Endovascular devices for abdominal aortic repair

INTRODUCTION — Endovascular aortic repair requires that specific anatomic criteria are fulfilled, and, for those with appropriate anatomy, this technique has become a preferred approach and allows the treatment of patients who might not otherwise be candidates for surgical aortic repair due to medical comorbidities.

Endovascular repair with abdominal stent-graft devices is primarily used to treat infrarenal abdominal aortic aneurysm with or without associated iliac artery aneurysm. Although not yet approved for clinical use in the United States, branched and fenestrated endovascular aortic devices have been developed to allow perfusion into specific aortic branches depending upon the level of repair (eg, renal artery, internal iliac artery). These advanced devices allow endovascular management of juxtarenal and potentially suprarenal aneurysms, and preservation of hypogastric flow when an adequate landing zone in the common iliac artery is not present.

The placement of aortic endovascular grafts is associated with device-related complications, which can include component separation, stent-graft buckling, and migration over time. Secondary intervention is frequently needed [1-3]. Although the long-term outcomes of the later-generation devices are favorable, lifelong surveillance is required to monitor for delayed graft-related adverse events.

The specific devices available for endovascular repair of the abdominal aorta will be reviewed here. The indications for, placement of, and complications of these devices are discussed elsewhere. (See "Endovascular repair of abdominal aortic aneurysm" and "Complications of endovascular abdominal aortic repair".)

AORTIC ANATOMY — The aorta is the major arterial conduit conveying blood from the heart to the systemic circulation. It originates immediately beyond the aortic valve ascending initially, then curving to form the aortic arch, and finally descending caudally adjacent to the spine. The descending thoracic aorta continues through the hiatus of the diaphragm to become the abdominal aorta, which extends into the retroperitoneum to its bifurcation into the common iliac arteries at the level of the fourth lumbar vertebra. The abdominal aorta lies slightly left of the midline to accommodate the inferior vena cava, which is in close apposition. The branches of the abdominal aorta (superior to inferior) (figure 1) include the left and right inferior phrenic arteries, left and right middle suprarenal arteries, the celiac axis, superior mesenteric artery, left and right renal arteries in addition to occasional accessory renal arteries, left and right gonadal arteries, inferior mesenteric artery, the paired lumbar arteries (L1-L4), and middle sacral artery. The abdominal aorta bifurcates into the left and right common iliac arteries, which most often arise at the level of the fourth lumbar vertebra. The common iliac artery bifurcates into the external iliac and internal iliac arteries at the pelvic inlet. The internal iliac artery has superior and inferior divisions that supply the pelvic viscera and muscles. The external iliac artery passes beneath the inguinal ligament to become the common femoral artery [4].

BASIC PRINCIPLES — Endovascular aneurysm repair refers to the insertion of endovascular graft components (figure 2), usually via a femoral approach. The endovascular graft is constructed by the in vivo delivery and deployment of the device components in an established order determined by the specific anatomy of the patient. Upon deployment, the endograft expands, contacting the aortic wall proximally and the iliac vessels distally, excluding the aneurysmal aortic sac from blood flow and pressure.

Although there are significant variations in endovascular graft design, three types of components are common to all: a delivery system, main body device, and device (limb) extensions.

Delivery system — The various endograft components are typically delivered through the femoral artery, either by direct surgical cut-down or percutaneously. If the femoral artery is too small to accommodate the delivery system, access can be obtained by suturing a synthetic graft of appropriate diameter (often 10 mm) to the common iliac artery to create an iliac conduit through a retroperitoneal incision. The size of the delivery system varies depending upon the device diameter required to provide proper endograft fixation.

Main device — The main body device for the abdominal aorta is usually bifurcated. Endovascular grafts rely primarily upon outward radial force in the proximal graft to maintain the positioning of the graft. Fixation systems may also include barbs or a suprarenal uncovered extension. Bifurcated abdominal aortic grafts require adjunctive placement of iliac artery limbs to complete the graft and seal. The iliac limbs on the main body device vary in length depending upon whether the graft is a two- or three-component graft. Two-component grafts have one short and one long iliac limb. Three-component devices have one short limb and one limb of variable length.

Endovascular grafts for the abdominal aorta are generally bifurcated; however, some situations require the use of a unibody (ie, not bifurcated) graft, also known as an aorta-uni-iliac (AUI) device. These grafts are used in patients with severe unilateral iliac artery stenosis or occlusion. AUI devices can also be used for the treatment of some ruptured aneurysms. A bifurcated-to-unilateral graft conversion kit can be used in the situation when contralateral iliac artery access or contralateral gate cannulation is difficult or impossible. This kit effectively turns a bifurcated main body graft into a unilateral graft by covering or occluding one of the iliac limbs proximally. After deployment of an AUI device, a plug may be inserted into the contralateral iliac artery to prevent retrograde flow of blood into the aneurysm sac, if needed. The contralateral extremity typically requires a femoro-femoral crossover bypass for perfusion. (See "Endovascular repair of abdominal aortic aneurysm", section on 'Choice of graft' and "Endovascular repair of abdominal aortic aneurysm", section on 'Endograft placement'.)

Extensions — One or more extension devices may be needed to provide a complete proximal or distal seal. Following the deployment of the main device and any necessary contralateral limbs or extensions, an aortogram is performed to assure that the endograft has completely excluded the aneurysm from the circulation. The term "endoleak" was coined to describe the persistence of blood flow into the aneurysm. If additional ballooning of the device does not firmly appose the graft to the aortic wall and eliminate a type I endoleak, placement of additional proximal aortic or iliac extensions may be needed.

