Endovascular devices for thoracic aortic repair

INTRODUCTION — Thoracic endovascular aortic repair (TEVAR) has become the first-line intervention for a variety of aortic pathologies due to reduced perioperative morbidity and mortality compared with open surgical repair [1]. The year 2022 marked the 30th anniversary of the first TEVAR performed in the United States for the treatment of a descending thoracic aortic aneurysm [2]. Following initial experience with endovascular aneurysm repair, TEVAR was rapidly adopted and is now the primary treatment strategy for nearly every pathology involving the descending thoracic aorta including type B aortic dissection, blunt traumatic aortic injury, intramural hematoma, and penetrating aortic ulcer [1,3].

Endovascular aortic repair requires that specific anatomic criteria be fulfilled, and, for those with appropriate anatomy, this technique allows the treatment of patients who might not otherwise be candidates for aortic repair. Advanced endovascular aortic devices, which allow flow into specific aortic branches depending upon the level of repair (eg, innominate, left subclavian, renal artery, internal iliac artery), are available to treat more complex anatomy.

The placement of aortic endografts is associated with device-related complications that can include component disconnection, stent-graft buckling, and migration over time often due to disease progression (eg, aortic dissection). In the thoracic aorta, secondary intervention is needed in 10 to 60 percent of patients, more commonly in patients undergoing endovascular repair of thoracic dissection and more complicated hybrid repairs [4-6]. As such, these devices require lifelong surveillance; the long-term outcomes continue to be studied.

The specific devices available for endovascular repair of the thoracic aorta will be reviewed here. The indications for, placement of, and complications of these devices are discussed elsewhere. (See "Endovascular repair of the thoracic aorta" 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 it curves, forming the aortic arch, and descends caudally adjacent to the spine. The ascending thoracic aorta gives off the coronary arteries. The aortic arch branches are typically the brachiocephalic trunk (branches to the right common carotid and right subclavian arteries), left common carotid, and left subclavian arteries; however, aortic arch anatomy is variable (figure 1).

The descending thoracic aorta provides paired thoracic arteries (T1-T12) and continues through the hiatus of the diaphragm to become the abdominal aorta, which extends retroperitoneally to its bifurcation into the common iliac arteries at the level of the fourth lumbar vertebra (figure 2). The abdominal aorta lies slightly left of the midline to accommodate the inferior vena cava, which is in close apposition. The branches of the aorta (superior to inferior) 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, left and right internal spermatic arteries, inferior mesenteric artery, left and right common iliac artery, middle sacral artery, and the paired lumbar arteries (L1-L4).

The common iliac artery bifurcates into the external iliac and internal iliac arteries at the pelvic inlet (figure 3). The internal iliac artery gives off branches to the pelvic viscera and also supplies the musculature of the pelvis. The external iliac artery passes beneath the inguinal ligament to become the common femoral artery [7].

BASIC PRINCIPLES — Endovascular aneurysm repair refers to the insertion of endovascular graft components, usually via a femoral approach. A thoracic endograft is constructed by the delivery and deployment of these components in an established order in vivo (figure 4). Upon deployment, the thoracic endograft self-expands, contacting the aortic wall proximally and distally excluding the native aortic wall from aortic blood flow and pressure.

Although there are significant variations in endovascular graft design, three types of components are common: the delivery system, the main device, and device extensions.

Delivery system — Thoracic endografts are typically delivered through the femoral artery, percutaneously or by direct surgical cutdown. The size of the delivery system varies depending upon the diameter of the device that is needed to provide proper endograft fixation.

If the femoral or iliac artery is too small to accommodate the delivery system, access can be obtained by direct puncture of the iliac artery or aorta through a retroperitoneal incision or by suturing a synthetic graft to the iliac artery (ie, iliac conduit). An alternative method creates an endovascular conduit by first lining the iliac artery with a covered stent and then allowing a contained rupture of the diseased iliac segment as the endograft is passed through.

Main device — The main thoracic endograft device is straight or tapered, and two distinct device components are often used (eg, straight graft proximally, tapered graft distally). Endovascular grafts rely primarily upon tension in the proximal graft to maintain the positioning of the graft. Fixation systems may include barbs or uncovered proximal stents.

Extensions — One or more extension devices (proximal or distal) may be needed to provide a complete seal. Following the deployment of the main device, an aortogram is performed to assess for endoleak. If additional ballooning of the device does not firmly appose it to the aortic wall and eliminate a type I endoleak (figure 5), placement of additional proximal or distal aortic extensions may be needed.

