extension into the descending aorta are often ideal candidates. studies have reported successful use of hybrid techniques for treating kommerell diverticulum and descending aneurysms in patients with previous coarctation repairs. in addition, hybrid techniques combining both open and endovascular repair are also used in managing emergency complications in the aortic arch, such as retrograde ascending dissection and endoleaks from previous stent grafting of descending aorta. a "reverse frozen elephant trunk repair" is shown to be particularly effective. adjunctive procedures snorkel: a covered stent placed into a visceral vessel adjacent to the main body of the evar device. the aortic lumen of the visceral stent is directed superiorly, resembling a snorkel. chimney: in tevar, a covered stent placed from the ascending aorta to a great vessel (e.g., innominate artery) and adjacent to the main body of the evar is termed a chimney. in anatomic position, blood flows superiorly through a chimney-stent graft into the great vessel, just as smoke flows up a chimney. periscope: like a snorkel, a periscope stent graft provides flow to a visceral vessel, but in a retrograde fashion, with the aortic lumen inferior to the main body of the evar device. stents: large bare-metal stents have been used to treat proximal endoleaks, as have aortic extension cuffs to treat endograft migration. glue: trans-catheter embolic glue has been used to treat type i endoleaks, with inconsistent success. endoanchors: small, helically shaped devices are screwed through the endograft and into the aortic wall. endoanchors have been used successfully to treat endoleaks and, in concert with an aortic extension endograft, to treat migration of the original endograft. rigorous evaluations and long-term outcomes of this technique are not yet available. risks the complications of evar can be divided into those that are related to the repair procedure and those related to the endograft device. for example, a myocardial infarction that occurs immediately after the repair is normally related to the procedure and not the device. by contrast, the development of an endoleak from degeneration of endograft fabric would be a device-related complication. durability and problems such as 'endoleaks' may require careful surveillance and adjuvant procedures to ensure the success of the evar or evar/hybrid procedure. ct angiography (cta) imaging has, in particular, made a key contribution to planning, success, durability in this complex area of vascular surgery. a major cause of complications in evar is the failure of the seal between the proximal, infra-renal aneurysm neck and the endovascular graft. risk of this form of failure is especially elevated in adverse or challenging proximal neck anatomies, where this seal could be compromised by unsuitable geometric fit between the graft and vessel wall, as well as instability of the anatomy. new recent techniques have been introduced to address these risks by utilizing a segment of the supra-renal portion of the aorta to increase the sealing zone, such as with fenestrated evar, chimneys and snorkels. these techniques may be suitable in certain patients with qualifying factors, e.g., configuration of renal arteries, renal function. however, these are more complex procedures than standard evar and may be subject to further complications. an approach that directly augments the fixation and sealing between the graft and aorta to mimic the stability of a surgical anastomosis is endoanchoring. endoanchors are small, helically shaped implants that directly lock the graft to the aortic wall with the goal to prevent complications of the seal, especially in adverse neck anatomies. these endoanchors may also be used to treat identified leaks between the graft and proximal neck. procedure-related arterial dissection, contrast-induced kidney failure, thromboembolizaton, ischemic colitis, groin hematoma, wound infection, type ii endoleaks, myocardial infarction, congestive heart failure, cardiac arrhythmias, respiratory failure. device-related endograft migration, aneurysm rupture, graft limb stenosis/kinking, type i/iii/iv endoleaks, stent graft thrombosis, or infection. endoleaks an endoleak is a leak into the aneurysm sac after endovascular repair. five types of endoleaks exist: type i - perigraft leakage at proximal or distal graft attachment sites (near the renal and iliac arteries) type ii - retrograde flow to the aneurysm sac from branches such as the lumbar and inferior mesenteric arteries. type ii endoleaks are the most common, and least serious type of endoleak. type ii endoleaks do not require immediate treatment, as a portion will resolve spontaneously. type iii - leakage between overlapping parts of the stent (i.e., the connection between overlapping components) or rupture through graft material. type iv - leakage through the graft wall due to the quality (porosity) of the graft material. as seen in first-generation grafts, changes in graft material in modern devices have decreased the prevalence of type iv leaks. type v - expansion of the aneurysm sac without an identifiable leak. also called "endotension". type i and iii leaks are considered high-pressure leaks and are more concerning than other leak types. depending on the aortic anatomy, they may require further intervention to treat. type 2 leaks are common and often can be left untreated unless the aneurysm sac continues to expand after evar. spinal cord injury spinal cord injury is a devastating complication after aortic surgery, specifically for thoracoabdominal aortic aneurysm repair; severe injury could lead to urine and fecal incontinence, paresthesia and even paraplegia. the risk varies between studies with two metanalysis demonstrating a pooled incidence of spinal cord injury 2.2% and 11%. predictive factors include increasing extent of coverage, hypogastric artery occlusion, prior aortic repair and perioperative hypotension. spinal cord injury related to aortic repair occurs due to impaired blood flow to the spine after coverage of blood vessels, important to the blood circulation of the spine, namely intercostal- and lumbar arteries. a few methods exist for potentially reversing spinal cord injury, if it arises, elevated blood pressure, increased oxygenation, blood transfusion and cerebrospinal fluid drainage. cerebrospinal fluid drainage cerebrospinal fluid drainage is one of the adjunct methods used to reverse spinal cord injury. with increased drainage of spinal fluid, the intrathecal pressure decreases which allows for increase blood perfusion to the spine, possibly reversing the ischemic injury of the spinal tissue due to lessened blood supply. the benefits of this procedure have been established in open aortic repair and suggested in endovascular aortic repair. recovery after evar unlike traditional aortic repair, standard recovery after evar is remarkably straightforward. patients who have undergone evar typically spend one night in the hospital to be monitored, although it has been suggested that evar can be performed as a same-day procedure. patients are advised to slowly return to normal activity. there are no specific activity restrictions after evar, however, patients typically are seen by their surgeon within one month after evar to begin post-evar surveillance. there is limited research looking at patients' experience of recovery after more complex and staged evar for thoracoabdominal aortic diseases. one qualitative study found that patients with complex aortic diseases struggle with physical and psychological setbacks, continuing years after their operations. history dr. juan c. parodi introduced the minimally-invasive endovascular aneurysm repair (evar) to the world and performed the first successful endovascular repair of an abdominal aortic aneurysm on 7 september 1990 in buenos aires on a friend of carlos menem, the then president of argentina. the first device was simple, according to parodi: "it was a graft i designed with expandable ends, the extra-large palmaz stent, a teflon sheath with a valve, a wire, and the valvuloplasty balloon, which i took from the cardiologists." parodi's first patient lived for nine years after the procedure and died from pancreatic cancer. the first evar performed in the united states was in 1992 by drs. frank veith, michael marin, juan parodi and claudio schonholz at montefiore medical center affiliated with albert einstein college of medicine. the modern endovascular device used to repair abdominal aortic aneurysms, which is bifurcated and modular, was pioneered and first employed by dr. timothy chuter while a fellow at the university of rochester. the first clinical series of his device was published from nottingham in 1994. the first endovascular repair of a ruptured abdominal aortic aneurysm was also reported from nottingham in 1994. by 2003, four devices were on the market in the united states. each of these devices has since been either abandoned or further refined to improve its characteristics in vivo. special populations women women are known to have smaller aortas on average than men, so are potential candidates for aaa treatment at smaller maximum aneurysm diameters than men. transplant candidates as immunosuppressive medications are known to increase the rate of aneurysm growth, transplant candidates are aaa repair candidates at smaller maximum aneurysm diameters than the general population. other animals due to the expense associated with evar stent-graft devices and their specificity to human aortic anatomy, evar is not used in other animals.