ABDOMINAL DEVICES — The use of abdominal endovascular devices has become the first-line approach to manage many aortic pathologies. The main indication for these devices in the abdominal aorta is treatment of abdominal aortic aneurysm (AAA). Endovascular repair of the abdominal aorta has also been used to treat isolated infrarenal aortic dissection, traumatic aortic injuries, and aortic atheroembolism [5,6]. Endovascular grafts for the abdominal aorta are generally modular, bifurcated devices; however, an aorta-uni-iliac (AUI) device or bifurcated-to-unilateral graft conversion kit may be needed. (See 'Main device' above.)

Controlled comparisons of abdominal aortic stent-grafts have not been performed. Devices available to treat the abdominal aorta include the AFX2, Alto, Aorfix, Endurant, Excluder, Incraft, Treovance, and Zenith grafts (table 1). Several investigational devices are in early clinical testing phases. The essential features of the grafts approved for use in the United States and clinical data supporting them are discussed below. The features of these grafts are summarized in the table (table 1). (See 'Withdrawn/investigational devices' below.)

AFX2 — The AFX endovascular graft was initially approved by the US Food and Drug Administration (FDA) in 2011, and over time, the manufacturer changed to the device based on the higher incidence of type III endoleak seen with the early versions. The AFX2 next-generation system replaced the original AFX graft in 2016.

The AFX2 system (table 1) is a modular bifurcated graft composed of ePTFE supported by a self-expanding internal cobalt-chromium alloy skeleton. The main body of the endograft has symmetric iliac limbs. The proximal graft has a bare stent for active fixation, and the bifurcation of the graft rests on the aortic bifurcation for anatomic distal fixation.

The main device is available in diameters ranging from 22 to 28 mm in lengths ranging from 6 to 10 cm with limbs measuring 13 or 16 mm in diameter and lengths from 3 to 5.5 cm [7]. The limb extensions range from 16 to 20 mm in diameter in lengths from 5.5 to 8.8 cm. The main device is delivered in a 21-French (7 mm) sheath, and the contralateral limb is delivered through a 17- or 19-French (5.67, 6.33 mm) sheath.

The FDA has evaluated information that suggests a higher-than-expected risk of type III endoleaks occurring with the AFX endovascular grafts with Duraply graft material (ie, AFX with Duraply or AFX2). The FDA recommends that health care providers consider using available alternative treatment options for AAA patients rather than using the AFX2 device [8,9]. In December 2022, the FDA issued an updated safety communication that included information about new labeling and a required postmarket study for the AFX2 Endovascular AAA System to better inform patients and health care providers of the risk of Type III endoleaks [8]. In addition, the FDA emphasized the importance of at least yearly, lifelong follow-up with a health care provider for all patients who had their AAA treated with any AFX endovascular graft to monitor for Type III endoleaks.

Alto — The Alto stent-graft system is based on the Ovation iX graft, which was recalled, as their next-generation polymer-based abdominal stent-graft system. It was approved for use in the United States in March 2020.

The Alto stent-graft system requires an aortic landing zone for the sealing ring 7 mm below the inferior renal artery, and an inner wall diameter of ≥16 mm and ≤30 mm. The required distal iliac landing zone is at least 10 mm in length, with an inner wall diameter of ≥8 mm and ≤25 mm. Some of the primary modifications to the Ovation iX graft include locating the sealing ring 7 mm below the renal arteries, inclusion of webbing between the aortic body legs at the bifurcation, and incorporation of an integrated balloon into the delivery system.

The ELEVATE (Expanding Patient Applicability with Polymer Sealing Ovation Alto Stent Graft) investigational device exemption clinical study completed the enrollment of 75 patients in 2018. On follow-up, 95 percent of patients (58 out of 61) did not have device- or aneurysm-related complication at the one-year follow-up. The trial aimed at evaluating the effectiveness of the Alto graft in patients with AAA at 12 months. A prospective multicenter multinational postapproval study will collect confirmatory safety and effectiveness data with a five-year follow-up.

Aorfix — The Aorfix AAA endograft is a bifurcated woven polyester graft supported by a nitinol skeleton. Active fixation is provided by proximal nitinol hooks. The graft is intended to treat angulated aortic necks for up to 90 degrees and tortuous iliac anatomy. The proximal portion of the main graft body is fish-mouthed (rather than circular) in shape, and when positioned properly, the surface area of the potentially achievable seal-zone is increased in the anterior-to-posterior dimension. Because of this feature, the distance from the superior mesenteric artery to the lowest renal artery needs to be at least 15 mm in length to prevent inadvertent coverage of the superior mesenteric artery orifice during graft deployment. The Aorfix graft was approved for clinical use and available in Europe and later approved for use in the US, supported by data from the PYTHAGORAS trial. Short-term and mid-term data from European trials have confirmed the safety of the device and its suitability for treating hostile aorto-iliac anatomy [10]. The five-year outcomes of the PYTHAGORAS trial reported on 218 patients, 151 of whom were categorized in the highly angulated neck group. There were no reported type I or III endoleak. Freedom from aneurysm-related mortality was 96 percent; freedom of aneurysm-related rupture was 99 percent; and freedom of device-related secondary intervention was 83 percent. The PYTHAGORAS trial of the High Angle Aorfix Bifurcated Stent Graft was completed in July 2020 [11,12].

Endurant — The Endurant endograft (table 1) is a modular, bifurcated device composed of a multifilament polyester fabric with an external self-expanding support structure of M-shaped electro-polished nitinol stents. Proximally, it has a suprarenal nitinol stent with anchoring pins for suprarenal fixation. The graft design is intended to treat aneurysms with more challenging anatomy (eg, neck angulation).

The main device is available in diameters that range from 23 to 36 mm for the main body and 13 to 20 mm for the ipsilateral limb and in lengths of 12.4, 14.5 and 16.6 cm [13]. The contralateral iliac stent component ranges from 10 to 28 mm in diameter with 8.2-, 9.3-, and 12.4-cm lengths. The internal diameter of the delivery sheath for the bifurcated grafts is 18 or 20 French (6.0, 6.67 mm), and the sheaths for other components range from 14 to 16 French (4.67 to 5.33 mm).

