Type Of Endograft Research Articles

A spotter's guide to endovascular endograft recognition

Since the first endovascular aneurysm repair of abdominal aortic aneurysms in the 1980s, there has not only been exponential growth of procedures performed per year, but also rapid proliferation of stent grafts. With the resultant growth in revision and explant procedures on these grafts, we developed this guide to aid trainees in surgery and radiology in identifying these grafts. Our goal with this spotter's guide is to allow the identification of key features from commonly implanted devices radiographically, such as points of fixation, radiopaque markers, and stent patterns. The operative approach for the treatment of endograft complications, including endoleak embolization, aortic cuff extension, laser fenestration, limb extension, and endograft explant is often dramatically impacted by the type of endograft and its individual device characteristics. The intent of this guide is to aid practitioners in identifying endovascular aneurysm repair endografts of all ages, even those that have not been implanted in years.

Nellix Device Failure Mechanisms Analysis on Explanted Grafts.

To understand possible reasons for poor durability of the Nellix (Endologix Inc., Irvine, USA) endovascular aneurysm sealing (EVAS) device. 21 Nellix endoprostheses explanted for endoleaks and migration underwent visual examinations of stent structures and instrumental examinations of the polymer endobags on 4 devices. We harvested 2.0-gram polymer slices out of each of them and tested the samples in an in vitro implantation replication that included wet and dry exposures. During the wet phase, we placed samples in a beaker with saline, mimicking the filling of the endobags during implantation. An exposure to a 37°C environment with 60% humidity during the dry phase replicated the postimplantation conditions inside the aneurysmal sac. Iatrogenic defects affected 16 (76%) metal stents and 20 (95%) endobags. The polymer was disintegrated owing to degradation in 15 (71%) cases. The polymer could lose more than 70% of its initial weight when partially dehydrated and regain 80% when placed in saline. We observed volume decrease and polymer fragmentation during these study phases. The polymer can lose weight and volume while it dehydrates. This structural degradation of the polymer could lead to the development of endoleaks and/or migration of the device. Based on the results of previous investigations, due to possible endovascular device degradation, patients with endografts should be offered life-long surveillance, and the Nellix device is no exception. Herein we suggest polymer degradation as one of the possible reasons for the device failure. Although Nellix has been withdrawn from the market, there are numerous patients with this type of endograft. Due to its unpredictable performance in the medium and long term, these patients should be recommended enhanced life-long surveillance every 6 months. Any suspicious conditions during the follow-up must be taken seriously and explantation should be considered.

Type III Endoleak Incidence and Outcomes in Endovascular Aortic Repair: Comparison of Anatomical and Proximal Fixation Devices.

To evaluate the influence of endograft fixation type on the incidence, treatment, and outcomes of type III endoleaks (TIIIELs). Abdominal aortic aneurysms (AAAs) treated with bifurcated endografts between 1994 and 2020 were prospectively collected and reviewed. The endograft included were classified as "Anatomical Fixation" (AF) (Powerlink [Endologix] and AFX [Endologix]) or "Proximal Fixation" (PF). The primary outcome was the incidence of TIIIEL over time, stratified by fixation type. Secondary outcomes included between-group comparisons of baseline characteristics, intraoperative details during TIIIEL correction, and survival analysis after TIIIEL diagnosis. A total of 2065 endovascular aneurysm repairs were performed: 872 (42.2%) with AF and 1193 (57.8%) with PF devices. The estimated incidence of TIIIEL at 1, 5, and 10 years was 0.4%, 4.2%, and 7.3%, and 0.5%, 3.2%, and 4.6% for AF and PF, respectively (p=0.157), and fixation type was not associated with TIIIEL development in the competing risk regression model (p=0.101). The cumulative overall survival rate in patients diagnosed with TIIIEL did not differ significantly between the groups (p=0.077). The rate of recurrent TIIIELs was significantly lower in the AF group (7.1% vs 22.7%; p=0.044); however, no significant difference was found in secondary reintervention between the two groups (11.9% vs 27.3%, p=0.074). Patients with angulated and calcified aortic neck (SHR 3.4, 95% CI 1.2-9.6, p=0.022) and larger aneurysms (SHR 1.2; 95% CI 1.1-1.3; p<0.001) had a higher risk of TIIIEL. Likewise, the use of three or more endograft components increased the risk of TIIIEL by 3.1 times (SHR 3.1; 95% CI 1.7-5.4; p<0.001). The occurrence of TIIIELs was not affected by the type of endograft fixation. For larger abdominal aortic aneurysms (AAAs) and aneurysms with angulated and calcified aortic necks, there is a higher likelihood of developing TIIIELs during follow-up, regardless of the endograft type used. The type of fixation does not influence the incidence of TIII ELs. EVAR in larger AAAs and aneurysms with angulated and calcified aortic necks have a higher risk of developing TIII EL. Moreover, the risk of TIII EL is considerably increased by the use of three or more modular components.

