Stent grafts and methods of enhancing flexibility of stent grafts by thermal pleating

Abstract

To provide a graft layer to reestablish a flow lumen through an aneurysm, and a stent structure to support the graft.SOLUTION: A method for forming pleats 30a-e in a stent graft 1 includes forming pleats 30a-e in a graft material 10 of the stent graft 1 by compressing the stent graft 1, applying heat to the stent graft 1 to thermally set the pleats 30a-e in the graft material 10, and extending the stent graft 1 to uncompress the stent graft 1 after the pleats 30a-e are thermally set.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED PATENT APPLICATIONS] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62 / 532,737, filed July 14, 2017, which is incorporated herein by reference in its entirety.

[0002] One or more exemplary embodiments described herein relate generally to stent grafts and methods of making and using stent grafts, and in particular embodiments, to stent grafts and methods of making stent grafts that are flexible. [Background technology]

[0003] Aneurysms are enlargements or bulges in blood vessels that are often prone to rupture and therefore pose a serious risk to the patient. Aneurysms can occur in any blood vessel, but are of particular concern when they occur in the cerebral vasculature or aorta.

[0004] Abdominal aortic aneurysms (AAA) are classified based on their location within the aorta, as well as their shape and complexity. Aneurysms found below the renal arteries are called infrarenal abdominal aortic aneurysms. Suprarenal abdominal aortic aneurysms occur above the renal arteries. Thoracic aortic aneurysms (TAA) occur in the ascending, transverse, or descending portions of the upper aorta.

[0005] Stent grafts have become widely used for the treatment of aneurysms. Various stent grafts provide a graft layer that re-establishes a flow lumen through the aneurysm, as well as a stent structure that supports the graft. In general, endoluminal repair using a stent graft involves endoluminally accessing the aneurysm through either or both of the common iliac arteries. The stent graft is then implanted to treat the aneurysm. Summary of the Invention [Means for solving the problem]

[0006] One implementation of the present disclosure is a method of forming pleats in a stent graft, the method comprising the steps of forming pleats in the graft material of the stent graft by compressing the stent graft, applying heat to the stent graft to heat set the pleats in the graft material, and stretching the stent graft to decompress the stent graft after the pleats have been heat set.

[0007] In an embodiment, the step of applying heat may include ironing the pleat creases in the graft material.

[0008] In an embodiment, the iron may be heated to between 320°C and 390°C prior to the step of ironing the creases.

[0009] In an embodiment, compressing the stent graft may comprise axially and / or annularly compressing the stent graft.

[0010] In an embodiment, the step of applying heat may include baking the stent graft in an oven for a predetermined period of time after forming the pleats.

[0011] In an embodiment, the oven may be heated to 320° C. prior to baking the stent graft.

[0012] In an embodiment, the predetermined time may be five minutes.

[0013] In an embodiment, the predetermined period of time may be greater than five minutes.

[0014] In embodiments, forming the pleats may include folding the graft material over an adjacent portion of the graft material.

[0015] In embodiments, folding the graft material may include folding the graft material outwardly relative to the lumen of the stent graft.

[0016] In embodiments, folding the graft material may include folding the graft material intraluminally relative to the lumen of the stent graft.

[0017] In an embodiment, forming the pleats may include folding the graft material inwardly relative to the lumen of the stent-graft at a portion of the graft material and folding the graft material outwardly relative to the lumen of the stent-graft at a different portion of the graft material.

[0018] In an embodiment, forming the pleats may include folding the graft material over adjacent portions of the graft material so as to have a larger graft space between adjacent stent members on the more curvature side of the stent graft than on the less curvature side of the stent graft.

[0019] In an embodiment, the method may further comprise the step of increasing the graft space on the side of greater curvature to reduce the radius of curvature of the stent graft.

[0020] Another implementation of the present disclosure is a stent graft including a graft formed of graft material and a stent attached to the graft and including stent members, the graft material folded over adjacent portions of the graft members between the stent members to form pleats, the pleats having a larger graft space between corresponding stent members on a more curvature side of the stent graft than on a lesser curvature side of the stent graft.

[0021] Another implementation of the present disclosure is a stent graft manufactured by a process including the steps of forming pleats in the graft material of the stent graft by axially and / or annularly compressing the stent graft, applying heat to the stent graft to heat set the pleats in the graft material, and stretching the stent graft to decompress the stent graft after the pleats have been heat set.

[0022] In an embodiment, the step of applying heat may include ironing the pleat creases in the graft material.

[0023] In an embodiment, the step of applying heat may include baking the stent graft in an oven for a predetermined period of time after forming the pleats.

[0024] In embodiments, forming the pleats may include folding the graft material over an adjacent portion of the graft material.

