Endovascular Repair of Aortic Aneurysms

Number: 0651

Policy

Aetna considers endovascular repair of infra-renal abdominal aortic or aorto-iliac aneurysms with a Food and Drug Administration (FDA)-approved fenestrated, branched or nonfenestrated endovascular stent graft medically necessary.

Aetna considers endovascular repair of descending thoracic aortic aneurysms with a FDA-approved endoprosthesis medically necessary. 

Aetna considers computed tomography (CT) surveillance after endovascular (stent) aortic repair at 1 month, 6 months, and 12 months following repair, then every year  medically necessary.

Aetna considers the following experimental and investigational because their effectiveness has not been established:

• Bifurcated-bifurcated aneurysm repair of aorto-iliac aneurysms
• Endovascular aneurysm sealing system (Nellix device) for the treatment of abdominal aortic aneurysms (including failed endovascular aneurysm repairs)
• Fabric/mesh wrapping of abdominal aortic aneurysms
• Implanted wireless pressure sensors for detection of endoleaks in the aneurysmal sac following endovascular repair
• Pre-operative embolization of the inferior mesenteric artery to reduce the rate of type II endoleak following endovascular abdominal aortic aneurysm repair.

Background

Aortic aneurysms can develop anywhere along the length of the aorta, but 3/4 are located in the abdominal aorta.  Thoracic aortic aneurysms, including those that extend from the descending thoracic aorta into the upper abdomen (thoraco-abdominal aneurysms), account for 1/4 of aortic aneurysms.

Abdominal aortic aneurysms (AAAs) are the most common form of aortic aneurysm, and are a potentially life-threatening condition.  It is estimated 1 to 4 % of persons over age 50 years are affected (O'Connor, 2002).  Rupture of an AAA is the 13th most common cause of death in the United States.

Abdominal aortic aneurysm is usually the result of degeneration in the media of the arterial wall, resulting in a slow and continuous dilatation of the lumen of the vessel.  In fewer than 5 % of cases, AAA is caused by mycotic aneurysm of hematogenous origin.  Abdominal aortic aneurysms are usually asymptomatic until they expand or rupture.  Presence of a pulsatile abdominal mass is virtually diagnostic but is found in less than 50 % of cases.  Rupture is uncommon if aneurysms are less than 5 cm in diameter, but ruptures are dramatically more common for aneurysms greater than 6 cm in diameter.  Without prompt intervention, ruptured aneurysms are often fatal.  Thus, elective surgical repair is usually recommended for all aneurysms greater than 6 cm unless surgery is contraindicated (Beers et al, 1999).  In patients who are good surgical risks, elective repair is generally recommended for aneurysms between 5 and 6 cm (mortality, about 2 to 5 %).

For an AAA, the standard open approach to repair involves a long midline abdominal incision, and placement of a graft in the aneurismal sac.  It is now possible to secure a bifurcated graft within an aneurysm at the latter site using a femoral approach from within the vessel.  The use of an endovascular graft may be considered when the risks of an open repair of the aneurysm are unacceptable, and the risk of aneurysm rupture is high, as indicated by any of the following criteria:

1. diameter of aneurysm is greater than 5 cm; or
2. diameter of aneurysm is 4 to 5 cm and has increased in size by 0.5 cm in the past 6 months; or
3. diameter of aneurysm is twice the diameter of the normal infrarenal aorta.

Current endovascular graft stents require an infra-renal non-aneurysmal neck length of at least 15 mm; however, there are case reports that describe the use of a fenestrated stent graft (Zenith, Cook, Inc., Bloomington, IN) customized to meet the anatomic needs of the individual patient.  The Zenith fenestrated graft, which is not FDA-approved, is based on Cook's FDA-approved Zenith AAA endovascular graft design.  It incorporates scallops at the top and openings in the graft wall called fenestrations that allow it to be implanted precisely in the aorta across adjacent blood vessels without blocking blood flow through those vessels.  Accurate placement of a fenestration over the orifice of a target vessel is feasible, but long-term maintenance of position is dependent on secure graft fixation (Stanley, 2001).

Verhoeven et al (2004) used a customized fenestrated graft based on the Cook Zenith composite system on 18 patients who had the following criteria: abdominal aneurysm at least 55 mm in diameter, a short neck (less than 15 mm), and contra-indications for open repair (cardiopulmonary impairment or a hostile abdomen).  Additional stents were used to ensure apposition of the fenestrations with the side branches.  Of the 46 targeted side branches, 45 were patent at the end of the procedure.  At follow-up (mean of  9.4 months), all of the remaining targeted vessels stayed patent.  The authors concluded that by customizing fenestrated stent-grafts, it is possible to position the first covered stent completely inside the proximal neck, thus achieving a more stable position.  This technique may become a valuable alternative for patients with a short infrarenal non-aneurysmal neck length; however, more patients with longer follow-up are required to determine the long-term safety and effectiveness of the device.

Verhoeven and colleagues (2009) noted that recent developments with fenestrated and branched stent grafts have opened the way to treat complex aortic aneurysms involving the visceral arteries.  Early reports on endovascular treatment of thoraco-abdominal aneurysms have demonstrated the feasibility of the technique.  Given the sparse literature, its safety has not been established yet.  These researchers performed a literature review and also presented the results of their own series of 30 patients treated with a custom-made Zenith device with fixed branches are presented.  Most of the patients were refused open surgery mainly for the extent of the disease combined with co-morbidity, which included in most patients a combination of several risk factors.  The mean aneurysm size was 70 mm and the extent of the aneurysm was type I in 8 cases, type II in 5, type III in 12 and type IV in 5 patients.  Technical success in the authors' series was achieved in 93 % (28/30).  Two out of 97 (2 %) targeted vessels were lost.  In 1 patient, a renal artery ruptured during insertion of the bridging stent graft.  In a second patient, a celiac artery could not be catheterized and was lost.  The 30-day mortality was 6.7 % and corroborated with 5.5 % in the largest series reported so far.  The 6-month and 1-year survival were 89.3 % and 76.0 %, respectively.  The authors concluded that the results of fully endovascular repair of selected thoraco-abdominal aneurysms are promising.  A learning curve should be expected.  Anatomical limitations such as extremely tortuous vessels and access problems should be taken into account, as well as the quality of the targeted side branches.  Although longer-term results need to be awaited, it is likely that endovascular repair of thoraco-abdominal aneurysms will become a preferential treatment option for many patients in the future.

The Zenith Alpha thoracic endovascular graft was approved by the FDA on September 15, 2015.  It is  indicated for the endovascular treatment of patients with isolated lesions of the descending thoracic aorta (not including dissections) having vascular anatomy suitable for endovascular repair, including:

• Iliac/femoral anatomy that is suitable for access with the required introduction systems; and
• Non-aneurysmal aortic segments (fixation sites) proximal and distal to the thoracic lesion:
  
  
  • with a length of at least 20 mm, and
  • with a diameter measured outer wall to outer wall of no greater than 42 mm and no less than 15 mm

Monahan and Schneider (2009) stated that open surgical repair of complex aortic aneurysms, such as juxtarenal or thoraco-abdominal aortic aneurysms, is a highly demanding procedure.  They frequently require major surgical exposure through both the thoracic and the abdominal cavities, supra-renal or supra-celiac aortic cross-clamping, and exposure of the visceral and renal arteries.  Endovascular aortic repair and thoracic endovascular aortic repair have become the mainstay of treatment for infra-renal AAAs and descending thoracic aneurysms.  However, the obvious need to maintain perfusion of the visceral and renal arteries has limited application of endovascular techniques to treatment of more complex aneurysms.  Fenestrated and branched stent grafts are being developed to address this need and enable repair of complex aneurysms involving branch vessels exclusively using minimally invasive techniques.  Although these devices remain investigational in the United States, they have recently become commercially available in other countries and play an increasing role in the management of complex aortic aneurysms.

Amiot and associates (2010) evaluated the medium-term outcomes following aortic aneurysm repair using fenestrated endografts performed in 16 French academic centers.  A retrospective analysis of prospectively collected data was carried out.  This study included all patients treated with fenestrated endografts in France between May 2004 and January 2009.  Patients were judged to be at high-risk for open surgical repair.  Fenestrated endografts were designed using computed tomography (CT) reconstructions performed on 3-dimensional work-stations.  All patients were evaluated with CT, duplex ultrasound and plain film radiograph at discharge, 6, 12, 18 and 24 months, and annually thereafter.  A total of 134 patients (129 males) were treated over the study period.  Median age and aneurysm size were 73 years (range of 48 to 91 years) and 56 mm (range of 45 to 91 mm), respectively.  A total of 403 visceral vessels were perfused through a fabric fenestration, including 265 renal arteries.  One early conversion to open surgery was required.  Completion angiography and discharge CT scan showed that 398/403 (99 %) and 389/394 (99 %) respective target vessels were patent.  The 30-day mortality rate was 2 % (3/134).  Pre-discharge imaging identified 16 (12 %) endoleaks: 3 type I, 12 type II and 1 type III. After the procedure, transient or permanent dialysis was required in 4 (3 %) and 2 (1%) patients, respectively.  The median duration of follow-up was 15 months (range of 2 to 53 months).  No aneurysms ruptured or required open conversion during the follow-up period.  Twelve of 131 patients (9 %) died during follow-up (actuarial survival at 12 and 24 months: 93 % and 86 %, respectively).  Median time from procedure to death was 15 months.  None of these deaths were aneurysm related.  Aneurysm sac size decreased by more than 5 mm in 52 %, 65.6 % and 75 % of patients at 1, 2 and 3 years, respectively.  Three (4 %) patients had sac enlargement within the first year, associated with a persistent endoleak.  During follow-up, 4 renal artery occlusions were detected.  A total of 12 procedure-related re-interventions were performed in 12 patients during follow-up, including 6 to correct endoleaks, and 5 to correct threatened visceral vessels.  The authors concluded that the use of endovascular prostheses with graft material incorporating the visceral arteries is safe and effective in preventing rupture in the medium-term.  A predictable high mortality rate was depicted during follow-up in this high-risk cohort.  Meticulous follow-up to assess sac behaviour and visceral ostia is critical to ensure optimal results.

An evidence report from the Agency for Healthcare Research and Quality (Wilt et al, 2006) on treatment options to repair AAA found that more research is needed to evaluate the long-term benefits and harms of endovascular repair versus open surgical repair.  According to this report, in patients medically fit for surgery and with an AAA of 5.5 cm or more, endovascular repair is a less invasive procedure, requires a shorter length of stay, and is associated with lower 30-day morbidity and mortality that open surgical repair.  However, studies have not shown improved quality of life beyond 3 months or survival beyond 2 years, according to the report.  Endovascular repair is associated with more complications, increase need for re-intervention, more long-term radiological monitoring, and greater costs when compared with open surgical repair.  A 4-year study of 166 endovascular repair patients medically unfit for surgery found that endovascular repair did not confer any survival benefit compared with no intervention.  The authors concluded that research is needed to evaluate the cost-effectiveness of endovascular repair in the United States (Wilt et al, 2006).  Research is also needed to evaluate whether the outcomes of endovascular repair procedures are influenced by either hospital volume or the surgeon's experience.

Lee and Faries (2007) noted that the increasing use of endografts to treat AAA has prompted the need for improved post-operative imaging and surveillance.  Although patients benefit from decreased morbidity with endovascular repair compared with open AAA repair, the long-term outcome of stent repair has yet to be fully determined.

Jonk et al (2007) performed a systematic review of the cost-effectiveness of AAA repair.  Of the 20 eligible articles, there were 3 randomized controlled trials (RCTs), 12 case series, 4 Markov models, and 1 systematic review.  Regardless of time frame, all studies found that endovascular repair costs more than open surgery.  Although the high cost of the endovascular prosthesis was partially offset by reduced intensive care, hospital length of stay, operating time, blood transfusions, and peri-operative complications, hospital costs were still greater for endovascular than open surgical repair.  For patients medically fit for open surgery, mid-term costs were greater for endovascular repair with no difference in overall survival or quality of life.  For patients medically unfit for open surgery, endovascular repair costs more than no intervention with no difference in survival.  The authors stated that although conclusions regarding the cost-effectiveness of AAA treatment options are time dependent and vary by institutional perspective, from a societal perspective, endovascular repair is not currently cost-effective for patients with large AAA regardless of medical fitness.

On the other hand, Brewster and colleagues (2006) reviewed a 12-year experience with endovascular AAA repair (EVAR) to document late outcomes.  During the interval between January 7, 1994 and December 31, 2005, a total of 873 patients underwent EVAR utilizing 10 different stent graft devices.  Primary outcomes examined included operative mortality, aneurysm rupture, aneurysm-related mortality, open surgical conversion, and late survival rates.  The incidence of endoleak, migration, aneurysm enlargement, and graft patency was also determined.  Finally, the need for re-intervention and success of such secondary procedures were evaluated.  Kaplan-Meier and multi-variate methodology were used for analysis.  Mean patient age was 75.7 years (range of 49 to 99 years); 81.4 % were male.  Mean follow-up was 27 months; 39.3 % of patients had 2 or more major co-morbidities, and 19.5 % would be categorized as unfit for open repair.  On an intent-to-treat basis, device deployment was successful in 99.3 %.  Thirty-day mortality was 1.8 %.  By Kaplan-Meier analysis, freedom from AAA rupture was 97.6 % at 5 years and 94 % at 9 years.  Significant risk factors for late AAA rupture included female gender (odds ratio OR, 6.9; p = 0.004) and device-related endoleak (OR, 16.06; p = 0.009).  Aneurysm-related death was avoided in 96.1 % of patients, with the need for any re-intervention (OR, 5.7; p = 0.006), family history of aneurysmal disease (OR, 9.5; p = 0.075), and renal insufficiency (OR, 7.1; p = 0.003) among its most important predictors.  A total of 87 (10 %) patients required re-intervention, with 92 % of such procedures being catheter-based and a success rate of 84 %.  Significant predictors of re-intervention included use of first-generation devices (OR, 1.2; p < 0.01) and late onset endoleak (OR, 64; p < 0.001).  Current generation stent grafts correlated with significantly improved outcomes.  Cumulative freedom from conversion to open repair was 93.3 % at 5 through 9 years, with the need for prior re-intervention (OR, 16.7; p = 0.001) its most important predictor.  Cumulative survival was 52 % at 5 years.  The authors concluded that EVAR using contemporary devices is a safe, effective, and durable method to prevent AAA rupture and aneurysm-related death.  Assuming suitable AAA anatomy, these data justify a broad application of EVAR across a wide spectrum of patients.

Frank et al (2007) performed a systematic review and meta-analysis of 12 years of EVAR.  A total of 163 studies pertaining to 28,862 patients undergoing EVAR were identified as relevant for the review and meta-analysis.  The pooled estimate for operative mortality was 3.3 % (95 % confidence interval [CI]: 2.9 to 3.6 %).  The pooled estimate for type 1 endoleaks was 10.5 % (95 % CI: 9.0 to 12.1 %), with an annual rate of 8.4 % (95 % CI: 5.7 to 12.2 %).  The pooled estimate of type 2,3 and 4 endoleaks was 13.7 % (95 % CI: 12.3 to 15.3 %), with an annual rate of 10.2 % (95 % CI: 7.4 to 14.1 %).  The pooled estimate for primary conversion to open repair was 3.8 % (95 % CI: 3.2 to 4.4 %), and for secondary conversion to open repair 3.4 % (95 % CI: 2.8 to 4.2 %).  The pooled estimate for post-operative rupture was 1.3 % (95 % CI: 1.1 to 1.7 %), with an annual rupture rate of 0.6 % (95 % CI: 0.5 to 0.8 %).  Multi-variate meta-regression analysis showed that rates of operative mortality, post-operative rupture and total number of endoleaks all fell significantly (p < 0.05) over time.  The authors concluded that this study demonstrated a low mortality and a gradual reduction in vascular morbidity and mortality associated with EVAR since it was first introduced.

In a systematic review, Lederle et al (2007) compared the effectiveness of treatment options, including active surveillance, open repair, and endovascular repair, for unruptured AAAs.  Randomized trials that compared open or endovascular AAA repair with another treatment strategy and published clinical outcomes were included.  Two trials compared open repair with surveillance for small AAAs (n = 2,226).  Repair did not improve all-cause mortality (relative risk, 1.01 [95 % CI: 0.77 to 1.32]) or AAA-related mortality (relative risk, 0.78 [CI: 0.56 to 1.10]).  Four trials compared open repair with endovascular repair (n = 1,532).  Endovascular repair reduced 30-day mortality (relative risk, 0.33 [CI: 0.17 to 0.64]) but not mid-term (up to 4 years) mortality (relative risk, 0.95 [CI: 0.76 to 1.19]).  One trial compared endovascular repair with observation in 338 patients who were unfit for open repair.  Endovascular repair did not reduce all-cause mortality or AAA-related mortality, but high cross-over and procedural mortality rates complicate interpretation of results.  The authors concluded that repairing AAAs smaller than 5.5 cm has not been shown to improve survival.  Endovascular repair is associated with lower operative mortality than open repair, similar mid-term mortality, and unknown long-term mortality and has not been shown to improve survival in patients unfit for open repair.  They stated that long-term trial data comparing endovascular repair with open repair are needed, as is another trial comparing endovascular repair with observation in high-risk patients.

Thoracic aortic aneurysms (TAAs) may be idiopathic and have been associated with congenital connective tissue disorders (e.g., Ehlers-Danlos syndrome, Marfan's syndrome).  Tertiary syphilis is an uncommon cause of aneurysms.  Thoracic aneurysms may become huge while remaining asymptomatic.  Symptoms relate to pressure against or erosion of adjacent structures by the enlarging aorta, such as pain, cough, wheezing, hemoptysis, dysphagia, or hoarseness.  Thoracic aneurysms generally should be resected if greater than or equal to 6 cm (Beers et al, 1999).  However, aneurysms in patients with Marfan's syndrome are prone to rupture, so elective surgical repair is recommended for aneurysms 5 to 6 cm.  Surgical repair consists of resection of the aneurysm and replacement with a synthetic conduit.  Some surgeons use a homograft of the proximal aorta and aortic valve instead of synthetic materials.

