Patent Publication Number: US-2020281711-A1

Title: Longitudinally extendable stent graft systems and methods

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Application Ser. No. 62/453,460, filed on Feb. 1, 2017, the entire contents of which are incorporated by reference herein. 
    
    
     FIELD 
     Various embodiments in the present disclosure relate to stent grafts, systems including stent grafts, and methods of using such systems having stent grafts for treating aneurysms. 
     BACKGROUND 
     Aneurysms are enlargements or bulges in blood vessels that are often prone to rupture and which therefore present a serious risk to a patient. Aneurysms may occur in any blood vessel but are of particular concern when they occur in the cerebral vasculature or the patient&#39;s aorta. 
     Abdominal aortic aneurysms (AAA&#39;s) are classified based on their location within the aorta as well as their shape and complexity. Aneurysms that are found below the renal arteries are referred to as infrarenal abdominal aortic aneurysms. Suprarenal abdominal aortic aneurysms occur above the renal arteries. Thoracic aortic aneurysms (TAA&#39;s) occur in the ascending, transverse, or descending part of the upper aorta. Infrarenal aneurysms are the most common, representing about 70% of all aortic aneurysms. Suprarenal aneurysms are less common, representing about 20% of the aortic aneurysms. Thoracic aortic aneurysms are the least common and often the most difficult to treat. 
     The most common form of aneurysm is “fusiform,” where the enlargement extends about the entire aortic circumference. Less commonly, the aneurysms may be characterized by a bulge on one side of the blood vessel attached at a narrow neck. Thoracic aortic aneurysms are often dissecting aneurysms caused by hemorrhagic separation in the aortic wall, usually within the medial layer. A common treatment for each of these types and forms of aneurysm is open surgical repair. Open surgical repair is often quite successful in patients who are otherwise reasonably healthy and free from significant co-morbidities. Such open surgical procedures are problematic, however, since access to the abdominal and thoracic aortas is difficult to obtain and because the aorta must be clamped off, placing significant strain on the patient&#39;s heart. 
     Endoluminal gratis have come into widespread use for the treatment of aortic aneurysms in patients. In general, endoluminal repairs access the aneurysm “endoluminally” through either or both common iliac arteries. The grafts are then implanted. Successful endoluminal procedures have a much shorter recovery period than open surgical procedures. 
     SUMMARY OF THE DISCLOSURE 
     One or more aspects of example embodiments are directed to stent grafts, stent graft systems, and methods of using stent graft systems. According to an example embodiment, a stent graft system includes a stent graft, a radially expandable scaffold, and an inflatable fill structure. Ira various embodiments, the stent graft includes a body portion with a plurality of pleated sections that are configured to be extended from a telescopically compressed state to a longitudinally extended state. In various embodiments, the radially expandable scaffold is attached to a top of the body portion of the stent graft, and has one or more fixation elements for penetrating into an aortic wall. In various embodiments, the inflatable fill structure is attached at a top of the body portion of the stent graft and is configured to expand in a longitudinal direction as the body portion of the stent graft is extended in the longitudinal direction. 
     In various embodiments, the inflatable fill structure is not attached at or to a central part or middle part of the body portion of the stent graft. In various embodiments, the inflatable fill structure is further attached at a lower part of the body portion of the stent graft. In various embodiments, an amount that the inflatable fill structure expands in the longitudinal direction corresponds to an amount that the body portion is extended in the longitudinal direction. 
     In some embodiments, the inflatable structure includes an inner wall adjacent to an outer surface of the body portion, and also includes an outer wall. In some embodiments, the inner wall is configured to contact the outer surface of the body portion when the inflatable fill structure is inflated to provide columnar support to the body portion. In various embodiments, the outer wall is configured to conform to an inner surface of a vessel in which the stent graft is inserted. 
     In various embodiments, the stent graft further includes a first leg portion, a second leg portion, and a transition portion connecting the first leg portion and the second leg portion to the body portion. In various embodiments, at least one of the first leg portion and the second leg portion is configured to be extendable from a telescopically compressed state to a longitudinally extended state. 
     In various embodiments, a length of the body portion in the telescopically compressed state is less than one-fourth of a length of the body portion in the longitudinally extended state. In various embodiments, a length of the body portion in the telescopically compressed state is less than one-half of a length of the body portion in the longitudinally extended state. 
     A method in accordance with various embodiments for deploying a stent graft system to repair an aneurysm includes inserting, into an aorta, the stent graft system with a body portion of the stent graft system in a telescopically compressed state, longitudinally extending the body portion of the stent graft system from the telescopically compressed state to a longitudinally extended state, and filling an inflatable fill structure surrounding at least a portion of the body portion to provide columnar support for the body portion. 
     In various embodiments, the inflatable fill structure is attached to at least a top of the body portion. In various embodiments, the inflatable fill structure is not attached at a central part of the body portion. In various embodiments, the inflatable fill structure expands or extends in a longitudinal direction as the body portion is extended in the longitudinal direction. in various embodiments, an amount that the inflatable fill structure expands in the longitudinal direction corresponds to an amount that the body portion extends in the longitudinal direction. 
     In various embodiments, the longitudinally extending of the body portion includes pulling a first leg portion connected to a lower part of the body portion into an iliac artery and pulling a second leg portion connected to a lower part of the body portion into another iliac artery, In various embodiments, the filling of the inflatable fill structure includes expanding the inflatable fill structure in a longitudinal direction as the body portion is extended in the longitudinal direction, filling the inflatable fill structure with saline to expand the inflatable fill structure in a radial direction, evacuating the saline from the inflatable fill structure, and filling the inflatable fill structure with a hardenable fill medium. 
     In various embodiments, the hardenable fill medium includes a polymer such as a liquid polymer that hardens as it is dried or cured. In various embodiments, the inflatable fill structure is radially expanded to conform to an inner surface of the aorta after being longitudinally extended along with the body portion. In various embodiments, the method further includes longitudinally extending a first leg portion of the stent graft system from a telescopically compressed state to a longitudinally extended state, and longitudinally extending a second leg portion of the stent graft system from a telescopically compressed state to a longitudinally extended state, where the first leg portion and the second leg portion are connected to the body portion of the stent graft system. 