[0025] In an embodiment, folding the graft material over adjacent portions of the graft material may include folding the graft material to have a larger graft space between adjacent stent members on a more curvature side of the stent graft than on a lesser curvature side of the stent graft. [Brief description of the drawings]

[0026] [Figure 1] FIG. 13 shows a stent graft according to an embodiment prior to heat setting of the pleats. [Figure 2A] 1 is a flow diagram of a method according to an embodiment. [Figure 2B] 2B illustrates a methodology that can be used in conjunction with the methodology of FIG. 2A according to various embodiments. [Figure 2C] 2B illustrates a methodology that can be used in conjunction with the methodology of FIG. 2A according to various embodiments. [Diagram 3]FIG. 1 shows a stent graft in an axially compressed state according to an embodiment. [Figure 4] FIG. 13 shows an iron being used on the graft material of a graft member of a stent graft according to an embodiment to heat set pleats to the graft material. [Diagram 5] FIG. 13 shows a stent graft according to an embodiment in a longitudinally stretched state after the pleats in the graft material have been heat set. [Figure 6] FIG. 2 shows a stent graft according to an embodiment in a bent configuration after pleats in the graft member have been heat set to form pleated sections in the stent graft. [Figure 7A] 13A-13C show a stent graft according to an embodiment having an outwardly luminally folded pleated section. [Figure 7B] FIG. 7B shows the inner surface of the graft member of the stent graft of FIG. 7A. [Figure 8A] FIG. 13 shows a stent graft according to an embodiment having an inwardly folded pleated section. [Figure 8B] FIG. 8B shows the inner surface of the graft member of the stent graft of FIG. 8A. [Figure 9A] FIG. 1 shows a stent graft according to an embodiment having a pleated section that is folded inwardly on the proximal end and outwardly on the distal end of the stent graft. [Figure 9B] FIG. 9B shows the inner surface of the graft member of the stent graft of FIG. 9A. [Figure 10] FIG. 1 shows two embodiments of a stent graft illustrating the effect of graft spacing between stent apices on the achievable radius of curvature. [Figure 11] FIG. 1 illustrates an embodiment of a stent graft in an annular compressed configuration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, like symbols typically identify similar items unless relatedness indicates otherwise. The exemplary embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the drawings, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are expressly contemplated and form a part of this disclosure.

[0028] Various embodiments provide for enhanced flexibility of the stent graft by thermally crimping the stent graft. Various embodiments provide for enhanced flexibility of an endovascular stent graft by (1) manually crimping the graft material, such as by axially compressing the stent graft to nest the shape of the stent graft in a preferred orientation, and (2) heat treating the stent graft while in the compressed position to provide a thermal memory to the graft material to preferentially fix the crimps and retain flexibility when the graft length is re-extended. Various embodiments allow for improved flexibility of the stent graft system for vascular applications by having heat set crimps in the graft material.

[0029] Various embodiments provide for heat setting of preferred pleat shapes in the graft material of a stent graft. Such heat set pleat shapes to the graft material can, for example, allow each apex formed by the stent members of a stent, having a zigzag pattern in the graft material, to consistently move relative to the zigzags of adjacent stent members without generating significant shear forces in the graft material, even when the stent members are fully fused or sintered into the graft material. In various embodiments, the heat set pleats substantially reduce or minimize irregularities in the contacting apexes, allowing the apexes to be uniformly tucked under or over adjacent apexes as desired.

[0030] Various methods according to various embodiments for heat setting the preferred pleat configuration are provided herein. One such method according to various embodiments includes the step of thermally ironing the pleats. In some such embodiments, the stent graft is first axially compressed to create the desired pleat pattern. In some embodiments, a soldering iron set at a temperature of, for example, 320° C. to 390° C. is then used to heat set the creases or pleats in the graft material by wiping the tip or barrel of the iron over the pleated areas between adjacent stent members. In various embodiments, other suitable temperatures can be used for the iron to iron the pleats. In various embodiments, once each of the creases or pleats is heat set in the desired area in the graft material, the stent graft can be axially pulled back (or stretched) to its natural or native length and will have improved (or significantly improved) flexibility over a non-pleated stent graft.

[0031] Another method according to various embodiments for heat setting the preferred pleat shape includes heat baking the pleats. In some such embodiments, the stent graft is first axially compressed to create the desired pleat pattern. Also in some such embodiments, one or more pleated portions of the stent graft are then placed in an oven set at a temperature of, for example, 320° C. or other suitable temperature for a desired or predetermined time to heat set the folds or pleats. In various embodiments, the bake time in the oven is, for example, 5 minutes, 10 minutes, and / or 20 minutes. However, the present disclosure is not limited thereto, and other suitable bake times can be used in other embodiments. In some embodiments, 5 minutes may be preferred as a short amount of time to substantially set the pleats. In various embodiments, the bake method may be advantageous in that it is a non-contact method of creating pleats. In various embodiments, once the folds or pleats are heat-set in the desired areas within the graft material, the stent graft can be axially pulled back (or stretched) to its natural or original length, resulting in improved (or significantly improved) flexibility over an unpleated stent graft.