A single-arm, multicenter trial evaluating the safety and performance of the Endurant graft was conducted at 26 sites in the United States and enrolled 150 patients between April 2008 and May 2009 [14]. The technical success rate was 99.3 percent. One failure was due to inability to cannulate the contralateral gate, and one patient ruptured during the procedure but was still treated successfully. The perioperative mortality (30-day) rate was zero, and the incidence of major adverse events was 4 percent. At one-year follow-up there were no migrations, ruptures, open conversions, or graft-related endoleaks (type I or III). Ten aneurysm-related reinterventions were performed during the first year of follow-up, mostly for graft limb thrombosis or stenosis (five) or type II endoleak (two). Aneurysm sac diameter decreased >5 mm at one year in 47 percent of patients and remained stable in 53 percent. No instances of sac growth were reported. Late deaths occurred in 4.7 percent of patients but were not related to the aneurysm repair. The ENGAGE registry, which has enrolled 1262 patients from 2009 to 2011 at 39 sites around the world, has reported similar outcomes at 30 days (all patients) and at one year for 500 patients [15].

A European trial enrolled 80 patients between November 2007 and August 2008, 71 of whom had moderate infrarenal aortic neck angulation and 9 with a high degree of angulation (60° to 75°) [16]. The device was successfully delivered and deployed in all cases. At one-year follow-up, all-cause mortality was 5 percent, with potentially one device-related death. Serious adverse events were comparable between the high- and moderate-angulation groups. There were no device migrations, stent fractures, aortic ruptures, or conversions to open repair. Maximal aneurysm diameter decreased >5 mm in 43 percent of cases. Three secondary endovascular procedures were performed for outflow vessel stenosis, graft limb occlusion, and iliac extension, resulting in a secondary patency rate of 100 percent. No re-interventions were required in the high-angulation group.

Five-year outcomes of the Endurant stent-graft regulatory trial in the United States demonstrated that this device appeared to be durable with limited adverse events [17]. Using Kaplan-Meier estimates, freedom from AAA-related mortality was 99.2 percent; all-cause mortality was 18 percent. There were no endograft migrations, fractures, or conversions to open repair. Endoleaks were identified in 7/83 patients (8.4 percent) and included type II endoleaks (6), and one endoleak of indeterminate origin. Maximum AAA diameter increased by 5 mm in 5/83 (6 percent) patients. Eighteen secondary interventions were required in 15 patients (11 percent): 12 for endoleak, 4 for limb occlusion, 1 for stenosis, and 1 for thromboembolism.

The five-year outcomes of the Endurant stent-graft reported from the ENGAGE registry demonstrated the sustained safety, effectiveness, and durability of the device [18]. The ENGAGE registry included a total of 1263 patients with AAA enrolled from 2009 to 2011 at 79 centers across 30 countries. Freedom from aneurysm-related mortality, aneurysm rupture, secondary procedures, and conversion to open repair at five years was 97.8, 98.6, 84.3, and 97.9 percent, respectively. The five-year freedom from type IA endoleaks was 95.2 percent and for type III endoleaks 97.4 percent.

The performance of the Endurant stent-graft in short aortic necks was reported in patients treated with the Endurant graft in conjunction with the Heli-FX EndoAnchor implant [19]. The outcomes at one year in a cohort of 70 patients reported type IA endoleaks in four patients, of which three resolved spontaneously by the 12-month follow-up. There was an additional type IA endoleak through the 12-month follow-up that has not resulted in AAA enlargement nor required a secondary procedure. The Kaplan-Meier estimate for freedom from secondary endovascular procedures and all-cause mortality was 95.4 and 92.7 percent through one year, respectively. This approach may be an option in patients with hostile anatomy and comorbidities precluding other repair options, but longer-term follow-up is required.

Excluder

Standard graft — The Excluder device (table 1) is a self-expanding modular bifurcated two-component graft made of expanded polytetrafluoroethylene (ePTFE) material bonded to a nitinol exoskeleton and covered with a reinforcing sleeve of ePTFE/fluorinated ethylene propylene (FEP) composite film. The proximal graft and ipsilateral limb have scalloped flares lined with graft material. The proximal graft and distal limbs have an ePTFE sealing cuff to improve apposition to the arterial wall.

The main body graft is available in diameters ranging from 23 to 35 mm with an ipsilateral limb measuring 12 or 14.5 mm [20]. The length of the body of the graft ranges from 12 to 18 cm. The contralateral limb is available in diameters ranging from 12 to 20 mm and lengths from 9.5 to 13.5 cm. The main device is delivered in an 18- or 20-French (6- to 6.67-mm) sheath. The device employs a unique delivery system that relies upon a pull-cord similar to a dog food bag. Once the device is positioned, the deployment line unlaces from the middle of the device toward both ends.

The safety and efficacy of the Excluder graft was evaluated in a prospective nonrandomized trial that enrolled 334 patients (235 endovascular and 99 open surgical control patients) in 19 different centers [21]. Compared with the control group, the Excluder group had less blood loss, shorter length of hospital stay, and decreased length of recovery. At one-year and two-year follow-up, the Excluder group had a significantly lower incidence of major complications (33 versus 67 percent). There were no significant differences between the groups in survival rate at two-year follow-up. In the Excluder group, the incidence of aneurysm-related death was 2.6 percent, but there were no late aneurysm ruptures at four-year follow-up [22].

