Assessing trans-endothelial transport of nanoparticles for delivery to abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are localized, rupture-prone expansions of the abdominal aorta wall. In this condition, structural extracellular matrix (ECM) proteins of the aorta wall, elastic fibers and collagen fibers, that impart elasticity and stiffness respectively, are slowly degraded by overexpressed matrix metalloproteinases (MMPs) following an injury stimulus. We are seeking to deliver therapeutics to the AAA wall using polymer nanoparticles (NPs) that are capable of stimulating on-site matrix regeneration and repair. This study aimed to determine how NP shape and size impacts endocytosis and transmigration past the endothelial cell (EC) layer from circulation into the medial layer of the AAA wall. First, rod-shaped NPs were shown to be created based mechanical stretching of PLGA NPs while embedded in a PVA film with longer rod-shaped NPs created based of the degree in which the PVA films are stretched. Live/dead assay reveals that our PLGA NPs are safe and do not cause cell death. Immunofluorescence staining reveal cytokine activation causes endothelial dysfunction in ECs by increasing expression of inflammatory marker Integrin αVβ3 and decreasing expression of adhesion protein vascular endothelial (VE)-cadherin. We showed this disruption enable greater EC uptake and translocation of NPs. Fluorescence studies demonstrate high endothelial transmigration and endocytosis with rod-shaped NPs in cytokine activated ECs compared to healthy control cells, arguing for the benefits of using higher aspect ratio (AR) NPs for accumulation at the aneurysm site. We also demonstrated that the mechanisms of NP transmigration across an activated EC layer depend on NP AR. These results show the potential of using shape as a modality for enhancing permeation of NPs into the aneurysm wall. These studies are also significance to understanding the mechanisms that are likely engaged by NPs for penetrating the endothelial lining of aneurysmal wall segments.

Machine learning-based prediction of abdominal aortic aneurysms for individualized patient care

OBJECTIVE

The United States Preventative Services Task Force guidelines for screening for abdominal aortic aneurysms (AAA) are broad and exclude many at risk groups. We analyzed a large AAA screening database to examine the utility of a novel machine learning (ML) model for predicting individual risk of AAA.

METHODS

We created a ML model to predict the presence of AAAs (>3 cm) from the database of a national nonprofit screening organization (AAAneurysm Outreach). Participants self-reported demographics and comorbidities. The model is a two-layered feed-forward shallow network. The ML model then generated AAA probability based on patient characteristics. We evaluated graphs to determine significant factors, and then compared those graphs with a traditional logistic regression model.

RESULTS

We analyzed a cohort of 10,033 patients with an AAA prevalence of 2.74%. Consistent with logistic regression analysis, the ML model identified the following predictors of AAA: Caucasian race, male gender, advancing age, and recent or past smoker with recent smoker having a more profound affect (P < .05). Interestingly, the ML model showed body mass index (BMI) was associated with likelihood of AAAs, especially for younger females. The ML model also identified a higher than predicted risk of AAA in several groups, including female nonsmokers with cardiac disease, female diabetics, those with a family history of AAA, and those with hypertension or hyperlipidemia at older ages. An elevated BMI conveyed a higher than expected risk in male smokers and all females. The ML model also identified a complex relationship of both diabetes mellitus and hyperlipidemia with gender. Family history of AAA was a more important risk factor in the ML model for both men and women too.

CONCLUSIONS

We successfully developed an ML model based on an AAA screening database that unveils a complex relationship between AAA prevalence and many risk factors, including BMI. The model also highlights the need to expand AAA screening efforts in women. Using ML models in the clinical setting has the potential to deliver precise, individualized screening recommendations.

Locoregional Anesthesia Has Lower Risks of Cardiac Complications Than General Anesthesia After Prolonged Endovascular Repair of Abdominal Aortic Aneurysms

OBJECTIVES

Although general anesthesia is the primary anesthesia in endovascular aneurysm repair (EVAR), some studies suggest locoregional anesthesia could be a feasible alternative for eligible patients. However, most evidence was from retrospective studies and was subjected to an inherent selection bias that general anesthesia is often chosen for more complex and prolonged cases. To mitigate this selection bias, this study aimed to compare 30-day outcomes of prolonged, nonemergent, intact, infrarenal EVAR in patients undergoing locoregional or general anesthesia. In addition, risk factors associated with prolonged operative time in EVAR were identified.

DESIGN

Retrospective large-scale national registry study.

SETTING

American College of Surgeons National Surgical Quality Improvement Program targeted database from 2012 to 2022.

PARTICIPANTS

A total of 4,075 out of 16,438 patients (24.79%) had prolonged EVAR. Among patients with prolonged EVAR, 324 patients (7.95%) were under locoregional anesthesia. There were 3,751 patients (92.05%) under general anesthesia, and 955 of them were matched to the locoregional anesthesia cohort.

INTERVENTIONS

Patients undergoing infrarenal EVAR were included. Exclusion criteria included age <18 years, emergency cases, ruptured abdominal aortic aneurysm, and acute intraoperative conversion to open. Only cases with prolonged operative times (>157 minutes) were selected. A 1:3 propensity-score matching was used to address demographics, baseline characteristics, aneurysm diameter, distant aneurysm extent, and concomitant procedures between patients under locoregional and general anesthesia. Thirty-day postoperative outcomes were assessed. Moreover, factors associated with prolonged EVAR were identified by multivariate logistic regression.

MEASUREMENTS AND MAIN RESULTS

Except for general anesthesia contraindications, patients undergoing locoregional or general anesthesia exhibited largely similar preoperative characteristics. After propensity-score matching, patients under locoregional and general anesthesia had a lower risk of myocardial infarction (0.93% v 2.83%, p = 0.04), but comparable 30-day mortality (3.72% v 2.72%, p = 0.35) and other complications. Specific concomitant procedures, aneurysm anatomy, and comorbidities associated with prolonged EVAR were identified.

CONCLUSIONS

Locoregional anesthesia can be a safe and effective alternative to general anesthesia, particularly in EVAR cases with anticipated complexity and prolonged operative times, as it offers the potential benefit of reduced cardiac complications. Risk factors associated with prolonged EVAR can aid in preoperative risk stratification and inform the decision-making process regarding anesthesia choice.

Clinical Performance of the Low Profile Zenith Alpha Abdominal Endovascular Graft: 2 Year Results from the ZEPHYR Registry

OBJECTIVE

The midterm outcomes of the low profile Zenith Alpha Abdominal Endovascular Graft from the ZEnith alPHa for aneurYsm Repair (ZEPHYR) registry are reported.

METHODS

The ZEPHYR registry is a physician initiated, multicentre, non-randomised, core laboratory controlled, prospective registry. Inclusion criteria were patients with a non-ruptured abdominal aortic aneurysm with a maximum diameter ≥ 50 mm or enlargement > 5 mm within 6 months, with a site reported infrarenal neck length of ≥ 10 mm and with the intention to electively implant the Zenith Alpha abdominal endograft. Patients from 14 sites across Germany, Belgium, and the Netherlands were included. The primary endpoint was treatment success, defined as technical success and clinical success. Technical success was defined as successful delivery and deployment of the endograft in the planned position without unintentional coverage of internal iliac or renal arteries, with successful removal of the delivery system. Clinical success was defined as freedom from aneurysm sac expansion > 5 mm, type I or type III endoleaks, aneurysm rupture, stent graft migration > 10 mm, open conversion, and stent graft occlusion.

RESULTS

Three hundred and forty-seven patients were included in the ZEPHYR registry. The median clinical follow up was 743 days (interquartile range [IQR] 657, 806) with a median imaging follow up of 725 days (IQR 408, 788). Treatment success at 6 months, 1, and 2 years was 92.5%, 90.4%, and 85.3%, respectively. Freedom from secondary intervention was 94.3%, 93.4%, and 86.9%, respectively. The predominant reason for secondary intervention was limb complications. Freedom from limb occlusion (per patient) at 6 months, 1, and 2 years was 97.2%, 95.8%, and 92.5%, respectively. Univariable and multivariable Cox regression analyses could not identify any independent predictor for limb complications.

CONCLUSION

While treatment success is comparable with other commercially available grafts, the rate of limb complications at 2 years is of concern. The manufacturer's instructions for use should be followed closely. Further studies are necessary to investigate the root cause of the increased rate of limb complications with the Zenith Alpha Abdominal Endovascular Graft.

Correlation of four-dimensional ultrasound strain analysis with computed tomography angiography wall stress simulations in abdominal aortic aneurysms

Objective

Biomechanical modeling of infrarenal aortic aneurysms seeks to predict ruptures in advance, thereby reducing aneurysm-related deaths. As individual methods focusing on strain and stress analysis lack adequate discretization power, this study aims to explore multifactorial characterization for progressive aneurysmal degeneration. The study's objective is to compare stress- and strain-related parameters in infrarenal aortic aneurysms.

Methods

Twenty-two patients with abdominal aortic aneurysms (AAAs) (mean maximum diameter, 53.2 ± 7.2 mm) were included in the exploratory study, examined by computed tomography angiography (CTA) and three-dimensional real-time speckle tracking ultrasound (4D-US). The conformity of aneurysm anatomy in 4D-US and CTA was determined with the mean point-to-point distance (MPPD). CTA was employed for each AAA to characterize stress-related indices using the semi-automated A4-clinics RE software. Five segmentations from one 4D-US examination were fused into one averaged model for strain analysis using MATLAB and the Abaqus solver.

Results

The mean MPPD between the adjacent points of the 4D-US and CTA-derived geometry was 1.8 ± 0.4 mm. The interclass correlation coefficients for all raters and all measurements for the maximum AAA diameter in 2D, 4D ultrasound, and CTA indicate moderate to good reliability (interclass correlation coefficient1 0.69 with 95% confidence interval [CI], 0.49-0.84; P < .001). The peak wall stress (PWS) correlates fairly with the maximum AAA diameter in 2D-US (r = 0.54; P < .01) and 4D-US (r = 0.53; P < .05) and moderately strongly with the maximum exterior AAA diameter (r = 0.63; P < .01). The peak wall rupture risk index shows a strong correlation with the PWS (ρ > 0.9; P < .001) and is influenced by anatomical parameters with equal strength. Isolated observation of the intraluminal thrombus does not provide significant information in the determination of PWS. The maximum AAA diameter in 2D-US shows a fair negative correlation with the mean circumferential, longitudinal and in-plane shear strain (ρ = -0.46; r = -0.45; ρ = -0.47; P < .05 for all). The circumferential strain ratio as an indicator of wall motion heterogeneity increases with the aneurysm diameter (r = 0.47; P < .05). The direct comparison of wall strain and wall stress indices shows no quantitative correlation.

Conclusions

The strain and stress analyses provide independent biomechanical information of AAAs. At the current stage of development, the two methods are considered complementary and may optimize a more patient-specific rupture risk prediction in the future.

Screening Men and Women above the Age of 50 Years for Abdominal Aortic Aneurysm: A Pilot Study in an Upper Middle Income Country

OBJECTIVE

Screening for abdominal aortic aneurysm (AAA) is recommended in high risk populations based on local conditions. Differences in lifestyle and risk factors between countries with different income status make risk stratification based on geographic location necessary. The majority of epidemiological studies on AAA have reported data from high income countries. The aim of this study was to explore the prevalence and risk factors for AAA in an upper middle income country in Eastern Europe.

