Patent Publication Number: US-9408609-B2

Title: Endograft devices and methods to use the same

Description:
PRIORITY 
     The present application is related to, claims the priority benefit of, and is a U.S. continuation patent application of, U.S. patent application Ser. No. 12/701,340, filed on Feb. 5, 2010 and issued as U.S. Pat. No. 9,050,091 on Jun. 9, 2015, which is related to, claims the priority benefit of, and is a U.S. continuation-in-part patent application of, U.S. patent application Ser. No. 11/997,147, filed Jun. 30, 2008 and issued as U.S. Pat. No. 8,398,703 on Mar. 19, 2013, which is related to, claims the priority benefit of, and is a U.S. national stage entry of, International Patent Application Serial No. PCT/US2006/029424, filed Jul. 28, 2006, which is related to, and claims the priority benefit of, U.S. Provisional Patent Application Ser. No. 60/703,421, filed Jul. 29, 2005. The contents of each of these applications and patents are hereby incorporated by reference in their entirety into this disclosure. 
    
    
     BACKGROUND 
     The present disclosure relates generally to tissue support, including devices and methods for aortic tissue support and for the treatment of aneurysms. 
     Aortic aneurysms are formed in a vessel when the wall of the vessel weakens, either due to disease, aging, heredity or some other process. The pressure of the blood flowing through the weakened area causes the vessel wall to balloon out, forming a blood-filled aneurysm sack. Although most aneurysms begin small, they tend to enlarge over time and the risk of the sack rupturing increases as the aneurysms grows larger. Acute rupture of the aortic aneurysm is a life-threatening event, due to massive internal bleeding with a mortality rate of 75-80%. According to the Society of Vascular Surgeons, ruptured aneurysms account for more than 15,000 deaths in the U.S. each year, making the abdominal aortic aneurysm (AAA) the 13th leading cause of death in the USA. Clearly, early detection and rupture prevention is the key to the final outcome in abdominal aortic aneurysm patient. However, the condition is under-diagnosed because most patients with AAA are asymptomatic. Consequently, the majority of the anomalies are discovered unexpectedly during routine tests or procedures. An estimated 1.7 million Americans have AAA, but only about 250,000-300,000 patients are diagnosed every year. 
     There is no proven medical treatment for AAA, and surgical repair has been the only common therapeutic option. A standard open repair has been associated with significant morbidity and mortality, prolonged recovery, and late complications. Because of these limitations, many patients and their physicians choose to defer operative treatment. Recently, endovascular aneurysm repair (EVAR) has become an alternative and some studies favorably compare endovascular repair with a standard open repair. However, significant concern exists relating to endovascular repair and its value is a subject of healthy debate. Endovascular abdominal aortic aneurysm repair has gained acceptance as a minimally invasive alternative to open surgery in selected patients. While long-term durability remains uncertain, patients and their physicians are willing to accept a degree of uncertainty in exchange for dramatic reduction in duration of hospital stay, and need for blood transfusion. Hence, improvements in the current EVAR devices can potentially make this approach standard for AAA repair. 
     Most patients diagnosed with AAA are not considered for surgery or endovascular repair unless the aneurysm is at least 5 cm in diameter, the point at which the risk of rupture clearly exceeds the risk of repair. Those with a smaller aneurysm are followed closely with regular imaging studies. There has been much speculation over the years about the preventive use of endovascular aneurysm repair in patients with aneurysms smaller than 5 cm, however, vascular surgeons so far have been reluctant to use EVAR for smaller aneurysms due to the concern about the long term durability of the technology and the lack of data demonstrating a clear benefit of early intervention. Moreover, although EVAR outcomes have improved over the years as physicians gain more experience with the procedure, it remains a technically demanding procedure that requires extensive training and this has limited the number of physicians qualified to perform EVAR. 
     Despite the shortcoming relating to training, a number of endovascular devices have been evaluated in clinical trials designed to gain approval from governmental agencies. These devices differ with respect to design features, including modularity, metallic composition and the structure of the stent, thickness, porosity, chemical composition of the polymeric fabric, methods for attaching the fabric to the stent, and presence or absence of an active method of fixing the device to the aortic wall with bars or hooks. With consideration of the numbers of structural variations between different brands of endovascular devices, it would be remarkable if clinical outcome were not equally dissimilar. Parameters such as frequency of endoleak, long-term change in size of the aneurysm sac, reason for device migration and limb thrombosis may be linked to specific device design features. Hence, any improvements in the deployment and attachment of stent graft would increase the utility of EVAR. 
     Important drivers and limiters of EVAR are playing a big role in the decision of the treatment. The drivers include: 1) Less invasive compared to open repair, which translates into shorter hospitalization and recovery and lower major morbidity; 2) Aging of the population will increase the incidence and prevalence of AAA and thoracic aortic aneurysm (TAA); 3) Increasingly informed patient population will generate strong patient demand for minimally invasive therapy, and 4) Next-generation devices, expected to address wider patient population (including those with thoracic disease) and reduce complications relative to current model. The limiters, on the other hand, include the following: 1) Clinical literature does not support prophylactic endovascular treatment of the small aneurysm with a low risk of fracture; 2) High rate of late complication necessitates extensive and potentially life-long post procedural follow-up (not required for open repair) and repeat intervention that makes endovascular therapy potentially more costly than open surgery; 3) Current device is not applicable to full-range of AMA patients; 4) Technical demands of the approach require devices and time-consuming training that may eliminate rapid adoption of new products, particularly for a specialist with a smaller case load, and 5) Surgical conversion is complicated by the presence of the stent graft. Improvements in the current devices would certainly make the drivers outweigh the limiters. 
     The most important trial conducted to date is the EVAR 1 study, which randomized over 1,000 elective patients with aneurysms 5.5 cm or larger comparing EVAR to open surgical repair. Thirty-day mortality published this year demonstrated a clear advantage of EVAR (1.6% vs. 4.7% for open repair). However, EVAR patients had significantly higher rates of secondary intervention (9.8% vs. 5.8%). A second version study, EVAR 2, is comparing EVAR with best medical treatment in patients unsuitable for surgical repair. The 12-month result for EVAR 1 are particularly important, as physicians will be looking to see if endovascular therapy is able, for the first time, to demonstrate significant survival benefit over open surgery after one year. 
     Despite some of its inherent drawbacks, EVAR is expected to experience robust growth over the next several years. The U.S. AAA graft market is projected to increase from $288M in 2004 to $552M in 2008. In addition, contribution from thoracic graft systems, beginning this year, will grow the total US aortic stent market to over $670M in 2008 (Endovascular, 2005). 
     Ongoing areas of concern with endovascular abdominal aortic repair are; 1) Rate of late complications; 2) Appreciable intervention and conversion rates; 3) Dubious cost advantage compared to open surgery due to the need of intervention and regular patient monitoring; 4) Increased device failure with time; 5) Increased procedural failure with time, and 6) Rupture risk of 1% per year after endovascular repair is not dramatically different from the natural history of small 5 cm aneurysms. Hence, there is high rate of secondary intervention (primarily to treat endoleaks—persistent flow within the aneurysm sac that in certain cases can lead to aneurysm rupture, if left untreated), and increasing rate of device failures over time. In addition to endoleaks, other late complications in AAA graft trials include device migration, modular component separation, graft thrombosis, bar separation, and material fatigue. 
     Currently in the U.S., about 60,000 abdominal aortic aneurysm (AAA) patients require intervention each year. The majority of the patients are treated with open surgical repair, while about 40% are treated with EVAR. Although open AAA repair is highly successful, it is also extremely invasive, with an operative mortality rate between 5-10%. Thus, patients with significant co-morbidities are generally not candidates for open repair. These patients are the primary beneficiaries of endovascular grafting or EVAR. EVAR gained tremendous popularity in 1990 after commercial AAA stent graft became available in the U.S. After a one-year period of adjustment, however, problems with the first generation device began to surface including migration, endoleak and endotension. Although physicians remain confident, they have for the most part recovered from the disappointment associated with the first generation technology and are looking forward to future advances in the field. Further expansion of endovascular repair is required to improve the device and good long-term results from large randomized trials comparing EVAR with open surgery. There is no doubt that a device that overcomes some of the current shortcomings of EVAR devices such as migration, endoleak and endotension is greatly welcomed for the treatment of aortic aneurysm. 
     Thus, a need exists in the art for an alternative to the conventional methods of aneurysm treatment. A further need exist for a reliable, accurate and minimally invasive device or technique of treating aneurysms and minimizing their risks of enlarging or rupturing. 
     BRIEF SUMMARY 
     The current EVAR devices and methods are inadequate. They are prone to such fatal problems as migration, endoleak, and endotension. In order to address this medical problem, the present disclosure provides devices and methods for minimizing and/or preventing the growth or rupture of aneurysms or other vascular growth through the use of magnetic tissue support. 
     In at least one embodiment of an endograft assembly of the present disclosure, the endograft assembly comprises an endograft having an inner wall, an outer wall, and a graft structure positioned between the inner wall and the outer wall, the inner wall of the endograft defining an endograft lumen sized and shaped to permit fluid to flow therethrough, and a tube defining one or more tube openings, said tube coupled to the endograft in a configuration whereby the one or more tube openings are exposed along the outer wall of the endograft. In another embodiment, the tube is coupled to the outer wall of the endograft. In yet another embodiment, the tube is coupled to the endograft between the inner wall and the outer wall of the endograft. In an additional embodiment, the endograft further comprises a length, and wherein the tube extends substantially the length of the endograft. 
     In at least one embodiment of an endograft assembly of the present disclosure, the inner wall of the endograft is impermeable to fluids, and wherein the outer wall of the endograft is permeable to fluids. In another embodiment, the endograft assembly further comprises a catheter having a distal catheter end, a proximal catheter end, and defining a lumen therethrough, wherein the distal catheter end of the catheter is configured to be removably coupled to a proximal tube end of the tube. In an additional embodiment, the endograft assembly further comprises a suction/infusion source configured to be coupled to the catheter at or near the proximal catheter end, the suction/infusion source capable of providing suction within the lumen of the catheter and further capable of injecting a substance into the lumen of the catheter. In yet an additional embodiment, the endograft assembly further comprises a suction/infusion source configured to be coupled to the catheter at or near the proximal catheter end, the suction/infusion source capable of providing suction within the lumen of the catheter to facilitate removal of blood present within an aneurysm sac when the endograft assembly is positioned within a vessel at or near the site of a vessel aneurysm and when the catheter is coupled to the tube. 
     In at least one embodiment of an endograft assembly of the present disclosure, the endograft assembly further comprises a suction/infusion source configured to be coupled to the catheter at or near the proximal catheter end, the suction/infusion source capable of injecting a substance into the lumen of the catheter and into an aneurysm sac when the endograft assembly is positioned within a vessel at or near the site of a vessel aneurysm and when the catheter is coupled to the tube. In another embodiment, the substance is capable of forming a cast within the aneurysm sac when it is injected to the aneurysm sac, said cast providing structural reinforcement to the vessel aneurysm. In yet another embodiment, the substance is selected from the group consisting of ethylene vinyl alcohol copolymer, acetate polymer, ethylene vinyl alcohol dissolved in dimethyl sulfoxide, cellulose, cyanoacrylate, glue, and gel magnetic polymer. 
     In at least one embodiment of an endograft assembly of the present disclosure, the endograft comprises a configuration selected from the group consisting of a straight configuration and a curved configuration. In an additional embodiment, wherein the tube comprises a proximal tube end and a distal tube end, and wherein the proximal tube end comprises a tube threaded portion. In yet an additional embodiment, the tube threaded portion corresponds to a catheter threaded portion located at a distal catheter end of a catheter, permitting the catheter to be rotatably coupled to the tube. In another embodiment, the catheter further comprises a catheter tip at the distal catheter end, the catheter tip configured to fit within a lumen of the tube. In at least one embodiment of an endograft assembly of the present disclosure, the tube comprises a proximal tube end and a distal tube end, and wherein the proximal tube end comprises one or more unidirectional valves. In another embodiment, the one or more unidirectional valves permit fluid to flow out of the tube when a catheter is coupled thereto, and wherein the one or more unidirectional valves prevents fluid from flowing out of the tube when the catheter is not coupled thereto. In yet another embodiment, the endograft assembly comprises one or more materials selected from the group consisting of nitinol, plastic, polyurethane, silastic, polyvinylchloride, and polytetrafluoroethylene. 
     In at least one embodiment of an endograft assembly of the present disclosure, the graft structure of the endograft assembly is capable of a first, collapsed configuration, and is further capable of a second, expanded configuration. In an additional embodiment, the graft structure is selected from the group consisting of a traditional stent, a balloon-expandable device, or an autoexpandable device. In yet an additional embodiment, the inner wall comprises a fluid-impermeable fabric, and wherein the outer wall comprises a fluid-permeable fabric. In another embodiment, the endograft assembly further comprises a sponge sheath having a distal end and a proximal end, the sponge sheath coupled to the outer wall of the endograft and configured to permit blood flow therethrough. In yet another embodiment, the sponge sheath defines one or more sponge channels therein, said sponge channels configured to permit fluid flow therethrough. 