     A method in accordance with various embodiments for repairing an aneurysm includes inserting, into an aorta, a stent graft system. In various embodiments, the stent graft system includes a body portion that is configured to be extended from a telescopically compressed state to a longitudinally extended state, an inflatable fill structure surrounding the body portion, a first leg portion connected to the body portion, and a second leg portion connected to the body portion. In various embodiments, the method further includes longitudinally extending the body portion of the stem graft system from the telescopically compressed state to the longitudinally extended state by pulling the first leg portion into an iliac artery and pulling the second leg portion into another iliac artery. In various embodiments, the method also includes filling the inflatable fill structure so that the inflatable fill structure radially expands to conform to an inner surface of the aorta and provides columnar support for the body portion. 
     A stent graft system in accordance with an embodiment includes a stent graft, a radially expandable scaffold, and an inflatable fill structure. The stent graft includes a body portion with a plurality of pleated sections that are configured to be extended from a telescopically compressed state to a longitudinally extended state. The radially expandable scaffold is attached to a top of the body portion and has one or more fixation elements for penetrating into an aortic wall. The inflatable fill structure is positioned at top section of the body portion and is configured to not expand in a longitudinal direction as the body portion is extended in the longitudinal direction. In various embodiments, the inflatable fill structure is configured to provide a seal at a proximal neck of an aneurysm. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration of a cross section of an example anatomy with an infrarenal aortic aneurysm; 
         FIG. 2  is an illustration of a stent graft in accordance with an embodiment in a longitudinally extended state; 
         FIG. 3  is an illustration of the stent graft of  FIG. 2  in accordance with an embodiment in a compressed state; 
         FIG. 4  is an illustration of a stent graft in accordance with another embodiment in a compressed state; 
         FIG. 5  is an illustration of a stent graft system in accordance with an embodiment in a longitudinally extended state; 
         FIG. 6  is an illustration of the stent graft system of  FIG. 5  in a longitudinally extended state in an aorta and iliac arteries; 
         FIG. 7  is an illustration of the stent graft system of  FIG. 5  in accordance with an embodiment in a compressed state in an aorta and fixed to the aorta at a proximal end of the stent graft system; 
         FIG. 8  is an illustration of the stent graft system of  FIG. 5  in accordance with an embodiment in a compressed state in an aorta and iliac arteries and placed over an aortic bifurcation; 
         FIG. 9  is an illustration of the stent graft system of  FIG. 6  in accordance with an embodiment after the inflatable fill structure has been filled with a hardenable fill medium; 
         FIGS. 10A, 10B, 10C, 10D, 10E, and 10F  are illustrations showing some steps during placement, extension, and filling of the stent graft system of  FIG. 5  in an aneurysm, in accordance with various illustrative embodiments; 
         FIG. 11  is a flow diagram illustrating a method of using the stent graft system of  FIGS. 10A, 10B, 10C, and 10D , in accordance with an illustrative embodiment; 
         FIG. 12  is an illustration of a stern graft system in accordance with another embodiment in a compressed state; 
         FIG. 13  is an illustration of the stent graft system of  FIG. 12  in a longitudinally extended state; 
         FIGS. 14A, 14B, 14C, and 14D  illustrate flowcharts of methods in accordance with various embodiments; and 
         FIG. 15  is an illustration of a stent graft system in accordance with another embodiment in an aorta. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, example embodiments will be described in more detail with reference to the accompanying drawings. The present invention, however, may be embodied in various different forms, and should not be construed as being limited to only the illustrated embodiments herein. Rather, these embodiments are provided as examples so that this disclosure will be thorough and complete, and will fully convey the aspects and features of the present disclosure to those skilled in the art. Unless otherwise noted, like reference numerals denote like elements throughout the attached drawings and the written description, and thus, descriptions thereof may not be repeated. 
     It will be understood that the aspects and features of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure. Accordingly, descriptions of features or aspects within each example embodiment should typically be considered as available for other similar features or aspects in other example embodiments. 
       FIG. 1  is an illustration of a cross section of an example anatomy with an infrarenal aortic aneurysm. In  FIG. 1 , an aorta  10  branches at an aortic bifurcation  11  into two iliac arteries  12  and  13 . An aneurysm sac  14  denotes a bulged section of the aorta  10 . As the name implies, the infrarenal aortic aneurysm is located below renal arteries  15  and  16 . A segment of the aorta  10  between the renal arteries  15  and  16  and the aneurysm sac  14  is referred to as a proximal neck  17 . Often mural thrombus  18  forms on an inside wall of the aneurysm sac  14 . A diameter of a flow lumen in the aneurysm is, thus, reduced by the mural thrombus  18  to a diameter less than a diameter of the aneurysm sac  14 . 
     The dimensions of an aortic aneurysm can vary greatly from patient to patient. The diameter of the proximal neck  17  may vary, for example, from 18 millimeters (mm) to 34 mm. The distance from the aortic bifurcation  11  to the renal arteries  15  and  16  may vary, for example, from 80 mm to 160 mm. The diameters of the iliac arteries  12  and  13  might not be the same as each other. The diameters of the iliac arteries  12  and  13  may vary, for example, from 8 mm to 20 mm, One iliac artery or both iliac arteries  12  and  13  may be aneurysmal with greatly enlarged diameters, for example, of more than 30 mm. 
       FIG. 2  illustrates an embodiment of a stent graft  20  in accordance with an embodiment in a longitudinally extended state. The stent graft  20  includes a graft  21 . In various embodiments, the graft  21  is made of a polymer. In some embodiments, the graft  21  is made of expanded Polytetrafluoroethylene (ePTFE). The stent graft  20  includes pleated sections  22   a,    22   b,    22   c,    22   d,    22   e,    22   f,    22   g,    22   h,    22   i,    22   j,    22   k,    22   l,    22   m,  and  22   n.  Each of the pleated sections  22   a,    22   b,    22   c,    22   d,    22   e,    22   f,    22   g,    22   h,    22   i,    22   j,    22   k,    22   l,    22   m,  and  22   n  includes a scaffold  23   a,    23   b,    23   c,    23   d,    23   e,    23   f,    23   g,    23   h,    23   i,    23   j,    23   k,    23   l,    23   m,  and  23   n,  respectively, that is encapsulated within or attached to a corresponding portion of the graft  21 . The scaffolds  23   a,    23   b,    23   c,    23   d,    23   e,    23   f,    23   g,    23   h,    23   i,    23   j,    23   k,    23   l,    23   m,  and  23   n  may each comprise, for example, a sinusoidal stent frame in a ring shape and may be made from, for example, cobalt-chromium (CoCr) alloy, stainless steel, nitinol, or the like. Each of the scaffolds  23   a,    23   b,    23   c,    23   d,    23   e,    23   f,    23   g,    23   h,    23   i,    23   j,    23   k,    23   l,    23   m,  and  23   n  is radially expandable. When longitudinally extended, the graft  21  is a generally tubular shape that allows for blood flow through a lumen within the graft  21 . 