METHODS

A pilot screening project for AAA, supported by a mass media campaign, was conducted in 2023 in seven cities in Serbia. Ultrasound evaluation of the abdominal aorta was performed by a registered vascular surgeon on individuals who agreed to participate. Participants who attended screening completed a questionnaire on demographic and clinical information. To assess risk factors for AAA, univariable logistic regression analysis was performed to compute the odds ratio (OR) with 95% confidence interval (CI). Multivariable logistic regression was subsequently performed with adjustments for sex, age, family history of AAA, and other relevant factors.

RESULTS

A total of 4 046 participants (51.2% male and 48.8% female; mean age 68.8 ± 7.6 years) responded to the campaign. An aneurysm was found in 195 (4.8%) screened individuals (8.2% of men and 1.3% of women). In males aged 50 - 64 years, the prevalence of AAA was 5.4%. Male sex, older age, family history of AAA, being a smoker or ex-smoker, being overweight, and alcohol consumption were predictors of AAA in the univariable analysis. After adjustments in the multivariable analysis, male sex (OR 8.04, 95% CI 4.87 - 13.28), older age (OR 1.04, 95% CI 1.02 - 1.07), positive family history (OR 2.47, 95% CI 1.61 - 3.78), smoker status (OR 3.10, 95% CI 2.10 - 4.59), ex-smoker status (OR 2.13, 95% CI 1.39 - 3.27), and being overweight (OR 1.85, 95% CI 1.25 - 2.74) were independent risk factors for AAA.

CONCLUSION

The prevalence of AAA has not been reduced in all countries, and screening strategies might be changed based on local epidemiological data. The results of this pilot study underline the importance of exploring the prevalence of AAA in populations with a high prevalence of smoking.

Revealing PPP1R12B and COL1A1 as piRNA pathway genes contributing to abdominal aortic aneurysm through integrated analysis and experimental validation

BACKGROUND

Abdominal aortic aneurysm (AAA) is a permanent dilation of the abdominal aorta, with a high mortality rate when rupturing. Although lots of piRNA pathway genes (piRPGs) have recently been linked to both neoplastic and non-neoplastic illnesses, their role in AAA is still unknown. Utilizing integrative bioinformatics methods, this research discovered piRPGs as biomarkers for AAA and explore possible molecular mechanisms.

METHODS

The datasets were obtained from the Gene Expression Omnibus and piRPGs were identified from the Genecards database. The "limma" and "clusterProfiler" R-packages were used to discover differentially expressed genes and perform enrichment analysis, respectively. Hub piRPGs were further filtered using least absolute shrinkage and selection operator regression, random forests, as well as receiver operating characteristic curve. Additionally, multi-factor logistic regression (MLR), extreme gradient boosting (XGboost), and artificial neural network (ANN) were employed to construct prediction models. The relationship between hub piRPGs and immune infiltrating cells and sgGSEA were further studied. The expression of hub piRPGs was verified by qRT-PCR, immunohistochemistry, and western blotting in AAA and normal vascular tissues and analyzed by scRNA-seq in mouse AAA model. SRAMP and cMAP database were utilized for the prediction of N6-methyladenosine (m6A) targets therapeutic drug.

RESULTS

34 differentially expressed piRPGs were identified in AAA and enriched in pathways of immune regulation and gene silence. Three piRPGs (PPP1R12B, LRP10, and COL1A1) were further screened as diagnostic genes and used to construct prediction model. Compared with MLR and ANN, Xgboost showed better predictive ability, and PPP1R12B might have the ability to distinguish small and large AAA. Furthermore, the expression levels of PPP1R12B and COL1A1 were consistent with the results of bioinformatics analysis, and PPP1R12B showed a downward trend that may be related to m6A.

CONCLUSION

The results suggest that piRPGs might serve a significant role in AAA. PPP1R12B, COL1A1, and LRP10 had potential as diagnostic-specific biomarkers for AAA and performed better in XGboost model. The expression and localization of PPP1R12B and COL1A1 were experimentally verified. Besides, downregulation of PPP1R12B caused by m6A might contribute to the formation of AAA.

Trends in AAA Repair in Australia Over Twenty Years

Background

The advent of endovascular techniques has revolutionised the treatment of abdominal aortic aneurysms (AAA). Many countries have seen a transition from open AAA repair (OAR) to endovascular AAA repair (EVAR) over the past 25 years. The only study done in Australia that describes this change was done in the private sector. Majority of healthcare in Australia is delivered through the public, universal healthcare system. The aim of this study was to evaluate the trends in AAA repair in the Australian public sector over the past two decades.

Methods

The Australian Institute of Health and Welfare (AIHW) Procedures Data Cubes from the National Hospitals Data Collection was used to extract data pertaining to AAA repairs from 2000 to 2021. Population data from the Australian Bureau of Statistics was used to calculate incidence of each type of repair per 100,000 population.

Results

There were 65,529 AAA repairs performed in the Australian public sector from 2000 to 2021. EVARs accounted for 64.4% (42,205) and OARs accounted for 35.6% (23, 324) of them. EVAR surpassed OAR as the preferred method of AAA repair in 2006. This trend was observed in both males and females and across all age groups.

Conclusion

There was a consistent and steady transition from OAR to EVAR over the 21 year period with EVAR surpassing OAR as the preferred method of AAA repair relatively early in Australia compared to other countries. Further research that investigates medium- and long-term outcomes of newer stent grafts is needed to further ascertain the continued viability and effectiveness of this trend in AAA treatment.

Cardiac risk after elective endovascular repair for infrarenal abdominal aortic aneurysm: Results from the Italian Collaborators for EVAR multicenter registry

OBJECTIVE

Major adverse cardiac events (MACEs) were common complications after endovascular aortic repair (EVAR) causing significant postoperative morbidity and mortality. The aim of the study was to evaluate the cardiac risk after elective EVAR for uncomplicated noninfected infrarenal abdominal aortic aneurysm in a large multicenter cohort.

METHODS

This is a multicenter, retrospective, financially unsupported physician-initiated observational cohort study conducted by four academic tertiary referral hospitals from January 2018 to March 2021. Baseline, perioperative, and postoperative information of elective EVARs was evaluated. The primary outcome was the incidence of MACEs after EVAR, which was defined as acute coronary syndrome, non-ST-elevation myocardial infarction, unstable angina pectoris, de novo atrial fibrillation, hospitalization for heart failure, and revascularization as well as cardiovascular death. Secondary outcomes were 1-year overall survival (all-cause mortality) and freedom from aorta-related mortality. Comparative analysis was conducted between MACE and overall population, and univariate and multivariate logistic regression analyses were used to analyze factors associated with the risk of the MACE occurrence and early 1-year mortality.

RESULTS

The study has enrolled 497 patients (35 females, 7%) with a mean age of 75.3 ± 7.8 years. The MACE rate was 6.4% (32/497, events/patients), and the majority of the events were recorded in the postoperative period (24/32, 75%; overall 24/497, 4.8%). One-year survival from all-cause mortality was 94% (95% confidence interval [CI]: 91-96), and the MACE population showed a significantly lower survival estimation rate (Overall - MACEs, 95.8% [95% CI: 93-97] - 67.9% [95% CI: 47-82], log-rank 41.950, P = .0001). Freedom from aorta-related mortality was 99.3% (95% CI: 98-100). The perioperative need for red blood cell transfusions was strongly related to the MACE occurrence (odds ratio: 2.67, 95% CI: 1.52-4.68, P = .001) and 1-year mortality (hazard ratio: 2.14, 95% CI: 1.48-3.09, P = .0001).

CONCLUSIONS

MACEs represent a common complication in the postoperative and early period after elective EVAR. Blood loss requiring red blood cell transfusions is associated with increased postoperative MACEs and early mortality, suggesting that all the efforts should be carried out to reduce the bleeding during and after elective interventions.

The effect of exercise training intervention for patients with abdominal aortic aneurysm on cardiovascular and cardiorespiratory variables: an updated meta-analysis of randomized controlled trials

OBJECTIVE

The purpose of this meta-analysis was to evaluate the effect of exercise training intervention in patients with abdominal aortic aneurysm (AAA).

METHODS

Eight randomized controlled trials (RCTs) that recruited 588 AAA patients were extracted using 4 databases (PubMed, Embase, Wanfang Data, and Cochrane Library). Physiological and biochemistry parameters that included in this study are high-sensitivity C-reactive protein (hs-CRP), respiratory peak oxygen uptake rate (VO2peak), triglyceride (TG), total cholesterol (TC), anaerobic threshold (AT), the diameter of AAA, high density lipoprotein cholesterol (HDL), low density lipoprotein cholesterol (LDL), and matrix metalloproteinase-9 (MMP-9). Standard mean difference (SMD) was used to assess the between group effect.

RESULTS

This meta-analysis was synthesized with findings from RCTs and found that hs-CRP (SMD, - 0.56 mg/dL; 95% CI: - 0.90 to 0.22; P = 0.001), VO2peak (SMD, 0.4 mL/kg/min; 95% CI, 0.21 to 0.60; P < 0.001), TG (SMD, - 0.39 mg/dL; 95% CI: - 0.02 to 0.77; P = 0.04), and AT (SMD, 0.75 mL/kg/min; 95% CI, 0.54 to 0.96; P < 0.001) were significantly improved in the exercise groups, while the size of AAA (SMD, - 0.15; 95% CI: - 0.36 to 0.06; P = 0.15), TC (SMD, 0.16 mg/dL; 95% CI: - 0.10 to 0.42; P = 0.23), HDL/LDL ratio (SMD, - 0.06; 95% CI: - 0.32 to 0.20; P = 0.64), HDL (SMD, - 0.09; 95% CI: - 0.39 to 0.20; P = 0.54), LDL (SMD, 0.08; 95% CI: - 0.21 to 0.38; P = 0.59), and MMP-9 (SMD, - 0.23 mg/dL; 95% CI: - 0.53 to 0.06; P = 0.12) did not differ in the exercise groups compared with the controls.

CONCLUSION

Exercise intervention improved some of the CVD risk factors but not all, hs-CRP, VO2peak and AT were significantly improved after exercise intervention, while, changes of MMP-9, the size of AAA, and the overall lipids profile were not. Exercise intervention provides an additional solution for improving cardiorespiratory capacity and health status among AAA patients, and might lead to a delay of AAA progression.

Quality Assessment of Elective Abdominal Aortic Aneurysm Repair Patient Information on the Internet Using the Modified Ensuring Quality Information for Patients Tool

OBJECTIVE

This study aimed to assess the quality of patient information material regarding elective abdominal aortic aneurysm (AAA) repair on the internet using the Modified Ensuring Quality Information for Patients (MEQIP) tool.

METHODS

A qualitative assessment of internet based patient information was performed. The 12 most used search terms relating to AAA repair were identified using Google Trends, with the first 10 pages of websites retrieved for each term searched. Duplicates were removed, and information for patients undergoing elective AAA were selected. Further exclusion criteria were marketing material, academic journals, videos, and non-English language sites. The remaining websites were then MEQIP scored independently by two reviewers, producing a final score by consensus.