Following diagnosis, untreated patients with TAAs have a 2-year survival rate of less than 30 %, with 50 % of all deaths caused by aneurysm rupture.  Complications of conventional repair include post-operative paraplegia (25 %), renal failure (20 %), bleeding, stroke, and prolonged ventilator dependence.  In addition, the operative mortality of the open procedure has been reported to be about 10 %.

Endovascular repair of TAAs is one of the most recent technological advancements in vascular surgery.  The current technique and available technology allow the repair of TAAs distal to the left subclavian artery (Najibi et al, 2002).  This less-invasive approach has the potential to reduce the morbidity and mortality associated with the traditional open operative repair of TAAs.  In addition, high-risk patients who would not be considered for open repair and would not be treated may now be candidates for this minimally invasive procedure.

The GORE TAG Thoracic Endoprosthesis System (W.L. Gore and Associates, Inc., Flagstaff, AZ) received pre-market approval (PMA) from the FDA for endovascular repair of descending TAAs in patients with the following criteria:

1. adequate iliac/femoral access;
2. aortic inner diameter in the range of 23 mm to 27 mm; and
3. less than or equal to 2 cm non-aneurysmal aorta proximal and distal to the aneurysm. 

The graft is made of expanded polytetrafluoroethylene (ePTFE) with an outer self-expanding nitinol support structure and is inserted into the diseased area of the aorta through a catheter inserted in the groin.

Gore's non-randomized pivotal study compared TAG (n = 140) with open surgery (n = 94) in 17 U.S. sites.  The control group included patients who already had undergone open-surgical repair of aneurysms in the thoracic aorta (n = 50) as well as concurrent patients (n = 44), some of whose aneurysm neck length made them unsuitable for the device cohort, and some of whom were TAG-eligible.  Gore conducted a confirmatory study (n = 51) after the graft was re-designed to avoid fracture.  Study results reported the TAG group was associated with reduced aneurysm-related deaths compared to the surgical group.  The proportion of subjects who experienced at least 1 major adverse event (e.g., bleeding, hematoma, renal failure) through 1 year post-treatment was 42 % for the TAG group versus 77 % for the control.  One major adverse event was reported between months 12 and 24.  In the confirmatory study, the proportion of subjects who experienced at least 1 major adverse event was 12 % of the 51 TAG patients versus 70 % of the control.  No deaths were reported for the TAG group during the first 30 days compared with 6 % of the surgical control.  In addition, Gore reported that the median stay in intensive care was 1 day for the TAG group versus 3 for the control group and median length of hospital stay was 3 days for TAG versus 10 for surgery patients.  The TAG group also experienced less median blood loss and returned to normal daily activities sooner.

The Interventional Procedures Advisory Committee of the National Institute for Clinical Excellence (NICE, 2005) is examined endovascular stent-graft placement in TAAs.  Provisional recommendations from the Committee state that it is a suitable alternative to surgery in properly selected patients; however, the Committee emphasizes that these recommendations are provisional and subject to change. 

A systematic review of the published evidence on this procedure that was commissioned by NICE (2004) identified a total of 29 studies of endovascular stent-grafting for TAAs: 27 case series and 2 comparative observational studies.  In 1 comparative study, the technical success rate was 100 % (67/67 patients).  The systematic review reported that the overall technical success rate was 93 % over 18 studies (16 case series and 2 comparative studies).

The systematic review reported that the rate of conversion to open repair varied from 0 % (0/26 patients) to 7 % (1/14 patients).  The proportion of patients who experienced an increase in aneurysm size varied from 0 % (0/18) to 7 % (2/29) of patients.  In the study with the largest number of patients, the aneurysm increased in size (by = 5 mm) in 5 % (4/84) of patients.  The proportion of patients who experienced a decrease in aneurysm size varied from 100 % of patients (18/18) to 17 % (5/29) of patients.  The 30-day mortality rate varied from 0 % (in several studies with a combined population of 94 patients) to 14 % (2/14) of patients.  The overall mortality ranged from 3 % (1/37 patients) to 24 % (11/46 patients) across 17 studies over a mean follow-up of 14 months.

The most commonly reported complication following TAA stent-graft placement was endoleak (incomplete sealing of the aneurysm).  Nineteen studies reported at least 1 patient with an endoleak, with a mean incidence of 13 % over 12 months (the total number of patients in these studies was 752; follow-up ranged from 3 to 25 months).  Five studies with a total of 83 patients reported that there were no cases of endoleak during a mean follow-up period of 12 months.  Injuries to the access artery were reported in 9 case series, and included iliac artery dissection in 4 % (1/26 patients), perforation of the iliac artery in 4 % (1/27 patients) and dissection/rupture of the femoral artery in 6 % (2/34 patients).  One case series reported stent fracture in 13 % (11/84) of patients, and 6 cases of stent migration were reported over 15 case series.  Other reported complications included wound complications in 25 % (8/32) of patients, stroke in 19 % (8/43), renal failure requiring dialysis in 11 % (2/19), and paraplegia in 7 % (3/43) of patients.  The NICE Interventional Procedure Advisory Committee noted that there is a lack of long-term data on the durability of TAA stent-grafts.

Gore is conducting a post-approval study to evaluate all-cause mortality, aneurysm-related mortality, morbidity and device-related adverse events at 30 days and 1 year post-procedure.  Another condition of approval is the completion of a 2-day training program as a prerequisite for ordering TAG.

Other endoprosthesis for TAAs under clinical investigation in the United States include the Talent (Medtronic Inc., Sunrise, FL), Valiant with the Xcelerant delivery system (Medtronic Inc., Sunrise, FL), and Zenith TX2 (Cook, Inc., Bloomington, IN).

Surgically repaired abdominal aortic aneurysms have a risk of rupture due to leakage around the graft.  Patients are periodically monitored with contrast enhanced computed tomography (CT) after stent graft placement for endoleak and sac dilation which indicate increased risk of rupture.

In order to reduce the risks of rupture, endosensors are being developed to monitor abdominal aortic aneurysm pressure after endovascular repair.  One manufacturer is developing a wireless radiofrequency endosensor (e.g., CardioMEMS Endosensor, CardioMEMS, Inc., Atlanta, GA).  Once implanted into the aneurysm, the endosensor measures the pressure inside the sac.  The pressure measurements transmitted via radiofrequency to a device held over the patient's body, where pressure readings are recorded.  The device may reduce the necessary frequency of periodic monitoring of the aneurysmal sac with contrast-enhanced CT.  Clinical studies of the CardioMENS Endosensor are currently ongoing.

Another endosensor, the Impressure AAA Sac Pressure Transducer, is being developed by Remon Medical,and consists of a piezoelectric membrane, which when actuated by ultrasound waves from a hand-held probe charges a capacitor.  Once charged, the transducer measures ambient pressure, then generates an ultrasound signal, which is relayed to the probe.  The data can then be down-loaded and exported as an Excel data file consisting of pressure measurements and the corresponding times at which the measurements were taken.

Ellozy et al (2004) reported on the first clinical experience with the use of the Impressure permanently implantable, ultrasound-activated remote pressure transducer to measure intra-sac pressure after endovascular repair of abdominal aortic aneurysms.  Over 7 months, 14 patients underwent endovascular repair of an infra-renal AAA with implantation of the remote pressure transducer fixed to the outside of the stent graft and exposed to the excluded aortic sac.  Twelve patients received modular bifurcated stent grafts, and 2 patients received aorto-uniiliac devices.  Intra-sac pressures were measured directly with an intravascular catheter and by the remote sensor at stent-graft deployment.  Follow-up sac pressures were measured with a remote sensor and correlated with systemic arterial pressure at each follow-up visit.  Mean follow-up was 2.6 +/-1.9 months.  The investigators reported "excellent" concordance between catheter-derived and transducer-derived intra-sac pressssure intra-operatively, with a Pearson correlation coefficient for systolic, diastolic, and pulse pressures of 0.97, 0.97, and 0.96, respectively (p < 0.001).  Pulsatile waveforms were seen in all functioning transducers at each evaluation interval.  One implant ceased to function at 2 months of follow-up.  In 1 patient a type I endoleak was diagnosed on 1-month CT scans; 3 type II endoleaks were observed.  The investigators reported that those patients with complete exclusion of the aneurysm on CT scans had a significant difference in systemic and sac systolic pressures initially (p < 0.001) and at 1 month (p < 0.001).  Initial sac diastolic pressures were higher than systemic diastolic pressures (p < 0.001).  The investigators reported that the ratio of systemic to sac systolic pressure increased over time in those patients with complete aneurysm exclusion (p < 0.001).  Four of 6 patients with no endoleak and greater than 1-month follow-up had diminution of sac systolic pressure to 40 mm Hg or less by 3 months.  The investigators concluded that additional clinical follow-up will be necessary to determine whether aneurysm sac pressure monitoring can replace CT in the long-term surveillance of patients after endovascular repair of aortic aneurysms.

Ohki et al (2007) stated that complete exclusion and de-pressurization of the aneurysm sac is the prime goal of EVAR of AAAs.  Thus, any EVAR that results in a type I or III endoleak has been classified as a technical failure.  The current method to detect endoleaks uses intra-operative aortography.  However, aortography is limited by its subjective nature, inability to quantify the significance of the endoleak, and artifacts such as bowel gas that may mimic an endoleak.  In addition, repetitive contrast injection may impair renal function.  To increase the safety and effectiveness of intra-operative endoleak detection, a wireless pressure-monitoring system has been developed and tested in the clinical setting.  The APEX trial (Acute Pressure Measurement to Confirm Aneurysm Sac EXclusion) is a prospective, multi-center/international trial sponsored by CardioMEMS to evaluate the safety and effectiveness of the EndoSure wireless pressure sensor for EVAR.  The 30 x 5 x 1.5-mm sensor contains no battery and is powered externally with radiofrequency energy.  The sensors are extremely stable, operate over the full physiological range of pressures, and have a resolution of 1 mm Hg.  A total of 90 patients were enrolled at 12 sites, 76 of whom were eligible for analysis.  The sensor was implanted via the contralateral femoral artery at the time of EVAR.  The sac pulse pressure was measured with both an angiographical catheter and the sensor after deployment of the main endograft but before the deployment of the contralateral limb (type I endoleak equivalent).  Sac pressure was again measured with the sensor after deployment of the contralateral limb and completion of the EVAR.  Data were collected in a prospective manner.  In all of the eligible patients (n = 76), the initial sensor pressure measurement agreed closely with the angiographical catheter pressure measurement of the type I endoleak equivalent.  At the completion of the procedure, there was agreement between the sensor measurement and angiography regarding the presence or absence of a type I or III endoleak in 92.1 % (n = 70) of the measurements.  Overall, the sensitivity was 0.94 and the specificity was 0.80 for detecting type I or III endoleaks.  Final pulse pressures decreased significantly compared with baseline measurements.  The authors concluded that implantation of the wireless pressure sensor is safe, and remote aneurysm sac pressure sensing is feasible.  It was a valuable guide in evaluating the completeness of the EVAR procedure.  Moreover, they stated that long-term study will be needed to prove its effectiveness for post-operative surveillance.

Fabric wrapping for abdominal aortic aneurysms entails wrapping aneurysms with cellophane or fascia lata.  Karkos et al (2002) stated that "whether external wrapping does alter the outcome in patients with unresected AAAs and a gain in longevity for the individual can be achieved is unclear …. the question whether one could justify employing this old-fashioned technique, as a last resort, to delay rupture in selected poor-risk patients unfit for open repair, with large aneurysms that extend above the renal arteries and those unsuitable for endovascular surgery remains unanswered".

Fabric wrapping for abdominal aortic aneurysms has not been demonstrated to prevent eventual rupture.  In extremely rare instances, external wall reinforcement may be indicated when the current accepted treatment (excision of the aneurysm and reconstruction with synthetic materials) is not a viable alternative, but external wall reinforcement is not fabric wrapping.  It should also be noted that of fabric wrapping of abdominal aortic aneurysms is not covered by Medicare (2001).

Guidance from the National Institute for Health and Clinical Excellence (NICE, 2009) concluded that endovascular aortic stent-grafts are not recommended for patients with ruptured aneurysms except in the context of research.

Foster et al (2010) examined whether a policy for endovascular repair as the primary mode of treatment for ruptured abdominal aortic aneurysms (rAAAs) would improve outcomes.  A total of 1,328 papers were found; of these, 24 presented represent the best evidence to answer the clinical question.  The author, journal, date and country of publication, patient group studies, study type, relevant outcomes, results, and study weaknesses of these papers were tabulated.  The majority of data available derives from level 2b evidence, with only 1 single level 1b and no level 1a studies available.  Appraisal of theses studies was constrained by limited patient numbers, selection bias and heterogeneity in treatment protocols between the reported series.  The sole prospective, RCT comparing open and endovascular treatments found a 53 % mortality among patients treated by either modality.  This study was, however, under-powered and contrary to numerous cohort series that show reduced mortality with EVAR.  The largest body of evidence was found in a co-operative multi-center cohort study spanning 49 institutions that showed superiority of EVAR over open repair in terms of 30-day mortality.  The authors concluded that, within the limitations of the published literature to date, endovascular repair as the primary treatment for rAAA is achievable and appears to be associated with favorable mortality over open repair with appropriate case selection.

On the other hand, other published studies indicated that EVAR is not an established proceudre in treating ruptured aneurysms.  Vetrhus and associates (2009) noted that repair of AAAs is performed in more than 800 patients annually in Norway.  Open repair is an established procedure, but an increasing number of patients have undergone endovascular repair during the last decades.  This paper deliverd an updated discussion of infra-renal AAA repair.  A systematic search was performed in PubMed and literature containing the search terms "abdominal aortic aneurysm" and "mortality" (from 2004 to 2009) was retrieved.  The review was based on randomized, multi-center and registry studies examining complications and mortality in endovascular and open repair.  Peri-operative mortality is lower in endovascular repair.  The initial survival benefit is not sustained over time.  The mortality rate is still high in ruptured AAAs, but endovascular repair may improve mortality in selected patients.  The authors concluded that even though peri-operative mortality associated with endovascular repair is lower than that of open repair, questions concerning benefit and selection of patients are still left unanswered.

Palombo et al (2009) stated that evidence to support EVAR as first approach for patients with rAAA is drawn from 3 sources:

1. single-center series,
2. systematic reviews, and
3. population-based studies.

In order to validate EVAR, this technique was compared to the conventional open repair.  These studies were heterogeneous, and often failed to demonstrate any significant difference between EVAR and open repair.  More recently, some population-based studies from the United States suggested that there are advantages of EVAR over open repair with regard to 30-day mortality and morbidity.  Some bias have influenced the reported results including criteria for choice of EVAR varied across the studies according to the policy of the authors.  Therefore, any meta-analysis should be interpreted with caution.  Patients' conditions have directed the authors towards a technique instead of the other, namely, pathophysiological factors of the patients, and anatomical conditions of the AAAs.  The authors concluded that according to the current literature, the role of EVAR in the management of rAAAs must be further checked; RCTs could provide the evidence to define adequate indication to EVAR.

Karkos et al (2009) documented mortality after endovascular repair of rAAAs.  Articles that reported data on mortality after endovascular repair of rAAAs were identified.  Only patients with true ruptures were included.  Additionally, information on mortality after concurrent open repair was sought.  One of the authors reviewed all of the studies and extracted appropriate data.  A total of 43 articles were identified, 14 of which were excluded.  A total of 29 articles with 897 patients who underwent endovascular repair met the inclusion criteria.  Of the patients with available information, 86 % were men; 29 % had been operated on under local anesthesia; 28 % were hemodynamically unstable; 17 % required intra-aortic balloon occlusion; 48 % received bifurcated stent grafts; 6 % had endovascular procedures converted to open repair intra-operatively; and 5.5 % developed abdominal compartment syndrome.  In-hospital and/or 30-day mortality ranged between 0 % and 54 % in different series, whereas the pooled mortality after endovascular repair was 24.5 % (95 % CI: 19.8 % to 29.4 %).  In 19 studies reporting results of both endovascular and concurrent open repair from the same unit, the pooled mortality after open repair was 44.4 % (95 % CI: 40.0 % to 48.8 %), and the pooled overall mortality for rAAA undergoing endovascular or open repair was 35 % (95 % CI: 30 % to 41 %).  The authors concluded that endovascular repair of rAAAs is associated with acceptable mortality rates.  They stated that additional studies are needed to verify these promising results and precisely define the role of endovascular treatment as an additional therapeutic option for rAAAs.

Hinchliffe and colleagues (2009) performed a systematic literature review of EVAR of rAAA from 1994 to 2009.  The literature analyzed included systematic reviews and population-based studies of rAAA.  A total of 7 systematic reviews were identified, all demonstrating from published data that patients with EVAR of rAAA had significantly reduced mortality compared with controls.  Six recently published population-based studies from the United States demonstrated low mortality rates associated with EVAR; however, only a small proportion of rAAAs were treated by EVAR.  Systematic reviews and population-based studies both raised concerns about patient selection and publication bias.  Two RCTs are in progress, and 1 is due to commence 2009.  The authors concluded that the outcome of EVAR in a non-selected patient population remains unknown.  One or more definitive RCTs could provide the level I evidence to resolve these issues.