     In at least one embodiment of an endograft assembly of the present disclosure, the endograft assembly comprises an endograft having an inner wall and an outer wall, and a graft structure positioned between the inner wall and the outer wall, the inner wall of the endograft defining an endograft lumen sized and shaped to permit fluid to flow therethrough, a tube comprising a proximal tube end, a distal tube end, one or more unidirectional valves at or near the proximal tube end, and one or more tube openings defined along the tube, said tube coupled to the endograft in a configuration whereby the one or more tube openings are exposed along the outer wall of the endograft, a catheter having a distal catheter end, a proximal catheter end, and defining a lumen therethrough, wherein the distal catheter end of the catheter is configured to be removably coupled to a proximal tube end of the tube, and a suction/infusion source configured to be coupled to the catheter at or near the proximal catheter end, the suction/infusion source capable of providing suction within the lumen of the catheter and further capable of injecting a substance into the lumen of the catheter. 
     In at least one embodiment of method for using an endograft assembly of the present disclosure, the method comprising the steps of delivering an endograft assembly within a vessel of a patient at or near the site of a vessel aneurysm, the endograft assembly comprising an endograft, a tube coupled to the endograft, the tube defining one or more tube openings, a catheter removably coupled to the tube, and a suction/infusion source coupled to the catheter, operating a suction/infusion source to remove blood present within an aneurysm sac of the vessel aneurysm, and operating the suction/infusion source to inject a substance into the aneurysm sac to form a cast at or near the site of the vessel aneurysm. In another embodiment, the step of delivering the endograft assembly further comprises the step of deploying the endograft assembly within the vessel. In yet another embodiment, the step of operating a suction/infusion source to remove blood present within an aneurysm sac causes a wall of the vessel aneurysm to collapse toward the endograft assembly. In an additional embodiment, the substance is capable of forming a cast within the aneurysm sac when it is injected to the aneurysm sac, said cast providing structural reinforcement to the vessel aneurysm. 
     In at least one embodiment of an endograft assembly of the present disclosure, the endograft assembly comprises an endograft having an inner wall and an outer wall, and a graft structure positioned between the inner wall and the outer wall, the inner wall of the endograft defining an endograft lumen sized and shaped to permit fluid to flow therethrough, and a sponge sheath having a distal end and a proximal end, the sponge sheath coupled to the outer wall of the endograft and configured to permit blood flow therethrough. In another embodiment, the inner wall of the endograft is impermeable to fluids, and wherein the outer wall of the endograft is permeable to fluids. In yet another embodiment, the sponge sheath defines one or more sponge channels therein, said sponge channels configured to permit fluid flow therethrough. 
     In at least one embodiment of an endograft assembly of the present disclosure, the endograft assembly further comprises a reservoir bag coupled to the sponge sheath at or near the proximal end of the sponge sheath, said reservoir bag capable of receiving fluid from the sponge sheath and the one or more sponge channels. In another embodiment, the endograft assembly further comprises a catheter having a distal catheter end, a proximal catheter end, and defining a lumen therethrough, wherein the distal catheter end of the catheter is configured to be removably coupled to the reservoir bag. In yet another embodiment, the endograft assembly further comprises a suction/infusion source configured to be coupled to the catheter at or near the proximal catheter end, the suction/infusion source capable of providing suction within the lumen of the catheter and further capable of injecting a substance into the lumen of the catheter. In an additional embodiment, the endograft assembly further comprises a suction/infusion source configured to be coupled to the catheter at or near the proximal catheter end, the suction/infusion source capable of providing suction within the lumen of the catheter to facilitate removal of blood present within an aneurysm sac when the endograft assembly is positioned within a vessel at or near the site of a vessel aneurysm and when the catheter is coupled to the reservoir bag. 
     In at least one embodiment of an endograft assembly of the present disclosure, the endograft assembly further comprises a suction/infusion source configured to be coupled to the catheter at or near the proximal catheter end, the suction/infusion source capable of injecting a substance into the lumen of the catheter and into an aneurysm sac when the endograft assembly is positioned within a vessel at or near the site of a vessel aneurysm and when the catheter is coupled to the reservoir bag. In another embodiment, the substance is capable of forming a cast within the aneurysm sac when it is injected to the aneurysm sac, said cast providing structural reinforcement to the vessel aneurysm. In yet another embodiment, the substance is selected from the group consisting of ethylene vinyl alcohol copolymer, acetate polymer, ethylene vinyl alcohol dissolved in dimethyl sulfoxide, cellulose, cyanoacrylate, glue, and gel magnetic polymer. 
     In at least one embodiment of an endograft assembly of the present disclosure, the endograft comprises a configuration selected from the group consisting of a straight configuration and a curved configuration. In another embodiment, the reservoir bag comprises a reservoir bag threaded portion. In yet another embodiment, the reservoir bag threaded portion corresponds to a catheter threaded portion located at a distal catheter end of a catheter, permitting the catheter to be rotatably coupled to the reservoir bag. In an additional embodiment, the catheter further comprises a catheter tip at the distal catheter end, the catheter tip configured to fit within a lumen of the reservoir bag. 
     In at least one embodiment of an endograft assembly of the present disclosure, the reservoir bag comprises one or more unidirectional valves. In an additional embodiment, the one or more unidirectional valves permit fluid to flow out of the reservoir bag when a catheter is coupled thereto, and wherein the one or more unidirectional valves prevents fluid from flowing out of the reservoir bag when the catheter is not coupled thereto. In yet an additional embodiment, the endograft assembly comprises one or more materials selected from the group consisting of plastic, polyurethane, silastic, polyvinylchloride, and polytetrafluoroethylene. In another embodiment, the endograft assembly is capable of a first, collapsed configuration, and wherein the endograft assembly is capable of a second, expanded configuration. In yet another embodiment, the sponge sheath comprises one or more materials selected from the group consisting of cellulose fiber, wood fiber, foamed plastic polymer, polyurethane, silastic, rubber, polytetrafluoroethylene, synthetic sponge, natural sponge, low-density polyether, polyvinyl alcohol, and polyester. 
     In at least one embodiment of an endograft assembly of the present disclosure, the endograft assembly comprises an endograft having an inner wall and an outer wall, and a graft structure positioned between the inner wall and the outer wall, the inner wall of the endograft defining an endograft lumen sized and shaped to permit fluid to flow therethrough, a sponge sheath having a distal end and a proximal end, the sponge sheath coupled to the outer wall of the endograft and configured to permit blood flow therethrough, the sponge sheath defining one or more sponge channels configured to permit fluid flow therethrough, a reservoir bag coupled to the sponge sheath at or near the proximal end of the sponge sheath, said reservoir bag capable of receiving fluid from the sponge sheath and the one or more sponge channels, a catheter having a distal catheter end, a proximal catheter end, and defining a lumen therethrough, wherein the distal catheter end of the catheter is configured to be removably coupled to the reservoir bag, and a suction/infusion source configured to be coupled to the catheter at or near the proximal catheter end, the suction/infusion source capable of providing suction within the lumen of the catheter and further capable of injecting a substance into the lumen of the catheter. 
     In at least one embodiment of a method for using an endograft assembly of the present disclosure, the method comprises the steps of delivering an endograft assembly within a vessel of a patient at or near the site of a vessel aneurysm, the endograft assembly comprising an endograft, a sponge sheath coupled to the endograft, the sponge sheath defining one or more sponge channels, a reservoir bag coupled to the sponge sheath, said reservoir bag capable of receiving fluid from the sponge sheath and the one or more sponge channels, a catheter removably coupled to the reservoir bag, and a suction/infusion source coupled to the catheter, operating a suction/infusion source to remove blood present within an aneurysm sac of the vessel aneurysm, and operating the suction/infusion source to inject a substance into the aneurysm sac to form a cast at or near the site of the vessel aneurysm. In another embodiment, the step of delivering the endograft assembly further comprises the step of deploying the endograft assembly within the vessel. In yet another embodiment, the step of operating a suction/infusion source to remove blood present within an aneurysm sac causes a wall of the vessel aneurysm to collapse toward the endograft assembly. In an additional embodiment, the substance is capable of forming a cast within the aneurysm sac when it is injected to the aneurysm sac, said cast providing structural reinforcement to the vessel aneurysm. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a front view of a magnetically stabilized luminal stent graft assembly with two magnetic bodies according to an exemplary embodiment of the present disclosure; 
         FIG. 2  shows an angled view of a luminal stent graft with a magnetic covering and powder according to an exemplary embodiment of the present disclosure; 
         FIG. 3A  shows a front view of a luminal stent graft embedded with magnetic beads or particles surrounded by a stabilizing magnetic body to prevent distension of the aneurysmic region according to an exemplary embodiment of the present disclosure; 
         FIG. 3B  shows a cross-section of  FIG. 3A  to emphasize axial support of the diseased region; 
         FIG. 4  shows T 11  changes with a maximum of T 11 =42,826 KPa θ=0° and 180° in the inner circular) and minimum of T 11 =−42.826 KPa (θ=90° and 270° in the inner circular) according to an exemplary embodiment of the present disclosure; 
         FIG. 5  shows a front view of a luminal stent graft within an aneurysm incorporating a perforated tube for controlling the fluid environment within the aneurysm and an optional pressure sensor as part of a telemetry system according to an exemplary embodiment of the present disclosure; 
         FIGS. 6A-6D  show endograft assemblies according to exemplary embodiments of the present disclosure; 
         FIG. 6E  shows a block diagram of various components of an endograft assembly according to an exemplary embodiment of the present disclosure; 
         FIG. 7  shows a diagram of a method for using an endograft assembly according to an exemplary embodiment of the present disclosure; 
         FIGS. 8A-8C  show an endograft assembly positioned within a bodily vessel according to an exemplary embodiment of the present disclosure; 
         FIGS. 9A-9C  show a connection and disconnection of a removable catheter and a tube of an endograft assembly according to an exemplary embodiment of the present disclosure; 
         FIG. 10  shows an endograft assembly comprising a sponge sheath according to an exemplary embodiment of the present disclosure; 
         FIGS. 11A-12B  show portions of endograft assemblies comprising a sponge sheath according to exemplary embodiments of the present disclosure; 
         FIGS. 13A-13C  show a connection and disconnection of a removable catheter and a reservoir bag of an endograft assembly according to an exemplary embodiment of the present disclosure; 
         FIG. 14  shows a diagram of a method for using an endograft assembly according to an exemplary embodiment of the present disclosure; and 
         FIGS. 15A and 15B  show an endograft assembly positioned within a bodily vessel according to an exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure of the present application provides various endograft devices and methods for using the same. For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of this disclosure is thereby intended. 
     As discussed briefly above, the aneurysm size appears to be the one of the most important factors determining risk of aneurysm rupture. Changes in aneurysm dimension have been used as a surrogate marker for clinical efficacy after endovascular repair. Other morphological changes, including progressive angulation, and aortic neck enlargement, may occur in response to either aneurysm exclusion or associated degenerative changes in adjacent segments, respectively. In endovascular repair, the aneurysm sac is left intact and, as a consequence, this feature plays an important role in outcome assessment, defining the success or failure of aneurysm exclusion. Long term aneurysm exclusion and device stabilization is dependent on the maintenance of an effective attachment, connection, or seal between the endograft and the host aorta. Therefore dilatation of the aorta at the site or sites intended for primary endograft fixation may lead to treatment failure either with device migration or via the occurrence of a new endoleak with aneurysm expansion. The use of magnets as described in the present disclosure is intended to reduce the neck enlargement and remodeling since the magnet will distribute the stress more uniformly unlike the stent that pose stress concentration which induce vascular remodeling. 
     Endoleak is defined by the persistence of blood flow outside the lumen of the endoluminal graft but within the aneurysm sac, as determined by an imaging study. An endoleak is evidence of incomplete exclusion of the aneurysm from the circulation and may be the result of an incomplete seal between the endograft and the blood vessel wall, an inadequate connection between components of a modular prosthesis, fabric defects or porosity, or retrograde blood flow from patent aortic side branches. Hence, an adhesive force at the neck of the stent may minimize or prevent endoleak (type I). 
     Endoleaks, including their detection, potential clinical significance, and treatment remain an active area of investigation. However, although it is now evident that an endoleak may resolve spontaneously, a proportion of those that do persist have been associated with late aneurysm rupture. Endoleaks classification include:
         1. Type I:
           a) Inadequate seal at the proximal end of endograft   b) Inadequate seal at the distal end of endograft   c) Inadequate seal at the iliac occluder plug   
           2. Type II: Flow from visceral vessels (lumbar, IMA, accessory renal, Hypogastric) without attachment site connection.   3. Type III:
           a) Flow from module disconnection   b) Flow from fabric disruption (Minor&lt;2 mm, Major&gt;2 mm)   
           4. Type IV: Flow from porous fabric (&lt;30 days after graft placement)       