Aneurysm sac enlargement, defined as ≥5 mm change from baseline size, occurred in 3 and 36 percent of patients at one and five years, respectively, after graft placement in the Excluder 98-03 Pivotal Trial, the majority occurring without any apparent endoleaks [23]. This phenomenon led the company to release an updated version of the Excluder device in July 2004. The new device incorporated the additional low-permeability layer (FEP) to reduce exudation of fluid flow across the graft material. Following these improvements, minimal aneurysm sac expansion and significant aneurysm sac regression have been found after endovascular repair of abdominal aortic aneurysms using the new Excluder device at one year [24] and with longer follow-up at 5 and 10 years [25,26]. In one study of 179 patients, the estimated 10-year rate of aneurysm-related death or rupture was 2.1 percent (old and new designs included).

In a retrospective review of 461 patients from the Italian Excluder registry, long-term outcomes were evaluated using life-table analysis [27]. The 10-year cumulative survival was 62.5 percent (95% CI 55.5 to 69.1 percent). Estimated freedom graft related complications were 90.5 percent at 5 years, 89.2 percent at 7 years, and 88.4 percent at 10 years. Freedom from reintervention at 5, 7, and 10 years was 87.7, 82.4, and 80.6 percent, respectively. Estimated freedom from aorta-related mortality was 97.2 percent at 10 years. As documented by other long-term studies and with other endografts, observed late adverse events and new-onset endoleaks emphasize the need for long-term surveillance [28].

The Excluder proximal deployment system was redesigned to allow for repositioning prior to final deployment, with the aim of improving the proximal deployment accuracy and to aid in cannulating the contralateral gate. To track the real-world performance of the new C3 Excluder stent-graft, the Global Registry for Endovascular Aortic Treatment (GREAT) was set up by the manufacturer. Based on the early real-world experience, the new C3 delivery system offers advantages in terms of device repositioning resulting in high deployment accuracy [29-31]. The one-year results of the 400 patients enrolled in the European multicenter, post-market registry were as follows [29].

●Technical success was achieved in 396/400 patients (99 percent). Two patients required open conversion intraoperatively, one for iliac rupture, and the other because the stent-graft was pulled down during a cross-over catheterization in an angulated anatomy.

●Graft repositioning occurred in 192/399 patients (48.1 percent), most frequently for level readjustment with regard to the renal arteries, and less commonly for contralateral gate reorientation. Final intended position of the stent-graft below the renal arteries was achieved in 96.2 percent of patients. Two patients required an unplanned chimney renal stent to treat partial coverage of the left renal artery because of upward displacement of the stent-graft.

●Early reintervention (≤30 days) was required in two patients (0.5 percent). Late reintervention (>30 days) was required in 26 patients (6.5 percent). Estimated freedom from reintervention at one year was 95.2 percent (95% CI 92.3 to 97 percent) and at two years was 91.5 percent (95% CI 86.8 to 94.5 percent). Mean follow-up was 15.9 months (range 0 to 37).

The FDA has granted regulatory approval for the new Gore Excluder conformable AAA endoprosthesis with Active Control system. This delivery system features angulation control, giving the option to angle the device to achieve orthogonal placement to the aortic blood flow lumen to maximize conformability and seal. The data submitted to the FDA included 100 percent technical success, 100 percent freedom from device-related serious adverse events, and 100 percent patency [32]. There were no Type I or III endoleaks detected at 1-month, 6-month, or 12-month follow-up CT scans. There were no stent fractures, device migrations (10 mm or more), AAA ruptures, or conversions to open surgical repair observed. There were no aneurysm-related deaths within the 12-month follow-up, and freedom from aneurysm-related mortality was 100 percent through one year, and 98.6 percent of patients showed freedom from aneurysm enlargement. The two study arms included a short neck arm, which consisted of subjects with AAA having aortic neck angulation ≤60° and an infrarenal aortic neck length ≥10 mm; and a high neck angulation arm, which included patients with AAAs having aortic neck angulation >60° and ≤90° and infrarenal aortic neck length ≥10 mm. The data were from the first substudy of the clinical trial, which enrolled 80 patients with an aortic angle of ≤60° who completed one-year follow-up. The second substudy of the trial will evaluate the device in proximal aortic neck angles of >60° to 90° and aortic neck lengths of 10 mm or greater. Enrollment in this substudy is ongoing.

Conformable graft — The Gore Excluder Conformable graft with active control system was designed to treat more challenging AAA anatomy with a short aortic neck down to 10 mm, high neck angulation up to 90°, and a small-diameter aortic neck down to 16 mm. This next-generation endograft is engineered with the capability of actively angulating and "conforming" the proximal end of the graft to the native aortic anatomy before final deployment. This graft is available in Europe but is under trial in the United States with an estimated study completion date in 2024 (NCT02489539).

Incraft — Incraft (table 1) is an ultra-low profile (14-French [Fr, 4.7 mm]) tri-modular, bifurcated graft stent-graft system [33-37]. Initial studies show satisfactory clinical outcomes and device durability, and the potential for this ultra-low-profile design to broaden the patient population eligible for endovascular aneurysm repair [35]. The Incraft System is available for use outside the United States.

The Incraft pivotal trial (INNOVATION) enrolled 60 patients with asymptomatic AAA at six centers in Europe from March 2010 to June 2011 [33,38]. Percutaneous access was used in 60 percent of patients. The main inclusion criteria were a proximal aortic neck of ≥15 mm in length and up to 27 mm in diameter, iliac landing zones >10 mm in length and between 9 and 18 mm in diameter, an access vessel large enough to accept the 14-Fr outer diameter of the delivery system, and an aortic bifurcation >18 mm in diameter. The primary safety endpoint (absence of a type I, III, or IV endoleak or a device- or procedure-related major adverse event at the one-month follow-up) was achieved in 56 of 59 patients (97 percent) [38]. In total through two years, three patients required a postprocedure intervention, two to repair a type I endoleak and one for limb occlusion. One patient died within one year due to sepsis unrelated to the aneurysm repair. At two years, 52 patients were available for follow-up, all were free from AAA enlargement, and there were no type I or type III endoleaks [33]. There were no device- or procedure-related deaths; all-cause mortality at two-year follow-up was 11.5 percent. This graft is approved for use in Europe, the Middle East, and Africa. Although the device was approved for marketing in the US in 2018 after a favorable review of clinical data from the pivotal INSPIRATION trial (ClinicalTrials.gov Identifier: NCT01664078), the Incraft is not being manufactured.