THORACIC DEVICES — The indications for endovascular treatment of thoracic aortic pathologies are broadening. Although thoracic endovascular aortic repair was developed for the treatment of degenerative aneurysmal disease, other pathologies can be treated using these devices, including aortic dissection, aortic transection, intramural hematoma, and penetrating aortic ulcer [1,3].

Endovascular aortic repair requires that specific anatomic criteria be fulfilled, and, for those with appropriate anatomy, this technique allows for the treatment of patients who might not otherwise be candidates for thoracic aortic repair. Advances in endograft design have allowed for the treatment of patients with increasingly complex anatomy, but different graft designs and manufacturers may be needed depending on the pathology and anatomy involved. Thus, it is not surprising that a number of thoracic stent-graft devices are commercially available and the design of the available grafts is ever-evolving to address problems that are frequently encountered with the delivery, deployment, and fixation of thoracic endografts [8].

Controlled comparisons of the various thoracic endografts have not been performed [9]. Data supporting the use of these devices are primarily from clinical trials performed to seek approval from the US Food and Drug Administration (FDA) or Conformité Européenne (CE) mark. Devices that are currently approved or under investigation for treatment of descending thoracic aneurysms include the Gore TAG and CTAG, Cook Zenith TX2 and Alpha, Medtronic Valiant Thoracic Stent-Graft System, Bolton Relay, TAArget, and E-Vita grafts [10]. Later-generation grafts, such as the Conformable TAG graft (CTAG) with active control, the Valiant Navion graft, and the Bolton RelayPro, have also been approved in the United States for the treatment of thoracic aortic pathology [1].

A number of investigational devices are in early phases. (See 'Investigational and withdrawn devices' below.)

The essential features of the various thoracic endografts and clinical data supporting their use are discussed below.

TAG and CTAG — The TAG device is a self-expanding tube-shaped stent-graft supported by a nitinol exoskeleton lined with expanded polytetrafluoroethylene (ePTFE) and covered with an additional reinforcing sleeve of ePTFE and fluorinated ethylene propylene (FEP), which reduces the potential for type IV endoleak (figure 5). The proximal and distal ends of the graft have scalloped flares that are also lined with graft material and an ePTFE sealing cuff at the base of each flare. A radiopaque band is located at the base of each flared end to facilitate placement under fluoroscopy. The flared sealing regions are designed to improve conformity and better apposition of the graft to the aortic wall.

The TAG device is available in diameters ranging from 26 to 45 mm in 10-, 15-, and 20-cm lengths. The delivery sheath ranges from 20 to 24 French (6.67 to 8 mm) in diameter [11]. The device is constrained within a deployment line. Once the device is positioned, the deployment line unlaces from the middle of the device toward both ends, thus avoiding a "windsock" effect. Once deployed, the device is ballooned open with a trilobed balloon that allows aortic flow during inflation.

The TAG pivotal trial compared open surgical repair with endovascular repair in patients with descending thoracic aortic aneurysm but was interrupted due to device failure [12]. After modification of the device, a multicenter study compared 51 patients treated with the TAG device with the surgical group from the pivotal study, and an additional 80 patients were enrolled as part of a confirmatory study [13]. Significantly improved aneurysm-related survival (96 versus 88 percent) was found at five years (original pivotal) and three years (confirmatory study) for patients treated with thoracic endovascular repair and a reduced incidence of major adverse events (71 versus 21 percent at 30 days, 37 versus 21 percent long-term) compared with open surgery. No device fractures were reported since the device modification consisting of removal of a longitudinal spine [14].

CTAG is intended to conform to smaller, more tortuous and/or tapered thoracic aortic anatomy. It is available in a wider range of diameters (21 to 45 mm) with a sheathless delivery system and provides treatment of pathologies that can affect nonaneurysmal (normal diameter) aortas such as blunt aortic injury, penetrating aortic ulcer, and aortic dissection [15,16]. A nonrandomized study evaluated the safety and efficacy of the CTAG device for the repair of traumatic aortic transection in 51 patients [17]. Technical success was 100 percent with no operative mortality. No major device events have been reported. Perioperative (30-day) mortality was 8 percent, which was not felt to be device or procedure related. No conversions to open repair have been reported to date. Endovascular repair for the treatment of blunt aortic injury is discussed in detail elsewhere. (See "Surgical and endovascular repair of blunt thoracic aortic injury".)

