of the second ring stent.

6. A stent graft prosthesis according to any one of claims 1 to 5, wherein one of the two cooperating ring stents at at least one of the first end and the second end of the tubular fabric member has a curved portion exposed beyond the length L of the tubular fabric member ｆ The exposed curved portion is a bare stent or is covered or coated with a material to reduce traumatic contact with the native blood vessel. A stent graft prosthesis

7. The stent graft prosthesis according to claim 6, wherein the curved portion projects beyond the fabric of the tubular fabric member to provide a proximal apex having a radius larger than that of the distal apex of the hinge portion, and the hinge portion is fixed only at a selected portion within the tubular fabric member.

8. The stent graft prosthesis according to claim 6, wherein the curved portion is the peak of a saddle-shaped ring stent, and the peak projects beyond the end of the tubular fabric member.

9. A stent graft prosthesis according to any one of claims 1 to 8, wherein at least one of the two cooperating ring stents of different configurations that can be compressed into a folded shape has a diameter equal to the open lumen diameter D of the tubular fabric member ｆ or a diameter greater than the open lumen diameter D ｆ of the stent graft prosthesis.

10. The stent graft prosthesis according to claim 9, wherein one of the two cooperating ring stents of different configurations that can be compressed into a folded shape has a diameter exceeding the diameter of the other of the two cooperating ring stents of different configurations that can be compressed into a folded shape.

11. The stent graft prosthesis according to claim 3 or 4, wherein the shaped ring stent is compressible into a radially folded shape, and the open lumen diameter D of the tubular fabric member ｆ is radially expandable therein, and further, a part of the shaped ring stent extends beyond the length L of the tubular fabric member ｆ so as not to be covered by the fabric of the tubular fabric member, and is disposed on the end of the tubular fabric member. A stent graft prosthesis.

12. The stent graft prosthesis according to claim 11, wherein the "V"-shaped hinge portion of the shaped ring is within the length L of the tubular fabric member ｆ of the stent graft prosthesis.

13. The stent graft prosthesis according to any one of claims 1 to 4, wherein each of the two cooperating ring stents of different configurations that can be compressed into a folded shape is compressible into a "saddle" shape having a peak portion and a valley portion, and one of the two cooperating ring stents has a non-compressed diameter d ｆ greater than or equal to the open lumen diameter D of the tubular fabric member １ and the other of the two cooperating ring stents has a non-compressed diameter d ｆ greater than the open lumen diameter D of the tubular fabric member and significantly greater than the non-compressed diameter d １ and the one of the two cooperating ring stents having a non-compressed diameter d ２ overlaps and restrains the other of the two cooperating ring stents having a non-compressed diameter d １ without adhering to the latter, a stent graft prosthesis. ２ ​

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