Patent ID: 12213897

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention are directed generally to methods and devices for treatment of fluid flow vessels with the body of a patient. Treatment of blood vessels is specifically indicated for some embodiments, and, more specifically, treatment of aneurysms, such as, but not limited to, thoracic aortic aneurysms and abdominal aortic aneurysms. The present invention provides various graft assemblies for treatment of blood vessels, including modular graft assemblies, bifurcated graft assemblies, stent-graft assemblies, and combinations thereof.

Modular graft assemblies of the present invention may include a main graft assembly having a network of inflatable channels and a graft. One end the graft assembly may include one or more graft extensions, disposed at, for example, a distal end of the assembly. The graft assembly may be bi-furcated. The graft assembly may be formed from a supple graft material, such as ePTFE, having a main fluid flow lumen therein. The graft assembly may include porous PTFE which has no discernable node and fibril structure. The bifurcated graft assembly may also include an ipsilateral leg with an ipsilateral fluid flow lumen in communication with the main fluid flow lumen, a contralateral leg with a contralateral fluid flow lumen in communication with the main fluid flow lumen, and a network of inflatable channels disposed on the main graft member. For some embodiments, the main graft member may have an axial length of about 5 cm to about 10 cm, more specifically, about 6 cm to about 8 cm in order to span an aneurysm of a patient's aorta without engaging the patient's iliac arteries directly with the legs of the main graft member.

The inflatable channels of the network of inflatable channels may be disposed on any portion of the graft assembly including the main body portion, as well as the ipsilateral and contralateral legs. The network of inflatable channels may be configured to accept a hardenable fill material to provide structural rigidity to the main graft member when the network of inflatable channels are in an inflated state and the inflation material has been cured or hardened. Radiopaque inflation material may be used to facilitate monitoring of the fill process and subsequent engagement of graft extensions. The network of inflatable channels may also include at least one inflatable cuff disposed on a proximal portion of the main graft member which is configured to seal against an inside surface of a patient's vessel, such as the aorta. The network of inflatable channels may include at least one longitudinal fill channel in communication with channels at the proximal and distal ends of the device. Further, the network of inflatable channels may include a longitudinal channel in communication with circumferential channels at one end of the device.

A proximal anchor member may be disposed at a proximal end of the main graft member and secured to the main graft member. The proximal anchor member has a self-expanding proximal stent portion secured to a self-expanding distal stent portion with struts. Some embodiments of the struts may have a cross sectional area that is substantially the same as or greater than a cross sectional area of proximal stent portions or distal stent portions adjacent the strut. Such a configuration may be useful in avoiding points of concentrated stress in the proximal anchor member or struts which couple components thereof. For some embodiments, the proximal stent of the proximal anchor member further includes a plurality of barbs having sharp tissue engaging tips that are configured to extend in a radial outward direction in a deployed expanded state. For some embodiments, the proximal anchor member includes a 4 crown proximal stent portion and an 8 crown distal stent portion which may be made from a super-elastic alloy such as super-elastic nitinol (NiTi) alloy.

The graft extensions may be disposed at the distal end of the main graft member. For a bifurcated graft assembly, at least one ipsilateral graft extension having a fluid flow lumen disposed therein may be deployed with the fluid flow lumen of the graft extension sealed to and in fluid communication with the fluid flow lumen of the ipsilateral leg of the main graft member. In addition, at least one contralateral graft extension having a fluid flow lumen disposed therein may be deployed with the fluid flow lumen of the graft extension sealed to and in fluid communication with the fluid flow lumen of the contralateral leg of the main graft member. For some embodiments, the graft extensions may include an interposed self-expanding stent disposed between at least one outer layer and at least one inner layer of supple layers of graft material. The interposed stent disposed between the outer layer and inner layer of graft material may be formed from an elongate resilient element helically wound with a plurality of longitudinally spaced turns into an open tubular configuration. In some embodiments, the interposed stent may have a winding, undulating configuration from the proximal end to the distal end. For some embodiments, the interposed stent is may include a super-elastic alloy such as super-elastic NiTi alloy. In addition, the graft material of each graft extension may further include at least one axial zone of low permeability for some embodiments.

FIGS.1and2depict a main graft assembly10for the treatment of an aneurysm.FIGS.1and2depict a main graft assembly10that is non-bifurcated. As depicted inFIGS.1and2, the graft assembly10includes a main graft member12disposed between a proximal open end14and an opposed open distal end16. The main graft12has a wall portion18that bounds a main fluid flow lumen20disposed therein and between the opposed open ends14,16. The graft wall portion18may be made from any biocompatible, durable material, including, for example, PTFE, Dacron, and the like. Unless otherwise specifically stated, the term “PTFE” as used herein includes PTFE, porous PTFE and ePTFE, any of which may be impermeable, semi-permeable, or permeable. Furthermore, the graft assembly10and any portions thereof including the main body and extensions described herein may include all PTFE, all ePTFE, or a combination thereof. In one particular embodiment, the graft wall portion18includes a porous PTFE material having no discernable node and fibril structure. Methods of formation of such materials include those methods described in U.S. Pat. No. 8,728,372 to Humphrey et al, entitled “PTFE Layers and Methods of Manufacturing”, which is incorporated by reference in its entirety herein.

With regard to graft embodiments discussed herein, such as graft assembly10, and components thereof, the term “proximal” refers to a location towards a patient's heart and the term “distal” refers to a location away from the patient's heart. With regard to delivery system catheters and components thereof discussed herein, the term “distal” refers to a location that is disposed away from an operator who is using the catheter and the term “proximal” refers to a location towards the operator.

