Current Status of Endovascular
`Aneurysm Repair: 20 Years of Learning
`Frank R. Arko, III, MD, Erin H. Murphy, MD, Christopher Boyes, MD, Tzvi Nussbaum, MD,
`Stephen G. Lalka, MD, Jeremiah Holleman, MD, and Timothy S. Roush, MD
`
`Parodi first introduced endovascular aneurysm repair (EVAR) in 1991 and since that time it
`has been shown to have a lower 30-day morbididty and mortality compared to open
`surgery. Anatomic constraints governed by the need for adequate access vessels, and
`sufficient proximal and distal landing zones, as well as the need for long-term surveillance,
`have been the main limitations of this technology. Anatomic factors were initially estimated
`to exclude 40% of patients with abdominal aortic aneurysm (AAA). The rapid extension of
`EVAR technology has been complimented by improved access to both high-quality imaging
`modalities and a variety of endografts. These developments have led EVAR to become a
`more practical alternative for patients with ruptured AAA. Early data in this setting is
`encouraging with even more profound reductions in morbidity and mortality than seen in
`the elective repair.
`Semin Vasc Surg 25:131-135 © 2012 Elsevier Inc. All rights reserved.
`
`SINCE ITS INTRODUCTION in 1991, endovascular an-
`
`eurysm repair (EVAR) has been associated with con-
`firmed reductions in 30-day morbidity and mortality com-
`pared to open repair and has evolved into an acceptable and
`often preferable alternative for high-risk patients. The devel-
`opment of percutaneous techniques allows EVAR to be per-
`formed under regional anesthesia, resulting in even faster
`recovery times than initially reported. Anatomic constraints
`governed by the need for adequate access vessels and suffi-
`cient proximal and distal landing zones have been the main
`limitations to extension of this technology. These factors
`were initially estimated to exclude 40% of patients with ab-
`dominal aortic aneurysm.1-3
`Recent advancements in technology have led to the suc-
`cessful manipulation of many of the initial anatomic barriers
`and broadened the breadth of patients now considered for
`EVAR. Unfavorable neck anatomy (ie, angle ⬎60 degrees,
`length ⬍10 mm, severe calcification, or aortic neck throm-
`bus) has been a difficult challenge. Nonetheless, more flexi-
`ble endografts as well as suprarenal fixation have been de-
`signed to accommodate acute angles to improve proximal
`seal and to stabilize endografts in short angled necks, with the
`
`Division of Vascular and Endovascular Surgery, Sanger Heart and Vascular
`Institute, Carolinas Medical Center, Charlotte, NC.
`Address reprint requests to Frank R. Arko, III, Division of Vascular and
`Endovascular Surgery, Sanger Heart and Vascular Institute, Carolinas
`Medical Center, 1001 Blythe Avenue, Suite 300, Charlotte, NC 28203.
`E-mail: farkomd@gmail.com
`
`0895-7967/$-see front matter © 2012 Elsevier Inc. All rights reserved.
`http://dx.doi.org/10.1053/j.semvascsurg.2012.08.002
`
`most recently approved endograft in the United States allow-
`ing for treatment of a 10-mm neck length with up to 60
`degrees of angulation in either a 18Fr (ⱕ28-mm device) or a
`20Fr (up to 36-mm device) delivery system. Furthermore,
`fenestrated or chimney endograft technology has been used
`to extend the proximal landing zone. High spatial and tem-
`poral resolution images and three-dimensional reconstruc-
`tions obtainable with helical computed tomography angiog-
`raphy (CTA) allow precise preoperative planning required
`particularly for these newest technologies. Distal landing
`zones are more easily navigated. Small vessels can be dilated
`or intentionally ruptured, while iliac aneurysms can be
`treated with bell-bottom endograft extensions. Small calci-
`fied access vessels can be dilated or bypassed all together with
`the use of iliac conduits.
`The rapid extension of EVAR technology has been comple-
`mented by improved access to both high-quality imaging
`modalities and a variety of endografts. These developments
`have led to EVAR becoming a more practical alternative for
`patients with ruptured abdominal aortic aneurysm. Early
`data in this setting are encouraging, with even more pro-
`found reductions in morbidity and mortality than seen in the
`elective repair.
`Concerns about the long-term durability of EVAR remain.