In a systematic review, Chambers et al (2009) examined the clinical effectiveness and cost-effectiveness of EVAR of AAAs in patients at varying levels of risk.  The following bibliographic databases were searched (2005 to February 2007): BIOSIS Previews, CINAHL, Cochrane Central Register of Controlled Trials, EMBASE, ISI Proceedings, MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, Science Citation Index and Zetoc Conferences.  A systematic review of the clinical effectiveness of EVAR was performed using standard methods.  Meta-analysis was employed to estimate a summary measure of treatment effect on relevant outcomes based on intention-to-treat analyses.  A second systematic review was undertaken to identify existing cost-effectiveness analyses of EVAR compared with open surgery and non-surgical interventions.  Two new decision models were developed to inform the review.  A total of 6 RCTs were included in the clinical effectiveness review; 34 studies evaluated the role of patients' baseline characteristics in predicting risks of particular outcomes after EVAR.  The majority were based on data relating to devices in current use from the EUROSTAR registry.  Compared with open repair, EVAR reduces operative mortality (OR 0.35, 95 % CI: 0.19 to 0.63) and medium-term aneurysm-related mortality (hazard ratio 0.49, 95 % CI: 0.29 to 0.83) but offers no significant difference in all-cause mortality.  Endovascular aneurysm repair is associated with increased rates of complications and re-interventions, which are not offset by any increase in health-related quality of life.  EVAR Trial 2 comparing EVAR with non-surgical management in patients unfit for open repair found no differences in mortality between groups; however, substantial numbers of patients randomized to non-surgical management crossed-over to receive surgical repair of their aneurysm.  The cost-effectiveness systematic review identified 6 published decision models.  Both models considered relevant for the decision in the United Kingdom concluded that EVAR was not cost-effective on average compared with open repair at a threshold of 20,000 pounds per quality-adjusted life-year (QALY).  Another model concluded that EVAR would be on average more cost-effective than no surgical intervention in unfit patients at this threshold.  The Medtronic model concluded that EVAR was more cost-effective than open repair for fit patients at this threshold.  The York economic evaluations found that EVAR is not cost-effective compared with open repair on average at a threshold of 30,000 pounds per QALY, with the results very sensitive to model assumptions and the baseline risk of operative mortality.  Exploratory analysis to evaluate management options in patients unsuitable for open surgery suggested that the cost-effectiveness of EVAR may be sensitive to aneurysm size and patient's age at operation.  Indicative modelling suggests that EVAR may be cost-effective for small aneurysms in some patient groups.  Ongoing RCTs will provide further evidence relating to these patients.  The authors concluded that open repair is more likely to be cost-effective than EVAR on average in patients considered fit for open surgery.  Endovascular aneurysm repair is likely to be more cost-effective than open repair for a subgroup of patients at higher risk of operative mortality.  These results are based on extrapolation of mid-term results of clinical trials.  Evidence does not currently support EVAR for the treatment of ruptured aneurysms.

Jonker et al (2010) stated that thoracic EVAR offers a less invasive approach for the treatment of ruptured descending thoracic aortic aneurysms (rDTAA).  Due to the low incidence of this life-threatening condition, little is known about the outcomes of endovascular repair of rDTAA and the factors that affect these outcomes.  These investigators retrospectively investigated the outcomes of 87 patients who underwent thoracic EVAR for rDTAA at 7 referral centers between 2002 and 2009.  The mean age was 69.8 +/- 12 years and 69.0 % of the patients were men.  Hypovolemic shock was present in 21.8 % of patients, and 40.2 % were hemodynamically unstable.  The 30-day mortality rate was 18.4 %, and hypovolemic shock (OR 4.75; 95 % CI: 1.37 to 16.5; p = 0.014) and hemothorax at admission (OR 6.65; 95 % CI: 1.64 to 27.1; p = 0.008) were associated with increased 30-day mortality after adjusting for age.  Stroke and paraplegia occurred each in 8.0 %, and endoleak was diagnosed in 18.4 % of patients within the first 30 days after thoracic EVAR.  Four additional patients died as a result of procedure-related complications during a median follow-up of 13 months; the estimated aneurysm-related mortality at 4 years was 25.4 %.  The authors concluded that endovascular repair of rDTAA is associated with encouraging results.  The endovascular approach was associated with considerable rates of neurological complications and procedure-related complications such as endoleak.  Further improvements of current endovascular devices are needed to reduce the endograft-related complications and deaths during follow-up.

In an editorial that accompanied the study by Jonker et al, Coselli and Gopaldas (2010) stated that "[a]lthough the current use of TEVAR for ruptured thoracic aneurysms remain off label, the success demonstrated by Jonker and colleagues and by several others establishes a strong foundation that would support the use of TEVAR as the primary modality for treating ruptured DTAA in the near future".

A scientific statement onSurgical management of descending thoracic aortic disease: Open and endovascular approachesfrom the American Heart Association (Coady et al, 2010) noted that "[t]reatment of acute aortic syndromes that affect the descending thoracic aorta continues to evolve with the development of new technologies and management strategies.  Although data presented in this summary have highlighted current outcomes of endovascular stenting compared with conventional open repair, it must be stressed that there have been no prospective randomized trials to compare these treatment strategies on a head-to-head basis.  In addition, although endovascular stenting offers a minimally invasive method of treatment, its long-term durability is still largely unknown.  Ongoing experience and national and international registries will continue to define precise roles for both surgical and endovascular therapy".

Huddle et al (2009) determined what laboratory values predict the prognosis of patients following EVAR.  MEDLINE and Cochrane Library databases were searched.  This resulted in 13 relevant articles.  Data were pooled, and meta-analyses were performed.  A meta-analysis including 5,655 patients showed that pre-operative serum creatinine greater than 1.5 mg/dL was a significant risk indicator for increased 30-day mortality (relative risk 3.0, 95 % CI: 2.3 to 4.1; p < 0.0001).  Four other studies showed that other cut-off values of creatinine or glomerular filtration rate (GFR) can predict mortality and complications following EVAR.  One study suggested that reduced pre-operative hemoglobin is a risk indicator for reduced long-term survival.  Increased serum creatinine, reduced GFR, and reduced hemoglobin are significant and strong predictors of mortality and complications after EVAR.  The authors concluded that current evidence remains limited, and further research is needed to determine conclusively additional laboratory values that may predict the outcome of patients following EVAR.

Linsen et al (2012) performed a systematic review of the current literature to analyze the immediate and follow-up results of fenestrated EVAR (FEVAR) in patients with para-renal AAAs.  The Medline, Embase, and Cochrane databases were searched to identify all studies reporting FEVAR of para-renal AAAs published between January 2000 and May 2011.  Two independent observers selected studies for inclusion, assessed the quality of the included studies, and performed the data extraction.  Studies were selected based on specific pre-defined criteria.  Outcomes were technical success (successfully completed procedure with endograft patency, preservation of target vessels, and no evidence of type I or III endoleak at post-procedural imaging), 30-day mortality, all-cause mortality, branch vessel patency, renal impairment, and secondary interventions.  Between-study heterogeneity was calculated using I(2) statistics.  Pooled estimates were calculated using a fixed-effects (I(2) < 25 %) or a random-effects (I(2) > 25 % to < 50 %) model.  A total of 9 studies were included reporting 629 patients who underwent FEVAR for a para-renal AAA, of which 1,622 target vessels were incorporated in an endograft design.  Between-study heterogeneity was less than or equal to 41% for all outcomes.  The pooled estimate (95 % CI: was 90.4 % (87.7 % to 92.5 %) for technical success, 2.1 % (1.2 % to 3.7 %) for 30-day mortality, and 16 % (12.5 % to 20.4 %) for all-cause mortality.  Follow-up was 15 to 25 months.  The pooled estimate (95 % CI) during follow-up was 93.2 % (90.4 % to 95.3 %) for branch vessel patency, 22.2 % (16 % to 30.1 %) for renal impairment, and 17.8 % (13.5 % to 22.6 %) for secondary interventions.  The authors concluded that promising immediate and mid-term results (up to 2 years) support FEVAR as a feasible, safe, and effective treatment in a relatively high-risk cohort of patients with pararenal AAAs.

Cross et al (2012) stated that FEVAR is a technically challenging operation.  The duration, blood loss, and risk of limb ischemia, contrast-induced nephropathy and re-perfusion injury are likely to be higher than after standard EVAR.  Benefits of FEVAR over open repair may be less than those seen with standard infrarenal EVAR.  These investigators performed a meta-analysis of observational studies of all published data for FEVAR, with the aim to high-light current issues around the evidence for the potential benefit of FEVAR.  A search was performed for studies describing FEVAR for juxta-renal AAAs.  Small series of fewer than 10 procedures and studies describing predominantly branched endografts or FEVAR for aortic dissection were excluded.  Authors of included papers were contacted to eliminate patient duplication.  A total of 11 studies were identified describing a total of 660 procedures.  Definitions of aneurysm morphology were variable, and clear inclusion and exclusion criteria were not always documented.  Double fenestrations were more common than triple or quadruple fenestrations.  Target vessel perfusion rates ranged from 90.5 to 100 %.  Eleven deaths occurred within 30 days, giving a 30-day proportional mortality rate of 2.0 %.  Morbidity was poorly reported.  The authors concluded that FEVAR for repair of supra-renal and juxta-renal aneurysms is a viable alternative to open repair.  However, there is no level 1 evidence for FEVAR, and current evidence is weak with many unanswered questions.

In a Cochrane review, Filardo and colleagues (2012) compared long-term survival in patients with AAAs of diameter 4.0 to 5.5 cm who received immediate repair versus routine ultrasound surveillance.  For this update the Cochrane Peripheral Vascular Diseases Group searched their Specialised Register (February 2012) and CENTRAL (2012, Issue 1).  Reference lists of relevant articles were checked for additional studies and the searches were supplemented by hand-searches of recent conference proceedings and information from experts in the field.  Randomized controlled trials in which men and women with asymptomatic AAAs of diameter 4.0 to 5.5 cm were randomly allocated to immediate repair or imaging-based surveillance at least every 6 months.  Outcomes had to include mortality or survival.  Two authors abstracted the data, which were cross-checked by the other authors.  Due to the small number of trials, formal tests of heterogeneity and sensitivity analyses were not conducted.  Four trials with a combined total of 3,314 patients, the UK Small Aneurysm Trial (UKSAT), the Aneurysm Detection and Management (ADAM) trial, the Comparison of Surveillance Versus Aortic Endografting for Small Aneurysm Repair (CAESAR), and the Positive Impact of Endovascular Options for treating Aneurysms Early (PIVOTAL) fulfilled the inclusion criteria.  The 4 trials showed an early survival benefit in the surveillance group (due to 30-day operative mortality with surgery) but no significant differences in long-term survival (adjusted hazard ratio (HR) 0.88, 95 % CI: 0.75 to 1.02, mean follow-up 10 years (UKSAT); HR 1.21, 95 % CI: 0.95 to 1.54, mean follow-up 4.9 years (ADAM); HR 0.76, 95 % CI: 0.30 to 1.93, median follow-up 32.4 months (CAESAR); HR 1.01, 95 % CI: 0.49 to 2.07, mean follow-up 20 months (PIVOTAL)).  The meta-analyses of mortality at 1 year (CAESAR and PIVOTAL only) and 6 years (UKSAT and ADAM only) revealed a non-significant association (Peto odds ratio at one year 1.15, 95 % CI: 0.59 to 2.25; Peto odds ratio at 6 years 1.11, 95 % CI: 0.91 to 1.34).  The authors concluded that these findings from the 4 trials to date demonstrated no advantage to early repair (via open or endovascular surgery) for small AAA (4.0 to 5.5 cm) and suggested that "best care" for these patients favors surveillance.  Furthermore, the more recent trials focused on the efficacy of EVAR and still failed to show benefit.  Thus, both open and endovascular repair of small AAAs are not supported by currently available evidence.

Brown and associates (2012) evaluated the effectiveness of EVAR against standard alternative management in patients with large AAA.  These researcehrs examined 2 national, multi-center randomized trials – EVAR trials 1 and 2.  Patients were recruited from 38 out of 41 eligible United Kingdom (UK) hospitals.  Men and women aged at least 60 years, with an AAA measuring at least 5.5 cm on a CT scan that was regarded as anatomically suitable for EVAR, were assessed for fitness for open repair.  Patients considered fit were randomized to EVAR or open repair in EVAR trial 1 and patients considered unfit were randomized to EVAR or no intervention in EVAR trial 2.  The primary outcome was mortality (operative, all-cause and AAA-related).  Patients were flagged at the UK Office for National Statistics with centrally coded death certificates assessed by an Endpoints Committee.  Power calculations based upon mortality indicated that 900 and 280 patients were required for EVAR trials 1 and 2, respectively.  Secondary outcomes were graft-related complications and re-interventions, adverse events, renal function, health-related quality of life and costs.  Cost-effectiveness analyses were performed for both trials.  Recruitment occurred between September 1, 1999 and August 31, 2004, with targets exceeded in both trials: 1,252 randomized into EVAR trial 1 (626 to EVAR) and 404 randomized into EVAR trial 2 (197 to EVAR).  Follow-up closed in December 2009 with very little loss to follow-up (1 %).  In EVAR trial 1, 30-day operative mortalities were 1.8 % and 4.3 % in the EVAR and open-repair groups, respectively: adjusted odds ratio 0.39 [95 % CI: 0.18 to 0.87], p = 0.02.  During a total of 6,904 person-years of follow-up, 524 deaths occurred (76 AAA-related).  Overall, there was no significant difference between the groups in terms of all-cause mortality: adjusted hazard ratio (HR) 1.03 (95 % CI: 0.86 to 1.23), p = 0.72.  The EVAR group did demonstrate an early advantage in terms of AAA-related mortality, which was sustained for the first few years, but lost by the end of the study, primarily due to fatal endograft ruptures: adjusted HR 0.92 (95 % CI: 0.57 to 1.49), p = 0.73.  The EVAR procedure was more expensive than open repair (mean difference of £1,177) and not found to be cost-effective, but the model was sensitive to alternative assumptions.  In EVAR trial 2, during a total of 1,413 person-years of follow-up, a total of 305 deaths occurred (78 AAA-related).  The 30-day operative mortality was 7.3 % in the EVAR group.  However, this group later demonstrated a significant advantage in terms of AAA-related mortality, but this became apparent only after 4 years: overall adjusted HR 0.53 (95 % CI: 0.32 to 0.89), p = 0.02.  Sadly, this advantage did not result in any benefit in terms of all-cause mortality: adjusted HR 0.99 (95 % CI: 0.78 to 1.27), p = 0.97.  Overall, EVAR was more expensive than no intervention (mean difference of £10,222) and not found to be cost-effective.  The authors concluded that EVAR offers a clear operative mortality benefit over open repair in patients fit for both procedures, but this early benefit is not translated into a long-term survival advantage.  Among patients unfit for open repair, EVAR is associated with a significant long-term reduction in AAA-related mortality but this does not appear to influence all-cause mortality.

Di and colleagues (2013) noted that the development of endovascular technology has led to the introduction of FEVAR to treat para-renal abdominal aortic aneurysms (PRAAAs) that have been deemed unsuitable for standard endovascular repair.  These investigators performed a systematic review and meta-analysis of data from the literature to determine the outcomes of the fenestrated technology.  The MEDLINE, EMBASE, and Cochrane databases were searched to identify all studies published in English between January 1996 and May 2011 that reported on FEVAR for PRAAAs.  Separate meta-analyses were performed for primary outcomes (i.e., 30-day mortality, technical success rate, primary target vessel patency rate, and 12-month patency rate) and secondary outcomes (i.e., re-intervention rate, target renal artery occlusion rate, and post-operative permanent dialysis rate).  Subgroup analyses were performed to determine whether there were differences in outcomes between varying types of studies (prospective or retrospective).  Regression analyses were performed to explore associations between outcomes and varying factors (i.e., mid-date of study, study size, and procedure time).  A total of 12 studies conducted between 2006 and 2011 and consisting of a total of 776 cases of FEVAR were enrolled.  The pooled estimate for 30-day mortality was 2.52 % (95 % CI: 1.55 to 4.08).  Technical success was measured to be 92.8 % (95 % CI: 87.5 to 96.0).  Primary target vessel patency was 98.3 % (95 % CI: 97.4 to 98.8).  Twelve-month target vessel patency was 94.5 % (95 % CI: 92.1 to 96.2).  The post-operative re-intervention rate was 17.6 % (95 % CI: 12.0 to 25.1).  The target renal artery occlusion rate was 6.1 % (95 % CI: 4.1 to 8.8).  The post-operative permanent dialysis rate was 2.6 % (95 % CI: 1.5 to 4.4).  Subgroup analyses found no significant differences between the major outcomes of the retrospective studies and the prospective studies.  Regression analyses suggested that large series had higher 12-month target vessel patency rates than small series.  The authors concluded that this study revealed that FEVAR treatment for PRAAAs has acceptable early and mid-term outcomes.

Dijkstra et al (2014) noted that in the past decennium, the management of short-neck infra-renal and juxta-renal aortic aneurysms with FEVAR has been shown to be successful, with good early and mid-term results.  Recently, a new fenestrated device, the fenestrated Anaconda (Vascutek, Renfrewshire, Scotland), was introduced.  These researchers presented the current Dutch experience with this device.  A prospectively held database of patients treated with the fenestrated Anaconda endograft was analyzed.  Decision to treat was based on current international guidelines.  Indications for FEVAR included an AAA with unsuitable neck anatomy for EVAR.  Planning was performed on computed tomography angiography images using a 3-D work-station.  Between May 2011 and September 2013, a total of 25 patients were treated in 8 institutions for juxta-renal (n = 23) and short-neck AAA (n = 2).  Median AAA size was 61 mm (59 to 68.5 mm).  All procedures except 1 were performed with bifurcated devices.  A total of 56 fenestrations were incorporated, and 53 (94.6 %) were successfully cannulated and stented.  One patient died of bowel ischemia caused by occlusion of the superior mesenteric artery.  On completion angiography, 3 type I endoleaks and 7 type II endoleaks were observed.  At 1 month of follow-up, all endoleaks had spontaneously resolved.  Median follow-up was 11 months (range of 1 to 29 months).  There were no aneurysm ruptures or aneurysm-related deaths and no re-interventions to date.  Primary patency at 1 month of cannulated and stented target vessels was 96 %.  The authors concluded that initial and short-term results of FEVAR using the fenestrated Anaconda endograft are promising, with acceptable technical success and short-term complication rates.  Moreover, they stated that growing experience and long-term results are needed to support these findings.