The graft assembly10may include a proximal anchor member22, which may be disposed at a proximal end14of the main graft12, in particular at a neck portion13which is free of inflatable channels28. One representative anchor system may include one as depicted inFIG.3. The anchor member22includes a proximal stent24, which may be self-expanding or may be balloon-expandable, that is formed from an elongate element having a generally serpentine shape with a number of crowns or apices at either end. As depicted inFIG.2, six crowns or apices are shown for stent24. The number of crowns or apices is not limiting and any suitable number may be used. As depicted inFIG.3, eight crowns or apices may be used. Further, while the stent24is depicted as a single stage stent, the present invention is not so limited. Stent24may include two or more stages of interconnected stent portions. The number of crown in one stage may be the same or different from the number of crowns in another stage.

A distal end of the stent24may be mechanically coupled to a connector ring26which is embedded in graft material at the proximal end14of the main graft12, or directly coupled to perforations in the proximal edge region of the main graft. Embodiments of the connector ring26may be generally circular in shape have regular undulations about the circumference that may be substantially sinusoidal in shape. U.S. Pat. No. 7,147,660, which is incorporated by reference herein, also includes anchor member embodiments that may be used for embodiments discussed herein.

The graft assembly10is not limited to the use of connector rings for securing anchor members to the graft portions of the graft assembly10. Other securing techniques and securing members, such as those disclosed in U.S. Patent Application Publication No. 2013/0268056 to Chobotov et al., entitled “Low Profile Stent Graft and Delivery System”; and U.S. Patent Application Publication No. 2013/0268057 to Vinluan et al., entitled “Low Profile Stent Graft and Delivery System”; the entirety of each of which is incorporated herein by reference, may suitably be used.

Anchor member22may be configured as a self-expanding anchor member having an undulating pattern and may be made from stainless steel, nickel titanium alloy (NiTi), such as NITINOL, or any other suitable material. The anchor member22may be configured to be balloon expandable or self-expanding in an outward radial direction from a radially compressed state. The proximal anchor member22and its components may have the same or similar features, dimensions or materials to those of the stents described in U.S. Pat. No. 7,147,660 to Chobotov et al., entitled “Advanced Endovascular Graft”, the content of which is hereby incorporated by reference in its entirety.

A network of inflatable elements or channels (generally depicted as reference numeral28inFIG.1) is disposed on the graft body12. The graft assembly10may include at least one proximal circumferential inflatable channel28A and at least one distal circumferential inflatable channel28B. The inflatable channels28may extend around the entire circumference of the graft body12or may only extend partially around the circumference of the graft body12. The at least one proximal circumferential inflatable channel28A and the at least one distal circumferential inflatable channel28B may be in communication, for example fluid communication, with each other via a longitudinal inflatable fill channel30. The longitudinal inflatable fill channel30is a tubular structure which is designed to allow communication between the interior of the inflatable channels28A,28B. The inflatable channels28A,28B may be inflated under pressure with an inflation material (not shown) through a longitudinal inflatable fill channel30that has a lumen disposed therein in fluid communication with the network of inflatable channels28. The inflation material may be retained within the network of inflatable channels28by a one way-valve (not shown), disposed within the lumen of the longitudinal inflatable fill channel30. The network of inflatable channels28may optionally be filled with a hardenable material that may be configured to harden, cure or otherwise increase in viscosity or become more rigid after being injected into the channels. Hardenable inflation materials such as gels, liquids or other flowable materials that are curable to a more solid or substantially hardened state may be used to provide mechanical support to the graft body12by virtue of the mechanical properties of the hardened material disposed within the channels28. The network of inflatable channels28may also provide structural support to the graft body12when in an inflated state due to the stiffness of the channels created by the increased interior pressure within the channels even if a non-hardenable inflation material, such as saline or the like, is used so long as an increased interior pressure can be maintained. Such an increase in stiffness or rigidity may be useful for a variety of purposes. For example, during deployment, inflation of the network of inflatable channels28may urge the graft body12including the main flow channel and legs thereof to conform to a generally cylindrical configuration having open flow lumens which may be useful when attempting to locate and navigate the flow lumens of the graft assembly10with a delivery catheter, guidewire or the like. Such location and navigation of the flow lumens of the graft assembly10and portions thereof may also be facilitated by the use of radiopaque inflation materials that provide enhanced visualization under fluoroscopic imaging.

The network of inflatable channels28may include one or more circumferential channels disposed completely or partially about the graft body12as well as longitudinal or helical channels that may provide support as well as a conduit in communication with the circumferential channels28that may be used for filling the network of inflatable channels28with inflation material. Some embodiments may also employ radiopaque inflation material to facilitate monitoring of the fill process and subsequent engagement of graft extensions (when used). The network of inflatable channels28may also include one or more one or more enlarged circumferential channels in the form of inflatable cuffs. The inflatable cuff (or cuffs) is disposed towards the end of the graft body12, such as at the proximal end14or distal end16. One example of a proximal inflatable cuff is depicted inFIG.2as the circumferential inflatable channel28A. An inflatable cuff or cuffs disposed at the ends of the body12may be configured to seal to an inside surface of a patient's vessel such as a patient's abdominal aorta. An inflatable cuff may be disposed on a portion of the main graft12distal of the proximal anchor member22A and has an outer surface that extends radially from a nominal outer surface of the main graft12. The inflatable cuff may be configured to expand radially beyond a nominal outer surface of the main graft12and provide a seal against an inside surface of a body lumen when the inflatable cuff is inflated with an inflation material to an expanded state. The axial separation of the proximal anchor member22and proximal inflatable cuff28A allows for spatial separation of the primary anchoring mechanism and at least part of the sealing function which may allow the graft to be restrained or otherwise compressed to a smaller outer profile for deployment from a delivery catheter. An interior cavity of any inflatable channels28(including one or more inflatable cuffs) is in fluid communication with the interior cavity of the remaining network of inflatable channels28and may have a transverse dimension or inner diameter of about 0.040 inches to about 0.250 inches.