Standardized approach for four-fenestrated physician-modified endograft to treat complex abdominal aortic aneurysms using Valiant Captivia

We describe the feasibility and safety of a standardized approach for four-fenestrated physician-modified endograft (PMEG) placement to treat complex abdominal aortic aneurysms using the Valiant Captivia platform (Medtronic). The standardization is based on specific selection criteria for anatomical feasibility, measurement method, and modification technique of a single endograft type. Six cases (two juxtarenal, two pararenal, and two type IV thoracoabdominal aneurysms) were treated, with 24 target vessels incorporated with fenestrations. Four cases were treated in an urgent setting and two were elective. The time modification required was 121 ± 18 minutes. Technical success was 100%, with no mortality or complications at 30 days. Postoperative computed tomography at 3 months demonstrated complete aneurysm exclusion, without a type I or III endoleak, no main graft- or fenestration-related loss of integrity, and no target vessel misalignment or stent fracture. The present standardized approach seems safe and feasible and might represent an initial benchmark for comparison with future studies.

Optimization of the proximal sealing in thoracic endovascular aortic repair (TEVAR)

Thoracic endovascular aortic repair (TEVAR) today represents the first option for the treatment of most pathologies involving the descending thoracic aorta. Proximal endograft failure, which includes endograft migration or type IA endoleak, represents the most frequent complication during the mid-term and long-term period. Proximal sealing length is the single most important factor affecting the technical success and durability of TEVAR. Other factors related to aortic arch anatomy, fluid dynamics, type of endograft, or type of pathology, may influence the risk of proximal endograft failure, and should be considered during the endovascular planning of the proximal sealing length. This review summarizes the evidence on the factors affecting the risk of proximal endograft failure, and provides the rationale for the choice of the proximal sealing length during TEVAR, based on specific patients’ characteristics.

Patients’ Radiation Exposure During Endovascular Abdominal Aortic Aneurysm Repair

To investigate associations between patient characteristics, intraprocedural complexity factors, and radiation exposure to patients during endovascular abdominal aortic aneurysm repair (EVAR). Elective standard EVAR procedures between January 2015 and December 2020 were retrospectively analyzed. Patient characteristics and intraprocedural data (i.e., type of device, endograft configuration, additional procedures, and contralateral gate cannulation time [CGCT]) were collected. Dose area product (DAP) and fluoroscopy time were considered as measurements of radiation exposure. Furthermore, effective dose (ED) and doses to internal organs were calculated using PCXMC 2.0 software. Descriptive statistics, univariable, and multivariable linear regression were applied to investigate predictors of increased radiation exposure. The 99 patients were mostly male (90.9%) with a mean age of 74±7years. EVAR indications were most frequently abdominal aortic aneurysm (93.9%), penetrating aortic ulceration (2.0%), focal dissection (2.0%), or subacute rupture of infrarenal abdominal aortic aneurysm (2.0%). Median fluoroscopy time was 19.6minutes (interquartile range [IQR], 14.1-29.4) and median DAP was 86,311 mGycm2 (IQR, 60,160-130,385). Median ED was 23.2 mSv (IQR, 17.0-34.8) for 93 patients (93.9%). DAP and ED were positively correlated with body mass index (BMI) and CGCT. Kidneys, small intestine, active bone marrow, colon, and stomach were the organs that received the highest equivalent doses during EVAR. Higher DAP and ED values were observed using the Excluder endograft, other bi- and tri-modular endografts, and EVAR with ≥2 additional procedures. Multivariable linear regression analysis revealed that BMI, ≥2 additional procedures during EVAR, and CGCT were independent positive predictors of DAP and ED levels after accounting for endograft type. Patient-related and procedure-related factors such as BMI, ≥2 additional procedures during EVAR, and CGCT resulted predictors of radiation exposure for patients undergoing EVAR, as quantified by higher DAP and ED levels. The main intraprocedural factor that increased radiation exposure was CGCT. These data can be of importance for better managing radiation exposure during EVAR.

Diminishing Endograft Apposition during Follow-Up Is an Important Indicator of Late Type 1a Endoleak after Endovascular Aneurysm Repair.

Late type 1a endoleaks (T1aELs) after endovascular aneurysm repair (EVAR) are hazardous complications which should be avoided. This study investigated the evolution of the shortest apposition length (SAL) post-EVAR and hypothesised that a declining apposition during follow-up may be an indicator of T1aEL development. Patients with a late T1aEL were selected from a consecutive multicentre database. For each T1aEL patient, the preoperative computed tomography angiography (CTA), first postoperative CTA, and pre-endoleak CTA were analysed. T1aEL patients were matched 1:1 to uncomplicated controls, based on endograft type and follow-up duration. Anatomical characteristics and endograft dimensions, including the post-EVAR SAL, were measured. Included were 28 patients with a late T1aEL and 28 matched controls. The SAL decreased from 11.2 mm (5.6-20.6 mm) to 3.9 mm (0.0-11.4 mm) in the T1aEL group (p = 0.006), whereas an increase in SAL was seen in the control group from 21.3 mm (14.1-25.8 mm) to 25.4 mm (19.0-36.2 mm; p = 0.015). On the pre-endoleak CTA, 18 patients (64%) in the T1aEL group had a SAL < 10 mm, and one (4%) patient in the control group had a SAL < 10 mm on the matched CTAs. Moreover, three mechanisms of decreasing sealing zone were identified, which might be used to determine optimal imaging or reintervention strategies. Diminishing SAL < 10 mm is an indicator for T1aEL during follow-up, it is imperative to include apposition analysis during follow-up.