A next-generation device, the CTAG with active control, has been commercially released in the United States for the endovascular repair of aneurysms, transections, and type B dissections of the descending thoracic aorta. A smaller-diameter primary delivery sleeve gives the device and system a lower profile across 10 device sizes [15]. It provides controlled, two-stage deployment, with primary deployment to an intermediate diameter and secondary deployment to full diameter. This design allows for continuous blood flow throughout the deployment, which minimizes the windsocking effect in the thoracic aorta and allows for precise deployment. It is also designed to allow for angulation of the proximal end of the device for improved seal and apposition. This device has been available for use in Europe since 2017.

TX2 and Alpha — The Zenith TX2 endograft and Zenith Alpha are two-piece systems. The Alpha graft is a next-generation low-profile device [18,19]. The components are constructed from modified Gianturco Z-stents (stainless steel) sutured to woven polyester graft material (ie, Dacron). The graft material lines the graft and is also external to the stent structure at the proximal and distal ends of the graft to allow apposition of the graft to the aortic wall. Active fixation with external barbs at the proximal and distal aspects of the device is present for each component. Straight and tapered proximal components are available. A bare metal stent is attached to the distal graft and is similar to the suprarenal stent component of the Zenith device for endovascular repair of abdominal aortic aneurysm. The extension allows for active fixation of the device over the origins of the visceral vessels. A suture modification of the device (Pro-form) is intended to improve conformability of the graft in the aortic arch during very proximal descending thoracic aortic deployments to minimize the risk of graft infolding and collapse [20].

The proximal and distal Zenith TX2 device components are available in diameters ranging from 28 to 42 mm [21]. The components range in length from 12 to 21.6 cm [22]. The devices are delivered through a 20- or 22-French (6.67, 7.33 mm) sheath depending upon the diameter of the device. The proximal and distal Zenith Alpha device components are available in diameters ranging from 18 to 46 mm. The components range in length from 10.5 to 16.0 cm. The devices are delivered through a 16- to 20-French (6.0 to 7.7 mm) sheath depending upon the diameter of the device.

These devices are constrained with several trigger wires that are released sequentially once the device is positioned. After deployment, the device is self-expanding; subsequent ballooning is an option. The safety and effectiveness of the Zenith TX2 was evaluated in a multicenter study of 230 patients with descending thoracic aortic aneurysms or thoracic aortic ulcers who were treated with endovascular repair using the TX2 (n = 160) or open surgery (n = 70) [23]. Perioperative (30-day) mortality was not significantly different between the groups; however, perioperative morbidity was lower for endovascular repair (composite index 1.3 versus 2.9). Although endovascular repair was associated with fewer cardiovascular, pulmonary, and vascular adverse events, the incidence of neurologic events was not significantly different. At 12-month follow-up, aneurysm growth was identified in 7.1 percent of endovascular patients, endoleak in 3.9 percent, and migration >10 mm in 2.8 percent. In another study of patients considered at high risk for open surgery, the TX2 graft was used to treat primarily thoracic aneurysms in 100 patients [24]. The overall mortality was 17 percent, and aneurysm-related mortality was 14 percent. Secondary interventions were needed in 15 percent of patients. Stroke and paraplegia rates were 3 and 6 percent, respectively. Stent migration occurred in 6 percent of patients at one-year follow-up.

The durability of the Zenith Alpha graft for the treatment of thoracic aneurysms and penetrating ulcers has been reported [25]. Seventy consecutive patients were treated and had a computed tomography (CT) follow-up at one year or later. Ongoing clinical success, the primary endpoint, was 87.1 percent. There were three cases of type IA endoleak (4.3 percent), two cases of type IB endoleak (2.9 percent), and one case of aneurysm sac enlargement (1.4 percent). Five patients died postoperatively (7.1 percent). No type III or type IV endoleak was detected; there was one case of distal stent-graft migration and no stent fracture. Reintervention was necessary in one case (1.4 percent) for a combined type IA and type II endoleak. There were no conversions to open repair and no ruptures or intraoperative deaths. All-cause mortality was 17.1 percent at 76 months. The authors concluded that the Zenith Alpha Thoracic Stent Graft appears to maintain favorable results in a longer time frame with a low incidence of aneurysm sac expansion or migration.

The Zenith TX2 dissection system is designed to treat acute complicated type B aortic dissection. It is a two-component system composed of a proximal TX2 graft combined with a distal bare stainless steel Z-stent. The proximal component covers the entry tear, and the bare stents are intended to expand the true lumen while allowing flow to branch vessels (ie, PETTICOAT technique). The bare stent can be deployed to the aortic bifurcation, if needed. The distal stent is available in 8.2-, 12.3-, and 16.4-cm lengths and a single 46-mm diameter that accommodates aortic diameters from 24 to 38 mm.