`Subsequent lifelong imaging surveillance is currently re-
`quired to monitor for late complications, including endoleak,
`migration, and rupture. The radiation exposure and cost of
`yearly CTA is daunting; however, plain films and duplex
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`132
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`F.R. Arko et al
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`ultrasonography can identify patients at risk for rupture, al-
`lowing more limited use of CTA in patients without evidence
`of sac expansion. Certainly, there remains a higher reinter-
`vention rate after EVAR compared with open repair. In the
`near future, we can even expect the rate of secondary inter-
`ventions to increase, as patients with less favorable anatomy
`are being offered endovascular intervention, and more com-
`plicated repairs involving fenestrated and branched en-
`dografts are being introduced. Most reinterventions can be
`performed endovascularly under regional anesthesia with
`low additional morbidity. Eventually, the rate of secondary
`interventions can be expected to decrease as we gain better
`understanding of these complications, and technology and
`techniques are modified accordingly.
`EVAR will undoubtedly remain a prevalent component in
`the management of abdominal aortic aneurysm. As our tools
`and experience progress, we can expect increased procedural
`durability, fewer secondary interventions, and a decreased
`need for surveillance.
`
`Randomized Trials and EVAR
`There have been four randomized trials comparing endovas-
`cular to open surgery, including the DREAM (Dutch Ran-
`domized Endovascular Aneurysm Repair) trial, the EVAR
`(United Kingdom Endovascular Aneurysm Repair) 1 and 2
`trials, and the OVER (Open versus Endovascular Repair)
`trial. The DREAM trial randomized 351 patients with aneu-
`rysms ⬎5 cm. The cumulative rates of aneurysm-related
`death rates were 5.7% and 2.1% for open and endovascular
`repair, respectively. However, the survival advantage was not
`sustained after the first postoperative year.4-7
`The EVAR 1 trial assessed 543 patients undergoing EVAR
`to 539 patients undergoing open repair. There was a signifi-
`cant improvement in 30-day mortality for EVAR (1.7% com-
`pared with 4.7%). However, there was a significant increase
`in the number of secondary procedures for those undergoing
`EVAR (9.8%) compared with 5.8%. After 1 year, there was a
`similar health-related quality of life among the two groups.
`After 4 years of follow-up, there was a similar 28% mortality
`for both groups, but a lower aneurysm-related mortality for
`the EVAR group. At 8 years, the aneurysm-related survival
`was 93% in both groups, but graft-related complications and
`reinterventions were higher in the endovascular group.5
`The OVER trial performed in the United States randomized
`444 patients to EVAR and 437 patients to open. The 30-day
`mortality was markedly improved with EVAR (0.5% vs 3.0%)
`compared to open repair. At 2 years, mortality was not signifi-
`cantly different for EVAR (7%) compared to open repair (9.8%).
`There were no differences in major morbidity, secondary ther-
`apeutic procedures, or health-related quality of life scores.6
`The EVAR 2 trial evaluated whether EVAR improved survival
`in patients not fit for open surgical repair. A total of 166 patients
`were treated with EVAR, while 172 underwent no intervention.
`Unfortunately, ⬎25% of patients assigned to the no-interven-
`tion group underwent EVAR, and nearly one third of those were
`because of patient preference. As a result, death from rupture at
`30 days in the no-intervention group was 9%, and was similar to
`
`30-day mortality in the EVAR group. These crossovers did not
`alter the main conclusion of the trial, that EVAR had a consid-
`erable 30-day operative mortality in patients already unfit for
`open repair, did not improve survival, and was associated with
`continued surveillance.7
`
`Endograft Devices Currently
`Available in the United States
`The first devices in the United States included the Ancure and
`the AneuRx stent graft systems in 1999 and these were fol-
`lowed by the Gore excluder and the Cook Zenith endograft.
`Both the AneuRx and Ancure had rather nice outcomes in
`clinical trials and resulted in rather good outcomes after ap-
`proval. In the Ancure Phase II trial, there were three periop-
`erative deaths in the open group compared with two in the
`EVAR group. In the AneuRx phase I and II trial, there was a
`2% mortality rate for EVAR. The Gore excluder had a 1% risk
`of mortality in its Phase II clinical trial. The Ancure device
`was a large cumbersome delivery system that is no longer for
`sale. The AneuRx device was a smaller and simpler delivery
`system, but was associated with late-term migration in pa-
`tients with short necks, and this device has been replaced
`with improved technologies and a third-generation device.
