Risk Factors for Proximal Neck Complications After Endovascular Aneurysm Repair Using the Endurant Stentgraft

A computational study of artery curvature and endograft oversize influence on seal zone behavior in endovascular aortic repair

Thoracic endovascular aortic repair (TEVAR) is a minimally invasive procedure involving the placement of an endograft inside the dissection or an aneurysm to direct blood flow and prevent rupture. A significant challenge in endovascular surgery is the geometrical mismatch between the endograft and the artery, which can lead to endoleak formation, a condition where blood leaks between the endograft and the vessel wall. This study uses computational modeling to investigate the effects of artery curvature and endograft oversizing, the selection of an endograft with a larger diameter than the artery, on endoleak creation. Finite element analysis is employed to simulate the deployment of endografts in arteries with varying curvature and diameter. Numerical simulations are conducted to assess the seal zone and to quantify the potential endoleak volume as a function of curvature and oversizing. A theoretical framework is developed to explain the mechanisms of endoleak formation along with proof-of-concept experiments. Two main mechanisms of endoleak creation are identified: local buckling due to diameter mismatch and global buckling due to centerline curvature mismatch. Local buckling, characterized by excess graft material buckling and wrinkle formation, increases with higher levels of oversizing, leading to a larger potential endoleak volume. Global buckling, where the endograft bends or deforms to conform to the centerline curvature of the artery, is observed to require a certain degree of oversizing to bridge the curvature mismatch. This study highlights the importance of considering both curvature and diameter mismatch in the design and clinical use of endografts. Understanding the mechanisms of endoleak formation can provide valuable insights for optimizing endograft design and surgical planning, leading to improved clinical outcomes in endovascular aortic procedures.

Midterm outcomes of "wide neck" abdominal aortic aneurysm after open or endovascular repair in two European centers: a propensity score matching analysis

BACKGROUND

The aim of this study was to compare mid-term clinical and morphological outcomes in patients undergoing open (OR) and endovascular aortic repair (EVAR) with a proximal wide neck abdominal aortic aneurysm (WN-AAA).

METHODS

Between 2009 and 2014 data of all patients undergoing OR at IRCCS San Raffaele Hospital and EVAR at German Aortic Center Hamburg were retrospectively analyzed. Primary endpoints were aneurysm-related mortality at 5 years, reintervention, and overall mortality. Secondary endpoint was proximal neck enlargement. A 1:1 propensity score matching (PSM) was performed. Survival and freedom from AAA-related reintervention were investigated in matched OR and EVAR group by Kaplan-Meier analysis.

RESULTS

Of all OR performed at IRCCS San Raffaele Hospital 70 were found to have a proximal neck >28 mm (mean age: 69.8±7.2 years, 67 [95.71%] male); of all consecutive EVAR performed at German Aortic Center Hamburg, 52 required an endograft size of at least 32 mm (mean age of 73.1±8.7 years, 49 [94.2%] male). After PSM, the study cohort consisted of 30 OR and EVAR. One early mortality was registered in both groups (P=NS). Mid-term freedom from reintervention compared in OR and EVAR, with no statistically significant differences (P=0.979). Eight (15.4%) patients treated with EVAR developed a significant proximal diameter enlargement (≥3 mm) while only 1 (1.4%) patient in the OR group had the same evolution (P<0.01).

CONCLUSIONS

In WN-AAA neck enlargement is observed more frequently in patients undergoing EVAR, but reintervention rate was similar in the 2 groups, demonstrating that both options were safe and effective.

Pararenal Aortic Thrombus in Patients Undergoing Aortic Aneurysm Repair With Chimney Technique

INTRODUCTION

Chimney technique (chimney graft in abdominal aortic aneurysm repair [ChEVAR]) can be used to treat patients with pararenal aortic aneurysm unfit for open surgery and not suitable for custom-made fenestrated endograft. Since almost 1 in 5 patients undergo a reintervention within 3 years, features associated with higher risk of complications need to be investigated to tailor the follow-up schedule to each patient. The aim of our study was to assess the impact of mural thrombus in the pararenal aorta on perioperative and follow-up complications after ChEVAR.

METHODS

All consecutive patients undergoing ChEVAR at our center from 2015 to 2022 were included in this retrospective study. Collected variables included number of target vessels, stent graft size, presence, and severity of mural thrombus in pararenal aorta, which was reported with a scoring system from 0 to 10 based on thrombus type, thickness area, and circumferenceAnalyzed outcomes included perioperative and follow-up complications.

RESULTS

Thirty-one patients underwent ChEVAR during the study period. In 4 patients the indication for ChEVAR was type 1A endoleak after a previous endovascular aneurysm repair (EVAR). The number of target vessels was 1 in 17 patients (55%), 2 in 12 (39%), 3 in 1 (3%), and 4 in 1 (%). The mean mural thrombus score was 5.9. Complications were the following: type 1A endoleak in 4 cases (13%), chimney stent complications in 7 cases (23%) (including partial or total thrombosis, intrastent stenosis, displacement), renal function worsening during follow-up in 8 cases (26%). Overall survival was 90% at 2 years. Patients with severe mural thrombus showed lower freedom from ChEVAR-related complications (28% vs 59% at 2 years, p=0.023).

CONCLUSIONS

The presence of severe pararenal aortic mural thrombus was associated with lower freedom from ChEVAR-related complications in patients undergoing ChEVAR for pararenal aortic aneurysm repair. Further research with a larger number of patients is required to confirm these results.

CLINICAL IMPACT

The analysis of severity of mural thrombus in pararenal aorta, which was reported with a scoring system from 0 to 10 based on thrombus type, thickness area and circumference, can be useful and can be represent an important predictor element for complications in patient submitted to Chimney tecnique; in fact the presence of severe pararenal aortic mural thrombus was associated with lower freedom from ChEVAR-related complications in patients undergoing ChEVAR for pararenal aortic aneurysm repair. Then, in patient with pararenal aortic aneurysm, a preoperative evaluation could be focused on severity of mural thrombus to minimize the complications in ChEVAR tecnique or to change the surgical strategy.

Shortest Apposition Length at the First Postoperative Computed Tomography Angiography Identifies Patients at Risk for Developing a Late Type Ia Endoleak After Endovascular Aneurysm Repair

PURPOSE

Imaging surveillance following endovascular aneurysm repair (EVAR) is strictly recommended. This study investigates the value of endograft apposition and position relative to the aortic neck on the first postoperative computed tomography angiography (CTA) in determining patients at risk for a late type Ia endoleak (T1aEL).

MATERIALS AND METHODS

Patients with a T1aEL after the first postoperative CTA were selected from a consecutive database and matched with uncomplicated controls. Endograft apposition and position, including the shortest apposition length (SAL), were determined on the first postoperative CTA. The SAL is the shortest distance between the proximal endograft fabric and the first slice where circumferential apposition with the aortic wall is lost. Differences in endograft apposition at the first postoperative CTA were compared between groups. Logistic regression analysis identified independent predictors for late T1aEL.

RESULTS

A total of 32 patients with a late T1aEL were included and matched with 32 uncomplicated controls. Median follow-up after primary EVAR was 62.0 (interquartile range [IQR]: 36.8, 83.5) months in the T1aEL group compared with 47.5 (IQR: 34.0, 79.3) months in the control group; p=0.265. Median preoperative neck diameter was significantly larger in the T1aEL group than in the control group (26.6 [IQR: 24.9, 29.6] mm versus 23.4 [IQR: 22.5, 25.3] mm); p<0.001. Patients in the T1aEL group had a median SAL of 11.6 (IQR: 4.3, 20.5) mm compared with 20.7 (IQR: 13.1, 24.9) mm in the control group; p=0.002. SAL <10mm on the first postoperative CTA (odds ratio [OR]: 9.63, 95% confidence interval [CI]: 1.60-57.99) and larger neck diameter (OR: 1.80, 95% CI: 1.26-2.57) were independent predictors for developing a late T1aEL.

CONCLUSION

Preoperative neck diameter and SAL on the first postoperative CTA following EVAR are important predictors for the development of a late T1aEL. Patients with a SAL of <10mm had a significantly higher risk of developing a late T1aEL. Future research should determine whether these patients would benefit from reintervention before an actual T1aEL is present.

CLINICAL IMPACT

Understanding the mechanisms of endovascular aneurysm repair failure is essential to further enhance clinical outcomes. Adequate proximal sealing is necessary to foster freedom from type 1a endoleak. This study demonstrates that the shortest apposition length (SAL) at the first postoperative computed tomography angiography (CTA) is able to identify patients at risk for a late type 1a endoleak. Especially patients with a SAL <10mm are at high risk. Currently, the guidelines advice repeated imaging with CTA in patients with a seal <10mm. Future research should determine whether these patients would benefit from re-intervention before an actual type 1a endoleak is present.