The safety and effectiveness of the Zenith TX2 dissection system was evaluated in a multicenter study of 40 patients in which the indications for enrollment included branch vessel malperfusion, impending rupture, aortic diameter ≥40 mm, rapid aortic expansion, and persistent pain or hypertension despite maximum medical therapy [26]. Most patients (31/40) were treated for impending aortic rupture or branch vessel malperfusion. The mean time from symptom onset to treatment was 20 days (range, 0 to 78 days). Seven different combinations of stent-grafts and dissection stents were used. The perioperative (30-day) mortality rate was 5 percent, and one-year survival rate was 90 percent. Perioperative morbidity included stroke (7.5 percent), transient ischemic attack (2.5 percent), paraplegia (2.5 percent), retrograde progression of dissection (5 percent), and renal failure (12.5 percent). None of the patients with renal failure became dialysis dependent. Favorable aortic remodeling was observed during the course of follow-up, and completely thrombosed thoracic false lumen was observed in 31 percent of patients [27,28].

The safety and efficacy of the Zenith Alpha graft, which is available in smaller graft diameters (starting at 18 mm) and lower-profile delivery systems (starting at 16 F) than currently available thoracic endografts, was evaluated in a prospective, nonrandomized study at 10 sites [29]. Eligible patients with blunt thoracic aortic injuries (BTAIs; grade II to grade IV) in the descending thoracic aorta were treated with the Zenith Alpha device. The device (nitinol stents and polyester graft material) accommodates a tighter aortic curvature (radius of 20 mm) than the predicate Zenith TX2 Pro-Form. Follow-up clinical and imaging evaluations were performed at 30 days, at 6 and 12 months, and annually thereafter through five years. Technical success was achieved in all 50 patients, and device access was entirely percutaneous in 22 patients (44 percent). Smaller-size grafts (18 to 24 mm) were used in 15 patients (30 percent). There was no intraoperative mortality, but there was one death within 30 days, which was not device related. One patient experienced a stroke of undetermined cause seven days after the procedure, and one patient underwent reintervention for a site-reported proximal type I endoleak (core laboratory reported unknown endoleak type) at 30 days after the procedure. There have been no conversions to open surgical repair, paraplegia, or aortic rupture within 30 days. The authors concluded that the short-term results indicate that the Zenith Alpha thoracic endovascular graft appears safe and effective for the treatment of BTAIs. This low-profile device enables complete percutaneous repair in a large percentage of patients and can achieve high rates of technical success and very low rates of aortic injury-related mortality within 30 days. (See "Surgical and endovascular repair of blunt thoracic aortic injury".)

Valiant — The Valiant Thoracic Stent-Graft System is a third-generation device based upon the earlier Talent Thoracic Stent-Graft System. The Valiant graft has a modified proximal bare stent with eight shorter bare stents proximally. The longitudinal support bar of the earlier Talent device was removed to provide improved device flexibility for the Valiant device. A later generation device, the Valiant Navion, which was introduced but subsequently removed from the market, is discussed below. (See 'Valiant Navion graft' below.)

The graft is available in straight or tapered configurations with diameters ranging from 24 to 46 mm and lengths up to 22.7 cm. The device is also delivered through the Xcelerant delivery system.

The initial experience of the Valiant endograft was reported in a multicenter retrospective study of 180 patients [30]. A variety of indications were treated, including thoracic aneurysms (n = 66), thoracoabdominal aneurysms (n = 22), acute aortic syndrome (n = 19), aneurysm degeneration of chronic aortic dissection (n = 52), and traumatic aortic dissection (n = 21). The perioperative (30-day) mortality for the series was 7.2 percent with perioperative morbidity that included stroke in 3.8 percent and paraplegia in 3.3 percent. Mortality rates differed significantly depending upon indications, with the highest rate for thoracoabdominal aneurysms at 27.3 percent and lowest (none) for acute traumatic rupture.

The VALOR II study has been completed using the Valiant stent-graft, resulting in approval of the Captivia Delivery System for use in the United States [31]. Commercial release is ongoing, and the one-year results demonstrate safety and efficacy comparable with the earlier Talent stent-graft.