Treovance — The Treovance (TREO) Abdominal Stent-Graft System was approved for use in the US on May 4, 2020. It has a three-piece design featuring in situ limb adjustability and a dual proximal fixation and lock stent technology. It provides both suprarenal and infrarenal fixation, distributing stent-graft fixation to two different anatomical levels, which may reduce potential migration.

The global, multicenter RATIONALE registry (ClinicalTrials.gov; identifier NCT03449875) prospectively enrolled 202 patients (mean age 73 years) with AAAs suitable for Treovance repair [39]. Technical success was 96 percent (194/202). There was no 30-day mortality and a 1 percent incidence of major morbidity (one myocardial infarction and one bowel ischemia). At one year, clinical success was confirmed for 194 (96 percent) patients. Among the eight others, six had new/persistent endoleaks and two had aneurysm expansion without identified endoleak. Eight reinterventions (4 percent) were required during the mean 13.7 months of follow-up. At one year, the Kaplan-Meier estimate for freedom from reintervention was 95.6 percent (95% CI 91.4 to 97.8 percent). Other estimates were 95.5 percent (95% CI 91.7 to 97.6 percent) for freedom from endoleak type I/III and 97.4 percent (95% CI 94.2 to 98.9 percent) for freedom from aneurysm expansion. Thirteen (6.4 percent) patients died; no death was aneurysm related.

Zenith Flex — The Zenith Flex abdominal endograft (table 1) is a bifurcated, modular, three-component system. It is composed of woven polyester (ie, Dacron) sutured to stainless steel Gianturco Z-stents, with a bare suprarenal stent for active fixation of the proximal graft. A low-profile device (available in Europe and Canada) is still under investigation and not approved for use in the United States where the clinical trial completed enrollment in January 2021. (See 'Investigational devices' below.)

The main body is available in diameters that range from 22 to 36 mm and lengths that range from 82 to 149 mm [40]. The iliac limbs are available in 8- and 24-mm diameters in lengths ranging from 3.7 to 12.4 cm. The Zenith Spiral-Z AAA iliac leg graft, which is a continuous, spiral nitinol stent designed to improve conformability and to resist kinking and migration, is available with distal diameters ranging from 9 to 24 mm in lengths ranging from 3.9 to 12.2 cm.

The delivery sheath for bifurcated grafts is between 18 and 20 French (6.0 to 7.67 mm) depending upon the size of the graft, and the sheaths for other components range from 14 to 16 French (3.67 to 5.33 mm).

The safety and efficacy of the Zenith abdominal endograft was evaluated in a comparison study involving 352 patients in four study groups: an open surgical control group, a standard-risk (SR) group, a high-risk group, and a roll-in group [41]. Eighty control patients were enrolled with the intent of comparing them with the standard repair endovascular group. The technical success rate for endovascular repair was 99.7 percent. Perioperative (30-day) morbidity (cardiac, pulmonary, renal) was significantly decreased compared with the control group. Endovascular repair was also associated with fewer transfusion requirements, diminished blood loss, shorter length of hospital and intensive care unit stay, and quicker return to daily activities. Perioperative (30-day) mortality was significantly lower in the endovascular repair group (0.5 versus 2.5 percent) compared with the open surgical group. At one year of follow-up, all-cause mortality was not significantly different between the groups (3.5 percent in the standard risk endovascular repair group versus 3.8 percent in the control group). There were no significant differences in all-cause mortality or aneurysm-related death between the standard risk endovascular group and the control group on Kaplan-Meier analysis.

There were no immediate conversions reported, but three late conversions were performed: one for endoleak, one for a rapidly expanding supraceliac pseudoaneurysm, and one for rupture at 222 days postoperatively. The need for reintervention was significantly higher (11 versus 2.5 percent) for the standard risk endograft group compared with the control group at one year follow-up. The incidence of endoleak (mostly type II) was 7.4 percent at 12 months and 5.4 percent at 24 months. Migration was not seen in any patient after 12 months. At two-year follow-up, the majority of the aneurysms demonstrated shrinkage of the aneurysm sac. In a retrospective review evaluating outcomes of 282 patients over an average of 40 months, aneurysm-related mortality was 0.7 percent [42]. Among those who required reintervention, 82 percent were performed within the first four years of endovascular repair; no new complications were treated after six-year follow-up.

Long-term outcomes were reported in a study of 610 repairs with a mean follow-up of 99.2 months (range 0 to 175 months). Overall survival was 24 percent at 14 years. Failure of the aneurysm repair occurred in 132 (21.6 percent) of patients at 14 years. On multivariate analysis, independent predictors of EVAR failure included type I and III endoleak (hazard ratio [HR] 6.7; 95% CI 4.6-9.7), type II endoleak (HR 2.3; 95% CI 1.6-3.4), and American Society of Anesthesiologists (ASA) grade 4 (HR 1.6; 95% CI 1.0-2.6) [43].

Later series reporting on the long-term outcomes following EVAR with the Zenith endograft also showed a high rate of late failures and reinterventions at 10 years or later following EVAR, with a freedom from any stent-graft-related complications of 52 percent, and freedom from graft-related reinterventions of 70 percent at 16 years [44]. In another series with long-term outcomes, freedom from late reintervention and open surgical conversion at 1, 3, 5, and 10 years was 98.9, 88.9, 86.7, and 57.9 percent, respectively [45].