The Ratio Between the Infrarenal and Suprarenal Aortic Diameter Is a Predictor of Durable Proximal Seal After Endovascular Aneurysm Repair

OBJECTIVES

The aim of this study was to assess whether the ratio of the mean infrarenal neck diameter to the suprarenal aortic diameter is a predictor for a durable proximal seal after endovascular aneurysm repair (EVAR).

METHODS

A total of 439 patients who underwent elective EVAR between 2004 and 2018 in a single vascular referral center met our inclusion criteria. Ratios were calculated by dividing the mean infrarenal neck diameter by 4 different suprarenal aortic diameters. Patients who developed a late type 1A endoleak (n=20) or proximal neck dilatation mandating revision (n=8) were compared with the 411 patients without long-term proximal seal complications.

RESULTS

Patients who developed a late type 1A endoleak had more frequently hypertension, a shorter infrarenal neck length, and a larger mean infrarenal neck diameter. The ratio of the mean infrarenal neck diameter to all 4 suprarenal aortic diameters was higher in the late type 1A endoleak group compared with the group without a late type 1A endoleak. Least absolute shrinkage and selection operator (LASSO) logistic regression identified a combination of 6 variables as the best combination to predict a late type 1A endoleak: presence of hypertension, increased mean infrarenal neck diameter, decreased aneurysm neck length, larger ratio of the mean infrarenal neck diameter to the aortic diameter proximal to the superior mesenteric artery (SMA), larger ratio of the mean infrarenal neck diameter to the aortic diameter proximal to the upper renal artery, and increased β-angle. Of these, based on both the univariate area under the curve (AUC) and optimal LASSO model restricted to a single predictor, the ratio of the mean infrarenal neck diameter to the aortic diameter proximal to the SMA (AUC, 0.770; cutoff value, 0.997) was considered the best prognostic variable.

CONCLUSION

The ratio of the mean infrarenal neck diameter to the aortic diameter proximal to the SMA is a good predictor for a late type 1A endoleak. Patients with mean infrarenal neck diameter larger than the diameter proximal to the SMA (ratio >1) are at risk for a late type 1A endoleak.

CLINICAL IMPACT

In this single-center, retrospective cohort study, we found that the ratio of the mean infrarenal neck diameter to the aortic diameter proximal to the SMA is a good predictor for a late type 1A endoleak. We conclude that the suprarenal diameter must be taken into account before assessing endovascular aortic aneurysm repair eligibility. Patients with a ratio >1 may not be the best candidates for a durable result after EVAR and may be better off with fenestrated EVAR or open repair.

Editor's Choice -- European Society for Vascular Surgery (ESVS) 2024 Clinical Practice Guidelines on the Management of Abdominal Aorto-Iliac Artery Aneurysms

OBJECTIVE

The European Society for Vascular Surgery (ESVS) has developed clinical practice guidelines for the care of patients with aneurysms of the abdominal aorta and iliac arteries in succession to the 2011 and 2019 versions, with the aim of assisting physicians and patients in selecting the best management strategy.

METHODS

The guideline is based on scientific evidence completed with expert opinion on the matter. By summarising and evaluating the best available evidence, recommendations for the evaluation and treatment of patients have been formulated. The recommendations are graded according to a modified European Society of Cardiology grading system, where the strength (class) of each recommendation is graded from I to III and the letters A to C mark the level of evidence.

RESULTS

A total of 160 recommendations have been issued on the following topics: Service standards, including surgical volume and training; Epidemiology, diagnosis, and screening; Management of patients with small abdominal aortic aneurysm (AAA), including surveillance, cardiovascular risk reduction, and indication for repair; Elective AAA repair, including operative risk assessment, open and endovascular repair, and early complications; Ruptured and symptomatic AAA, including peri-operative management, such as permissive hypotension and use of aortic occlusion balloon, open and endovascular repair, and early complications, such as abdominal compartment syndrome and colonic ischaemia; Long term outcome and follow up after AAA repair, including graft infection, endoleaks and follow up routines; Management of complex AAA, including open and endovascular repair; Management of iliac artery aneurysm, including indication for repair and open and endovascular repair; and Miscellaneous aortic problems, including mycotic, inflammatory, and saccular aortic aneurysm. In addition, Shared decision making is being addressed, with supporting information for patients, and Unresolved issues are discussed.

CONCLUSION

The ESVS Clinical Practice Guidelines provide the most comprehensive, up to date, and unbiased advice to clinicians and patients on the management of abdominal aorto-iliac artery aneurysms.

Predictive Parameters of Type 1A Endoleak for Elective Endovascular Aortic Repair: A Single-Center Experience

BACKGROUND

One of the most important factors that affects the success of Endovascular Aortic Repair (EVAR) treatment is the morphology of the neck of the aneurysm. Today, EVAR can be performed even in patients who do not meet the Instruction For Use criteria with hostile neck risk factors; thanks to the developing experience and technology. Our aim in this study was to determine risk factors for Type 1a endoleaks in patients who underwent EVAR and predictive factors for Type 1a endoleaks in patients with combinations of these risk factors.

METHODS

Patients who underwent elective EVAR for infrarenal abdominal aortic aneurysm in our medical center between July 2016 and January 2021 were enrolled. Of these 244 patients, 180 patients with documented preoperative and postoperative computed tomographic angiography results and a follow-up of at least 1 year were included in the study. The Mann-Whitney U test and Student's t-test were used to assess the relationship between nominal data and numerical values, and the t-test and Wilcoxon test were used to compare dependent groups. Logistic regression analysis was performed to model risk factors associated with endoleaks.

RESULTS

The results showed that a neck length less than 15 mm increased the development of type 1a endoleak by 10.4 times (P < 0.001). Furthermore, a neck diameter more than 28 mm increased the development of type 1a endoleak by 21.9 times (P = 0.04). A conical neck structure (gradual neck dilation > 2 mm) increased the development of type 1a endoleaks 4.8 times (P = 0.04). The presence of calcification (> 150 Hounsfield Unit and > 2 mm) in the neck increased the risk of type 1a endoleaks fourfold (P = 0.04). Hostile neck parameters were analyzed and patients with only 1 parameter (n = 69) had a 7.2% type 1a endoleak rate, while patients with 2 parameters (n = 15) had 26.6% and patients with more than 2 parameters (n = 11) had 45.5% type 1a endoleak rate.

CONCLUSIONS

Morphologic features of the neck structure of the aneurysm are among the most important parameters that affect the success of EVAR treatment. Alternative treatments should be considered in patients with more than 1 unfavorable neck parameter.

Brazilian Society for Angiology and Vascular Surgery guidelines on abdominal aortic aneurysm

The Brazilian Society of Angiology and Vascular Surgery, through the Guidelines Project, presents new Abdominal Aortic Aneurysm Guidelines, on the subject of care for abdominal aortic aneurysm patients. Its development prioritized descriptive guidelines, using the EMBASE, LILACS, and PubMed databases. References include randomized controlled trials, systematic reviews, meta-analyses, and cohort studies. Quality of evidence was evaluated by a pair of coordinators, aided by the RoB 2 Cochrane tool and the Newcastle Ottawa Scale forms. The subjects include juxtarenal aneurysms, infected aneurysms, and new therapeutic techniques, especially endovascular procedures. The current version of the guidelines include important recommendations for the primary topics involving diagnosis, treatment, and follow-up for abdominal aortic aneurysm patients, providing an objective guide for medical practice, based on scientific evidence and widely available throughout Brazil.

Risk factors of type 1A endoleak following endovascular aortic aneurysm repair

OBJECTIVES

Endovascular repair of infrarenal aortic aneurysms are the treatment of first choice. However, the proximal sealing of endovascular aneurysm repair is the Achilles' heel of the procedure. Insufficient proximal sealing can lead to endoleak type 1A and therefore expansion of the aneurysm sack and subsequent rupture.

METHODS

We performed a retrospective analysis of all consecutive patients with an infrarenal abdominal aneurysm treated with endovascular aneurysm repair. We studied whether demographic and anatomical features were risk factors for endoleak type 1A. Also, the results of different treatment strategies were described.

RESULTS

257 Patients were included in the study, most patients were male. In the multivariate analysis, female gender and infrarenal angulation were the most important risk factors for endoleak type 1A. Endoleak type 1A diagnosed at completion angiography disappeared in 77.8%. The occurrence of endoleak type 1A was associated with a higher risk of aneurysm-related mortality (p = 0.01).