Some embodiments of main graft member12may include about 1 to about 8 circumferential inflatable channels disposed about the graft body12. Some embodiments of the graft body12may include about 1 to about 4 longitudinal (or axial) inflatable fill channels30that may serve to connect the circumferential inflatable channels28. Some embodiments of the circumferential channels28may extend a full circumference of the graft section upon which they are disposed, or they may extend only partially around the graft section upon which they are disposed. For the graft body embodiment 12 shown inFIGS.1and2, the network of inflatable channels28includes an inflatable cuff (28A) disposed adjacent the proximal end14of the main body portion of the graft body12. A longitudinal or axial channel extends substantially along the graft body12in fluid communication with the circumferential channels28and proximal inflatable cuff28A at the proximal end of the graft body12. The longitudinal inflatable channel30extends between and is in fluid communication with three of the distal inflatable channels28B. As the inflation material is disposed through the longitudinal fill channel30, each of the inflatable channels28(including proximal inflatable cuff28A and distal inflatable channels28B) are filled with inflation material. In addition, the longitudinal inflatable channel30is filled with inflation material, resulting in a rigid and strong graft assembly10.

Some of the inflatable channels28of the graft assembly10discussed herein may be disposed circumferentially and axially. Alternatively, such inflatable channels28may be disposed in spiral, helical, or other configurations. Examples of channel configurations suitable for embodiments of the present invention are described further in U.S. Pat. No. 7,150,758 to Kari et al., entitled “Kink Resistant Endovascular Graft”, the entirety of which is incorporated herein by reference. All inflatable channel embodiments described herein as circumferential, may alternatively take on any of the aforementioned alternative configurations. Other modular graft embodiments are discussed in U.S. Patent Application Publication No. 2006/0224232 to Chobotov, entitled “Hybrid Modular Endovascular Graft”, which is hereby incorporated by reference herein in its entirety.

The network of inflatable channels28, including an inflatable cuff and longitudinal inflatable channel30, may be filled during deployment of the graft with any suitable inflation material. As discussed above, the inflation material may be used to provide outward pressure or a rigid structure from within the network of inflatable channels28. Biocompatible gases, liquids, gels or the like may be used, including curable polymeric materials or gels, such as the polymeric biomaterials described in U.S. Pat. No. 7,744,912 and entitled “Biomaterials Formed by Nucleophilic Addition Reaction to Conjugated Unsaturated Groups” to Hubbell et al.; U.S. Pat. No. 6,958,212 and entitled “Conjugate Addition Reactions for Controlled Delivery of Pharmaceutically Active Compounds” to Hubbell et al.; and further discussed in U.S. Pat. No. 7,147,660 and entitled “Advanced Endovascular Graft” to Chobotov, et al., each of which is incorporated by reference herein in its entirety. Some embodiments may use inflation materials formed from glycidyl ether and amine materials, as discussed in U.S. Patent Application Publication No. 2006/0222596 and entitled “Non-Degradable, Low-Swelling, Water Soluble Radiopaque Hydrogel Polymer” to Askari et al., the contents of which are incorporated herein by reference. Some inflation material embodiments may include an in situ formed hydrogel polymer having a first amount of diamine and a second amount of polyglycidyl ether wherein each of the amounts are present in a mammal or in a medical device, such as an inflatable graft, located in a mammal in an amount to produce an in situ formed hydrogel polymer that is biocompatible and has a cure time after mixing of about 10 seconds to about 30 minutes and wherein the volume of said hydrogel polymer swells less than 30 percent after curing and hydration. Some embodiments of the inflation material may include radiopaque material such as sodium iodide, potassium iodide, barium sulfate, Visipaque 320, Hypaque, Omnipaque 350, Hexabrix and the like. For some inflation material embodiments, the polyglycidyl ether may be selected from trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, polyethylene glycol diglycidyl ether, resorcinol diglycidyl ether, glycidyl ester ether of p-hydroxy benzoic acid, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A (PO)2diglycidyl ether, hydroquinone diglycidyl ether, bisphenol S diglycidyl ether, terephthalic acid diglycidyl ester, and mixtures thereof. For some inflation material embodiments, the diamine may be selected from (poly)alkylene glycol having amino or alkylamino termini selected from the group consisting of polyethylene glycol (400) diamine, di-(3-aminopropyl) diethylene glycol, polyoxypropylenediamine, polyetherdiamine, polyoxyethylenediamine, triethyleneglycol diamine and mixtures thereof. For some embodiments, the diamine may be hydrophilic and the polyglycidyl ether may be hydrophilic prior to curing. For some embodiments, the diamine may be hydrophilic and the polyglycidyl ether is hydrophobic prior to curing. For some embodiments, the diamine may be hydrophobic and the polyglycidyl ether may be hydrophilic prior to curing.