A Scoping Review on the Incidence, Risk Factors, and Outcomes of Proximal Neck Dilatation after Standard and Complex Endovascular Repair for Abdominal Aortic Aneurysms.

Background: To define proximal neck dilation (PND) after standard endovascular aneurysm repair (EVAR) and fenestrated EVAR (FEVAR), determining: incidence and risk factors; evidence base that links PND to outcomes of patients; recurring themes or gaps in the literature. Methods: We performed a scoping review and included only full-text English articles with follow-up focusing on PND in patients undergoing EVAR or FEVAR, published between 2000 and 2022. The following PICO question was used to build the search equation: in patients with abdominal-aortic-aneurysm (AAA) (Population) undergoing endovascular repair (Intervention), what are the incidence, risk factors and prognosis of radiologically defined PND (Comparison) on short-term and long-term outcomes (Outcomes)? Results: 15 articles were included after review. Measurement protocols for proximal aortic neck (PAN) varied among individual studies and the definition of PND resulted as heterogeneous. Rate of patients with a PND ranged between 0% and 41%. Large proximal neck (>28 mm) and excessive graft sizing (30%) were predictors for PND. New endografts with low outward radial forces and FEVAR seemed to be protective. Surgical conversion was the definitive option in the case of patients unfit for other endovascular treatments. Conclusions: PND is a frequent finding after EVAR and FEVAR. Excessive graft oversizing and large baseline PAN were predictors of neck enlargement, independently by the type of standard endograft used. FEVAR may be considered protective against complications, together with endografts using low outward radial forces. Lifelong radiological follow-up is mandatory.

Renal outcomes of suprarenal vs. infrarenal endograft fixation in endovascular abdominal aortic aneurysm repair: a narrative review.

Background and ObjectiveAbdominal aortic aneurysm (AAA) is a common pathology with a prevalence of 4.8%. AAA rupture is associated with significant mortality and so early diagnosis followed by regular monitoring is needed until treatment might be considered and plan intervention. Endovascular aneurysm repair (EVAR) is an established and effective alternative to open surgical repair (OSR) in the treatment of AAAs. Key parameters in defining conventional EVAR suitability include the infrarenal neck length and angulation for the fixation of the proximal graft component. Endograft fixation can be either suprarenal or infrarenal and much debate exists as to which approach is associated with optimum renal outcomes. This study aims to review the current literature with respect to the renal outcomes associated with conventional EVAR using suprarenal fixation (SRF) vs. infrarenal fixation (IRF).MethodsA search was conducted from major search indices (PubMed, Google Scholar and EMBASE) to identify relevant literature pertaining to renal outcomes in EVAR. Recent papers comparing SRF and IRF were evaluated and their findings discussed.Key Content and FindingsThe mechanism of renal function decline (RFD) following EVAR is uncertain and likely multifactorial. Aortic morphology, endograft type and surgical technique may all contribute to RFD. There is a significant degree of heterogeneity within the literature regarding study design and definitions of RFD. Recent literature suggests that RFD is more acute for SRF than IRF in the first post-operative year, but the clinical significance of this decline in patients with normal kidney function is questionable. Studies indicate that SRF is associated with accelerated RFD at 5 years, and that the RFD is worse in patients who are female and who have pre-existing renal insufficiency.ConclusionsSRF is associated with a greater decline in renal function than IRF in both short- and long-terms. Although clinically insignificant in the short-term, the limited available long-term evidence suggests that SRF results in a relatively accelerated decline in renal function when compared to IRF, but it is possibly partially explained by the higher prevalence of advanced degenerative/atherosclerotic disease in SRF cohorts. These trends are noted particularly in female patients and in patients with baseline renal insufficiency.