CONCLUSION

Conclusions should be drawn with care, since the number of patients included in this study was small and there was a high incidence of patients lost to follow-up. This study suggests that endovascular aneurysm repair in female patients and patients with severe infrarenal angulation is associated with a higher risk of endoleak type 1A.

Editor's Choice - Endurant Stent Graft in Patients with Challenging Neck Anatomy "One Step Outside Instructions for Use": Early and Midterm Results from the EAGLE Registry

OBJECTIVE

The aim of the Endurant for Challenging Anatomy: Global Experience (EAGLE) registry is to evaluate prospectively the technical and clinical success rate of a stentgraft used in patients with challenging neck anatomy outside the instructions for use (IFU) but within objective anatomical limits.

METHODS

This was a prospective, international, multicentre, observational study. From 1 February 2012 to 1 September 2017, patients with an abdominal aortic aneurysm with a challenging infrarenal neck that were deemed suitable for endovascular aneurysm repair were included prospectively at 23 European centres. Patients were distributed by anatomy into three groups: short neck (SN; infrarenal neck 5 - 10 mm in combination with suprarenal angulation [α] ≤ 45° and infrarenal angulation [β] ≤ 60°); medium neck (MN; infrarenal neck 10 - 15 mm with α ≤ 60° and β 60° - 75° or α 45°- 60° and β ≤ 75°; and long angulated neck (LN; infrarenal neck ≥ 15 mm with α ≤ 75° and β 75°- 90° or α 60°- 75° and β ≤ 90°. All computed tomography scans were reviewed by an independent core laboratory. Primary outcomes were technical and clinical success. Secondary endpoints were peri-operative major adverse events, all cause mortality, aneurysm related mortality, endoleaks, migration, and secondary intervention.

RESULTS

One hundred and fifty patients (81.3% male) were included (SN = 55, MN = 16, LN = 79). The median follow up was 36 ± 12.6 months. In the overall cohort, the technical success rate was 93.3%. Estimated freedom from aneurysm related death was 97.3% at three years. Freedom from secondary interventions was 84.7% at three years. Estimated clinical success was 96.0%, 90.8%, and 83.2% at 30 days, one year, and three years, respectively. Estimated freedom from all cause mortality, late type IA endoleak, and migration at three years was 75.1%, 93.7%, and 99.3%, respectively.

CONCLUSION

The early and midterm results of the EAGLE registry show that endovascular repair with the Endurant stentgraft in selected patients with challenging infrarenal neck anatomy yields results in line with large "real world" registries. Long term results are awaited for more definitive conclusions.

Pre-operative Aortic Neck Characteristics and Post-operative Sealing Zone as Predictors of Type 1a Endoleak and Migration After Endovascular Aneurysm Repair: A Systematic Review and Meta-Analysis

OBJECTIVE

Establishing the predictive value of neck characteristics and real achieved sealing zone is essential to foster risk stratified procedure selection and imaging surveillance. This systematic review provides an overview of pre-operative aortic neck characteristics and post-operative real achieved sealing zone and their respective risk of type 1a endoleak and migration after endovascular aneurysm repair (EVAR).

METHODS

In agreement with PRISMA guidelines, MEDLINE, Embase, and Cochrane CENTRAL were searched. Data on neck characteristics, sealing zone, and EVAR outcome were extracted. Meta-analyses were performed to investigate the effect of neck diameter, angulation, and shape on type 1a endoleak (total, early ≤ 90 days, and late > 90 days) and migration in patients who underwent EVAR. A qualitative summary was also provided.

RESULTS

Thirty-three studies were included. Patients with a larger neck diameter had an increased risk of total type 1a endoleak (nine studies: OR 3.32, 95% CI 2.38 - 4.63), early type 1a endoleak (six studies: OR 2.64, 95% CI 1.27 - 5.48), late type 1a endoleak (six studies: OR 3.26, 95% CI 2.12 - 5.03), and migration (seven studies: OR 2.88, 95% CI 1.32 - 6.26). An angulated neck increased the risk of total type 1a endoleak (seven studies: OR 4.27, 95% CI 1.55 - 11.78) and late type 1a endoleak (seven studies: OR 5.56, 95% CI 2.19 - 14.13). Neck shape was not associated with type 1a endoleak. Neck length and real achieved sealing zone on post-EVAR computed tomography were identified as risk factors for type 1a endoleak and migration through qualitative summary.

CONCLUSION

There seems to be some consistent evidence that aortic neck diameter, angulation, and length are associated with the development of type 1a endoleak or migration. Real achieved sealing zone might be an important addition during follow up. However, a small number of studies, with serious limitations, could be included, and there was considerable variability in reporting patients and outcomes. A proposal for standardisation of aortic and EVAR data in future studies is provided.

Predictive value of elliptical neck parameters and oversizing ratio for type Ia endoleaks after endovascular aneurysm repair

OBJECTIVE

To assess the predictive value of elliptical geometric parameters regarding type IA endoleak (T1AEL) after endovascular aneurysm repair (EVAR) and investigate optimal range of oversizing ratio (OSR) in patients with elliptical aneurysmal neck.

METHODS

In this propensity-score matched case-control study, case patients were those diagnosed with T1AEL, control patients were those who did not have T1AEL after EVAR in the same period from 2012 to 2018. Geometric and oversizing parameters were compared based on both 2D and 3D measurement. Net reclassification improvement (NRI) was used to measure prediction increment of elliptical model (major axis OSR, neck length and severe neck angulation (SNA)) compared to conventional model (OSR 2D, neck length and SNA).

RESULTS

Nineteen case patients and 111 control patients were included. The median OSR 2D of T1AEL patients were 17% (15%-22%), but the median major axis OSR were only 7% (5%-12%). Among geometric parameters, axis difference had the highest area under the curve (AUC) of 0.74 (95%CI 0.63-0.84) in predicting T1AEL. As for elliptical oversizing parameters, major axis OSR had an AUC of 0.89 (95%CI 0.78-0.97) with a cut-off value of 13%. Elliptical model had higher discriminating ability in T1AEL compared to conventional model (AUC 0.91 vs 0.86, P=0.045), with improved reclassification ability (NRI 27.93%, 95% CI 19.22%-36.64%, P<0.0001).

CONCLUSION

Elliptical aneurysmal neck, assessed by axis difference, is associated with an increased risk of T1AEL. Calculation of oversizing based on major axis for at least 13% can significantly reduce the risk of T1AEL in patients with elliptical aneurysmal neck.

Hybrid room: Does it offer better accuracy in the proximal deployment of infrarenal aortic endograft?

PURPOSE

This work aims to evaluate the impact of hybrid rooms and their advanced tools on the accuracy of proximal deployment of infrarenal bifurcated endograft (EVAR).

METHODS

A retrospective single centre analysis was conducted between January 2015 and March 2019 including consecutive patients that underwent EVAR. Groups were defined whether the procedure was performed in a hybrid operating room (HOR group) or using a mobile 2D fluoroscopic imaging system (non-HOR group). The accuracy of the proximal deployment was estimated by the distance (mm) between the bottom of the lowest renal artery (LwRA) origin and the endograft radiopaque markers parallax (LwRA/EDG distance) after curvilinear reconstruction. The impact of HOR on the LwRA/EDG distance was investigated using a multiple linear regression model. A composite "proximal neck"-related complications event was studied (Cox models).

RESULTS

Overall, 93 patients (87 %male, median age 73 years) were included with 49 in the HOR group and 44 in the non-HOR group. Preoperative CTA analysis of the proximal neck exhibited similar median length, but different median aortic diameter (p=0.012) and median beta angulation (p=0.027) between groups. The median LwRA/EDG distance was shorter in the HOR group (multivariate model, p=0.022). No difference in "proximal neck"-related complications was evidenced between the HOR and non-HOR groups (univariate analysis, p=0.620). Median follow-up time was respectively 25 [14-28] and 36 months [23-44] in the HOR group and in the non-HOR group (p<0.001).

CONCLUSION

HOR offer more accurate proximal deployment of infrarenal endografts, with however no difference in "proximal neck"-related complications between groups.

New Morphological Factor for Predicting Late Proximal Type I Endoleak after Endovascular Aneurysm Repair

BACKGROUND

Although we have witnessed several cases of late proximal type I endoleak (T1AEL) after endovascular aneurysm repair (EVAR), most patients did not have "hostile neck" preoperatively. We hypothesized that the distance between the lowest renal artery and the neck angulation point and neck length are the 2 most important factors for maintaining long-term proximal sealing. This study evaluated "neck hostility," which is the product of the distance to the angulation point and the neck length, as a preoperative morphological risk factor for the development of late T1AEL after EVAR.

