The early 1990s ushered in the era

Transcription

1 CLINICIAN UPDATE CLINICIAN UPDATE Endovascular Abdominal Aortic Aneurysm Repair Jonathan L. Eliason, MD; Gilbert R. Upchurch, Jr, MD The early 1990s ushered in the era of endovascular aneurysm repair (EVAR). Diffusion of this technology, although widespread, has been met with enthusiasm by some and caution by others. Advocates of traditional open surgical techniques maintain that EVAR is costly and that long-term outcomes for patients are inferior. The objectives of the present review are to use a case scenario to highlight the clinical problem, examine current data on the use of EVAR, and to describe the principles behind the safe application of this therapy to patients. Case Scenario A 78-year old white man involved in a motor vehicle crash is evaluated in the emergency department and is found to be without serious injury. Computerized tomography (CT) reveals the incidental finding of a 4.8-cm infrarenal abdominal aortic aneurysm. He has been unaware of the aneurysm but recalls an older brother who had undergone repair of an aneurysm previously. He smokes 2 packs of cigarettes daily, has moderate chronic obstructive pulmonary disease, and has hypertension that is well controlled on a -Blocker. He is referred to a vascular surgeon, who recommends ultrasound surveillance with a 6-month follow-up visit. The subsequent visit reveals aneurysm growth to 5.6 cm, which is confirmed by repeat CT. The patient remains asymptomatic and endovascular aneurysm repair is offered. Clinical Impact of Abdominal Aortic Aneurysm Abdominal aortic aneurysm (AAA) is a significant health risk in older populations, representing the 14th-leading cause of death for the 60- to 85-year old age group in the United States. 1 Necropsy studies from Europe and the United States suggest an overall prevalence of the condition of 2% to 4% for men and 1% to 2% for women. 2,3 The prevalence is greatly affected by case definition, however, with less stringent definitions of AAA in population-based screening studies demonstrating a prevalence of nearly 9% in men and 2% in women. 4 Universally noted are the graded increase in prevalence with advancing age and the increased prevalence with male gender. 2 5 Noninvasive screening programs and a dramatic rise in the elderly population have led to an overall increased incidence of asymptomatic AAA. Despite an aggressive surgical posture toward elective repair before rupture, the incidence of ruptured AAA has also continued to increase. 6,7 Annually to aneurysms are repaired surgically in the United States. 8,9 A steady upward trend in stent graft use reflected in administrative databases implies that EVAR now represents the majority of cases. 10,11 With Markov modeling of hospital costs ranging from $ to for open repair and $ to for EVAR, AAA represents a considerable economic burden. 12,13 Pathophysiology and Current Therapies AAAs are conventionally defined as a 50% increase in aortic diameter compared with the normal proximal aorta. 14 The inciting events leading to AAA formation are not well understood. Some common themes of maturing aneurysms include 1) proteolytic degradation of aortic wall connective tissue, 2) transmural inflammation, 3) immune responses, and 4) increased biomechanical wall stresses. 15 Once AAA formation is initiated, a slow steady growth of the aneurysm until rupture is typical, although on an individual basis this growth rate may be quite variable. Larger-diameter aneurysms in particular, along with female gender, advanced age, smoking, and hypertension have been associated with rapid growth Rapid growth has consequently been associated with increased risk of rupture, 19,20 although initial aneurysm size at diagnosis has the strongest association with rupture. 21 Open From the Cardiovascular Center, University of Michigan, Ann Arbor. Correspondence to Gilbert R. Upchurch, Jr, MD, 1500 E Medical Center Dr, Cardiovascular Center 5372, Ann Arbor, MI. riversu@umich.edu (Circulation. 2008;117: ) 2008 American Heart Association, Inc. Circulation is available at DOI: /CIRCULATIONAHA