[0032] Referring now to FIG. 1, a stent graft 1 according to an exemplary embodiment is shown. The stent graft 1 is a hollow tubular device having a graft member 10 forming a tubular wall having a proximal end 11 and a distal end 12 to define an open lumen between the proximal end 11 and the distal end 12. Although the stent graft 1 as seen in FIG. 1 is depicted as being substantially tubular, it should be understood that the stent graft 1 may be of any shape suitable for delivery to and placement at a target site in a patient. For example, portions of the graft member 10 at either or both of the proximal end 11 and the distal end 12 may be flared (inwardly or outwardly) or tapered (inwardly or outwardly). Additionally, portions of the graft member 10 may also include non-linear tubular portions, such as flared (inwardly or outwardly) portions, portions having bends or curves, perforations, channels, and / or branching portions, etc. Additionally, although proximal end 11 and distal end 12 are depicted as having a single open lumen, the present disclosure is not so limited. For example, one or both of proximal end 11 and distal end 12 may be a multi-lumen end, such as, for example, a bifurcated open end.

[0033] 1 shows the stent graft 1 in a longitudinally stretched state prior to pleating. The stent graft 1 includes a graft member 10, which also includes stent members 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, and 20l. In some embodiments, the stent members 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, and 20l are connected to one another as a single stent, while in other embodiments, they are separate from one another. In various embodiments, each of the stent members 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, and 20l is made of wavy wire wound circumferentially along an axis into an open tubular configuration. The circumferentially wound wavy wire may be circular or helical. The circumferentially wound wavy wire may form a zigzag with peaks and valleys. For example, stent member 20c is depicted as having multiple peaks 21 oriented toward the proximal end 11 of stent graft 1 and multiple valleys 22 oriented toward the distal end 12 of stent graft 1. In various embodiments, each of stent members 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, and 20l forms a crest with multiple peaks and valleys.

[0034] Each of the stent members 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, and 20l can be made from any other suitable material, including, for example, stainless steel, nickel-titanium alloys (NiTi) such as NITINOL, or cobalt-based alloys such as ELGILOY, platinum, gold, titanium, tantalum, niobium, and / or combinations thereof. Each of the stent members 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, and 20l can be balloon-expandable or self-expandable. In various embodiments, more than one stent member can be disposed at or near the proximal end 11 of the stent graft 1, such as two stent members as shown by stent member 20a. Also, in various embodiments, more than one stent member may be disposed at or near the distal end 12 of the stent graft 1, such as two stent members as shown by stent member 201. Although the embodiment of FIG. 1 shows a particular number of stent members, it should be appreciated that in various embodiments, any suitable number of stent members may be used.

[0035] In some embodiments, stent members 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, and 20l are attached to or laminated within graft member 10. In some embodiments, graft member 10 extends from proximal end 11 to distal end 12. In some other embodiments, graft member 10 does not cover the entire length of stent graft 1 and can leave, for example, proximal end 11, distal end 12, or both uncovered. In various embodiments, stent members 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, and 20l are fully laminated or fused within graft member 10. In this case, the possibility of graft material wear on graft member 10, which is a function of relative motion between the components, can be reduced. In various embodiments, stent members 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, and 20l are partially stacked, anchored, or free-floating within graft member 10.

[0036] In various embodiments, the graft member 10 includes a graft material made from one or more polymers or other suitable materials. In some embodiments, the graft member 10 is made from polytetrafluoroethylene (ePTFE). In some embodiments, the graft member 10 is made from expanded polytetrafluoroethylene (ePTFE). In yet some other embodiments, the stent graft 1 may include at least one additional polymer layer, such as a drug eluting layer, for eluting a bioactive agent from the stent graft 1 after implantation.

[0037] In some embodiments, the stent graft 1 can be longitudinally compressed to form multiple circumferential pleats having a predetermined orientation. In some embodiments, the stent graft 1 can be longitudinally compressed to form a continuous helical pleat in the case of a continuously wound wire. In various embodiments, each pleat involves a creased or folded surface of the graft material of the graft member 10 typically formed in the area of ​​the graft member 10 between the locations of the stent members 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, and 20l. Each portion of the stent graft 1 between two adjacent pleats is referred to herein as a pleated section of the stent graft 1. In various embodiments, each of the plurality of circumferential pleats is disposed between apexes formed by stent members 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, and 20l.

[0038] FIG. 2A is a flow diagram of a method according to an embodiment. FIGs. 2B and 2C show a method that can be used with the method of FIG. 2A. Referring to FIG. 2A, in step 100, the stent graft is compressed (e.g., axially or annularly) to form pleats in the graft material of the stent graft. In step 101, heat is applied to the stent graft to set the folds for the pleats in the graft material. In step 102, the stent graft is pulled (or stretched) to decompress the stent graft after the pleats are heat set. Referring to FIGs. 2A and 2B, in various embodiments, the heat application step of step 101 is performed as step 103 by applying an iron to the pleats of the stent graft to set the folds for the pleats in the graft material. Referring to FIGs. 2A and 2C, in various embodiments, the heat application step of step 101 is performed as step 104 by placing the stent graft in an oven and baking the stent graft for a predetermined time to heat set the pleats.

[0039] Figure 3 shows the stent graft 1 in an axially compressed state according to an embodiment. With reference to Figures 1, 2A and 3, the step 100 of axially compressing the stent graft 1 of Figure 1 may, according to an embodiment, result in an axially compressed version of the stent graft 1 as shown in Figure 3. In various embodiments, the stent graft 1 is axially compressed by bringing the distal end 12 closer to the proximal end 11, which creates pleats 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, and 30k, where the graft material of the graft member 10 folds between the stent members 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, and 20l, and where the stent members 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k, and 20l at least partially overlap (e.g., pass over or under) the corresponding adjacent stent members.

[0040] Figure 4 shows an iron 50 being used on the graft material of the graft member 10 of the stent graft 1 to heat set the pleats 30a, 30b, 30c, 30d, 30e, 3of, 30g, 30h, 30i, 30j, and 30k according to an embodiment. With reference to Figures 2A, 2B, and 4, in various embodiments, applying heat 101 to the stent graft 1 includes applying the iron 50 to each of the pleats 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, and 30k of the stent graft 1 to set the folds for the pleats 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, and 30k in the graft material of the graft member 10. In various embodiments, the iron 50 is applied (e.g., wiped across) each of the pleats 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, and 30k around the circumference of the stent graft 1. In various embodiments, the temperature of the iron 50 is set at a temperature between, for example, 320° C. and 390° C. In various other embodiments, other suitable temperatures are used for the iron 50.

[0041] Additionally and / or alternatively, the hand compressed stent graft 1 as seen in Figure 3 may be heated evenly or substantially evenly to harden the pleats 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, and 30k, such as by baking the stent graft 1 in an oven as shown in step 104 of Figure 2C. With reference to Figures 2C and 3, the oven temperature may be set based on the baking time and thickness of the graft member 10, and may be, for example, about 280°C-300°C, 300°C-320°C, 320°C-340°C, 340°C-360°C, or any other suitable temperature range. The baking time can be, for example, about 5-10 minutes, 10-15 minutes, 15-20 minutes, 20-25 minutes, 25-30 minutes, or any other suitable time range to set pleats 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, and 30k. In various exemplary embodiments, the three hand-compressed stent grafts are placed in a 320° C. oven for 5 minutes, 10 minutes, and 20 minutes, respectively. After baking, the three stent grafts are all heat set in a predetermined pleat orientation and can naturally maintain the same orientation when re-compressed.

[0042] 5 shows the stent graft 1 in a longitudinally stretched state after pleats 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, and 30k have been heat set. In some embodiments, pleats 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, and 30k are multiple circumferential pleats. In some embodiments, pleats 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, and 30k form a continuous spiral pleat. 2A, 4 and 5, in various embodiments, after pleats 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, and 30k have been heat set, a step 102 is performed on the stent graft 1 to pull (or stretch) the stent graft 1 and decompress it from an axially compressed state as in Figure 4 to an axially stretched state as in Figure 5. The stent graft 1 in Figure 5 is shown to include pleated sections 40a, 40b, 40c, 40d, 40e, 40f, 40g, 40h, 40i, 40j, 40k, and 40l.

[0043] Pleat section 40a of stent graft 1 includes stent member 20a and the portion of graft member 10 between proximal end 11 and pleat 30a. Pleat section 40b of stent graft 1 includes stent member 20b and the portion of graft member 10 between pleats 30a and 30b. Pleat section 40c of stent graft 1 includes stent member 20c and the portion of graft member 10 between pleats 30b and 30c. Pleat section 40d of stent graft 1 includes stent member 20d and the portion of graft member 10 between pleats 30c and 30d. Pleat section 40e of stent graft 1 includes stent member 20e and the portion of graft member 10 between pleats 30d and 30e. Pleat section 40f of stent graft 1 includes stent member 20f and the portions of graft member 10 between pleats 30e and 30f.

[0044] Pleat section 40g of stent graft 1 includes stent member 20g and the portion of graft member 10 between pleats 30f and 30g. Pleat section 40h of stent graft 1 includes stent member 20h and the portion of graft member 10 between pleats 30g and 30h. Pleat section 40i of stent graft 1 includes stent member 20i and the portion of graft member 10 between pleats 30h and 30i. Pleat section 40j of stent graft 1 includes stent member 20j and the portion of graft member 10 between pleats 30i and 30j. Pleat section 40k of stent graft 1 includes stent member 20k and the portion of graft member 10 between pleats 30j and 30k. The pleated section 40l of the stent graft 1 includes the stent member 20l and the portion of the graft member 10 between the pleats 30k and the distal end 12.

[0045] Stent grafts 1 with predetermined or preset pleat orientations according to various embodiments provide several advantages: circumferential pleats provide space for longitudinal movement between stent members or crests, thereby improving longitudinal flexibility during longitudinal compression and / or expansion, and also allow radial movement during bending or longitudinal compression, improving radial flexibility. Preset pleats provide an advantage over irregular pleats, because irregular pleats formed by compressing the stent graft, especially irregular pleats that protrude radially outward, tend to impede longitudinal compression and create internal forces within the stent graft that result in kinking. Various embodiments disclosed herein overcome the problem of irregular pleats by predetermining and fixing the pleat orientation before the stent graft is longitudinally compressed (or decompressed) or radially bent, thereby allowing a consistent and predetermined pleat orientation to be automatically formed when the stent graft is radially bent or longitudinally compressed for loading, delivery, or implantation. Uniform pleat orientation allows the stent material or apexes to move consistently relative to adjacent apexes without generating large shear forces in the graft material.

[0046] 6 shows the stent graft 1 according to an embodiment in a bent configuration after pleats 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, and 30k in the graft member 10 have been heat set to form pleated sections 40a, 40b, 40c, 40d, 40e, 40f, 40g, 40h, 40i, 40j, 40k, 40l in the stent graft 1. The heat set pleats provide the stent graft 1 with improved kink resistance when bent. In some embodiments, the stent graft 1 can fit around a pin, for example, 0.325 inch diameter, without kinking. In various embodiments, during bending, the pleats 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30i, 30j, and 30k in the graft member 10 move according to their preset orientation under bending forces. This allows the stent graft 1 to bend about 180° or more without having a substantial reduction in diameter anywhere in the bend. Thus, the luminal patency of the stent graft 1 is maintained or substantially maintained, especially in the area of ​​the bend. This results in a higher performing stent graft, since blood flow is only slightly or not reduced at the bend. In contrast, a stent graft without preset pleats (e.g., circumferential or helical) may have deformed portions when subjected to a similar degree of bending, where the deformed portions may cause partial closure of the lumen, resulting in suboptimal performance.

[0047] Longitudinally compressing the stent graft from a longitudinally stretched configuration to a compressed configuration can form pleats (e.g., pleats forming multiple circumferential pleats or continuous spiral pleats) in a predetermined orientation such that pleated sections nest within corresponding adjacent pleated sections along an axis. In various embodiments, any desired orientation of circumferential pleats can be thermally pretreated to fix the pleats in the desired orientation such that when the stent graft is longitudinally compressed again with natural setting, the compressed stent graft will remember and recover the preset pleat orientation, e.g., during loading, delivery, or implantation of the stent graft. In various embodiments, the stent graft is longitudinally compressed manually to form a uniform, outward luminal pleat orientation. Each of the circumferential pleats is then ironed to set the folds in the graft member. After the ironing step, the stent graft is manually pulled back to its stretched state. Such thermal pre-treatment allows the stent graft to remember the preset pleat orientation when naturally recompressed. The pleats may also be thermally pre-treated to form a uniform intraluminal orientation or a combination of extraluminal and intraluminal orientations as desired.

[0048] 7A shows an embodiment of a stent graft 70 having a graft member 73 with a proximal end 71 and a distal end 72, and pleated sections 74a, 74b, 74c, 74d, 74e, 74f, 74g, 74h, 74i, 74j, 74k, 74l, and 74m having zigzag valleys folded outwardly relative to adjacent zigzag peaks. The stent graft 70 includes pleated sections 74a, 74b, 74c, 74d, 74e, 74f, 74g, 74h, 74i, 74j, 74k, 74l, and 74m that are preset to be nested by intentional compression such that the pleated sections are all outwardly folded relative to one another (i.e., a more proximal pleated section is radially raised to cover a portion of its immediately distal adjacent pleated section). Pleat are thereby formed in stent graft 70 such that the valleys of the crests of the stent members are folded outwardly relative to one another. Figure 7B shows an inner surface 75 of graft member 73 of stent graft 70 of Figure 7A according to an embodiment having pleated sections 77a, 77b, 77c, 77d, 77e, 77f which form a "rough" inner surface due to the outwardly nesting orientation of pleated sections 74a, 74b, 74c, 74d, 74e, 74f, 74g, 74h, 74i, 74j, 74k, 741, and 74m.