METHODS

A retrospective review of a prospectively assembled database was performed for all patients who had undergone EVAR at a single institution from June 2007 to May 2017. Patient demographics and preoperative imaging data were collected, and Cox regression analysis was performed to identify the risk factors for late T1AEL.

RESULTS

Of the 655 patients who underwent EVAR during the study period, 115 were excluded due to complex EVAR (n = 14), primary indications for iliac aneurysms (n = 86), primary T1AEL (n = 3), or other reasons (n = 15). Of the remaining 537 patients, twelve patients (2.2%) developed late T1AEL a median of 3.2 (interquartile range [IQR]; 3.0, 5.4) years after EVAR. Receiver operating characteristic (ROC) curve analysis revealed a neck hostility cutoff value of 8. Cox regression analysis revealed that a neck hostility value ≤8 and conical neck anatomy were risk factors for the development of late T1AEL after EVAR. Well-known hostile neck factors such as short neck, severe angulated neck, and severe calcification/thrombus in the proximal neck were not significantly different.

CONCLUSIONS

The present study demonstrated a correlation between late T1AEL and the product of the angulation distance and the neck length. This factor may be useful for predicting poor late proximal outcomes after EVAR.

Fenestrated endovascular repair with large device diameters (34- to 36-mm) is associated with type 1 and 3 endoleak and reintervention

OBJECTIVES

 Patients with abdominal aortic aneurysms undergoing EVAR with larger device diameters (34- to 36-mm) have worse outcomes due to proximal fixation failure and need for reintervention. We examine outcomes relating to standard fenestrated repair (FEVAR) with larger device diameters, and investigate whether a similar relationship exists.

MATERIAL AND METHODS

 Retrospective review of a prospectively maintained, single institution database of patients treated with the Cook ZFEN device between 2012-2017. Outcomes were stratified by device diameter into normal-diameter (ND,≤ 32 mm) and large-diameter (LD,34-36 mm). Primary endpoints were need for reintervention and composite type I/III endoleak.

RESULTS

 100 consecutive patients treated were identified for inclusion. Overall mean age was 73.6 years and mean aortic diameter was 59.1 mm. Mean follow-up was 22 months. A total of 26 (26%) patients were treated with LD devices. Number of target vessels per patient was 2.8 in both groups. Infrarenal neck length and diameter were significantly different in the LD and ND patients, respectively (2.6 mm vs 4.7 mm (P<.01) and 30.1 mm vs 23.4 mm (P<.01)). Percent graft oversizing was lower in the LD cohort (19% vs 24%; P=.006). No difference was seen in overall mortality at 30-days (0% vs 2%; P=.4) or at latest follow up (6% vs 14%; P=.6). Reinterventions were not significantly different at 30 days, but were significantly higher over the follow-up period in the LD cohort (46.2 vs. 17.6%; P=.002). LD diameter was associated with reintervention on univariate (HR 1.19, 95% CI 1.04-1.37), but not multivariate analysis. The composite endpoint of type I/III endoleak was higher in the LD cohort (15.4% vs. 2.7%; P=.004).

CONCLUSION

 FEVAR requiring 34- or 36-mm device diameters is associated with an increased risk of composite type I/III endoleak and reintervention. Patients undergoing fenestrated repair requiring LD devices should be closely monitored, with consideration for proximal or open repair.

Initial Clinical Experience With a New Conformable Abdominal Aortic Endograft: Aortic Neck Coverage and Curvature Analysis in Challenging Aortic Necks

OBJECTIVES

Aim of this work was to investigate precision of deployment and conformability of a new generation GORE EXCLUDER Conformable Endoprosthesis with active control system (CEXC Device, W.L. Gore and Associates, Flagstaff, AZ, USA) by analyzing aortic neck coverage and curvature.

METHODS

All consecutive elective patients affected by abdominal aortic aneurysm or aortoiliac aneurysm treated at our institution between November 2018 and June 2019 with the new CEXC Device were enrolled. Validated software was adopted to determine the available apposition surface area into the aortic neck, apposition of the endograft to the aortic wall, shortest apposition length (SAL), shortest distance between the endograft fabric and the lowest renal arteries (SFD) and between the endograft fabric and the contralateral renal artery (CFD). Pointwise centerline curvature was also computed.

RESULTS

Twelve patients (10 men, median age 78 years (71.75, 81.0)) with available pre- and postoperative computed tomography angiography (CTA) were included. Technical success was obtained in all the cases. Preoperative median length of the proximal aortic neck was 16.1 mm (10.7, 21.7) and suprarenal (α) and infrarenal (β) neck angulation were, respectively, 28.9° (15.7°, 47.5°) and 75.0° (66.9°, 81.4°). Postoperative median apposition surface coverage was 79% (69.25%, 90.75%) of the available apposition surface. SFD and CFD were 1.5 mm (0.75, 5.25) and 7 mm (4.5, 21.5), respectively. Average curvature over the infrarenal aorta decreased from 25 m^-1 (21.75, 29.0) to 22.5 m^-1 (18.75, 24.5) postoperatively (p=0.02). Maximum curvature did not decrease significantly from 64.5 m^-1 (54.25, 92.0) to 62 m^-1 (41.75, 71.5) (p=0.1).

CONCLUSIONS

Our early experience showed that deployment of the CEXC Device is safe and effective for patients with challenging proximal aortic necks. Absence of significant changes between pre- and postoperative proximal aortic neck angulations and curvature confirms the high conformability of this endograft.

Remodeling of Abdominal Aortic Angulation and Curvature After Endovascular Aneurysm Repair in Patients With vs Without Late Type Ia Endoleak or Endograft Migration

PURPOSE

To investigate aortic remodeling of the supra- and infrarenal aorta from preoperative to 1 month and midterm follow-up after endovascular aneurysm repair (EVAR) by analyzing changes in angulation and curvature in patients with vs without late type Ia endoleak or device migration.

MATERIALS AND METHODS

From a multicenter database, 35 patients (mean age 76±5 years; 31 men) were identified with late (>1 year) type Ia endoleak or endograft migration (≥10 mm) and defined as the complication group. The control group consisted of 53 patients (mean age 75±7 years; 48 men) with >1-year computed tomography angiography (CTA) follow-up and no evidence of endoleaks. Suprarenal and infrarenal angles were measured on centerline reconstructions of the preoperative, 1-month, and midterm CTA scans. The value and location relative to baseline of maximum suprarenal and infrarenal curvature were determined semiautomatically using dedicated software. Changes were determined at 1 month compared with the preoperative CTA and at midterm compared with 1 month.

RESULTS

Preoperative suprarenal angulation was significantly greater in the complication group compared to the controls (34°±18° vs 24°±17°, p=0.008). It decreased significantly at 1 month in the complication group (29°±16°, p=0.011) and at midterm follow-up in the controls (20°±19°, p<0.001). Preoperative infrarenal angulation was not significantly different (57°±15° vs 49°±24°, p=0.114). This measurement increased significantly through midterm follow-up in the complication group (63°±23°, p<0.001) but remained stable in the controls (46°±22°). Preoperative suprarenal curvature was not significantly different (38±22 m^-1 vs 29±25 m^-1, p=0.115). This variable increased significantly through midterm follow-up in the complication group (44±22 m^-1) but remained constant in the controls (28±22 m^-1). Preoperative infrarenal curvature was significantly greater in the complication group (77±29 m^-1 vs 65±28 m^-1, p=0.047) and decreased significantly in both groups during midterm follow-up (50±17 m^-1 vs 41±19 m^-1 p=0.033). The location of the maximum curvature with regard to baseline shifted significantly distally in the complication group (54±43 to 72±41 mm, p<0.001), while it remained stable in the controls (46±33 to 48±31 mm).

CONCLUSION

At midterm follow-up, significant differences in supra- and infrarenal angulation and curvature were observed between patients with vs without type Ia endoleak or migration. The location of the maximum curvature shifted distally in patients with complications. The aortic morphology is more stable during midterm follow-up in the patients without endoleaks.

Comparison of Outcomes Following EVAR Based on Aneurysm Diameter and Volume and Their Postoperative Variations

PURPOSE

to evaluate the impact of bi- and 3-dimensional preoperative aortic morphological features and their immediate postoperative variations on the outcome of abdominal aortic aneurysms (AAA) treated by endovascular exclusion with standard devices (EVAR).