RESULTS

A total of 1 297 websites were identified, with 235 (18.1%) eligible for analysis. The median MEQIP score was 18 (interquartile range [IQR] 14, 21) out of a possible 36. The highest score was 33. The 99th percentile MEQIP scoring websites scored > 27, with four of these six sites representing online copies of hospital patient information leaflets, however hospital sites overall had lower median MEQIP scores than most other institution types. MEQIP subdomain median scores were: content, 8 (IQR 6, 11); identification, 3 (IQR 1, 3); and structure, 7 (IQR 6, 9). Of the analysed websites, 77.9% originated from the USA (median score 17) and 12.8% originated in the UK (median score 22). Search engine ranking was related to website institution type but had no correlation with MEQIP.

CONCLUSION

When assessed by the MEQIP tool, most websites regarding elective AAA repair are of questionable quality. This is in keeping with studies in other surgical and medical fields. Search engine ranking is not a reliable measure of quality of patient information material regarding elective AAA repair. Health practitioners should be aware of this issue as well as the whereabouts of high quality material to which patients can be directed.

Hypoxia inducible factor 1-alpha in the pathogenesis of abdominal aortic aneurysms in vivo: A narrative review

Abdominal aortic aneurysms (AAAs) are relatively common, primarily among older men, and, in the case of rupture, are associated with high mortality. Although procedure-related morbidity and mortality have improved with the advent of endovascular repair, noninvasive treatment and improved assessment of AAA rupture risk should still be sought. Several cellular pathways seem contributory to the histopathologic changes that drive AAA growth and rupture. Hypoxia inducible factor 1-alpha (HIF-1α) is an oxygen-sensitive protein that accumulates in the cytoplasm under hypoxic conditions and regulates a wide array of downstream effectors to hypoxia. Examining the potential role of HIF-1α in the pathogenesis of AAAs is alluring, because local hypoxia is known to be present in the AAA vessel wall. A systematic scoping review was performed to review the current evidence regarding the role of HIF-1α in AAA disease in vivo. After screening, 17 studies were included in the analysis. Experimental animal studies and human studies show increased HIF-1α activity in AAA tissue compared with healthy aorta and a correlation of HIF-1α activity with key histopathologic features of AAA disease. In vivo HIF-1α inhibition in animals protects against AAA development and growth. One study reveals a positive correlation between HIF-1α-activating genetic polymorphisms and the risk of AAA disease in humans. The main findings suggest a causal role of HIF-1α in the pathogenesis of AAAs in vivo. Further research into the HIF-1α pathway in AAA disease might reveal clinically applicable pharmacologic targets or biomarkers relevant in the treatment and monitoring of AAA disease.

Modern management of ruptured abdominal aortic aneurysm

Ruptured abdominal aortic aneurysms (rAAA) remain one of the most clinically challenging and technically complex emergencies in contemporary vascular surgery practice. Over the past 30 years, a variety of changes surrounding the treatment of rAAA have evolved including improvements in diagnosis, development of coordinated referral networks to transfer patients more efficiently to higher volume centers, deliberate de-escalation of pre-hospital resuscitation, modification of patient and procedure selection, implementation of clinical pathways, as well as enhanced awareness of certain high-impact postoperative complications. Despite these advances, current postoperative outcomes remain sobering since morbidity and mortality rates ranging from 25%-50% persist among modern published series. Some of the most impactful variation in rAAA management has been fostered by the rapid proliferation of endovascular repair (EVAR) along with service alignment at selected centers to improve timely revascularization. Indeed, clinical care pathways and emergency response networks are now increasingly utilized which has led to improved outcomes contemporaneously. Moreover, evolution in pre- and post-operative physiologic resuscitation has also contributed to observed improvements in rAAA outcomes. Due to different developments in care provision over time, the purpose of this review is to describe the modern management of rAAA, while providing historical perspectives on patient, procedure and systems-based practice elements that have evolved care delivery paradigms in this complex group of patients.

Integrated particle image velocimetry and fluid-structure interaction analysis for patient-specific abdominal aortic aneurysm studies

BACKGROUND

Understanding the hemodynamics of an abdominal aortic aneurysm (AAA) is crucial for risk assessment and treatment planning. This study introduces a low-cost, patient-specific in vitro AAA model to investigate hemodynamics using particle image velocimetry (PIV) and flow-simulating circuit, validated through fluid-structure interaction (FSI) simulations.

METHODS

In this study, 3D printing was employed to manufacture a flexible patient-specific AAA phantom using a lost-core casting technique. A pulsatile flow circuit was constructed using off-the-shelf components. A particle image velocimetry (PIV) setup was built using an affordable laser source and global shutter camera, and finally, the flow field inside the AAA was analyzed using open-source software. Fluid-structure interaction (FSI) simulations were performed to enhance our understanding of the flow field, and the results were validated by PIV analysis. Both steady-state and transient flow conditions were investigated.

RESULTS

Our experimental setup replicated physiological conditions, analyzing arterial wall deformations and flow characteristics within the aneurysm. Under constant flow, peak wall deformations and flow velocities showed deviations within - 12% to + 27% and - 7% to + 5%, respectively, compared to FSI simulations. Pulsatile flow conditions further demonstrated a strong correlation (Pearson coefficient 0.85) in flow velocities and vectors throughout the cardiac cycle. Transient phenomena, particularly the formation and progression of vortex structures during systole, were consistently depicted between experimental and numerical models.

CONCLUSIONS

By bridging high-fidelity experimental observations with comprehensive computational analyses, this study underscores the potential of integrated methodologies in enhancing our understanding of AAA pathophysiology. The convergence of realistic AAA phantoms, precise PIV measurements at affordable cost point, and validated FSI models heralds a new paradigm in vascular research, with significant implications for personalized medicine and bioengineering innovations.

Deep Learning-Based Intraoperative Stent Graft Segmentation on Completion Digital Subtraction Angiography During Endovascular Aneurysm Repair

PURPOSE

Modern endovascular hybrid operating rooms generate large amounts of medical images during a procedure, which are currently mostly assessed by eye. In this paper, we present fully automatic segmentation of the stent graft on the completion digital subtraction angiography during endovascular aneurysm repair, utilizing a deep learning network.

TECHNIQUE

Completion digital subtraction angiographies (cDSAs) of 47 patients treated for an infrarenal aortic aneurysm using EVAR were collected retrospectively. A two-dimensional convolutional neural network (CNN) with a U-Net architecture was trained for segmentation of the stent graft from the completion angiographies. The cross-validation resulted in an average Dice similarity score of 0.957 ± 0.041 and median of 0.968 (IQR: 0.950 - 0.976). The mean and median of the average surface distance are 1.266 ± 1.506 mm and 0.870 mm (IQR: 0.490 - 1.430), respectively.

CONCLUSION

We developed a fully automatic stent graft segmentation method based on the completion digital subtraction angiography during EVAR, utilizing a deep learning network. This can provide the platform for the development of intraoperative analytical applications in the endovascular hybrid operating room such as stent graft deployment accuracy, endoleak visualization, and image fusion correction.

Familial Mediterranean fever and microRNAs

Familial Mediterranean fever (FMF) is an inherited disorder caused by the gain of function mutations in MEFV (MEditerranean FeVer) gene loci. FMF affects more than 100,000 people worldwide and generally seen in the eastern Mediterranean region and causes the lifelong diseases which have a significant effect on the patient's life quality and health systems. The identification of low penetrant or heterozygous MEFV gene mutations in clinically diagnosed FMF patients was considered that epigenetic or environmental factors may display a role in FMF pathogenesis. Epigenetics might be defined as heritable changes that affect gene expression without any changes in the genome. MicroRNAs (miRNAs) are the main group of small noncoding RNAs, and an important element of epigenetic mechanisms and their discoveries revolutionized our knowledge about biological processes, such as malignant, infectious and autoimmune mechanisms, and contributed to the development of the epigenetic areas. In this review, the studies focusing on the roles of miRNAs in FMF pathogenesis in the last decades were examined and the importance of miRNAs as therapeutic agents which are promising for diagnosis and treatment was discussed.

A Single Centre Long Term Follow Up of the Nellix Endovascular Aneurysm Sealing System

OBJECTIVE

To evaluate the clinical performance at long term follow up of endovascular aneurysm sealing (EVAS, Endologix Inc. Nellix, Irvine, CA, USA) in the treatment of abdominal aortic aneurysm (AAA).

METHODS

Observational, prospective, single centre study of primary AAA interventions with EVAS (n = 117) from November 2013 to November 2016. Endpoints were primary technical success, Nellix device failure, freedom from open surgical conversion (OSC), freedom from secondary intervention, sac rupture, total mortality, and aneurysm related mortality at long term follow up.

RESULTS

The median age was 75 years (interquartile range [IQR] 70, 81 years) and 83% were male. The median AAA diameter was 58 mm (IQR 54, 60 mm). The median length of follow up was 6.2 years (IQR 5.6, 6.8 years). Primary technical success was 100%. Median time to Nellix failure was 5.6 years (IQR 3.3, 7.4 years). Freedom from Nellix failure at five and seven years was 54% (95% confidence interval [CI] 54.2 - 63.8%) and 36% (95% CI 22.3 - 49.7%), respectively. Freedom from OSC at five and seven years was 63% (95% CI 53.2 - 72.8%) and 59% (95% CI 47 - 71%), respectively. The secondary intervention rate was 11.4/100 person years. Freedom from secondary intervention at five and seven years was 52% (95% CI 42.2 - 61.8%) and 51% (95% CI 41.2 - 60.8%), respectively. The cumulative mortality rate at five and seven years was 36% and 54%, respectively. Secondary sac rupture occurred in 9.4% (11/117) with a rate of 2/100 person years. Aneurysm related mortality was 12% (14/117) with a rate of 2.5/100 person years. The median survival was four years (IQR 3, 5.6 years). Thirty day mortality for acute OSC was 67% (n = 3) and 17.1% (6/35) for elective OSC.

CONCLUSION

Long term follow up showed an increased failure rate. Diligent surveillance after endovascular AAA treatment is mandatory, especially when promising new devices are put into clinical use.

Simultaneous surgery of an inflammatory abdominal aortic aneurysm and renal cell carcinoma: A case report

INTRODUCTION

Abdominal aortic aneurysm (AAA) and renal cell carcinoma (RCC) coincidence is considered a rare phenomenon. Moreover, the inflammatory nature of aneurysm increases the rarity of the case.

PRESENTATION OF CASE

Our case was a 66-year-old man complaining of constant abdominal pain with a periumbilical pulsatile mass on examination. The computerized tomography angiography revealed a 67*41*44 mm AAA and a 52*43 mm renal mass.

CLINICAL DISCUSSION

Not only choosing the most appropriate treatment is critical when two life-threatening diseases coexist in the same patient but also avoiding from any injury to adjacent organs while releasing fibrotic adhesions due to inflammatory process makes the case more challenging.

CONCLUSION

The preset study describes the successful one-stage and open surgery for treatment of simultaneous IAAA and RCC.