     Each of the pleated sections  22   a,    22   b,    22   c,    22   d,    22   e,    22   f,    22   g,    22   h,    22   i,  ??j,  22   k,    22   l,  and  22   m  ends with a pleat  24   a,    24   b,    24   c,    24   d,    24   e,    24   f,    24   g,    24   h,    24   i,    24   j,    24   k,    24   l,  and  24   m,  respectively, in the graft  21 . The pleats  24   a,    24   b,    24   c,    24   d,    24   e,    24   l,    24   g,    24   h,    24   i,    24   j,    24   k,    24   l,  and  24   m  in the graft  21  allow for the graft  21  to fold in at those locations, so that the stent graft  20  can be telescoping to be placed in a compressed state, and to allow for movement from the compressed state to the longitudinally extended state. 
       FIG. 3  illustrates an embodiment of the stent graft  20  in accordance with an embodiment in the compressed state. The graft  21  is pleated such that the pleated section  22   b  can fold at least partially up under the pleated section  22   a,  the pleated section  22   c  can fold at least partially up under the pleated section  22   b,  the pleated section  22   d  can fold at least partially up under the pleated section  22   c,  the pleated section  22   e  can fold at least partially up under the pleated section  22   d,  and so on for each adjacent pleated section. In the compressed state, each of the pleated sections may have a slightly smaller diameter than the above adjacent pleated section so that they can fit within each other in a telescoping manner, and when the pleated section is extended (e.g., fully or partially) in the longitudinal direction, its diameter may expand radially. The stent graft  20  in the compressed state in  FIG. 3  can be extended in the longitudinal direction until fully extended as shown in  FIG. 2 . In various embodiments, a length of the stent graft  20  in the compressed state may be less than one-fourth of the length of the stent graft  20  in the extended state. In some embodiments, a length of the stent graft  20  in the compressed state may be less than one-half of the length of the stern graft  20  in the extended state. 
     The pleating direction of the pleats  24   a,    24   b,    24   c,    24   d,    24   e,    24   f,    24   g,    24   h,    24   i,    24   j,    24   k,    24   l,  and  24   m  in the embodiment of  FIGS. 2 and 3  is formed such that the crown valleys are tucked abluminally in the compressed state.  FIG. 4  shows another embodiment of a stent graft  40  in a compressed state that includes a graft  41  and pleated sections  12   a,    42   b,    42   c,    42   d,    42   e,    42   f,  and so on. Pleats for the pleated sections in the embodiment of  FIG. 4  are formed such that the crown and valleys are tucked adluminally. In various other embodiments, the pleats may be formed such that crown valleys are tucked adluminally on one end (e.g., a proximal end) of the stent graft and are tucked abluminally on an opposite end (e.g., a distal end) of the stent graft. 
       FIG. 5  illustrates an embodiment of a stent graft system  50  in accordance with an embodiment in a longitudinally extended state. The stent graft system  50  includes a stent graft  53  with a body portion  60  and a bifurcation portion  80 . The bifurcation portion  80  includes a transition portion  81 , a first leg portion  82 , and a second leg portion  83 . The stent graft system  50  includes a graft  61 . In various embodiments, the graft  61  is used for the body portion  60  and the bifurcation portion  80 . In some embodiments, one or more other grafts may be used for each of the portions of the stent graft system  50 . In various embodiments, the graft  61  is made of a polymer. In some embodiments, the graft  61  is made of expanded Polytetratluoroethylene (ePTFE). The body portion  60  includes pleated sections  62   a,    62   b,    62   c,    62   d,    62   e,    62   f,    62   g,    62   h,  and  62   i.  Each of the pleated sections  62   a,    62   b,    62   c,    62   d,    62   e,    62   f,    62   g,    62   h,  and  62   i  includes a scaffold  63   a,    63   b,    63   c,    63   d,    63   e,    63   f,    63   g,    6311 , and  63   i,  respectively, that is encapsulated within or attached to a corresponding portion of the graft  61 . The scaffolds  63   a,    63   b,    63   c,    63   d,    63   e,    63   f,    63   g,    63   h,  and  63   i  may each comprise, for example, a sinusoidal stent frame in a ring shape and may be made from, for example, cobalt-chromium (CoCr) alloy, stainless steel, nitinol, or the like. Each of the scaffolds  63   a,    63   b,    63   c,    63   d,    63   e,    63   f,    63   g,    63   h,  and  63   i  is radially expandable. 
     Each of the pleated sections  62   a,    62   b,    62   c,    62   d,    62   e,    62   f,    62   g,  and  62   h  ends with a pleat  64   a,    64   b,    64   c,    64   d,    64   e,    64   f,    64   g,  and  64   h,  respectively, in the graft  61 . The pleats  64   a,    64   b,    64   c,    64   d,    64   e,    64   f,    64   g,  and  64   h  in the graft  61  allow for the graft  61  to fold in at those locations, so that the body portion  60  can be telescoping to be in a compressed state, and to allow for movement from the compressed state to the longitudinally extended state. In various embodiments, a length of the body portion  60  in the compressed state may be less than one-fourth of the length of the body portion  60  in the extended state. In various embodiments, a length of the body portion  60  in the compressed state may be less than one-half of the length of the body portion  60  in the extended state. When extended, the portion of the graft  61  for the body portion  60  is a generally tubular shape that allows for blood flow through a lumen within the body portion  60 . The stent graft system  50  includes a radially expandable scaffold  51  connected to the top of the body portion  60  for providing fixation of the stent graft system  50  in an aorta along an aortic wall. The radially expandable scaffold  51  may, for example, have hooks or barbs  52  for penetrating into an aortic wall and thereby enhancing fixation. 
     The transition portion  81  includes a portion of the graft  61  that extends from the body portion  60  to each of the first leg portion  82  and the second leg portion  83 . The transition portion  81  may be made of the same or different material from that of the graft  61 . For example, in various embodiments, the transition portion  81  may be made of, for example, Teflon. The first leg portion  82  includes scaffolds  84  that are encapsulated within or attached to a corresponding portion of the graft  61 . The scaffolds  84  may each comprise, for example, a sinusoidal stent frame in a ring shape and may be made from, for example, cobalt-chromium (CoCr) alloy, stainless steel, nitinol, or the like. Each of the scaffolds  84  is radially expandable. The second leg portion  83  includes scaffolds  85  that are encapsulated within or attached to a corresponding portion of the graft  61 . The scaffolds  85  may each comprise, for example, a sinusoidal stent frame in a ring shape and may be made from, for example, cobalt-chromium (CoCr) alloy, stainless steel, nitinol, or the like. Each of the scaffolds  85  is radially expandable. Each of the first leg portion  82  and the second leg portion  83  is a generally tubular shape that allows for blood flow through a lumen within the first leg portion  82  and the second leg portion  83 , respectively. The stent graft system  50  has a proximal end  91  for receiving blood flow and distal ends  92  and  93  out of which the blood is able to flow. 
     The stent graft system  50  includes an inflatable fill structure  70 . The inflatable fill structure  70  may surround (e.g., entirely surround) the outer circumference of the body portion  60 , and may be a single inflatable fill structure or a plurality of inflatable fill structures arranged around the body portion  60 . The inflatable fill structure  70  includes an inner wall  71  and an outer wall  72 . In various embodiments, the inflatable fill structure  70  is an endobag or the like. The inflatable fill structure  70  is attached at locations  73  near the top of the body portion  60  and is attached at locations  74  near the top of the leg portions  82  and  83 . In various embodiments, the inflatable fill structure  70  is attached at the locations  73  and  74  and remains unattached from a middle part or central part of the body portion  60  to allow for the body portion  60  to be longitudinally extended. In various embodiments, the inflatable fill structure  70  is stitched to the graft  61  at the locations  73  and  74 . In various embodiments, the inflatable fill structure  70  is fillable through a fill tube with a hardenable filling material such as Polyethylene glycol (PEG) or another polymer that may be polymerized in situ. 
     According to various embodiments, the inflatable fill structure  70  is highly stretchable (e.g., up to 5000% from an initial state) to conform to each of the compressed state and the longitudinally extended state of the body portion  60 , while having reduced retraction forces and packing densities than those of other till structures. For example, the inflatable fill structure  70  may have low flexural modulus, providing expansion (e.g., longitudinally and radially) at low pressures (e.g., 3 to 100 mm Hg, or more desirably, 3 to 5 mm Hg). Thus, in various embodiments, when the body portion  60  is in a compressed state (e.g., a fully compressed state), a length of the inflatable fill structure  70  in the longitudinal direction may be at its shortest. For example, when the body portion  60  is in a compressed state (e,g., a fully compressed state), the inflatable fill structure  70  may be in an initial state (e.g., relaxed or unstretched state). As the body portion  60  is extended in the longitudinal direction, the inflatable fill structure  70  is extended or expanded (e.g., stretched or pulled) in the longitudinal direction, so that the length of the inflatable fill structure  70  increases in the longitudinal direction according to an amount that the body portion  60  is extended. 
     According to various embodiments, the inflatable fill structure  70  may be made of, for example, polyurethane, silicon., Teflon, and/or combinations thereof. The polyurethane may include, for example, Pellethane® 5863 80A or softer, and/or Estane® 58123 70A or the like. The silicone may include any from among NuSil&#39;s MED-4714, MED-4720, MED-4810, MED-4820, combinations thereof, or the like. Accordingly, the inflatable fill structure  70  may be thinner and more elastic than that of other fill structures. In various embodiments, the inflatable fill structure  70  is made of an aromatic polyether-based thermoplastic polyurethane (TPU). In various embodiments, the inflatable fill structure  70  is made of silicone rubber or a silicone elastomer. In some embodiments, the Shore durometer hardness of the inflatable fill structure  70  is 80A or softer. In some embodiments, the Shore durometer hardness of the inflatable fill structure  70  is within a range of 10A to 80A. In various embodiments, the ultimate elongation of the material for the inflatable fill structure  70  is within a range of 700% to 1,400%. 
       FIG. 6  is an illustration of the stent graft system  50  in accordance with an embodiment in a longitudinally extended state in the aorta  10  and the iliac arteries  12 . and  13 . In various embodiments, the body portion  60  of the stent graft system  50  is able to be extended and/or expand across the aneurysm sac  14  to exclude the aneurysm sac  14  from aortic blood pressure. The stent graft system  50  includes the body portion  60  that can be placed in the aorta  10 , and first and second leg portions  82  and  83  extending from the body portion  60  that can be placed into the iliac arteries  12  and  13 , respectively. A proximal end of the body portion  60  can radially expand against a wall of the aorta  10  at the proximal neck  17  to create a proximal seal. Distal ends  92 . and  93  of the first and second leg portions  82  and  83  can radially expand against walls of the iliac arteries  12  and  13 , respectively, to form distal seals in the distal seal zones  102  and  104  adjacent thereto. The barbs  52  of the radially expandable scaffold  51  can penetrate into the wall of the aorta  10 , thereby enhancing fixation of the stent graft system  50 . Blood is able to flow from the proximal end  91  through the body portion  60  and out of the distal ends  92  and  93  of the first and second leg portions  82  and  83 , respectively. The inflatable fill structure  70  is initially in an uninflated state, but may be expanded or extended (e.g., stretched or pulled) in the longitudinal direction according to the amount of extension of the body portion  60 . 
       FIG. 7  is an illustration of the stem graft system  50  in accordance with an embodiment in a compressed state in the aorta  10  and fixed to the aorta  10  at a proximal end of the stent graft system  50 . In various embodiments, the stent graft system  50  is initially inserted into the aorta  10  in the compressed state in which the body portion  60  of the stent graft system  50  is compressed, and the inflatable fill structure  70  is in the initial state e.g., relaxed or unstretched state) as shown in  FIG. 7 . With reference to  FIGS. 5 and 7 , the portion of the graft  61  for the body portion  60  is pleated such that the pleated section  62   b  can fold at least partially up under the pleated section  62   a,  the pleated section  62   c  can fold at least partially up under the pleated section  62   b,  the pleated section  62   d  can fold at least partially up under the pleated section  62   c,  the pleated section  62   e  can fold at least partially up under the pleated section  62   d,  the pleated section  62   f  can fold at least partially up under the pleated section  62   e,  the pleated section  62   g  can fold at least partially up under the pleated section  62   f,  the pleated section  62   h  can fold at least partially up under the pleated section  62   g,  and the pleated section  62   i  can fold at least partially up under the pleated section  62   h.    FIG. 7  shows the body portion  60  in a telescopically compressed state and the body portion  60  is configured to be extendable from the compressed state of  FIG. 7  to the longitudinally extended state of  FIG. 6 , In the compressed state, each of the pleated sections of the body portion  60  may have a slightly smaller diameter than the above adjacent pleated section so that they can fit within each other in a telescoping manner, In the expanded state, each of the pleated sections of the body portion  60  may be radially expanded. In the expanded state, each of the pleated sections may have the same or substantially the same diameter as those of adjacent pleated sections. However, the present invention is not limited thereto, for example, at least one of the pleated sections of the body portion  60  may have a smaller diameter even in the expanded state than that of an adjacent pleated section. 
     With reference to  FIGS. 6 and 7 , the inflatable fill structure  70  is sized and configured such that the inflatable fill structure  70  is able to longitudinally extend or expand as the body portion  60  is longitudinally extended. For example, the inflatable fill structure  70  may be expanded or extended (e.g., stretched or pulled) in the longitudinal direction according to the amount of extension of the body portion  60 . The barbs  52  of the radially expandable scaffold  51  can penetrate into the wall of the aorta  10 , thereby enhancing fixation of the stem graft system  50 . In various embodiments, the distal ends  92  and  93  of the first and second leg portions  82  and  83 , respectively, are pulled to cause the body portion  60  to longitudinally extend from the telescoped compressed state to the longitudinally extended state, and to place the first and second leg portions  82  and  83  in the iliac arteries  12  and  13 , respectively. 
       FIG. 8  is an illustration of the stent graft system  50  in accordance with an embodiment in a compressed state in the aorta  10  and iliac arteries  12  and  13  and located over the aortic bifurcation. In various embodiments, the stent graft system  50  is initially inserted into the aorta  10  in the compressed state in which the body portion  60  of the stent graft system  50  is compressed as shown in  FIG. 8 . With reference to  FIGS. 5 and 8 , the portion of the graft  61  for the body portion  60  is pleated such that the pleated section  62   b  can fold at least partially up under the pleated section  62   a,  the pleated section  62   c  can fold at least partially up under the pleated section  62   b,  the pleated section  62   d  can fold at least partially up under the pleated section  62   c,  the pleated section  62   e  can fold at least partially up under the pleated section  62   d,  the pleated section  62   f  can fold at least partially up under the pleated section  62   e,  the pleated section  62   g  can fold at least partially up under the pleated section  62   f,  the pleated section  62   h  can fold at least partially up under the pleated section  62   g,  the pleated section  62   i  can fold at least partially up under the pleated section  62   h.    FIG. 8  shows the body portion  60  in a telescopically compressed state and the body portion  60  is configured to be extendable from the compressed state of  FIG. 8  to the longitudinally extended state of  FIG. 6 . In the compressed state, each of the pleated sections of the body portion  60  may have a slightly smaller diameter than the above adjacent pleated section so that they can fit within each other in a telescoping manner. In the expanded state, each of the pleated sections of the body portion  60  may be radially expanded. In the expanded state, each of the pleated sections may have the same or substantially the same diameter as those of adjacent pleated sections. However, the present invention is not limited thereto, for example, at least one of the pleated sections of the body portion  60  may have a smaller diameter even in the expanded state than that of an adjacent pleated section. 
     With reference to  FIGS. 6 and 8 , the inflatable fill structure  70  is sized and configured such that the inflatable fill structure  70  is able to longitudinally extend or expand as the body portion  60  is longitudinally extended. For example, the inflatable fill structure  70  may be expanded or extended (e.g., stretched or pulled) in the longitudinal direction according to the amount of extension of the body portion  60 . The distal ends  92  and  93  of the first and second leg portions  82  and  83  are positioned in the iliac arteries  12  and  13 , respectively. In various embodiments, the radially expandable scaffold  51  can be pulled up to cause the body portion  60  to longitudinally extend from the telescoped compressed state to the longitudinally extended state, and to place the radially expandable scaffold  51  above the aneurysm sac  14  as shown in  FIG. 6 . 
       FIG. 9  is an illustration of the stent graft system  50  in accordance with an embodiment after the inflatable fill structure  70  has been filled with a hardenable filling medium. According to various embodiments, the hardenable filling medium may include, for example, a liquid polymer that hardens as it is dried or cured, such as a hydrogel or the like. However, the present invention is not limited thereto, and any suitable hardenable filling medium may be used to fill the inflatable fill structure  70 . 
     Referring to  FIG. 9 , in various embodiments, when the inflatable fill structure  70  is inflated or filled, the inner wall  71  of the inflatable fill structure  70  conforms to an outer surface of the body portion  60  down to a portion of an outer surface of the first and second leg portions  82  and  83 , Accordingly, the inflatable fill structure  70  may provide columnar support for the body portion  60  when inflated or filled. Also, when the inflatable fill structure  70  is inflated or filled as shown in the embodiment of  FIG. 9 , the outer wall  72  of the inflatable fill structure  70  expands radially to conform to an inner wall of the aneurysm sac  14  to aid in preventing leaks of blood into the aneurysm sac  14 . 
     With reference to  FIGS. 6, 7, 8, and 9 , by having the body portion  60  be longitudinally extendable and the inflatable fill structure  70  be highly conformable, the body portion  60  can be extended to different lengths and the inflatable fill structure  70  can be conformed to different volumes depending on the dimensions of the aneurysm being treated, which allows for treating a wide range of patients. In such a manner, stent graft systems having a design of the stent graft system  50  can be used in patients with differing aneurysm lengths and volumes, and the body portion  60  can be extended to a length that suits the dimensions of the patient, while the inflatable fill structure  70  can be inflated or filled to a volume that suits the dimensions of the patient. 
       FIGS. 10A, 10B, 10C, 10D, 10E, and 10F  are illustrations showing some steps during placement, extension, and filling of the stent graft system  50  in an infrarenal aneurysm, in accordance with various illustrative embodiments.  FIG. 11  is a flow diagram illustrating a method of using the stent graft system  50  of  FIGS. 10A, 10B, 10C, and 10D , in accordance with an illustrative embodiment. With reference to FIGS,  5 ,  10 A and  11 , in step  200  a catheter  102  containing the stent graft system  50  is advanced over a guidewire  101  through the iliac artery  12  and into the aorta  10 . With reference to  FIGS. 10A, 10B , and  11 , in step  201  the stent graft system  50  is removed from the catheter  102  with the body portion  60  in the telescopically compressed state and the inflatable fill structure  70  in an initial state (e.g., relaxed or unstretched state). The body portion  60  can then radially expand, and the barbs  52  of the radially expandable scaffold  51  penetrate into the wall of the aorta  10  to enhance fixation of the stent graft system  50 . A fill line  79  is also removed from the catheter  102  and is connected to allow a filling medium (e.g., saline, the hardenable filling medium, and/or the like) to be filled into the inflatable fill structure  70 . In various embodiments, the stent graft system  50  also comes in the catheter  102  with a first balloon  111  within the first leg portion  82  and a second balloon  113  within the second leg portion  83 . A first fill line  121  and a second fill line  122  are connected to the first balloon  111  and the second balloon  113 , respectively, to allow for filling and/or unfilling the first balloon  111  and the second balloon  113 . In various embodiments, each of the first balloon  111  and the second balloon  113  may initially be unfilled or partially filled, and may be filled via the first fill line  121  and the second fill line  122 , respectively, after the first leg portion  82  and the second leg portion  83  are pulled into the iliac artery  12  and iliac artery  13 , respectively. 
     In various embodiments, there may be a thread  112  attached to the first balloon  111  and a thread  114  attached to the second balloon  113  as shown in  FIGS. 10B and 10C . The first thread  112  extends through the iliac artery  12 , and the second thread  114  extends through the iliac artery  13 . With reference to  FIGS. 10C and 11 , in step  202  the first thread  112  and the second thread  114  are pulled to pull the first leg portion  82  into the iliac artery  12  and the second leg portion  83  into the iliac artery  13 , respectively, and to cause the body portion  60  to longitudinally extend from the compressed state (as in  FIG. 10B ) to the longitudinally extended state (as in  FIG. 10C ). As the body portion  60  is longitudinally extended, the inflatable fill structure  70  is longitudinally expanded or extended (e.g., stretched or pulled) in an amount corresponding to an amount that the body portion  60  is longitudinally extended (as in  FIG. 10C ). However, the present invention is not limited thereto, and in other embodiments, the first thread  1 . 12  and the second thread  11 . 4  may be omitted. In this case, the first fill line  121  and the second fill line  122  may be pulled to pull the first leg portion  82  into the iliac artery  12  and the second leg portion  83  into the iliac artery  13 . 
     In various other embodiments, such as the embodiment in  FIGS. 10E and 10F , a first wire  116  is connected to the first leg portion  82  and a second wire  118  is connected to the second leg portion  83 . The first wire  116  extends through the iliac artery  12 , and the second wire  118  extends through the iliac artery  13 . In this case, the first wire  116  and the second wire  118  may be pulled to pull the first leg portion  82  into the iliac artery  12  and the second leg portion  83  into iliac artery  13 , respectively, and to cause the body portion  60  to longitudinally extend from the compressed state (as in  FIG. 10E ) to the longitudinally extended state (as in  FIG. 10F ). As the body portion  60  is longitudinally extended, the inflatable fill structure  70  is longitudinally expanded or extended (e.g., stretched or pulled) in an amount corresponding to an amount that the body portion  60  is longitudinally extended (as in  FIG. 10F ). The first wire  116  and second wire  118  can then be detached and removed. 
     Once the first leg portion  82  and the second leg portion  83  are positioned in the iliac artery  12  and the iliac artery  13 , respectively, the first balloon  111  and the second balloon  113  may be filled via the first fill line  121  and the second fill line  122 , respectively, to radially expand the first leg portion  82  and the second leg portion  83 . After filling the first balloon  111  and the second balloon  113 , they can be deflated and removed along with the first fill line  121  and the second fill line  122 . The first balloon  111  and the second balloon  113  may be filled either before the inflatable fill structure  70  is filled, or alter the inflatable fill structure  70  is filled and the fill line  79  is removed therefrom. However, the present invention is not limited thereto, and in other embodiments, the first balloon  111  and the second balloon  113  may be omitted. In this case, each of the first leg portion  82  and the second leg portion  83  may be radially self-expandable to be expanded after being positioned in the iliac artery  12  and the iliac artery  13  via the first wire  116  and the second wire  118 , respectively. 
     With reference to  FIGS. 10D and 11 , in step  203 , the inflatable fill structure  70  of the stent graft system  50  is filled with a hardenable fill medium  74  through the fill line  79 .  FIG. 10D  shows the stent graft system  50  with the inflatable fill structure  70  filled with the hardenable fill medium  74 . In various embodiments, the hardenable fill medium  74  may include, for example, a liquid polymer that hardens as it is dried or cured, such as a hydrogel or the like. However, the present invention is not limited thereto, and any suitable hardenable fill medium may be used to fill the inflatable fill structure  70 . In various embodiments, the inflatable fill structure  70  may first be filled with saline to cause expansion of the inflatable fill structure  70  (e.g., longitudinally and/or radially) with the saline then being removed, and then filled with the hardenable fill medium  74 , but the present invention is not limited thereto. 
     The fill tube  79  and guidewire  101 , as well as the first and second balloons  111  and  113 , the first and second fill lines  121  and  122 , and the first and second threads  112  and  114  (refer to  FIG. 10C ) can then be removed. When the first and second balloons  111  and  113  are filled and/or removed (e.g., via the first and second threads  112  and  114  or the first and second fill lines  121  and  122 ), the first leg portion  82  and the second leg portion  83  radially expand to contact walls of the iliac arteries  12  and  13 , respectively. When inflated or filled as in  FIG. 10D , the inflatable fill structure  70  provides columnar support for the body portion  60  of the stent grail system  50 . 
       FIG. 12  is an illustration of a stem graft system in accordance with another embodiment in a telescopically compressed state, and  FIG. 13  is an illustration of the stent graft system of  FIG. 12  in a longitudinally extended state. In  FIGS. 12 and 13 , the components and elements that are the same or substantially the same as those of the previous embodiments are denoted by like reference numbers, and thus, repeat description may be omitted. 
     Referring to  FIGS. 12 and 13 , the first and second leg portions  182  and  183  of a stent graft system  150  include first and second pleated portions  94  and  96 , respectively. The first pleated portion  94  includes pleated sections  94   a,    94   b,    94   c,    94   d,  and  94   e,  that are divided by pleats  95   a,    95   b,    95   c,  and  95   d,  respectively. The second pleated portion  96  includes pleated sections  96   a,    96   b,    96   c,    96   d,  and  96   e,  that are divided by pleats  97   a,    97   b,    97   c,  and  97   d,  respectively. In the telescopically compressed state, the pleated section  94   b  can fold at least partially up under the pleated section  94   a,  the pleated section  94   c  can fold at least partially up under the pleated section  94   b,  the pleated section  94   d  can fold at least partially up under the pleated section  94   c,  and the pleated section  94   e  can fold at least partially up under the pleated section  94   d.  Similarly, the pleated section  96   b  can fold at least partially up under the pleated section  96   a,  the pleated section  96   c  can fold at least partially up under the pleated section  96   b,  the pleated section  96   d  can fold at least partially up under the pleated section  96   c,  and the pleated section  96   e  can fold at least partially up under the pleated section  96   d.    
     In the compressed state, each of the pleated sections may have a slightly smaller diameter than the above adjacent pleated section so that they can fit within each other in a telescoping manner, and when the pleated sections are extended (e.g., fully or partially) in the longitudinal direction, their diameter may expand radially. In various embodiments, each of the first and second pleated portions  94  and  96  may be formed such that the crown valleys are tucked abluminally, adluminally, or having one end tucked abluminally while the other end is tucked adluminally. is some embodiments, the first and second pleated portions  94  and  96  may have different tucking arrangements from each other. For example, the crown valleys of the first pleated portion  94  may be tucked abluminally, while the crown valleys of the section pleated portion  96  are tucked adluminally, or vice versa. 
       FIG. 14A  illustrates a flowchart of a method in accordance with various embodiments for deploying a stent graft system to repair an aneurysm. In step  300 , the stent graft system is inserted into an aorta with a body portion of the stent graft system in a telescopically compressed state. In step  301 , the body portion of the stent graft system is longitudinally extended from the telescopically compressed state to a longitudinally extended state. In step  302 , an inflatable fill structure surrounding at least a portion of the body portion is filled to provide columnar support for the body portion. 
     In various embodiments, the inflatable fill structure is attached to at least a top of the body portion. In various embodiments, the inflatable fill structure is not attached at a central part of the body portion. In some embodiments, the inflatable fill structure expands in a longitudinal direction as the body portion is extended in the longitudinal direction. Also, in some embodiments, an amount that the inflatable fill structure expands in the longitudinal direction corresponds to an amount that the body portion extends in the longitudinal direction. 
       FIG. 14B  illustrates a method in accordance with an embodiment for longitudinally extending a body portion of a stent graft system. In step  310 , a first leg portion of the stent graft system that is connected to the body portion is pulled into an iliac artery. In step  311 , a second leg portion of the stent graft system that is connected to the body portion is pulled into another iliac artery. In various embodiments, the steps  310  and  311  are performed at a same time. 
       FIG. 14C  illustrates a method in accordance with an embodiment for filling an inflatable fill structure. In step  320 , the inflatable fill structure is filled with saline to expand the inflatable fill structure in a radial direction. In step  321 , the saline is evacuated from the inflatable fill structure. In step  322 , the inflatable fill structure is filled with a hardenable till medium. In various embodiments, the hardenable fill medium comprises a polymer. In various embodiments, the inflatable fill structure is radially expanded to conform to an inner surface of an aorta after being longitudinally extended along with the body portion. 
       FIG. 14D  illustrates a flowchart of a method in accordance with an embodiment that can be used with the method of  FIG. 14A . With reference to  FIG. 14D , in step  330  a first leg portion of the stent graft system is longitudinally extended from a telescopically compressed state to a longitudinally extended state. In step  331 , a second leg portion of the stent graft system is longitudinally extended from a telescopically compressed state to a longitudinally extended state. In various embodiments, the steps  330  and  331  are performed at a same time, In various embodiments, the first leg portion and the second leg portion are connected to the body portion of the stent graft system. 
     According to various embodiments, a stent graft system includes a body portion that is longitudinally extendable from a telescopically compressed state, and includes one or more inflatable fill structures surrounding the body portion. In various embodiments, an inflatable fill structure surrounding the body portion is highly conformal, and may be longitudinally expanded (e.g., stretched or pulled) from an initial state (e.g., rested or unstretched state), as the body portion is longitudinally extended. The amount that the inflatable fill structure is longitudinally expanded may correspond to an amount that the body portion is longitudinally extended. 
     According to various embodiments, the stent graft system may further include a plurality of leg portions connected to the body portion. One or more of the leg portions may be longitudinally extendable from a compressed state. 
     Accordingly, various stent graft systems that can be used in patients with differing aneurysm lengths and volumes have been described. The stent graft systems according to various embodiments can conform to various dimensions of an aneurysm being treated, and thus, allow for treating a wide range of patients. 
       FIG. 15  illustrates a stent graft system  400  in accordance with an embodiment within the aorta  10 . The stent graft system  400  includes a stent graft  420 , a radially expandable scaffold  451 , and an inflatable fill structure  470 . The stent graft  420  includes a body portion  460  with a plurality of pleated sections  462   a,    462   b,    462   c,    462   d,    462   e,    462   f,    462   g  that are configured to be extended from a telescopically compressed state to a longitudinally extended state. The radially expandable scaffold  451  is attached to a top of the body portion  460  and has one or more fixation elements  452 . for penetrating into an aortic wall. The inflatable fill structure  470  is positioned at top section  463  of the body portion  460  and is configured to not expand in a longitudinal direction as the body portion  460  is extended in the longitudinal direction. In various embodiments, the inflatable fill structure  470  is configured to provide a seal at the proximal neck  17  of an aneurysm defined by the aneurysm sac  14 . 