`Other devices to have undergone Phase II clinical trials in the
`United States include the Zenith device with an all-cause
`30-day mortality advantage over open controls of (0.5% to
`2.5%), and the enhanced Talent LPS with a 1.3% mortality
`rate.8 Other endografts to have undergone pivotal trials in the
`United States include the Powerlink by Endologix and the
`Endurant endograft by Medtronic. Currently in the United
`States, the most commonly used endografts are the Endurant,
`Excluder, Powerlink, and Zenith. Interestingly, at this point,
`based on available phase II data, a mortality advantage in the
`EVAR trials has not been demonstrated.
`The AneuRx stent graft is a modular bifurcated endograft with
`a self-expanding external nitinol skeleton with a multifilament
`woven polyester graft. The exoskeleton consists of a diamond-
`shaped structure with high radial force. This device allowed for
`treatment of up to a 26-mm infrarenal neck diameter with
`10-mm neck length. The main body was available in 20 to
`28-mm sizes with iliac limbs of 12 to 24 limbs. The stent graft is
`delivered through a 22Fr hydrophilic delivery sheath.
`The Excluder is a modular bifurcated endograft composed of
`a self-expanding nitinol helical configuration that supports an
`expanded polytetraflouroethylene graft. There are anchors
`proximally and an expanded polytetraflouroethylene sealing
`cuff. The main body of the stent graft is typically delivered
`through an 18Fr sheath with the main body of the graft
`measuring between 23 and 31 mm with iliac limbs of 10 to
`20 mm (Fig 1).
`The Zenith is a modular bifurcated stent graft constructed
`with a self-expanding stainless-steel Z-stents that consist of
`an endoskeleton and an exoskeleton. The endoskeleton of
`the graft is in the sealing portion of the first ring and the distal
`seal of the iliac limbs. The rest of the endograft is an exoskel-
`eton. It has a suprarenal bare stent containing barbs. It is
`
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`Current status of endovascular aneurysm repair
`
`133
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`Figure 1 The Excluder is a expanded polytetraflouroethylene graft on the C3 delivery system and is an infrarenal
`device.
`
`indicated for up to a 32-mm infrarenal neck with a 10-mm
`neck length. It comes in sizes of 22 to 36 mm with iliac limbs
`of 8 to 24 mm in diameter. It is delivered through a 22Fr
`hydrophilic sheath.
`The Powerlink is a unibody stent graft created with self-
`expanding cobalt-chromium stents that form an endoskele-
`ton that supports an expanded polytetraflouroethylene graft.
`The first device is deployed on the aortic bifurcation and a
`second piece is placed in a modular fashion just below the
`renal arteries. The second piece can either be a suprarenal or
`infrarenal component. The main body of the device is either
`
`25 or 28 mm and the second piece for seal will go up to 34
`mm in diameter, which can treat up to a 32-mm aortic neck
`diameter that is 15 mm in length. The iliac limbs are 16 mm
`in diameter with extension limbs between 16 and 25 mm. It
`is delivered through a 17Fr hydrophilic sheath (Fig 2).
`The Talent stent graft is a modular bifurcated endograft
`consisting of an endo- and exoskeleton. It is composed of
`nitinol springs sewn to a monofilament polyester fabric ma-
`terial. The proximal end of the stent graft has a five-peak bare
`spring for suprarenal fixation. There is a 10-mm mini-sup-
`port ring at the proximal end of the stent graft for improved
`sealing. The stent graft has sizes of 22 to 36 mm in diameter
`to treat up to a 32-mm neck in diameter with a 10-mm neck
`length. The iliac limbs come in sizes of 8 to 24 mm.
`The most recently approved stent graft is the Endurant
`stent graft. It is a modular stent graft with m-shaped nitinol
`stents attached to a multifilament polyester graft. It possess
`suprarenal fixation with anchoring pins. The main body of
`
`Figure 2 The AFX graft is also expanded polytetraflouroethylene
`with an endoskeleton. It sits on the aortic bifurcation and has both
`infra- and suprarenal proximal extensions.
`
`Figure 3 The Endurant endograft allows for suprarenal stent place-
`ment across the renal arteries.
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`134
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`F.R. Arko et al
`
`nection, and type IV are periprocedural and related to graft
`porosity.10 There is little controversy to management of type
`I and type III endoleaks and that these should be repaired.
`Treatment modalities for these would include extension
`pieces if possible and or conversion of bifurcated devices into
`aorto-uni-iliac devices and a femoral⫺femoral bypass. This is
`typically required when there has been migration of the graft.