[0049] FIG. 8A shows an embodiment of a stent graft 80 including a graft member 83 having a proximal end 81 and a distal end 82, and having pleated sections 84a, 84b, 84c, 84d, 84e, 84f, 84g, 84h, 84i, 84j, 84k, 84l, 84m, 84n, 84o, 84p, 84q, 84r, and 84s having zigzag valleys folded inwardly relative to adjacent zigzag peaks. Stent graft 80 includes pleated sections 84a, 84b, 84c, 84d, 84e, 84f, 84g, 84h, 84i, 84j, 84k, 84l, 84m, 84n, 84o, 84p, 84q, 84r, and 84s that are preconfigured to be nested by intentional compression such that the pleated sections are all inwardly folded relative to one another (i.e., the more distal pleated sections are radially raised and cover a portion of their immediately proximal adjacent pleated sections), thereby forming pleats in stent graft 80 such that the valleys of the crests of the stent material are inwardly folded relative to one another to reduce stresses developed in the stent material. Figure 8B shows the inner surface 85 of graft member 83 of stent graft 80 of Figure 8A in an embodiment having pleated sections 87a, 87b, 87c, 87d, 87e, and 87f that form a "smooth" inner surface throughout stent graft 80 due to the inner luminal nesting orientation of the pleated sections.

[0050] In yet some other embodiments, some of the pleated sections can be predetermined to be inwardly folded while others are outwardly folded. For example, in some embodiments, the proximal pleated section is inwardly folded while the distal pleated section is outwardly folded. Figure 9A shows an embodiment of a stent graft 90 including a graft member 93 with a proximal end 91 and a distal end 92, and having pleated sections 94a, 94b, 94c, 94d, 94e, 94f, 94g, 94h, 94i, 94j, 94k, 94l, 94m, 94n, 94o, 94p, 94q, and 94r. The stent graft 90 includes pleated sections 94a, 94b, 94c, 94d, and 94e that are predetermined to be nested by intentional compression such that the pleated sections are all inwardly folded relative to one another. Stent graft 90 includes pleat sections 94f, 94g, 94h, 94i, 94j, 94k, 941, 94m, 94n, 94o, 94p, 94q, and 94r that are preconfigured to nest by intentional compression such that all of the pleats are folded outwardly relative to one another. Figure 9B shows the inner surface 95 of the graft member 93 of the stent graft 90 of Figure 9A according to an embodiment having pleated sections 97a, 97b, 97c, 97d, 97e, 97f, 97g, and 97h, where pleated sections 97a, 97b, 97c, 97d, and 97e form a "smooth" inner surface due to the inward luminal nesting orientation of pleated sections 94a, 94b, 94c, 94d, 94e, and 94f, while other pleats form a "rough" inner surface due to the outward luminal nesting orientation of the remaining pleated sections. Various embodiments provide for mechanical interlocking with modular components.

[0051] In various embodiments, blood flow patterns within the stent graft can be controlled and modified by selecting the orientation of the pleats. For example, when the valleys of the stent apexes are folded outwardly, the inner surface of the stent graft lumen may be "rough" and disrupt blood flow. On the other hand, when the valleys of the stent apexes are folded inwardly, the inner surface of the stent graft lumen is "smooth," resulting in a desirable blood flow pattern and reduced shear stress on the graft material. Furthermore, when the pleats are helical pleats, the inner surface of the stent graft lumen has a helical pattern (which may have pleats folded inwardly or outwardly), which may induce or maintain a desirable helical blood flow pattern.

[0052] 10 illustrates the effect of graft spacing between stent members or crests on the achievable radius of curvature. The left stent graft 200 and the right stent graft 300 each have a larger curvature side 205 and 305 and a smaller curvature side 210 and 310, respectively. The left stent graft 200 has 2 mm of graft space 215 on the larger curvature side 205 between the crests of the stent body, and the right stent graft 300 has 4 mm of graft space 315 on the larger curvature side 305 between the crests of the stent body. The stent grafts 200 and 300 each have a smaller (or negative) graft space between the crests of the stent body on the smaller curvature side 210 and 310 opposite the larger curvature side 205 and 305, respectively. The increased graft spacing on the larger curvature side 305 allows the stent graft 300 to achieve a smaller radius of curvature compared to the stent graft 200 due to the larger pleats that allow the stent zigzag shape to be nested more. For example, the curvature of the stent graft 200 has an end-to-end length L1 (about 125 mm) and the curvature of the stent graft 300 has an end-to-end length L2 (about 80 mm), where L1 is greater than L2. In various embodiments, thermally pre-treating the longitudinally compressed stent graft allows the pleats to form in a predetermined orientation. In various embodiments, each pleated section can include one apex or more than one apex, pleated sections in different portions of the stent graft can include different numbers of apexes, or have different widths or spacing to otherwise accommodate the shape of the stent graft and achieve desired dimensions and physical properties.