3D-Ultrasound Based Mechanical and Geometrical Analysis of Abdominal Aortic Aneurysms and Relationship to Growth

The heterogeneity of progression of abdominal aortic aneurysms (AAAs) is not well understood. This study investigates which geometrical and mechanical factors, determined using time-resolved 3D ultrasound (3D + t US), correlate with increased growth of the aneurysm. The AAA diameter, volume, wall curvature, distensibility, and compliance in the maximal diameter region were determined automatically from 3D + t echograms of 167 patients. Due to limitations in the field-of-view and visibility of aortic pulsation, measurements of the volume, compliance of a 60 mm long region and the distensibility were possible for 78, 67, and 122 patients, respectively. Validation of the geometrical parameters with CT showed high similarity, with a median similarity index of 0.92 and root-mean-square error (RMSE) of diameters of 3.5 mm. Investigation of Spearman correlation between parameters showed that the elasticity of the aneurysms decreases slightly with diameter (p = 0.034) and decreases significantly with mean arterial pressure (p < 0.0001). The growth of a AAA is significantly related to its diameter, volume, compliance, and surface curvature (p < 0.002). Investigation of a linear growth model showed that compliance is the best predictor for upcoming AAA growth (RMSE 1.70 mm/year). To conclude, mechanical and geometrical parameters of the maximally dilated region of AAAs can automatically and accurately be determined from 3D + t echograms. With this, a prediction can be made about the upcoming AAA growth. This is a step towards more patient-specific characterization of AAAs, leading to better predictability of the progression of the disease and, eventually, improved clinical decision making about the treatment of AAAs.

Enhancement of Classifier Performance Using Swarm Intelligence in Detection of Diabetes from Pancreatic Microarray Gene Data

In this study, we focused on using microarray gene data from pancreatic sources to detect diabetes mellitus. Dimensionality reduction (DR) techniques were used to reduce the dimensionally high microarray gene data. DR methods like the Bessel function, Discrete Cosine Transform (DCT), Least Squares Linear Regression (LSLR), and Artificial Algae Algorithm (AAA) are used. Subsequently, we applied meta-heuristic algorithms like the Dragonfly Optimization Algorithm (DOA) and Elephant Herding Optimization Algorithm (EHO) for feature selection. Classifiers such as Nonlinear Regression (NLR), Linear Regression (LR), Gaussian Mixture Model (GMM), Expectation Maximum (EM), Bayesian Linear Discriminant Classifier (BLDC), Logistic Regression (LoR), Softmax Discriminant Classifier (SDC), and Support Vector Machine (SVM) with three types of kernels, Linear, Polynomial, and Radial Basis Function (RBF), were utilized to detect diabetes. The classifier's performance was analyzed based on parameters like accuracy, F1 score, MCC, error rate, FM metric, and Kappa. Without feature selection, the SVM (RBF) classifier achieved a high accuracy of 90% using the AAA DR methods. The SVM (RBF) classifier using the AAA DR method for EHO feature selection outperformed the other classifiers with an accuracy of 95.714%. This improvement in the accuracy of the classifier's performance emphasizes the role of feature selection methods.

The relationship between computed tomography-derived body composition, systemic inflammation, and survival in patients with abdominal aortic aneurysm

OBJECTIVE

Patient selection and risk stratification for elective repair of abdominal aortic aneurysm (AAA), either by open surgical repair or by endovascular aneurysm repair, remain challenging. Computed tomography (CT)-derived body composition analysis (CT-BC) and systemic inflammation-based scoring systems such as the systemic inflammatory grade (SIG) appear to offer prognostic value in patients with AAA undergoing endovascular aneurysm repair. The relationship between CT-BC, systemic inflammation, and prognosis has been explored in patients with cancer, but data in noncancer populations are lacking. The present study aimed to examine the relationship between CT-BC, SIG, and survival in patients undergoing elective intervention for AAA.

METHODS

A total of 611 consecutive patients who underwent elective intervention for AAA at three large tertiary referral centers were retrospectively recruited for inclusion into the study. CT-BC was performed and analyzed using the CT-derived sarcopenia score (CT-SS). Subcutaneous and visceral fat indices were also recorded. SIG was calculated from preoperative blood tests. The outcomes of interest were overall and 5-year mortality.

RESULTS

Median (interquartile range) follow-up was 67.0 (32) months, and there were 194 (32%) deaths during the follow-up period. There were 122 (20%) open surgical repair cases, 558 (91%) patients were male, and the median (interquartile range) age was 73.0 (11.0) years. Age (hazard ratio [HR]: 1.66, 95% confidence interval [CI]: 1.28-2.14, P < .001), elevated CT-SS (HR: 1.58, 95% CI: 1.28-1.94, P < .001), and elevated SIG (HR: 1.29, 95% CI: 1.07-1.55, P < .01) were independently associated with increased hazard of mortality. Mean (95% CI) survival in the CT-SS 0 and SIG 0 subgroup was 92.6 (84.8-100.4) months compared with 44.9 (30.6-59.2) months in the CT-SS 2 and SIG ≥2 subgroup (P < .001). Patients with CT-SS 0 and SIG 0 had 90% (standard error: 4%) 5-year survival compared with 34% (standard error: 9%) in patients with CT-SS 2 and SIG ≥2 (P < .001).

CONCLUSIONS

Combining measures of radiological sarcopenia and the systemic inflammatory response offers prognostic value in patients undergoing elective intervention for AAA and may contribute to future clinical risk predication strategies.

National Institutes of Health funding among vascular surgeons is rare

BACKGROUND

The National Institutes of Health (NIH) is an essential source of funding for vascular surgeons conducting research. NIH funding is frequently used to benchmark institutional and individual research productivity, help determine eligibility for academic promotion, and as a measure of scientific quality. We sought to appraise the current scope of NIH funding to vascular surgeons by appraising the characteristics of NIH-funded investigators and projects. In addition, we also sought to determine whether funded grants addressed recent Society for Vascular Surgery (SVS) research priorities.

METHODS

In April 2022, we queried the NIH Research Portfolio Online Reporting Tools Expenditures and Results (RePORTER) database for active projects. We only included projects that had a vascular surgeon as a principal investigator. Grant characteristics were extracted from the NIH Research Portfolio Online Reporting Tools Expenditures and Results database. Principal investigator demographics and academic background information were identified by searching institution profiles.

RESULTS

There were 55 active NIH awards given to 41 vascular surgeons. Only 1% (41/4037) of all vascular surgeons in the United States receive NIH funding. Funded vascular surgeons are an average of 16.3 years out of training; 37% (n = 15) are women. The majority of awards (58%; n = 32) were R01 grants. Among the active NIH-funded projects, 75% (n = 41) are basic or translational research projects, and 25% (n = 14) are clinical or health services research projects. Abdominal aortic aneurysm and peripheral arterial disease are the most commonly funded disease areas and together accounted for 54% (n = 30) of projects. Three SVS research priorities are not addressed by any of the current NIH-funded projects.

CONCLUSIONS

NIH funding of vascular surgeons is rare and predominantly consists of basic or translational science projects focused on abdominal aortic aneurysm and peripheral arterial disease research. Women are well-represented among funded vascular surgeons. Although the majority of SVS research priorities receive NIH funding, three SVS research priorities are yet to be addressed by NIH-funded projects. Future efforts should focus on increasing the number of vascular surgeons receiving NIH grants and ensuring all SVS research priorities receive NIH funding.

Identification and experimental validation of autophagy-related genes in abdominal aortic aneurysm

AIM

Autophagy plays essential roles in abdominal aortic aneurysm (AAA) development and progression. The objective of this study was to verify the autophagy-related genes (ARGs) underlying AAA empirically and using bioinformatics analysis.

METHODS

Two gene expression profile datasets GSE98278 and GSE57691 were downloaded from the Gene Expression Omnibus (GEO) database, and principal component analysis was performed. Following, the R software (version 4.0.0) was employed to analyze potentially differentially expressed genes related with AAA and autophagy. Subsequently, the candidate genes were screened using protein-protein interaction (PPI), gene ontology (GO) enrichment analysis, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Finally, quantitative real-time polymerase chain reaction (RT-qPCR) was performed to detect the RNA expression levels of the top five selected abnormal ARGs in clinical samples obtained from the normal and AAA patients.

RESULTS

According to the information contained (97 AAA patients and 10 healthy controls) in the two datasets, a total of 44 differentially expressed autophagy-related genes (6 up-regulated genes and 38 down-regulated genes) were screened. GO enrichment analysis of differentially expressed autophagy-related genes (DEARGs) demonstrated that some enrichment items were associated with inflammation, and PPI analysis indicated interaction between these genes. RT-qPCR results presented that the expression levels of IL6, PPARG, SOD1, and MAP1LC3B were in accordance with the bioinformatics prediction results acquired from the mRNA chip.

CONCLUSION

Bioinformatics analysis identified 44 potential autophagy-related differentially expressed genes in AAA. Further verification by RT- qPCR presented that IL6, PPARG, SOD1, and MAP1LC3B may affect the development of AAA by regulating autophagy. These findings might help explain the pathogenesis of AAA and be helpful in its diagnosis and treatment.

Dosimetric comparison and evaluation of two computational algorithms in VMAT treatment plans

PURPOSE

This study aimed to assess the accuracy and dosimetric impact of the Acuros XB (AXB) algorithm compared to the Anisotropic Analytical Algorithm (AAA) in two situations. First, simple phantom geometries were set and analyzed; moreover, volumetric modulated arc therapy (VMAT) clinical plans for Head & Neck and lung cases were calculated and compared.

METHODS

First, a phantom study was performed to compare the algorithms with radiochromic EBT3 film doses using one PMMA slab phantom and two others containing foam or air gap. Subsequently, a clinical study was conducted, including 20 Head & Neck and 15 lung cases irradiated with the VMAT technique. The treatment plans calculated by AXB and AAA were evaluated in terms of planning target volume (PTV) coverage (V95% ), dose received by relevant organs at risk (OARs), and the impact of using AXB with a grid size of 1 mm. Finally, patient-specific quality assurance (PSQA) was performed and compared for 17 treatment plans.

RESULTS

Phantom dose calculations showed a better agreement of AXB with the film measurements. In the clinical study, AXB plans exhibited lower Conformity Index and PTV V95% , higher maximum PTV dose, and lower mean and minimum PTV doses for all anatomical sites. The most notable differences were detected in regions of intense heterogeneity. AXB predicted lower doses for the OARs, while the calculation time with a grid size of 1 mm was remarkably higher. Regarding PSQA, although AAA was found to exhibit slightly higher gamma passing rates, the difference did not affect the AXB treatment plan quality.

CONCLUSIONS

AXB demonstrated higher accuracy than AAA in dose calculations of both phantom and clinical conditions, specifically in interface regions, making it suitable for sites with large heterogeneities. Hence, such dosimetric differences between the two algorithms should always be considered in clinical practice.

Low-volume surgeons can have better outcomes at certain hospital settings for open abdominal aortic repairs

OBJECTIVE

The volume-outcomes relationship is cross-cutting among open abdominal aortic operations, where higher-volume surgeons have better perioperative outcomes. However, there has been minimal focus on low-volume surgeons and how to improve their outcomes. This study sought to identify if there are any differences in outcomes among low-volume surgeons for open abdominal aortic surgeries by different hospital settings.

METHODS

We used the 2012-2019 Vascular Quality Initiative registry to identify all patients who underwent open abdominal aortic surgery for aneurysmal or aorto-iliac occlusive disease by a low-volume surgeon (<7 operations annually). We categorized high-volume hospitals using three distinct definitions: those that performed ≥10 operations annually, those with at least one high-volume surgeon, and by the number of surgeons (1-2 surgeons, 3-4 surgeons, 5-7 surgeons, and 8+ surgeons). Outcomes included 30-day perioperative mortality, overall complications, and failure-to-rescue. We compared outcomes among low-volume surgeons using univariable and multivariable logistic regressions across each of these three hospital categorizations.