The outcomes using the Zenith Spiral-Z iliac leg graft were reported from a large multicenter post-marketing study, the Spiral-Z registry [46]. In 599 treated patients, 13 (2 percent) underwent 15 limb-related reinterventions (7 for occlusions and 8 for nonocclusive causes). In one patient, a distal type I endoleak and device migration (>10 mm) involving a right iliac leg was noted at the 12-month follow-up visit.

WITHDRAWN/INVESTIGATIONAL DEVICES

Investigational devices — Emerging technologies continue to focus on improving the ease of delivery of the device. Advanced graft designs (fenestrated, branched) that are investigational are discussed below. (See 'Advanced devices' below.)

Low profile (LP) devices include the 18-French (6-mm) Zenith LP device and 18-French (6 mm). Preliminary experiences have documented early safety and efficacy with technical success rates of 90 to 100 percent [38,47]. The Zenith LP study completed enrollment in the US in 2021, but FDA approval was not sought given the high incidence of limb occlusion seen in the Canadian and European experience [48]. Testing of a new LP graft design is anticipated in another clinical trial.

Other emerging technologies include the introduction of flexible repositionable devices that might be useful in patients with high-risk anatomy. The Anaconda graft combines such features, and the safety and short-term efficacy of the device have been reported [49]. The Nellix device discussed below has a unique sealing system.

Nellix — The Endologix Nellix Endovascular aneurysm sealing system is a unique endograft system that uses right and left graft limbs that are placed simultaneously into the neck of the aneurysm as balloon-expandable kissing stent-grafts. Associated "endobags" are filled with a biocompatible polymer that conforms to the contour of the aneurysm sac to exclude the aneurysm and seal the AAA, introducing the concept of endovascular aneurysm sac sealing (EVAS) [50]. The pivotal trial included 150 patients with a mean AAA diameter of 5.8 cm [51]. Technical success was 100 percent. At 30 days, five major adverse events were reported, including one death from multisystem organ failure, one patient with bowel ischemia, one with respiratory failure, and two with renal failure. One early reintervention was performed, and at 30 days, nine endoleaks (6 percent) were identified on follow-up computed tomography (CT; one type I, eight type II). Mid-term follow-up has identified unresolved endoleaks in 1.3, 0.7, 2.7 and 0 percent of patients for endoleak types IA, IB, II, and III, respectively [52]. However, data from publications of this device have raised concerns that outcomes are suboptimal when the system is used outside current instructions for use, leading the company to restrict its use only under a clinical protocol with prescreened patients who adhere to the current indications. The EC Certificate of Conformity (CE Mark) for the Nellix EndoVascular Aneurysm Sealing System (Nellix System) was suspended by its Notified Body, G-MED, following a voluntary recall and Field Safety Notification (FSN) issued by Endologix on January 4, 2019. An investigational device exemption (IDE) approval from the FDA was granted to conduct a pivotal study to evaluate the safety and effectiveness pf the Nellix Chimney EndoVascular Aneurysm Sealing System (chEVAS). The IDE trial will combine the Nellix endograft with parallel visceral stents to treat patients with juxtarenal, pararenal, and suprarenal AAA.

Withdrawn/recalled devices — Several devices introduced for endovascular repair of abdominal aortic aneurysm (AAA) have been withdrawn or recalled from the market, were not used clinically, or are still awaiting approval after the initial trial data. The most important of these were the Ancure, AneuRx, and Talent grafts. Other devices that are no longer available include the Lifepath device, which had problems with stent fractures, and the Fortron and Quantum grafts, which were redesigned into the Incraft device.

●Ancure – The Ancure graft was a flexible, unsupported fabric graft with active fixation at the ends of the graft using wire hooks that penetrated the aortic wall. The graft was approved for use in the United States in 1999 but was recalled in 2001. Production of the graft was suspended in 2003 due to device malfunctions and adverse events associated with device deployment.

●AneuRx – The AneuRx graft is no longer manufactured; it has been replaced by the manufacturer by the Endurant graft (table 1). The device was a modular, bifurcated graft of woven polyester sutured to and supported by a self-expanding nitinol exoskeleton introduced in 2008 with later alterations to the delivery system [53].

●Talent – The Talent abdominal stent-graft is no longer manufactured. The manufacturer provides the Endurant graft in its place. The Talent graft was a modular, bifurcated graft composed of a woven polyester fabric with an external self-expanding support structure of M-shaped nitinol stents. The proximal graft has an uncovered stent for aortic fixation [54].

●AFX and Powerlink – The AFX system was replaced by the AFX2 system by the manufacturer in 2016. The original Powerlink graft [55] evolved into the AFX system, which was distinguished by a lower profile and a multilayered STRATA ePTFE graft material that was intended to provide greater strength and better conformability. The STRATE ePTFE graft material was replaced by DURAPLY ePTFE in the AFX2 system.

●Ovation – The Ovation iX endograft system, which was an ultra-low profile (14-French [Fr; 4.7 mm]) system, was recalled by the manufacturer (Endologix) in May, 2020. It is being replaced by the manufacturer with the Alto graft. The main body of the ovation graft was a modular, two-docking-limb device with active suprarenal fixation and polymer-filled proximal fixation rings. Short-term outcomes showed that the device was safe and effective for treating patients with infrarenal AAA, particularly among those with challenging anatomy including short aortic necks and narrow iliac vessels [56-64]. However, the manufacturer sent notice to customers informing them of the risk of polymer leak during the polymer fill step of the index implantation procedure. This event could be associated with an acute hypersensitivity response to liquid polymer and manifest as systemic hypotension during the procedure. Other device-related findings that were indicative of a polymer leak include complete emptying of the fill polymer syringe, and incomplete filling of the polymer channels. The presumed polymer leak rate was cited as 0.86 percent over the lifetime distribution of the device. The device has since been voluntarily recalled (class I recall US Food and Drug Administration).