MATERIALS AND METHODS

Double centre retrospective analysis of prospectively collected registry data of EVAR patients. For all patients, preoperative and 30-day computed tomographic angiography images (CTA) were reviewed. Preoperative maximum AAA diameter >59 mm and volume >159 cm³, and any 30-day postoperative increasing at CTA, were considered as potentially influencing the outcome. The outcome measures were: primary technical success; 30-day, 1-year, and mean follow-up reintervention, all-cause and AAA-related mortality rates, and also endoleak-related reinterventions.

RESULTS

Three hundred and thrity-three patients were enrolled. Mean preoperative and 30-day AAA diameter and volume were 50.4 mm ± 11.8 vs. 49.1 mm ± 12.1, and 112.9 cm3 ± 79.5 vs. 112.1 cm3 ± 80.5, respectively. Primary technical success was achieved in all cases. At 34.9 months follow-up, cumulative reintervention rate was 12.0%, mortality rates 7.2%, without AAA-related deaths. Endoleak-related reintervention rate was 7.5%. At uni- and multi-variate analysis, preoperative AAA diameter >59 mm, and AAA volume >159 cm³ were significantly associated to reintervention (P = 0.012; P = 0.002), and reintervention and death (P = 0.002; P = 0.001) during follow-up. Additionally, any increase in postoperative AAA diameter or volume was significantly associated with reintervention (P = 0.001, P = 0.001) and reintervention and death (P = 0.006, P = 0.001). Endoleak-related reintervention were also significantly associated with all of the analysed morphological parameters (P = 0.019, P = 0.005, P = 0.005, and P = 0.002, respectively).

CONCLUSIONS

Patients with larger baseline AAA size and volume as well as unfavourable early remodelling of the sac are associated to worse long-term EVAR outcome.

Secondary Interventions and Long-term Follow-up after Endovascular Abdominal Aortic Aneurysm Repair

BACKGROUND

Early morbidity and mortality are low after endovascular abdominal aneurysm repair (EVAR), but secondary interventions and late complications are common. The aim of the present multicenter cohort study is to detail the frequency and indication for interventions after EVAR and the impact on long-term survival.

METHODS

A retrospective multicenter cohort study of secondary interventions after elective EVAR for an infrarenal abdominal aortic aneurysm was conducted. Consecutive patients (n = 349) undergoing EVAR between January 2007 and January 2012 were analyzed, with long-term follow-up until December 2018. Those requiring intervention were classified in accordance with the indications and specific nature of the intervention and treatment. The primary study end point was overall survival classified for patients with and without intervention. Kaplan-Meier analysis was used to estimate overall survival for those who did and who did not undergo secondary interventions. Univariable and multivariable Cox regression were performed to identify independent variables associated with mortality.

RESULTS

Some 56 patients (16%) underwent 72 secondary interventions after EVAR during a median (interquartile range) follow-up period of 53.2 months (60.1). Some 45 patients (80.4%) underwent one intervention. Indications for intervention included mainly endograft kinking/outflow obstruction and type II endoleak. An endovascular technique was used in 40.3% of interventions. Median time to secondary intervention was 24.1 months. In 93 patients with abnormalities on imaging, no intervention was performed mainly because the abnormality had disappeared on follow-up imaging (43%). Kaplan-Meier curves showed no difference in survival for patients with and without secondary interventions (P = 0.153). Age (hazard ratio [HR]: 1.089, 95% confidence interval [CI]: 1.063-1.116), ASA classification (ASA III, IV HR: 1.517, 95% CI: 1.056-2.178) were significantly related to mortality.

CONCLUSIONS

Secondary intervention rates are still considerable after EVAR. Endograft kinking/outflow obstruction and endoleak type II are the most common indications for a secondary intervention. Secondary interventions did not adversely affect long-term overall survival after EVAR.

Total Luminal Volume Predicts Risk after Endovascular Aneurysm Repair

OBJECTIVE

Large aneurysm diameter represents a well known predictor of late complications after endovascular aneurysm repair (EVAR). However, the role of the thrombus free lumen inside the abdominal aortic aneurysm (AAA) sac is not clear. It was hypothesised that greater luminal volume represents a relevant risk factor for late complications after EVAR.

METHODS

A retrospective cohort analysis was performed including all patients undergoing EVAR from 2005 to 2016 at a tertiary referral institution. Pre-operative AAA lumen volume was measured in centre lumen line reconstructions and patients were stratified into quartiles according to luminal volume. The primary endpoint was freedom from AAA related complications. Secondary endpoints were freedom from neck events (type 1A endoleak, migration >5 mm or any pre-emptive neck related intervention), iliac related events (type 1B endoleak or pre-emptive iliac related intervention), and overall survival.

RESULTS

Four hundred and four patients were included: 101 in the first quartile (Q1; <61 cm³). Patients with higher luminal volumes had wider, shorter, and more angulated proximal necks. There were more ruptured AAAs, more aorto-uni-iliac implanted devices and patients outside neck instructions for use in the 4th quartile. Five year freedom from AAA related complications was 79%, 66%, 58% and 56%, respectively (p = .007). At five years, freedom from neck related events was 86%, 84%, 73%, and 71%, respectively, for the four groups (p = .009), and freedom from iliac related events was 96%, 91%, 88%, and 88%, respectively (p = .335). On multivariable analysis, luminal volume was an independent predictor of late complications (Q4 vs. Q1 - hazard ratio: 1.91, 95% confidence interval 1.01-3.6, p = .046). Overall survival at five years was not affected by lumen volume (p = .75).

CONCLUSION

AAA luminal volume represents an important risk factor for AAA related complications. This information may be considered when deciding tailoring surveillance protocols after EVAR. However, larger studies are needed to validate this hypothesis.

Reverse slider technique using the Endurant stent graft for accurate proximal sealing in hostile neck endovascular aneurysm repair

This report introduces the reverse slider technique to obtain proximal sealing effectively in endovascular aneurysm repair in short or angulated necks. It is the deployment process of the stent graft main body by repeatedly rotating and reversing the external slider with slight loosening of the suprarenal stent. This method helps obtain accurate placement of the proximal edge and effective sealing on the greater curvature side even in short and angulated necks. It is an effective method of extending the proximal sealing zone. It is gained by changing the deployment process with the Endurant stent graft (Medtronic, Santa Rosa, Calif) as an existing popular device.

Stent-graft surface movement after endovascular aneurysm repair: baseline parameters for prediction, and association with migration and stent-graft-related endoleaks

OBJECTIVES

To evaluate the influence of baseline parameters on the occurrence of stent-graft surface movement after endovascular aneurysm repair (EVAR) and to investigate its association with migration and stent-graft-related endoleaks (srEL).

METHODS

In this retrospective, cross-sectional study, three-dimensional surface models of the stent-graft, delimited by landmarks using custom-built software, were derived from the pre-discharge and last follow-up computed tomography angiography (CTA). Stent-graft surface movement in the proximal anchoring zone between these examinations was considered significant at a threshold of 9 mm. The Cox proportional hazards model was used to determine baseline variables associated with the occurrence of stent-graft surface movement. The association between migration and srEL with stent-graft surface movement was tested with the chi-square and the Fisher exact test, respectively.

RESULTS

Stent-graft surface movement was observed in 54 (28.9%) of 187 patients. Multivariate analysis revealed that age ([HR] 1.05; p = 0.017), proximal neck diameter ([HR] 5.07; p < 0.001), infrarenal aortic neck angulation ([HR] 1.02, p = 0.002), and proximal neck length ([HR] 0.62, p < 0.001) were significantly associated with the occurrence of stent-graft surface movement. Migration and srEL occurred in 17 (31.5%) and 5 (9.3%) patients, with and 11 (8.3%) and 2 (1.5%) without stent-graft surface movement (p < 0.001, p = 0.022).

CONCLUSIONS

Age, neck diameter, infrarenal neck angulation, and proximal neck length were significantly associated with the occurrence of stent-graft surface movement. Apart from possible use of adjunctive sealing systems, concerned patients may benefit from regular CTA surveillance, enabling timely diagnosis of subtle changes of stent-graft position.

KEY POINTS

• Stent-graft surface movement, demonstrating subtle, three-dimensional changes in stent-graft position in the proximal anchoring zone, can be derived from CTA examinations. • Age, proximal neck diameter, and infrarenal neck angulation were significantly associated with an increased incidence of stent-graft surface movement. Stent-graft surface movement is significantly more frequent in patients with stent-graft migration and stent-graft-related endoleaks. • Consideration of risk factors for stent-graft surface movement may help to identify patients who might benefit from regular CTA surveillance and timely diagnosis of subtle changes of stent-graft position, enabling re-interventions to prevent migration and srEL.

Reporting of Complications and Mortality in Relation to Risk Communication in Patients with an Abdominal Aortic Aneurysm: A Systematic Review

OBJECTIVES

High-quality reporting of surgical risks is necessary for evidence-based risk communication in clinical practice. Risk communication is defined as the process of discussing benefits and harms of treatment options with patients. This review addressed the current quality of reporting of complications and mortality in publications on abdominal aortic aneurysm treatment, with a focus on items relevant to risk communication.

DESIGN

A systematic review.

MATERIALS

Randomised clinical trials, comparative observational studies and registries from 2010 onwards were eligible if they reported complications and/or mortality in patients with an asymptomatic abdominal aortic aneurysms who received primary treatment.

METHODS

Quality of reporting was assessed by scoring items relevant to risk communication from the reporting standards of the Society for Vascular Surgery (SVS) and the Consolidated Standards of Reporting Trials (CONSORT) statement. Screening, quality assessment and data extraction were independently undertaken by two authors.

RESULTS

Forty-seven publications were included. Nine of 47 publications (19%) provided no definition of complications. In 14 of 47 publications (30%), it was unclear whether the number of adverse events or the number of patients with adverse events were presented. Absolute risk differences were provided in 1 of 32 publications (3.1%) that compared complications between two treatment options. Forty-six of 47 publications reported mortality, of which 42 reported overall mortality rates (91%). Absolute risk differences were given in 2 of the 31 publications (6.5%) that compared mortality between two treatment options.

CONCLUSIONS

The quality of reporting of complications and mortality following primary abdominal aortic aneurysm treatment varied considerably. Better adherence to the SVS reporting standards and the CONSORT statement, as well as stating absolute risk differences may improve the quality of reporting and facilitate evidence-based risk communication.

Contrast-enhanced ultrasound and/or colour duplex ultrasound for surveillance after endovascular abdominal aortic aneurysm repair: a systematic review and economic evaluation

BACKGROUND

Endovascular abdominal aortic aneurysm repair (EVAR) of abdominal aortic aneurysm (AAA) is less invasive than open surgery, but may be associated with important complications. Patients receiving EVAR require long-term surveillance to detect abnormalities and direct treatments. Computed tomography angiography (CTA) has been the most common imaging modality adopted for EVAR surveillance, but it is associated with repeated radiation exposure and the risk of contrast-related nephropathy. Colour duplex ultrasound (CDU) and, more recently, contrast-enhanced ultrasound (CEU) have been suggested as possible, safer, alternatives to CTA.

OBJECTIVES

To assess the clinical effectiveness and cost-effectiveness of imaging strategies, using either CDU or CEU alone or in conjunction with plain radiography, compared with CTA for EVAR surveillance.

DATA SOURCES

Major electronic databases were searched, including MEDLINE, EMBASE, Science Citation Index, Scopus' Articles-in-Press, Cochrane Central Register of Controlled Trials (CENTRAL), Database of Abstracts of Reviews of Effects (DARE) and NHS Economic Evaluation Database from 1996 onwards. We also searched for relevant ongoing studies and conference proceedings. The final searches were undertaken in September 2016.

METHODS

We conducted a systematic review of randomised controlled trials and cohort studies of patients with AAAs who were receiving surveillance using CTA, CDU and CEU with or without plain radiography. Three reviewers were involved in the study selection, data extraction and risk-of-bias assessment. We developed a Markov model based on five surveillance strategies: (1) annual CTA; (2) annual CDU; (3) annual CEU; (4) CDU together with CTA at 1 year, followed by CDU on an annual basis; and (5) CEU together with CTA at 1 year, followed by CEU on an annual basis. All of these strategies also considered plain radiography on an annual basis.

RESULTS

We identified two non-randomised comparative studies and 25 cohort studies of interventions, and nine systematic reviews of diagnostic accuracy. Overall, the proportion of patients who required reintervention ranged from 1.1% (mean follow-up of 24 months) to 23.8% (mean follow-up of 32 months). Reintervention was mainly required for patients with thrombosis and types I-III endoleaks. All-cause mortality ranged from 2.7% (mean follow-up of 24 months) to 42% (mean follow-up of 54.8 months). Aneurysm-related mortality occurred in < 1% of the participants. Strategies based on early and mid-term CTA and/or CDU and long-term CDU surveillance were broadly comparable with those based on a combination of CTA and CDU throughout the follow-up period in terms of clinical complications, reinterventions and mortality. The economic evaluation showed that a CDU-based strategy generated lower expected costs and higher quality-adjusted life-year (QALYs) than a CTA-based strategy and has a 63% probability of being cost-effective at a £30,000 willingness-to-pay-per-QALY threshold. A CEU-based strategy generated more QALYs, but at higher costs, and became cost-effective only for high-risk patient groups.

LIMITATIONS

Most studies were rated as being at a high or moderate risk of bias. No studies compared CDU with CEU. Substantial clinical heterogeneity precluded a formal synthesis of results. The economic model was hindered by a lack of suitable data.

CONCLUSIONS

Current surveillance practice is very heterogeneous. CDU may be a safe and cost-effective alternative to CTA, with CTA being reserved for abnormal/inconclusive CDU cases.

FUTURE WORK

Research is needed to validate the safety of modified, more-targeted surveillance protocols based on the use of CDU and CEU. The role of radiography for surveillance after EVAR requires clarification.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016036475.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Recent Advances and Mid-to-Long Term Results of Endovascular Aneurysm Repair for Abdominal Aortic Aneurysms

Endovascular aneurysm repair (EVAR) has become the standard therapy alongside open surgery repair (OSR) for abdominal aortic aneurysm (AAA) and it is rapidly becoming prevalent. There has been substantial technical progress with respect to EVAR since its introduction. Technical contrivance can be used to manage even inappropriate EVAR cases, including those involving a hostile neck, deficient access route, or aneurysm rupture. However, there are some controversies over reinterventions in relation to long-term outcomes. Although a long-term result has not yet been analyzed in Japan a randomized controlled trial (RCT) held in the West reported that OSR is superior to EVAR for avoiding reinterventions and aneurysm-related death. The RCT involved the use of older devices and proceeded in a different way from the present study; therefore, different results may be obtained for Japanese EVAR outcomes. However, this Western RCT result should be considered as an important warning. Type II endoleak also must be managed in order to improve long term outcomes of EVAR. Efforts to improve both technical methodology and long-term outcomes are necessary to ensure EVAR as a minimally invasive therapy for patients with AAA. (This is a translation of Jpn J Vasc Surg 2018; 27: 405-411.).

Chimney Endovascular Aneurysm Repair Using Endurant Stent-Grafts With Bare Balloon-Expandable Stents for Patients With Juxtarenal Aortic Aneurysms

PURPOSE

To evaluate the advantages of chimney endovascular aneurysm repair (chEVAR) using an Endurant stent-graft with uncovered balloon-expandable stents (BES) for patients with juxtarenal aortic aneurysms.

MATERIALS AND METHODS

Twenty-two patients (mean age 78.5±9.0 years; 13 men) who underwent chEVAR using Endurant and uncovered BES between January 2014 and December 2017 were analyzed retrospectively. The maximum aneurysm diameter was 59.1±11.9 mm, and the proximal neck length was 5.2±2.9 mm. Of the 22 cases, 9 (40%) involved proximal neck angulation and 9 (40%) had a conical neck. Single and double chimneys were performed using BES in 19 and 3 cases, respectively. In 2 cases, an additional self-expanding covered stent was used inside the uncovered BES.

RESULTS

The technical success was 91% (20/22) as 2 (9%) cases showed minor type Ia endoleak. No postoperative systemic complications or acute renal dysfunction (Acute Kidney Injury Network classification stage 2 or higher) were observed. The mean radiologic observation period was 16.1±9.6 months, and no aneurysm expansion (>5 mm) was observed during this time. The mean maximum aneurysm diameter decreased to 52.9±10.2 mm (p<0.001 vs preoperative), with an individual mean sac regression of 6.2±5.9 mm. Overall primary chimney stent patency was 100%. One of the 2 cases of intraoperative type Ia endoleak resolved at the 6-month imaging, and no new type Ia endoleaks developed in any cases at follow-up. No additional treatment- or aneurysm-related events were observed.

CONCLUSION

Short-term outcomes of chEVAR using Endurant with uncovered BES have been favorable when covered stents were unavailable, and it can be useful for high-risk patients with juxtarenal aortic aneurysms.

Morphology-Related Limitations of Endovascular Aneurysm Repair Applicability in the Treatment of Abdominal Aortic Aneurysm in West-Central Poland

BACKGROUND

Morphology is one of the most important factors influencing the long-term durability of endovascular repair of an infrarenal abdominal aortic aneurysm (AAA). The knowledge of morphological characteristics of AAA that may differ in various populations seems to be important for further development of a technology of endovascular repair as well as for planning of treatment strategies. To analyze the current applicability of endovascular aneurysm repair (EVAR) in patients with an infrarenal AAA with an indication for elective treatment in west-central Poland.

METHODS

Computed tomography angiograms of 100 consecutive patients with infrarenal AAA deemed to require treatment were analyzed with an OsiriX DICOM viewer in 3D-multiplanar reconstruction mode. Proximal neck diameter, length, angulation, shape, the presence of thrombus and calcification, distal neck diameter, and morphology of the iliac arteries were determined. Three sets of morphological criteria were established. The optimal criteria consisted of a nonconical proximal neck without moderate or severe calcification or thrombus, with a diameter of 18-28 mm, length of ≥15 mm, and β angulation of <60%; a distal neck with a diameter of ≥20 mm; a landing zone in the common iliac arteries (CIAs) with a length of ≥10 mm and diameter of ≤20 mm; and external iliac arteries with diameters of ≥7 mm. The suboptimal criteria included proximal neck diameters of 18-32 mm, neck lengths ≥10 mm, infrarenal neck angulations of up to 75°, and CIA diameters of up to 25 mm. Finally, the extended suboptimal criteria included proximal neck diameters of 16-34 mm and infrarenal neck angulations ≤90°, without limits in the maximal diameter of the CIAs.

RESULTS

The median maximum aneurysm diameter was 61 mm. The optimal, suboptimal, and extended suboptimal criteria were met by 23%, 32%, and 53% of patients, respectively. The most common deviations were wide, conical, and angulated proximal necks and aneurysmal iliac arteries.

CONCLUSIONS

The majority of patients with AAA deemed to be candidates for elective repair do not meet the most favorable criteria for EVAR. Availability of better endovascular solutions for conical, angulated, and wide necks and aneurysmal iliac arteries would likely expand EVAR applicability. Open repair remains a valid option.

Comparative study of clinical outcome of endovascular aortic aneurysms repair in large diameter aortic necks (>31 mm) versus smaller necks

BACKGROUND

This study compares short-term (30 days) and intermediate term (3 years) clinical outcomes in patients with large (≥31 mm) versus small aortic neck diameters (≤28 and ≤31 mm).

METHODS

Prospectively collected data from 741 patients who underwent endovascular aortic aneurysm repair were analyzed. Some surgeons have reported the threshold for a large aortic neck for endovascular aortic aneurysm repair to be 28 mm, whereas for others it is 31 mm. Therefore, we classified aortic neck diameter into less than or equal to 28 versus greater than 28 mm; and less than or equal to 31 versus greater than 31 mm. Logistic regression and Kaplan-Meier analyses were used to compare outcomes.

RESULTS

There were 688 patients who had a defined aortic neck diameter: 592 with less than or equal to 28 mm, 96 with greater than 28 mm, 655 with less than or equal to 31 mm, and 33 with greater than 31 mm. The mean follow-up was 25.2 months for less than or equal to 31 mm versus 31.8 months for greater than 31 mm. Clinical characteristics were similar in all groups, except that there were more patients outside the instructions for use in the greater than 31 mm versus less than or equal to 31 mm group (94% vs 44%; P < .0001). There was a significant increase in early type I endoleak for patients with an aortic neck diameter of greater than 31 versus less than or equal to 31 mm (9 [27%] vs 74 [11%]; P = .01); late type I endoleaks (4 [14%] vs 18 [3%]; P = .01); sac expansion (5 [17%] vs 28 [5%]; P = .01); late intervention (5 [17%] vs 23 [4%]; P = .01); and death (9 [31%] vs 48 [8%]; P < .0001). There were no differences in outcomes between the patients with greater than 28 mm aortic neck diameters and the less than or equal to 28 mm diameters. Freedom from late type I endoleak at 1, 2, and 3 years were 96%, 88%, and 88% for patients with a neck diameter of greater than 31 mm versus 97%, 97%, and 97% for a diameter less than or equal to 31 mm (P = .19). The rate of freedom from sac expansion for patients with a diameter greater than 31 mm was 88%, 81%, and 81% at 1, 2, and 3 years versus 99%, 97%, and 92% for a diameter less than or equal to 31 mm (P = .02). Freedom from late intervention for 1, 2, and 3 years for patients with a diameter greater than 31 mm were 91%, 91%, and 91% versus 99%, 97%, and 96% for those with a diameter less than or equal to 31 mm. Survival rates at 1, 2, and 3 years for a diameter greater than 31 mm were 83%, 74%, and 68% versus 96%, 92%, and 90% for a diameter less than or equal to 31 mm (P < .001). Multivariate logistic regression analysis showed that patients with a diameter greater than 31 mm had an odds ratio of 6.1 (95% confidence interval [CI], 2.2-16.8) for mortality, 4.7 (95% CI, 1.4-15.5) for sac expansion, and 4.9 (95% CI, 1.4-17.4) for late type I endoleak.

CONCLUSIONS

Patients with large aortic neck diameters (>31 mm) had higher rates of early and late type I endoleak, sac expansion, late intervention, and mortality.

Validation of a New Methodology to Determine 3-Dimensional Endograft Apposition, Position, and Expansion in the Aortic Neck After Endovascular Aneurysm Repair

Purpose: To validate a novel methodology employing regular postoperative computed tomography angiography (CTA) scans to assess essential factors contributing to durable endovascular aneurysm repair (EVAR), including endograft deployment accuracy, neck adaptation to radial forces, and effective apposition of the fabric within the aortic neck. Methods: Semiautomatic calculation of the apposition surface between the endograft and the infrarenal aortic neck was validated in vitro by comparing the calculated surfaces over a cylindrical silicon model with known dimensions on CTA reconstructions with various slice thicknesses. Interobserver variabilities were assessed for calculating endograft position, apposition, and expansion in a retrospective series of 24 elective EVAR patients using the repeatability coefficient (RC) and the intraclass correlation coefficient (ICC). The variability of these calculations was compared with variability of neck length and diameter measurements on centerline reconstructions of the preoperative and first postoperative CTA scans. Results: In vitro validation showed accurate calculation of apposition, with deviation of 2.8% from the true surface for scans with 1-mm slice thickness. Excellent agreement was achieved for calculation of the endograft dimensions (ICC 0.909 to 0.996). Variability was low for calculation of endograft diameter (RC 2.3 mm), fabric distances (RC 5.2 to 5.7 mm), and shortest apposition length (RC 4.1 mm), which was the same as variability of regular neck diameter (RC 0.9 to 1.1 mm) and length (RC 4.0 to 8.0 mm) measurements. Conclusion: This retrospective validation study showed that apposition surfaces between an endograft and the infrarenal neck can be calculated accurately and with low variability. Determination of the (ap)position of the endograft in the aortic neck and detection of subtle changes during follow-up are crucial to determining eventual failure after EVAR.

Follow-up after endovascular aortic aneurysm repair can be stratified based on first postoperative imaging

Background

Lifelong postoperative surveillance is recommended following endovascular aneurysm repair (EVAR). Although the purpose is to prevent and/or identify complications early, it also results in increased cost and workload. This study was designed to examine whether it may be possible to identify patients at low risk of complications based on their first postoperative CT angiogram (CTA).

Methods

All patients undergoing EVAR in two Swedish centres between 2001 and 2012 were identified retrospectively and categorized based on the first postoperative CTA as at low risk (proximal and distal sealing zone at least 10 mm and no endoleak) or high risk (sealing zone less than 10 mm and/or presence of any endoleak) of complications.

Results

Some 326 patients (273 men) with a CTA performed less than 1 year after EVAR were included (low risk 212, 65·0 per cent; high risk 114, 35·0 per cent). There was no difference between the groups in terms of sex, age, co-morbidities, abdominal aortic aneurysm (AAA) diameter, preoperative AAA neck anatomy, stent-graft type or duration of follow-up (mean(s.d.) 4·8(3·2) years). Five-year freedom from AAA-related adverse events was 97·1 and 47·7 per cent in the low- and high-risk groups respectively (P &lt; 0·001). The corresponding freedom from AAA-related reintervention was 96·2 and 54·1 per cent (P &lt; 0·001). The method had a sensitivity of 88·3 per cent, specificity of 77·0 per cent and negative predictive value of 96·6 per cent to detect AAA-related adverse events. The number of surveillance imaging per AAA-related adverse event was 168 versus 11 for the low-risk versus high-risk group.

Conclusion

Two-thirds of patients undergoing EVAR have an adequate seal and no endoleak on the first postoperative CTA, and a very low risk of AAA-related events up to 5 years. Less vigilant follow-up after EVAR may be considered for these patients.

In Vitro Quantification of Gutter Formation and Chimney Graft Compression in Chimney EVAR Stent-Graft Configurations Using Electrocardiography-Gated Computed Tomography

Purpose: To assess the dynamic behavior of chimney grafts during the cardiac cycle. Methods: Three chimney endovascular aneurysm repair (EVAR) stent-graft configurations (Endurant and Advanta V12, Endurant and Viabahn, and Endurant and BeGraft) were placed in silicone aneurysm models and subjected to physiologic flow. Electrocardiography (ECG)-gated contrast-enhanced computed tomography was used to visualize geometric changes during the cardiac cycle. Endograft and chimney graft surface, gutter volume, chimney graft angulation over the center lumen line, and the D-ratio (the ratio between the lengths of the major and minor axes) were independently assessed by 2 observers at 10 time points in the cardiac cycle. Results: Both gutter volumes and chimney graft geometry changed significantly during the cardiac cycle in all 3 configurations (p<0.001). Gutters and endoleaks were observed in all configurations. The largest gutter volume (232.8 mm3) and change in volume (20.7 mm3) between systole and diastole were observed in the Endurant-Advanta configuration. These values were 2.7- and 3.0-fold higher, respectively, compared to the Endurant-Viabahn configuration and 1.7- and 1.6-fold higher as observed in the Endurant-BeGraft configuration. The Endurant-Viabahn configuration had the highest D-ratio (right, 1.26–1.35; left, 1.33–1.48), while the Endurant-BeGraft configuration had the lowest (right, 1.11–1.17; left, 1.08–1.15). Assessment of the interobserver variability showed a high correlation (intraclass correlation >0.935) between measurements. Conclusion: Gutter volumes and stent compression are dynamic phenomena that reshape during the cardiac cycle. Compelling differences were observed during the cardiac cycle in all configurations, with the self-expanding (Endurant–Viabahn) chimney EVAR configurations having smaller gutters and less variation in gutter volume during the cardiac cycle yet more stent compression without affecting the chimney graft surface.

A Semiautomated Method for Measuring the 3-Dimensional Fabric to Renal Artery Distances to Determine Endograft Position After Endovascular Aneurysm Repair

Purpose: To report a methodology for 3-dimensional (3D) assessment of the stent-graft deployment accuracy after endovascular aneurysm repair (EVAR). Methods: A methodology was developed and validated to calculate the 3D distances between the endograft fabric and the renal arteries over the curve of the aorta. The shortest distance between one of the renal arteries and the fabric (SFD) and the distance from the contralateral renal artery to the fabric (CFD) were determined on the first postoperative computed tomography (CT) scan of 81 elective EVAR patients. The SFDs were subdivided into a target position (0–3 mm distal to the renal artery), high position (partially covering the renal artery), and low position (>3 mm distal to the renal artery). Data are reported as the median (interquartile range, IQR). Results: Intra- and interobserver agreements for automatic and manual calculation of the SFD and CFD were excellent (ICC >0.892, p<0.001). The median SFD was 1.4 mm (IQR −0.9, 3.0) and the median CFD was 8.0 mm (IQR 3.9, 14.2). The target position was achieved in 44%, high position in 30%, and low position in 26% of the patients. The median slope of the endograft toward the higher renal artery was 2.5° (IQR −5.5°, 13.9°). Conclusion: The novel methodology using 3D CT reconstructions enables accurate evaluation of endograft position and slope within the proximal aortic neck. In this series, only 44% of endografts were placed within the target position with regard to the lowermost renal artery.

Cinical outcomes of Endurant II stent-graft for infrarenal aortic aneurysm repair: comparison of on-label versus off-label use

PURPOSE

We aimed to compare the outcomes of the Endurant II (Medtronic) stent-graft used under instructions for use versus off-label in high-risk patients considered unfit for conventional surgery.

METHODS

Data from patients treated with the Endurant II stent-graft between December 2012 and March 2015 were retrospectively analyzed. Sixty-four patients were included. Patients were assigned to group A if treated under instructions for use (n=34, 53%) and to group B if treated off-label (n=30, 47%). Outcome measures included perioperative mortality and morbidity, survival, freedom from reintervention, endoleak incidence, in-hospital length of stay, and mean stent-graft component used. Mean follow-up was 22.61±12 months (median, 21.06 months; range, 0-43 months).

RESULTS

One perioperative mortality (1.6%) and one perioperative complication (1.6%) occurred in group B. At two months follow-up, one iliac limb occlusion (1.6%) occurred in group A. No type I/III endoleaks were recorded. A type II endoleak was identified in three cases (4.7%). Overall survival at three years was 89% (97% for group A, 82% for group B; P = 0.428). Reintervention-free survival at three years was 97% for both groups (P = 0.991). A longer in-hospital stay was observed in group B (P = 0.012).

CONCLUSION

The Endurant II (Medtronic) new generation device was safe in off-label setting at mid-term follow-up. The off-label use of the Endurant II (Medtronic) is justified in patients considered unfit for conventional surgery. Larger studies are required in this subgroup of patients.

Proximal Aortic Neck Progression: Before and After Abdominal Aortic Aneurysm Treatment

Several risk factors including short or highly angulated proximal aortic neck have been associated with long-term outcomes after endovascular or open abdominal aortic aneurysm (AAA) repair. However, research data have emerged recently concerning the behavior of proximal aortic neck, and several authors have tried to evaluate this behavior after endovascular or open repair. Additionally, computed tomography angiography (CTA) remains the golden standard for detecting and observing the morphology of an AAA, both before and after treatment. Moreover, the question of whether the proximal neck’s progression independently affects postoperative morbidity and reintervention risks still remains. Therefore, this focused review aims to present all relevant data on the behavior of an AAAs neck, based on CTA imaging before and after repair, in order to produce useful conclusions for future clinical practice.

Adjusted Hospital Outcomes of Abdominal Aortic Aneurysm Surgery Reported in the Dutch Surgical Aneurysm Audit

OBJECTIVE/BACKGROUND

The Dutch Surgical Aneurysm Audit (DSAA) is mandatory for all patients with primary abdominal aortic aneurysms (AAAs) in the Netherlands. The aims are to present the observed outcomes of AAA surgery against the predicted outcomes by means of V-POSSUM (Vascular-Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity). Adjusted mortality was calculated by the original and re-estimated V(physiology)-POSSUM for hospital comparisons.

METHODS

All patients operated on from January 2013 to December 2014 were included for analysis. Calibration and discrimination of V-POSSUM and V(p)-POSSUM was analysed. Mortality was benchmarked by means of the original V(p)-POSSUM formula and risk-adjusted by the re-estimated V(p)-POSSUM on the DSAA.

RESULTS

In total, 5898 patients were included for analysis: 4579 with elective AAA (EAAA) and 1319 with acute abdominal aortic aneurysm (AAAA), acute symptomatic (SAAA; n = 371) or ruptured (RAAA; n = 948). The percentage of endovascular aneurysm repair (EVAR) varied between hospitals but showed no relation to hospital volume (EAAA: p = .12; AAAA: p = .07). EAAA, SAAA, and RAAA mortality was, respectively, 1.9%, 7.5%, and 28.7%. Elective mortality was 0.9% after EVAR and 5.0% after open surgical repair versus 15.6% and 27.4%, respectively, after AAAA. V-POSSUM overestimated mortality in most EAAA risk groups (p < .01). The discriminative ability of V-POSSUM in EAAA was moderate (C-statistic: .719) and poor for V(p)-POSSUM (C-statistic: .665). V-POSSUM in AAAA repair overestimated in high risk groups, and underestimated in low risk groups (p < .01). The discriminative ability in AAAA of V-POSSUM was moderate (.713) and of V(p)-POSSUM poor (.688). Risk adjustment by the re-estimated V(p)-POSSUM did not have any effect on hospital variation in EAAA but did in AAAA.

CONCLUSION

Mortality in the DSAA was in line with the literature but is not discriminative for hospital comparisons in EAAA. Adjusting for V(p)-POSSUM, revealed no association between hospital volume and treatment or outcome. Risk adjustment for case mix by V(p)-POSSUM in patients with AAAA has been shown to be important.