`Furthermore, placement of balloon-expandable stents at the
`proximal seal zone can be used to treat a type I endoleak in
`which the stent graft is in good position. If there has been
`late-term dilatation of the proximal aortic neck, the use of
`either fenestrated endografts or chimney grafts has been suc-
`cessful in prevention of surgical conversion (Fig 5). Cer-
`tainly, open surgical conversion can be performed, but has
`been shown to have a significant increase in mortality. In
`selected patients, coil embolization and use of glues have
`been used to treat selective type I endoleaks.11
`Type II endoleaks remain somewhat controversial as to
`what the most appropriate treatment should be. Most would
`agree that persistent endoleaks with sac growth of ⬎5 mm
`should be treated. Treatment can be performed using either
`transarterial coil embolization or translumbar coil emboliza-
`tion. There have been a few reports of laparoscopic repair of
`type II endoleaks. The results of most studies suggest that
`patients typically require multiple reinterventions to treat
`type II endoleaks, this is especially true when lumbar arteries
`are the source of the endoleak, where the initial success rate
`was found to be only 17%.12 However, others have shown
`
`Figure 5 Chimney stents with a Talent converter used to treat a
`migrated endograft with a type I endoleak.
`
`Figure 4 Aptus endostaples in conjunction with a Zenith endograft.
`The staples allow for transmural fixation.
`
`the graft is available in 23 to 36 mm in diameter with iliac
`limbs of 10 to 28 mm. It is indicated to treat up to a 32-mm
`infrarenal aortic neck diameter that is 10 mm in length. It is
`delivered through an 18Fr delivery system for devices up to
`28 mm in diameter. The 32- and 36-mm grafts are delivered
`through a 20Fr delivery system (Fig 3).
`
`Niche Products
`Endostaples have recently been approved for endovascular stent
`graft repair as an adjuvant to improving the proximal neck fix-
`ation (Fig 4). The HeliFx endostaple provides transmural fixa-
`tion that is compatible with the leading aortic stent grafts, in-
`cluding the Zenith, Excluder, AneuRx, Endurant, and Talent.
`Pull force testing in a cadaver study demonstrated that a single
`endostaple provided 9.5 N of migration resistance force. When
`a total of six endostaples were applied, the force the amount of
`force to dislocate the endograft was 79.77 N.9
`
`Complications and
`Reinterventions after EVAR
`Secondary interventions after EVAR continue to persist and
`result in the need for continued surveillance. Although some
`of the complications seen with open repair have been shared
`with EVAR, including graft infection, aortoenteric fistula,
`graft occlusion, and buttock claudication, there are number
`of new complications specific to EVAR alone.
`
`Endoleaks
`Endoleaks are categorized into five main types. Type I en-
`doleaks are associated with endoleaks at attachment sites,
`while type II are retrograde filling of the aneurysm sac from
`collateral vessels, type III are graft fatigue or modular discon-
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`Current status of endovascular aneurysm repair
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`135
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`that use of Onyx glue embolization was associated with a
`greater success rate compared to coil embolization alone.13
`
`Stent Graft Migration
`Migration or movement of the device that can be related to
`endoleaks, aortic remodeling, material fatigue, and progres-
`sion of the aneurysmal disease in the neck, which can lead to
`late type I endoleaks, aneurysm sac revascularization, and
`aneurysm enlargement with the potential for aneurysm rup-
`ture. In a report by the Cleveland Clinic using five different
`devices, overall rate of migration was 3.6% at 1 year. This
`study was based on early-generation devices and with intro-
`duction of new stent grafts this will hopefully decrease.8
`
`Surveillance
`CT scans are routinely used for graft surveillance after endo-
`vascular aneurysm repair. This mode of surveillance was
`used during the clinical trials for follow-up of the endografts,
`sac characteristics, and assessment of endoleaks. Other im-
`aging modalities that can be used include plain abdominal
`films and duplex ultrasonography, or a combination of all
`them. In a recent study, it was shown that patients undergo-
`ing routine CT scans for postoperative surveillance after
`EVAR are at risk for acquiring new solid organ malignancy
`due to radiation exposure. The risk was higher in young
`patients, women, and those exposed to multiple contrast-
`enhanced CT scans. It questioned the need for CT scans after
`EVAR in the absence of endoleaks or a change in aneurysm
`morphology, based on the increased risk of malignancy.14
`
`Conclusions
`Since Parodi’s first report of endovascular aneurysm repair,
`there have a number of different manufactured stent grafts.
`Several that were approved are no longer available for a vari-
`ety of reasons. The current generation of devices approved
`are smaller, track better, and treat morphological challenges
`easier. However, the indications for almost all devices remain
`similar to when EVAR was introduced. This would include a
`15-mm neck length for most devices (10 mm for the Endu-
`rant), ⬍60 degrees of angulation, and a neck diameter of up
`to 32 mm in size. With the smaller hydrophilic delivery sys-
`tems of 18FR to 20Fr, access issues are limited and the need
`for iliac conduits is reduced. EVAR has become the preferred
`treatment for those aneurysms that are suitable candidates for
`repair. There is a clear early mortality benefit for EVAR as
`compared to open surgical repair and, along with its less
`
`invasive nature, patients tend to prefer this procedure. The
`need for continued surveillance has probably become the
`greatest challenge facing EVAR.
`
`References
`1. Parodi JC, Palmaz JC, Barone HD: Transfemoral intraluminal graft im-
`plantation for abdominal aortic aneurysms. Ann Vasc Surg 5:491-499,
`1991
`2. Zarins CK, White RA, Schwarten D, et al for the Investigators of the
`AneuRx trial: Aneurysm stent graft versus open surgical repair of ab-
`dominal aortic aneurysms: multicenter prospective clinical trial. J Vasc
`Surg 29:2920308, 1999
`3. Harris PL, Vallabhaneni SR, Desgranges P, et al: Incidence and risk
`factors of late rupture, conversion, and death after endovascular repair
`of infrarenal aortic aneurysms: the EUROSTAR experience. European
`Collaborators on Stent/Graft Techniques for Aortic Aneurysm Repair. J
`Vasc Surg 32:739-749, 2000
`4. Blankensteijn JD, de Jong SE, Prinssen M, et al: Dutch Randomized
`Endovascular Aneurysm Management Trial Group. Two-year out-
`comes after conventional or endovascular repair of abdominal aortic
`aneurysms. N Engl J Med 352:2398-405, 2005
`5. Greenhalgh RM, Brown LC, Kwong GP, et al: Comparison of endovas-
`cular aneurysm repair with open repair in patients with abdominal
`aortic aneurysm (EVAR trial 1), 30-day operative mortality results:
`randomized controlled trial. Lancet 364(9437):843-848, 2004
`6. Lederle FA, Freischlag JA, Kyriakides TC, et al: Open Versus Endovas-
`cular Repair (OVER) Veterans Affairs Cooperative Study Group. Out-
`comes following endovascular vs open repair of abdominal aortic an-
`eurysm: a randomized trial. JAMA 302:1535-1542, 2009
`7. EVAR Trial Participants: Endovascular aneurysm repair and outcome in
`patients unfit for open repair of abdominal aortic aneurysm in patients
`physically ineligible for open repair. N Engl J Med 362:1872-1880,
`2010
`8. Rutherford RB: Open versus endovascular stent graft repair for abdom-
`inal aortic aneurysms: an historical view. Semin Vasc Surg 25:39-48,
`2012
`9. Melas N, Perdikides T, Saratzis A, et al: Helical Endostaples enhance
`endograft fixation in an experimental model using human cadaveric
`aortas. J Vasc Surg 55:1726-1733, 2012
`10. White GH, Yu W, May J, et al: Endoleak as a complication of endolu-
`minal grafting of abdominal aortic aneurysms: classification, incidence,
`diagnosis, and management. J Endovasc Surg 4:152-168, 1997
`11. Henrikson O, Roos H, Falkenberg M: Ethylene vinyl alcohol copolymer
`(Onyx) to seal type I endoleak. A new technique. Vascular 19:77-81,
`2011
`12. Gallagher KA, Ravin RA, Meltzer AJ, et al: Midterm outcomes after
`treatment of type II endoleaks associated with aneurysm sac expansion.
`J Endovasc Ther 19:182-192, 2012
`13. Abularrage CJ, Patel VI, Conrad MF, et al: Improved long-term results
`using Onyx glue for the treatment of persistent type 2 endoleak after
`endovascular aneurysm repair. J Vasc Surg 2012 May7. Epub ahead of
`print
`14. Motaganahalli R, Martin A, Feliciano B, et al: Estimating the risk of solid
`organ malignancy in patients undergoing routine computed tomogra-
`phy scans after endovascular aneurysm repair. J Vasc Surg 2012 July 9.
`Epub ahead of print.
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