2 Eliason and Upchurch Endovascular Abdominal Aortic Aneurysm Repair 1739 aneurysm repair, initially using homografts, has successfully been employed to prevent rupture since the 1950s. 22 The traditional open surgical approach in the modern era is performed either via a retroperitoneal or transperitoneal exposure to obtain proximal and distal aortic control. The aneurysm is then opened, backbleeding branch arteries are ligated, and a prosthetic graft is sutured from the normal proximal aorta to the normal distal aorta or iliac segments. Flow is then restored to the lower extremities and the aneurysm sac is closed over the newly placed synthetic graft. Although effective and durable in treating aneurysms and preventing rupture, this operation has been associated with national mean mortality rates 4% since the 1980s. 23 The excessive mortality associated with open aneurysm repair and a strong trend in surgery toward minimally invasive techniques led to the concept that a covered stent graft might be delivered endoluminally, effectively sealing off the aneurysm wall from systemic pressures, preventing aneurysm rupture, and decreasing associated mortality. In 1991, the first published report of stent graft implantation for AAA in humans suggested that this approach was feasible. 24 Subsequent years have seen a tremendous surge in both the number of endovascular aneurysm repairs performed and technological improvements in stent graft design. Four Food and Drug Administration (FDA) approved devices, each with a slightly different design, are currently being marketed (Figure 1). Rather than relying on sutures to provide fixation, as in open repair, endovascular stent grafts rely on radial forces of self-expanding stents for fixation or self expand in concert with active fixation using hooks or barbs at the proximal aorta fixation site. One FDA-approved device uses bare-wire suprarenal support, as well. With appropriate positioning and adequate fixation, each of these devices redirects the transmission of aortic pulsatile flow and shear forces from the wall of Figure 1. FDA-approved and currently marketed stent graft devices including (A) Medtronic, (B) Gore, (C) Cook, and (D) Endologix. the aneurysm sac to the graft itself. The responses of aneurysm sacs to these changes are variable. 25 The great majority will cease growth or shrink over time. With longer follow-up now being achieved after EVAR, 97% 5-year and 94% 9-year rupture-free survival has been observed. 26 Evidence for Endovascular Repair Two randomized European trials comparing EVAR to open surgery (OS) and 1 randomized trial comparing EVAR to no intervention were published in The first was the Dutch Randomized Endovascular Aneurysm Management (DREAM) trial, randomizing 351 patients with asymptomatic AAAs 5 cm in diameter with suitable stent graft anatomy to OS or EVAR. This study suggested a 30-day benefit in mortality favoring EVAR (1.2% EVAR versus 4.6% OS; P 0.10). 30 The trend toward an early mortality advantage was lost, however, 12 months into the 2-year study follow-up. 27 The second trial, from the United Kingdom, labeled EVAR trial 1 (EVAR 1) was similar to DREAM in comparing EVAR to OS in patients with suitable stent graft anatomy and aneurysm size 5.5 cm. 28 This study randomized a large group of patients (1082), with 94% receiving their allocated treatment. EVAR 1 more clearly demonstrated an early perioperative mortality benefit for EVAR (1.7% EVAR versus 4.7% OS; P 0.009). 31 Blood product use and length of hospital stay also favored EVAR. In contrast, the primary end point of all-cause mortality did not show a lasting benefit for EVAR at the 4-year study conclusion, although aneurysm-related death was decreased (3.5% EVAR versus 6.3% OS; P 0.02). 28 Complication rates (17.6 per 100 person-years EVAR versus 3.3 per 100 person-years OS; P ) and reintervention rates (6.9 per 100 person-years EVAR versus 2.4 per 100 person-years OS; P ) were much higher for stent graft repair than for open repair. EVAR trial 2 (EVAR 2) randomized 338 patients 60 years of age with aneurysms 5.5 cm who were deemed unfit for open surgical repair to EVAR or no intervention. 29 Between the 2 arms of the study, 142 patients died during follow-up, which correlated to a 64% overall mortality by Kaplan Meier estimates at 4 years. This study was complicated by long delays in EVAR after randomization and a 27% patient crossover rate from the no intervention group. In the final analysis, no benefit to EVAR over medical management was detected in either overall mortality or aneurysm-related mortality for patients unfit for open surgery. Ongoing in the United States is the Open Versus Endovascular Repair (OVER) trial, a 9-year study that be-

3 1740 Circulation April 1, 2008 Figure 2. Endograft Implantation with (A) abdominal aortogram to mark the renal arteries, (B) angiogram demonstrating proximal graft deployment in the aortic neck with suprarenal fixation, and (C) completion aortogram after endograft deployment. gan in 2002 comparing endovascular aneurysm repair with standard open surgery using a multicenter randomized trial through the Department of Veteran Affairs (VA) Cooperative Study Group. 32 Clinical Use The FDA approved the transluminal stent graft treatment of abdominal aortic aneurysms in Whereas 2 devices were initially approved, AneuRx by Medtronic (Minneapolis, Minn) and Ancure by Endovascular Technologies Inc (EVT; Menlo Park, Calif), the Ancure device was removed from the market in 2001 after the company failed to submit 2500 medical device reports to the FDA. 34 Three additional devices now also hold FDA approval, including the Zenith (Cook Inc, Bloomington, Ind), Excluder (W.L. Gore and Associates, Flagstaff, Ariz ), and Powerlink (Endologix Inc, Irvine, Calif) systems. Multiple other stent grafts bearing the CE (Conformité Européenne) mark are employed in Europe after demonstrating safety for their intended use. Many stent grafts have undergone modification, with resulting technologies in the third generation and beyond. Despite the diversity among the devices, a generalized discussion of device implantation is indicated. Preprocedural planning is the most critical component of a technically successful endovascular abdominal aortic aneurysm repair. CT provides the backbone for evaluating patient candidacy. In addition to the indications of either an asymptomatic aneurysm of appropriate maximal diameter, or a small aneurysm with features putting it at increased risk of rupture, patients being considered for EVAR must fulfill several anatomic criteria. These include 1) iliofemoral access vessels that will allow safe insertion and deployment of the device, adequate seal, and sufficient length to provide axial support for the graft and 2) an infrarenal aortic neck of adequate length, limited angulation, and appropriate diameter. These anatomic features, as well as the presence or absence of thrombus and calcium at each level, can be evaluated using CT. Cardiac complications are the most common serious perioperative complication of EVAR 30 and the most common cause of late death. 28 Patient selection must therefore also include careful risk stratification of patient comorbidities. The Society for Vascular Surgery has recommended a medical comorbidity grading system for EVAR that emphasizes cardiac, pulmonary, and renal status but also includes hypertension and patient age as relevant factors. 35 This scoring system aids in patient selection and provides a framework for uniform data collection patterns intended to facilitate analysis of outcomes for EVAR. When a decision is made to proceed with EVAR, it can be performed under general anesthesia, local anesthetic with conscious sedation, epidural, or spinal block. The patient is prepped from nipples to knees for the very small but present risk of needing immediate conversion to open surgery. Control of both femoral arteries is typically obtained through small groin incisions, although a totally percutaneous approach has been reported with low complication rates and high incidence of technical success. 36 After bilateral access is obtained, a marking angiogram is typical to confirm preoperative CT measurements and identify the exact location of the lowest renal artery. Most devices follow with ipsilateral main body insertion and deployment at the infrarenal neck, wire cannulation of the contralateral gate, contralateral limb deployment, balloon angioplasty to fully expand the device, and completion angiography (Figure 2). Technical success is achieved when there has been successful access to the arterial system using a remote site, successful deployment of the stent graft with secure proximal and distal fixation, absence of either a type I or type III endoleak (see adverse effects), and a patent stent graft without significant twist, kinks, or obstruction by intraoperative measurements. 37 Patients who undergo EVAR need regular clinical follow-up with appropriate imaging for the remainder of their lives because of the potential for stent graft migration and other causes

4 Eliason and Upchurch Endovascular Abdominal Aortic Aneurysm Repair 1741 of sac repressurization that put the patient at risk of aneurysm rupture. CT is the gold standard for follow-up imaging. Concerns with this method include the cumulative effects of radiation exposure and the effect of repetitive administration of intravenous contrast on renal function. Magnetic resonance imaging/angiography is an alternative for follow-up of most devices but is costly, time consuming, and not universally available. Duplex ultrasound is another option that bears the limitations of relatively small numbers of accredited vascular ultrasound technicians to perform exams and the risk of interoperator variability. Wireless pressure monitoring of the aneurysm sac using a small sensor implanted at the time of EVAR has been proposed as an alternative to other imaging modalities, but no long-term studies currently demonstrate the efficacy of pressure-sensing devices in preventing AAA rupture after EVAR. 38 Efforts to find the optimal method for minimizing the frequency and inconvenience for the patient of follow-up visits while maximizing freedom from aneurysm-related death are ongoing. Complications of Endovascular Aneurysm Repair The numbers of adverse events possible with EVAR are many, because it is a technically complex procedure typically performed on a high-risk patient population. One of the most common adverse events is the need for a secondary intervention of some type. Data from the EUROpean collaborators on Stent/graft Techniques for aortic Aneurysm Repair (EUROSTAR) registry of 2846 patients treated from December 1999 until December 2004 revealed that EVAR resulted in a cumulative incidence of secondary interventions of 6.0%, 8.7%, 12%, and 14% at 1, 2, 3, and 4 years, respectively. 39 Secondary interventions are typically performed when the aneurysm sac has become repressurized because of incomplete exclusion of blood flow from the sac. The term endoleak was created to describe this complication in 1996, 40 and a classification scheme has been adopted (Figure 3). Type I and type III endoleaks are treated with immediate intervention to halt perigraft flow or flow between modular components. Type II endoleaks are typically managed expectantly with intervention reserved for persistent endoleaks in the presence of aneurysm sac enlargement. The presence of a persistent type II endoleak for 6 months, however, has been associated with aneurysm enlargement, increased rate of secondary interventions, and even aneurysm rupture. 44,45 Type IV endoleaks rarely occur with modern stent graft design, and type V endoleaks (endotension), although still reported, 46 are much less frequent after modification of the Gore Excluder device in 2004 to a low-permeability expanded polytetrafluoroethylene layer. 47,48 Secondary interventions occur in a spectrum ranging from diagnostic angiography to endograft removal with conversion to open repair, although the majority are percutaneous treatment of type II endoleaks with source embolization. A related cause of endoleak and potential complication of EVAR is device failure. The integrity of stent graft materials and maintenance of proper positioning within the aneurysm are critical in preventing pressurization of the aneurysm sac and rupture. Material failure includes fracture of any of the metallic components of the stent graft, including stents, hooks, or barbs, or tears in the fabric component of the stent graft. Loss of proper stent graft position can occur for many reasons. Material failure, inadequate proximal or distal seal zone, aneurysm remodeling after EVAR, or features of the vessel, such as thrombus or calcium, that limit stent purchase, have all been implicated in the migration of stent grafts. Each of these modes of failure needs to be analyzed within the context of their clinical significance. A stent fracture that leaves the graft fabric intact and is not in a critical region for maintaining fixation would likely need only follow-up, whereas modular component separation resulting in a large type III endoleak will require urgent intervention to restore stent graft integrity. Approach to the Small Abdominal Aortic Aneurysm Whereas randomized clinical trials have focused on establishing the proper use of EVAR for larger aneurysms, its application for the treatment of small aneurysms is still an area of controversy. Early open aneurysm repair for aneurysms 5.5 cm in diameter does not confer a long-term survival advantage. 49,50 However, retrospective analysis of the large EUROSTAR database revealed that EVAR for aneurysms with diameters between 4.0 cm and 5.4 cm had lower incidence of type I endoleak and improved cumulative freedom from aneurysm-related death relative to 2 comparison groups with aneurysm diameters of 5.5 to 6.4 cm and 6.5 cm. 51 Level 1 evidence is lacking at this time, but the Positive Impact of EndoVascular Options for Treating Aneurysms EarLy (PIVOTAL) and Comparison of surveillance versus Aortic Endografting for Small Aneurysm Repair (CAESAR) trials were initiated in an attempt to provide such evidence. 52 Both are device specific, randomize patients with smaller aneurysms to EVAR or surveillance, and use an FDA-approved Medtronic device or the Cook Zenith device, respectively. Until the results of these trials are published, the optimal management of small aneurysms remains ambiguous and a patient-specific approach that takes into account aneurysm morphology, biology, and patient comorbidities should be used. Published Clinical Guidelines The 2005 American College of Cardiology/American Heart Association practice guidelines for the management of patients with peripheral arterial disease (lower extremity, renal, mesenteric, and abdominal aortic) states that it is reasonable to offer EVAR of infrarenal aortic and/or com-

5 1742 Circulation April 1, 2008 Figure 3. Schematic demonstrating the different types of endoleak after endovascular aneurysm repair. Type I endoleaks occur because of inadequate graft seal resulting in perigraft flow and include (Ia) perigraft flow occurring proximally, (Ib) perigraft flow occurring distally, and (Ic) perigraft flow around an iliac artery occlusion device. Type II endoleaks occur when branch arteries backbleed because of collateral flow. These endoleaks include (IIa) backbleeding inferior mesenteric artery and (IIb) backbleeding lumbar artery. Type III endoleaks occur when flow persists between the segments of a modular graft and include (IIIa) leaks between iliac limbs or an iliac limb and main body component and (IIIb) leaks between main body components. Type IV endoleaks (IV) occur when flow is present through endograft material (graft porosity). Type V endoleak, or, endotension (V), occurs when persistent or recurrent pressurization of the aortic aneurysm exists in the absence of demonstrable endoleak. Drawings prepared by H. Fischer, MFA. mon iliac aneurysms in patients at high risk of complications from open operations because of cardiopulmonary or other associated diseases and that repair may be considered in patients at low or average surgical risk. 53 Whereas this document proposes a treatment algorithm setting the threshold for surgical repair at 5.5 cm except in cases of rapid expansion, it also states, Ultimately, once an infrarenal aortic aneurysm reaches an appropriate size for graft replacement, a choice must be made between a traditional open operation or endovascular repair. Like all other aspects of aneurysm management, this decision requires a balanced judgment of relative risks. Other features, such as saccular aneurysm morphology, patient gender, heredity, uncontrolled hypertension, and chronic obstructive pulmonary disease may also be important considerations. 54 Conclusions The patient described in the vignette meets all the recommended criteria for aneurysm repair. His age, ethnic background, and heavy smoking history are typical of patients with this disease process. The absolute aneurysm size and history of rapid expansion suggest that repair would offer a mortality benefit. Before offering EVAR, however, anatomic suitability must be confirmed by an experienced clinician using accurate imaging. Once it is established that the patient is an appropriate candidate for endovascular repair, the risks and benefits of both open and endovascular approaches should be discussed. Given the advanced age and pulmonary morbidity

6 Eliason and Upchurch Endovascular Abdominal Aortic Aneurysm Repair 1743 of this patient, endovascular repair would be appropriate therapy. None. Disclosures References 1. National Center for Health Statistics (NHCS), National Vital Statistics System, WISQARS Query: 20 Leading Causes of Death, United States, , All Races, Both Sexes. Available at: cdc.gov/sasweb/ncipc/leadcaus10.html. Accessed July 25, Bengtsson H, Bergqvist D, Sternby NH. Increasing prevalence of abdominal aortic aneurysms: a necropsy study. Eur J Surg. 1992;158: McFarlane MJ. The epidemiologic necropsy for abdominal aortic aneurysm. JAMA. 1991; 265: Singh K, Bonaa KH, Jacobsen BK, Bjork L, Solberg S. Prevalence of and risk factors for abdominal aortic aneurysms in a population-based study: the Tromso Study. Am J Epidemiol. 2001;154: Lilienfeld DE, Gunderson PD, Sprafka JM, Vargas C. Epidemiology of aortic aneurysms: I. Mortality trends in the United States, 1951 to Arteriosclerosis. 1987; 7: Acosta S, Ogren M, Bengtsson H, Bergqvist D, Lindblad B, Zdanowski Z. Increasing incidence of ruptured abdominal aortic aneurysm: a population-based study. J Vasc Surg. 2006;44: Bengtsson H, Bergqvist D. Ruptured abdominal aortic aneurysm: a populationbased study. J Vasc Surg. 1993;18: Gillum RF. Epidemiology of aortic aneurysm in the United States. J Clin Epidemiol. 1995;48: Kozak LJ, DeFrances CJ, Hall MJ. National hospital discharge survey: 2004 annual summary with detailed diagnosis and procedure data. Vital Health Stat : Cowan JA Jr, Dimick JB, Henke PK, Rectenwald J, Stanley JC, Upchurch GR Jr. Epidemiology of aortic aneurysm repair in the United States from 1993 to Ann N Y Acad Sci. 2006;1085: McPhee JT, Hill JS, Eslami MH. The impact of gender on presentation, therapy, and mortality of abdominal aortic aneurysm in the United States, J Vasc Surg. 2007;45: Bosch JL, Lester JS, McMahon PM, Beinfeld MT, Halpern EF, Kaufman JA, Brewster DC, Gazelle GS. Hospital costs for elective endovascular and surgical repairs of infrarenal abdominal aortic aneurysms. Radiology. 2001;220: Patel ST, Haser PB, Bush HL Jr, Kent KC. The cost-effectiveness of endovascular repair versus open surgical repair of abdominal aortic aneurysms: a decision analysis model. J Vasc Surg. 1999;29: Johnston KW, Rutherford RB, Tilson MD, Shah DM, Hollier L, Stanley JC. Suggested standards for reporting on arterial aneurysms. Ad Hoc Committee on Reporting Standards, Society for Vascular Surgery and North American Chapter, International Society for Cardiovascular Surgery. J Vasc Surg. 1991;13: Wassef M, Baxter BT, Chisholm RL, Dalman RL, Fillinger MF, Heinecke J, Humphrey JD, Kuivaniemi H, Parks WC, Pearce WH, Platsoucas CD, Sukhova GK, Thompson RW, Tilson MD, Zarins CK. Pathogenesis of abdominal aortic aneurysms: a multidisciplinary research program supported by the National Heart, Lung, and Blood Institute. J Vasc Surg. 2001;34: Solberg S, Singh K, Wilsgaard T, Jacobsen BK. Increased growth rate of abdominal aortic aneurysms in women: the Tromso tudy. Eur J Vasc Endovasc Surg. 2005;29: Mofidi R, Goldie VJ, Kelman J, Dawson AR, Murie JA, Chalmers RT. Influence of sex on expansion rate of abdominal aortic aneurysms. Br J Surg. 2007;94: Cronenwett JL. Variables that affect the expansion rate and rupture of abdominal aortic aneurysms. Ann N Y Acad Sci. 1996; 800: Limet R, Sakalihassan N, Albert A. Determination of the expansion rate and incidence of rupture of abdominal aortic aneurysms. J Vasc Surg. 1991;14(4): Schewe CK, Schweikart HP, Hammel G, Spengel FA, Zollner N, Zoller WG. Influence of selective management on the prognosis and the risk of rupture of abdominal aortic aneurysms. Clin Investig. 1994;72(8): Lederle FA, Johnson GR, Wilson SE, Ballard DJ, Jordan WD Jr, Blebea J, Littooy FN, Freischlag JA, Bandyk D, Rapp JH, Salam AA, Veterans Affairs Cooperative Study #417 Investigators. Rupture rate of large abdominal aortic aneurysms in patients refusing or unfit for elective repair. JAMA. 2002;287: De Bakey ME, Cooley DA. Treatment of aneurysms of the aorta by resection and restoration of continuity with aortic homograft. Angiology. 1954;5: Eliason JL, Wainess RM, Dimick JB, Cowan JA Jr, Henke PK, Stanley JC, Upchurch GR Jr. The effect of secondary operations on mortality following abdominal aortic aneurysm repair in the United States: Vasc Endovascular Surg. 2005;39: Parodi JC, Palmaz JC, Barone HD. Transfemoral intraluminal graft implantation for abdominal aortic aneurysms. Ann Vasc Surg. 1991;5: Greenberg RK, Deaton D, Sullivan T, Walker E, Lyden SP, Srivastava SD, Ouriel K, Ivanc T, Burton T, Mayo J. Variable sac behavior after endovascular repair of abdominal aortic aneurysm: analysis of core laboratory data. J Vasc Surg. 2004;39: Brewster DC, Jones JE, Chung TK, Lamuraglia GM, Kwolek CJ, Watkins MT, Hodgman TM, Cambria RP. Long-term outcomes after endovascular abdominal aortic aneurysm repair: the first decade. Ann Surg. 2006;244: Blankensteijn JD, de Jong SE, Prinssen M, van der Ham AC, Buth J, van Sterkenburg SM, Verhagen HJ, Buskens E, Grobbee DE, Dutch Randomized Endovascular Aneurysm Management (DREAM) Trial Group. Two-year outcomes after conventional or endovascular repair of abdominal aortic aneurysms. N Engl J Med. 2005;352: EVAR Trial Participants. Endovascular aneurysm repair versus open repair in patients with abdominal aortic aneurysm (EVAR trial 1): randomised controlled trial. Lancet. 2005;365: EVAR Trial Participants. Endovascular aneurysm repair and outcome in patients unfit for open repair of abdominal aortic aneurysm (EVAR trial 2): randomised controlled trial. Lancet. 2005;365: Prinssen M, Verhoeven EL, Buth J, Cuypers PW, van Sambeek MR, Balm R, Buskens E, Grobbee DE, Blankensteijn JD, Dutch Randomized Endovascular Aneurysm Management (DREAM) Trial Group. A randomized trial comparing conventional and endovascular repair of abdominal aortic aneurysms. N Engl J Med. 2004;351: Greenhalgh RM, Brown LC, Kwong GP, Powell JT, Thompson SG, EVAR Trial Participants. Comparison of endovascular aneurysm repair with open repair in patients with abdominal aortic aneurysm (EVAR trial 1), 30-day operative mortality results: randomised controlled trial. Lancet. 2004;364: Lederle FA. A summary of the contributions of the VA cooperative studies on abdominal aortic aneurysms. Ann N Y Acad Sci. 2006; 1085: Premarket approval database: AneurRx Stent Graft System. Washington DC: Food and Drug Administration, Center for Devices and Radiological Health. Available at: cfdocs/cfpma/pma.cfm?id Accessed August 2, Bren L. Investigators Reports: Company Caught in Coverup of Medical Device Malfunctions. Available at: fdac/departs/2003/603_irs.html. Accessed August 2, Chaikof EL, Fillinger MF, Matsumura JS, Rutherford RB, White GH, Blankensteijn JD, Bernhard VM, Harris PL, Kent KC, May J, Veith FJ, Zarins CK. Identifying and grading factors that modify the outcome of endovascular aortic aneurysm repair. J Vasc Surg. 2002;35: Lee WA, Brown MP, Nelson PR, Huber TS. Total percutaneous access for endovascular aortic aneurysm repair ( Preclose technique). J Vasc Surg. 2007;45: Chaikof EL, Blankensteijn JD, Harris PL, White GH, Zarins CK, Bernhard VM, Matsumura JS, May J, Veith FJ, Fillinger MF,

7 1744 Circulation April 1, 2008 Rutherford RB, Kent KC, Ad Hoc Committee for Standardized Reporting Practices in Vascular Surgery of The Society for Vascular Surgery/American Association for Vascular Surgery. Reporting standards for endovascular aortic aneurysm repair. J Vasc Surg. 2002;35: Kurosawa K, Ohta H, Sumi M, Ohki T. Physiologic monitoring data: will it change our follow-up paradigms? Semin Vasc Surg. 2007;20: Hobo R, Buth J. Secondary interventions following endovascular abdominal aortic aneurysm repair using current endografts: a EUROSTAR report. J Vasc Surg. 2006;43: White GH, Yu W, May J. Endoleak a proposed new terminology to describe incomplete aneurysm exclusion by an endoluminal graft. J Endovasc Surg. 1996;3: White GH, Yu W, May J, Chaufour X, Stephen MS. Endoleak as a complication of endoluminal grafting of abdominal aortic aneurysms: classification, incidence, diagnosis, and management. J Endovasc Surg. 1997;4: Gilling-Smith G, Brennan J, Harris P, Bakran A, Gould D, McWilliams R. Endotension after endovascular aneurysm repair: definition, classification, and strategies for surveillance and intervention. J Endovasc Surg. 1999;6: White GH, May J, Petrasek P, Waugh R, Stephen M, Harris J. Endotension: an explanation for continued AAA growth after successful endoluminal repair. J Endovasc Surg. 1999;6: Fairman RM, Nolte L, Snyder SA, Chuter TA, Greenberg RK, Zenith Investigators. Factors predictive of early or late aneurysm sac size change following endovascular repair. J Vasc Surg. 2006;43: Jones JE, Atkins MD, Brewster DC, Chung TK, Kwolek CJ, LaMuraglia GM, Hodgman TM, Cambria RP. Persistent type 2 endoleak after endovascular repair of abdominal aortic aneurysm is associated with adverse late outcomes. J Vasc Surg. 2007;46: Iyer VS, Mackenzie KS, Corriveau MM, Steinmetz OK. Reversible endotension associated with excessive warfarin anticoagulation. J Vasc Surg. 2007;45: Cho JS, Dillavou ED, Rhee RY, Makaroun MS. Late abdominal aortic aneurysm enlargement after endovascular repair with the Excluder device. J Vasc Surg. 2004;39: , 2004; discussion Tanski W III, Fillinger M. Outcomes of original and low-permeability Gore Excluder endoprosthesis for endovascular abdominal aortic aneurysm repair. J Vasc Surg. 2007; 45: Lederle FA, Wilson SE, Johnson GR, Reinke DB, Littooy FN, Acher CW, Ballard DJ, Messina LM, Gordon IL, Chute EP, Krupski WC, Busuttil SJ, Barone GW, Sparks S, Graham LM, Rapp JH, Makaroun MS, Moneta GL, Cambria RA, Makhoul RG, Eton D, Ansel HJ, Freischlag JA, Bandyk D, Aneurysm Detection and Management Veterans Affairs Cooperative Study Group. Immediate repair compared with surveillance of small abdominal aortic aneurysms. N Engl J Med. 2002;346: United Kingdom Small Aneurysm Trial Participants. Long-term outcomes of immediate repair compared with surveillance of small abdominal aortic aneurysms. N Engl J Med. 2002;346: Peppelenbosch N, Buth J, Harris PL, van Marrewijk C, Fransen G, EUROSTAR Collaborators. Diameter of abdominal aortic aneurysm and outcome of endovascular aneurysm repair: does size matter? A report from EUROSTAR. J Vasc Surg. 2004;39: Cao P, CAESAR Trial Collaborators. Comparison of surveillance vs Aortic Endografting for Small Aneurysm Repair (CAESAR) trial: study design and progress. Eur J Vasc Endovasc Surg. 2005;30: Hirsch AT, Haskal ZJ, Hertzer NR, Bakal CW, Creager MA, Halperin JL, Hiratzka LF, Murphy WR, Olin JW, Puschett JB, Rosenfield KA, Sacks D, Stanley JC, Taylor LM Jr, White CJ, White J, White RA, Antman EM, Smith SC Jr, Adams CD, Anderson JL, Faxon DP, Fuster V, Gibbons RJ, Hunt SA, Jacobs AK, Nishimura R, Ornato JP, Page RL, Riegel B. American Association for Vascular Surgery; Society for Vascular Surgery; Society for Cardiovascular Angiography and Interventions; Society for Vascular Medicine and Biology; Society of Interventional Radiology; ACC/AHA Task Force on Practice Guidelines Writing Committee to Develop Guidelines for the Management of Patients With Peripheral Arterial Disease; American Association of Cardiovascular and Pulmonary Rehabilitation; National Heart, Lung, and Blood Institute; Society for Vascular Nursing; TransAtlantic Inter-Society Consensus; Vascular Disease Foundation. ACC/AHA 2005 Practice Guidelines for the management of patients with peripheral arterial disease (lower extremity, renal, mesenteric, and abdominal aortic): a collaborative report from the American Association for Vascular Surgery/Society for Vascular Surgery, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, Society of Interventional Radiology, and the ACC/AHA Task Force on Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Peripheral Arterial Disease): endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation; National Heart, Lung, and Blood Institute; Society for Vascular Nursing; TransAtlantic Inter-Society Consensus; and Vascular Disease Foundation. Circulation. 2006;113: e463 e Brewster DC, Cronenwett JL, Hallett JW Jr, Johnston KW, Krupski WC, Matsumura JS, Joint Council of the American Association for Vascular Surgery and Society for Vascular Surgery. Guidelines for the treatment of abdominal aortic aneurysms: report of a subcommittee of the Joint Council of the American Association for Vascular Surgery and Society for Vascular Surgery. J Vasc Surg. 2003;37: