Fenestrated Endovascular Aneurysm Repair versus Snorkel Endovascular Aneurysm Repair: Competing yet Complementary Strategies.

Juxtarenal/pararenal aortic aneurysms and type IV thoracoabdominal aneurysms pose particular technical challenges for endovascular repair as they involve the visceral segment in addition to insufficient infrarenal neck for the use of standard endovascular aneurysm repair (EVAR) devices. To overcome these challenges, complex EVAR techniques have been developed to extend the proximal landing zone cephalad with maintaining perfusion to vital aortic branches, thereby broadening the applicability of endografting from the infrarenal to the suprarenal aorta. Complex EVAR can be divided into two broad categories: fenestrated endovascular aneurysm repair (FEVAR) and snorkel EVAR. FEVAR is a valid procedure with the standardized procedure, although it remains as a relatively complex procedure with a learning curve. Given time constraints for the custom fenestrated graft, snorkel EVAR may be an alternative for complex repairs in symptomatic or ruptured patients for whom custom-made endografts may not be immediately available. This article discusses these two most commonly used complex EVAR strategies

Elective Open Suprarenal Aneurysm Repair in England from 2000 to 2010 an Observational Study of Hospital Episode Statistics

Background: Open surgery is widely used as a benchmark for the results of fenestrated endovascular repair of complex abdominal aortic aneurysms (AAA). However, the existing evidence stems from single-centre experiences, and may not be reproducible in wider practice. National outcomes provide valuable information regarding the safety of suprarenal aneurysm repair. Methods: Demographic and clinical data were extracted from English Hospital Episodes Statistics for patients undergoing elective suprarenal aneurysm repair from 1 April 2000 to 31 March 2010. Thirty-day mortality and five-year survival were analysed by logistic regression and Cox proportional hazards modeling. Results: 793 patients underwent surgery with 14% overall 30-day mortality, which did not improve over the study period. Independent predictors of 30-day mortality included age, renal disease and previous myocardial infarction. 5-year survival was independently reduced by age, renal disease, liver disease, chronic pulmonary disease, and known metastatic solid tumour. There was significant regional variation in both 30-day mortality and 5-year survival after risk-adjustment. Regional differences in outcome were eliminated in a sensitivity analysis for perioperative outcome, conducted by restricting analysis to survivors of the first 30 days after surgery. Conclusions: Elective suprarenal aneurysm repair was associated with considerable mortality and significant regional variation across England. These data provide a benchmark to assess the efficacy of complex endovascular repair of supra-renal aneurysms, though cautious interpretation is required due to the lack of information regarding aneurysm morphology. More detailed study is required, ideally through the mandatory submission of data to a national registry of suprarenal aneurysm repair

Effect of a Flared Renal Stent on the Performance of Fenestrated Stent-Grafts at Rest and Exercise Conditions

Purpose: To quantify the hemodynamic impact of a flared renal stent on the performance of fenestrated stent-grafts (FSGs) by analyzing flow patterns and wall shear stress–derived parameters in flared and nonflared FSGs in different physiologic scenarios. Methods: Hypothetical models of FSGs were created with and without flaring of the proximal portion of the renal stent. Flared FSGs with different dilation angles and protrusion lengths were examined, as well as a nonplanar flared FSG to account for lumbar curvature. Laminar and pulsatile blood flow was simulated by numerically solving Navier-Stokes equations. A physiologically realistic flow rate waveform was prescribed at the inlet, while downstream vasculature was modeled using a lumped parameter 3-element windkessel model. No slip boundary conditions were imposed at the FSG walls, which were assumed to be rigid. While resting simulations were performed on all the FSGs, exercise simulations were also performed on a flared FSG to quantify the effect of flaring in different physiologic scenarios. Results: For cycle-averaged inflow of 2.94 L/min (rest) and 4.63 L/min (exercise), 27% of blood flow was channeled into each renal branch at rest and 21% under exercise for all the flared FSGs examined. Although the renal flow waveform was not affected by flaring, flow within the flared FSGs was disturbed. This flow disturbance led to high endothelial cell activation potential (ECAP) values at the renal ostia for all the flared geometries. Reducing the dilation angle or protrusion length and exercise lowered the ECAP values for flared FSGs. Conclusion: Flaring of renal stents has a negligible effect on the time dependence of renal flow rate waveforms and can maintain sufficient renal perfusion at rest and exercise. Local flow patterns are, however, strongly dependent on renal flaring, which creates a local flow disturbance and may increase the thrombogenicity at the renal ostia. Smaller dilation angles, shorter protrusion lengths, and moderate lower limb exercise are likely to reduce the risk of thrombosis in flared geometries

Introduction of a Team Based Approach to Radiation Dose Reduction in the Enhancement of the Overall Radiation Safety Profile of FEVAR

OBJECTIVES: Fenestrated endovascular aneurysm repair (FEVAR) exposes operators and patients to considerable amounts of radiation. Introduction of fusion of three-dimensional (3D) computed tomography (CT) with intraoperative fluoroscopy puts new focus on advanced imaging techniques in the operating environment and has been found to reduce radiation and facilitate faster repair. The aim of this study is to evaluate the radiation dose effect of introducing a team-based approach to complex aortic repair. METHODS: Procedural details for a cohort of 21 patients undergoing FEVAR after fusion-guided (Modern Group) imaging was introduced are compared with 21 patients treated in the immediate 12 months prior to implementation (Historic Group) at a centre with expertise in FEVAR. Non-parametric tests were used to compare procedure time (PT), air kerma, dose-area product (DAP), fluoroscopy time (FT), estimated blood loss (EBL) and pre- and post-operative estimated glomerular filtration rate (eGFR) between the groups. RESULTS: Change in operative approach resulted in a significant reduction in PT for the Modern group (median 285 mins; interquartile range 268–322) compared with the Historic group (450 mins; IQR 360–540 p = <0.001). There were reductions in skin dose for the Modern group (1.6 Gy; IQR 1.09–2.1) compared with the Historic group (4.4 Gy; 3.2–7.05 p = <0.001), and DAP (Modern 159 Gy.cm2; IQR 123–226 vs 264.93 Gy.cm2; 173.3–366.8 for Historic (p = 0.006). There were no significant differences in FT, and pre- and post-operative eGFR between the two groups. Weight and height were distributed equally across both groups. Structured dose reports including the changes in frame rate were not available for analysis. CONCLUSIONS: Implementation of a team-based approach to radiation reduction significantly reduces radiation dose. These findings suggest that the radiation safety awareness that accompanies the introduction of fusion imaging may improve the overall radiation safety profile of FEVAR for patients and providers

The use of fenestrated and branched endovascular aneurysm repair for juxtarenal and thoracoabdominal aneurysms: a systematic review and cost-effectiveness analysis.

BACKGROUND: Patients with large abdominal aortic aneurysms (AAAs) are usually offered reparative treatment given the high mortality risk. 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. 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. OBJECTIVE(S): 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. DATA SOURCES: 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. REVIEW METHODS: 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. RESULTS: 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. CONCLUSIONS: 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, we have provided detailed methods for the conduct if data becomes available. FUTURE WORK: We recommend 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. STUDY REGISTRATION: This study is registered as PROSPERO CRD42013006051. FUNDING: The National Institute for Health Research Health Technology Assessment programme

Aggressive Surveillance Is Needed to Detect Endoleaks and Junctional Separation between Device Components after Zenith Fenestrated Aortic Reconstruction

Background Junctional separation and resulting type IIIa endoleak is a well-known problem after EVAR (endovascular aneurysm repair). This complication results in sac pressurization, enlargement, and eventual rupture. In this manuscript, we review the incidence of this late finding in our experience with the Cook Zenith fenestrated endoprosthesis (ZFEN, Bloomington, IN). Methods A retrospective review was performed of a prospectively maintained institutional ZFEN fenestrated EVAR database capturing all ZFENs implanted at a large-volume, academic hospital system. Patients who experienced junctional separation between the fenestrated main body and distal bifurcated graft (with or without type IIIa endoleak) at any time after initial endoprosthesis implantation were subject to further evaluation of imaging and medical records to abstract clinical courses. Results In 110 ZFENs implanted from October 2012 to December 2017 followed for a mean of 1.5 years, we observed a 4.5% and 2.7% incidence of clinically significant junctional separation and type IIIa endoleak, respectively. Junctional separation was directly related to concurrent type Ib endoleak in all 5 patients. Three patients presented with sac enlargement. One patient did not demonstrate any evidence of clinically significant endoleak and had a decreasing sac size during follow-up imaging. The mean time to diagnosis of modular separation in these patients was 40 months. Junctional separation was captured in surveillance in 2 patients and reintervened upon before manifestation of endoleak. However, the remaining 3 patients completed modular separation resulting in rupture and emergent intervention in 2 and an aortic-related mortality in the other. Conclusions Junctional separation between the fenestrated main and distal bifurcated body with the potential for type IIIa endoleak is an established complication associated with the ZFEN platform. Therefore, we advocate for maximizing aortic overlap during the index procedure followed by aggressive surveillance and treatment of stent overlap loss captured on imaging