     The stent graft  420  includes the body portion  460  and a bifurcation portion  480 . The bifurcation portion  480  includes a transition portion  481 , a first leg portion  482 , and a second leg portion  483 . The stem graft  420  includes a graft  461 . In various embodiments, the graft  461  is used for the body portion  460  and the bifurcation portion  480 . In some embodiments, one or more other grafts may be used for each of the portions of the stem graft  420 . In various embodiments, the graft  461  is made of a polymer. in some embodiments, the graft  461  is made of expanded Polytetrafluoroethylene (ePTFE). The body portion  460  includes the pleated sections  462   a,    462   b,    462   c,    462   d,    462   e,    462   f,  and  462   g.  Each of the pleated sections  462   a,    462   b,    462   c,    462   d,    462   e,    462   f,  and  462   g  includes a scaffold, respectively, that is encapsulated within or attached to a corresponding portion of the graft  461 . The scaffolds of the pleated sections  462   a,    462   b,    462   c,    462   d,    462   e,    462   f,  and  462   g  may each comprise, for example, a sinusoidal stent frame in a ring shape and may be made from, for example, cobalt-chromium (CoCr) alloy, stainless steel, nitinol, or the like. 
     Each of the pleated sections  462   a,    462   b,    462   c,    462   d,    462   e,    462   f,  and  462   g  ends with a pleat, respectively, in the graft  461 . The pleats in the graft  461  allow for the graft  461  to fold in at those locations, so that the body portion  460  can be telescoping to be in a compressed state, and to allow for movement from the compressed state to the longitudinally extended state. In various embodiments, a length of the body portion  460  in the compressed state may be less than one-fourth of the length of the body portion  460  in the extended state. In various embodiments, a length of the body portion  460  in the compressed state may be less than one-hall of the length of the body portion  460  in the extended state. When extended, the portion of the graft  461  for the body portion  460  is a generally tubular shape that allows for blood flow through a lumen within the body portion  460 . The stent graft system  400  includes the radially expandable scaffold  451  connected to the top of the body portion  460  for providing fixation of the stem graft system  400  in the aorta  10  along an aortic wall. The radially expandable scaffold  451  includes the one or more fixation elements  452  that may, for example, be hooks or barbs for penetrating into an aortic wall and thereby enhancing fixation. In various embodiments, the one or more fixation elements  452  are configured to attach to the aortic wall above the renal arteries  15  and  16 . 
     The transition portion  481  includes a portion of the graft  461  that extends from the body portion  460  to each of the first leg portion  482  and the second leg portion  483 . The transition portion  481  may be made of the same or different material from that of the graft  461 . For example, in various embodiments, the transition portion  481  may be made of, for example, Teflon. In various embodiments, the first leg portion  482  includes radially expandable scaffolds that are encapsulated within or attached to a corresponding portion of the graft  461 . Also, in various embodiments, the second leg portion  483  includes radially expandable scaffolds that are encapsulated within or attached to a corresponding portion of the graft  461 . Each of the first leg portion  482  and the second leg portion  483  is a generally tubular shape that allows for blood flow through a lumen within the first leg portion  482  and the second leg portion  483 , respectively. The stent graft system  400  has a proximal end  491  for receiving blood flow and distal ends  492  and  493  out of which the blood is able to flow. 
     The stein graft system  400  includes the inflatable fill structure  470 . The inflatable fill structure  470  may surround (e.g., entirely surround) the outer circumference of the top section  463  of the body portion  460 , and may be a single inflatable fill structure or a plurality of inflatable fill structures arranged around the body portion  460 . In some embodiments, the inflatable fill structure  470  is located between layers of the graft  461 . In some embodiments, the inflatable fill structure  470  is an endobag or the like. In some embodiments, the inflatable fill structure  470  is attached to the top section  463  of the body portion  460 . In various embodiments, the inflatable fill structure  470  is fillable through a removable fill tube with a hardenable filling material such as Polyethylene glycol (PEG) or another polymer that may be polymerized in situ. 
     The stent graft system  400  is extendable to extend from a telescopically compressed state to a longitudinally extended state in the aorta  10 . In the longitudinally extended state the first leg portion  482  extends into the iliac artery  12  and the second leg portion  483  extends into the iliac artery  13 . In various embodiments, the body portion  460  of the stent graft system  400  is able to be extended and/or expand across the aneurysm sac  14  to exclude the aneurysm sac  14  from aortic blood pressure. The stent graft system  400  includes the body portion  460  that can be placed in the aorta  10 , and the first and second leg portions  482  and  483  extending from the body portion  460  that can be placed into the iliac arteries  12  and  13 , respectively. The inflatable fill structure  470  can be filled to press against a wall of the aorta  10  at the proximal neck  17  to create a proximal seal. The distal ends  492  and  493  of the first and second leg portions  482  and  483  can radially expand against walls of the iliac arteries  12  and  13 , respectively, to form distal seals. 
     The barbs  452  of the radially expandable scaffold  451  can penetrate into the wall of the aorta  10 , thereby enhancing fixation of the stent graft system  400 . Blood is able to flow from the proximal end  491  through the body portion  460  and out of the distal ends  492  arid  493  of the first and second leg portions  482  and  483 , respectively. The inflatable fill structure  470  is initially in an uninflated state, but is tillable with a fill medium. In various embodiments, the inflatable fill structure  470  is located entirely above the pleated sections  462   a,    462   b,    462   c,    462   d,    462   e,    462   f,  and  462   g  of the body portion  460  such that when the pleated sections  462   a,    462   b,    462   c,    462   d,    462   e,    462   f,  and  462   g  of the body portion  460  are pulled from a telescopically compressed state to a longitudinally extended state the inflatable fill structure  470  is not expanded in a longitudinal direction and remains in place. In some embodiments, the inflatable fill structure  470  is filled with a hardenable fill medium to create a seal against the proximal neck  17  prior to the pleated sections  462   a,    462   b,    462   c,    462   d,    462   e,    462   f,  and  462   g  of the body portion  460  being pulled from a telescopically compressed state to a longitudinally extended state. In some embodiments, the inflatable fill structure  470  is filled with a hardenable fill medium to create a seal against the proximal neck  17  after to the pleated sections  462   a,    462   b,    462   c,    462   d,    462   e,    462   f,  and  462   g  of the body portion  460  have been pulled from a telescopically compressed state to a longitudinally extended state. 
     The foregoing description of illustrative embodiments has been presented for purposes of illustration and of description. It is not intended to be exhaustive or limiting with respect to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the disclosed embodiments. Various modifications and changes that come within the meaning and range of equivalency of the claims are intended to be within the scope of the invention. Thus, while certain embodiments of the present invention have been illustrated and described, it is understood by those of ordinary skill in the art that certain modifications and changes can be made to the described embodiments without departing from the spirit and scope of the present invention.