EVAR RANDOMIZED TRIALS — Several trials have compared endovascular aneurysm repair using a variety of endografts to open surgical repair for the treatment of infrarenal abdominal aortic aneurysm (AAA) [65-72].

●The devices used in the Dutch Randomized Endovascular Aneurysm Management (DREAM) trial included the Zenith in 35 percent of EVAR patients, Talent in 28 percent, AneuRx in 7 percent, Excluder in 21 percent, and other devices in the remaining 10 percent [65].

●The endografts used in the EVAR1 and EVAR2 trials included Zenith in 51 percent, Talent in 33 percent, Excluder in 7 percent, AneuRx in 4 percent, and Quantum in 3 percent [68-70].

●Devices used in the OVER trial included the Excluder in 37 percent, Zenith in 39 percent, and AneuRx in 21 percent [71].

These trials have consistently demonstrated significantly reduced perioperative morbidity and mortality (1 to 2 versus 3 to 5 percent) for endovascular compared with open surgical repair; however, long-term mortality is not significantly different. Endovascular repair is associated with a significantly greater number of graft-related secondary interventions, but the overall need for reintervention may be similar when all open surgical complications (eg, hernia, adhesiolysis for small bowel obstruction) are taken into account. The details of these trials and factors that enter into the decision to offer open versus endovascular management of elective and ruptured AAA repair are discussed elsewhere. (See "Management of asymptomatic abdominal aortic aneurysm", section on 'Open versus endovascular aneurysm repair' and "Surgical and endovascular repair of ruptured abdominal aortic aneurysm", section on 'Open surgical versus endovascular repair'.)

ADVANCED DEVICES — When aortic disease is more extensive and involves branch vessels, the complexity of the repair and risk of complications increases. Approaches to manage more complicated anatomy include debranching procedures and the use of fenestrated and branched endografts.

Debranching procedures involve ligation of an aortic branch that will be covered by the endograft and surgical revascularization (eg, carotid-subclavian bypass, hepatorenal bypass). The role of debranching in the treatment of aneurysmal disease is discussed elsewhere. (See "Endovascular repair of abdominal aortic aneurysm", section on 'Advanced devices and techniques'.)

Fenestrated grafts — The use of fenestrated-endovascular aneurysm repair (FEVAR) to manage more challenging aortic anatomy continues to evolve [73-88]. Fenestrated and branched grafts are available for clinical use in Europe but are considered investigational devices in the United States and are still undergoing clinical trials. The Zenith Fenestrated (ZFEN) AAA Endovascular Graft is the most studied device. Several other device manufacturers are currently working on off-the-shelf designs of branched and fenestrated grafts with clinical trials underway.

The ZFEN device is similar in construction to the Zenith device discussed above with the addition of fabric openings (fenestrations) created in the graft based upon measurements obtained with high-resolution computed tomographic (CT) angiography. These grafts have been used primarily to manage juxtarenal AAAs.

A systematic review identified 11 studies describing a total of 660 procedures [87]. Initial success in placing the graft was >99 percent. Target vessel perfusion ranged from 90.5 to 100 percent. Double fenestrations were more common than triple or quadruple fenestrations. The perioperative (30-day) mortality rate was 2 percent.

The largest of these studies evaluated the outcome of 134 patients following repair of juxtarenal abdominal aortic aneurysm treated with a ZFEN AAA Endovascular Graft at 16 French centers between May 2004 and January 2009 [77]. A total of 403 visceral vessels were perfused through a fabric fenestration, including 265 renal arteries. The technical success of graft placement was 99.3 percent with one patient requiring open conversion. The success of target vessel revascularization was 99 percent. Perioperative mortality (30-day) was 2 percent. Dialysis was required in 4 percent of patients (transient in 3 percent and permanent in 1 percent). Endoleaks occurred in 12 percent of patients prior to discharge (one each type I and type III endoleak). Three patients had sac enlargement within the first year, associated with a persistent endoleak. No aneurysms ruptured or required open conversion during the follow-up period.

During follow-up, four renal artery occlusions were detected. A total of 12 procedure-related reinterventions were performed in 12 patients during follow-up, including 6 to correct endoleaks and 5 to correct threatened visceral vessels. Longer-term mortality was 9 percent over the follow-up period, but none of the deaths were related to the aneurysm repair. Actuarial survival at 12 and 24 months were 93 and 86 percent, respectively. Aneurysm sac size decreased >5 mm in 52, 66, and 75 percent of patients at one, two, and three years, respectively.

Another study evaluated renal outcomes in 67 patients treated by FEVAR with 134 matched controls who underwent standard infrarenal aortic endografting [89]. There were no significant differences in the incidence of a greater than 25 percent decline in estimated glomerular filtration rate (eGFR) at two years and five years. Progression to stage IV to V chronic kidney disease was also similar at two years and five years, with similar serum creatinine and eGFR up to five years. The rate of progression to renal failure requiring dialysis was low and similar in both groups (1.5 percent). However, there were significantly more renal artery stenosis/occlusions (15/67 [22 percent] versus 3/134 [2 percent]) and renal-related reinterventions (12/67 [18 percent] versus 4/134 [3 percent]) in patients treated by FEVAR.

FEVAR appears to have similar outcomes compared with standard, open infrarenal AAA repair and improved outcomes compared with complex, open AAA repair. A review of the American College of Surgeons National Surgical Quality Improvement Program targeted vascular module identified 181 open, complex AAA repairs with 220 ZFEN repairs [90]. Compared with ZFEN, open, complex AAA repair was associated with higher risk of perioperative mortality (odds ratio [OR] 4.9, 95% CI 1.4-18), postoperative renal dysfunction (OR 13, 95% CI 3.6-49), and overall complication rates (OR 4.2, 95% CI 2.3-7.5). Compared with standard, infrarenal EVAR, ZFEN had comparable rates of perioperative mortality (1.8 versus 0.8 percent), renal dysfunction (1.4 versus 0.7 percent), and any complications (11 versus 7.7 percent). There was no significant difference for perioperative mortality, postoperative renal dysfunction, or any complication between infrarenal EVAR and ZFEN.