     There are also endoleaks of undefined origins where flow is visualized but the source is unidentified. 
     Endotension. It is now appreciated as AAA may continue to enlarge after endovascular repair, even in the absence of detectable endoleak, and that this enlargement may lead to aneurysm rupture. Explanation for persistence or recurrent pressurization of an aneurysm sac includes blood flow that is below the sensitivity limits for detection with current imaging technology, or pressure transmission through thrombus, or endograft fabric. On physical examination, the aneurysm may be pulsatile and intrasac measurements may reveal pressure that approach or equal to systemic values. A magnetic device according to the present disclosure that provides sufficient “seal” at the two necks of the aneurysm and along the body of the aneurysm would eliminate endoleaks type I and II. 
     Migration. Migration is defined by clinical and radiographic parameters, as a caudal movement of the proximal attachment site or cranial movement of a distal attachment site. A device is considered to have migrated if at least 10 mm of movement was noted relative to anatomic landmarks, a patient experiences a symptom from migration, irrespective of distance, or a secondary intervention was undertaken to remedy migration-related problems, irrespective of distance. An adhesive force with sufficient shear component would also eliminate migration. Hence, one of the advantages of the present disclosure is the development of a magnet-based anchoring device at the two ends of the graft that overcomes endoleak and migration. 
     In biomedical engineering, the electromagnetic effect on biological cells has diverse applications such as MRI, bypass surgery, and MEMS-related devices. Static and time-dependent fields are used in the diagnosis and treatment of human disease. MRI involves using a large magnetic field to image structure. The therapeutic benefits of low frequency magnetic fields have been shown to induce gene expression and upregulate the heat shock protein. Recently, magnets are advocated for use in vascular coupling for distal anastomosis in bypass surgery, which has lead to a multi-center clinical trial. To date, most of the magneto-static research on biological cells is investigated by using analytic or numerical finite difference methods. 
     The fundamental equations governing the interaction between current and magnetic-flux density can be found in any classic textbook. In general, those equations are complex due to the fact that matter possesses a great variety of properties. For example, if the body of interest is elastic, then a change of shape, volume and temperature can appear. Also, if the sum of all forces acting on the body is not zero, translational or rotational acceleration may occur. Therefore, it is important to calculate the Magnetostatic forces and couple the Magnetostatic forces with other physical effects in order to determine the deformation, rotation, displacement and so on in the matter. In the present application, the force balance including the Maxwell&#39;s force is analyzed and simulated based on the distribution of the magnetic-flux density. The coupled formulation of the magnetic field and the surface stress balance for treatment of aortic aneurysm is demonstrated. 
     In general, the magnetic field intensity is not curl-free and, therefore, we cannot describe magnetic field intensity in terms of a scalar function. However, there are a number of important applications in magnetics in which a magnetic field exists, but there are no current densities involved. The most obvious are those involving permanent magnets. Here we consider a concentric annulus of the stent graft internal to the vessel lumen and the permanent magnetic ring external to the vessel wall as shown in  FIG. 1 . Since the magnetic ring does not cover the entire circumference of the vessel (covers 0 to 270°), the solution must be numerical. To design the geometry and magnetic properties of the two poles of the magnet (stent and magnetic ring) to produce the necessary Maxwell force acting on the aortic tissue that prevents migration, and endoleak. 
     A three-dimensional Laplace&#39;s equation describes the solution for the potential field in cylindrical coordinates (p, Φ, z) 
     