Other inflation materials that may be used for some embodiments include polyethylene oxide materials and neopentyl glycol diacrylate materials which are discussed in U.S. Pat. No. 6,610,035 to Yang et al., entitled “Hydrophilic Lubricity Coating for Medical Devices Comprising a Hybrid Top Coat”, and U.S. Pat. No. 6,176,849 to Yang et al., entitled “Hydrophilic Lubricity Coating for Medical Devices Comprising a Hybrid Top Coat”; which are incorporated by reference herein in their entirety. U.S. Pat. No. 7,147,660 to Chobotov et al., entitled “Advanced Endovascular Graft”, the contents of which are incorporated herein by reference, also includes inflation material embodiments that may be used for embodiments discussed herein.

FIGS.4A and4Bshow a bifurcated modular tandem embodiment of a graft assembly110for treatment of an abdominal aortic aneurysm400. The tandem graft assembly110includes the main graft assembly10, a first modular branched leg or stent-graft extension118(having a first leg lumen119) and a second modular branched leg or stent-graft extension120(having a second leg lumen121). In some embodiments, the first branched leg118may be referred to as an “ipsilateral leg”118, and the second branched leg120may be referred to as a “contralateral leg”120.

The first and second graft legs118and120may be formed from an inner layer or layers and outer layer or layers of flexible graft material, such as PTFE or ePTFE. In one embodiment, the flexible graft material includes PTFE which is substantially porous but includes no discernable node and fibril structure. The inner and outer layers of graft material may be formed from tubular extrusions, laminated wraps of multiple layers of graft material or materials, and the like. The inner or outer layers of graft material may be permeable, semi-permeable or substantially non-permeable for some embodiments. For some embodiments, the nominal length of the legs118and120may be permeable with one or more longitudinal sections, such as a middle longitudinal section, being semi-permeable or non-permeable. Some embodiments of the graft legs118and120may have an overall tapered or flared configuration with a nominal inner lumen that tapers or flares when the graft extension is in a relaxed expanded state. For embodiments that include laminated wraps of material, the wraps may be carried out circumferentially, helically or in any other suitable configuration.

The first and second leg118and120are desirably stent-graft devices. A first radially expandable stent300may be interposed between an outer layer (not shown) and inner layer (not shown) of graft material for these legs. The interposed stent disposed between the outer layer and inner layer of graft material may be formed from an elongate resilient element helically wound with a plurality of longitudinally spaced turns into an open tubular configuration. The helically wound stent may be configured to be a self-expanding stent or radially expandable in an inelastic manner actuated by an outward radial force from a device such as an expandable balloon or the like. Some tubular prosthesis embodiments that may be used for graft extensions118and120are discussed in U.S. Pat. No. 6,673,103 to Golds et al., entitled “Mesh and Stent for Increased Flexibility”, which is hereby incorporated by reference in its entirety herein.

Further details of the legs118and120as shown in more detail inFIGS.5,6,7,8A-8E,9A,9B and10. As can be seen, a generally tubular stent300may be provided. The tubular stent300includes a helically-wound, undulating wire forming a series of adjacent helical windings302, which may be made from the materials described above (including a resilient metal such as nitinol). The ends304,306of the stent300may be secured to adjacent ring portions of the stent at distinct areas. For example, a first end may be adjoined via a first securement point308, and a second end may be joined at a second securement point310, as shown to avoid exposure of element ends to either PTFE graft material or possible patient tissues. In a preferred embodiment, the securement points308,310are located proximal to the first end304and second end306, respectively, with no other securement points on the stent300. That is, aside from the helical windings302at the first end304(which may be referred to as a proximal end304) and second end306(which may be referred to as a distal end306), respectively, adjacent approximate circumferential windings302in the stent300may be free of interconnecting securement points. Any securement means may be used, including, for example, welding, such as struts and welds. It is desired that the relative stiffness of a stent be greater than the stiffness of the PTFE graft material so as to provide beneficial kink resistance.

The undulating wire may be a continuous element forming a series of helical windings302extending from one end304of the extension to the other end306thereof. The tubular stent300thus has an internal lumen320extending there through, from the first end304to the second end306. The ends304,306of the elongate element may be secured to adjacent ring members by any suitable means such as adhesive bonding, welding such as laser welding, soldering or the like. For some embodiments, the stent element may have a transverse dimension or diameter of about 0.005 inch to about 0.015 inch. As may be seen inFIGS.6and7, the stent300may be tapered or flared. In addition, if desired, adjacent helical windings302may be arranged315such that adjacent helical windings302at one end (either the first end304or second end306) have an acute angle formation at a portion of the stent300proximal to the end of the stent300. That is, if desired, the helical winding closest to the end (shown as302′) may have an approximately 180° angle with respect to the longitudinal axis, while the helical winding next to this helical winding (shown as302″) has an angle less than 180°. These two helical windings (302′ and302″) may be attached at securement points308,310.

FIGS.8A through8Edepicts various arrangements of the helical windings302formed by the undulating wire in forming the stent300. Adjacent helical windings are depicted as302A and302B, but it will be understood that the arrangement depicted inFIGS.8A through8Emay be applied to each helical winding302in the stent300. Alternatively, the arrangements depicted inFIGS.8A through8Emay be applied to only some of the helical windings302in the stent300. Undulating wire of the stent300includes a series of peaks312and valleys314as the wire is helically wound. The arrangement of peaks312and valleys314may vary and may be arranged in any fashion desired. In some embodiments, such as that ofFIG.8A, the peaks312of one circumferential winding302A may be substantially aligned with the peaks312of an adjacent circumferential winding302B. As can be seen inFIG.8B, the adjacent circumferential windings302A and302B may be spaced apart. As can be seen inFIG.8C, the adjacent circumferential windings302A and302B may be closer together. In another embodiment, set forth inFIG.8D, one peak312of one circumferential winding302B may span two peaks312of an adjacent winding302A. In another embodiment set forth inFIG.8E, the peaks312of one circumferential winding302A may be substantially aligned with the valleys314of an adjacent circumferential winding302B. Other arrangements for the helical windings302are contemplated and will be readily understood by those of skill in the art.

The distances between adjacent windings302A,302B may vary along the length of the stent300, where the distance at one end304is different than the distance at the second end306. In each embodiment, there are two distances that should be considered. The first distance X is the distance between the lowest valley (314) of the first winding (302A) and the highest peak (312) of the second winding (302B). The second distance Y is the distance between the highest peak (312) and lowest valley (314) of the first winding (302A).

There may be at least two different ratios of X/Y (or equivalently X/Y) present in the device, including but limited to three different relative ratios of these distances X/Y. The first ratio is where X/Y is a relatively large positive number, that is, there is a relatively larger separation between the distance (X) as compared to the distance (Y). The second ratio is where X/Y is a relatively smaller positive number, that is, there is a relatively smaller separation between the distance (X) as compared to the distance (Y). Finally, the third ratio is where X/Y is a negative number, that is, the lowest peak of the first winding (302A) dips to a point lower than the highest peak of the second winding (302B). An example of a negative ratio is seen inFIG.10C, where a negative value for X can be seen.

The ratio X/Y can be manipulated to obtain the desired properties of the stent graft in a local region. A relatively large X/Y ratio (preferably greater than about 0.5) produces a highly flexible region of a stent graft. A smaller X/Y ratio (preferably from about 0.1 to about 0.5) produces regions of a stent graft with moderate flexibility and moderate radial force. A region of a stent graft with an even smaller or negative X/Y ratio (preferably less than about 0.1) has a relatively high radial force with relatively less flexibility. The above ranges for X/Y are appropriate when the stent height Y is from about one-third of the diameter of the stent to about equal to the diameter of the stent. If Y is larger than this when compared to D, then the ranges for the X/Y ratios quoted above will be reduced. Similarly, if Y is much smaller than the stent diameter D, then the numerical values for the ranges above will be increased.

Using the principle described above, a stent graft can be constructed with varying ratios of X/Y along the length to achieve desired properties. For example, if a stent graft is used as an iliac limb in a modular endovascular graft for abdominal aortic aneurysms (AAAs), it may be desirable for the proximal end of the stent graft to have a relatively high radial force to maximize anchorage into the aortic body component of the modular system. In this case, the proximal end of the iliac limb could be designed with a small or negative X/Y ratio, such as −0.5, and Y may be chosen to be, for example, from about one fifth to one half of the stent graft diameter. In this region flexibility is less important than radial force so the negative X/Y ratio yields the desired properties. In the middle of the stent graft flexibility becomes important to accommodate the tortuous common iliac arteries often found in AAA patients. It may then be desirable to have a relatively large X/Y ratio, such as about 0.55, to achieve this flexibility. Near the distal end of the stent graft it may again be desirable to have more radial force to promote anchorage and sealing of the iliac limb into the common iliac artery of the patient, but not as much radial force as at the proximal end. In this case, it may be desirable to have an X/Y ratio near zero, or from about −0.1 to about 0.3.

Since the stent is formed in a helix along the length of the stent graft, it is possible to continuously vary the X/Y ratio to achieve the desired properties in various regions of the stent graft with smooth variations and no abrupt changes along the length. These smooth variations promote conformance to the vasculature and avoid the stress and/or strain concentrations and potential kinking that can result from abrupt transitions in mechanical properties along the length of a stent graft.

The stent300may include a longitudinal axis (generally defined along internal lumen320) and a radial axis perpendicular to the longitudinal axis; where the helical windings302are wound at an acute winding angle of about 3 degrees to about 15 degrees with respect to the radial axis. As can be seen inFIGS.6and7, the acute winding angle at a portion of the stent300proximal to the first end304is different from the acute winding angle at a portion of the stent300proximal to the second end306. In some embodiments, a first helical winding302at the first end304may be perpendicular to the longitudinal axis. Further, it may be desired that a helical winding302at the second end306is perpendicular to the longitudinal axis. Helical windings302at the first end304and the second end306may both be perpendicular to the longitudinal axis, or only one may be perpendicular to the longitudinal axis. An adjacent peak312and an adjacent valley314of a helical winding302have a peak height from an apex of said adjacent peak to a base of said adjacent valley. It may be desired that the peak height at a portion of the stent300proximal to the first end304of the stent300is different from the peak height at a portion of the stent300proximal to the second end306of the stent300.

At least one graft layer may be disposed on the stent300. The placement of the graft layers may best be seen inFIGS.9A,9B and10. In some embodiments, an inner graft layer318may be disposed on the interior surface of the helically wound stent300, forming inner lumen320. A second graft layer316may be disposed on the outer surface of the helically wound stent300, forming an outside surface. More than one or two layers of graft material may be disposed on the interior or exterior of the helically wound stent300as desired. For some embodiments of first or second graft extensions142,144, layers of materials having different properties may be used in combination to achieve a desired clinical performance. For example, some layers of PTFE covering the stent300may be permeable, semi-permeable or substantially non-permeable depending on the desired performance and material properties. The layers316and318may be applied by a variety of methods and have a variety of configurations. For example, some layer embodiments may include extruded tubular structures applied axially over a mandrel or subassembly. Some layer embodiments 316 and 318 may be applied by wrapping layers circumferentially or wrapping tapes or ribbons in an overlapping helical pattern. For some embodiments, the outer layer316may be made from or include a semi-permeable or substantially non-permeable PTFE layer and the inner layer318may be made of or include a permeable layer of PTFE.

The first and/or second graft extensions142,144may be made by forming the layers of material316,318together with the helically wound stent300over a mandrel, such as a cylindrical mandrel (not shown). Once the innermost layer316of the extension142,144has been wrapped about a shaped mandrel, a helical nitinol stent, such as helical stent300, may be placed over the innermost layered PTFE layer316and underlying mandrel. If desired, one or more additional layers318of graft material may be wrapped or otherwise added over the exterior of the stent300. If desired, the outer layer318may include low permeability PTFE film or PTFE film having substantially no permeability that does not have the traditional node fibril microstructure. The mandrel may then be covered with a flexible tube such that the layers316,318and stent300are sandwiched under pressure and sintered so as to raise the temperature for the PTFE material to undergo a melt transformation in order to lock in its geometry and strength. The flexible tube (a manufacturing aid not shown) is removed from over the device and the resultant graft extension (142,144) is removed from the mandrel.

The main graft10and graft portions of the first and second graft legs118and120may be made at least partially from polytetrafluoroethylene (PTFE) which may include expanded polytetrafluoroethylene (ePTFE). In particular, main graft10and graft legs118and120may include any number of layers of PTFE and/or ePTFE, including from about 2 to about 15 layers, having an uncompressed layered thickness of about 0.003 inches to about 0.015 inches for the supple graft material or materials alone without supporting or ancillary structures such as high strength stents, connector rings or the like. Such graft body sections may also include any alternative high strength, supple biocompatible materials, such as DACRON, suitable for graft applications. Descriptions of various constructions of graft body sections as well as other components of graft assembly110that may be used in any suitable combination for any of the embodiments discussed herein may be found in U.S. Pat. No. 7,125,464 to Chobotov et al., entitled “Method and Apparatus for Manufacturing an Endovascular Graft Section”; U.S. Pat. No. 7,090,693 to Chobotov et al., entitled “Endovascular Graft Joint and Method of Manufacture”; U.S. Pat. No. 7,147,661, entitled “Method and Apparatus for Shape Forming Endovascular Graft Material”, to Chobotov et al.; U.S. Pat. No. 7,147,660 to by Chobotov et al., entitled “Advanced Endovascular Graft”; and U.S. Pat. No. 8,728,372 to Humphrey et al., entitled “PTFE Layers and Methods of Manufacturing”; the entirety of each of which is incorporated herein by reference.

Additional details of the above-described graft assemblies, including modular components, may be found in U.S. Patent Application Publication No. 2013/0261734 to Young et al., entitled “Advanced Kink Resistant Stent Graft”; the entirety of which is incorporated herein by reference.

Returning toFIGS.4A,4B,11A,11B and11C, the tandem modular graft assembly offers advantages over systems of the prior art. For example, modular endografts typically employ a bifurcated main body section with separate lumens configured to receive one or more separate stent grafts to connect the main body section to distal branch arteries. The Ovation Abdominal Stent Graft System is an example of a tri-modular AAA system which employs a bifurcated main body section and two iliac limb stent grafts to bridge the main body to the iliac arteries. An alternative to this approach is to use a tubular main body section which can receive two or more stent grafts to bridge to various distal branch vessels. Using highly conformable stent grafts for these extension components can allow deploying two or more in the single open end of the main body. This allows for simplified manufacturing of the main body (avoiding the need to form a bifurcated structure), and also simplifies access or cannulation of the main body during deployment in the patient since a single large lumen is accessed as opposed to a smaller contralateral branch typically employed in modular AAA stent graft systems. The two limbs can be deployed simultaneously to ensure balanced “sharing” of the lumen by the stent grafts. Subsequent ballooning (“kissing balloons”) can be employed to further balance the lumens and reduce the possibility for endoleaks at the junction (“type 3 endoleaks”). The main body can be constructed with inflatable annular rings along its length, and may also optionally include wire support elements. Making the mid part of the aortic body a little larger than its distal opening can further avoid the possibility of “limb steal” since the proximal ends of the limbs would be in a diameter large enough for both of their proximal ends to more fully expand, even if the two limbs are not deployed at exactly the same elevation (one more proximal than the other). Specifically for Ovation, making the aortic body with its distal end section about 17-18 mm in diameter (and constant at this diameter for a length of about 3-4 cm), two iliac limbs with 14 mm proximal ends would engage with adequate oversizing. Cannulation is greatly facilitated since the single large target lumen would be over 3 times larger in area than Ovation's contralateral gate currently sized at 9-11 mm. Furthermore, since there is only one large stable opening to access during cannulation, inadvertent access to the ipsilateral gate is not possible in this new single lumen configuration. No tether as employed by the Ovation system would be needed for contralateral leg stabilization (since there isn't a contra leg), so this would be a simplification of the delivery catheter. Additionally, there would be no need for rotational markers on the delivery system since the tubular aortic body can be made axisymmetric. Another benefit of this approach is that the device can be used as an AUI (aorto-uni iliac) device, ideal for ruptures or anatomy with severely diseased arteries on either iliac side.

Various methods of delivery systems and delivery of the device into a patient include those described in U.S. Patent Application Publication No. 2009/0099649 to Chobotov et al., entitled “Modular Vascular Graft for Low Profile Percutaneous Delivery”, the contents of which are incorporated by reference in entirety herein. For endovascular methods, access to a patient's vasculature may be achieved by performing an arteriotomy or cut down to the patient's femoral artery or by other common techniques, such as the percutaneous Seldinger technique. For such techniques, a delivery sheath (not shown) may be placed in communication with the interior of the patient's vessel such as the femoral artery with the use of a dilator and guidewire assembly. Once the delivery sheath is positioned, access to the patient's vasculature may be achieved through the delivery sheath which may optionally be sealed by a hemostasis valve or other suitable mechanism. For some procedures, it may be necessary to obtain access via a delivery sheath or other suitable means to both femoral arteries of a patient with the delivery sheaths directed upstream towards the patient's aorta. In some applications a delivery sheath may not be needed and a delivery catheter may be directly inserted into the patient's access vessel by either arteriotomy or percutaneous puncture.

FIG.11Adepicts the initial placement of the modular endovascular graft assembly110of the present invention within a patient's vasculature. The modular endovascular graft assembly110may be advanced along a first guidewire (not shown) proximally upstream of blood flow into the vasculature of the patient including iliac arteries402,404and aorta406shown inFIG.11A. While the iliac arties402,404may be medically described as the right and left common iliac arteries, respectively, as used herein iliac artery402is described as an ipsilateral iliac artery and iliac artery404is described as a contralateral iliac artery. The flow of the patient's blood (not shown) is in a general downward direction inFIG.11A. Other vessels of the patient's vasculature shown inFIG.11Ainclude the renal arteries408and hypogastric arteries410.

The modular endovascular graft assembly110may be advanced into the aorta406of the patient until the endovascular prosthesis10is disposed substantially adjacent an aortic aneurysm400or other vascular defect to be treated. The portion of the endovascular delivery system that is advanced through bodily lumens is a low profile delivery system; for example, having an overall outer diameter of less than 14 French. Other diameters are also useful, such as but not limited to less than 12 French, less than 10 French, or any sizes from 10 to 14 French or greater.

The proximal anchor member22is positioned across the renal arteries408to maintain blood there through. The anchor member22serves to anchor the graft assembly within the aorta406. The proximal circumferential inflatable channel28A of the main graft body10is placed beyond the aneurysm400in the aorta406. Upon inflation of the proximal circumferential inflatable channel28A, this inflated channel seals blood flow, if desired, from the aneurysm400. As depicted inFIGS.11A,11B and11C, after the main graft body10and anchor member22are deployed, the modular graft extension legs118,120are deployed. The modular graft extension leg118is deployed through the iliac artery402via catheter420, and the modular graft extension leg120is deployed through the iliac artery404via catheter422. The modular graft extension legs118,120may be deployed in separate stages or substantially and/or approximately in a simultaneous manner. The proximal ends304of the modular graft extension legs118,120are disposed within the distal end portion16of the graft body12. Upon expansion of the stents300within the modular graft extension legs118,120and upon inflation of the distal inflatable channels28B, the modular graft extension legs118,120conform to the shape of the graft10in vivo to provide a modular assembly. The distal ends306of the modular graft extension legs118,120are deployed within the respective iliac arteries402,404, as depicted inFIG.11C.

The following embodiments or aspects of the invention may be combined in any fashion and combination and be within the scope of the present invention, as follows:

Embodiment 1. A modular endovascular graft assembly (110) comprising:a main elongate tubular graft body (10,12) having a proximal open (14) end and an opposed distal open end (16), defining a graft body wall (18) having a proximal portion, a medial portion, a distal portion and an open lumen (20) therein between;the graft body wall (18) comprising a proximal neck portion (13) disposed at the proximal end (14);the graft body wall (18) comprising at least one circumferential inflatable channel (28A) disposed towards the proximal portion of the graft body wall (18) near the proximal open end (14) of the main tubular graft body (10,12) and distally prior the proximal neck portion (13);the graft body wall (18) comprising a plurality of circumferential inflatable channels (28B) disposed towards the distal portion of the graft body wall (18) near the distal open end (16) of the main tubular graft body (10,12);a proximal expansion anchor (22) disposed at or secured to the proximal neck portion (13) of the graft body wall (18);a first and second elongate tubular stent-graft extensions (118,120,300) percutaneously disposed into the distal end (16) of the tubular graft body (10,12), the first and second stent-graft extensions (118,120,300) having respective proximal open ends (304) and opposed distal open ends (306), defining graft body walls having a proximal portions, medial portions, distal portions and open lumens (119,121,320) therein between;wherein, in combination, the proximal portions of the first and second stent-graft extensions (118,120,300) are conformable to a shape of the open lumen (20) of the main graft body (10,12).

Embodiment 2. The assembly (110) of embodiment 1, wherein the at least one circumferential inflatable channel (28A) disposed towards the proximal portion of the graft body (10,12) and the plurality of circumferential inflatable channels (28B) disposed towards the distal portion of the graft body (10,12) are in fluid communication with one and the other.

