Mid-term results of "off-label" use of the Endurant stentgraft in patients with infrarenal abdominal aortic aneurysms

OBJECTIVES

EVAR is the preferred treatment modality for patients with an infrarenal abdominal aortic aneurysm with suitable anatomy. Each manufacturer of aortic stentgrafts has specific anatomic requirements. In some patients, it is not possible to adhere to the instructions for use, but alternative treatment is also not possible. In these patients, EVAR can be performed outside instructions for use.

METHODS

In this study, all consecutive patients in whom an Endurant II or IIS stentgraft was used between 1 January and 31 December were reviewed. We compared the two patient groups in whom this stentgrafts was used outside and inside instructions for use. Patients with planned adjuvant therapy, for example, chimney procedure or iliac side branches, were excluded.

RESULTS

In 74 of 178 (41.6%) patients, the instructions for use were not adhered. The main reason was pathology of the aortic neck. There were more patients with type IA endoleak, this difference was borderline significant (p = .06). There were more patients with limb occlusion in the early postoperative period, but at the end of the follow-up period, the incidence was comparable. Aneurysm-related mortality and all-cause mortality were comparable in both groups.

CONCLUSION

In this study, real-life experience with the Endurant II and IIS stentgraft is described. Non-adherence with instructions for use was associated with a higher risk of endoleak type IA (p = .06). In the early postoperative period, there were more patients with limb occlusion; this finding was not observed anymore at the end of the follow-up period.

Comparison of Three Workstations For Abdominal Aortic Aneurysm Sizing: Impact in Decision Making and Graft Selection

PURPOSE

The aim of this study was to assess the agreement of multiplanar reconstruction (MPR) and semiautomated central lumen line (CLL) analysis of abdominal aortic aneurysms (AAA), with 3 different software workstations (WS1, WS2, WS3) and 2 experienced practitioners as well as to analyze its eventual impact in graft selection.

MATERIALS AND METHODS

Twenty computed tomography (CT) angiography data sets were randomly chosen from a series of 100 consecutive studies. Measurements were performed twice by each reader, in random order, and included 8 parameters (5 diameters and 3 lengths). Each observer performed a complete set of 60 studies. Intra-observer and interobserver variability for every WS was assessed. Measurements were evaluated using Bland-Altman analysis, correlation coefficients (r), and concordance correlation coefficients (CCC [95% confidence interval (CI)]).

RESULTS

A high overall agreement between repeated measurements for both observers was obtained (r=0.989; CCC=0.988 [0.982-0.992] and r=0.998; CCC=0.996 [0.994-0.997], for observers 1 and 2, respectively). However, reproducibility for individual parameters was excellent for observer 2 and only moderate for observer 1. A high overall agreement was obtained for interobserver concordance (r=0.987; CCC=0.986 [0.982-0.989]). When analyzing for individual parameters, greatest interobserver differences were found at CLL measurement of the diameter of aortic neck (WS2) and bifurcation (WS1 and WS2) as well as iliac diameter in all 3 WS for both CLL and MPR. Similar differences were observed in paired comparison between WS when involving these parameters. Careful inspection of Bland-Altman charts revealed some cases of disagreement between WS and observers that would affect decision making on graft selection, changing the neck diameter to a different size, in 2 cases when measuring with WS1, and iliac diameter in 4 cases (2 of them with WS1 and 2 with WS2). Greatest discordance was observed regarding ipsilateral iliac length affecting 7 measurements that would lead to change the length of the selected limb graft (2 with WS1, 3 with WS2, and 2 with WS3).

CONCLUSIONS

Although a high agreement between different observers using different WS for AAA measurements is to be expected, small differences may lead to the selection of a different graft size. The use of a single software by experienced users, and double check by a different one, may be advisable.

CLINICAL IMPACT

Influence of inter and intraobserver variability in CT measurements during planning of endovascular aneurysm repair (EVAR) has been extensively reviewed. However, its impact in graft selection (final choose of diameter and lengths) has been scarcely analyzed. The results of this study suggest that, although a high agreement between different observers using different workstations for AAA measurements is to be expected, small differences may lead to the selection of a different graft size. The use of a single software by experienced users, and double check by a different one, may be advisable.