       
         
           
             
               
                 
                   
                     
                       
                         
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                         ) 
                       
                       ⁢ 
                       R 
                     
                   
                   = 
                   0 
                 
               
               
                 
                   ( 
                   
                     3 
                     ⁢ 
                     c 
                   
                   ) 
                 
               
             
           
         
       
     
     The solutions of the first two equations are elementary:
 
 Z ( z )= e   ±kz   (4a)
 
 Q (φ)= e   ±νφ   (4b)
 
     The radial equation can be put in a standard form by the change of variable x=kρ. Then it becomes 
     
       
         
           
             
               
                 
                   
                     
                       
                         
                           ⅆ 
                           2 
                         
                         ⁢ 
                         R 
                       
                       
                         ⅆ 
                         
                           x 
                           2 
                         
                       
                     
                     + 
                     
                       
                         1 
                         x 
                       
                       ⁢ 
                       
                         
                           ⅆ 
                           R 
                         
                         
                           ⅆ 
                           x 
                         
                       
                     
                     + 
                     
                       
                         ( 
                         
                           1 
                           - 
                           
                             
                               v 
                               2 
                             
                             
                               x 
                               2 
                             
                           
                         
                         ) 
                       
                       ⁢ 
                       R 
                     
                   
                   = 
                   0 
                 
               
               
                 
                   ( 
                   5 
                   ) 
                 
               
             
           
         
       
     
     This is Bessel&#39;s equation, and the solutions are called Bessel functions of order ν. When ν=m is an integer and k is a constant to be determined. The radial factor is
 
 R (ρ)= CJ   m ( k ρ)+ DN   m ( k ρ)  (6)
 
Finally, we get
 
Φ(ρ,φ, z )=( Ae   ±kz )( Be   ±νφ )[ CJ   m ( k ρ)+ DN   m ( k ρ)]  (7)
 
where A, B, and C are the unknown constant. If we combine equation (7) and boundary conditions, we can solve any type of magnetic field between the partial (0° to 270°) concentric annulus.
 
     When the distribution of the magnetic field is known, the Maxwell&#39;s stress tensor can be calculated by the following formulation after the coordinate system transformation from the cylindrical coordinate to the rectangular coordinate. 
                       T   ij     =       1   μ     ⁡     [         B   i     ⁢     B   j       -       1   2     ⁢     B   2     ⁢     δ   ij         ]         ⁢     
     ⁢     (       Maxwell   &#39;     ⁢   s   ⁢           ⁢   Stress   ⁢           ⁢   Tensor     )             (   8   )               
where T ij : Maxwell&#39;s stress tensor [N/M 2 , Newton/square meter); δ ij : Kronecker delta; B j : magnetic-flux density T, Tesla or Wb/m 2 , weber/meter 2 ]; H i =μB i ; magnetic field intensity [N/(A·m), weber/(ampere·meter)]; δ ij =1 if i=j; δ ij =0 if i≠j.
 
     In Matrix form, 
     
       
         
           
             
               
                 
                   
                     
                       T 
                       ij 
                     
                     = 
                     
                       [ 
                       
                         
                           
                             
                               
                                 μ 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 
                                   H 
                                   x 
                                   2 
                                 
                               
                               - 
                               
                                 
                                   1 
                                   2 
                                 
                                 ⁢ 
                                 μ 
                                 ⁢ 
                                 
                                   
                                      
                                     H 
                                      
                                   
                                   2 
                                 
                               
                             
                           
                           
                             
                               μ 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               
                                 H 
                                 x 
                               
                               ⁢ 
                               
                                 H 
                                 y 
                               
                             
                           
                           
                             
                               μ 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               
                                 H 
                                 x 
                               
                               ⁢ 
                               
                                 H 
                                 z 
                               
                             
                           
                         
                         
                           
                             
                               μ 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               
                                 H 
                                 x 
                               
                               ⁢ 
                               
                                 H 
                                 y 
                               
                             
                           
                           
                             
                               
                                 μ 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 
                                   H 
                                   y 
                                   2 
                                 
                               
                               - 
                               
                                 
                                   1 
                                   2 
                                 
                                 ⁢ 
                                 μ 
                                 ⁢ 
                                 
                                   
                                      
                                     H 
                                      
                                   
                                   2 
                                 
                               
                             
                           
                           
                             
                               μ 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               
                                 H 
                                 y 
                               
                               ⁢ 
                               
                                 H 
                                 z 
                               
                             
                           
                         
                         
                           
                             
                               μ 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               
                                 H 
                                 x 
                               
                               ⁢ 
                               
                                 H 
                                 z 
                               
                             
                           
                           
                             
                               μ 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               
                                 H 
                                 y 
                               
                               ⁢ 
                               
                                 H 
                                 z 
                               
                             
                           
                           
                             
                               
                                 μ 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 
                                   H 
                                   z 
                                   2 
                                 
                               
                               - 
                               
                                 
                                   1 
                                   2 
                                 
                                 ⁢ 
                                 μ 
                                 ⁢ 
                                 
                                   
                                      
                                     H 
                                      
                                   
                                   2 
                                 
                               
                             
                           
                         
                       
                       ] 
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     ( 
                     
                       
                         Maxwell 
                         &#39; 
                       
                       ⁢ 
                       s 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       Stress 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       Tensor 
                     
                     ) 
                   
                 
               
               
                 
                   ( 
                   9 
                   ) 
                 
               
             
           
         
       
     
     Once the Maxwell&#39;s stress tensor is computed, the equilibrium force balance in the surface layer of the artery may be presented. 
     (Equilibrium Equation for Static Case)
 
σ ji,j   +T   ji,j   +f   i =0  (10)
 
where σ ji  is the stress tensor [N/M 2 , Newton/square meter] and f i  is the force [N/M 3 , Newton/cubic meter].
 
     Once the Maxwell stress is computed, we must calculate the Maxwell force. Elementary theory relates magnetostatic forces to changes in the total magnetic field energy when infinitesimal virtual displacements are made between magnetic elements. 
     
       
         
           
             
               
                 
                   F 
                   = 
                   
                     
                       ∂ 
                       
                         ∂ 
                         R 
                       
                     
                     ⁢ 
                     
                       ∫ 
                       
                         
                           
                             B 
                             · 
                             H 
                           
                           2 
                         
                         ⁢ 
                         
                           ⅆ 
                           v 
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   11 
                   ) 
                 
               
             
           
         
       
     
     An alternative method using the Maxwell Stress Tensor allows magnetostatic forces to be calculated directly without approximating the limit of a virtual displacement. Instead, integration of the stress tensor T ij  over any surface enclosing the object will give the net force acting on it directly if we assume that the permeability of the surrounding tissue (vessel wall and blood) is significantly different than that of the permanent magnets. If n is the outward normal to the surface, the Maxwell force may be computed as follows:
 
 F=∫T   ij   ·nds   (12)
 
     Expanding the dot product T ij ·n allows the force integral equation (12) to be written explicitly as 
     
       
         
           
             
               
                 
                   F 
                   = 
                   
                     
                       
                         1 
                         
                           μ 
                           0 
                         
                       
                       ⁢ 
                       
                         ∮ 
                         
                           
                             [ 
                             
                               
                                 
                                   B 
                                   · 
                                   n 
                                 
                                 ⁢ 
                                 
                                   ) 
                                 
                                 ⁢ 
                                 B 
                               
                               - 
                               
                                 
                                   1 
                                   2 
                                 
                                 ⁢ 
                                 
                                   B 
                                   2 
                                 
                                 ⁢ 
                                 n 
                               
                             
                             ] 
                           
                           ⁢ 
                           
                             ⅆ 
                             s 
                           
                         
                       
                     
                     = 
                     
                       
                         μ 
                         0 
                       
                       ⁢ 
                       
                         ∮ 
                         
                           
                             [ 
                             
                               
                                 
                                   H 
                                   · 
                                   n 
                                 
                                 ⁢ 
                                 
                                   ) 
                                 
                                 ⁢ 
                                 H 
                               
                               - 
                               
                                 
                                   1 
                                   2 
                                 
                                 ⁢ 
                                 
                                   H 
                                   2 
                                 
                                 ⁢ 
                                 n 
                               
                             
                             ] 
                           
                           ⁢ 
                           
                             ⅆ 
                             s 
                           
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   13 
                   ) 
                 
               
             
           
         
       
     
     The stress vector 
                   P   =       μ   0     ⁡     [         H   ·   n     ⁢     )     ⁢   H     -       1   2     ⁢     H   2     ⁢   n       ]               (   14   )               
does not generally point along H. However for the two extreme cases of the H field either normal or parallel to the surface, the forces are either attractive or repulsive across the surface. But when the field crosses the surface at any other angle than 0° or 90°, there will be a shear component to the force which acts in the plane of the surface. When 3-D axis migration occurs, the magnetic fields H will change so that the axis force will be created in order to prevent the migration. This requires numerical method such as the FEM simulation.
 
     An exemplary embodiment of the present disclosure as used in graft assembly  100  is shown in  FIG. 1 . Assembly  100  includes magnetic bodies  110  and magnetic polymer graft  111 . In this embodiment, the magnetic bodies  110  may be situated at the proximal and distal ends of magnetic polymer graft  111  which may be positioned distal to the renal arteries  123  and proximal to the common iliac arteries  122  as shown in  FIG. 1 . The magnetic bodies  110  may cover part or the entire circumference of the abdominal aorta  120 . The magnetic bodies  110  are shown to be ring-shaped in  FIG. 1 , but they can be any other shape (e.g., staple-shaped, etc.) as long as they are able to provide a sufficient magnetic attractive force on the magnetic polymer graft  111  to stabilize the magnetic polymer graft  111  on the inner surface of the aorta  120 . 
     The magnetic polymer graft  111  may be situated inside the abdominal aorta  120  or the aneurysmic sac  121  and the magnetic bodies  110  may be situated external to the wall of the abdominal aorta  120  or the aneurysmic sac  121  as shown in  FIG. 1 . The magnetic bodies  110  may be composed of a material such that they produce a high magnetic field with a low mass and should be stable against demagnetization. When a ferromagnetic material is magnetized in one direction, it will not relax back to zero magnetization when the imposed magnetizing field is removed. The amount of magnetization it retains at zero driving field is defined as remanence. The amount of reverse driving field required to demagnetize it is called coercivity. Some compositions of ferromagnetic material will retain an imposed magnetization indefinitely and are useful as permanent magnets. NdFeB (Neodymium Iron Boron) is an example of a permanent magnet used in biological applications including sutureless vascular anastomosis with magnets. 
     The magnetic bodies  110  may stabilize the magnetic polymer graft  111  at the proximal and distal ends of the magnetic polymer graft  111  thereby preventing movement of the magnetic polymer graft  111  or endoleak or endotension. The magnetic polymer graft  111  may be uniformly composed of a metallic material commonly used in the medical arts such that the magnetic bodies  110  may exert an attractive force on the metallic material such that the magnetic polymer graft  111  is held in position by the magnetic bodies  110  on the proximal and distal ends of the magnetic polymer graft  1 I as illustrated in  FIG. 1 . Alternatively, the magnetic polymer graft  111  may be composed of metallic material only at its proximal and distal ends such that the magnetic bodies  110  may be properly positioned to exert an attractive force on these proximal and distal ends of magnetic polymer graft  111 . In this variation, the body of the magnetic polymer graft  111  may be mesh-like and may be composed of any material commonly used in the medical stenting arts (e.g., polytetrafluoroethylene—PTFE) such that it can house the metallic material at its proximal and distal ends. The magnetic polymer graft  111  may act as a stent by providing a structural passageway for blood to flow down the abdominal aorta  120  while avoiding contact with the aneurysmic sac  121 . 
     A number of different delivery methods may be used to introduce the magnetic bodies  110  in place. Such methods are also applicable to the other exemplary embodiments presented below. Various delivery methods include, but are not limited to: (a) an abdominal laparoscopic procedure (AAA) or thoracoscopic procedure (TAA); (b) a minimal surgical procedure; or (c) an open surgical procedure. Other methods and procedures are apparent to one having ordinary skill in the art after consideration of the present exemplary embodiments and are, thus, within the scope of the present disclosure. 
     Another exemplary embodiment of the present disclosure is presented as assembly  200  and is shown in  FIG. 2 . Assembly  200  depicts a magnetic polymer graft  211  which includes a magnet cover  212 , bonded magnet powder  213 , and a graft lumen  214 . The bonded magnet powder  213  of the magnetic polymer graft  211  may be composed of any material commonly used in the medical magnetic arts. The graft lumen  214  may be formed using materials commonly used in the medical stent arts (e.g., polytetrafluoroethylene—PTFE). The graft lumen  214  may allow blood to pass through its material and thereby prevent contact with the aneurysm (not shown) and it may be of such a diameter as to achieve the optimal or desired volume of blood flow through the aneurysm. 
     The magnetic polymer graft  211  may interact with magnetic bodies (not shown) situated on the external wall of the abdominal aorta or aortic aneurysm (not shown). In this way, the magnetic polymer graft  213  can be held in place by the attractive force being exerted on it by the magnetic bodies (not shown). Thus, the bonded magnet powder  213  can be situated inside a magnet cover  212  which may be the external layer of the magnetic polymer graft  211 . The magnet cover  212  may act to protect and confine the magnet powder  213  and further serve to make contact with the inside of the abdominal aorta or aortic aneurysm. This configuration would provide the bonded magnetic powder  213  maximum communication with the magnetic bodies (not shown) situated on the external wall of the abdominal aorta or aortic aneurysm. The magnetic polymer graft  211  may be inserted through endovascular procedure into the patient thereby avoiding the complications associated with other invasive techniques. 
     Yet another exemplary embodiment of the present disclosure as shown in graft assembly  300  is presented in  FIG. 3A . Assembly  300  includes magnetic body  310  and magnetic polymer graft  311 . The magnetic body  310  is depicted as being ring-shaped in  FIG. 3A  but it may be any other shape as described above. The magnetic body  310  may cover part or the entire circumferential surface of the abdominal aorta  320 . In the latter case, the magnetic body  310  may partially ensheathe the abdominal aorta  320  such that the magnetic body  310  is provided with enough surface area to interact with the magnetic polymer graft  311  on the inside of the abdominal aorta  320  thereby allowing a sufficient magnetic force to be applied to the magnetic polymer graft  311 . The directional arrows  351  illustrate the manner in which the magnetic body  310  may ensheathe the abdominal aorta  320  (e.g., circumferentially) to allow for optimal interaction between the magnetic body  310  and the magnetic polymer graft  311 . 
       FIG. 3B  shows a cross-section of assembly  300 . The lumen  352  of the graft  311  may provide a conduit for the blood to flow through the aneurysmic sac (not shown) such that the blood flow does not contact the aneurysmic sac (not shown). The outer surface of the abdominal aorta  320  may be in physical contact with the magnetic body  310  as illustrated in  FIG. 3B . The magnetic polymer graft  311  may make physical contact with the inner surface of the abdominal aorta  320  such that the magnetic polymer graft  311  is fitted tightly enough against the inner surface of the abdominal aorta  320  in order to prevent blood leakage out of the graft  311  and into the aneurysmic sac (not shown) via space between the proximal portion of the graft  311  and the inner surface of the abdominal aorta  320 . This particular embodiment may also prevent endoleak type II and may further incorporate magnetic beads or particles  363  along the body of graft composite as shown in  FIG. 3B . Application of magnetic body  310  external to the abdominal aorta  320  in the form of gel or glue on the adventitial surface may also provide a restrictive force which will prevent expansion of aorta against endoleak type II or endotension. 
     In this embodiment, we may consider the magnetic flux density B, which plays the significant role in the computation of attraction forces. The magnetic polymer graft  311  may include, for examples polymer-bonded Nd—Fe—B magnets (BNP-8) by compression moulding (polymer-bonding: magnet powders are mixed with a polymer carrier matrix, such as epoxy). The magnetic bodies  310  are formed in a certain shape, when the carrier is solidified, which has residual induction Br (0.6-0.65 Teslas or 6000-6500 Gauss); the ring consists of, for example, Heusler alloy (Fe 80 B 20 ), which has the saturation magnetic flux density of 0.1257 Teslas (=1257 Gauss); or consists of carbon-coated metal particles, which has saturation magnetization exceeding about 120 emu/g (saturation magnetic flux density equal to or approximately 0.15 Teslas). The properties provide sufficient force to support the abdominal aorta  320 . 
     An exemplary measurement of the stress tension exerted on the blood vessel and the changes in T 11  (Maxwell&#39;s stress tensor wherein i=1 and j=1) are shown in  FIG. 4  according to an exemplary embodiment of the present disclosure. The maximum stress tension is exerted on the vessel at  401  and  403  while the minimum stress tension is exerted on the vessel at  402  and  404  when an exemplary embodiment of the present disclosure is used to stabilize the graft to the inside wall of the vessel by placing magnetic bodies on the external surface of the vessel. This calculation demonstrates that the stress levels are within biologically acceptable ranges. In other words, the stress distribution demonstrates that the computed Maxwell stresses are well within the physiological range of tissue stress and should not harm the tissue. Hence, the present disclosure does not overly perturb the vessel wall and should not induce an injury response or remodeling. 
     Another embodiment of the present disclosure comprises a graft assembly  500  as shown in  FIG. 5 . An exemplary assembly  500 , as shown in  FIG. 5 , includes magnetic bodies  510 , magnetic polymer graft  511 , tube  515  with tube openings  516 , a catheter  517 , and an optional pressure sensor  518 . Tube  515  with tube openings  516  may function to suck or siphon out accumulated blood and/or other tissue or matter and to collapse the wall of aneurysmic sac  521  to decrease blood-clot volume, which may reduce the stress in aneurysmic sac  521  after deployment of magnetic bodies  510  and decrease the risk of aneurysmic rupture. 
     Catheter  517  may be connected to tube  515  from the femoral artery such that a user is able to suction out accumulated blood and/or other matter. Alternatively, tube  515  and tube openings  516  may function as an embolization device such that a biocompatible liquid polymer (e.g., ethylene vinyl alcohol copolymer, cellulose, acetate polymer, cyanoacrylates or glue gel magnetic powder, or the like) may be introduced into aneurysmic sac  521  via catheter  517  and through tube openings  516  in order to pack aneurysmic sac  521  and thereby reduce the possibility of endoleak or endotension. 
     Tube  515  may be situated as shown in  FIG. 5  on the outer surface of magnetic polymer graft  511  in a coiled configuration. Tube  515  may have tube openings  516  situated on the length of tube  515 , and may be spaced apart and of such a diameter so that tube openings  516  may optimally function as described above. Additionally, tube openings  516  may be a slit or any other geometric shape including, but not limited to, a pyramid, in order to maximize the functioning of tube openings  516  as previously described. 
     In order to ensure efficient deployment of magnetic polymer graft  511  and magnetic bodies  510  (e.g., tight seal at the distal and proximal ends), it would be desirable to measure pressure in aneurysmic sac  521 . An optional pressure sensor  518  may be situated on the outer surface of magnetic polymer graft  511  via mounting or gluing. Optional pressure sensor  518  may be in communication with an external telemetry monitoring system (not shown) via a wireless communication system (not shown). Optional pressure sensor  518  may be used to indicate whether or not a successful deployment of magnetic polymer graft  511  has been achieved. In this case, the measured pressure will yield a pulsatile tracing initially before deployment of magnetic bodies  510  and magnetic polymer graft  511 . Once magnetic bodies  511  secure the proximal and distal ends of aneurysmic sac  521 , a tight seal between magnetic bodies  510  and the surface of aneurysmic sac  521  would eliminate the pulsatile tracing. This would provide indication of successful deployment. This can equally apply to the current art of stent grafts without magnets. 
     Optional pressure sensor  518  may also be used to monitor the patient&#39;s aneurysm by measuring the pressure within aneurysmic sac  521 . It may monitor the interior pressure of aneurysmic sac  521  by measuring the local pressure outside of the wall of magnetic polymer graft  511  and inside the outstretched wall of aneurysmic sac  521 . This would be of tremendous clinical value as the physician can monitor the status of aneurysmic sac  521  and adapt treatment according to aneurysmic behavior. Currently, expensive and complicated imaging methods (such as MRI and CT) are used to monitor the dimension of the aneurysm longitudinally at discreet times (annually, etc.). Pressure is more relevant mechanically as a predictor of rupture and with telemetry it can be monitored continuously. 
     An additional embodiment of an endograft assembly of the present disclosure is shown in  FIG. 6A . As shown in  FIG. 6A , endograft assembly  600  comprises an endograft  602  having an inner wall  604 , an outer wall  606 , and a graft structure  603  positioned therebetween. Graft structure  603 , in at least one embodiment, may be mesh-like and may be composed of any material commonly used in the medical stenting arts (e.g., various polymers and metals, including but not limited to PTFE). Graft structure  603 , in various embodiments, may comprise a traditional stent, a balloon-expandable device, or an autoexpandable device. Inner wall  604  and outer wall  606  may comprise a fabric as described herein, or may comprise one or more other materials capable of permitting or prohibiting fluid flow therethrough as referenced herein. Inner wall  604  and outer wall  606  may be positioned a distance from one another, to permit graft structure  603  to be positioned therebetween, and further to permit a tube  515  having tube openings  516  to be positioned therebetween. 
     Inner wall  604  also defines an endograft lumen  605 , as shown in  FIG. 6A , permitting blood flow through a vessel when endograft assembly  600  is positioned therein. Tube openings  516  within tube  515  are effectively exposed along the outer wall  606  of endograft  602 , whereby, for example, tube  515  has a sealed portion for passing from the walls of endograft  602  into a space outside of endograft  602 . In another exemplary embodiment, tube  515  is incorporated into outer wall  606  so that tube openings  516  of tube  515  are exposed along the outer wall  606 . In at least one embodiment, inner wall  604  is impermeable to fluids (i.e., blood), and outer wall  606  is permeable to fluids, including blood. Endograft  602  may comprise any number of additional features that typically or occasionally accompany endografts. 
     As shown in  FIG. 6A , the proximal end  608  of tube  515  may be removably coupled to a distal end  610  of removable catheter  612 . A suction/infusion source (not shown) may be coupled to the removable catheter  612  at or near the distal end  610  of removable catheter  612 , so that fluid present in, for example, an aneurysm sac, may be removed by applying suction to or within removable catheter  612  so that the fluid may enter tube openings  516  of tube  515  as described herein. 
     Additional embodiments of endograft assemblies  600  of the present disclosure are shown in  FIGS. 6B-6D . In  FIG. 6B , an exemplary endograft assembly  600  is shown in a collapsed configuration to permit, for example, insertion of endograft assembly  600  into a vessel.  FIG. 6C  shows an exemplary embodiment of an endograft assembly  600  of the present disclosure in an open or deployed configuration so that endograft assembly  600  may be used within the body as referenced herein. In at least one embodiment, endograft assembly  600  may be opened or deployed by way of moving/pulling a portion of endograft assembly  600  relative to another portion, similar to the deployment of a stent, so that graft structure  603  of endograft  602  may expand from a collapsed configuration. In at least this example, tube  515  is incorporated into or positioned upon outer wall  606 , so that tube openings  516  of tube  515  are exposed along the outer wall  606  of endograft  602 . Such an exemplary endograft assembly  600  may be useful in connection with, for example, treating an abdominal aortic aneurysm. In addition, and as shown in  FIG. 6C , removable catheter  612  is coupled to tube  515 , with a sealed entrance of tube  515  through the outer wall  606  of endograft assembly  600 . 
     Another exemplary embodiment of an endograft assembly  600  of the present disclosure is shown in  FIG. 6D . As shown in  FIG. 6D , the exemplary endograft assembly  600  comprises a curved configuration, which may be useful to treat, for example, a thoracic aortic aneurysm. An exemplary embodiment of an endograft assembly  600  of the present disclosure is shown in  FIG. 6E  as a block diagram with identified functional components, wherein said system comprises, for example, an endograft  602  comprising a graft structure  603 , a tube  515 , a removable catheter  612 , and a suction/infusion source  614  (such as, for example, a syringe). 
     An exemplary endograft assembly  600 , including the endograft assembly  600  shown in  FIG. 6A , may be used by performing the following method. Steps of an exemplary method  700  for deploying and using an endograft assembly  600  of the present disclosure are shown in  FIG. 7 . As shown in  FIG. 7 , method  700  may comprise the step of delivering an endograft assembly  600  to a desired site within a body, including, but not limited to, an aneurysm sac (an exemplary delivery step  702 ). This step may be performed using any number of methods for delivering endografts, stents, and/or other implantable devices within a human body, so long as removable catheter  612  either remains affixed to tube  515  or is ultimately connected to tube  515 , so that a suction/infusion source  614  coupled to removable catheter  612  may be used as referenced herein. After endograft assembly  600  is positioned within a vessel, graft portion  603  of endograft assembly  600  may be opened/deployed from a closed/collapsed configuration (an exemplary deployment step  704 ) to secure endograft assembly  600  within said vessel. 
     After endograft assembly  600  is deployed within the vessel, suction from a suction/infusion source  614  may be used (an exemplary suction step  706 ) to withdraw, for example, blood, blood clots, and/or other particulates from an aneurysm sac, by way of blood and/or other materials entering tube openings  516  of tube  515  present within/about endograft assembly  600 . Performance of suction step  706  may also cause the walls of aneurysm sac to collapse about endograft assembly  600 . The degree to which said walls may collapse about endograft assembly  600  depends on the relative thickness of said sac/vessel walls. 
     After removal of fluid from the area of interest, suction/infusion source  614  may be used to inject a substance (an exemplary injection step  708 ) into, for example, the aneurysm sac. Such a substance may comprise any number of biocompatible liquids including, but not limited to, various polymers such as ethylene vinyl alcohol (EVOH) copolymer, acetate polymer, EVOH dissolved in dimethyl sulfoxide (DMSO), cellulose, various cyanoacrylates (such as 2-octyl cyanoacrylate, n-butyl cyanoacrylate, iso-butyl-cyanoacrylate, and/or methyl-2- or ethyl-2-cyanoacrylate, for example), various glues/(such as fibrin glues, ultraviolet-light-curable glues, collagen-based glues, and/or resorcinol-formaldehyde glues, for example), various sealants (such as albumin based sealants and/or hydrogel sealants—eosin based primer having a copolymer of polyethylene glycol with acrylate end caps with a sealant of polyethylene glycol plus polylactic acid, for example), gel magnetic polymer, gelatin-resorcinol-formaldehyde, styrene-derivatized (styrenated) gelatin, poly(ethylene glycol)diacrylate (PEGDA), polylactic-co-glycolic acid) (PLGA), carboxylated camphorquinone in phosphate-buffered saline (PBS), polymethylmethacrylate, vascular endothelial growth factor, fibroblast growth factor, hepatocyte growth factor, connective tissue growth factor, placenta-derived growth factor, and/or angiopoietin-1 or granulocyte-macrophage colony-stimulating factor, for example. 
     Injection of such substances into the aneurysm sac would be performed to strengthen/reinforce the weakened aneurysm sac walls (forming a rigid or semi-flexible cast) to reduce the likelihood of or prevent aneurysm rupture, which can be fatal in many instances. Said substances may also prevent the migration of an endograft assembly  600  within the vessel by adhering to said assembly  600 . 
     After all suction and injection steps have been performed, removable catheter  612  would be disconnected from tube  515  (an exemplary catheter disconnection step  710 ) so that the endograft assembly  600  would be separate from removable catheter  612 . Removable catheter  612  may then be withdrawn from the patient&#39;s body (an exemplary catheter withdrawal step  712 ), allowing the endograft assembly  600 , with substance  806  (as shown in  FIG. 8C , for example) positioned external to assembly  600  to reinforce weakened aneurysm sac walls, to remain within the body. 
     An exemplary embodiment of an endograft assembly  600  of the present disclosure is shown in  FIGS. 8A-8C . As shown in  FIG. 8A , endograft assembly  600  has been inserted, positioned, and deployed within vessel  800  at a site of an aneurysm sac  802 , which is presumably filled with blood, blood clots, and/or other particulates. The application of suction via removable catheter  612  by way of a suction/infusion source (not shown) operates to remove the blood, blood clots, and/or other particulates, allowing the distended vessel wall  804  to collapse or revert back to a relatively native configuration as shown in  FIG. 8B . Reinforcement of the vessel wall  804  at the site of aneurysm may be performed by injection step  708  of the method described herein, whereby a substance  806  is injected using suction/infusion source through removable catheter  612 , through tube  515 , and out of tube openings  516  into the space surrounding endograft assembly  600  at the site of aneurysm.  FIG. 8C  depicts this procedure, with the black dots representing injected substance  806 . 
       FIGS. 9A-9C  show exemplary embodiments of a portion of an endograft assembly  600  and at least one embodiment of connecting and disconnecting a tube  515  of endograft assembly  600  to/from removable catheter  612  (also referred to as an intra-stent graft connection). As shown in  FIG. 9A , an exemplary embodiment of a removable catheter  612  may comprise a catheter tip  900  configured to fit within the internal lumen  902  of tube  515 . Removable catheter  612 , in at least one embodiment, may comprise a first threaded portion  904  at or near the distal end  610  of removable catheter  612 , said first threaded portion  904  corresponding to a second threaded portion  906  within tube  515  at or near the proximal end  608  of tube  515 . Tube  515 , in an exemplary embodiment, may comprise one or more unidirectional valves  908 , said valves  908  permitting fluid to flow in and out of tube  515  while removable catheter  612  is coupled thereto (and when unidirectional valves  908  are in a first, open configuration), but preventing fluid from flowing out of tube  515  when removable catheter  612  is disconnected from tube  515  (and when unidirectional valves  908  are in a second, closed configuration) as shown in  FIG. 9C . Furthermore, and when unidirectional valves  908  are closed, blood from the vessel to which endograft assembly  600  is positioned is prevented from exiting tube  515 . 
     Removal of removable catheter  612  from tube  515  may be performed as shown in  FIG. 9B . As shown in  FIG. 9B , removable catheter  612  may be rotated in a direction indicated by the arrow shown in the figure (or rotated in an opposite direction depending on the configuration of the first threaded portion  904  and the second threaded portion  906 ), whereby said rotation would allow removable catheter  612  to detach from tube  515 , in the direction of the arrow shown in  FIG. 9C , permitting removal of removable catheter  612  from the body (at, for example, a patient&#39;s femoral artery). Rotation of removable catheter  612 , as well as operation of suction/infusion source  614  as referenced herein, may be performed by a user external to a patient&#39;s body. 
     Additional embodiments of mechanisms for connecting and disconnecting tube  515  from removable catheter  612  are also contemplated by the present disclosure. Such mechanisms may include, but are not limited to, pulling removable catheter  612  with enough force to detach removable catheter  612  from tube  515 , magnetic coupling of removable catheter  612  to tube  515 , and other mechanisms known in the art for connecting and disconnecting two tubes. 
     An additional embodiment of an endograft assembly  600  of the disclosure of the present application is shown in  FIG. 10 . As shown in  FIG. 10 , endograft assembly  600  comprises an endograft  602  having an inner wall  604 , an outer wall  606 , a graft structure  603  positioned therebetween, and further comprising a sponge sheath  1000  positioned around at least a portion of the outer wall  606  of endograft  602 . Inner wall  604  defines an endograft lumen  605 , as shown in  FIG. 10 , permitting blood flow through a vessel when endograft assembly  600  is positioned therein. In at least one embodiment, inner wall  604  is impermeable to fluids (i.e., blood), and outer wall  606  is permeable to fluids, including blood. Sponge sheath  1000  may comprise any number of biocompatible spongy (porous) materials including, but not limited to, cellulose/wood fibers, various foamed plastic polymers, polyurethane, silastic, rubber, PTFE, synthetic sponges, natural sponges, low-density polyether (also known as the rainbow packs of non-absorbent sponges), polyvinyl alcohol (PVA), and polyester. Sponge sheath  1000 , in at least one embodiment, is positioned circumferentially around the outer wall  606  of endograft  602 , but does not cover either end of said endograft  602 . 
     In at least one embodiment, and as shown in the exemplary embodiment of the endograft assembly  600  shown in  FIG. 10 , one or more sponge channels  1002  are defined within sponge sheath  1000 . Sponge channels  1002  may, as shown in the exemplary embodiment shown in  FIG. 10 , have open distal ends  1004  at or near the distal end  1006  of endograft  602 , and the proximal ends  1008  of sponge channels  1002 , at or near the proximal end of endograft  602 , are in fluid communication with a reservoir bag  1010  coupled to sponge sheath  1000 . Sponge channels  1002  may be parallel to one another (as shown in  FIG. 10 ), or may comprise a perpendicular, radial, or net configuration. Reservoir bag  1010  may be collapsible, and may comprise any number of materials as referenced herein in connection with various endograft assemblies and/or components. 
     Additional embodiments of exemplary endograft assemblies  600  (and portions thereof) of the present disclosure are shown in  FIGS. 11A-11C . As shown in  FIG. 11A , an exemplary endograft assembly  600  comprises an endograft  602  comprising a graft structure  603 , a sponge sheath  1000  (identified by the numerous ovals to visually depict the pores of a sponge), and a reservoir bag  1010  coupled thereto. The endograft assembly  600  shown in  FIG. 11A  is shown in a collapsed configuration to permit, for example, insertion of endograft assembly  600  into a vessel.  FIG. 11B  shows an exemplary embodiment of an endograft assembly  600  of the present disclosure in an open or deployed configuration so that endograft assembly  600  may be used within the body as referenced herein. The exemplary endograft assembly is also shown in  FIG. 11B  with a removable catheter  612  removably coupled to reservoir bag  1010 , so that blood removed from the aneurysm cavity from sponge sheath  1000  that enters reservoir bag  1010  may be removed using removable catheter  612 . 
     A portion of an exemplary endograft assembly  600  of the present disclosure is shown in  FIG. 11C . As shown in the portion of endograft assembly  600  shown in  FIG. 11C , endograft assembly  600  comprises an endograft  602  comprising a graft structure  603 , a sponge sheath  1000 , and sponge channels  1002  having distal ends  1004  at the distal end  1006  of endograft  602 . 
     Additional embodiments of portions of exemplary endograft assemblies  600  of the present disclosure are shown in  FIGS. 12A and 12B . As shown in  FIG. 12A , endograft assembly  600  comprises an endograft  602  surrounded by a sponge sheath  1000 . At the distal end of endograft  602 , sponge channels  1004  are visible within sponge sheath  1000  as shown in  FIG. 11C .  FIG. 12B  shows a portion of an exemplary endograft assembly  600 , whereby a reservoir bag  1010  is coupled to a sponge sheath  1000  at or near the proximal end  1200  of endograft assembly  600 . A removable catheter  612  is also shown in  FIG. 12B  coupled to reservoir bag  1010 . Removable catheter  612  may be removably coupled to reservoir bag  1010  in the same or similar manner as removable catheter  612  is coupled to tube  515  as shown in  FIGS. 9A-9C , or removable catheter  612  may be removably coupled to reservoir bag  1010  as referenced below. 