Limb Graft Occlusion Following Endovascular Aneurysm Repair for Infrarenal Abdominal Aortic Aneurysm with the Zenith Alpha, Excluder, and Endurant Devices: a Multicentre Cohort Study

Limb graft occlusion (LGO) is a serious complication after endovascular aneurysm repair (EVAR) and while device development enables treatment of increasingly complex aortic anatomy, little is known about how endograft type affects the risk of occlusion. This observational study aimed to explore the incidence of LGO after EVAR for three major endograft systems. All patients with standard EVAR as the primary intervention for infrarenal abdominal aortic aneurysm (AAA), between January 2012 and December 2018, at five Swedish vascular surgery centres, were included in this multicentre retrospective cohort study. LGO was defined as a total limb occlusion regardless of symptoms, or a treated significant stenosis. A nested case control (NCC) design with incidence density sampling of 1:3 was used for analysis of potential per-operative and morphological risk factors. Conditional logistic regression was used to estimate multivariable odds ratios (OR) with 95% confidence intervals (CI) RESULTS: A total of 924 patients were included. The majority were male (84%), the mean age was 76 years (± 7.5 SD), and median AAA diameter was 59 mm (IQR 55, 67). Patients were treated with Zenith Alpha (n= 315, ZISL limbs), Excluder (n= 152, PLC/PXC limbs), and Endurant (n= 457, ETLW/ ETEW limbs). During median follow up of 37 months (IQR 21, 62), 55 occlusions occurred (5.9%); 39 with Zenith Alpha (12.4%), one with Excluder (0.7%), and 15 with Endurant (3.3%). In the NCC analysis, the Zenith Alpha device (OR 5.31, 95% CI 1.97 - 14.3), external iliac artery (EIA) landing (OR 5.91, 95% CI 1.30 - 26.7), and EIA diameter < 10 mm (OR 4.99, 95% CI 1.46 - 16.9) were associated with an increased risk of LGO. Endograft device type is an independent risk factor for LGO after EVAR. Specifically, the Zenith Alpha demonstrated an increased risk of LGO compared with the Endurant and Excluder devices. In addition, a narrow EIA and landing zone in EIA are also risk factors for LGO.

A Five-Year Computed Tomography Follow-up Study of Proximal Aortic Neck Dilatation After Endovascular Aortic Repair Using Four Contemporary Types of Endograft.

This study analysed the progression of proximal aortic neck diameter in patients with asymptomatic abdominal aortic aneurysms, treated by endovascular aortic repair using four different, contemporary types of endograft. This is a retrospective study of four cohorts of 30 patients presenting with asymptomatic abdominal aortic aneurysms and treated with endovascular aortic repair using four different types of contemporary endografts, namely Endurant® (Medtronic), Excluder® (W.L. Gore), Zenith® (Cook Medical) and Ovation® (Endologix) endografts. Patients' demographics and aortic aneurysm measurements, including suprarenal aortic, proximal infrarenal neck and maximum aortic aneurysmal diameter, were gathered from the patients' electronic medical records, pre- and post-interventional computed tomography studies, respectively. Diameter measurements were modelled as a function of endograft type; an interaction test was used to test whether the evolutions over time were different between the four types of endograft. Suprarenal aortic diameter increased over time (P = 0.0235) and maximum aortic aneurysm diameter decreased over time (P = 0.0008) in the four types of endograft. The progressive increase in proximal neck diameter from preoperative baseline up to five years of follow-up was 1.20mm for Endurant (P = 0.0054), 1.72mm for Ovation (P = 0.0006), 1.14mm for Excluder (P = 0.0102) and 2.83mm for Zenith (P < 0.0001), respectively. Five patients (4%) presented with a late-type 1a endoleak: Endurant (n = 1); Ovation (n = 2) and Zenith (n = 2). All endografts were associated with a progressive dilatation of the proximal aortic neck over a time interval of five years and may be associated with late-type 1a endoleak.

The association between perioperative embolization of hypogastric arteries and type II endoleaks after endovascular aortic aneurysm repair

ObjectiveType II endoleaks (T2ELs) are the most common type of endoleak after endovascular aneurysm repair (EVAR). The iliolumbar artery arising from the hypogastric artery is often a major source of T2ELs, and transarterial embolization of the iliolumbar artery through the hypogastric artery is sometimes performed to interrupt sac expansion during follow-up. Considering the equivocal results of an association between hypogastric embolization and T2ELs in previous studies, this topic has re-emerged after the advent of iliac branch devices. This study reviewed our series to clarify whether hypogastric embolization is associated with T2ELs at 12 months after EVAR. MethodsPatients who underwent elective EVAR between June 2007 and May 2017 at our institution were retrospectively reviewed. Patients with postoperative computed tomography angiography (CTA) at 12 months were included. Patients in whom CTA revealed type I or type III endoleaks during follow-up, who required reinterventions before 12 months, and who had solitary iliac aneurysms were excluded. The primary outcome was the incidence of T2ELs at 12 months after EVAR. The associations of patients' characteristics, anatomic factors, hypogastric embolization, and type of endograft with the primary outcome were analyzed. ResultsIn total, 375 patients were enrolled. During the median follow-up of 59.5 months (interquartile range, 19-126 months), 40 patients died, and 50 reinterventions were performed. In 108 patients (28.8%), either hypogastric artery was embolized to extend distal landings to the external iliac artery. Bilateral and unilateral embolization was performed in nine and 99 patients, respectively. In total, 153 patients (40.8%) had T2ELs found by CTA at 12 months. In the univariate analysis, the status of hypogastric artery occlusion or embolization was not significantly different between patients with and without T2ELs. However, there were not enough patients to detect a 10% difference in T2ELs with >80% statistical power. In the multivariate analysis, significant associations with T2EL were observed for female sex (P = .049), patent inferior mesenteric artery (P = .006), and presence of five or more patent lumbar arteries (P < .001) but not for hypogastric embolization. In addition, compared with the Zenith (Cook Medical, Bloomington, Ind) endograft, the Excluder (W. L. Gore & Associates, Flagstaff, Ariz) endograft was significantly related to T2EL (P = .001). ConclusionsNo significant association between hypogastric embolization and T2EL was demonstrated in this retrospective study, which lacked adequate statistical power.

Post-implantation syndrome: the impact of different devices for endovascular abdominal aortic aneurysm repair and related etiopathogenetic implications.

Postimplantation syndrome (PIS) is a systemic inflammatory response occurring in early phase after abdominal aortic aneurysm (AAA) endovascular repair (EVAR). PIS can also occur after endovascular aneurysm sealing (EVAS) with Nellix system which prevent new onset of mural thrombus inside. Aim was to compare the incidence of PIS after EVAS and EVAR to evaluate the possible role of the new-onset thrombus inside the aneurysmal sac. Secondary aims were to assess the effect of AFX (Endologix) endoskeleton compared with other commercially available exoskeleton PTFE stent grafts on inflammatory response and its relationship with the clinical outcomes. From 2013 to 2017, data on 60 elective EVAS with Nellix system (Endologix, Irvine, CA, USA) and 110 EVAR with ePTFE devices (56 AFX devices and 54 other stent grafts) for AAA patients were retrospectively collected. PIS was defined as composite of body temperature ≥38 °C coinciding with leukocyte count >12,000/mL and hs-CPR >10 mg/L. New-onset thrombus volume after EVAR was calculated by: endograft volume - preoperative luminal volume=volume of new-onset thrombus, whereas post-EVAS thrombus volume was calculated from difference between AAA volume and volume of Nellix endobags, including balloon expandable stents. Nonparametric χ2 distribution with corresponding P values were used to assess differences among categorical variables with regard to endograft type. Threshold of statistical significance was P<0.05. Subgroup analysis of outcomes by stent-graft design was performed using independent-samples t-test. EVAS with Nellix system was associated with lower incidence of PIS compared to EVAR using both AFX device and other endografts (8.3%, 30%, 35%, respectively, P=0.001). No significant new-onset of mural thrombus occurred following EVAS while an avarage new-onset thrombus of 21% and 14% was found in EVAR group A and group B, respectively. No statistically significant difference of PIS incidence was observed after endoskeleton AFX device deployment compared with other EVAR exoskeleton endografts. During follow-up, major complications were proportionally but not significantly (P=0.43) less frequent after EVAS (10.3%) than after EVAR and after EVAR using AFX device (8.9%) than after EVAR with other PTFE stent grafts (16.4%). The etiology and pathophysiology of PIS is not yet well understood. It is speculated that the type of the stent graft or the mural thrombus within the AAA may play a role in determing this inflammatory response. In this study, PIS was significantly less frequent after EVAS than EVAR. The lower inflammatory reaction observed after EVAS might be related to the endobags of Nellix system which completely seal the aneurysm sac reducing the new onset of mural thrombus. This could confirm the role of new-onset mural thrombus in the genesis of PIS. The systemic inflammatory response does not significantly differ after endoskeleton AFX device deployment compared with other EVAR exoskeleton stent grafts. PIS does not seem to have any significant prognostic implications in terms of major adverse events.

Partial Endograft Removal Preserves the Aortic Walls During Delayed Open Conversions of Endovascular Aortic Repair

Open conversion of endovascular aortic repair (EVAR) is the first-choice treatment in case of endograft failure or high-flow endoleak. However, the traditional technique based on the total removal of the endograft can produce injuries of the aortic walls, with severe consequences on the anastomoses quality. Our aim is to show the advantages of the partial endograft removal on the aortic integrity by reporting a case series including 25 delayed open conversion performed with this technique. A retrospective study was conducted over the cases of delayed open conversions performed in the last 30months. Demographics, past medical history, endograft type, causes for conversions, and early and mid-term outcomes were recorded and analyzed in relation with the technique employed (partial vs total endograft removal). Between September 2016 and March 2019, 25 consecutive cases of EVAR failure were converted to open treatment. In all cases, the endografts were resected leaving in place part of the iliac branches, and, whenever possible, also the proximal stent of the main body. Primary technical success was achieved in 100% of cases. Disease-free survival over 18-month median follow-up was 100%. All patients underwent abdominal aortic duplex scan controls as scheduled, with no early or late postoperative complication. No anastomotic aneurysms or any surgery-related complications were observed. Partial endograft removal is a safe and effective technique that could be used to protect the aortic integrity in delayed open conversions of EVAR.

Supra-aortic Remodeling After EVAR During One-year Follow-up: Comparison Between Three Different Fixation Types of Endografts

Introduction -The remodeling of the supra-renal aorta after endovascular aortic aneurysm repair (EVAR) in relation to different endograft design has not been fully investigated. The aim of this study was to assess the anatomic changes in supra-renal aorta post-EVAR with the use of different types of endografts during the first year. Methods - In total 100 patients undergoing EVAR with 3 types of endografts having different proximal fixation system were retrospectively analyzed. Fifty consecutive patients were treated with Ovation (supra-renal fixation and infra-renal sealing with polymer ring; Endologix, Irvin, CA, USA), 25 with Endurant (supra-renal fixation; Medtronic Cardiovascular, Santa Rosa, Calif, USA), and 25 with Excluder (infra-renal fixation; W.L. Gore & Associates, Flagstaff, AZ, USA). Baseline calcification (0 to 2) and thrombus (0 to 2) at the neck, co-morbidities and anatomical variables were recorded. Anatomic variables were AAA maximum diameter, supra-renal neck angulation, and diameters of the supra-renal aorta at 5mm, 15mm, 25mm, and 35mm above the most cephalad renal artery. Computed tomography angiography (CTA) was obtained pre-operatively at 1 and 12 months post-EVAR. Results - The mean AAA diameter was 56.5mm, 57mm and 55mm in Ovation, Endurant and Excluder group, respectively. Co-morbidities were not different across the 3 groups. Presence and amount of neck calcification (p=0.139) and thrombus (p=0.116) was similar among groups. Maximum aortic diameter showed significant reduction from pre-operative to 12-month post-operative CT scan for all 3 groups. (Ovation group: 56.5mm to 53mm; p<0.001, Endurant group: 57mm to 51mm; p<0.001, Excluder group: 55mm to 50mm; p<0.001). Regarding supra-renal aortic diameter changes, only the Ovation group showed a significant increase at all levels (mean increase of 1mm), except at 15mm which remained stable. Changes in supra-renal angulation were also significant only in the Ovation group (100, 80, 70; p<0.001) and Excluder group (220, 200, 180; p=0.05). Among the three different endografts, maximum diameter decrease, was not different (p=0.99), supra-renal aortic diameter increase, was significantly higher only in Ovation group at levels of 5mm (p=0.02) and 25mm (p=0.01) while there were no differences observed at the level of 15mm (p=0.12) and 35mm (p=0.25) and supra-renal angulation reduction was not different (p=0.7). No migration or endoleak type I was observed in any patient. Endoleak type II was observed in 18/50, 6/25 and 7/25 in Ovation, Endurant and Excluder group, respectively, (p=0.532). Conclusion - The type of endograft fixation system appears to have different impact on supra-aortic anatomy in terms of supra-renal aortic diameter and anglulation, but without any clinical effect in the first post-EVAR year. Longer follow up is needed to clarify future remodeling and clinical impact of these observations and whether any type of endograft requires more intense follow up.

Urgent Late Open Conversions after Endovascular Abdominal Aneurysm Repair: A Multicentre Experience

Introduction - Late open conversions (LOC) after EVAR are associated with a considerably increased perioperative morbidity and mortality as compared to standard EVAR or open repair. Additionally, since the number of patients undergoing EVAR is increasing, the incidence of LOC performed for ruptured aneurysms or infected endografts will likely rise in the future. Here we report a multicentre experience of urgent LOC, with the goal of identifying technical aspects and outcomes that may alter clinical management. Methods - A retrospective analysis of EVAR requiring urgent LOC (>30 days after implantation) from 1996 to 2016 in six Vascular Centres was performed. Specifically, patients who presented with aneurysm rupture or other conditions (such as graft thrombosis, infection or aneurysm growth associated with pain) which required urgent surgery (<24h) were selectively included. Patients' demographics, duration of implant, type of endograft, previous attempts of endovascular correction, reason for LOC, operative technique (clamping site, partial or complete graft removal), 30-day mortality and post-operative complications were obtained for analysis. Long-term survival was also evaluated. Results - During the study period, 140 patients underwent LOC in the participant institutions. Among these, 42 were operated in a urgent setting and were therefore analyzed. Mean age at conversion was 75.8±9 years; 88.1% were male. Grafts were excised after a median of 37 months (range: 1.6-132.1). Multiple types of endografts have been explanted: 30/42 bifurcated endografts, 5/42 tubes, 5/42 aorto-uni-iliac and 2/42 iliac side-branch devices. A suprarenal fixation was present in the 66.7% of the endografts. Eleven patients (26.2%) underwent endovascular reintervention for endoleak repair prior to LOC. Indications for urgent LOC were: aneurysm rupture in 24/42 cases (57.1%), endograft infection in 10/42 (23.8%), endoleaks associated with aneurysm growth and pain in 6/42 (14.3%) and recurrent endograft thrombosis in 2/42 (4.8%). Proximal aortic cross-clamping site was infrarenal in 38.1% of the cases, suprarenal in 19% and supraceliac in 42.9%. Complete removal of the stent-graft was performed in 32 patients (72.6%), partial removal in the remaining 10 cases (with preservation of the proximal portion in 7/10 cases). Reconstructions were performed with dacron grafts in 33/42 cases, cryopreserved arterial allografts in 5/42 and endograft removal associated with prosthetic axillo-bi-femoral bypass in 4/42. Overall 30-day mortality was 21.4%. A suprarenal clamping site was associated with a statistically significant higher mortality rate of 34.6% (p=.007). During follow-up, we experienced 1 aneurysm-related death due to the rupture of an aortic stump. The estimated 1- and 5-year survival rates were 62% and 46%, respectively. Conclusion - Urgent LOC after EVAR are associated with high postoperative mortality rates and poor long-term survival. The need of a suprarenal clamping is associated with worse outcomes. A close follow-up after EVAR is mandatory, since early decision for elective LOC may improve postoperative outcomes in this subgroup of patients. Further studies are eagerly awaited to better define the timing and the best treatment option for failing EVAR, since a standardization of the surgical technique may improve patients' survival.

Retrospective Comparative Study on Differences in Presence of Gas in the Aneurysm Sac After Evar in Early Post-operative Period Between Carbon Dioxide Flushing Technique and Saline Flushing of the Delivery-system

Introduction: Presence of gas is a frequent finding on early postoperative computed tomography angiography (CTA) after endovascular aortic aneurysm repair (EVAR) with unclear clinical relevance. The aim of this study was to examine and compare the presence of gas within the aneurysm sac following EVAR on early postoperative CTA after the use of carbon-dioxide (CO2) flushing technique with saline flushing alone. Methods: A retrospective analysis of patients undergoing standard, fenestrated EVAR (fEVAR) or branched EVAR (bEVAR) with flushing of the delivery system with CO2 between January 2016 and August 2018 was undertaken. Data of a previous report using standard saline flushing was included. Patients were classified into two main groups; group 1 with saline flushing and group 2 with CO2 flushing and three sub-groups according to the type of endo-graft. The presence, position and volume of gas in the postoperative CTA (within 10 days) was examined and analyzed in terms of anatomical and procedural risk factors. Results: Group 1 included 210 patients (mean age 73±8, 84% males) while Group 2 included 300 patients (mean age 70± 11, 68% males). Presence of gas was more common in group 1 (83; 39% vs. 64; 21%, p= 0.000). Volume of gas was larger in group 1 (0.41ml; (0.01-2.7) vs. 0.2ml; (0.02 - 1), p= 0.001). In standard EVAR with saline flushing (subgroup 1a); 59 patients (45%) had presence of gas and with CO2 flushing (subgroup2a); 35 patients (25%) had presence of gas (p= 0.005). The mean gas volume was larger in subgroup 1a compared to 2a (0.40± 0.47ml vs 0.15± 0.17ml, p= 0.000). The location of the gas was more frequent in contact with the anterior wall of the aorta in both groups, standard EVAR subgroups and fEVAR subgroups. The presence of gas in group 2 was associated with larger pre-operative size of the aortic diameter (p= 0.03) and larger perfused lumen diameter (p= 0.05). The type of the graft was not associated with the presence of gas in the aneurysm sac on post-operative CTA. However, the presence of gas was more frequent in standard EVAR than fEVAR and bEVAR. Endoleak type II was not associated with the presence of gas. Conclusion: CO2 flushing of stent-grafts during standard and complex EVAR prior to deployment reduces the frequency and volume of gas on post-operative CTA. This study indicates, that the CO2 flushing technique may effectively exchange trapped air for a less harmful gas in endo-grafts. Disclosure: Tilo Kölbel has intellectual property with Cook Medical, receives royalties, research, travel and educa-tional grants, speaking fees and is consultant and proctor with Cook Medical. Nikolaos Tsilimparis re-ceives travel and educational grants, speaking fees and is proctor with Cook Medical.

Retrospective Comparative Study on Differences in Presence of Gas in the Aneurysm Sac after Endovascular Aortic Aneurysm Repair in Early Postoperative Period between Carbon Dioxide Flushing Technique and Saline Flushing of the Delivery System

Presence of gas is a frequent finding on early postoperative computed tomography angiography (CTA) after endovascular aortic aneurysm repair (EVAR) with unclear clinical relevance. The aim of this study is to examine and compare the presence of gas within the aneurysm sac following EVAR on early postoperative CTA after the use of carbon dioxide (CO2) flushing technique with saline flushing alone. A retrospective analysis of patients undergoing standard, fenestrated EVAR (fEVAR) or branched EVAR (bEVAR) with flushing of the delivery system with CO2 between January 2016 and August 2018 was undertaken. Data of a previous report using standard saline flushing were included. Patients were classified into 2 main groups: group 1 with saline flushing and group 2 with CO2 flushing and 3 subgroups according to the type of endograft. The presence, position, and volume of gas in the postoperative CTA (within 10days) was examined and analyzed in terms of anatomical and procedural risk factors. Group 1 included 210 patients (mean age 73±8, 84% males), while group 2 included 300 patients (mean age 70±11, 68% males). Presence of gas was more common in group 1 (83, 39% vs. 64, 21%, P=0.000). Volume of gas was larger in group 1 [0.41mL (0.01-2.7) vs. 0.2mL (0.02-1), P=0.001). In standard EVAR with saline flushing (subgroup 1a), 59 patients (45%) had presence of gas with CO2 flushing (subgroup 2a); 35 patients (25%) had presence of gas (P=0.005). The mean gas volume was larger in subgroup 1a compared to 2a (0.40±0.47 vs. 0.15±0.17mL, P=0.000). The location of the gas was more frequent in contact with the anterior wall of the aorta in both groups, standard EVAR subgroups and fEVAR subgroups. The presence of gas in group 2 was associated with larger preoperative size of the aortic diameter (P=0.03) and larger perfused lumen diameter (P=0.05). The type of the graft was not associated with the presence of gas in the aneurysm sac on postoperative CTA. However, the presence of gas was more frequent in standard EVAR than fEVAR and bEVAR. Endoleak type II was not associated with the presence of gas. CO2 flushing of stent grafts during standard and complex EVAR prior to deployment reduces the frequency and volume of gas on postoperative CTA. This study indicates that the CO2 flushing technique may effectively exchange trapped air for a less harmful gas in endografts.

Endograft migration after thoracic endovascular aortic repair

ObjectiveThe objective of this study was to evaluate the incidence, timing, and potential risk factors of late endograft migration after thoracic endovascular aortic repair (TEVAR). MethodsA retrospective analysis was conducted of 123 patients receiving TEVAR for thoracic aortic aneurysms (TAAs), dissections, penetrating aortic ulcer, intramural hematoma, or traumatic transection between January 2005 and December 2015 with a minimum imaging-based follow-up of 6 months. Imaging analysis was performed by three independent readers. Migration was defined according to the reporting standards as a stent graft shift of >10 mm relative to a primary anatomic landmark or any displacement that led to symptoms or required therapy. A standardized measurement protocol in accordance with the reporting guidelines was used. Median follow-up was 3 years (range, 0.5-10 years). ResultsMigration occurred in nine (7.3%) patients and took place at the proximal landing zone (n = 1), overlapping zone (n = 4), or distal landing zone (n = 5), resulting in type I or type III endoleaks in 44% (n = 4/9) of the cases. All cases of migration with endoleaks underwent reintervention; 75% (n = 3/4) of the migration associated with endoleaks could have been identified on previous imaging before an endoleak occurred. Freedom from migration was 99.1% after 1 year, 94.0% after 3 years, and 86.1% after 5 years. Aortic elongation and TAA were identified as predisposing factors for migration (P = .003 and P = .01, respectively). No influence of the proximal landing zone (zone 0-4), type of aortic arch (I-III), or type of endograft on the incidence of migration was found. ConclusionsGraft migration after TEVAR occurs in a relevant proportion of patients, predominantly in patients with TAA and aortic elongation. Follow-up imaging of these patients should be specifically evaluated regarding the occurrence of migration.

Assessment of geometrical remodelling of the aortic arch after hybrid treatment.

The aim of this study was to measure the morphological remodelling of the ascending aorta, aortic arch and thoracic aorta after aortic arch hybrid treatment including debranching and stent graft implantation. Preoperative, 1-month and 1-year follow-up of computed tomography angiography scans of 22 patients were analysed to compute the lumen centreline from the aortic root to the coeliac trunk, and the following measurements were derived: the total centreline length, distance from the aortic root to the left subclavian artery, distance from the left subclavian artery to the distal landing zone. For both pre- and postoperative centrelines, the pointwise curvature was measured at the proximal and the distal landing zones. The mean curvature values of the whole aortic segment and the endografting region of the ascending and the descending aorta were measured. Surface outerline was computed as well, and curvature values at the endograft landing points were extracted. At the 1-month follow-up, centreline length were already significantly increased (382.66 ± 48.69 to 388.1 ± 50.75 mm; P = 0.01). Centreline pointwise curvature increased in the proximal (+29%, P = 0.011) and the distal zones (+63%, P = 0.004). Similarly, pointwise curvature of the outerline significantly increased in the proximal (+77%, P = 0.01) and the distal landing zones (+100%, P = 0.04). The centreline mean curvature increased in the ascending aorta (+7%, P = 0.02) and decreased in the endografting region (-3.3%, P = 0.004). No evidence of a relationship of such a remodelling with the type of endograft and the type of pathology was observed. This remodelling trend was confirmed by the analysis of 1-year computed tomography angiographies. Hybrid arch repair was associated with a significant elongation of the vessel and a significant increase in the curvature on the ascending aorta and the descending aorta and on the endograft proximal and the distal landing zones.