Pancreaticoduodenal Artery Aneurysm Rupture Presenting as Duodenal Obstruction Successfully Treated with Early Transcatheter Arterial Embolization: A Case Report of Suspected Segmental Arterial Mediolysis

Visceral aneurysms are a rare but important form of abdominal vascular disease. Rupture of the aneurysms leads to serious symptoms, such as acute abdomen or abdominal bleeding. However, duodenal obstruction due to arterial rupture of an aneurysm is very rare. We herein report a 50-year-old woman with suspected segmental arterial mediolysis (SAM) who was first diagnosed with acute abdomen and duodenal obstruction. Rupture of a pancreaticoduodenal artery aneurysm was confirmed, and she was treated with transcatheter arterial embolization. In cases of acute abdomen, SAM is a rare but important possibility to consider as a differential diagnosis.

Evidence Accumulates: Patients with Ascending Aneurysms Are Strongly Protected from Atherosclerotic Disease

Ascending thoracic aortic aneurysms may be fatal upon rupture or dissection and remain a leading cause of death in the developed world. Understanding the pathophysiology of the development of ascending thoracic aortic aneurysms may help reduce the morbidity and mortality of this disease. In this review, we will discuss our current understanding of the protective relationship between ascending thoracic aortic aneurysms and the development of atherosclerosis, including decreased carotid intima-media thickness, low-density lipoprotein levels, coronary and aortic calcification, and incidence of myocardial infarction. We also propose several possible mechanisms driving this relationship, including matrix metalloproteinase proteins and transforming growth factor-β.

Pulsatile Changes of the Aortic Diameter May Be Irrelevant Regarding Endograft Sizing in Patients With Aortic Disease

PURPOSE

Endovascular aortic repair has become the preferred elective treatment of infrarenal aortic aneurysms. Aortic pulsatility may pose problems regarding endograft sizing. The aims of this study are to determine the aortic pulsatility in patients with aortic disease and to evaluate the effect of pulsatility on the growth of aneurysms.

MATERIALS AND METHODS

In this retrospective study, analyses of computed tomography angiography (CTA) images of 31 patients under conservative treatment for small abdominal aortic aneurysms were performed. Reconstructions of the raw electrocardiography (ECG) gated dataset at 30% and 90% of the R-R cycle were used. After lumen segmentation, total aortic cross-sectional area was measured in diastole and systole in the following zones: Z0, Z3, Z5, Z6, Z8, and Z9. Effective diameters (EDs) were calculated from the systolic (ED_sys) and diastolic (ED_dia) cross-sectional areas to determine absolute (ED_sys - ED_dia, mm) and relative pulsatility [(ED_sys - ED_dia) / ED_dia, %]. Diameter of the aneurysms was measured on baseline images and the last preoperative follow-up study of each patient.

RESULTS

A total of 806 measurements were completed, 24 pulsatility and 2 growth measurements per patient. The mean pulsatility values at each point were as follows: Z0: 0.7±0.8 mm, Z3: 1.0±0.6 mm, Z5: 1.0±0.6 mm, Z6: 0.8±0.7 mm, Z8: 0.7±1.0 mm, Z9: 0.9±0.9 mm. Follow-up time was 5.5±2.2 years during which a growth of 13.42±9.09 mm (2.54±1.55 mm yearly) was observed. No correlation was found between pulsatility values and growth rate of the aneurysms.

CONCLUSION

The pulsatility of the aorta is in a submillimetric range for the vast majority of patients with aortic disease, thus probably not relevant regarding endograft sizing. Pulsatility of the ascending aorta is smaller than that of the descending segment, making an additional oversize of a Z0 implantation questionable.

CLINICAL IMPACT

Endovascular aortic repair reqiures precise preoperative planning. Pulsatile changes of the aortic diameter may pose issues regarding endograft sizing. In our retrospective single-centre study, aortic pulsatility of patients with AAA was measured on ECG gated CTA images. Pulsatility values reached a maximum at the descending aorta, however absolute pulsatility values did not exceed 1 mm at any point along the aorta. Therefore, significance of aortic pulsatility regarding the sizing of EVAR prostheses is questionable. Correlation between pulsatility and AAA growth was not found.