RESULTS

Among 14,110 patients who underwent open abdominal aortic surgery, 10,252 (7 3%) were performed by 1155 low-volume surgeons. Two-thirds of these patients (66%) underwent their surgery at a high-volume hospital, fewer than one-third (30%) at a hospital that had at least one high-volume surgeon, and one-half (49%) at hospitals with at least five surgeons. Among all patients operated on by low-volume surgeons, rates of 30-day mortality were 3.8%, perioperative complications were 35.3%, and failure-to-rescue were 9.9%. Low-volume surgeons operating at high-volume hospitals for aneurysmal disease had lower rates of perioperative death (adjusted odds ratio [aOR], 0.66; 95% confidence interval [CI], 0.48-0.90) and failure-to-rescue (aOR, 0.70; 95% CI, 0.50-0.98), but similar rates of complications (aOR, 1.06; 95% CI, 0.89-1.27). Similarly, patients undergoing their operation at hospitals that had at least one high-volume surgeon had lower rates of death (aOR, 0.71; 95% CI, 0.50-0.99) for aneurysmal disease. Patient outcomes among low-volume surgeons for aorto-iliac occlusive disease did not vary by hospital setting.

CONCLUSIONS

The majority of patients undergoing open abdominal aortic surgery have a low-volume surgeon, where outcomes are slightly better for those taking place at a high-volume hospital. Focused and incentivized interventions may be needed to improve outcomes among low-volume surgeons across all practice settings.

The prognostic value of preoperative systemic inflammation-based scoring in patients undergoing endovascular repair of abdominal aortic aneurysm

OBJECTIVE

Abdominal aortic aneurysm (AAA) is a common condition that is predominantly managed in the United Kingdom by endovascular aneurysm repair (EVAR). Activation of the systemic inflammatory response (SIR) appears to offer prognostic value in patients with vascular disease. The present study examines the relationship between the SIR and survival in patients undergoing standard and complex endovascular aneurysm repair (EVAR and fenestrated/branched [F/B]-EVAR).

METHODS

Consecutive patients undergoing elective EVAR and F/B-EVAR were retrospectively identified from three tertiary vascular centers over a 5-year period. Neutrophil:lymphocyte ratio and modified Glasgow Prognostic Score were calculated from preoperative blood results and combined into the systemic inflammatory grade (SIG). The primary outcome was all-cause mortality during the follow-up period, which was compared between subgroups of SIGs.

RESULTS

There were 506 patients included in the final study, with a median follow-up of 68.0 months (interquartile range, 27.3 months), and there were 163 deaths during the follow-up period. Mean survival in the SIG 0 vs SIG 1 vs SIG 2 vs SIG 3 vs SIG 4 subgroups was 80.7 months (95% confidence interval [CI], 76.5-85.0 months) vs 78.7 months (95% CI, 72.7-84.7 months) vs 61.0 months (95% CI, 51.1-70.8 months) vs 65.1 months (95% CI, 45.0-85.2 months) vs 54.9 months (95% CI, 34.4-75.3 months) (P < .05). In the entire cohort, age (P < .001), body mass index (P < .05), high creatinine (P < .05), and SIG (P < .05) were associated with survival on univariate analysis, with retained independent association for age (hazard ratio, 1.72; 95% CI, 1.29-2.31; P < .001) and SIG (hazard ratio, 1.20; 95% CI, 1.02-1.40; P < .05) on multivariate analysis. Increasing SIG (area under the curve, 0.68; 95% CI, 0.58-0.78; P < .01) predicted 1-year mortality.

CONCLUSIONS

Markers of the SIR such the SIG may be used to identify patients at higher risk of adverse outcome in patients undergoing EVAR and F/B-EVAR for abdominal aortic aneurysms. These findings warrant further investigation in large prospective cohort studies.

Evaluation of the prognostic value of computed tomography-derived body composition in patients undergoing endovascular aneurysm repair

BACKGROUND

Endovascular aneurysm repair (EVAR) is the most common mode of repair of abdominal aortic aneurysms (AAA) in the UK. EVAR ranges from standard infrarenal repair to complex fenestrated and branched EVAR (F/B-EVAR). Sarcopenia is defined by lower muscle mass and function, which is associated with inferior perioperative outcomes. Computed tomography-derived body composition analysis offers prognostic value in patients with cancer. Several authors have evaluated the role of body composition analysis in predicting outcomes in patients undergoing EVAR; however, the evidence base is limited by heterogeneous methodology.

METHODS

Six hundred seventy-four consecutive patients (58 (8.6%) female, mean (SD) age 74.4 (6.8) years) undergoing EVAR and F/B-EVAR at three large tertiary centres were retrospectively recruited. Subcutaneous and visceral fat indices (SFI and VFI), psoas and skeletal muscle indices, and skeletal muscle density were measured at the L3 vertebral level from pre-operative computed tomographies. The maximally selected rank statistic technique was used to define optimal thresholds to predict mortality.

RESULTS

There were 191 deaths during the median follow-up period of 60.0 months. Mean (95% CI) survival in the low SMI versus high SMI subgroups was 62.6 (58.5-66.7) versus 82.0 (78.7-85.3) months (P < 0.001). Mean (95% CI) survival in the low SFI versus high SFI subgroups was 56.4 (48.2-64.7) versus 77.1 (74.2-80.1) months (P < 0.001). One-year mortality in the low SMI versus high SMI subgroups was 10% versus 3% (P < 0.001). Low SMI was associated with increased odds of one-year mortality (OR 3.19, 95% CI 1.60-6.34, P < 0.001). Five-year mortality in the low SMI versus high SMI subgroups was 55% versus 28% (P < 0.001). Low SMI was associated with increased odds of five-year mortality (OR 1.54, 95% CI 1.11-2.14, P < 0.01). On multivariate analysis of all patients, low SFI (HR 1.90, 95% CI 1.30-2.76, P < 0.001) and low SMI (HR 1.88, 95% CI 1.34-2.63, P < 0.001) were associated with poorer survival. On multivariate analysis of asymptomatic AAA patients, low SFI (HR 1.54, 95% CI 1.01-2.35, P < 0.05) and low SMI (HR 1.71, 95% CI 1.20-2.42, P < 0.01) were associated with poorer survival.

CONCLUSIONS

Low SMI and SFI are associated with poorer long-term survival following EVAR and F/B-EVAR. The relationship between body composition and prognosis requires further evaluation, and external validation of the thresholds proposed in patients with AAA is required.

Shared Decision Making and the Management of Intact Abdominal Aortic Aneurysm: A Scoping Review of the Literature

OBJECTIVE

The aim of this study was to summarise the current knowledge of shared decision making (SDM) in patients facing a treatment decision about an intact abdominal aortic aneurysm (AAA), and to identify where further evidence is needed.

DATA SOURCES

MEDLINE, Embase, and the Cochrane Library were searched on 18 July 2021. An updated search was run on 31 May 2022 for relevant studies published from 1 January 2000 to 31 May 2022.

REVIEW METHODS

This scoping review was undertaken in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines following a pre-defined protocol, retrieving studies reporting on aspects of SDM in those with intact AAAs. Qualitative synthesis of the articles was performed, and the results grouped according to theme.

RESULTS

Fifteen articles reporting on a total of 1 344 participants (age range 62-74 years) from hospital vascular surgery clinics with intact AAAs were included. Studies were observational (n = 9), non-randomised studies of an intervention (n = 3), and randomised clinical trials (n = 3). The first theme was the preferences and practice of SDM. The proportion of patients preferring SDM ranged from 58% to 95% (three studies), although objective rating of SDM practice was consistently < 50% (three studies). Clinician training improved SDM practice. The second theme was poor provision of information. Fewer than half of patients (0 - 46%) surveyed were informed about all available treatment options (three studies). Publicly available information sources were rated as poor. The third theme concerned the utility of decision making support tools (DSTs). Two randomised trials demonstrated that the provision of DSTs improves patient knowledge and agreement between patient preference and repair type received but not objective measures of SDM for patients with AAAs.

CONCLUSION

SDM for patients with an intact AAA appears to be in its infancy. Most patients with an AAA want SDM, but this is not commonly applied. Most patients with an AAA do not receive adequate information for SDM, although the use of bespoke DSTs leaves patients better informed to facilitate SDM.

Abdominal aortic aneurysm volume and relative intraluminal thrombus volume might be auxiliary predictors of rupture-an observational cross-sectional study

Objectives

The study aimed to identify differences and compare anatomical and biomechanical features between elective and ruptured abdominal aortic aneurysms (AAAs).

Methods

Data (clinical, anatomical, and biomechanical) of 98 patients with AAA, 75 (76.53%) asymptomatic (Group aAAA) and 23 (23.46%) ruptured AAA (Group rAAA), were prospectively collected and analyzed. Anatomical, morphological, and biomechanical imaging markers like peak wall stress (PWS) and rupture risk equivalent diameter (RRED), comorbid conditions, and demographics were compared between the groups. Biomechanical features were assessed by analysis of Digital Imaging and Communication in Medicine images by A4clinics (Vascops), and anatomical features were assessed by 3Surgery (Trimensio). Binary and multiple logistic regression analysis were used and adjusted for confounders. Accuracy was assessed using receiving operative characteristic (ROC) curve analysis.

Results

In a multivariable model, including gender and age as confounder variables, maximal aneurysm diameter [MAD, odds ratio (OR) = 1.063], relative intraluminal thrombus (rILT, OR = 1.039), and total aneurysm volume (TAV, OR = 1.006) continued to be significant predictors of AAA rupture with PWS (OR = 1.010) and RRED (OR = 1.031). Area under the ROC curve values and correct classification (cc) for the same parameters and the model that combines MAD, TAV, and rILT were measured: MAD (0.790, cc = 75%), PWS (0.713, cc = 73%), RRED (0.717, cc = 55%), TAV (0.756, cc = 79%), rILT (0.656, cc = 60%), and MAD + TAV + rILT (0.797, cc = 82%).

Conclusion

Based on our results, in addition to MAD, other important predictors of rupture that might be used during aneurysm surveillance are TAV and rILT. Biomechanical parameters (PWS, RRED) as valuable predictors should be assessed in prospective clinical trials. Similar studies on AAA smaller than 55 mm in diameter, even difficult to organize, would be of even greater clinical value.

Dosimetric Comparison between Acuros XB (AXB) and Anisotropic Analytical Algorithm (AAA) in Volumetric Modulated Arc Therapy

AIM

Dose calculation accuracy between Anisotropic Analytical Algorithm (AAA) and Acuros XB (AXB) for various megavoltage (MV) photon beams for both flattening filter (FF) and flattening filter free (FFF) beams and to validate the accuracy of these dose calculations using inhomogeneous phantom in volumetric modulated arc therapy (VMAT).

MATERIAL AND METHODS

A Cheese Phantom having 20 holes that can be filled with all virtual water plugs or set of density calibration plugs  was used for VMAT planning using two different algorithms using either single or double arc. Further phantom was used  irradiate plan in linear accelerator and the point doses measured using a 0.053 cc A1SL ionization chamber along electrometer . Different plans, cylindrical shape, C-shaped and donut targets were planned 6MV, 10MV, 6FFF MV and 10FFF MV beam energy.