Branched grafts — Branched grafts have a separate smaller side-arm graft sutured to the basic endovascular graft for deployment into a vessel to preserve flow into it. Another approach places a self-expanding stent-graft through the opening of a fenestrated graft. The ZFEN AAA Endovascular Graft is the primarily studied device. (See 'Fenestrated grafts' above.)

Branched abdominal aortic grafts have been used in patients with suprarenal and juxtarenal aortic aneurysms, and common iliac artery aneurysms [91]. Initial experience with branched aortic grafts has shown similar perioperative mortality as conventional endovascular repair, but the rate of aneurysm-repair-related mortality may be higher. They are only available as part of clinical trials or an Investigational Device Exemption; they are not commercially available in the US.

Branched grafts to the visceral vessels allow endovascular repair of more extensive aortic disease. The use of visceral branch devices in endovascular repair of abdominal aortic aneurysm is discussed elsewhere. (See "Endovascular repair of abdominal aortic aneurysm", section on 'Advanced devices and techniques'.)

Iliac branched grafts are intended to preserve flow into the internal iliac artery during endovascular repair (abdominal aortic aneurysm or iliac artery aneurysm) that requires extension beyond the internal iliac artery orifice. The PRESERVE study evaluated the safety and efficacy of the Zenith Iliac Branch Device. The Gore Excluder Iliac Branch Endoprosthesis is the first off-the-shelf aortic branch solution approved in the United States and is fully designed to preserve blood flow to external and internal iliac arteries. The use of iliac branch devices is discussed in detail elsewhere. (See "Surgical and endovascular repair of iliac artery aneurysm", section on 'Branched grafts'.)

CHOICE OF DEVICE — There are no trials comparing specific aortic endografts for the treatment of abdominal aortic aneurysm (AAA). However, although the primary comparison in the endovascular aneurysm repair trials was between endovascular and open surgical repair, comparisons between the Talent and Zenith devices in the EVAR trials failed to find significant device-specific differences [92]. (See "Management of asymptomatic abdominal aortic aneurysm", section on 'Open versus endovascular aneurysm repair'.)

Comparisons between different grafts have also been made in observational studies. One study that included 703 patients who underwent endovascular abdominal aortic aneurysm repair at a single institution over a six-year period found no significant differences for important outcomes. The devices used were Ancure (no longer available), AneuRx, Excluder, Talent, and Zenith. The outcomes included aneurysm-related death, conversion to open repair, need for secondary intervention, device migration, freedom from aortic rupture, and detection of type I or III endoleaks [93]. Adhering to the device manufacturer's criteria for anatomic suitability appears to be the more important issue. (See "Complications of endovascular abdominal aortic repair", section on 'Endograft-related complications'.)

Because the graft design does not appear to have a major impact on outcomes of straightforward endovascular aneurysm repair, most operators choose one endograft for routine use, reserving others for one or more features that might be more suited to a specific patient anatomy [92,93]. The operator should become familiar with specific advantages inherent to endograft designs (table 1). A device with a lower profile is more advantageous in the patient with narrow access vessels, whereas a device with better conformability and active fixation would be more helpful in the patient with challenging aortic neck anatomy.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Aortic and other peripheral aneurysms".)

SUMMARY AND RECOMMENDATIONS

●Endovascular repair with abdominal endograft devices is used primarily to treat infrarenal abdominal aortic aneurysm. Endovascular aortic repair requires that specific anatomic criteria be fulfilled, and, for those with appropriate anatomy, this technique has become a preferred approach and allows the treatment of patients who might not otherwise be candidates for aortic repair. (See 'Introduction' above.)

●Endovascular aortic repair involves the insertion of endovascular graft components, usually via a femoral approach. The endovascular graft modular components are built in vivo by the delivery and deployment of these components in an established order. Upon deployment, the endograft expands, contacting the aortic wall proximally and aorta or iliac vessels distally to exclude the native, dilated portion of the aortic wall from aortic blood flow and pressure. (See 'Basic principles' above.)

●Although there are significant variations in endovascular graft design, three types of components are common to all: the delivery system, main body device, and device extensions. Devices that are commercially available in the United States to treat the abdominal aorta include the AFX2, Alto, Aorfix, Endurant, Excluder, Incraft, Treovance, and Zenith Flex. The characteristics for each graft are described above. (See 'Abdominal devices' above.)

●When aortic disease is more extensive and involves branch vessels, the complexity of the repair and risk of complications increases. Approaches to manage more complicated anatomy include debranching procedures and the use of fenestrated and branched endografts. These endografts preserve blood flow into specific aortic branches depending upon the level of repair but are available only for investigational use in the United States. (See 'Advanced devices' above.).

●Several trials have compared endovascular aneurysm repair with open surgical repair using a variety of endografts for the treatment of infrarenal abdominal aortic aneurysm. These trials have consistently demonstrated significantly reduced perioperative (30-day) morbidity and mortality (1 to 2 versus 3 to 5 percent) for endovascular compared with open surgical repair; however, long-term mortality is not significantly different. Secondary intervention is frequently needed in patients who receive an abdominal endograft. As such, these devices require lifelong surveillance; the long-term outcomes for these devices continue to be studied. (See 'EVAR randomized trials' above.)

●The few comparisons that are available for specific endograft designs for the treatment of abdominal aortic aneurysm have found no significant differences between devices for important outcomes. Because the graft design does not appear to have a major impact on the outcomes of straightforward endovascular aneurysm repair, most operators choose one endograft for routine use, reserving others for one or more features that might be better suited to a specific patient. (See 'Choice of device' above.)