Predictors of Abdominal Aortic Aneurysm Risks

Computational biomechanics via finite element analysis (FEA) has long promised a means of assessing patient-specific abdominal aortic aneurysm (AAA) rupture risk with greater efficacy than current clinically used size-based criteria. The pursuit stems from the notion that AAA rupture occurs when wall stress exceeds wall strength. Quantification of peak (maximum) wall stress (PWS) has been at the cornerstone of this research, with numerous studies having demonstrated that PWS better differentiates ruptured AAAs from non-ruptured AAAs. In contrast to wall stress models, which have become progressively more sophisticated, there has been relatively little progress in estimating patient-specific wall strength. This is because wall strength cannot be inferred non-invasively, and measurements from excised patient tissues show a large spectrum of wall strength values. In this review, we highlight studies that investigated the relationship between biomechanics and AAA rupture risk. We conclude that combining wall stress and wall strength approximations should provide better estimations of AAA rupture risk. However, before personalized biomechanical AAA risk assessment can become a reality, better methods for estimating patient-specific wall properties or surrogate markers of aortic wall degradation are needed. Artificial intelligence methods can be key in stratifying patients, leading to personalized AAA risk assessment.

Optimization of porous stents for endovascular repair of abdominal aortic aneurysms

This study presents a simulation-based methodology to design porous stents to induce suitable hemodynamic environments inside abdominal aortic aneurysm (AAA) sacs. In the proposed methodology, an optimization algorithm iteratively modifies the porosity distribution of the stent and executes a computational fluid dynamics (CFD) simulation to determine the effect of these changes on the hemodynamic conditions inside the aneurysm sac. The optimization iterations proceed until relevant hemodynamic parameters are within ranges prescribed a priori by the user as desirable to control the progression of the AAA. The resulting porosity distribution uniquely describes the porous stent design that can control the hemodynamic environment (eg, shear stress at the aneurysm wall, pressure distribution, residence time), reducing AAA rupture risks and improving treatment efficacy. To demonstrate its potential, the proposed methodology is applied to idealized AAA geometry under steady-state flow conditions, though it may be easily applied to more complex AAA geometries under transient, pulsatile flow conditions. The proposed methodology has the potential to enable the design of a new generation of porous stents tailored to patient-specific geometries and flow conditions, to improve patient outcomes.

Harmonic Focus Versus Conventional Electrocautery for Femoral Artery Exposure: a "Direct" Comparison on the Same Patients

Surgical access complications during endovascular aneurysm repair (EVAR) are reported relatively frequent. HARMONIC FOCUS^® (HF; Ethicon Endo-Surgery Inc., Cincinnati, Ohio, USA) is a device developed to improve bleeding control and reduce heat-related damage stemming from surgical preparation. The aim of this study was to evaluate outcomes and safety of HF versus conventional haemostasis with electrocautery, both techniques used in the same patient. Five patients developed bilateral wound's thickening (13.9%) demonstrated at the CT scan, two of whom had no clinical manifestation while in three cases the thickening was associated with lymphocele (4.54%), 2 of which were in the side where the EC was used (5.5%), and 1 case (2.7%), in the HF applied side. One isolated lymphocele occurred at the left groin (2.7%) (tables n.2-3). A Fisher's exact test was conducted between EC and HF on the occurrence of wound healing complications (3/36 for EC and 1/36 for HF) that resulted statistically significant at p<0.05. Focus Harmonic Scalpel has certain advantages than conventional haemostasis in avoiding surgical access complications.

Inflammation and TGF-β Signaling Differ between Abdominal Aneurysms and Occlusive Disease

Abdominal aortic aneurysms (AAA), are usually asymptomatic until rupture causes fatal bleeding, posing a major vascular health problem. AAAs are associated with advanced age, male gender, and cardiovascular risk factors (e.g. hypertension and smoking). Strikingly, AAA and AOD (arterial occlusive disease) patients have a similar atherosclerotic burden, yet develop either arterial dilatation or occlusion, respectively. The molecular mechanisms underlying this diversion are yet unknown. As this knowledge could improve AAA treatment strategies, we aimed to identify genes and signaling pathways involved. We compared RNA expression profiles of abdominal aortic AAA and AOD patient samples. Based on differential gene expression profiles, we selected a gene set that could serve as blood biomarker or as pharmacological intervention target for AAA. In this AAA gene list we identified previously AAA-associated genes COL11A1, ADIPOQ, and LPL, thus validating our approach as well as novel genes; CXCL13, SLC7A5, FDC-SP not previously linked to aneurysmal disease. Pathway analysis revealed overrepresentation of significantly altered immune-related pathways between AAA and AOD. Additionally, we found bone morphogenetic protein (BMP) signaling inhibition simultaneous with activation of transforming growth factor β (TGF-β) signaling associated with AAA. Concluding our gene expression profiling approach identifies novel genes and an interplay between BMP and TGF-β signaling regulation specifically for AAA.

No Difference in Neck Enlargement for Patients Treated With Double Proximal Self-Expandable Suprarenal Fixation Endografting

INTRODUCTION

Neck enlargement is well described in patients treated with self-expandable endografts for abdominal aortic aneurysms. Double endografting (ie, overlapping of stent grafts) occurs in patients with proximal cuffs or bifurcated to monoiliacal configuration conversions. When the aortic neck of patients receives 2 suprarenal fixation endografts, it may behave differently in terms of radial force and interaction of additional suprarenal stents extending to the visceral aorta.

METHODS

We performed a retrospective study comparing 2 groups. Group 1 included 18 patients treated with 2 proximal self-expandable endografts. Group 2 included 17 patients treated with 1 self-expandable endograft who were consecutively treated during the period of treatment in group 1. Neck measurements were analyzed in both groups preoperatively and in the last computed tomography scan during follow-up. Suprarenal, interrenal, juxtarenal, and infrarenal (at 5 and 10 mm) diameters, as well as interrenal and infrarenal (5 mm) areas, were measured.

RESULTS

There was no significant difference in baseline characteristics, initial neck measurements, and aneurysmal sac evolution including endoleaks between the groups. Both groups showed neck enlargement. Group comparisons of all parameters in posttreatment neck measurements showed no statistical change. Univariate analysis showed oversizing to be significant in interrenal diameter and area and infrarenal at 10 mm diameter; however, 2-way analysis of variance analysis showed that the interaction between oversizing and the number of stent grafts was not significant.

CONCLUSION

Neck enlargement occurs in patients with self-expandable endografts with a tendency to reach the size of the endograft in the long term. Double endografting seems to interact in the same way as simple endografting in the aortic neck. Although the main limitation of our study lies in the small sample size, the presence of an additional "double" stent graft does not appear to result in any differences in aortic neck dilatation when compared to a single stent graft.

The pathophysiologic basis of abdominal aortic aneurysm progression: a critical appraisal

An aneurysm of the abdominal aorta is a common pathology and a major cause of sudden death in the elderly. Currently, abdominal aortic aneurysms (AAAs) can only be treated by surgery and an effective medical therapy is urgently missing. The pathophysiology of AAAs is complex and is believed to be best described as a comprehensive inflammatory response with an accompanying proteolytic imbalance; the latter being held responsible for the progressive weakening of the aortic wall. Remarkably, while interference in inflammatory and/or proteolytic cascades proves highly effective in preclinical studies, emerging clinical studies consistently fail to show a benefit. In fact, some anti-inflammatory interventions appear to adversely influence the disease process. Altogether, recent clinical observations not only challenge the prevailing concepts of AAA progression, but also raise doubt on the translatability of findings from rodent models for growing AAA.

Aorto-left renal vein fistula caused by a ruptured abdominal aortic aneurysm

Retroaortic left renal vein is a malformation in which the left renal vein courses dorsal to the abdominal aorta. In patients with abdominal aortic aneurysm, an aorto-left renal vein fistula can form if the left renal vein is sandwiched between the aneurysm wall and lumbar vertebrae. The patient was an 84-year-old man with lower back pain. We performed a contrast-enhanced computed tomography (CT), although renal dysfunction was noted. The CT showed a ruptured juxta-renal abdominal aortic with aorto-left renal vein fistula. This clinical condition can cause severe renal dysfunction, in spite of which an enhanced contrasted CT scan would be extremely informative preoperatively.