       FIGS. 13A-13C  show exemplary embodiments of a portion of an endograft assembly  600  and at least one embodiment of connecting and disconnecting a reservoir bag  1010  of endograft assembly  600  to/from removable catheter  612 . As shown in  FIG. 13A , an exemplary embodiment of a removable catheter  612  comprises a catheter tip  900  configured to fit within the internal space  1300  of reservoir bag  1010 . Removable catheter  612 , in at least one embodiment, may comprise a first threaded portion  904  at or near the distal end  610  of removable catheter  612 , said first threaded portion  904  corresponding to a second threaded portion  1302  within reservoir bag  1010 . Reservoir bag  1010 , in an exemplary embodiment, may comprise one or more unidirectional valves  1304 , said valves  1304  permitting fluid to flow in and out of reservoir bag  1010  while removable catheter  612  is coupled thereto (and when unidirectional valves  1304  are in a first, open configuration), but preventing fluid from flowing out of reservoir bag  1010  when removable catheter  612  is disconnected from reservoir bag  1010  (and when unidirectional valves  1304  are in a second, closed configuration) as shown in  FIG. 13C . Furthermore, and when unidirectional valves  1304  are closed, blood from the vessel to which endograft assembly  600  is positioned is prevented from exiting reservoir bag  1010 . In addition, and as shown in  FIGS. 13A-13C , a stent graft wall  1306  may be positioned at or near the portion of reservoir bag  1010  to receive removable catheter  612 , whereby stent graft wall  1306  provides reinforcement so that reservoir bag  1010  does not collapse about removable catheter  612 . 
     Removal of removable catheter  612  from reservoir bag  1010  may be performed as shown in  FIG. 13B . As shown in  FIG. 13B , removable catheter  612  may be rotated in a direction indicated by the arrow shown in the figure (or rotated in an opposite direction depending on the configuration of the first threaded portion  904  and the second threaded portion  1302 ), whereby said rotation would allow removable catheter  612  to detach from reservoir bag  1010 , in the direction of the arrow shown in  FIG. 13C , permitting removal of removable catheter  612  from the body (at, for example, a patient&#39;s femoral artery). Rotation of removable catheter  612 , as well as operation of suction/infusion source  614  as referenced herein, may be performed by a user external to a patient&#39;s body. 
     Additional embodiments of mechanisms for connecting and disconnecting reservoir bag  1010  from removable catheter  612  are also contemplated by the present disclosure. Such mechanisms may include, but are not limited to, pulling removable catheter  612  with enough force to detach removable catheter  612  from reservoir bag  1010 , magnetic coupling of removable catheter  612  to reservoir bag  1010 , and other mechanisms known in the art for connecting and disconnecting a tube from a reservoir. 
     An exemplary endograft assembly  600 , including the endograft assemblies  600  shown in  FIGS. 10-13C , may be used by performing the following exemplary method  1400  for deploying and using an endograft assembly  600  of the present disclosure shown in  FIG. 14 . As shown in  FIG. 14 , method  1400  may comprise the step of delivering endograft assembly  600  to a desired site within a body, including, but not limited, an aneurysm sac (an exemplary delivery step  1402 ). This step may be performed using any number of methods for delivering endografts, stents, and/or other implantable devices within a body known in the art, so long as removable catheter  612  remains affixed to reservoir bag  1010  or is ultimately connected to reservoir bag  1010 , so that a suction/infusion source  614  coupled to removable catheter  612  may be used as referenced herein. After endograft assembly  600  is positioned within a vessel, graft portion  603  of endograft assembly  600  may be opened/deployed from a closed/collapsed configuration (an exemplary deployment step  1404 ) to secure endograft assembly  600  within said vessel. 
     After endograft assembly  600  is deployed within a vessel, suction from a suction/infusion source  614  may be used (an exemplary suction step  1406 ) to withdraw, for example, blood, blood clots, and/or other particulates from an aneurysm sac, by way of blood entering sponge channels  1002  of sponge sheath  1000  present around endograft assembly  600 , entering reservoir bag  1010 , and exiting out of removable catheter  612 . Performance of suction step  1406  may also cause the walls of aneurysm sac to collapse about endograft assembly  600 , which depends on the relative thickness of said sac/vessel walls. 
     After removal of fluid from the area of interest, suction/infusion source  614  may be used to inject a substance (an exemplary injection step  1408 ) into, for example, the aneurysm sac. Such a substance may comprise any number of biocompatible liquids including, but not limited to, various polymers such as ethylene vinyl alcohol (EVOH) copolymer, acetate polymer, EVOH dissolved in dimethyl sulfoxide (DMSO), cellulose, cyanoacrylates, various glues, and gel magnetic polymer. Injection of such substances from removable catheter  612 , through sponge sheath  1000 , and into the aneurysm sac would be performed to strengthen/reinforce the already weakened aneurysm sac walls (forming a cast) to reduce or prevent the likelihood of aneurysm rupture, which can be fatal in many instances. Said substances may also prevent the migration of an endograft assembly  600  within the vessel by adhering to said assembly  600 . 
     After all suction and injection steps have been performed, removable catheter  612  would be disconnected from reservoir bag  1010  (an exemplary catheter disconnection step  1410 ) so that the endograft assembly  600  would be separate from removable catheter  612 . Removable catheter  612  may then be withdrawn from the patient&#39;s body (an exemplary catheter withdrawal step  1412 ), allowing the endograft assembly  600 , with a substance  806  positioned external to assembly  600  to reinforce weakened aneurysm sac walls, to remain within the body. 
     Use of an exemplary endograft assembly  600  consistent with method  1400  is shown in  FIGS. 15A and 15B . As shown in  FIG. 15A , endograft assembly  600  is positioned within a vessel  800  at the site of an aneurysm (identified by aneurysm sac  802  and distended vessel wall  804 ). Upon removal of blood from aneurysm sac  802  (via suction step  1406 , for example) through sponge sheath  1000 , into reservoir bag  1010 , and out from removable catheter  612 , one or more substances  806  may be injected into aneurysm sac  802  as shown in  FIG. 15B  (via injection step  1408 , for example). The injected substance  806  (represented by the black dots in  FIG. 15B ) may form a cast as referenced herein, reinforcing the vessel walls  804  at the site of an aneurysm. 
     Several advantages to such an exemplary endograft assembly  600  include the following. First, the collapsible sponge sheath  1000  of endograft assembly  600 , positioned closely to the external surface of endograft  602 , may vary its volume according to the size of its pores and may occupy some or all of the aneurysm sac cavity. The pores within sponge sheath  1000  may facilitate the removal of blood content from the aneurysm sac cavity to enter sponge sheath  1000 , thus collapsing the aneurysm sac wall about endograft assembly  600 . The combination of sponge sheath  1000  (with its inherent pores) and sponge channels  1002  allow relatively easy removal of blood from the aneurysm sac and the injection of substances into the aneurysm sac with low resistance. Furthermore, the collapsible sponge sheath  1000  may be useful for all EVAR endoprosthesis procedures in order to form a cast around the endograft assembly  600 , filling the aneurysm sac, and avoiding many complications such as migration, endoleak, and structural alterations of endograft  602  produced by the stress-stretching pressure wall effect. 
     The various endograft assemblies  600 , as well as components coupled thereto, may comprise any number of suitable medical grade materials, including, but not limited to, nitinol, various plastics, polyurethane, silastic, polyvinylchloride (PVC), and polytetrafluoroethylene (PTFE). 
     As shown in the various embodiments of endograft assemblies  600  of the present disclosure, said assemblies  600  are configured to permit blood flow through the vessel for which they are placed. Said endograft systems  600  also have the additional advantage of being used in all EVAR endoprosthesis procedures in order to perform a cast around the endograft assembly  600 , filling the aneurysm sac and avoiding several complications such as Endoleak I and II and structural alterations of the endograft assembly  600  produced by the stress stretching pressure wall effect. 
     Endograft assemblies  600  of the present disclosure may be delivered and/or positioned within a vessel lumen using any number of medical tools known in the art to deliver stents and/or endografts. 
     Although the above exemplary embodiments of the present disclosure are described in connection with treatment of aneurysms, particularly an abdominal aortic aneurysm, the disclosure of the present application is not limited to its use in correcting aneurysms. Many other uses are possible within the scope of the present disclosure. For example, the combination of a metallic material and a corresponding magnetic device may be used for the correction of the structure or architecture of organs, such as the heart or along other parts of the aorta or other vessel. 
     While various embodiments of devices and methods for treating aneurysms have been described in considerable detail herein, the embodiments are merely offered by way of non-limiting examples of the disclosure described herein. It will therefore be understood that various changes and modifications may be made, and equivalents may be substituted for elements thereof, without departing from the scope of the disclosure. Indeed, this disclosure is not intended to be exhaustive or to limit the scope of the disclosure. 
     Further, in describing representative embodiments, the disclosure may have presented a method and/or process as a particular sequence of steps. However, to the extent that the method or process does not rely on the particular order of steps set forth herein, the method or process should not be limited to the particular sequence of steps described. Other sequences of steps may be possible. Therefore, the particular order of the steps disclosed herein should not be construed as limitations of the present disclosure. In addition, disclosure directed to a method and/or process should not be limited to the performance of their steps in the order written. Such sequences may be varied and still remain within the scope of the present disclosure.