RESULT

The minimum average mean dose difference was 1.2% for PTV structures between AAA and AXB (p=0.02). Apart from these structures, the following density plugs have a more than 2% difference in maximum dose with statistical significance. (i) Solid water (MD=6.1%, p=0.016), (ii) Bone 200 (2.3%, p=0.029), (iii) CB_30% (MD=2.4%, p=0.050) and (iv) Cortical bone (MD=4.3%, p=0.018). In 6MV FFF and 10 MV FFF plans, the difference between AAA and AXB was not statistically significant (Fig 3). The Conformity index for the AAA less than that of AXB, in all energies and for all the PTVs. The CI was better in AXB than AAA, but the CI was not having much variation due to changes in beam energies, particularly for Cylinder shaped PTV.

CONCLUSION

All combinations of beam energy AAA showed higher values in the maximum dose than the Acuros XB, except for the lung insert. Nonetheless, AAA showed a higher mean dose than the Acuros XB. Differences between these two algorithms for most of the beam energies are minimal.

Considerations for radiotherapy planning with MV photons using dose-to-medium

Background and purpose

Radiotherapy planning considerations were developed for the previous calculation algorithms yielding dose to water-in-water (D_w,w). Advanced algorithms improve accuracy, but their dose values in terms of dose to medium-in-medium (D_m,m) depend on the medium considered. This work aimed to show how mimicking D_w,w planning with D_m,m can introduce new issues.

Materials and methods

A head and neck case involving bone and metal heterogeneities outside the CTV was considered. Two different commercial algorithms were used to obtain D_m,m and D_w,w distributions. First, a plan was optimised to irradiate the PTV uniformly and get a homogeneous D_w,w distribution. Second, another plan was optimised to achieve homogeneous D_m,m. Both plans were calculated with D_w,w and D_m,m, and the differences between their dose distributions, clinical impact, and robustness were evaluated.

Results

Uniform irradiation produced D_m,m cold spots in bone (-4%) and implants (-10%). Uniform D_m,m compensated them by increasing fluence but, when recalculated in D_w,w, the fluence compensations produced higher doses that affected homogeneity. Additionally, doses were 1% higher for the target, and + 4% for the mandible, thus increasing toxicity risk. Robustness was impaired when increased fluence regions and heterogeneities mismatched.

Conclusion

Planning with D_m,m as with D_w,w can impact clinical outcome and impair robustness. In optimisation, uniform irradiation instead of homogeneous D_m,m distributions should be pursued when media with different D_m,m responses are involved. However, this requires adapting evaluation criteria or avoiding medium effects. Regardless of the approach, there can be systematic differences in dose prescription and constraints.

The impact of neighborhood social disadvantage on abdominal aortic aneurysm severity and management

OBJECTIVE

Recent studies have highlighted socioeconomic disparities in the severity and management of abdominal aortic aneurysm (AAA) disease. However, these studies focus on individual measures of social disadvantage such as income and insurance status. The area deprivation index (ADI), a validated measure of neighborhood deprivation, provides a more comprehensive assessment of social disadvantage. Therefore, we examined the impact of ADI on AAA severity and its management.

METHODS

We identified all patients who underwent endovascular or open repair of an AAA in the Vascular Quality Initiative registry between 2003 and 2020. An ADI score of 1 to 100 was assigned to each patient based on their residential zip code, with higher ADI scores corresponding with increasing deprivation. Patients were categorized by ADI quintiles. Outcomes of interest included rates of ruptured AAA (rAAA) repair versus an intact AAA repair and rates of endovascular repair (EVAR) versus the open approach. Logistic regression was used to evaluate for an independent association between ADI quintile and these outcomes.

RESULTS

Among 55,931 patients who underwent AAA repair, 6649 (12%) were in the lowest ADI quintile, 11,692 (21%) in the second, 15,958 (29%) in the third, 15,035 (27%) in the fourth, and 6597 (12%) in the highest ADI quintile. Patients in the two highest ADI quintiles had a higher proportion of rAAA repair (vs intact repair) compared with those in the lowest ADI quintile (8.8% and 9.1% vs 6.2%; P < .001). They were also less likely to undergo EVAR (vs open approach) when compared with the lowest ADI quintile (81% and 81% vs 88%; P < .001). There was an overall trend toward increasing rAAA and decreasing EVAR rates with increasing ADI quintiles (P < .001). In adjusted analyses, when compared with patients in the lowest ADI quintile, patients in the highest ADI quintile had higher odds of rAAA repair (odds ratio, 1.4; 95% confidence interval, 1.2-1.8; P < .001) and lower odds of undergoing EVAR (odds ratio, 0.54; 95% confidence interval, 0.45-0.65; P < .001).

CONCLUSIONS

Among patients who underwent AAA repair in the Vascular Quality Initiative, those with higher neighborhood deprivation had significantly higher rates of rAAA repair (vs intact repair) and lower rates of EVAR (vs open approach). Further work is needed to better understand neighborhood factors that are contributing to these disparities to identify community-level targets for improvement.

Artificial Intelligence Outperforms Kaplan-Meier Analyses Estimating Survival after Elective Treatment of Abdominal Aortic Aneurysms

OBJECTIVE

Long term differences in survival after elective repair of abdominal aortic aneurysms (AAAs) between open surgical repair (OSR) and endovascular aneurysm repair (EVAR) are unclear, and hitherto artificial intelligence has not been used for this purpose. The aim was to compare the precision of survival estimates between the Kaplan-Meier (KM) method and the artificial intelligence derived method Neural Multi-Task Logistic Regression (N-MTLR), and to compare survival estimates as a function of patient age and time since surgery between OSR and EVAR using N-MTLR.

METHODS

All AAAs between 2003 and 2018 in Denmark were identified in the Danish vascular registry. Survival was estimated using the KM and N-MTLR methods, and prediction performance was estimated with the Brier score.

RESULTS

7 912 patients were included in the study, n = 6 569 (83%) men, median age 72 years (range 35 - 92), with a median follow-up time of 45.7 months (range 0 - 120). The two treatment cohorts, OSR n = 5 495 (69%), and EVAR n = 2 417 (31%), differed significantly in patient characteristics. The Brier score for KM increased from 0.044 to 0.244, and for N-MTLR from 0.044 to 0.206, from 90 days to 10 years. The N-MTLR method was more accurate than KM from 90 days to 10 years after surgery, p ≤ .025. N-MTLR demonstrated significant increased probability for survival for OSR in patients aged 58 - 76 years at five years, and 65 - 73 at 10 years after surgery, and the opposite was found for the benefit of EVAR in patients aged 72 - 85 years at one year, 85 - 90 years at five years, and for 85 - 90 year olds at 10 years after surgery.

CONCLUSION

N-MTLR outperforms KM for the entire post-operative follow-up time. This N-MTLR model has the potential to render more precise patient specific survival estimates and establish survival differences between subgroups of patients that KM is unable to detect, demonstrated here for different age groups.

Volumetric analysis of effectiveness of embolization for preventing type II endoleaks following endovascular aortic aneurysm repair

OBJECTIVE

The presence of endoleak was associated with the failure of endovascular aortic aneurysm repair (EVAR) treatment. The key to eliminating type II endoleak has shifted from reintervention to prevention. This study aimed to evaluate the effectiveness and safety of applying fibrin sealant to prevent type II endoleak in conjunction with EVAR.

METHODS

All patients with abdominal aortic aneurysm who underwent EVAR from June 2019 to July 2021 were reviewed. Patients were grouped as Group A: standard EVAR with preemptive embolization and Group B: standard EVAR alone. The primary endpoint was the incidence of type II endoleak. The secondary endpoints were aneurysm sac regression, the inferior mesenteric artery patency, the numbers of patent lumbar arteries, and all-cause mortality.

RESULTS

A total of 104 patients were included in Group A, and 116 were included in Group B. Technical success rate was 100%. The overall incidence of type II endoleak in Group A was significantly lower than that in Group B (4.8% vs 19.0%). The mean time of freedom from type II endoleak was 22.71 months for Group A (95% confidence interval, 21.59-23.83 months) and 19.89 months for Group B (95% confidence interval, 18.08-21.70 months). The Kaplan-Meier estimate of freedom from type II endoleak showed a significantly longer duration of freedom from type II endoleak in Group A (81.0% vs 95.2%). Group A showed a continuous sac regression tendency. In Group B, the sac volume decreased within 12 months but increased by 3.07 cm³ at 24 months. No complications were noted in both groups.

CONCLUSIONS

Nonselective preemptive embolization with porcine fibrin sealant during EVAR was safe and effective in preventing type II endoleak in the short and mid-term. Preemptive embolization can lead to a significantly higher sac regression rate. Larger patient populations and longer follow-ups with randomized control designed trials are expected to verify the long-term effectiveness and safety of preemptive embolization in preventing type II endoleak.

CXCR4 - a possible serum marker for risk stratification of abdominal aortic aneurysms

Background: Abdominal aortic aneurysm (AAA) rupture is still associated with a mortality rate of 80-90%. Imaging techniques or molecular fingerprinting for patient-specific risk stratification to identify pending rupture are still lacking. The chemokine (C-X-C motif) receptor (CXCR4) activation by CXCL12 ligand has been identified as a marker of inflammation and atherosclerosis, associated with AAA. Both are highly expressed in the aortic aneurysm wall. However, it is still unclear whether different expression levels of CXCR4 and CXCL12 can distinguish ruptured AAAs (rAAA) from intact AAAs (iAAA). Patients and methods: Abdominal aortic tissue samples (rAAA: n=29; iAAA: n=54) were excised during open aortic repair. Corresponding serum samples from these patients (n=9 from rAAAs; n=47 from iAAA) were drawn pre-surgery. Healthy aortic tissue samples (n=8) obtained from adult kidney donors during transplantation and serum samples from healthy adult volunteers were used as controls (n=5 each). Results: CXCR4 was mainly expressed in the media of the aneurysmatic tissue. Focal positive staining was also observed in areas of inflammatory infiltrates within the adventitia. In tissue lysates, no significant differences between iAAA, rAAA, and healthy controls were observed upon ELISA analysis. In serum samples, the level of CXCR4 was significantly increased in rAAA by 4-fold compared to healthy controls (p=0.011) and 3.0-fold for rAAA compared to iAAA (p<0.001). Furthermore a significant positive correlation between aortic diameter and serum CXCR4 concentration was found for both, iAAA and rAAA (p=0.042). Univariate logistic regression analysis showed that increased CXCR4 serum concentrations were associated with AAA rupture (OR: 4.28, 95% CI: 1.95-12.1, p=0.001). Conclusions: CXCR4 concentration was significantly increased in serum of rAAA patients and showed a significant correlation with an increased aortic diameter. The level of CXCR4 in serum was associated with a more than 4-fold risk increase for rAAA and thus could possibly serve as a biomarker in the future. However, further validation in larger studies is required.

The Impact of Completion and Follow-up Endoleaks on Survival, Reintervention, and Rupture

OBJECTIVE

Endoleaks may be seen at case completion of endovascular abdominal aortic aneurysm repair (EVAR), and the presence of an endoleak may impact outcomes. However, the clinical implications of various endoleaks seen during follow-up is not well-described. Therefore, we studied the impact of endoleaks at completion and at follow-up on mid-term outcomes.

METHODS

We reviewed patients who underwent EVAR from 2003 to 2016 within the VQI-Medicare database and identified patients with endoleak at procedure completion and during follow-up, excluding those presenting with rupture. We stratified cohorts by presence of completion and follow-up endoleak subtypes. The primary outcome was 5-year survival, and secondary outcomes included 5-year freedom-from-reintervention and freedom-from-rupture. We used Kaplan-Meier estimates and log-rank tests to analyze differences in time-to-event endpoints.

RESULTS

Of 21,745 patients with completion endoleak data, 5,085 (23%) had an endoleak. Compared to those without endoleak, those with type I endoleaks had lower five-year survival (69% vs. 75%, P<.001), type II endoleaks had higher survival (79%, P<.001), and types III, IV and indeterminate were not statistically different (73%, 73%, 75%, respectively). Freedom-from-reintervention for types I and III endoleaks were significantly lower than no endoleak cohort (I: 76%, P<.001; III: 72%, P<.001, vs. 83%), but freedom-from-rupture was higher for those with type II and III endoleak (95% and 97% vs. 94%, P<.001). Of 14,479 patients with detailed follow-up endoleak data, 2,290 (16%) had an endoleak. Compared to those without endoleak, types I and III had significantly lower 5-year survival (I: 80%, P=.002; III: 66%, P<.001 vs. 84%), but there were no differences for types II (82%) and indeterminate (77%). Those with any type of follow-up endoleak had lower 5-year freedom-from-reintervention (I: 70%, P<.001; II: 76%, P=.006; III: 36%, P<.001; indeterminate: 60%, P=.007 vs. 84%), and lower freedom-from-rupture (I: 92%, P<.001; II: 91%, P=.16; III: 88%, P=.01; indeterminate: 90%, P=.11 vs. 94%).

CONCLUSIONS

Compared to patients with no endoleak, those with type I completion endoleaks have lower 5-year survival and freedom-from-reintervention. Patients with types I and III follow-up endoleaks also have lower survival, and any endoleak at follow-up is associated with lower freedom-from-reintervention and freedom-from-rupture. These data highlight the importance of careful patient selection and close postoperative follow-up after EVAR, as the presence of endoleaks, specifically type I and III, over time portends worse outcomes.

Specific Overexpression of YAP in Vascular Smooth Muscle Attenuated Abdominal Aortic Aneurysm Formation by Activating Elastic Fiber Assembly via LTBP4

Abdominal aortic aneurysm (AAA) is a fatal vascular disease. Vascular smooth muscle cells (VSMCs) play a crucial role in the pathogenesis of AAA. Increasing evidence has shown that Yes-associated protein (YAP) is involved in diverse vascular diseases. However, the role of YAP in AAA remains unclear. The current study aimed to determine the role of YAP in AAA formation and the underlying mechanism. We found that YAP expression in VSMCs was markedly decreased in human and experimental AAA samples. Furthermore, VSMC-specific YAP overexpression prevented several pathogenic factor-induced AAA. Mechanistically, YAP overexpression in VSMCs promoted latent transforming growth factor-β binding protein 4 (LTBP4) expression, an important factor in elastic fiber assembly. Finally, silencing of LTBP4 in VSMCs abolished the protective role of YAP in AAA formation in vivo. Our results suggest that YAP promotes LTBP4-mediated elastic fibril assembly in VSMCs, which mitigates elastin degradation and AAA formation.

Abdominal aortic aneurysm growth rates in patients undergoing local ultrasound surveillance

Objectives

Abdominal aortic aneurysm ultrasound surveillance varies between hospitals in the United Kingdom. University Hospitals Bristol and Weston adopt a 6-monthly surveillance interval for 4.5-4.9 cm abdominal aortic aneurysm, which is a deviation from nationally recommended 3-monthly intervals. Assessment of abdominal aortic aneurysm growth rate, and the concurrent impact of abdominal aortic aneurysm risk factors and medications prescribed for risk factors, may inform whether this change in surveillance intervals is safe and appropriate.

Methods

This analysis was conducted retrospectively. A total of 1312 abdominal aortic aneurysm ultrasound scans from 315 patients between January 2015 and March 2020 were split into 0.5 cm groups, ranging from 3.0 to 5.5 cm. Abdominal aortic aneurysm growth rate was assessed with one-way analysis of variance. The impact of risk factors and risk factor medication on abdominal aortic aneurysm growth rate was analysed using multivariate and univariate linear regression and Kruskal-Wallis tests. Patient cause of death among surveillance patients was recorded.

Results

Abdominal aortic aneurysm growth rate was significantly associated with increased abdominal aortic aneurysm diameter (p < 0.001). There was a significant whole-group reduction in growth rate from 0.29 to 0.19 cm/year in diabetics compared to non-diabetics (p = 0.02), supported by univariate linear regression (p = 0.04). In addition, gliclazide patients had lower growth rate compared to patients not on the medication (p = 0.04). One abdominal aortic aneurysm rupture occurred <5.5 cm resulting in death.

Conclusion

Abdominal aortic aneurysm measuring 4.5-4.9 cm had a mean growth rate of 0.3 cm/year (± 0.18 cm/year). Therefore, mean growth rate and variability suggest patients are unlikely to surpass surgical threshold of 5.5 cm between the 6-monthly surveillance scans, supported by low rupture rates. This suggests the surveillance interval for 4.5-4.9 cm abdominal aortic aneurysm is a safe and appropriate deviation from national guidance. In addition, it may be pertinent to consider diabetic status when designing surveillance intervals.

Routine Inferior Mesenteric Artery Embolisation is Unnecessary Before Endovascular Aneurysm Repair

OBJECTIVE

A type II endoleak is the most common complication during surveillance after endovascular aneurysm repair (EVAR), and a patent inferior mesenteric artery (IMA) is a known risk factor for an endoleak. The effect of routine IMA embolisation prior to EVAR on overall outcome is unknown. The aim of the study was to compare two strategies: routine attempted IMA embolisation prior to EVAR (strategy in centre A) and leaving the IMA untouched (strategy in centre B).

METHODS

Patients were treated with EVAR in two centres during the period 2005 - 2015, and the data were reviewed retrospectively. The primary endpoints were re-intervention rate due to type II endoleaks and the late IMA embolisation rate. Secondary endpoints included EVAR related re-intervention, sac enlargement, aneurysm rupture, and open conversion rates.

RESULTS

Strategy A was used to treat 395 patients. The IMA was patent in 268 (67.8%) patients, and embolisation was performed in 164 (41.5%). The corresponding figures for strategy B were 337 patients with 279 (82.8%) patent IMAs, two (0.6%) of which were embolised. The mean duration of follow up was 70 months for strategy A and 68.2 months for strategy B. The re-intervention rates due to a type II endoleak were 12.9% and 10.4%, respectively (p = .29), with no significant difference in the rate of re-interventions to occlude a patent IMA (2.0% and 4.7%, respectively; p = .039). The EVAR related re-intervention rate was similar, regardless of strategy (24.1% and 24.6%, respectively; p = .93). Significant sac enlargement was seen in 20.3% of cases treated with strategy A and in 19.6% treated with strategy B (p = .82). The rupture and conversion rates were 2.5% and 2.1% (p = .69) and 1.0% and 1.5% (p = .40), respectively.

CONCLUSION

The strategy of routinely embolising the IMA does not seem to yield any significant clinical benefit and should therefore be abandoned.

Open Surgery for Abdominal Aortic Aneurysm: 980 Consecutive Patient Outcomes from a High-Volume Centre in the United Kingdom

BACKGROUND

Controversy persists regarding the optimal treatment for large abdominal aortic aneurysm (AAA), highlighted by the publication of the National Institute for Health and Care Excellence (NICE) guideline (NG156) on March 2020. The pendulum of opinion swings once more from endovascular to open surgical treatment. We report our experience over the last 15 years in treating consecutive AAA by open surgery.

METHODS

A retrospective review of a prospectively collected vascular database of all patients undergoing infra-renal open abdominal aortic aneurysm repair (OR) repair from 2004 to 2019 at the largest aneurysm centre in the United Kingdom. OR for elective and emergency (ruptured and symptomatic) outcomes included early morbidity and 30-day mortality, and long-term survival.

RESULTS

1017 patients underwent OR between 2004-2019, on application of our inclusion-criteria 994 patients formed our cohort for analysis (81.2% male) with a mean age 73.6 ± 7.8 years treated by OR for AAA. In that group 672 were elective and 308 were emergency (for ruptured or symptomatic). Overall 30 day mortality was 11.3%, elective 30 day mortality was 2.5%, and emergency 30 day mortality was 29.9%. 30 day re-intervention rate was 9.5%, (elective 7.0%, emergency 15.9%). Survival at 1000 days for elective repair was 72 v 46.7% for emergency and at 2000 days was 43.4% for elective v 25% for emergency.

CONCLUSION

Our data confirm that open surgery for AAA can be performed in large volume centres quite safely. Elective and Emergency surgery does affect early 30 day mortality but does not influence long-term outcome.

Suture-mediated closure devices for percutaneous endovascular abdominal aneurysm repair

Purpose

Endovascular procedures such as endovascular aneurysm repair or transcatheter aortic valve implantation have become very common because of reduced patient traumatisation and the ability to use shorter or local anaesthesia. In these procedures large-bore sheath devices are used. Access with percutaneous closure is an alternative method to surgical cutdown in groins. The aim of the study was to assess the correlation between sheath size and unsuccessful haemostasis. In addition, the effectiveness of haemostasis after a percutaneous procedure and the number and type of complications were evaluated.

Material and methods

There were 202 patients included in the study. Patients with abdominal aortic aneurysm were qualified to percutaneous aortic stentgraft implantation with Perclose Proglide preclosure technique.

Results

There were 384 access sites performed with 12F to 22F sheaths during aortic stentgraft implantation with Perclose Proglide (Abbott Vascular, Santa Clara, CA, USA) preclosure technique. High effectiveness of haemostasis (98%), low percentage of short- and mid-term complications (2.6%), and infinitesimal number of surgical conversions (n = 5) were stated in the study. There was no correlation between diameter of used introducer sheath and lack of haemostasis observed (Fisher-Freeman-Halton test; p = 0.122). No relationship between diameter of introducer sheath and number of closure devices was observed (c² = 2.436; df = 5; p = 0.786).

Conclusions

Large-bore device percutaneous procedures with closure devices are effective and safe. High effectiveness of haemostasis (98%) was observed in the study group, with a low percentage of complications (2.6%). There was no correlation between size of the vascular access and the lack of haemostasis found in the study.

Quantitative (1)H Nuclear Magnetic Resonance (qNMR) of Aromatic Amino Acids for Protein Quantification

Hydrolysis of protein samples into amino acids facilitates the use of NMR spectroscopy for protein and peptide quantification. Different conditions have been tested for quantifying aromatic amino acids and proteins. The pH-dependent signal shifts in the aromatic region of amino acid samples were examined. A pH of 12 was found to minimize signal overlap of the four aromatic amino acids. Several aromatic compounds, such as terephthalic acid, sulfoisophthalic acid, and benzene tricarboxylic acid, were applied as internal standards. The quantification of amino acids from an amino acid standard was performed. Using the first two suggested internal standards, recovery was ~97% for histidine, phenylalanine, and tyrosine at a concentration of approximately 1 mM in solution. Acidic hydrolysis of a certified reference material (CRM) of bovine serum albumin (BSA) and subsequent quantification of Phe and Tyr yielded recoveries of 98% ± 2% and 88% ± 4%, respectively, at a protein concentration of 16 g/L or 250 µM.

Atypical patterns of spinal segment degeneration in patients with abdominal aortic aneurysms

PURPOSE

Abdominal aortic aneurysms (AAAs) affect the vascular perfusion of the lumbar spine. The treatment of AAAs with endovascular aortic aneurysm repair (EVAR) completely occludes the direct vascular supply to the lumbar spine. We hypothesized that patients with AAA who undergo EVAR show a different pattern of spinal degeneration than individuals without AAA.