[0053] Figure 11 shows an embodiment of a stent graft 1000 in an annular compressed configuration. In the annular compressed configuration, a stent graft 1000 having circular pleats can be formed. The stent graft 1000 having circular pleats has heat set partial pleats 130a, 130b, 130c, 130d, 130e, 130f, 130g, 130h, 130i, 130j, 130k, and 130l on the lesser curvature side 130 of the graft member 110, but has no pleats on the moreer curvature side 120 of the stent graft 1000. For example, the partial pleats 130a, 130b, 130c, 130d, 130e, 130f, 130g, 130h, 130i, 130j, 130k, and 130l can be heat set by applying heat to the partial pleats 130a, 130b, 130c, 130d, 130e, 130f, 130g, 130h, 130i, 130j, 130k, and 130l through an iron and / or by baking the annularly compressed stent graft 1000 having the partial pleats. The stent graft 1000 having circular pleats has improved conformability in a curved configuration with improved kink resistance. Thus, the luminal patency of the stent graft 1000 is maintained or substantially maintained while conforming to the curved configuration. This results in high performance of the stent graft since blood flow is only slightly or not reduced at the bends In contrast, a stent graft without pre-set circular pleats may have deformations when subjected to similar degrees of bend that may cause partial occlusion of the lumen resulting in suboptimal performance.

[0054] By annularly compressing the stent graft from a longitudinally stretched configuration to annularly compressed configuration, partial pleats of a predetermined orientation (e.g., pleats on the graft material of lesser curvature and no pleats on the graft material of greater curvature) can be formed, with the result that the partial pleats sections nest within the corresponding adjacent partial pleats sections along the curvature. In various embodiments, the partial pleats of any desired orientation are thermally pretreated to fix the partial pleats in one or more desired curved orientations, such that when the stent graft is annularly compressed again with natural setting, the compressed stent graft, for example, during loading, delivery, or implantation of the stent graft, will remember and recover the preset curved orientation. In various embodiments, the stent graft is annularly compressed by hand to form a uniform outward luminal partial pleat orientation. Each partial pleat is then heat set by application of heat (e.g., by ironing or baking) to set the partial pleats to the graft member. After the heat application step, the stent graft is manually pulled back to its stretched state. Such thermal pre-conditioning allows the stent graft to memorize the preset partial pleat orientation when it is naturally re-circumferentially compressed. The partial pleats may also be thermally pre-conditioned to form a uniform intraluminal partial pleat orientation or a combination of extraluminal and intraluminal partial pleat orientations as desired.

[0055] In some embodiments, the stent graft may be formed with circular pleats on one portion and axial pleats (e.g., circumferential or spiral pleats) on another portion. In this case, one portion of the stent graft may be annularly compressed to form circular pleats, as described above with reference to FIG. 11, and another portion of the stent graft may be axially compressed to form axial pleats, as described above with reference to FIG. 5. For example, such a stent graft may be particularly useful in the descending thoracic case, where the upper portion of the aorta is curved (and thus suitable for receiving the circular pleated portion of the stent graft), while the descending section is relatively straight (and thus suitable for receiving the axially pleated portion of the stent graft). However, it should be appreciated that the present disclosure is not so limited and that, according to various embodiments, the stent graft may include any number of circular and axial pleated portions as needed or desired.

[0056] Various embodiments provide stent grafts with improved flexibility due to pleats that allow the nitinol zigzag pattern of the stent material to move freely across the pleats formed in the intimal. The various pleats are formed to create a preferential nesting pattern to maximize flexibility. In some embodiments, a portion of the pleat is extimal (e.g., nitinol apical valleys), while adjacent portions of the pleat are intimal (e.g., nitinol apical peaks). In various embodiments, the stent is fully laminated or fused to the graft material, thereby reducing concerns regarding wear, as the wear rate is a function of relative motion between the components and subsequent erosion. In some embodiments, a stent fully laminated or fused to the graft material has an advantage over embodiments in which the stent is partially laminated, tethered, or free-floating within the graft material, as it experiences less wear.

[0057] Various embodiments provide for creating pleats in a preferred orientation to create a smooth lumen in the stent graft. This allows for the reduction or elimination of undesirable irregular pleats that may protrude into the lumen in a manner that obstructs blood flow. Various embodiments provide the advantages of improved kink resistance and improved flexibility. Various embodiments provide a fast method of setting the pleats. For example, in various embodiments, a non-contact oven pleating method allows for the pleats to be set in as little as five minutes.

[0058] The embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive of the present invention. The present invention is not limited in any way to the above-described embodiments. Various modifications and changes can be made to the embodiments without departing from the spirit and scope of the present invention, which is defined by the following claims and their equivalents. [Explanation of symbols]

[0059] 1. Stent graft 10 Graft member 30a Pleats 50 Iron

Claims

1. 1. A stent graft for surgical delivery to a target site in a patient to treat an abdominal aortic aneurysm, comprising: A graft formed by a graft material, the graft material comprising: a relatively straight first section configured to be received by the lower portion of the aorta; a curved second portion configured to be received by the upper portion of the aorta; a graft comprising: a stent attached to the graft and including a plurality of stent members; Including, a first portion of the graft material in a first orientation, the first portion of the graft material being folded over a first adjacent portion of the graft between the stent members to form a first pleat; a second portion of the graft material in a first orientation, the second portion of the graft material being folded over a second adjacent portion of the graft between the stent members to form a second pleat; In a second portion second orientation, the second plication has a graft space between corresponding stent members on a side of greater curvature of the stent graft that is greater than a graft space between corresponding stent members on a side of lesser curvature of the stent graft. Stent graft.

2. The stent graft of claim 1 , wherein the second pleat is a partial pleat located on the lesser curvature side of the stent graft.

3. The stent graft of claim 2 wherein in said second portion second orientation, a side of said stent graft with greater curvature is free of said portion pleats.

4. The stent graft of claim 1 further comprising a drug eluting layer for eluting a bioactive agent from the stent graft after implantation.

5. The stent graft of claim 1 , wherein the graft material comprises polytetrafluoroethylene (PTFE) or expanded polytetrafluoroethylene (ePTFE).

6. 1. A stent graft for surgical delivery to a target site in a patient to treat an abdominal aortic aneurysm, comprising: a graft formed by a graft material; a stent attached to the graft and including a plurality of stent members; Including, In a first orientation, the graft material is folded over adjacent portions of the graft between the stent members to form pleats; In the second orientation, the pleats have a larger graft space between corresponding stent members on the greater curvature side of the stent graft than on the lesser curvature side of the stent graft. Stent graft.

7. The stent graft of claim 6, wherein the pleat is a partial pleat located on the lesser curvature side of the stent graft.

8. The stent graft of claim 7, wherein in the second orientation, the side of the stent graft with greater curvature is free of the partial pleats.

9. The stent graft of claim 6 , wherein the side of greater curvature is opposite the side of lesser curvature.

10. The stent graft of claim 6 wherein the pleats are heat set within the graft material.

11. The stent graft of claim 6, wherein the graft spacing is at least 4 mm.

12. The stent graft of claim 6 wherein in the first orientation, the graft material is axially compressed.

13. The stent graft of claim 6 wherein in the second orientation, the graft material is annularly compressed.

14. The stent graft of claim 6, wherein in the first orientation, the graft material is folded outwardly relative to the lumen of the stent graft.

15. The stent graft of claim 6, wherein in the first orientation, the graft material is folded intraluminally relative to the lumen of the stent graft.

16. 7. The stent graft of claim 6, wherein in the first orientation, a first portion of the graft material is folded outwardly relative to the lumen of the stent graft and a second portion of the graft material is folded inwardly relative to the lumen of the stent graft.

17. 7. The stent graft of claim 6, further comprising a polymeric layer for eluting a bioactive agent from the stent graft after implantation, the polymeric layer comprising a drug eluting layer.

18. The stent graft of claim 6, wherein the graft material comprises polytetrafluoroethylene (PTFE) or expanded polytetrafluoroethylene (ePTFE).

19. 1. A stent graft for surgical delivery to a target site in a patient to treat an abdominal aortic aneurysm, comprising: a graft formed by a graft material; a stent attached to the graft and including a plurality of stent members; Including, In a first orientation, the graft material is folded over adjacent portions of the graft between the stent members to form partial pleats; In a second orientation, the graft material is annularly compressed and the partial pleats have a larger graft space between corresponding stent members on a side of greater curvature of the stent graft than on a side of lesser curvature of the stent graft, the side of greater curvature of the stent graft being free of the partial pleats. Stent graft.

20. 20. The stent graft of claim 19, further comprising a drug eluting layer for eluting a bioactive agent from the stent graft after implantation, wherein the graft material comprises polytetrafluoroethylene (PTFE) or expanded polytetrafluoroethylene (ePTFE).

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