Raux et al (2014) stated that the benefit of FEVAR compared with open surgical repair (OSR) of complex AAAs (CAAAs) is unknown.  These researchers compared 30-day outcomes of these procedures from 2 high-volume centers where FEVAR was undertaken for high-risk patients.  Patients undergoing FEVAR with commercially available devices and OSR of CAAAs (total supra-renal/supra-visceral clamp position) were propensity-matched by demographic, clinical, and anatomic criteria to identify similar patient cohorts.  Peri-operative outcomes were evaluated using uni-variate and multi-variate methods.  From July 2001 to August 2012, a total of 59 FEVAR and 324 OSR patients were identified.  After 1:4 propensity matching for age, gender, hypertension, congestive heart failure, coronary disease, chronic obstructive pulmonary disease, stroke, diabetes, pre-operative creatinine, and anticipated/actual aortic clamp site, the study cohort consisted of 42 FEVARs and 147 OSRs.  The most frequent FEVAR construct was 2 renal fenestrations, with or without a single mesenteric scallop, in 50 % of cases.  An average of 2.9 vessels were treated per patient.  Uni-variate analysis demonstrated FEVAR had higher rates of 30-day mortality (9.5 % versus 2 %; p = 0.05), any complication (41 % versus 23 %; p = 0.01), procedural complications (24 % versus 7 %; p < 0.01), and graft complications (30 % versus 2 %; p < 0.01).  Multi-variable analysis showed FEVAR was associated with an increased risk of 30-day mortality (OR, 5.1; 95 % CI: 1.1 to 24; p = 0.04), any complication (OR, 2.3; 95 % CI: 1.1 to 4.9; p =0 .01), and graft complications (OR, 24; 95 % CI: 4.8 to 66; p < 0.01).  The authors concluded that FEVAR, in this 2-center study, was associated with a significantly higher risk of peri-operative mortality and morbidity compared with OSR for management of CAAAs.  These data suggested that extension of the paradigm shift comparing EVAR with OSR for routine AAAs to patients with CAAAs is not appropriate.  Moreover, they stated that further study to establish proper patient selection for FEVAR instead of OSR is needed before widespread use should be considered.

In a Cochrane review, Jackson et al (2014) compared the clinical outcomes of percutaneous access with standard femoral artery access in elective bifurcated abdominal EVAR.  The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched their Specialised Register (last searched July 2013), CENTRAL (2013, Issue 6) and clinical trials databases.  Reference lists of retrieved articles were checked.  Only RCTs were considered.  The primary intervention was a totally percutaneous endovascular repair.  All device types were considered.  This was compared against standard femoral artery endovascular repair.  Only studies investigating elective repairs were considered.  Studies reporting emergency surgery for a rAAA and those reporting aorto-uni-iliac repairs were excluded.  All data were collected independently by 2 review authors.  Owing to the small number of trials identified, no formal assessment of heterogeneity or sensitivity analysis was conducted.  Only 1 trial met the inclusion criteria, involving a total of 30 participants, 15 undergoing the percutaneous technique and 15 treated by the standard femoral cut-down approach.  There were no significant differences between the 2 groups at baseline.  No mortality or failure of aneurysm exclusion was observed in either group.  Three wound infections occurred in the standard femoral cut-down group, whereas none was observed in the percutaneous group.  This was not statistically significant.  Only 1 major complication was observed in the study, a conversion to the cut-down technique in the percutaneous access group.  No long-term outcomes were reported.  One episode of a bleeding complication was reported in the percutaneous group.  Significant differences were detected in surgery time (percutaneous 86.7 ± 27 minutes versus conventional 107.8 ± 38.5 minutes; p < 0.05). The included study had a small sample size and failed to report adequately the method of randomization, allocation concealment and the pre-selected outcomes.  The authors concluded that only 1 small study was identified, which did not provide adequate evidence to determine the safety and effectiveness of the percutaneous approach compared with endovascular aneurysm repairs.  This review has identified a clear need for further research into this potentially beneficial technique.  One ongoing study was identified in the search, which may provide an improved evidence base in the future.

Glebova et al (2015) noted that a recent prospective study found that FEVAR was safe and effective in appropriately selected patients at experienced centers. As this new technology is disseminated to the community, it will be important to understand how this technology compares with standard EVAR. These researchers compared the outcomes of FEVAR versus EVAR of AAAs. The American College of Surgeons-National Surgical Quality Improvement Program database from 2005 to 2012 was queried for AAAs (International Classification of Diseases, ninth Revision code 441.4). Patients were stratified according to procedure (FEVAR versus EVAR). A bi-variate analysis was done to assess pre-operative and intra-operative risk factors for post-operative outcomes; 30 -day post-operative mortality and complication rates were described for each procedure type. Multi-variable logistic regression was performed to assess the association between the type of procedure and the risk of post-operative complications. A total of 458 patients underwent FEVAR and 19,060 patients underwent EVAR for AAA. Patients undergoing FEVAR were older (p = 0.02) and less likely to have a bleeding disorder (p = 0.046). Otherwise, the incidence of co-morbidities in both groups was similar. Fenestrated EVAR was associated with increased median operative time (156 versus 137 minutes; p < 0.001), and average post-operative length of stay (3.3 versus 2.8 days; p = 0.03). There was a statistically significant increase in overall complications (23.6 % versus 14.3 %; p < 0.001) and post-operative transfusions (15.3 % versus 6.1 %, p < 0.001) and trends toward increased cardiac complications (2.2 % versus 1.3 %; p = 0.09) and the need for dialysis (1.5 % versus 0.8 %; p = 0.08) in the FEVAR group. Mortality (2.4 % versus 1.5 %; p = 0.12) was not statistically different. On multi-variable analysis, FEVAR remained independently associated with the need for post-operative transfusions when operative time was less than 75th percentile (adjusted OR, 1.72; 95 % CI: 1.09 to 2.72; p = 0.02) as well as when operative time was greater than 75th percentile for respective procedures (adjusted OR, 5.33; 95 % CI: 3.55 to 8.00; p < 0.001). The authors concluded that patients undergoing FEVAR are more likely than patients undergoing EVAR to receive blood transfusions post-operatively and are more likely to sustain post-operative complications. They noted that although mortality was similar, trends toward increased cardiac and renal complications may suggest the need for judicious dissemination of this new technology. They stated that future research with larger number of FEVAR cases are needed to determine if these associations remain.

Capoccia and Riambau (2015) stated that inflammatory AAA (IAAA) is a rare but potentially life-threatening condition that is characterized by marked thickening of the aortic wall, peri-aneurysmal and retro-peritoneal fibrosis, and dense adhesions of adjacent abdominal organs. The pathogenesis of IAAA remains an enigma. The principal objective of invasive or surgical therapy of AAAs is prevention or correction of aortic rupture. Prevention or treatment of AAA rupture by open or endovascular repair is proven by numerous studies published in the literature. However, treatment of IAAA poses a different challenge to surgeons compared with traditional atherosclerotic AAA because of the potential for iatrogenic injury in open repair or, alternatively, potential increased inflammatory response to endoprosthesis implantation. These investigators evaluated the effects of elective endovascular versus open repair for IAAA. The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator (TSC) searched the Specialised Register (April 2015) and the Cochrane Register of Studies (CRS) (Issue 3, 2015). The TSC searched trial databases for details of ongoing and unpublished studies. The authors sought all published and unpublished RCTs, quasi-RCTs and controlled clinical trials comparing results of elective endovascular or open repair of IAAAs without language restriction. Both review authors independently assessed studies identified for potential inclusion in the review. They planned to conduct data collection and analysis in accordance with the Cochrane Handbook for Systematic Review of Interventions. These researchers identified no studies that met the inclusion criteria. The authors concluded that they found no published RCTs, quasi RCTs or controlled clinical trials comparing open repair and elective endovascular repair for IAAA, assessing immediate (30-day), intermediate (up to 1-year follow-up) and long-term (more than 1-year follow-up) mortality or complications rates. They stated that high-quality studies evaluating the best treatment for inflammatory abdominal aneurysm repair are needed.

Walker et al (2015) reported their long-term experience with type II endoleaks (T2Ls) management in a large multi-center registry. Between 2000 and 2010, a total of 1,736 patients underwent EVAR, and these investigators recorded the incidence of T2L. Primary outcomes were mortality and aneurysm-related mortality (ARM). Secondary outcomes were change in aneurysm sac size, major adverse events, and re-intervention. During the follow-up (median of 32.2 months; interquartile range [IQR] of 14.2 to 52.8 months), T2L was identified in 474 patients (27.3 %). There were no late AAA ruptures attributable to a T2L. Overall mortality (p = 0.47) and ARM (p = 0.26) did not differ between patients with and without T2L. Sac growth (median of 5 mm; IQR of 2 to 10 mm) was seen in 213 (44.9 %) of the patients with T2L. Of these patients with a T2L and sac growth, 36 (16.9 %) had an additional type of endoleak. Of all patients with T2L, 111 (23.4 %) received re-interventions, including 39 patients who underwent multiple procedures; 74 % of the re-interventions were performed in patients with sac growth. Re-interventions included lumbar embolization in 66 patients (59.5 %), placement of additional stents in 48 (43.2 %), open surgical revision in 14 (12.6 %), and direct sac injection in 22 (19.8 %). The re-intervention was successful in 35 patients (31.5 %). After patients with other types of endoleak were excluded, no difference in overall all-cause mortality (p = 0.57) or ARM (p = 0.09) was observed between patients with T2L-associated sac growth who underwent re-intervention and those in whom T2L was left untreated. The authors concluded that in their multi-center EVAR registry, overall all-cause mortality and ARM were unaffected by the presence of a T2L. Moreover, patients who were simply observed for T2L-associated sac growth had aneurysm-related outcomes similar to those in patients who underwent re-intervention. They stated that their future work will investigate the most cost-effective ways to select patients for intervention besides sac growth alone.

An UpToDate review on "Endovascular repair of abdominal aortic aneurysm" (Chaer, 2015) states that "Contraindications – Endovascular repair of AAA is contraindicated in patients who do not meet the anatomic criteria required to place any of the available endografts. Adverse anatomic features include suprarenal or juxtarenal AAA, small caliber vessels, circumferential aortic calcification, and extensive tortuosity. Depending upon the location of the main and accessory renal arteries, endovascular repair may also be contraindicated for the management of AAA associated with horseshoe kidney. A variety of next-generation devices are being developed to treat suprarenal and juxtarenal abdominal aortic aneurysms. A relative contraindication to endovascular aneurysm repair (EVAR) is the inability to comply with the required post-EVAR surveillance. Whether younger patients (less than 60 years of age) who are not at high risk for open surgery should undergo open surgical repair versus EVAR remains controversial. Surveillance over an extended period of time exposes the patient to greater levels of cumulative radiation, and EVAR does not completely eliminate the risk of future aortic rupture. Guidelines from major medical and surgical societies emphasize an individualized approach when choosing endovascular repair, taking into account the patient's age and risk factors for perioperative morbidity and mortality".

CT Surveillance after Endovascular (Stent) Aortic Repair

MedSolutions guidelines recommend CT surveillance after endovascular (stent) aortic repair at 1 month, 6 months, and 12 months following repair, then every year.

Multi-Branched Stent-Grafts

Armstrong and associates (2014) stated that patients with large AAAs are usually offered reparative treatment given the high mortality risk. There is uncertainty about how to treat juxta-renal AAAs (JRAAAs) or TAAAs.  Endovascular repair of an abdominal aortic aneurysm (EVAR) is often seen as safer and easier than OSR.  However, endovascular treatment of JRAAAs or TAAAs requires specially manufactured stent grafts, with openings to allow blood to reach branches of the aorta.  Commissioners are receiving increasing requests for fenestrated EVAR (fEVAR) and branched EVAR (bEVAR), but it is unclear whether or not the extra cost of fEVAR or bEVAR is justified by advantages for patients.  In a systematic review and cost-effectiveness analysis, these investigators evaluated the clinical safety, effectiveness, and cost-effectiveness of fEVAR and bEVAR in comparison with conventional treatment (i.e., no surgery) or OSR for 2 populations:

1. JRAAAs and
2. TAAAs. 

Resources were searched from inception to October 2013, including Medline (OvidSP), Embase (OvidSP) and the Cochrane Central Register of Controlled Trials (Wiley) and, additionally, for cost-effectiveness, NHS Economic Evaluation Database (NHS EED; Wiley) and EconLit (EBSCOhost).  Conference abstracts were also searched.  Studies were included based on an intervention of either fEVAR or bEVAR and a comparator of either OSR or no surgery.  For clinical effectiveness, observational studies were excluded only if they were not comparative, i.e., explicitly selected on the basis of prognosis.  For clinical effectiveness, searches retrieved 5,253 records before de-duplication.  Owing to overlap between the databases, 1,985 duplicate records were removed.  Of the remaining 3,268 records, based on titles and abstracts, 3,244 records were excluded, leaving 24 publications to be ordered.  All 24 studies were excluded as none of them satisfied the inclusion criteria – 16 studies were excluded on study design, 6 on intervention and 2 on comparator; 5 out of 16 studies excluded on study design reported a comparison.  However, all of the studies acknowledged that they had groups that were not comparable at baseline given that they had selectively assigned younger, fitter patients to OSR.  Therefore, these studies were considered "non-comparative".  For cost-effectiveness, searches identified 104 references before de-duplication.  Owing to overlap between the databases, 34 duplicate records were removed.  Of the remaining 70 records, 7 were included for the full assessment based on initial screening.  After a full-text review, no studies were included.  Because of the lack of clinical effectiveness evidence and difficulty in estimating costs given the rapidly changing and variable technology, a cost-effectiveness analysis (CEA) was not performed.  Instead a detailed description of modelling methods was provided.  The authors concluded that despite a thorough search, no studies could be found that met the inclusion criteria.  All studies that compared either fEVAR or bEVAR with either OSR or no surgery explicitly selected patients based on prognosis, i.e., essentially the populations for each comparator were not the same.  The authors recommended that at least 1 clinical trial to provide an unbiased estimate of effect for fEVAR/bEVAR compared with OSR or no surgery.  This trial should also collect data for a CEA.

Michel and co-workers (2015) compared 30-day outcomes and costs of fEVAR, bEVAR and OSR for the treatment of complex AAA and TAAA. The multi-center, prospective, registry WINDOW Trial was designed to evaluate fEVAR/bEVAR in high-risk patients with para-renal AA (PRAA)/JRAAA, and infra-diaphragmatic and supra-diaphragmatic TAAA.  A control group of patients treated by OSR was extracted from the national hospital discharge database.  The primary end-point was 30-day mortality; secondary end-points included severe complications, length of stay, and costs.  Mortality was assessed by survival analysis and univariate and multivariate Cox regression analyses using pre- and post-operative characteristics.  Bootstrap methods were used to estimate the cost-effectiveness of fEVAR/bEVAR versus OSR.  A total of 268 cases and 1,678 controls were included.  There was no difference in 30-day mortality (6.7 % versus 5.4 %, p = 0.40), but costs were higher with fEVAR/bEVAR (€38,212 versus €16,497, p < 0.001).  After group stratification, mortality was similar with both treatments for PRAA/JRAAA (4.3 % versus 5.8 %, p = 0.26) and supra-diaphragmatic TAAA (11.9 % versus 19.7 %, p =0 .70), and higher with fEVAR/bEVAR for infra-diaphragmatic TAAA (11.9 % versus 4.0 %, p = 0.010).  Costs were higher with fEVAR/bEVAR for PRAA/JRAAA (€34,425 versus €14,907, p < 0.0001) and infra-diaphragmatic TAAA (€37,927 versus €17,530, p < 0.0001), but not different for supra-diaphragmatic TAAA (€54,710 versus €44,163, p = 0.18).  The authors concluded that fEVAR/bEVAR did not appear justified for patients with PRAA/JAAAA and infra-diaphragmatic TAAA fit for OSR; but may be an attractive option for patients with PARR/JRAAA not eligible for surgery and patients with supra-diaphragmatic TAAA.

Eagleton and colleagues (2016) evaluated the technical and clinical outcomes of fEVAR/bEVAR for extensive type II and III TAAA. Data from 354 high-risk patients enrolled in a physician-sponsored investigational device exemption (IDE) trial (2004 to 2013) undergoing fEVAR/bEVAR for type II and III TAAA were evaluated.  Technical success, peri-operative clinical outcomes, and mid-term outcomes (36 months) for branch patency, re-intervention, aneurysm-related death, and all-cause mortality were analyzed.  Data are presented as mean ± standard deviation (S.D.) and were assessed using Kaplan-Meier, univariate, and multivariate analysis; fEVAR/bEVAR incorporating 1,305 fenestration/branches were implanted with 96 % of target vessels successfully stented.  Completion aortography showed 2.8 % patients had a type I or III endoleak.  Procedure duration (6.0 ± 1.7 versus 5.5 ± 1.6 hours; p < 0.01) and hospital stay (13.1 ± 10.1 versus 10.2 ± 7.4 days; p < 0.01) were longer for type II TAAA.  Peri-operative mortality was greater in type II repairs (7.0 % versus 3.5 %; p < 0.001).  Permanent spinal cord ischemia (SCI) occurred in 4 % and renal failure requiring hemodialysis occurred in 2.8 % of patients; 27 branches (7.6 %) required re-intervention for stenosis or occlusion; and celiac artery, superior mesenteric artery, and renal artery secondary patency at 36 months was 96 % (95 % CI: 0.93 to 0.99), 98 % (95 % CI: 0.97 to 1.0), and 98 % (95 % CI: 0.96 to 1.0), respectively.  A total of 80 endoleak repairs were performed in 67 patients, including 55 branch-related endoleaks, 4 type Ia, 5 type Ib, and 15 type II endoleaks.  At 36 months, freedom from aneurysm-related death was 91 % (95 % CI: 0.88 to 0.95), and freedom from all-cause mortality was 57 % (95 % CI: 0.50 to 0.63).  The treatment of type II TAAA (p < 0.01), age (p < 0.01), and chronic obstructive pulmonary disease (p < 0.05) negatively affected survival.  The authors concluded that fEVAR/bEVAR is a robust therapeutic option for patients at increased risk for conventional repair of extensive TAAAs.  Technical success and branch patency were excellent, but some patients will require re-intervention for branch-related endoleak.  Aneurysm extent portends a higher risk of peri-operative and long-term morbidity and mortality.  They stated that additional efforts are needed to improve outcomes and understand the utility of this therapeutic option in the general TAAA population.

In a systematic review and meta-analysis, Hu and colleagues (2016) evaluated the available literature on endovascular repair of TAAA and para-renal aortic aneurysm (PRAA) using multi-branched stent-grafts. Medline, Embase, and Cochrane databases were searched between January 2001 and June 2015 to identify articles related to the use of multi-branched stent-grafts for the treatment of TAAA and PRAA.  Articles with less than 4 cases and those on juxta-renal aortic aneurysms were excluded.  Meta-analyses were conducted to evaluate 30-day mortality, all-cause mortality, SCI, renal insufficiency, endoleak, target vessel patency, and re-intervention.  Of 370 articles screened, only 4 articles encompassing 185 patients (mean age of 71.1 years; 137 men) were aligned with the inclusion criteria.  There were 23 PRAAs; the mean aneurysm diameter was 64.5 mm.  The Crawford TAAA classification was 10 type I, 47 type II, 37 type III, 58 type IV, and 9 type V; there was 1 Stanford type B dissection in association with a large TAAA.  Results of the meta-analyses are reported as proportions and 95 % CI.  Pooled analysis indicated a technical success rate of 98.9 %.  As study heterogeneity was significant, random effects models were used for meta-analysis.  The rate for 30-day mortality was 9 % (95 % CI: 3 % to 19 %), for all-cause mortality 27 % (95 % CI: 17 % to 38 %), endoleaks 10 % (95 % CI: 1 % to 25 %), target vessel patency 98 % (95 % CI: 95 % to 99 %), SCI 17 % (95 % CI: 1 % to 26 %), irreversible SCI 6 % (95 % CI: 3 % to 10 %), renal insufficiency 15 % (95 % CI: 0.8 % to 41 %), and re-interventions 21 % (95 % CI: 4 % to 47 %).  The authors concluded that use of multi-branched stent-grafts in the treatment of TAAAs and PRAAs appeared to be feasible and safe based on satisfactory early outcomes in the limited literature available to date.  Moreover, they stated that long-term surveillance and further studies are needed to determine the durability of this technique.

Furthermore, an UpToDate review on "Endovascular repair of abdominal aortic aneurysm" (Chaer, 2016) states that "Advanced devices and techniques – When aneurysmal disease is more extensive, involving the visceral vessels proximally or associated with common or hypogastric artery aneurysms, the complexity of the required endovascular or open repair increases. Fenestrated and branched graft technology is under investigation to manage more challenging anatomy without the need for surgical debranching.  The early results using these endografts have been promising, with high rates of successful exclusion of juxta-renal and thoracoabdominal aneurysms, but with an increased risk of visceral artery or stent-branch occlusion".

Intravenous Heparin During Ruptured Abdominal Aortic Aneurysmal Repair

Lammy and colleagues (2016) noted that there have been enormous advances in the screening, diagnosis, intervention and overall prognosis of AAAs in the last decade, but despite these, rAAAs still cause around 3,500 to 6,000 deaths in England and Wales each year.  Open repair remains standard treatment for rAAA in most centers but increasingly EVAR is being adopted.  This has a 30-day post-operative mortality of 40 %, which has remained static despite surgical, anesthetic and critical care advances.  One significant change to current practice for elective repairs of AAAs, as opposed to emergency repairs of rAAAs, has been the introduction of intravenous heparin.  This provides a protective effect against cardiac and thrombotic disease in the post-operative period.  This practice has not gained widespread acceptance for emergency repairs of rAAA even though a reduction in mortality and morbidity has been demonstrated in elective repairs.  In a Cochrane review, these researchers examined the effect of intravenous heparin on all-cause mortality in rAAA management in patients undergoing an emergency repair.  The secondary objectives were to evaluate the effect of intravenous heparin in rAAA management on the incidence of general arterial disease (e.g., cardiovascular, cerebral, pulmonary and renal pathologies) in patients undergoing emergency repair.  The Cochrane Vascular Information Specialist (CIS) searched the Specialized Register (December 2015).  In addition the CIS searched CENTRAL;2015, Issue 11).  The CIS searched clinical trials registries for details of ongoing or unpublished studies.  These researchers sought all published and unpublished RCTs and controlled clinical trials (CCTs) of intravenous heparin in rAAA repairs (including parallel designs).  Two review authors independently assessed studies identified for potential inclusion in the review.  They used standard methodological procedures in accordance with the Cochrane Handbook for Systematic Review of Interventions.  They identified no RCTs or CCTs that satisfied the inclusion criteria.  The authors concluded that they identified no RCTs or CCTs of intravenous heparin in rAAA repairs (including parallel designs).  Thus, they were unable to evaluate the effect of intravenous heparin on all-cause mortality and incidence of general arterial disease in patients undergoing an emergency repair.  They stated that a RCT is needed to address this question in rAAA management as there is no high quality evidence.

Pre-Operative Inferior Mesenteric Artery Embolization to Reduce the Rate of Type II Endoleak Following Endovascular Abdominal Aortic Aneurysm Repair

Brown and associates (2016) stated that type II endoleaks are the most common endovascular complications of EVAR; however, there has been a divided opinion regarding their significance in EVAR.  Some advocate a conservative approach unless there is clear evidence of sac expansion, while others maintain early intervention is best to prevent adverse late outcomes such as rupture.  There is a lack of Level I Evidence in this challenging group of patients, and due to a low event rate of complications, large numbers of patients would be needed in well-designed trials to fully understand the natural history of type II endoleak.  These investigators noted that due to a lack of evidence regarding the natural history of type II endoleaks and their association with adverse outcomes such as sac expansion and rupture, intervention is typically offered for persistent endoleaks and for those which demonstrate sac expansion (greater than 10 mm) or increased intra-sac pressure.  Unfortunately, optimal thresholds are not clear.  Moreover, they stated that future studies should aim to compare not only different approaches to the treatment of type II endoleak, but also different embolents.  More focus is needed on long-term outcomes and complications rather than technical success alone.  A multi-center registry of type II endoleak intervention and outcomes would be ideal to uncover solutions to some of the remaining challenges in the management of this challenging group of patients.

Manunga and colleagues (2017) noted that type II endoleak is the most commonly encountered endoleak after EVAR.  Some have advocated pre-operative inferior mesenteric artery (IMA) embolization as a method for reducing the incidence of this endoleak, but controversies exist.  These researchers examined the impact of IMA embolization using a meta-analysis of currently available studies combined with their own experience.  They conducted an institutional review board (IRB)-approved, retrospective analysis of all patients undergoing IMA embolization before EVAR between the years 2010 and 2015 and used as a control a similar group of patients with patent IMA.  These investigators divided patients from their own experience and 5 other studies into 2 groups:

1. those who did not undergo IMA embolization (control) before EVAR, and
2. those who did.

Rates of type II endoleaks, aneurysm sac regression, and secondary interventions were analyzed.  A total of 620 patients from 6 studies were analyzed, including 258 patients who underwent an attempted IMA embolization before EVAR with a cumulative success rate of 99.2 % (range of 93.8 % to 100 %).  There was 1 fatality associated with IMA embolization.  A meta-analysis showed that pre-operative IMA embolization protected against type II endoleaks compared to the control group (OR, 0.31 [0.17 to 0.57]; p < 0.001, I2 = 43 %).  Furthermore, the rate of secondary intervention was significantly lower in the treatment group (OR, 0.12 [0.004 to 0.36]; p < 0.001, I2 = 0 %).  After IMA embolization, type II endoleak resulted from patent lumbar arteries in all 62 patients with persistent endoleak.  The authors concluded that pre-operative embolization of the IMA protected against the development of type II endoleaks and secondary interventions and may potentially lead to a rapid aneurysm sac regression.  The procedure can be performed with a high technical success rate and minimal complications and should be considered in patients with IMA greater than 3 mm before EVAR.  Moreover, they stated that a randomized trial is needed to clearly delineate the clinical significance of this technique.

Fenestrated Prosthesis for Repair of Abdominal Aortic Aneurysms

Graves and Jackson (2015) noted that endovascular abdominal aortic aneurysm repair (EVAR) provides an attractive alternative to traditional open techniques.  Endovascular repair is frequently limited by aortic aneurysm neck angulation, the absence of an adequate infra-renal neck, and the need for internal iliac preservation.  Several devices have been created to incorporate visceral artery segments as well as preserve the internal iliac artery, thus broadening the patient population suited for endovascular repair.  These researchers reviewed the current literature regarding fenestrated devices, branch devices, off-the-shelf devices, and physician-modified devices.  They also highlighted the iliac branch stent grafts currently on trial for internal iliac artery preservation.  The authors concluded that data thus far have suggested that these devices will be both a safe and effective option for anatomically challenging abdominal aortic aneurysms (AAAs).  They noted that fenestrated and branched stent grafts have greatly broadened therapeutic options for aortic aneurysmal disease and their clinical use will expand as technologies are advanced

Glorion et al (2016) stated that despite technical advances of fenestrated and branched endografts, endovascular exclusion of aneurysms involving renal, visceral, and/or supra-aortic branches remains a challenge.  In-situ fenestration (ISF) of standard endografts represents another endovascular means to maintain perfusion to such branches.  These investigators reviewed current indications, technical descriptions, and results of ISF.  A review of the English language literature was performed in Medline databases, Cochrane Database, Web of Science, and Scopus using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines.  A total of 67 relevant papers were selected; 33 papers were excluded, leaving 34 articles as the basis of the present review.  Most experimental papers evaluated ISF feasibility and assessed the consequences of ISF on graft fabric.  Regarding clinical papers, 73 ISF procedures have been attempted in 58 patients, including 26 (45 %) emergent and 3 (5 %) bailout cases; 65 (89 %) ISF were located at the level of the arch, and 8 (11 %) in the abdominal aorta.  Graft perforation was performed by physical, mechanical, or unspecified means in 33 (45 %), 38 (52 %), and 2 vessels (3 %), respectively.  ISF was technically successful in 68/73 (93 %) arteries.  At 30 days, 2 (3.4 %) patients died in the setting of an aorto-bronchial fistula and an aorto-esophageal fistula, respectively.  No post-operative death, major complication, or endoleak was seen as secondary to the ISF procedure.  With follow-up between 0 and 72 months, 4 (6.9 %) late deaths were noted, unrelated to the aorta; 1 (1.7 %) LSA stent was stenosed without symptoms.  The authors concluded that although there may be publication bias, multiple techniques were described to perform ISF with satisfactory short-term results.  Long-term data remain scarce.  They stated that aortic endograft ISF is an off-label procedure that should not be used outside emergent bailout techniques or investigational studies.  These researchers stated that a comparison with alternative techniques of preserving aortic side branches is needed.

Blankensteijn et al (2017) noted that the fenestrated Anaconda endograft (Vascutek, Renfrewshire, Scotland) was introduced in 2010 and showed promising short-term results with high technical success and low morbidity rates.  These researchers presented the mid-term results, with a minimum of 12 months follow-up, for all patients treated with the fenestrated Anaconda endograft in the Netherlands.  Patients treated with the fenestrated Anaconda endograft between May 2011 and February 2015 were included.  Follow-up consisted of computed tomography angiography at 1 month and 1 year, and duplex ultrasound yearly thereafter with additional computed tomography angiography if indicated using a standard protocol.  A total of 60 patients were included; 48 patients (80.0 %) were treated for juxta-renal aneurysms, and 12 (20.0 %) were short-neck infra-renal aneurysms.  Mean aneurysm size was 64 ± 9 mm.  A total of 140 fenestrations were incorporated.  Median follow-up was 16.4 months (inter-quartile range [IQR], 11.9 to 27.4).  The 30-day mortality was 3.4 % (n = 2).  Kaplan-Meier estimates for 1-year, 2-year, and 3-year survival were 91.4 %, 89.5 %, and 86.3 %, respectively, without aneurysm-related mortality during follow-up.  Main body primary and secondary endograft patencies were 98.3 % and 100 %, respectively.  Target vessel primary and secondary patencies were 95.0 % and 98.6 %, respectively.  Early type IA endoleaks occurred in 7 patients (11.7 %) and spontaneously resolved in all patients.  At 1-year follow-up 4 (6.7 %) type II endoleaks persisted; 1 patient experienced aneurysm rupture because of a late type III endoleak attributable to a dislodged renal stent and subsequently underwent successful conversion to open surgery.  The authors concluded that fenestrated Anaconda is a viable therapeutic option for complex abdominal aortic aneurysms.  Acceptable mortality and morbidity and low re-intervention rates contribute to good mid-term results.  Occurrence of early type I endoleak was relatively common, but these resolved spontaneously in all patients. Long-term follow-up data are needed.

Timaran et al (2017) stated that fenestrated endovascular aneurysm repair (FEVAR) is an alternative to open repair of complex aortic aneurysms.  Despite promising short-term results, the technical complexities of this procedure remain a considerable challenge.  The risk of technical failure with loss of visceral or renal arteries is ubiquitous even in the most experienced hands, and thus many patients with unfavorable anatomy are frequently denied FEVAR.  These researchers have adopted a new technique for FEVAR that involves retrograde brachial artery access and step-wise deployment of the endograft during target vessel catheterization, overcoming many anatomic limitations encountered from a trans-femoral (TF) approach.  This technique, termed sequential catheterization amid progressive endograft deployment, has become the authors’ preferred approach for FEVAR.  Moreover, these investigators noted that currently available Food and Drug Administration-approved fenestrated endografts may not be amenable to sequential catheterization amid progressive endograft deployment as this technique requires pre-loaded wires incorporated into the endografts.

Falkensammer et al (2017) FEVAR allows an extension of the proximal sealing zone above the renal arteries to an adequate, healthier segment of the aorta.  This feature makes FEVAR an option to treat patients with a diseased aortic neck or type Ia endoleak after EVAR.  These investigators presented a single-center experience with FEVAR for patients with an abdominal aortic endograft in-situ compared with primary FEVAR.  A prospectively held database on FEVAR patients treated with the fenestrated Anaconda device (Vascutek/Terumo, Inchinnan, Scotland, United Kingdom) at the authors’ institution was screened for individuals who had previously undergone EVAR.  Between April 1, 2013, and July 31, 2016, a total of 94 fenestrated Anaconda devices were implanted at the authors’ institution; 12 patients with prior EVAR were treated for pathology of the proximal neck: type I endoleak (n = 7), for stent migration with aneurysm progression but no visible endoleak (n = 2), and progressive aortic disease at the level of the visceral segment (n = 3).  When re-do cases and primary FEVARs were compared, primary technical success rates were 58.3 % and 87.8 % (p = 0.02) and primary functional success rates were 91.7 % and 95.1 %, respectively (p = 0.62).  Peri-operative rate of major deployment-related (14.6 % and 16.7 %) and systemic complications (8.5 % and 8.3 %) as well as 30-day mortality (6.1 % and 0 %; p = 0.5) were comparable between groups.  After an average follow-up interval of 10 months (range of 0 to 43 months), no late occlusions of connecting stents were observed.  The late re-intervention rates were 11.0 % and 16.7 %, respectively (p = 0.57).  The authors concluded that the risk of a failure to cannulate 1 or more visceral arteries through the respective fenestrations was increased in patients who had previously undergone EVAR.  This was most likely caused by increased friction between the fenestrated endograft and the failing graft in-situ, which may impair the adaption of the unsupported Anaconda device to the aortic wall.  As a consequence, fenestrations may not line up perfectly at the respective openings of the visceral or renal arteries, and folding of the fabric may be increased, making cannulation of the fenestrations more difficult.

Georgiadis et al (2017) noted that the establishment use of fenestrated and branched devices to treat complex aortic aneurysms as a first-line management option has been previously reported.  These researchers reviewed the current literature of the use of fenestrated devices to treat complex abdominal and thoraco-abdominal type IV aortic aneurysms as a first-line management option.  A literature search was performed.  This review particularly focused on all the aspects of the use and results of fenestrated stent-grafts (SGs) in patients with complex abdominal and type IV thoraco-abdominal aortic aneurysms and summarized the available evidence.  The use of fenestrated SGs for complex aortic aneurysm disease has grown enormously the last years; SGs with fenestrations, scallops and occasionally branches have to be customized to each patient's anatomy and precisely deployed in-vivo.  Bridging covered stents between the main graft and the target vessels eventually exclude the aneurysm preserving blood flow to vital organs.  Multiple device morphologies have been used incorporating the visceral arteries in various combinations.  High technical success rates and satisfactory peri-operative outcomes were described as well as mid- and long-term success and durability including target vessel and branch stent perfusion, data emerging mainly from high volume specialized centers.  Percentage of target vessel successfully perfused was reported between 90.5 and 100%; 30-day mortality was reported between 0 % and 4.1 % while the lowest type 1 or type 3 endoleak rates were 2.5 % and 1.3 %, respectively.  Migration rates were kept below 3 %.  Renal failure was the most frequent complication reported.  Advances in SG technology have reduced but not eliminated secondary interventions.  Outcomes depend mostly on proximal extension of the disease which increases also the complexity of the repair.  High level of expertise and organizational facilities are required for better mid- and long-term outcomes.  The authors concluded that fenestrated EVAR (fEVAR) has been shown to be safe and effective in the short and mid-term follow-up.  Remaining issues including secondary interventions and the need for follow-up are still within the range of those reported for EVAR.  These, continue to plague fEVAR for complex abdominal or type IV thoraco-abdominal aortic aneurysms.

Farber et al (2017) reported prospective data of an off-the-shelf fenestrated endograft (Zenith p-Branch; Cook Medical, Bloomington, IN) from 4 centers for the treatment of patients with para-renal AAAs.  Data were combined from 4 single-center investigational studies conducted in the United States and Europe.  The p-Branch endograft consists of a proximal off-the-shelf component incorporating a scallop for the celiac artery, a superior mesenteric artery fenestration, and 2 conical pivot fenestrations to preserve flow to the renal vessels.  The device is available in 2 configurations, a left renal fenestration at the same (configuration A) or lower (configuration B) longitudinal position than the right to accommodate varied anatomy of the patients.  Between August 2011 and September 2015, a total of 76 patients (82 % men; mean age of 72 years; 65 elective and 11 emergent) were enrolled, with 55 % implanted with option A and 45 % with B.  The device was deployed successfully in all patients, and stents were placed in all target vessels except in 3 cases (1 elective, 2 emergent): a left kidney was sacrificed in 1 patient, and a right renal artery was left un-stented in 2 patients during the index procedure.  There was no 30-day mortality.  During follow-up (mean of 25 ± 13 months), 10 late deaths occurred (6 elective, 4 emergent; none related to device or procedure), and there were no ruptures or conversions to open repair; 2 patients experienced bowel ischemia; 1 case resolved with non-operative treatment and 1 required superior mesenteric artery and celiac artery angioplasty and stent placement.  Renal artery occlusion occurred in 8patients (11 %) and was deemed procedure related in 63 % (5/8) of these patients; 4 of these were successfully intervened on with preservation of renal function.  The overall renal insufficiency incidence was 7 % (5/76); 1 patient developed renal failure requiring dialysis.  The authors concluded that early results incorporating learning curves for physicians with a new device and delivery system indicated that the use of the Zenith p-Branch device is feasible and safe; long-term follow-up is needed to assess the effectiveness and durability of this treatment strategy and to refine the indications for use.

Oderich et al (2017) examined outcomes of manufactured fenestrated and branched endovascular aortic repair (F-BEVAR) endografts based on supra-celiac sealing zones to treat para-renal aortic aneurysms and thoraco-abdominal aortic aneurysms (TAAAs).  A total of 127 patients (91 men; mean age of 75 ± 10 years old) were enrolled in a prospective, non-randomized, single-center study using manufactured F-BEVAR (November 2013 to March 2015).  Stent design was based on supra-celiac sealing zone in all patients with greater than or equal to 4 vessels in 111 (89 %). Follow-up included clinical examination, laboratory studies, duplex ultrasound, and computed tomography imaging at discharge, 1 month, 6 months, and yearly. End points adjudicated by independent clinical event committee included mortality, major adverse events (any mortality, MI, stroke, paraplegia, acute kidney injury, respiratory failure, bowel ischemia, blood loss of more than 1 L), freedom from re-intervention, and branch-related instability (occlusion, stenosis, endoleak or disconnection requiring re-intervention), target vessel patency, sac aneurysm enlargement, and aneurysm rupture.  There were 47 para-renal, 42 type IV, and 38 type I-III TAAAs with mean diameter of 59 ± 17 mm.  A total of 496 renal-mesenteric arteries were incorporated by 352 fenestrations, 125 directional branches, and 19 celiac scallops, with a mean of 3.9 ± 0.5 vessels per patient.  Technical success of target vessel incorporation was 99.6 % (n = 493/496).  There were no 30-day or in-hospital deaths, dialysis, ruptures or conversions to open surgical repair.  Major adverse events (AEs) occurred in 27 patients (21 %).  Paraplegia occurred in 2 patients (1 type IV, 1 type II TAAAs).  Follow-up was greater than 30 days in all patients, greater than 6 months in 79, and greater than 12 months in 34.  No patients were lost to follow-up.  After a mean follow-up of 9.2 ± 7 months, 23 patients (18 %) had re-interventions (15 aortic, 8 non-aortic), 4 renal artery stents were occluded, 5 patients had type Ia or III endoleaks, and none had aneurysm sac enlargement.  Primary and secondary target vessel patency was 96 % ± 1 % and 98 % ± 0.7 %, respectively at 1 year.  Freedom from any branch instability and any re-intervention was 93 % ± 2 % and 93 % ± 2 % at 1 year, respectively.  Patient survival was 96 % ± 2 % at 1 year for the entire cohort.  The authors concluded that endovascular repair of para-renal aortic aneurysms and TAAAs, using manufactured F-BEVAR with supra-celiac sealing zones, was safe and efficacious; however, long-term follow-up is needed to assess the impact of 4-vessel designs on device-related complications and progression of aortic disease.

Zeinali et al (2018) state that "more complex thoracoabdominal and juxtarenal abdominal aortic aneurysms can now be treated with new stent grafts and techniques. Fenestrated endovascular aortic aneurysm repair (FEVAR) with fenestrated stent grafts was commenced in our center after hundred cases of endovascular aortic repair, and so far 4 serial complex cases deemed inoperable (2 juxtarenal abdominal aortic aneurysms, 1 thoracoabdominal aneurysm, and 1 thoracoabdominal pseudoaneurysm) have been treated with FEVAR. All these patients needed custom-made stent grafts, which were designed and implanted successfully under general anesthesia in the catheterization laboratory. They were followed up for more than 1 year, with a median follow-up period of 23.0 months. There were no major in-hospital or short-term complications. Only 1 patient had midterm unilateral iliac artery thrombosis, which was successfully managed interventionally. Computed tomography angiography at 1 year’s follow-up showed that the stent grafts were patent and their visceral branch cover stents had no endoleak." Due to the limited number of procedures and variety in patients’ conditions and clinical settings, reporting the outcome of every procedure is still demanding. This study was conducted at a single-center with limited number of cases in Iran.

Oderich from the Mayo Clinic (2018) stated that "Endovascular repair of complex aneurysms involving the visceral arteries has become a reality.  Fenestrated stent-grafts are increasingly utilized to treat para-renal and thoraco-abdominal aneurysms.  The technique is safe, effective, and can be performed with high technical success and low risk of complications by experienced physicians.  More than 8,000 patients have been treated by fenestrated and branched stent-grafts and more than 5,500 by iliac branch devices.  Based on results of single-center reports, systematic reviews, and the U.S. prospective trial, technical success is high (greater than 98 %) with low rates of type I and type III endoleak, migration, aneurysm rupture, and conversion to open repair.  Branch patency averages greater than 95 % with covered stents.  These results should serve as a benchmark for comparison with alternative endovascular techniques of branch vessel incorporation, including debranching, snorkel, and physician modified grafts.  Long-term comparison with open surgical repair is still required".

Wang et al (2018) stated that the Zenith Fenestrated (ZFEN; Cook Medical, Bloomington, IN) aortic stent graft system was approved for commercial use by the Food and Drug Administration (FDA) in April 2012.  These researchers report their single-center experience of 100 consecutive patients treated with the ZFEN platform from October 2012 to March 2017.  A retrospective review of their prospectively maintained fenestrated endovascular aneurysm repair (FEVAR) database at a tertiary care academic institution located in the Midwest United States was performed for descriptive analysis.  All continuous variables were reported as a mean ± standard deviation and compared using 2-sided Student t-tests.  Categorical variables were compared using 2-sided Fisher exact tests.  All but 1 of the procedures were elective in nature.  Overall intra-operative characteristics included a mean blood loss (estimated blood loss) of 388 ± 385 ml, fluoroscopy time of 63 ± 30 minutes, radiation dose of 437 ± 272 rad, contrast material volume of 99 ± 36 ml, and operative time of 236 ± 87 minutes.  Average number of visceral arteries stented was 2.1 ± 0.5.  Technical success was achieved in 98 % of the patients.  Statistically significant (p < 0.05) improvement in estimated blood loss (2.1-fold) was observed in the second half of their series.  Interestingly, no improvements were made in terms of fluoroscopy time, radiation exposure, contrast material use, or operative time.  However, procedural difficulty increased in the last half by number of visceral arteries stented as a surrogate (1.9 versus 2.2; p < 0.05).  Mean length of stay (LOS) was 3.6 ± 4.3 days.  Peri-operative mortality at 30 days was 2 %.  Peri-operative morbidity included a 5 % incidence of any bowel ischemia, 1 % of spinal cord ischemia, 3 % of renal failure requiring hemodialysis, 1 % of stroke, and 4 % of myocardial infarction (MI).  Average follow-up was 1.7 ± 1.4 years.  Re-intervention during the follow-up phase was 20 %.  Of the 209 visceral arteries stented, these investigators noted 6 instances of stent thrombosis, 6 of kinking or stenosis, and 1 of stent fracture in follow-up.  Endoleak, most commonly type II, was present or could not be excluded in 15 % of all FEVARs at last available computed tomography angiography (CTA).  The authors concluded that in their experience, FEVAR with the ZFEN system continued to be safe and effective; there was a significant rate of re-intervention observed, and close monitoring is fundamental to maintaining good clinical results.  The main drawbacks of this study were its  retrospective design, a single center study and mid-term results; well-designed studies with long-term follow-up are needed to validate these findings.

Also, an UpToDate review on "Endovascular repair of abdominal aortic aneurysm" (Chaer, 2018a) states that "Advanced devices and techniques – When aneurysmal disease is more extensive, involving the visceral vessels proximally or associated with common or hypogastric artery aneurysms, the complexity of the required endovascular or open repair increases.  Fenestrated and branched graft technology is under investigation to manage more challenging anatomy without the need for surgical debranching.  The early results using these endografts have been promising, with high rates of successful exclusion of juxtarenal and thoracoabdominal aneurysms, but with an increased risk of visceral artery or stent-branch occlusion". 

An UpToDate review on "Endovascular devices for abdominal aortic repair" (Chaer, 2018b) states that "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 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 … 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".

Armstrong et al (2014) noted that patients with large abdominal aortic aneurysms (AAAs) are usually offered reparative treatment given the high mortality risk. The investigators stated that there is uncertainty about how to treat juxtarenal AAAs (JRAAAs) or thoracoabdominal aortic aneurysms (TAAAs). Endovascular repair of an abdominal aortic aneurysm (EVAR) is often seen as safer and easier than open surgical repair (OSR). However, endovascular treatment of JRAAAs or TAAAs requires specially manufactured stent grafts, with openings to allow blood to reach branches of the aorta. The investigators explained that commissioners are receiving increasing requests for fenestrated EVAR (fEVAR) and branched EVAR (bEVAR), but it is unclear whether or not the extra cost of fEVAR or bEVAR is justified by advantages for patients. The investigators conducted a systematic evidence review to assess the clinical effectiveness, safety and cost-effectiveness of fEVAR and bEVAR in comparison with conventional treatment (i.e. no surgery) or OSR for two populations: JRAAAs and TAAAs. The systematic evidence review was funded by the National Institute for Health Research Health Technology Assessment Programme. Resources were searched from inception to October 2013, including MEDLINE (OvidSP), EMBASE (OvidSP) and the Cochrane Central Register of Controlled Trials (Wiley) and, additionally, for cost-effectiveness, NHS Economic Evaluation Database (NHS EED; Wiley) and EconLit (EBSCOhost). Conference abstracts were also searched. Studies were included based on an intervention of either fEVAR or bEVAR and a comparator of either OSR or no surgery. For clinical effectiveness, observational studies were excluded only if they were not comparative, i.e. explicitly selected on the basis of prognosis. For clinical effectiveness, searches retrieved 5253 records before deduplication. Owing to overlap between the databases, 1985 duplicate records were removed. Of the remaining 3268 records, based on titles and abstracts, 3244 records were excluded, leaving 24 publications to be ordered. All 24 studies were excluded as none of them satisfied the inclusion criteria. Sixteen studies were excluded on study design, six on intervention and two on comparator. Five out of 16 studies excluded on study design reported a comparison. However, all of the studies acknowledged that they had groups that were not comparable at baseline given that they had selectively assigned younger, fitter patients to OSR. Therefore, these studies were considered 'non-comparative'. For cost-effectiveness, searches identified 104 references before deduplication. Owing to overlap between the databases, 34 duplicate records were removed. Of the remaining 70 records, seven were included for the full assessment based on initial screening. After a full-text review, no studies were included. Because of the lack of clinical effectiveness evidence and difficulty in estimating costs given the rapidly changing and variable technology, a cost-effectiveness analysis CEA) was not performed. Instead a detailed description of modelling methods was provided. The investigators concluded that, despite a thorough search, no studies could be found that met the inclusion criteria. All studies that compared either fEVAR or bEVAR with either OSR or no surgery explicitly selected patients based on prognosis, i.e. essentially the populations for each comparator were not the same. Despite not being able to conduct a CEA, the investigators have provided detailed methods for the conduct if data becomes available. The investigators recommended at least one clinical trial to provide an unbiased estimate of effect for fEVAR/bEVAR compared with OSR or no surgery. This trial should also collect data for a CEA.

O'Donnell et al (2020) compared outcomes of fenestrated (FEVAR) and open repairs of complex abdominal aortic aneurysms (cAAA). The investigators noted that FEVAR has emerged as an alternative to open surgery for treating cAAA, but direct comparisons are limited. The investigators studied all repairs of intact or symptomatic cAAA in the Vascular Quality Initiative between 2012 and 2018, excluding chimney/snorkels and any devices implanted under Investigational Device Exemption studies. The investigators compared open repairs, commercially available FEVAR devices and physician-modified endografts (PMEG) using inverse probability weighting. As a secondary analysis, the investigators compared PMEG separately. The investigators identified 3253 cAAA repairs: 2125 open (65%), 877 FEVAR (27%), and 251 PMEG (8%). Patients undergoing FEVAR were older, with larger aneurysms, and more comorbidities. Propensity-weighted perioperative mortality was similar between open repair and FEVAR (4.7% vs 3.3%, respectively, P = 0.17), but open repair was associated with higher rates of myocardial infarction (5.0% vs 3.0%, P = 0.03), acute kidney injury (25% vs 16%, P < 0.001), and new dialysis (4.3% vs 2.1%, P = 0.003). However, propensity-weighted long-term mortality was higher following FEVAR [Hazard Ratio (HR) 1.7 (1.1-2.6), P = 0.02]. Although outcomes of commercially available FEVAR and PMEG were similar, there was a trend toward higher long-term mortality with PMEG compared to FEVAR [HR 1.7 (0.9-3.1), P = 0.09). The investigators concluded that, in patients undergoing cAAA repair, open surgery was associated with higher overall survival than FEVAR and similar perioperative mortality, but longer lengths of stay, and higher rates of postoperative renal dysfunction and MI. PMEG were associated with similar perioperative results as commercially available FEVAR, but further study is needed to establish their long-term durability.

Li et al (2016) noted that juxtarenal aortic aneurysms (JAA) account for approximately 15% of abdominal aortic aneurysms. Fenestrated endovascular aneurysm repair (FEVAR) and chimney endovascular aneurysm repair (CH-EVAR) are both effective methods to treat JAAs, but the comparative effectiveness of these treatment modalities is unclear. The authors searched the PubMed, Medline, Embase, and Cochrane databases to identify English language articles published between January 2005 and September 2013 on management of JAA with fenestrated and chimney techniques to conduct a systematic review to compare outcomes of patients with juxtarenal aortic aneurysm (JAA) treated with the two techniques. The authors compared nine F-EVAR cohort studies including 542 JAA patients and 8 CH-EVAR cohorts with 158 JAA patients regarding techniques success rates, 30-day mortality, late mortality, endoleak events and secondary intervention rates. The authors stated that the results of this systematic review indicate that both fenestrated and chimney techniques are attractive options for JAAs treatment with encouraging early and mid-term outcomes.

Yaoguo et al (2017) reviewed data pertaining to fenestrated endograft technique and chimney stent repair of complex aortic aneurysm for comparative analysis of the outcomes. A comprehensive search of relevant databases was conducted to identify articles in English, related to the treatment of complex aortic aneurysm with fenestrated endovascular aneurysm repair and chimney stent repair, published until January 2015. A total of 42 relevant studies and 2264 patients with aortic aneurysm undergoing fenestrated endovascular aneurysm repair and chimney stent repair were included in the review. A total of 4413 vessels were involved in these processes. The cumulative 30-day mortality was 2.4% and 3.2% (p = 0.459). The follow-up aneurysm-related mortality was 1.4% and 3.2% (p = 0.018), and target organ dysfunction was 5.0% and 4.0% in fenestrated endovascular aneurysm repair and chimney stent repair, respectively ( p = 0.27). A total of 156 vessels showed restenosis or occlusion after primary intervention (3.6% and 3.4% in fenestrated endovascular aneurysm repair and chimney stent repair, respectively, p = 0.792). The cumulative type I endoleak was 2.0% (38/1884) after fenestrated endovascular aneurysm repair compared with 3.4% (13/380) after chimney stent repair ( p = 0.092), and the type II endoleak was 5.4% (102/1884) and 5.3% (20/380), respectively ( p = 0.905). Approximately, 1.1% and 1.6% increase in aneurysm was observed following fenestrated endovascular aneurysm repair and chimney stent repair, respectively ( p = 0.437). The re-intervention frequency was 205 and 19 cases after fenestrated endovascular aneurysm repair and chimney stent repair, respectively (11.7%, 5.6%, p = 0.001). The authors concluded that fenestrated endovascular aneurysm repair and chimney stent repair are safe and effective in treating patients with complex aortic aneurysm. A higher aneurysm-related mortality was observed in chimney stent repair while fenestrated endovascular aneurysm repair was associated with a higher re-intervention rate.

Rao et al (2015) observed that open repair is the gold standard management for juxtarenal aneurysms. Fenestrated endovascular aneurysm repair (FEVAR) is indicated for high-risk patients. The long-term outcomes of FEVAR are largely unknown, and there is no Level I comparative evidence. The authors conducted a systematic review and meta-analysis of case series to compare elective juxtarenal aneurysm surgery by open repair and FEVAR. A systematic literature search was conducted for all published studies on elective repair of juxtarenal aneurysms by FEVAR and open repair. The MEDLINE, EMBASE, and Cochrane databases were searched from 1947 to April 2013. The exclusion criteria were case series of <10 patients or ruptured aneurysms. The primary outcomes were perioperative mortality and postoperative renal insufficiency. The secondary outcomes were secondary reinterventions and long-term survival. The authors identified 35 case series with data on 2326 patients. Perioperative mortality was 4.1% in open repair and FEVAR case series (odds ratio for open repair with FEVAR, 1.059; 95% confidence interval, 0.642-1.747; P = .822). Postoperative renal insufficiency was not significantly different (odds ratio for open repair with FEVAR, 1.136; 95% confidence interval, 0.754-1.713; P = .542). FEVAR patients had higher rates of secondary reintervention, renal impairment during follow-up, and a lower long-term survival compared with open repair patients. The authors concluded that FEVAR and open repair have similar short-term outcomes but have diverging long-term outcomes that may be secondary to the selection bias of FEVAR being offered to high-risk patients. FEVAR is a favorable option in high-risk patients, and open repair remains viable as the gold standard.