METHODS

In this retrospective institutional review board-approved study, 100 randomly selected patients with AAA who underwent EVAR with computed tomography (CT) scans between 2005 and 2017 were compared with age- and gender-matched controls without AAA. In addition, long-term follow-up CT images (> 6 months before EVAR, at the time of EVAR, and > 12 months after EVAR) of the patients were analysed to compare the progression of degeneration from before to after EVAR. Degeneration scores, lumbar levels with the most severe degeneration, and lumbar levels with progressive degeneration were analysed in all CT images. Fisher's exact test, Wilcoxon signed-rank test, and Mann-Whitney U test were performed for statistical analyses.

RESULTS

Compared with the control group (n = 94), the most severe degeneration was more commonly detected in the mid-lumbar area in the patient group (n = 100, p = 0.016), with significantly more endplate erosions being detected in the lumbar spine (p = 0.015). However, EVAR did not result in significant additional acceleration of the degenerative process in the long-term follow-up analysis (n = 51).

CONCLUSION

AAA is associated with atypical, more cranially located spinal degradation, particularly in the mid-lumbar segments; however, EVAR does not seem to additionally accelerate the degenerative process. This observation underlines the importance of disc and endplate vascularization in the pathomechanism of spinal degeneration.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

IL-1 in Abdominal Aortic Aneurysms

Abdominal Aortic Aneurysms (AAA) remain a clinically devastating disease with no effective medical treatment therapy. AAAs are characterized by immune cell infiltration, smooth muscle cell apoptosis, and extracellular matrix degradation. Interleukin-1 (IL-1) has been shown to play role in AAA associated inflammation through immune cell recruitment and activation, endothelial dysfunction, production of reactive oxygen species (ROS), and regulation of transcription factors of additional inflammatory mediators. In this review, we will discuss the principles of IL-1 signaling, its role in AAA specific inflammation, and regulators of IL-1 signaling. Additionally, we will discuss the influence of genetic and pharmacological inhibitors of IL-1 on experimental AAAs. Evidence suggests that IL-1 may prove to be a potential therapeutic target in the management of AAA disease.

One-year sac regression is associated with freedom from fatal adverse events after endovascular aneurysm repair

OBJECTIVE

Although the predictors of long-term prognosis after endovascular aneurysm repair (EVAR) have been investigated, several reports have suggested that early sac shrinkage (ESS) is associated with superior long-term prognosis. However, it was not clear whether ESS was associated with aneurysm-related mortality. The aim of this study was to define fatal adverse events and to examine their association with ESS.

METHODS

All consecutive patients who underwent EVAR for an abdominal aortic aneurysm at Nagoya University Hospital between June 2007 and August 2018 were identified. We defined ESS as an aneurysm diameter decrease of 10 mm or more at 1 year after EVAR, and we defined fatal adverse events as aneurysm-related death, aneurysm sac rupture, open conversion, secondary type Ia endoleak, or secondary type IIIa/b endoleak. Then, we evaluated the association between ESS and fatal adverse events and identified predictors of ESS.

RESULTS

During the study period, 553 patients were identified and included. Fatal adverse events occurred in 42 patients (7.6%), and the details of the fatal adverse events were as follows: 13 aneurysm-related deaths, 17 aneurysm sac ruptures, 14 open conversions, 13 type Ia endoleaks, and 6 type III endoleaks. ESS occurred in 146 patients (26.4%). Kaplan-Meier curves showed that the ESS group had a significantly lower incidence of fatal adverse events (P < .001). Multivariate analysis showed that there were significant differences in terms of 5 or more preoperatively patent lumbar arteries (odds ratio [OR], 0.67; P = .049; 95% confidence interval [CI], 0.45-1.00), chronic kidney disease (OR, 0.49; P < .01; 95% CI, 0.29-0.84), and Zenith endograft use (OR, 1.76; P < .01; 95% CI, 1.16-2.67). Furthermore, the percentage of cases that achieved an aneurysm diameter of less than 40 mm was significantly higher in the ESS group (76.0% vs 15.5%; P < .01). The use of Zenith endografts showed a significantly higher rate of aneurysm disappearance than the use of Endurant endografts (P < .01) and Excluder endografts (P < .01). In addition, it was found that ESS was more likely to occur with the use of Zenith endografts, even when propensity score matching was performed for the neck morphology.

CONCLUSIONS

ESS was associated with a lower rate of life-threatening adverse events after EVAR. The use of Zenith endografts was a predictor of ESS and was associated with increased rates of long-term sac shrinkage and aneurysm disappearance compared with the Endurant and Excluder endografts. Using the predictors of ESS identified in this study, we may be able to expand the indications for EVAR to patients with a longer life expectancy.

Circulating Extracellular Vesicles: Their Role in Patients with Abdominal Aortic Aneurysm (AAA) Undergoing EndoVascular Aortic Repair (EVAR)

Abdominal aortic aneurysm (AAA) is a frequent aortic disease. If the diameter of the aorta is larger than 5 cm, an open surgical repair (OSR) or an endovascular aortic repair (EVAR) are recommended. To prevent possible complications (i.e., endoleaks), EVAR-treated patients need to be monitored for 5 years following the intervention, using computed tomography angiography (CTA). However, this radiological method involves high radiation exposure in terms of CTA/year. In such a context, the study of peripheral-blood-circulating extracellular vesicles (pbcEVs) has great potential to identify biomarkers for EVAR complications. We analyzed several phenotypes of pbcEVs using polychromatic flow cytometry in 22 patients with AAA eligible for EVAR. From each enrolled patient, peripheral blood samples were collected at AAA diagnosis, and after 1, 6, and 12 months following EVAR implantation, i.e. during the diagnostic follow-up protocol. Patients developing an endoleak displayed a significant decrease in activated-platelet-derived EVs between the baseline condition and 6 months after EVAR intervention. Furthermore, we also observed, that 1 month after EVAR implantation, patients developing an endoleak showed higher concentrations of activated-endothelial-derived EVs than patients who did not develop one, suggesting their great potential as a noninvasive and specific biomarker for early identification of EVAR complications.

Evaluating feasibility of using national registries for identification, invitation, and ultrasound examination of persons with hereditary risk for aneurysm disease-detecting abdominal aortic aneurysms in first degree relatives (adult offspring) to AAA patients (DAAAD)

BACKGROUND

Sweden and the UK invite all 65-year-old men to a population-based ultrasound-based screening program to detect abdominal aortic aneurysms (AAA). First-degree relatives of patients with AAA are reported to have an increased risk to develop AAA, both women and men, but are not invited to screening. The "Detecting AAA in First Degree Relatives to AAA patients" (DAAAD) was designed to detect the true prevalence in adult offspring to AAA patients and to evaluate if national registries could be used for identification of index persons and their adult children with a high risk for the disease. The aim of this study is to summarize the design and methodology for this registry-based study.

METHODS

The study is based on a registry-based extraction and identification of a risk group in the population with a subsequent identification of their adult offspring. The targeted risk group suffers a heredity for a potentially lethal disease, AAA (n = 750) and matched control group without heredity for AAA is also identified and invited (n = 750). The participation rate in the population-based AAA screening program for men is 75% regionally. This population is younger and have a lower prevalence. A participation rate of 65% is considered clinically adequate. For the DAAAD study, a stratified analysis of the primary outcome, prevalence, will be performed for women and men separately. Two other planned projects are based on the material: firstly, evaluation of the anxiety for disease and health-related quality of life (HRQoL) and, secondly, the cost-effectiveness of the study.

DISCUSSION

In conclusion, this feasibility study will be instrumental in supporting the development of a possible new model to invite persons with high risk to develop hereditary rare diseases. To our knowledge, this is a unique, safe, and most likely to be a cost-efficient model to invite targeted risk groups for selected screening. If the study design and the results are shown to be cost-effective at the detected participation rate and prevalence, it should be further evaluated and adopted to a national screening program. The model also invites both women and men, which is unique for this specific patient group, considering that all population-based screening programs only include men.

TRIAL REGISTRATION

This trial is registered at the website of Clinical Trials.

CLINICALTRIALS

gov identifier, NCT4623268.

Computed Tomography Angiography Markers and Intraluminal Thrombus Morphology as Predictors of Abdominal Aortic Aneurysm Rupture

Background: Abdominal aortic aneurysm (AAA) is a complex vascular disease characterized by progressive and irreversible local dilatation of the aortic wall. Currently, the indication for repair is linked to the transverse diameter of the abdominal aorta, using computed tomography angiography imagery, which is one of the most used markers for aneurysmal growth. This study aims to verify the predictive role of imaging markers and underlying risk factors in AAA rupture. Methods: The present study was designed as an observational, analytical, retrospective cohort study and included 220 patients over 18 years of age with a diagnosis of AAA, confirmed by computed tomography angiography (CTA), admitted to Vascular Surgery Clinic of Mures County Emergency Hospital in Targu Mures, Romania, between January 2018 and September 2022. Results: Patients with a ruptured AAA had higher incidences of AH (p = 0.006), IHD (p = 0.001), AF (p < 0.0001), and MI (p < 0.0001), and higher incidences of all risk factors (tobacco (p = 0.001), obesity (p = 0.02), and dyslipidemia (p < 0.0001)). Multivariate analysis showed that a high baseline value of all imaging ratios markers was a strong independent predictor of AAA rupture (for all p < 0.0001). Moreover, a higher baseline value of DAmax (OR:3.91; p = 0.001), SAmax (OR:7.21; p < 0.001), and SLumenmax (OR:34.61; p < 0.001), as well as lower baseline values of DArenal (OR:7.09; p < 0.001), DACT (OR:12.71; p < 0.001), DAfemoral (OR:2.56; p = 0.005), SArenal (OR:4.56; p < 0.001), SACT (OR:3.81; p < 0.001), and SThrombusmax (OR:5.27; p < 0.001) were independent predictors of AAA rupture. In addition, AH (OR:3.33; p = 0.02), MI (OR:3.06; p = 0.002), and PAD (OR:2.71; p = 0.004) were all independent predictors of AAA rupture. In contrast, higher baseline values of SAmax/Lumenmax (OR:0.13; p < 0.001) and ezetimibe (OR:0.45; p = 0.03) were protective factors against AAA rupture. Conclusions: According to our findings, a higher baseline value of all imaging markers ratios at CTA strongly predicts AAA rupture and AH, MI, and PAD highly predicted the risk of rupture in AAA patients. Furthermore, the diameter of the abdominal aorta at different levels has better accuracy and a higher predictive role of rupture than the maximal diameter of AAA.

Towards Precritical Medical Therapy of the Abdominal Aortic Aneurysm

Pharmacotherapy for abdominal aortic aneurysm (AAA) can be useful for prevention, especially in people at higher risk, for slowing down AAA progression, as well as for post-surgery adjuvant treatment. Our review focuses on novel pharmacotherapy approaches targeted towards slowing down progression of AAA, known also as secondary prevention therapy. Guidelines for AAA are not specific to slow down the expansion rate of an abdominal aortic aneurysm, and therefore no medical therapy is recommended. New ideas are urgently needed to develop a novel medical therapy. We are hopeful that in the future, pharmacologic treatment will play a key role in the prevention and treatment of AAA.