Embodiment 3. The assembly (110) of any of the preceding embodiments, further comprising an inflation material for inflating the at least one circumferential inflatable channel (28A) disposed towards the proximal portion of the graft body (10,12) and the plurality of circumferential inflatable channels (28B) disposed towards the distal portion of the graft body (10,12).

Embodiment 4. The assembly (110) of embodiment 3, wherein the inflation material is an in vivo curable material.

Embodiment 5. The assembly (110) of any of the preceding embodiments, wherein the first and second elongate tubular stent-graft extensions (118,120) comprise a tubular stent (300) securably disposed between a graft liner (318) and a graft cover (316); the stent (300) comprising an undulating wire having opposed first and second ends and being helically wound into a plurality of approximate circumferential windings (302) to define a stent wall; the undulating wire having a plurality undulations defined by peaks and valleys with peaks of adjacent approximate circumferential windings being separated by a distance.

Embodiment 6. The assembly (110) of embodiment 5, wherein the graft liner (318) comprises at least one layer of porous PTFE having no discernable node and fibril structure.

Embodiment 7. The assembly (110) of embodiment 5, wherein; the graft covering (316) comprises at least one layer of porous PTFE having no discernable node and fibril structure.

Embodiment 8. The assembly (110) of any of the preceding embodiments, wherein the graft body wall (18) of the main tubular graft (10,12) comprises at least one layer of porous PTFE having no discernable node and fibril structure.

Embodiment 9. The assembly (110) of any of the preceding embodiments, wherein, in combination, the proximal portions of the first and second stent-graft extensions (118,120) are conformable to the shape of the open lumen (20) of the main graft body (10,12) to prevent flow of bodily fluid between outer proximal portions of the first and second stent-graft extensions (118,120) and the open lumen (20) of the main tubular graft (10,12).

Embodiment 10. The assembly (110) of any of the preceding embodiments,wherein the open lumen (20) of the main tubular graft (10,12) has approximately or substantially circular cross-section;wherein the open lumens (119,121) of the proximal portions of the first and second stent-graft extensions have approximately or substantially circular cross-sections prior to being percutaneously disposed into the distal end (16) of the tubular graft body (10,12); andwherein the open lumens (119,121) of the proximal portions of the first and second stent-graft extensions (118,120), in combination, have non-circular-shaped cross-sections after being percutaneously disposed into the distal end (16) of the tubular graft body (10,12).

Embodiment 11. The assembly (110) of any of the preceding embodiments,wherein the open lumen (20) of the main tubular graft (10,12) has approximately or substantially circular cross-section;wherein the open lumens (119,121) of the proximal portions of the first and second stent-graft extensions (118,120) have approximately or substantially circular cross-sections prior to being percutaneously disposed into the distal end (16) of the tubular graft body (10,12); andwherein the open lumens (119,121) of the proximal portions of the first and second stent-graft extensions (118,120) have approximately or substantially D-shaped cross-sections after being percutaneously disposed into the distal end (16) of the tubular graft body (118,120).

Embodiment 12. The assembly (110) of any of the preceding embodiments, wherein the proximal expansion anchor (22) is a metallic member.

Embodiment 13. The assembly (110) of embodiment 12, wherein the metallic member comprises a super elastic nitinol (NiTi) alloy.

Embodiment 14. The assembly (110) of any of the preceding embodiments, wherein the proximal expansion anchor (22) is a dual stage member where a first crown portion having a first number of crowns and a second crown portion having a second number of crowns, where the first number of crowns may be the same as or different from the second number of crowns.

Embodiment 15. A method of delivering a modular endovascular graft assembly (110), comprising:providing the modular endovascular graft assembly (110) of embodiment 1;percutaneously delivering the main elongate tubular graft body (10,12) and the proximal expansion anchor (22) into a main bodily lumen (406) having an aneurysm (400) and having a first and second lumen branches (402,404);positioning the proximal expansion anchor (22) and the at least one circumferential inflatable channel (28A) of the main graft body (10,12) distally past the aneurysm (400);percutaneously delivering the first elongate tubular stent-graft extension (118) into the distal end (16) of the tubular graft body (10,12); andpercutaneously delivering the second elongate tubular stent-graft extension (120) into the distal end (16) of the tubular graft body (10,12).

Embodiment 16. The method of embodiment 15, further comprising:expanding the proximal expansion anchor (22) to secure the proximal expansion anchor (22) to the bodily lumen (406).

Embodiment 17. The method of any of the embodiments 15 to 16, further comprising:inflating the at least one circumferential inflatable channel (28A) of the main graft body (10,12) with an inflation material to seal the main graft body (10,12) against the bodily lumen (406).

Embodiment 18. The method of any of the embodiments 15 to 17, further comprising:curing the inflation material.

Embodiment 19. The method of any of the embodiments 15 to 18, wherein the percutaneously delivery of the first and second elongate tubular stent-graft extensions (118,120) are approximately simultaneous.

Embodiment 20. The method of any of the embodiments 15 to 19,wherein the distal portion of the first elongate tubular stent-graft extension (118) is disposed within the first lumen branch (402); andwherein the distal portion of the second elongate tubular stent-graft extension (120) is disposed within the second lumen branch (404).

While various embodiments of the present invention are specifically illustrated and/or described herein, it will be appreciated that modifications and variations of the present invention may be effected by those skilled in the art without departing from the spirit and intended scope of the invention. Further, any of the embodiments or aspects of the invention as described in the claims or in the specification may be used with one and another without limitation.