The five-year outcomes of the Evaluation of the Clinical Performance of the Valiant Thoracic Stent Graft With the Captivia Delivery System for the Endovascular Treatment of Blunt Thoracic Aortic Injuries (ie, RESCUE) have been reported [32-34]. No stroke or spinal cord ischemia were observed. No secondary endovascular procedures or conversion to open surgery were reported through five years, and complete exclusion of the traumatic injury was maintained with no incidences of stent-graft kinking, fracture, loss of patency, or migration.

Relay and Relay Pro — The Relay device is composed of self-expanding nitinol stents sutured to a polyester fabric graft with a curved longitudinal nitinol wire intended to provide longitudinal strength. It has a proximal bare stent that remains constrained until the endograft is fully deployed. The safety and efficacy of this device has been demonstrated [35,36].

The Relay device is available in straight and tapered configurations in diameters ranging from 22 to 46 mm and lengths from 10 to 25 cm. The delivery sheath ranges from 20 to 26 French (6.67 to 8.33 mm) in diameter depending upon the diameter of the device.

A study from the RESTORE registry, which is a multicenter, European, prospective clinical registry of patients who have undergone endovascular repair with the Relay device, found a technical success rate of 97.3 percent [37]. Among 150 patients evaluated, thoracic aortic aneurysm was treated in 64.7 percent of patients and dissections were treated in 19.3 percent. The perioperative (30-day) mortality rate was 10 percent. Perioperative morbidity included paraplegia in 3.3 percent, recovered paraparesis in 3.3 percent, and stroke in 0.6 percent. The reintervention rate during two-year follow-up was 8.9 percent due to two stent-graft migrations, three proximal type I endoleaks, four type III endoleaks, and five distal type I endoleaks. No open conversions were needed during follow-up.

Another study of the RESTORE registry evaluated the performance of the Relay device in 91 patients with acute or chronic aortic dissections [38]. Most patients (84 percent) had descending thoracic aortic (type B) dissection, of which 61 were classified as chronic and 30 as acute. The overall technical success rate was 95 percent. Perioperative mortality (30-day) was 8 percent with greater mortality in acute (13 versus 5 percent) compared with chronic aortic dissections. Paraplegia, paraparesis, and stroke occurred in four, one, and two patients, respectively. Type I endoleak rate occurred in 7 percent of patients. The two-year survival rate was 83 percent.

RelayPro is a low-profile, next-generation thoracic stent-graft device designed for thoracic endovascular repair in patients with smaller access vessels. The device has CE Mark approval and was launched in Europe in 2018. In the United States, the RelayPro pivotal trial has completed enrollment. The results of a prospective multicenter study of the low-profile Relay stent-graft, the Regeneration Study, reported on the European experience in patients with thoracic aortic disease [39]. A total of 31 patients with various aortic pathologies were treated between 2014 and 2015 at eight sites in Italy and Spain. Technical success was 100 percent (primary, 90 percent; assisted primary, 10 percent). Freedom from aneurysm/dissection-related mortality through 30 days was 100 percent. Freedom from device-related major adverse events through 30 days was 94 percent. At one year, there was one (3 percent) type Ib and one (3 percent) type II endoleak, one (3 percent) nonaneurysm-related late death, and one (3 percent) secondary intervention (to correct type Ib endoleak). The nonbare RelayPro device was approved for use in August of 2021 and designed for patients with small access vessels with indications to treat thoracic aortic aneurysms and penetrating atherosclerotic ulcers.

The manufacturer also launched an "Upon Request" program in January of 2022 to allow for approximately 2000 stent-graft configurations and more solutions to fit the anatomic needs of the individual patient. These configurations offer devices that can taper from a larger diameter on top of the device and tapering down by as much as 18 mm at the bottom, or a smaller diameter on top and flaring by as much as 18 mm larger on the bottom.

Investigational and withdrawn devices — Several devices for thoracic endovascular repair are investigational and not commercially available in the United States. These include the LeMaitre TAArget (formerly Endofit), the JOTEC E-Vita stent-graft system, and the Streamliner Multilayer Flow Modulator (SMFM) device from Cardiatis. The investigations described below have been performed in Europe, and the devices listed have not been trialed or approved for use in United States. These grafts are briefly reviewed below.

Withdrawn devices include the original Talent thoracic stent, which was replaced by the later-generation Valiant stent-graft. The Navion graft, which was meant to be a next-generation Valiant device, was also discontinued.

TAArget — The TAArget (formerly called EndoFit) thoracic stent-graft consists of a nitinol skeleton of Z-shaped stents between two thin sheets of ePTFE. The proximal graft is available with and without a bare stent, and the device can be straight or tapered, allowing four different configurations that can be used alone or in combination.

The TAArget graft is available in diameters that range from 34 to 42 mm with lengths up to 20 cm. The device is deployed through a 22- or 24-French (7.33, 8 mm) sheath depending upon the diameter of the device.

In a study of 41 patients, indications for treatment were thoracic aneurysm (n = 24), acute contained aortic rupture (n = 5), aortic dissection (n = 6), penetrating atherosclerotic ulcers (n = 4), posttraumatic pseudoaneurysm (n = 1), and postcoarctation repair aneurysm (n = 1) [40]. The technical success rate was 100 percent. Perioperative mortality was 7.3 percent. One patient suffered from spinal cord ischemia with ongoing symptoms of lower extremity weakness. Three postoperative endoleaks were recorded, and two type I endoleaks (one proximal and one distal) resolved spontaneously. A third patient with persistent type Ia endoleak required operative conversion at one year. Overall long-term mortality was 17 percent at two-year follow-up with aneurysm-related mortality of 11 percent.

A retrospective review of 46 patients with thoracic aortic aneurysm and 41 with thoracic aortic dissection evaluated the EndoFit graft [41]. Twenty percent of the cases were performed emergently, and technical success was achieved in all the patients. Perioperative mortality (30-day) was 9.2 percent. Perioperative morbidity included neurologic complications in 9.3 percent of patients, including five strokes (two fatal) and three cases of paraplegia. Five patients had immediate proximal type I endoleak; three were remedied with a proximal cuff, one was rescued with tri-lobe balloon, and one was left untreated. The mortality rate over an average follow-up of 15.2 months was 11.5 percent but was not felt to be related to the aneurysm or stent-graft. There were no conversions required during the follow-up period.

A registry to follow the acute and chronic treatment of type B aortic dissection using the TAArget graft has been established (DEDICATED registry) [42].

E-Vita — The E-Vita stent-graft system (JOTEC) is composed of a woven polyester graft with a nitinol spring support structure sutured to the interior surface without any form of continuous longitudinal support, making the graft very flexible [43,44].

The graft is available in 24- to 44-mm diameters in lengths of 13, 15, 17, and 23 cm. Multiple graft configurations are available and can be used in combination (straight, tapered, open stent).

A review of 126 patients (71 percent men; age 64 [19 to 86] years) evaluated the performance of E-Vita stent-graft in the treatment of type B dissection (n = 56), thoracic aortic aneurysm (n = 25), penetrating aortic ulcer (n = 17), blunt thoracic injury (n = 10), mobile atheroma (n = 1), suture aneurysms (n = 7), and revision of prior endograft (n = 22) [43]. The procedure was emergent in 50 percent of the patients, and the graft was successfully placed in 77 percent of patients. An average of 1.3 stents was implanted per patient with a mean covered aortic length of 20.4 cm. The overall perioperative mortality (30-day) was 12.3 percent (1.5 for elective and 22 percent for emergency procedures). Transient spinal cord dysfunction was observed in two cases. Stroke occurred in 2.8 percent.

Streamliner Multilayer Flow Modulator — The Streamliner Multilayer Flow Modulator (SMFM) device is a self-expanding stent composed of cobalt alloy wires that are interconnected in five layers [45]. The stent is designed to allow blood flow through the mesh to maintain patency of collateral vessels, while promoting controlled thrombosis of the aneurysm sac. This novel but controversial device may be an alternative to complex endovascular repair, such as branched or fenestrated repairs. The device was approved for use in Europe in 2010. Clinical experience with this device is limited to a handful of observational studies and case reports [46-48]. In a systematic review, the overall technical success for placing the device was 77 percent.

In STRATO, a nonrandomized trial, the safety and efficacy of the device was evaluated in 23 high-risk surgical patients with Crawford type II or III thoracoabdominal aortic aneurysm [49]. Stable aneurysm thrombosis was achieved for 15 of 20 patients at 12 months, 12 of 13 at 24 months, and 10 of 11 at 36 months. The rate of branch patency was 96 percent at 12 months (primary patency), 100 percent at 24 months, and 97 percent at 36 months. Nine patients had endoleaks requiring 11 reinterventions, including three surgical repairs to achieve resolution.

Withdrawn

Talent thoracic stent-graft system — The Talent Thoracic Stent-Graft System was withdrawn from the market by the manufacturer and replaced with a next-generation device. It was a two-component device made of a woven polyester graft with an external self-expanding support structure of M-shaped nitinol stents and a longitudinal support bar throughout its length. The proximal component was a straight stent-graft with an uncovered stent proximally that allowed placement across the left subclavian or carotid artery.

The safety and efficacy of the Talent Thoracic Stent-Graft System was evaluated in the VALOR I study, which was a multicenter study that compared endovascular repair (n = 195) with retrospective open surgical data obtained from three centers (n = 189) [50]. At one-year follow-up, all-cause mortality was 16.1 percent and aneurysm-related mortality was 3.1 percent. Late complications included conversion to open surgery (0.5 percent), target aneurysm rupture (0.5 percent), stent-graft migration >10 mm (3.9 percent), and endoleak (12.2 percent).

The INSTEAD trial randomly assigned 597 patients with stable aortic dissection (>2 weeks) to elective aortic stent-grafting plus medical therapy or medical therapy alone [51]. The Talent Thoracic Stent-Graft System was used in all cases. There was no significant difference in overall mortality between the groups at two years, with a cumulative survival rate of 95.6 percent for medical therapy alone compared with 88.9 percent for endovascular repair. Aortic remodeling with recovery of the true lumen and thrombosis of the false lumen was found in significantly more patients undergoing endovascular repair (91.3 versus 19.3 percent) compared with medical therapy alone. In spite of favorable aortic remodeling, no improvements were seen in two-year survival or adverse event rates.

Valiant Navion graft — The Valiant Navion graft was a next-generation device that was approved for use in the United States in 2018 and subsequently recalled voluntarily by the manufacturer in February of 2021 with instructions to clinicians to immediately cease use of the device in new patients. The recall was due to concerns over stent fracture and endoleak occurring in some patients. The Navion graft was a lower-profile evolution of the Valiant Captivia thoracic stent-graft system and also featured both CoveredSeal (proximal-covered) and FreeFlo (proximal bare metal) stent configurations, which provided surgeons with two graft options for treating a variety of patient anatomies and pathologies. The pivotal results for the Valiant Navion stent-graft system were reported from the Valiant Evo global clinical trial. Thoracic endovascular repair was performed in 87 consecutive patients with a descending thoracic aortic aneurysm. There were no access or deployment failures. Two secondary procedures (one retrograde type A dissection, one aortic arch rupture) were required, and in the first 30 days, two patients died, leading to a freedom from all-cause mortality of 97.7 percent. Endoleaks at one month were reported in 2.5 percent of patients (one type Ia, one type II). Ongoing follow-up reports are anticipated [52]. The device is no longer available, and further information resulting from the Navion graft recall may become available in the future.

COMPARATIVE STUDIES — There are no trials directly comparing the outcomes of specific endovascular stent-grafts to each other for the management of thoracic aortic pathology. It is unlikely that such studies will ever be performed.

Two studies have compared endovascular with open surgical repair of thoracic aortic aneurysm. These studies are discussed above, and the implications of these results for the treatment of thoracic aortic aneurysm are discussed elsewhere. (See 'TAG and CTAG' above and "Management of thoracic aortic aneurysm in adults".)

Other studies comparing endovascular repair with open repair for the treatment of aortic dissection and traumatic aortic transection are also presented above. (See 'Withdrawn' above and 'TAG and CTAG' above and 'Valiant' above.)

ADVANCED DEVICES — When aortic disease is more extensive and involves branch vessels, the complexity and risks associated with endovascular repair increase. Approaches to address these issues include debranching procedures and the use of fenestrated and branched endografts.

Debranching procedures involve the ligation and surgical revascularization (eg, carotid-subclavian bypass) of an aortic branch that will be covered by the endograft. The role of debranching in the treatment of thoracic aneurysm is discussed elsewhere. (See "Endovascular repair of the thoracic aorta".)

Fenestrated grafts — The use of fenestrated-endovascular aneurysm repair (FEVAR) to manage more challenging aortic anatomy continues to evolve [53-64]. The Zenith Fenestrated AAA Endovascular Graft is the only device approved device for use in the US and specifically for the treatment of pararenal abdominal aortic aneurysm (AAA). Other branched devices to treat thoracoabdominal aneurysms are under investigation. Enrollment was recently completed in the early feasibility study evaluating the Gore Excluder Thoracoabdominal Branch Endoprosthesis (TAMBE) for the treatment of aortic aneurysms involving the visceral branch vessels. The TAMBE is designed to be the first complete off-the-shelf solution for the treatment of this complex disease.

Branched grafts — Branched grafts have separate smaller side arm grafts 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. (See "Endovascular devices for abdominal aortic repair", section on 'Fenestrated grafts'.)

Branched grafts have been used in patients with thoracic or thoracoabdominal aneurysms, or thoracic dissection [65,66]. Initial experience with branched aortic grafts has shown similar perioperative mortality as conventional endovascular repair, but the rate of aneurysm repair-related morbidity may be higher.

●Aortic arch branch devices – Single- and double-branch thoracic aortic endografts and fenestrated endografts are available primarily for investigational use to treat zone 0 (innominate), 1 (left carotid) or 2 (left subclavian) (figure 6). These include the Cook a-Branch, Cook fenestrated, Gore Thoracic Branch Endoprosthesis (TBE), Medtronic Valiant Mona LSA, Bolton ascending thoracic device, and Nexus aortic arch system. These grafts are intended to preserve flow into the innominate, carotid, or subclavian artery during thoracic endograft placement. A separate access is needed to deploy the branch grafts. None of these devices are approved for use by the US Food and Drug Administration (FDA). Device clinical trials evaluating use in treating aortic arch pathology are anticipated.

●Visceral devices – Branched grafts to the visceral vessels allow endovascular repair of more extensive aortic disease [67,68]. The use of visceral branch devices is discussed elsewhere. (See "Endovascular repair of abdominal aortic aneurysm", section on 'Advanced devices and techniques'.)

●Iliac devices – Iliac branched grafts are intended to preserve flow into the internal iliac artery during abdominal aortic or iliac aneurysm repair that requires extension beyond the internal iliac artery orifice. 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 — No one device is appropriate for all clinical indications or has been shown to be superior to any other device for the endovascular repair of the thoracic aorta. Most devices were originally designed for excluding thoracic aortic aneurysm, and the evaluation of specific designs to manage acute aortic syndromes (aortic rupture, aortic dissection) is in early stages. With time, and with the addition of disease-specific endografts, a clear preference for one device over another may emerge.

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

●Thoracic endovascular repair – Endovascular aneurysm repair refers to the stepwise insertion of endovascular graft components, usually via a femoral approach. Endovascular repair of the thoracic aorta has become the first-line intervention for a variety of aortic pathologies (eg, aneurysm, dissection, rupture, ulcer, intramural hematoma) due to reduced morbidity and mortality compared with open surgical repair. Endovascular aortic repair requires that specific anatomic criteria be fulfilled, and, for those with appropriate anatomy, allows the treatment of patients who might not otherwise be candidates for aortic repair. (See 'Introduction' above.)

●Endovascular devices

•Basic components – Although there are significant variations in endovascular graft design, three types of components are common to all: a delivery system, main body device, and graft extensions. Upon deployment, the endograft expands, contacting the thoracic aortic wall proximally and distally excluding pathology associated with the aortic wall from aortic blood pressure and flow. (See 'Basic principles' above.)

•Selection – Although graft design has evolved, an ideal graft suited to all circumstances is not available. Available stent-graft devices include the TAG and CTAG, TX2 and Alpha, the Valiant, and Relay/RelayPro stent-grafts. Other devices remain investigational in the United States. There are no randomized trials comparing the outcomes of specific endovascular stent-grafts to each other for the management of thoracic aortic pathology. (See 'Thoracic devices' above and 'Comparative studies' above.)

•Advanced devices – The indications for endovascular treatment of thoracic aortic pathologies have expanded, and the cases being treated are increasingly complex. When aortic disease is more extensive and involves branch vessels, approaches include debranching procedures and the use of fenestrated or branched endografts. Advanced endovascular aortic devices are designed to allow perfusion into specific aortic branch arteries depending upon the level of repair (eg, carotid, subclavian, renal). (See 'Advanced devices' above.)

●Complications – The placement of aortic endovascular grafts is associated with device-related complications that can include component disconnect, stent-graft buckling, and migration over time. In the thoracic aorta, secondary intervention is needed in 10 to 60 percent of patients, more commonly in patients undergoing endovascular repair of thoracic dissection. As such, these devices require lifelong surveillance; long-term outcomes continue to be studied. (See "Endovascular repair of the thoracic aorta", section on 'Late complications and outcomes' and "Complications of endovascular abdominal aortic repair".)

ACKNOWLEDGMENT — The editorial staff at UpToDate acknowledges Ronald M Fairman, MD, who contributed to an earlier version of this topic review.