Ou et al (2015) said that fenestrated endovascular repair is an alternative to open repair in the management of juxtarenal aortic aneurysms and short-neck abdominal aortic aneurysms (AAAs). The investigators sought to examine the evidence in published literature on the use of fenestrated endovascular stent grafts in the treatment of juxtarenal and short-neck AAAs. A systematic review was formulated under the instruction of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Articles published from January 1996 to October 2014 in English language were included. Published studies on fenestrated endovascular stent grafts in treating juxtarenal and short-neck AAAs were systematically searched and reviewed through a computerized search of PubMed and Ovid MEDLINE and cross-referenced. Title key words include "fenestrated", "juxtarenal", and "short neck". All relevant published articles up to first October 2014 were reviewed. A total of 529 nonduplicated publications were identified but only 15 articles were eligible for our qualitative analysis, with 763 patients and 2,040 target vessels. Twelve studies were included in cohort studies with a short or medium follow-up period (median range, 6-67 months). The mean 30-day and late follow-up mortality were 1.7% (range, 0-4%) and 20.1% (range, 4-50%), respectively, with 5.3% aneurysm-related late deaths. A total of 74 target vessels (3.6%) were lost in all the studies with 65 of them (87.8%) lost postoperatively. Overall, 28.8% patients endured renal dysfunction postoperatively, whereas 2.5% of patients required dialysis. Target vessel events and endoleaks were the 2 major indications for reintervention, accounting for 63.8%. Fourteen aneurysm sacs (1.8%) were enlarged continuously during follow-up and a half were due to type II endoleaks. Migration of the proximal fenestration component was reported with 3.0%. One registry study reported 4.1% of early mortality, higher than any cohort studies, whereas the target vessel loss was relatively low (1.6%). Freedom of late secondary intervention decreased from 90% at year 1 to 70% at year 3. Two nonrandom controlled comparative studies showed no definitive superiority of fenestrated repair over the open surgery. The authors concluded that contemporary published literature does not produce a high enough level of evidence that leads to a change in treatment guidelines for juxtarenal or short-neck aneurysm. Fenestrated endovascular repair is a safe and efficacious treatment, particularly for those deemed surgically high risk. Growing experience and innovation of stent graft are essential for the advancement of fenestrated grafting.

Kamman et al (2015) stated that the optimal management strategy for chronic type B aortic dissections (CBAD) is unknown. Therefore, the authors systematically reviewed the literature to compare results of open surgical repair (OSR), standard thoracic endovascular aortic repair (TEVAR) or branched and fenestrated TEVAR (BEVAR/FEVAR) for CBAD. EMBASE and MEDLINE databases were searched for eligible studies between January 2000 and October 2015. Studies describing outcomes of OSR, TEVAR, B/FEVAR, or all, for CBAD patients initially treated with medical therapy, were included. Primary endpoints were early mortality, and one-year and five-year survival. Secondary endpoints included occurrence of complications. Furthermore, a Time until Treatment Equipoise (TUTE) graph was constructed. Thirty-five articles were selected for systematic review. A total of 1081 OSR patients, 1397 TEVAR patients and 61 B/FEVAR patients were identified. Early mortality ranged from 5.6% to 21.0% for OSR, 0.0% to 13.7% for TEVAR, and 0.0% to 9.7% for B/FEVAR. For OSR, one-year and five-year survival ranged 72.0%-92.0% and 53.0%-86.7%, respectively. For TEVAR, one-year survival was 82.9%-100.0% and five-year survival 70.0%-88.9%. For B/FEVAR only one-year survival was available, ranging between 76.4% and 100.0%. Most common postoperative complications included stroke (OSR 0.0%-13.3%, TEVAR 0.0%-11.8%), spinal cord ischemia (OSR 0.0%-16.4%, TEVAR 0.0%-12.5%, B/FEVAR 0.0%-12.9%) and acute renal failure (OSR 0.0%-33.3%, TEVAR 0.0%-34.4%, B/FEVAR 0.0%-3.2%). Most common long-term complications after OSR included aneurysm formation (5.8%-20.0%) and new type A dissection (1.7-2.2%). Early complications after TEVAR included retrograde dissection (0.0%-7.1%), malperfusion (1.3%-9.4%), cardiac complications (0.0%-5.9%) and rupture (0.5%-5.0%). Most common long-term complications after TEVAR were rupture (0.5%-7.1%), endoleaks (0.0%-15.8%) and cardiac complications (5.9%-7.1%). No short-term aortic rupture or malperfusion was observed after B/FEVAR. Long-term complications included malperfusion (6.5%) and endoleaks (0.0%-66.7%). Reintervention rates after OSR, TEVAR and B/FEVAR were 5.8%-29.0%, 4.3%-47.4% and 0.0%-53.3%, respectively. TUTE for OSR was 2.7 years, for TEVAR 9.9 months and for B/FEVAR 10.3 months. The authors statted that they found a limited early survival benefit of standard TEVAR over OSR for CBAD. Complication rates after TEVAR are higher, but complications after OSR are usually more serious. Initial experiences with B/FEVAR show its feasibility, but long-term results are needed to compare it to OSR and standard TEVAR. The authors concluded that optimal treatment of CBAD remains debatable and merits a patient specific decision. TUTE seems a feasible and useful tool to better understand management outcomes of CBAD.

An international assessment by Health Technology Scotland (2018) found higher perioperative morbidity with open surgical repair, but higher reintervention rates with fenestrated\branched grafts compared to open surgical repair.  Most data are from retrospective case series, with only one prospective comparative study identified. They also noted the paucity of long-term data for the fenestrated grafts.  Based upon the single prospective comparative study, there were no significant differences in 30-day mortality in a prospective study comparing open surgery to fenestrated/branched stent grafts. 

An international evidence review by NICE (2018) found, based on "low quality evidence," that complex endovascular repair of aortic aneurysms was associated with a shorter hospital stay than open surgical repair, and that, based upon "very low quality evidence," they could not differentiate differences in 30-day mortality between complex EVAR and open surgical repair, and could not differentiate between rates of hemodialysis, pneumonia, stroke and reintervention rates between patients treated by complex EVAR and those treated by open repair. These conclusions were based upon the only prospective comparative study of complex EVAR, which followed 90 patients for a mean follow-up of 15.2 months. The assessment also found, based upon modeling, that endovascular repair of complex aortic aneurysms to be dominated by no intervention, meaning that complex EVAR resulted in higher costs and fewer QALYs than no intervention. The report concluded: "The committee noted that the evidence comparing complex EVAR with open surgical repair was extremely limited in quantity and quality. No RCTs were identified and the single non-randomised comparative study that met this review’s inclusion criteria was small in size and only assessed mortality rates at 30-day follow-up. The results of the study, coupled with results from a new health economic model developed for this population (discussed below), led the committee to conclude that there was no evidence that complex EVAR yields a net advantage over open surgery. However, the committee were mindful that longer-term evidence from large RCTs could clarify the clinical utility of complex EVAR, and inform future health economic modelling. Thus, they recommended that the procedure should not be performed outside the confines of an RCT."

Bifurcated-Bifurcated Aneurysm Repair of Aorto-Iliac Aneurysms

Shin and Starnes (2017) noted that up to 40 % of AAAs have co-existent iliac artery aneurysms (IAAs).  In the past, successful endovascular repair required internal iliac artery (IIA) embolization, which can lead to pelvic or buttock ischemia.  These investigators described a technique that uses a readily available solution with a minimally altered off-the-shelf bifurcated graft in the IAA to maintain IIA perfusion.  From August 2009 to May 2015, a total of 14 patients with AAAs and co-existing IAAs underwent repair with a bifurcated-bifurcated approach.  A 22-mm or 24-mm bifurcated main body device was used in the IAA with extension of the "contralateral" limb into the IIA.  Intra-operative details including operative time, fluoroscopy time, and contrast agent use were recorded.  Outcome measures assessed were operative technical success and a composite outcome measure of IIA patency, freedom from re-intervention, and clinically significant endoleak at 1 year.  Technical success was achieved in 93 % of patients, with successful treatment of the AAA and IAA and preservation of flow to at least 1 IIA.  The procedure was performed with a completely percutaneous bilateral femoral approach in 92 % of patients; 3 patients had a type II endoleak on initial follow-up imaging, but none was clinically significant.  There were no cases of bowel ischemia or erectile dysfunction; 1 patient had buttock claudication ipsilateral to IIA coil embolization (contralateral to bifurcated iliac repair and preserved IIA) that resolved by 6-month follow-up; 2 patients required re-interventions; 1 patient presented to his first follow-up visit on post-operative day 25 with thrombosis of the right external iliac limb ipsilateral to the bifurcated iliac repair, which was successfully treated with thrombectomy and stenting of the limb.  This same patient presented at 83 months with growth of the preserved IIA to 3.9 cm and underwent coil embolization of the aneurysm.  Another patient presented for surveillance 44 months after his original repair with component separation of the mating stent and the iliac bifurcated stent grafts.  This was treated with a limb extension and endo-anchors to fuse the endografts.  Of the 13 patients who underwent bifurcated-bifurcated repair, 100 % of the preserved IIAs remained patent at last follow-up.  The composite outcome measure of IIA patency and freedom from re-intervention and clinically significant endoleak at 1 year was 92 % (n = 12/13).  The authors concluded that in this small retrospective review, bifurcated-bifurcated aneurysm repair of aorto-iliac aneurysms with preservation of perfusion to the IIA was technically feasible and safe with good short-term and mid-term results in male patients.  These preliminary findings need to be validated by well-designed studies.

Endovascular Aneurysm Sealing (e.g., the Nellix Device) for the Treatment of Abdominal Aortic Aneurysms

Bockler and associates (2015) noted that despite improvements in endograft devices, operator technique, and patient selection, endovascular repair has not achieved the long-term durability of open surgical aneurysm repair. Persistent or recurrent aneurysm sac flow from failed proximal sealing, component failure, or branch vessel flow underpins a significant rate of re-intervention after endovascular repair. The Nellix device (Endologix, Irvine, CA) employs a unique design with deployment of polymer-filled EndoBags surrounding the endograft flow lumens, sealing the aneurysm sac space and potentially reducing complications from persistent sac flow.  

Bockler et al (2015) reported on a retrospective analysis represented the initial experience in consecutive patients treated with the device in real-world practice.  This study was performed at 6 clinical centers in Europe and 1 in New Zealand during the initial period after commercialization of the Nellix device.  Patients underwent evaluation with CT and other imaging modalities following local standards of care.  Patients were selected for treatment with Nellix and treated by each institution according to its endovascular repair protocol.  Clinical and imaging end-points included technical success (successful device deployment and absence of any endoleak at completion angiography), freedom from all-cause and aneurysm-related mortality, endoleak by type, limb occlusion, aneurysm rupture, and re-intervention.  During a 17-month period, a total of 171 patients with AAAs were treated with the Nellix device and observed for a median of 5 months (range of 0 to 14 months).  The 153 men and 18 women with mean age of 74 ± 7 years had aneurysms 61 ± 9 mm in diameter with an average infra-renal neck length of 28 ± 15 mm and infra-renal angulation of 37 ± 22 degrees.  Technical success was achieved in all but 2 patients (99 %); 1 patient had a type Ib endoleak and another had a type II endoleak.  Through the last available follow-up, type Ia endoleak was observed in 5 patients (3 %), type Ib endoleak in 4 patients (2 %), and type II endoleak in 4 patients (2 %).  There were 8 limb occlusions (5 %), among which 7 were evident at the 1-month follow-up visit.  Aneurysm-related re-interventions were performed in 15 patients (9 %).  There were no aneurysm ruptures or open surgical conversions.  The authors concluded that this first multi-center post-market report of the Nellix device for infra-renal AAA repair demonstrated satisfactory results during the initial learning phase of this new technology.  The rate of aneurysm exclusion was high, and frequency of complications was low.  They stated that more definitive conclusions on the value of this novel device await the results of the ongoing Nellix EVAS FORWARD Global Registry and the EVAS FORWARD investigational device exemption trial.

Carpenter and co-workers (2017) stated that the Nellix EndoVascular Aneurysm Sealing (EVAS) System (Endologix, Inc., Irvine, CA) is a novel approach to AAA treatment whereby polymer is used to fill the AAA sac.  These researchers reported 1-year results of the IDE pivotal trial.  Eligible patients were treated at 30 sites in the U.S. and Europe.  Inclusion criteria required an asymptomatic infra-renal AAA, with a neck length of greater than or equal to 10 mm and less than or equal to 60° angle, iliac artery blood lumen diameter of 9 to 35 mm, access artery diameter of greater than or equal to 6 mm, and serum creatinine of less than or equal to 2 mg/dL.  Follow-up included CT angiography scans at 30 days, 6 months, and 1 year that were evaluated by a core laboratory.  The primary safety end-point was 30-day major adverse events (MAEs), which were compared with a performance goal of less than 56 % (the Society for Vascular Surgery open repair control group rate).  The primary effectiveness end-point was treatment success at 1 year, which was compared with a performance goal of greater than 80 %.  Treatment success required procedural technical success and absence of AAA rupture during follow-up, conversion to open surgical repair, endoleak (type I or III) at 1 year, migration of greater than 10 mm causing complications or requiring secondary intervention, aneurysm enlargement, or secondary procedures through 1 year for resolution of endoleak, device obstruction or occlusion, or device defect.  Of 150 treated patients, 149 (99.3 %) completed 1-year follow-up.  The MAEs rate at 30 days was 2.7 % (95 % CI: 0.7 % to 6.7 %), satisfying the primary safety end-point (less than 56 %).  The 1-year treatment success was 94 % (95 % CI: 88.6 % to 97.4 %), achieving the primary effectiveness end-point (greater than 80 %).  At 1 year, key secondary outcomes included 6.7 % MAEs, 4.7 % serious device-related events, 1.3 % AAA-related mortality, 3.7 % secondary interventions, and 0.7 % surgical conversions; MAEs through 1 year included death (n = 6), stroke (n = 3), bowel ischemia (n = 2), renal failure (n = 2), respiratory failure (n = 2), and myocardial infarction (n =1).  One iatrogenic AAA rupture occurred and 1 AAA rupture was reported during follow-up. AAA sac enlargement (greater than 5 mm) was 1.5 % at 1 year.  Endoleaks were present in 4 patients (3.1 %) at 1 year (1 type Ib and 3 type II).  Migration of greater than 10 mm occurred in 3 patients (2.3 %), but none required secondary intervention.  The authors concluded that outcomes with this novel endovascular therapy for AAA, the Nellix EVAS System, were encouraging.  The primary safety and effectiveness end-points have been met.  Moreover, they noted that low morbidity, low mortality, and high procedural and treatment success were achieved despite the inevitability of a learning curve and unique risks associated with a new device and technique; long-term follow-up is in progress.

Youssef and associates (2017) examined the technical success and clinical outcome of re-interventions using the Nellix EVAS System to treat complications after EVAR.  A total of 15 consecutive patients (mean age of 79 years; 14 men) with prior EVAR were treated with EVAS between March 2014 and December 2015 at 2 institutions.  The failed prior EVARs included 13 bifurcated endografts, 1 bifurcated graft plus fenestrated cuff, and 1 tube endograft.  Endoleaks were the predominant indications: type Ia in 10 and type III in 5 (3 type IIIa and 2 type IIIb).  All patients presented with progressive aortic aneurysms (median of 7.85-cm diameter; range of 6.5 to 11); 8 patients were treated on an urgent or emergency basis (6 symptomatic aneurysms and 2 contained ruptures).  All patients underwent Nellix relining of the failed stent-graft; 10 had chimney (Ch) procedures in combination with EVAS (chEVAS) because the proximal landing zones were inadequate.  Technical success was 100 %.  All endoleaks were successfully sealed, and no additional intervention was needed.  No further endoleak after EVAS or chEVAS was recorded.  Endobag protrusion occurred in 1 case without sequelae.  One elderly patient with ruptured aneurysm died from multiple organ failure 2 months post-operatively.  One renal artery guide-wire injury led to nephrectomy because of active bleeding.  No re-interventions, aneurysm-related mortalities, graft thrombosis, endoleaks, or chimney graft occlusions were observed during a median follow-up of 8 months (range of 3 to 24).  The authors concluded that the present preliminary experience demonstrated that the use of EVAS/chEVAS was feasible for treatment of failed EVAR.  Moreover, they stated that this technique may be used as bailout or an alternative treatment when other established methods are infeasible or not available.

Unlu and colleagues (2017) stated that despite improvements in endograft design, operator skills, and patient selection, late EVAR associated complications and need for re-interventions remains the Achilles heel.  These complications erode the early benefit over open aneurysm repair during long-term follow-up.  The recently introduced endovascular aneurysm sealing (EVAS) is an innovative technology with the intention to lower these EVAR related complications.  These investigators reviewed the EVAS technique, indications, and possible applications, and provided a critical appraisal of clinical outcomes.  The authors concluded that  EVAS is a promising technique for treating AAAs, and early efficacy data were encouraging in very suitable straight forward anatomy.  Moreover, they stated that the Nellix device is still in development; long-term results are needed.

Brown and co-workers (2017) noted that there has been a clear move towards endovascular repair of AAAs owing to better peri-operative outcomes compared with open surgical repair. However, follow-up has continued to reveal relatively high rates of endoleaks and re-interventions.  Improvements in endovascular stent-grafts aim to decrease these complications.  In a systematic review, these investigators determined the early outcomes of AAA sealing.  Standard PRISMA guidelines were followed.  They performed a literature search extract any publication related to the endovascular aneurysm sealing device.  The total number of patients in this systematic review of 11 studies was 684, with a mean age of 73.2 years, and 587 (88.0 %) were men.  The majority were undergoing elective procedures (n = 606, 91.0 %), the remainder as emergencies (n = 30, 4.5 % as ruptures; n = 30, 4.5 % as symptomatic).  Technical success rate including emergency cases was 99.1 %; 30-day mortality rate was 2.6 % (n = 17) including all cases, and 1.0 % (n = 6) including elective cases only; 30-day endoleak detection rate was 4.7 % (n = 31) including all cases, and 4.8 % (n = 29) including elective cases only; 30-day aneurysm-related re-intervention rate was 5.7 % (n = 38) including all cases, and 4.6 % (n = 28) including elective cases only. There was no conversion to open surgery within 30 days post-op in the elective cases.  There were 3 delayed conversions to open surgery within 30 days and 1 report of stent migration causing rupture in the emergency setting.  The authors concluded that this novel endovascular aneurysm-sealing device for AAA repair has shown respectable early outcomes.  Good technical success rates, in both elective and emergency settings, low rates of all-type endoleaks and low re-intervention rates have all been demonstrated.  They stated that endovascular aneurysm sealing is proving to be a safe alternative to open and endovascular aneurysm repair; however, longer term follow-up results are needed to evaluate the safety and effectiveness of the device in the long-term.

Cerebrospinal Fluid Drainage During Endovascular Aortic Aneurysm Repair

Suarez-Pierre and associates (2019) noted that spinal cord ischemia is among the most devastating complications of thoracic endovascular aortic repair (TEVAR).  Spinal fluid drainage has been proposed as a viable means to reduce spinal cord ischemia, but few data exist to support its routine use.  These investigators examined the association of pre-operative spinal fluid drainage with the risk of spinal cord ischemia following TEVAR.  The Vascular Quality Initiative (VQI) TEVAR module was queried for adult patients (greater than or equal to 18 years) undergoing TEVAR (coverage of zones 0 to 5) between September 2014 and March 2018 (inclusive).  Patients with pre-operative spinal mal-perfusion, aortic rupture on presentation, and connective tissue disorders were excluded.  One-to-one propensity matching was used to balance patients on 44 separate dimensions by the nearest neighbor principle to compare those with vs those without pre-operative spinal drainage.  The primary end-point was spinal cord ischemia still present at the time of discharge; secondary outcomes were 30-day mortality and prolonged intensive care unit (ICU) stay (greater than 7 days).  Among 4,287 patients who underwent TEVAR (mean age of 67.1 [standard deviation [SD], 13.7] years; 1,665 [38.8 %] women and 2,622 [61.2 %] men), 2,076 had a spinal drain placed.  Propensity matching yielded 1,292 pairs with adequate co-variate balance (all 44 absolute standardized differences of less than 0.1).  In the 2,584 propensity-matched patients, spinal drain placement was associated with a reduced risk of spinal cord ischemia (1.5 % versus 2. 5%; risk-adjusted OR, 0.47; 95 % CI: 0.24 to 0.89; p = 0.02).  The rates of 30-day mortality (4.5 % versus 5.0 %; risk-adjusted OR, 0.67; 95 % CI: 0.44 to 1.01; p = 0.05) and prolonged ICU stay (7.0 % versus 5.7 %; risk-adjusted OR, 1.10; 95 % CI: 0.84 to 1.45; p = 0.48) did not differ on the basis of spinal drain placement.  The cross-over rate was 10 % (127/1,292), and those with post-operative drain placement had a 20 % (26/127) spinal cord ischemia rate on discharge.  The authors concluded that among patients undergoing thoracic and thoraco-abdominal endovascular aortic repair, pre-operative placement of a spinal drain, compared with no drain, was associated with reduced risk of spinal cord ischemia.  These researchers stated that cerebrospinal fluid drainage (CSFD) as a rescue measure does not provide the same protection offered by routine pre-operative placement.  They stated that further investigation, including RCTs, is needed to more definitively determine the role for spinal drainage in TEVAR.

The author stated that this study was subject to unexpected confounders because of its observational design; despite extensive risk adjustment, these findings may be considered only associative in nature.  Large multi-institutional data sets are subject to variability in data entry and mis-coding; however, the end-points examined in this study were concise and interpreted universally across practices.  Participation in the VQI registry was voluntary; however, centers that did participate were required to submit 100 % of their cases to avoid selection bias.  In the multi-variable model, left subclavian artery re-vascularization did not demonstrate an association with decreased rate of spinal cord ischemia; this may be a reflection of the substantial proportion of patients (approximately 30 %) who had missing values.  Avoidance of hypotension, intra-operative neuromonitoring for signs of spinal cord ischemia, peri-operative hypothermia, technique of drain placement, pressure thresholds for CSF evacuation, and duration of use were not standardized in this multi-institutional study.  Complications specific to pre-operative CSFD were not examined.

Malloy and colleagues (2020) noted that spinal cord injury (SCI) is a known complication of aortic aneurysm repair.  Previous reports indicated that CSFD may reduce incidence of SCI during open aortic aneurysm repair but its utility in endovascular repair remains poorly understood.  In a systematic review, these investigators examined the protocols and outcomes of CSFD in patients undergoing endovascular aortic aneurysm repair.  The PRISMA guidelines were employed to carry out a systematic literature review.  PubMed, Scopus, Ovid, Cochrane, and Embase were searched for articles published since 2016 using search terms "(cerebrospinal fluid diversion OR CSF diversion OR lumbar drain OR subarachnoid drain OR spinal) AND (aortic aneurysm AND thoracic AND endovascular OR TEVAR)".  A total of 92 articles were identified and screened by 2 independent reviewers, and 23 studies met criteria for full-text review after initial screening.  A total of 8 studies met full inclusion criteria for final analysis; 6 studies reported incidence of SCI in patients with CSFD and 2 compared SCI incidence between patients with and without CSFD.  Protocols for drainage most commonly included draining to a target pressure intra- and post-operatively, between 8 and 12 mm Hg.  Incidence of SCI ranged from 0 % to 17 % in patients with CSFD, and from 0 % to 50 % in those without CSFD.  Rates of CSFD-related complications ranged from less than 1 % to 28 %.  The authors concluded that there may be a protective benefit of CSFD in preventing SCI, but there remains significant variation in drain placement protocols; and significant potential bias exists in the reviewed data.  These researchers stated that higher quality studies on the role of CSFD in endovascular aortic aneurysm repair are needed.

Karkkainen and co-workers (2020) examined the rates and risk factors of complications related to CSFD during first stage and completion fenestrated-branched endovascular aortic repair (F-BEVAR) of para-renal and thoraco-abdominal aortic aneurysms.  These investigators reviewed the outcomes of 293 consecutive patients enrolled in a prospective, non-randomized study to examine outcomes of F-BEVAR between 2013 and 2018.  Patients who received CSFD during first-stage thoracic endovascular aortic repair, index F-BEVAR, or completion of temporary aneurysm sac perfusion procedures were included in the analysis.  CSFD complications were graded as severe or moderate if they were life-threatening, escalated the level of care, or prolonged the hospital stay.  Presence of substantial degenerative lumbar disease (DLD) was identified based on review of pre-operative CT.  End-points included technical difficulties during CSFD placement and CSFD-related complications.  A total of 187 patients (mean age of 73 ± 8 years; 70 % men) treated for 20 para-renal and 167 thoraco-abdominal aortic aneurysms received CSFD in 240 procedures, including 51 first-stage thoracic endovascular aortic repairs, 184 index F-BEVARs, and 5 completion temporary aneurysm sac perfusion procedures; 19 patients (10 %) had 22 CSFD-related complications after 21 aortic procedures (9 %).  Complications were graded as severe-to-moderate in 17 patients (9 %).  There were 12 patients (6 %) with intra-cranial hypotension, including 3 (2 %) who had intra-cranial hemorrhage and 9 (5 %) with post-dural puncture headache requiring blood patches in 6.  Another 6 patients (3 %) developed spinal hematomas resulting in paraplegia in 2 (1 %) and transient paraparesis in 2 (1 %); 1 patient had CSF leakage from the puncture site (no intervention required); 4 patients had bleeding during attempted drain placement, which required postponement of F-BEVAR.  Technical difficulties were observed in 57 drain insertions (24 %), more often in patients with DLD than in those without DLD (35/113 [31 %] versus 22/121 [18 %]; p = 0.03).  Fluoroscopic guidance was used in 44 drain placements (18 %) with a lower rate of technical difficulties compared with the blind approach (9 % versus 28 %; p = 0.01).  There was a statistically non-significant trend toward more complications in patients with technical challenges (14 % versus 7 %; p = 0.10).  Of 13 study patients who developed SCI during aortic procedures, 4 (31 %) were attributed to CSFD.  The authors concluded that although CSFD was widely used to prevent ischemic SCI during complex aortic repair, the risk of major CSFD-related complications is not negligible and should be carefully weighed against its potential benefits; 1/3 of SCIs were caused by CSF drain placement.  The use of fluoroscopic guidance may decrease the risk of CSFD-related complications.

The authors stated that the main drawback of this study was the retrospective nature of collecting CSFD-related data.  Although the note template for spinal drain insertion procedure was fairly well-structured in the authors’ electronic medical record, there was a possibility of variation in reporting between neuroradiologist and anesthesiologist because these specialists used different note templates.  The association between CSFD and intra-cranial hemorrhage was often obscure, and causality could be difficult to establish; these investigators agreed on the etiology of 2 intra-cranial hemorrhage and 1 remained inconclusive; CT scans were often reported in a standardized fashion by the radiologists; however, DLD was not well-defined in this retrospective study because it mostly relied on the radiology report, and it was very common in middle-aged to older individuals.   Furthermore, the numbers of end-point events were too small to perform meaningful multi-variable analyses.

Table: CPT Codes / HCPCS Codes / ICD-10 Codes

Code	Code Description
Information in the [brackets] below has been added for clarification purposes.   Codes requiring a 7th character are represented by "+":
CPT codes covered if selection criteria are met:
33880	Endovascular repair of descending thoracic aorta (e.g., aneurysm, pseudoaneurysm, dissection, penetrating ulcer, intramural hematoma, or traumatic disruption); involving coverage of left subclavian artery origin, initial endoprosthesis plus descending thoracic aortic extension(s), if required, to the level of celiac artery origin
33881	not involving coverage of left subclavian artery origin, initial endoprosthesis plus descending thoracic aortic extension(s), if required, to level of celiac artery origin
33883	Placement of proximal extension prosthesis for endovascular repair of descending thoracic aorta (e.g., aneurysm, pseudoaneurysm, dissection, penetrating ulcer, intramural hematoma, or traumatic disruption); initial extension
+ 33884	each additional proximal extension (List separately in addition to code for primary procedure)
33886	Placement of distal extension prosthesis(s) delayed after endovascular repair of descending thoracic aorta
33889	Open subclavian to carotid artery transposition performed in conjunction with endovascular repair of descending thoracic aorta, by neck incision, unilateral
33891	Bypass graft, with other than vein, transcervical retropharyngeal carotid-carotid, performed in conjunction with endovascular repair of descending thoracic aorta, by neck incision
34701 - 34702	Endovascular repair of infrarenal aorta by deployment of an aorto-aortic tube endograft including pre-procedure sizing and device selection, all nonselective catheterization(s), all associated radiological supervision and interpretation, all endograft extension(s) placed in the aorta from the level of the renal arteries to the aortic bifurcation, and all angioplasty/stenting performed from the level of the renal arteries to the aortic bifurcation
34703 - 34706	Endovascular repair of infrarenal aorta and/or iliac artery(ies) by deployment of an aorto-bi-iliac endograft including pre-procedure sizing and device selection, all nonselective catheterization(s), all associated radiological supervision and interpretation, all endograft extension(s) placed in the aorta from the level of the renal arteries to the iliac bifurcation, and all angioplasty/stenting performed from the level of the renal arteries to the iliac bifurcation
34707 - 34708	Endovascular repair of iliac artery by deployment of an ilio-iliac tube endograft including pre-procedure sizing and device selection, all nonselective catheterization(s), all associated radiological supervision and interpretation, and all endograft extension(s) proximally to the aortic bifurcation and distally to the iliac bifurcation, and treatment zone angioplasty/stenting, when performed, unilateral
34709	Placement of extension prosthesis(es) distal to the common iliac artery(ies) or proximal to the renal artery(ies) for endovascular repair of infrarenal abdominal aortic or iliac aneurysm, false aneurysm, dissection, penetrating ulcer, including pre-procedure sizing and device selection, all nonselective catheterization(s), all associated radiological supervision and interpretation, and treatment zone angioplasty/stenting, when performed, per vessel treated (List separately in addition to code for primary procedure)
34710 - 34711	Delayed placement of distal or proximal extension prosthesis for endovascular repair of infrarenal abdominal aortic or iliac aneurysm, false aneurysm, dissection, endoleak, or endograft migration, including pre-procedure sizing and device selection, all nonselective catheterization(s), all associated radiological supervision and interpretation, and treatment zone angioplasty/stenting, when performed
34712	Transcatheter delivery of enhanced fixation device(s) to the endograft (eg, anchor, screw, tack) and all associated radiological supervision and interpretation
34713	Percutaneous access and closure of femoral artery for delivery of endograft through a large sheath (12 French or larger), including ultrasound guidance, when performed, unilateral (List separately in addition to code for primary procedure)
+34717	Endovascular repair of iliac artery at the time of aorto-iliac artery endograft placement by deployment of an iliac branched endograft including pre-procedure sizing and device selection, all ipsilateral selective iliac artery catheterization(s), all associated radiological supervision and interpretation, and all endograft extension(s) proximally to the aortic bifurcation and distally in the internal iliac, external iliac, and common femoral artery(ies), and treatment zone angioplasty/stenting, when performed, for rupture or other than rupture (eg, for aneurysm, pseudoaneurysm, dissection, arteriovenous malformation, penetrating ulcer, traumatic disruption), unilateral (List separately in addition to code for primary procedure)
34718	Endovascular repair of iliac artery, not associated with placement of an aorto-iliac artery endograft at the same session, by deployment of an iliac branched endograft, including pre-procedure sizing and device selection, all ipsilateral selective iliac artery catheterization(s), all associated radiological supervision and interpretation, and all endograft extension(s) proximally to the aortic bifurcation and distally in the internal iliac, external iliac, and common femoral artery(ies), and treatment zone angioplasty/stenting, when performed, for other than rupture (eg, for aneurysm, pseudoaneurysm, dissection, arteriovenous malformation, penetrating ulcer), unilateral
+ 34808	Endovascular placement of iliac artery occlusion device (List separately in addition to code for primary procedure)
34812	Open femoral artery exposure for delivery of endovascular prosthesis, by groin incision, unilateral
+ 34813	Placement of femoral-femoral prosthetic graft during endovascular aortic aneurysm repair (List separately in addition to code for primary procedure)
34820	Open iliac exposure for delivery of endovascular prosthesis or iliac occlusion during endovascular therapy, by abdominal or retroperitoneal incision, unilateral
34839	Physician planning of a patient-specific fenestrated visceral aortic endograft requiring a minimum of 90 minutes of physician time
34841 - 34844	Endovascular repair of visceral aorta and infrarenal abdominal aorta (eg, aneurysm, pseudoaneurysm, dissection, penetrating ulcer, intramural hematoma, or traumatic disruption) with a fenestrated visceral aortic endograft and concomitant unibody or modular infrarenal aortic endograft and all associated radiological supervision and interpretation, including target zone angioplasty, when performed
34845 - 34848	Endovascular repair of visceral aorta and infrarenal abdominal aorta (eg, aneurysm, pseudoaneurysm, dissection, penetrating ulcer, intramural hematoma, or traumatic disruption) with a fenestrated visceral aortic endograft and concomitant unibody or modular infrarenal aortic endograft and all associated radiological supervision and interpretation, including target zone angioplasty, when performed
71260	Computed tomography, thorax; with contrast material(s)
71275	Computed tomographic angiography, chest (noncoronary), with contrast material(s), including noncontrast images, if performed, and image postprocessing
74174	Computed tomographic angiography, abdomen and pelvis, with contrast material(s), including noncontrast images, if performed, and image postprocessing
74177	Computed tomography, abdomen and pelvis; with contrast material(s)
75956	Endovascular repair of descending thoracic aorta (e.g., aneurysm, pseudoaneurysm, dissection, penetrating ulcer, intramural hematoma, or traumatic disruption); involving coverage of left subclavian artery origin, initial endoprosthesis plus descending thoracic aortic extension(s), if required, to level of celiac artery origin, radiological supervision and interpretation
75957	not involving coverage of left subclavian artery origin, initial endoprosthesis plus descending thoracic extension(s), if required, to level of celiac artery origin, radiological supervision and interpretation
75958	Placement of proximal extension prosthesis for endovascular repair of descending thoracic aorta (eg, aneurysm, pseudoaneurysm, dissection, penetrating ulcer, intramural hematoma, or traumatic disruption), radiological supervision and interpretation
75959	Placement of distal extension prosthesis (delayed) after endovascular repair of descending thoracic aorta, as needed, to level of celiac origin, radiological supervision and interpretation
CPT codes not covered for indications listed in the CPB:
Bifurcated-bifurcated aneurysm repair,Endovascular aneurysm sealing system (Nellix device) - no specific code:
37242	Vascular embolization or occlusion, inclusive of all radiological supervision and interpretation, intraprocedural roadmapping, and imaging guidance necessary to complete the intervention; arterial, other than hemorrhage or tumor (eg, congenital or acquired arterial malformations, arteriovenous malformations, arteriovenous fistulas, aneurysms, pseudoaneurysms) [for embolization of the inferior mesenteric artery]
Other CPT codes related to the CPB:
33858 - 33877	Thoracic aortic aneurysm procedures
34830 - 34834	Open repair of infrarenal aortic aneurysm or dissection
HCPCS codes not covered for indications listed in the CPB:
M0301	Fabric wrapping of abdominal aneurysm
ICD-10 codes covered if selection criteria are met:
A52.01	Syphilitic aneurysm of aorta
I71.01 - I71.6	Aortic aneurysm and dissection
I72.3	Aneurysm of iliac artery
ICD-10 codes not covered for indications listed in the CPB:
T82.330A - T82.330S	Leakage of aortic (bifurcation) graft (replacement) [not covered for preoperative embolization of inferior mesenteric artery to reduce Type II endoleak]

The above policy is based on the following references: