Prevalence and trends of the abdominal aortic aneurysms epidemic in general population--a meta-analysis

How to improve epidemiological trustworthiness concerning abdominal aortic aneurysms

BackgroundResearch on degenerative abdominal aortic aneurysms (AAA) is hampered by complex pathophysiology, sub-optimal pre-clinical models, and lack of effective medical therapies. In addition, trustworthiness of existing epidemiological data is impaired by elements of ambiguity, inaccuracy, and inconsistency. Our aim is to foster debate concerning the trustworthiness of AAA epidemiological data and to discuss potential solutions.MethodsWe searched the literature from the last five decades for relevant epidemiological data concerning AAA development, rupture, and repair. We then discussed the main issues burdening existing AAA epidemiological figures and proposed suggestions potentially beneficial to AAA diagnosis, prognostication, and management.ResultsRecent data suggest a heterogeneous scenario concerning AAA epidemiology with rates markedly varying by country and study cohorts. Overall, AAA prevalence seems to be decreasing worldwide while mortality is apparently increasing regardless of recent improvements in aortic-repair techniques. Prevalence and mortality are decreasing in high-income countries, whereas low-income countries show an increase in both. However, several pieces of information are missing or outdated, thus systematic renewal is necessary. Current AAA definition and surgical criteria do not consider inter-individual variability of baseline aortic size, further decreasing their reliability.ConclusionsSwitching from flat aortic-size thresholds to relative aortic indices would improve epidemiological trustworthiness regarding AAAs. Aortometry standardization focusing on simplicity, univocity, and accuracy is crucial. A patient-tailored approach integrating clinical data, multi-adjusted indices, and imaging parameters is desirable. Several novel imaging modalities boast promising profiles for investigating the aortic wall. New contrast agents, computational analyses, and artificial intelligence-powered software could provide further improvements.

Prior abdominal surgery is not associated with 30-day mortality or morbidities after endovascular repair of complex abdominal aortic aneurysm

BackgroundPrior abdominal surgery (PAS) has the potential to affect outcomes of abdominal aortic aneurysm (AAA) repair. Recently, endovascular aneurysm repair (EVAR) has been expanded among patients with complex AAA, which involves visceral branches in the upper abdominal aortic. However, outcomes of EVAR for complex AAA in patients with PAS have not been examined. This study aimed to investigate the impact of PAS on 30-day outcomes in EVAR for complex AAA.MethodsPatients who underwent EVAR for complex AAA were identified in ACS-NSQIP targeted database from 2012 to 2022. Complex AAA was defined as juxtarenal, suprarenal, or pararenal proximal extent, Type IV thoracoabdominal aneurysm, or aneurysms treated with Zenith Fenestrated endograft. Patients with age less than 18 years, ruptured AAA with or without hypotension, acute intraoperative conversion to open, and emergency presentation were excluded. Multivariable logistic regression was used to compare 30-day postoperative outcomes of patients with and without PAS. Demographics, baseline characteristics, aneurysm diameter, indication for surgery, proximal and distant aneurysm extent, anesthesia, and concomitant procedures were adjusted.ResultsThere were 515 (28.34%) and 1302 (71.66%) patients with and without PAS, respectively, who underwent EVAR for complex AAA. Patients with and without PAS had comparable 30-day mortality (3.11% vs 3.00%, aOR = 0.766, 95 CI = 0.407-1.442, p = .41). Organ system complications including cardiac complications, stroke, pulmonary complications, and renal complications were comparable between patients with and without PAS. All other 30-day outcomes were similar between groups. However, patients with PAS had higher 30-day readmission rate (11.65% vs 7.14%, aOR = 1.634, 95 CI = 1.145-2.331, p = .01).ConclusionWhile PAS has high prevalence among patients undergoing EVAR for complex AAA, it does not impact 30-day mortality and morbidities. Thus, EVAR for complex AAA can be considered safe for patients with PAS in terms of short-term outcomes, despite the long-term prognosis in these patients being needed in further studies.

Anesthesia choice for endovascular repair of complex abdominal aortic aneurysm: A propensity-score-matched study from the ACS-NSQIP database from 2012 to 2022

BackgroundWhile general anesthesia has been the dominant anesthesia used in endovascular aneurysm repair (EVAR), locoregional anesthesia is suggested as a viable alternative for eligible patients. However, the majority of previous findings came from infrarenal EVAR while the choice of anesthesia for complex EVAR remains less established. This study aimed to retrospectively compare the 30-day outcomes of patients who underwent non-emergency complex EVAR under locoregional or general anesthesia.MethodsPatients who had EVAR for complex abdominal aortic aneurysm (AAA) were selected from ACS-NSQIP targeted database between 2012 and 2022. Complex AAA included juxtarenal, suprarenal, or pararenal proximal extent, Type IV thoracoabdominal aneurysm, and/or aneurysms treated with Zenith Fenestrated endograft. Exclusion criteria included age under 18 years, ruptured AAA, acute intraoperative conversion to open, and emergency. A 1:2 propensity-score matching was used to balance demographics, baseline characteristics, aneurysm diameter, distant aneurysm extent, and concomitant procedures between the locoregional and general anesthesia groups. Thirty-day outcomes were examined.ResultsThere were 284 (9.63%) and 2664 (90.37%) patients who underwent EVAR for complex AAA under locoregional and general anesthesia, respectively. All patients under locoregional anesthesia were matched to 549 patients under general anesthesia. Patients under locoregional and general anesthesia had comparable risks of mortality and surgical complications. However, patients under locoregional anesthesia had a shorter hospital length of stay (LOS; 2.37 ± 3.25 vs 3.35 ± 4.81 days, p < .01).ConclusionBoth locoregional and general anesthesia are effective options for eligible patients undergoing complex EVAR. However, patients under general anesthesia had a longer hospital LOS by about 1 day, which was likely due to increased case complexity that may necessitate prolonged recovery and closer monitoring for complications. To further optimize anesthesia protocols for these procedures, future prospective studies may be necessary.

Echocardiographic analysis of abdominal aorta dimensions and their associations with demographic characteristics in a healthy population

INTRODUCTION

Determining the normal diameter of the abdominal aorta in different populations and its relationship with other demographic factors is crucial for diagnosing and managing abdominal aortic diseases. This study aimed to assess the size of the abdominal aorta in a healthy Iranian population.

METHODS

This cross-sectional study included healthy individuals. Various variables including age, sex, height, and weight were measured as part of this study. We performed an echocardiographic evaluation to assess the aortic sections.

RESULTS

The study encompassed 167 participants, predominantly women (67.7%). Notable differences in sizes of the ascending aorta, aortic arch, sinus of Valsalva, and abdominal aorta were observed across the four age groups. Men exhibited greater sizes in multiple aortic sections within the 45-64 age group. Correlation and regression analyses demonstrated significant positive relationships between abdominal aorta size and various aortic dimensions, with a one-millimeter increase in ascending or descending aorta diameter corresponding to a 0.23 and 0.35 mm increase, respectively, in abdominal aorta diameter. The relationship between abdominal aorta size and demographic factors such as gender, age, weight, BSA, and SBP was explored, revealing age as a significant predictor.

CONCLUSIONS

We observed significant differences in the sizes of distinct aortic sections across different age groups, underscoring the importance of considering age-related changes when evaluating aortic characteristics. These findings contribute to our understanding of the structural changes that occur in the aorta over time. Echocardiographic screening of the abdominal aorta would enable echocardiologists to diagnose the aneurysmal aorta.

Local Versus General Anesthesia in Emergency Endovascular Repair of Infrarenal Abdominal Aortic Aneurysm

BACKGROUND

While general anesthesia (GA) has been the common choice of anesthesia for patients undergoing endovascular aneurysm repair (EVAR), local anesthesia (LA) has been proposed as an effective alternative for eligible patients. However, the choice of anesthesia in emergency EVAR situations remains less explored. Therefore, this study aimed to perform a retrospective analysis to compare the 30-day outcomes of patients who underwent emergency infrarenal EVAR receiving either LA or GA.

METHODS

Patients who underwent emergency infrarenal EVAR were identified in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) targeted database from 2012 to 2022. Exclusion criteria included age less than 18 years, acute intraoperative conversion to open surgery, and intraoperative anesthesia conversion. The 1:1 propensity-score matching and multivariable logistic regression were separately used to balance preoperative factors between patients who received LA and GA. Thirty-day postoperative outcomes were examined.

RESULTS

There were 258 (14.58%) and 1512 (85.42%) patients who underwent emergency EVAR under LA and GA, respectively. After multivariable analysis, patients who were under LA had lower mortality (11.24% vs 13.96%, aOR=0.61, 95% confidence interval [CI]=0.395-0.944, p=0.03), pulmonary complications (10.85% vs 17.59%, aOR=0.495, 95% CI=0.322-0.76, p<0.01), renal complications (5.04% vs 7.47%, aOR=0.545, 95% CI=0.303-0.983, p=0.04), wound complications (0.39% vs 3.64%, aOR=0.089, 95% CI=0.012-0.649, p=0.02), and 30-day readmission (6.59% vs 11.24%, aOR=0.564, 95% CI=0.334-0.953, p=0.03). Moreover, patients under LA had shorter operative time (p<0.01) and shorter length of stay (p=0.02).

CONCLUSION

The LA is associated with better 30-day outcomes in emergency infrarenal EVAR. Therefore, in emergency EVAR, it may be advisable to consider LA over GA for eligible patients. Prospective studies in the future can be warranted to further support this anesthesia practice.

CLINICAL IMPACT

The choice of anesthesia in emergency endovascular aneurysm repair (EVAR) remains unexplored. This study performed a retrospective analysis to compare the 30-day outcomes of patients who underwent emergency infrarenal EVAR receiving local anesthesia (LA) or general anesthesia (GA). After propensity-score matching/multivariable analysis to balance preoperative differences, patients under LA were found to have lower 30-day mortality, pulmonary, renal, and wound complications, 30-day readmission, shorter operative time, and shorter hospital stay. In emergency EVAR, it may be advisable to consider LA over GA for eligible patients. Prospective studies in the future can be warranted to further support this anesthesia practice.

Identifying abdominal aortic aneurysm size and presence using Natural Language Processing of radiology reports: a systematic review and meta-analysis

BACKGROUND AND AIM

Prior investigations of the natural history of abdominal aortic aneurysms (AAAs) have been constrained by small sample sizes or uneven assessments of aggregated data. Natural language processing (NLP) can significantly enhance the investigation and treatment of patients with AAAs by swiftly and effectively collecting imaging data from health records. This meta-analysis aimed to evaluate the efficacy of NLP techniques in reliably identifying the existence or absence of AAAs and measuring the maximal abdominal aortic diameter in extensive datasets of radiology study reports.

METHOD

The PubMed, Scopus, Web of Science, Embase, and Science Direct databases were searched until March 2024 to obtain pertinent papers. The RAYYAN intelligent tool for systematic reviews was utilized to screen the studies. The meta-analysis was conducted using STATA v18 software. Egger's test was employed to evaluate publication bias. The Newcastle Ottawa Scale was employed to assess the quality of the listed studies. A plot digitizer was employed to extract digital data.

RESULT

A total of 39,094 individuals with AAA were included in this analysis. Twenty-seven thousand three hundred twenty-six patients were male, and 11,383 were female. The mean age of the total participants was 73.1 ± 1.25 years. Analysis results for pooled estimation of performance variables such as: The sensitivity, specificity, precision, and accuracy of the implemented NLP model were analyzed as follows: 0.89(0.88-0.91), 0.88 (0.87-0.89), 0.92 (0.89-0.95), and 0.91 (0.89-0.93) respectively. The aneurysm diameter size difference reported in follow-up before and after NLP implementation in the included studies showed a 0.05 cm reduction in size, which was statistically significant.

CONCLUSION

NLP holds great potential for automating the detection of AAA size and presence in radiology reports, enhancing efficiency and scalability over manual review. However, challenges persist. Variability in report formats, terminology, and unstructured data can compromise accuracy. Additionally, NLP models rely on high-quality, annotated training datasets, which may be incomplete or unrepresentative. While NLP aids in identifying AAA-related data, human oversight is essential to ensure decisions are informed by the patient's broader clinical context. Ongoing algorithm refinement and seamless integration into clinical workflows are key to improving NLP's utility and reliability in this field.

Endovascular Solutions for Abdominal Aortic Aneurysms: Fenestrated, Branched and Custom-Made Devices

BACKGROUND

Abdominal aortic aneurysm (AAA) has a prevalence of 4.8%. AAA rupture is associated with significant mortality, thus surgical intervention is generally required once the aneurysm diameter exceeds 5.5 cm. Endovascular aneurysm repair (EVAR) is the predominant repair modality for AAA. However, in patients with complex aortic anatomy, fenestrated or branched EVAR is a superior repair option vs standard EVAR. Fenestrated and branched endoprostheses can be off-the-shelf or custom-made, which offers a more individualised approach.

AIM

To summarise and evaluate the clinical outcomes achieved by fenestrated EVAR (FEVAR) and branched EVAR (BEVAR), and to explore the role of custom-made endoprostheses in contemporary AAA management.

METHODS

A literature search using Ovid Medline and Google Scholar was conducted to identify literature pertaining to the use and outcomes of fenestrated, branched, fenestrated-branched and custom-made endoprostheses for AAA repair.

RESULTS

FEVAR is an effective repair modality for patients with AAA that offers similar early survival, improved early morbidity but higher rates of reintervention in comparison to open surgical repair (OSR). Compared with standard EVAR, FEVAR is associated with similar in-hospital mortality yet higher rates of morbidity, especially regarding renal outcomes. BEVAR outcomes are rarely reported exclusively in the context of AAA repair. When reported, BEVAR is an acceptable alternative to EVAR in the treatment of complex aortic aneurysms and has similar reported complication issues to FEVAR. Custom-made grafts are a good alternative treatment option for complex aneurysms where hostile aneurysm anatomy precludes the use of conventional EVAR and sufficient time is available for the manufacturing of such devices.

CONCLUSION

FEVAR offers a very effective treatment for patients with complex aortic anatomy and has been well-characterised over the past decade. RCTs and longer-term studies are desirable for unbiased comparison of non-standard EVAR modalities.

Characteristics and Ethnic Distribution of Aortic Aneurysms in a Caribbean Cohort

BACKGROUND

 There is a paucity of data regarding relationships between patient demographics and aneurysm characteristics in the West Indies. With this in mind, a retrospective cross-sectional review was conducted analyzing the computed tomography aortogram reports/images of 273 aortic aneurysms.

METHODS

 Data were collected and analyzed on ethnicity, size, type, morphology, presence and maximum size of thrombus and aneurysm location, demographics, and clinical presentation with correlations.

RESULTS

 There were 273 patients with aortic aneurysms giving an incidence rate of 4.33 per 100,000 people per annum. Statistically significant associations were noted with age, gender, and ethnicity. All false aneurysms were male (p = 0.004). The average size of aortic aneurysms being 0.7 cm larger in males than females (p < 0.001). Females were more likely to present with rupture (p = 0.001). Thrombus was more likely in males, Black and mixed races, and in the 8th decade (p < 0.001). Mean age of presentation was the highest in East Indians at 78 than the other ethnicities (Chinese: 65, Black: 70, mixed: 71, White: 73).

CONCLUSION

 Aortic aneurysmal disease is increasing in Trinidad and the Caribbean. Infrarenal fusiform aneurysms are the most common types with many significant differences based on age, gender, and ethnicity in the Caribbean population.

Evaluation of Aneurysm Cases Undergoing Surgery at a Tertiary Center in Iran: A 22-year Retrospective Study

Background and Aims

An arterial aneurysm is characterized by a localized expansion of a blood vessel relative to its original dimensions. Specifically, an abdominal aortic aneurysm (AAA) is identified as an aortic diameter measuring at least one and a half times the standard diameter at the renal artery level, approximately equivalent to 2.0 cm. In this study, we aim to evaluate the prevalence of AAA, along with the clinical features, trend, and incidence of ruptured AAA among patients undergoing surgery in our center.

Methods

The database of patients operated in Namazi Hospital from 2000 to 2021 was retrieved and patients undergoing vascular surgeries due to aneurysm were reviewed. All data were analyzed with SPSS version 26.0.

Results

A total of 599 cases of aneurysm were operated, among which 334 were contributed to the aorta and included in our study. The average age of the participants was 69.6 (SD: 12.1, range 16-93) years and 161 (85.2%) were male. The majority of cases were in the 60 to 80 years age group (n = 205; 62.5%). There was a significant association between the age groups and the AAA rupture (p = 0.003), with the highest occurrence among the above 80 years age group (n = 37, 49.3%). Regarding the location of the aneurysm, 274 were located in the infrarenal and abdominal region, 21 in the thoracoabdominal region, and 12 in the thoracic region. Among the cases in our study, 112 were cases of ruptured aneurysms. Furthermore, the age of patients with ruptured aneurysm were significantly higher compared to non-ruptured patients (71.8 vs. 68.5; p = 0.019).

Conclusion

We observed an increase in the incidence of AAA surgeries in our center throughout the years, with the population growing towards younger population, while the incidence of rupture increasing towards older age groups.

Distal Landing Zone-Related Complications of Conventional Endovascular Aneurysm Repair (EVAR) in the Long Term: A Comprehensive Systematic Review

The aim of this systematic review is to evaluate the late-onset complications considering the distal landing zones (DLZ) in patients with abdominal aortic aneurysm (AAA) treated by conventional endovascular aneurysm repair (EVAR). We conducted a systematic review of electronic databases, clinical trial registries, and grey literature to retrieve studies on this issue. The inclusion criteria could be summarized as follows: (1) observational studies or case series with more than 30 patients included, (2) at least three-year follow-up, and (3) endpoints including endoleak type Ib (ELIB) or cranial iliac limb migration/retraction (CLR) or DLZ failure-related reinterventions or other complications. Of the 517 potentially eligible studies, the detailed search revealed eight articles with a total of 2569 patients for further investigation. Due to the extreme heterogeneity in definitions and reporting outcomes among the included studies, the synthesis and meta-analysis of data were not plausible. A quantitative assessment of reported outcomes revealed a pooled incidence of 2.1% for ELIB, 1.7% for CLR, and 5.7% for DLZ failure-related reinterventions. Data were considered controversial to extract a consensus for the dilatation of the DLZ. This systematic review delineates the importance of late-onset complications originating from DLZ failures for the longevity of an EVAR procedure and gathers the current knowledge regarding the magnitude and clinical implications of DLZ failure from the existing literature and in the best available quality. Current literature data show a blurred image regarding the long-term morphological alterations of iliac arteries and especially in the impact of DLZ dilatation and emphasize the necessity of prolonged follow-up for at least five years.

Recurrent peripheral ischemia following endovascular repair of an infrarenal aortic aneurysm: what did we miss?

We document a case of a 75-year-old patient with a history of hypercholesterolemia and hypertension, who underwent endovascular aortic repair (EVAR) for an infrarenal abdominal aortic aneurysm (AAA) with common iliac artery ectasia. Despite an initially successful procedure, the patient experienced recurrent episodes of acute limb ischemia in his right leg. Subsequent imaging revealed thrombus formation distal to the stent graft, constituting a potential source of embolization, which warranted a reevaluation of the treatment strategy. This case highlights some of the complexities associated with managing AAA patients. In the context of EVAR, it emphasizes the significance of careful patient selection, meticulous endograft implantation, and watchful follow-up while tailoring treatment according to individual patient needs and anatomical considerations.

The Long-Term Progression of Aneurysmal Disease in Common Iliac Arteries After Standard EVAR and Its Clinical Implications

Introduction: The progression of aneurysmal disease in the common iliac arteries (CIAs) after EVAR remains an insufficiently investigated field. The purpose of this study is to investigate the long-term outcomes of standard elective EVAR with a variety of last-generation bifurcated aortic endografts in relation with the progression of aneurysmal disease in the CIAs. Methods: This is a prospective cohort study of 168 patients, who were treated with six different endografts between 2013 and 2018 and completed the 5-year computed tomography aortoangiography (CTA) follow-up. Postoperative CTA analysis included CIA measurements at four diameters' points and two length levels in three postoperative time spots: first, 24th, and 60th months. All EVAR-related adverse events were recorded, including migrations, endoleaks, limb occlusions, reinterventions, ruptures, and mortality. Results: At both time intervals, a significant and nearly linear dilatation and elongation of CIAs was evident. The mean percent increase, among all diameter points measured, was 11.7% at 24 months and 22.8% at 60 months (p < 0.001) with a nearly constant mean increase rate by 0.07 mm per month. The corresponding monthly elongation rate of total CIA length was 0.26 mm at 24 months and 0.34 mm at 5 years (p < 0.001). The respective monthly lengthening of CIAs' uncovered (from stent graft) segment was 0.10 and 0.15 mm, and the overall increase rate at 60 months was up to 53.9% (p < 0.001). A total of 20 EVAR-related events were recorded, and multivariate analysis revealed that CIA dilatation served as a significant and independent predictor of long-term EVAR failures, increasing the likelihood of adverse events by 2.8-fold. Conclusions: Analysis of long-term geometric CIA remodeling after a standard EVAR revealed a significant progression of aneurysmal disease in CIAs, which was associated with worsening EVAR outcomes and emphasizes the importance of a rigorous and extensive follow-up protocol to maintain the long-term EVAR effectiveness.

Effect of Chronic Kidney Disease on 30-Day Outcomes in Endovascular Repair of Complex Abdominal Aortic Aneurysm

BACKGROUND

Chronic kidney disease (CKD) has been identified as an independent predictor of poorer long-term prognosis after endovascular aneurysm repair (EVAR) for complex abdominal aortic aneurysm (AAA). However, its impact on short-term perioperative outcomes is conflicting, which can be important for preoperative risk stratification. This study aimed to evaluate the 30-day outcomes of patients with CKD following non-ruptured complex EVAR in a national registry.

METHODS

Patients who had EVAR for complex AAA were identified in ACS-NSQIP targeted database from 2012-2022. Complex AAA included juxtarenal, suprarenal, or pararenal proximal extent, Type IV thoracoabdominal aneurysm, and/or aneurysms treated with Zenith Fenestrated endograft. Exclusion criteria included age<18 years, ruptured AAA, acute intraoperative conversion to open, emergency presentation, and dialysis. Multivariable logistic regression was used to compare 30-day postoperative outcomes of CKD and non-CKD patients, where demographics, baseline characteristics, aneurysm diameter, distant aneurysm extent, anesthesia, and concomitant procedures were adjusted.

RESULTS

There were 695 (39.33%) and 1072 (60.67%) patients with and without CKD, respectively, who underwent EVAR for complex AAA. Patients with and without CKD have comparable 30-day mortality (aOR = 1.165, 95 CI = 0.646-2.099, P = 0.61). However, CKD patients had a higher risk of renal complications (aOR = 2.647, 95 CI = 1.399-5.009, P < 0.01) including higher progressive renal insufficiency (aOR = 3.707, 95 CI = 1.329-10.338, P = 0.01) and acute renal failure requiring renal replacement therapy (aOR = 2.533, 95 CI = 1.139-5.633, P = 0.02). All other 30-day outcomes were comparable between CKD and non-CKD patients.

CONCLUSION

Patients with CKD had similar 30-day mortality and morbidity rates but a higher risk of postoperative renal complications. Therefore, meticulous preoperative planning and postoperative management, which may include optimal hydration, appropriate contrast use, and close renal function monitoring, are essential for patients with CKD after complex EVAR.

Age-Disturbed Vascular Extracellular Matrix Links to Abdominal Aortic Aneurysms

Abdominal aortic aneurysm (AAA) is a common but life-threatening vascular condition in men at an advanced age. However, the underlying mechanisms of age-increased incidence and mortality of AAA remain elusive. Here, we performed RNA sequencing (RNA-seq) of mouse aortas from males (young: 3-month, n = 4 vs old: 23-month, n = 4) and integrated with the data sets of human aortas (young: 20-39, n = 47 vs old: 60-79 years, n = 92) from GTEx project and the data set (GSE183464) for AAA to search for age-shifted aortic aneurysm genes, their relevant biological processes, and signaling pathways. Angiotensin II-induced AAA in mice was used to verify the critical findings. We found 1 001 genes transcriptionally changed with ages in both mouse and human. Most age-increased genes were enriched intracellularly and the relevant biological processes included mitochondrial function and translational controls, whereas the age-decreased genes were largely localized in extracellular regions and cell periphery and the involved biological processes were associated with extracellular matrix (ECM). Fifty-one were known genes for AAA and found dominantly in extracellular region. The common age-shifted vascular genes and known aortic aneurysm genes had shared functional influences on ECM organization, apoptosis, and angiogenesis. Aorta with angiotensin II-induced AAA exhibited similar phenotypic changes in ECM to that in old mice. Together, we present a conserved transcriptional signature for aortic aging and provide evidence that mitochondrial dysfunction and the imbalanced ribosomal homeostasis act likely as driven-forces for aortic aging and age-disturbed ECM is the substrate for developing AAA.

Three-dimensional characterization of sex differences in abdominal aortic aneurysm progression via vascular deformation mapping

Although abdominal aortic aneurysms (AAA) are more common in men, women are at greater risk for AAA growth/rupture. Vascular deformation mapping (VDM) utilizes deformable image registration to qualify and quantify 3D-AAA growth using computed tomography angiograms (CTA). In this study we leveraged VDM to investigate sex differences in AAA growth patterns. Patients with infra-renal AAA and ≥ 2 CTA were identified. Males and females were matched for age, hypertension, and smoking history. Patient characteristics, maximum diameter (Dmax), and AAA volume were obtained. CTA images were segmented, and VDM was conducted to quantify 3D AAA growth rate per year (GR, cm/year). Statistical shape modeling was utilized to compute mean aneurysm shapes and 3D GR. Average GR was evaluated at specific regions of the aortic surface for males and females. Seventeen males and 17 females were matched. At the individual level, there were no sex differences in changes in Dmax or AAA volume. However, females had larger GR across the anterior and right lateral AAA (1.33 vs 0.89 and 1.56 vs 0.74 cm/year, respectively), despite no difference in posterior or left lateral AAA GR. Despite comparable changes in Dmax, AAA volume, and GR magnitude, women demonstrated a more eccentric, anterior-predominant, AAA growth pattern.

Association of cardiovascular disease and urate levels with aortic aneurysm: a bilateral mendelian randomization study

The aim of this study is to investigate the potential causal relationships between coronary artery disease (CAD), myocardial infarction (MI), urate levels, and aortic aneurysm (AA), abdominal aortic aneurysm (AAA), thoracic aortic aneurysm(TAA), aortic dissection (AD) in individuals of European ancestry. To examine the potential causal relationships between CAD, MI, and urate levels with AA, AAA, TAA, AD, respectively, we performed a two-sample Mendelian randomization (MR) analysis. Genetic instruments that reached genome-wide significance (p < 5 × 10 - 8) for risk factors were obtained from genome-wide association studies(GWASs) conducted on individuals of European origin. On the other hand, genetic instruments of AA, AAA, TAA or AD were chosen from the FinnGen cohort. The primary analysis employed the inverse-variance weighted MR method, while sensitivity analyses were conducted using MR-Egger, weighted median MR, MR pleiotropy residual sum and outlier, and Phenoscanner searching. In addition, we performed the MR-Egger intercept analysis to identify potential pleiotropy and utilized Cochran's Q statistics to evaluate heterogeneity. Additionally, we conducted bidirectional Mendelian randomization experiments to mitigate the potential influence of reverse causation. According to the results of our study, there were statistically significant higher risks for AA in relation to CAD/MI(odds ratio (OR) with 95% confidence interval (CI): 1.309 (1.150-1.490), and 1.255 (1.147-1.373). Similarly, there were statistically significant higher risks for AAA in relation to CAD and MI (OR with 95% CI: 1.383 (1.189-1.609), and 1.352 (1.178-1.552). The sensitivity analysis demonstrated that the causative effects of CAD/MI, and AA /AAA, were robust. A positive causal link was observed between CAD/MI, and AA/AAA. Nevertheless, no causal link was found between CAD, MI, urate levels, and TAA .

On the Importance of Including Cohesive Zone Models in Modelling Mixed-Mode Aneurysm Rupture

INTRODUCTION

The precise mechanism of rupture in abdominal aortic aneurysms (AAAs) has not yet been uncovered. The phenomenological failure criterion of the coefficient of proportionality between von Mises stress and tissue strength does not account for any mechanistic foundation of tissue fracture. Experimental studies have shown that arterial failure is a stepwise process of fibrous delamination (mode II) and kinking (mode I) between layers. Such a mechanism has not previously been considered for AAA rupture.

METHODS

In the current study we consider both von Mises stress in the wall, in addition to interlayer tractions and delamination using cohesive zone models. Firstly, we present a parametric investigation of the influence of a range of AAA anatomical features on the likelihood of elevated interlayer traction and delamination.

RESULTS

We observe in several cases that the location of peak von Mises stress and tangential traction coincide. Our simulations also reveal however, that peak von Mises and intramural tractions are not coincident for aneurysms with Length/Radius less than 2 (short high-curvature aneurysms) and for aneurysms with symmetric intraluminal thrombus (ILT). For an aneurysm with (L/R = 2.0), the peak σ vm moves slightly towards the origin while the peak T t is near the peak bulge with a separation distance of ~ 17 mm. Additionally, we present three patient-specific AAA models derived directly from CT scans, which also illustrate that the location of von Mises stress does not correlate with the point of interlayer delamination.

CONCLUSION

This study suggests that incorporating cohesive zone models into clinical based FE analyses may capture a greater proportion of ruptures in-silico.

Malnutrition is associated with adverse 30-day outcomes after endovascular repair of abdominal aortic aneurysm

BACKGROUND

Malnutrition is particularly pertinent in patients undergoing vascular surgery, who frequently present with a high burden of comorbidities and advanced age that can impede nutrient absorption. While previous studies have established that vascular surgery patients with malnutrition had poorer outcomes, the impact of nutritional status in patients undergoing endovascular aneurysm repair (EVAR) has not yet been investigated. Therefore, this study aimed to assess the effect of malnutrition on 30-day outcomes following non-ruptured EVAR.

METHODS

Patients who had infrarenal EVAR were identified in the ACS-NSQIP targeted database from 2012-2022. Exclusion criteria included age less than 18 years, ruptured aneurysm, and emergency. Malnutrition was defined as patients with preoperative weight loss of greater than 10% decrease in body weight in the 6 months immediately preceding the surgery. A 1:5 propensity-score matching was used to match demographics, baseline characteristics, aneurysm diameter, distant aneurysm extent, anesthesia, and concomitant procedures between patients with and without malnutrition. Thirty-day postoperative outcomes were examined.

RESULTS

There were 154 (0.94%) patients with malnutrition who went under non-ruptured EVAR. Meanwhile, 16,309 patients without malnutrition went under intact EVAR, where 737 of them were matched to all malnutrition patients. Malnourished patients had more comorbidity burdens. After propensity-score matching, patients with malnutrition had elevated but non-significant 30-day mortality (5.92% vs 2.99%, p = .09). However, malnutrition patients had higher risks of renal complications (2.63% vs 0.68%, p = .04), bleeding requiring transfusion (22.37% vs 14.38%, p = .02), and unplanned reoperation (11.18% vs 4.88%, p = .01), as well as longer length of stay (6.11 ± 7.91 vs 4.44 ± 6.22 days, p < .02).

CONCLUSION

Patients with malnutrition experienced higher rates of morbidity after non-ruptured EVAR. Targeting malnutrition could be a strategy for preventing complications after EVAR and proper preoperative malnutritional management could be warranted.

Preoperative Congestive Heart Failure Is Associated with Higher 30-Day Myocardial Infarction and Pneumonia after Endovascular Repair of Abdominal Aortic Aneurysm

INTRODUCTION

Preoperative congestive heart failure (CHF) is associated with higher postoperative mortality and complications in noncardiac surgery. However, postoperative outcomes for patients with preoperative CHF undergoing endovascular aneurysm repair (EVAR) have not been thoroughly established. This study evaluated the effect of preoperative CHF on 30-day outcomes following nonemergent intact EVAR using a large-scale national registry.

METHODS

Patients who had infrarenal EVAR were identified in the ACS-NSQIP database from 2012 to 2022. A 1:5 propensity-score matching was used to match demographics, baseline characteristics, aneurysm diameter, distant aneurysm extent, anesthesia, and concomitant procedures between patients with and without preoperative CHF. Thirty-day postoperative outcomes were examined.

RESULTS

467 (2.84%) CHF patients underwent intact EVAR. Meanwhile, 15,996 non-CHF patients underwent EVAR, where 2,248 of them were matched to all CHF patients. Patients with and without preoperative CHF had comparable 30-day mortality (3.02% vs. 2.62%, p = 0.64). However, CHF patients had higher myocardial infarction (3.02% vs. 1.47%, p = 0.03), pneumonia (3.23% vs. 1.73%, p = 0.04), 30-day readmission (p = 0.01), and longer length of stay (p < 0.01).

CONCLUSION

While patients with and without preoperative CHF had comparable 30-day mortality rates, those with CHF faced higher risks of cardiopulmonary complications. Effective management of preoperative CHF may help prevent postoperative complications in these patients.

Ruptured AAA: bridging the gap between international guidelines and local clinical realities

BACKGROUND

Treatment of asymptomatic Abdominal Aortic Aneurysms (AAA) presents a clinical challenge, requiring a delicate balance between rupture risk, patient comorbidities, and intervention-related complications. International guidelines recommend intervention for specific AAA size thresholds, but these are based on historical trials with limited female representation. We aimed to analyse disease characteristics, AAA size at rupture, and intervention outcomes in patients with ruptured AAA from 2009 to 2023 to investigate the gap between guidelines and local realities.

METHODS

This single-centre retrospective cohort study analysed electronic health records of patients treated for a ruptured AAA, excluding those who were managed palliatively. The study assessed patients' demographics, risk factors, comorbidities, clinical presentation, radiological characteristics, and outcomes.

RESULTS

Of 164 patients (41 females, 123 males, median age 73.5), 93.3% presented with abdominal or back pain. The median AAA size at rupture was 8.0 cm in males and 7.6 cm in females. No significant correlations were found between demographic characteristics, risk factors, AAA size, repair modality, and outcomes. Trends show a decline in AAA prevalence and rupture rates, aligning with global health initiatives. Post-intervention survival rates at 30 days were 70.7% (67.5% in males and 80.0% in females), and at 2 years were 65.85% (61.7% in males and 70.0% in females).

CONCLUSION

Evolving AAA trends and improved post-intervention survival rates warrant a critical reassessment of existing intervention recommendations. Adjusting intervention thresholds to larger sizes may be justified to optimise the risk-benefit ratio.

Preoperative anemia is a risk factor for worse 30-day outcomes in both open and endovascular repair of non-ruptured infrarenal abdominal aortic aneurysm

BACKGROUND

Anemia is a highly prevalent condition potentially linked to chronic inflammation. Preoperative anemia is an independent risk factor across many surgical fields. However, the relationship between anemia and abdominal aortic aneurysm (AAA) repair outcomes remains unclear. This study aimed to examine the effects of preoperative anemia on 30-day outcomes of non-ruptured infrarenal AAA repair.

METHODS

Patients who underwent open surgical repair (OSR) and endovascular aneurysm repair (EVAR) for infrarenal AAA were identified in National Surgical Quality Improvement Program (NSQIP) targeted databases from 2012 to 2021. Anemia was defined as preoperative hematocrit less than 39% in males and 36% in females. Multivariable logistic regression was used to compare 30-day perioperative outcomes between anemic and non-anemic patients, adjusting for demographics, comorbidities, indications, aneurysm extents, operation time, and surgical approaches.

RESULTS

There were 408 (22.13%) anemic and 1436 (77.88%) non-anemic patients who underwent OSR for non-ruptured AAA, while 3586 (25.20%) patients with and 10,644 (74.80%) without anemia underwent EVAR. In both OSR and EVAR, anemic patients had higher risks of bleeding requiring transfusion (OSR, aOR = 2.446, p < .01; EVAR, aOR = 3.691, p < .01), discharge not to home (OSR, aOR = 1.385, p = .04; EVAR, aOR = 1.27, p < .01), and 30-day readmission (OSR, aOR = 1.99, p < .01; EVAR, aOR = 1.367, p < .01). Also, anemic patients undergoing OSR had higher pulmonary events (aOR = 2.192, p < .01), sepsis (aOR = 2.352, p < .01), and venous thromboembolism (aOR = 2.913, p = .01), while in EVAR, anemic patients had higher mortality (aOR = 1.646, p = .01), cardiac complications (aOR = 1.39, p = .04), renal dysfunction (aOR = 1.658, p = .02), and unplanned reoperation (aOR = 1.322, p = .01). Moreover, in both OSR and EVAR, anemic patients had longer hospital length of stay (p < .01).

CONCLUSION

In OSR and EVAR, preoperative anemia was independently associated with worse 30-day outcomes. Preoperative anemia could be a useful marker for risk stratification for patients undergoing infrarenal AAA repair.

Acute Intraoperative Conversion from Endovascular to Open vs Planned Open Operation for Abdominal Aortic Aneurysm: A Propensity-Score Matched Study from the American College of Surgeons NSQIP-Targeted Database

BACKGROUND

Evaluating outcomes for acute intraoperative conversion to open surgery during endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA) was difficult due to low incidence. This study aimed to compare 30-day outcomes between patients with acute intraoperative conversion during EVAR and planned open surgery, and to identify risk factors associated with acute conversion.

STUDY DESIGN

Patients who underwent EVAR or planned open AAA repair were identified in American College of Surgeons NSQIP-targeted databases from 2012 to 2021. Patients with acute intraoperative conversion during EVAR were selected. A 1:3 propensity-score matching was used to match demographics, baseline characteristics, surgical indications, aneurysm size and extent, and emergency cases between the conversion open and planned open groups. Thirty-day postoperative outcomes were assessed.

RESULTS

Of 20,566 EVAR cases, 177 (0.86%) had acute intraoperative conversion to open surgery. The conversion open group was matched to 504 of 5,249 planned open patients. Conversion open and planned open groups had comparable 30-day mortality (23.43% vs 17.46%, p = 0.09) and organ system complications, including major adverse cardiovascular event (14.86% vs 10.71%, p = 0.17), pulmonary complications (17.71% vs 24.01%, p = 0.09), and renal complications (8.57% vs 11.11%, p = 0.39). The conversion open group had lower bleeding requiring transfusion (48.57% vs 75.60%, p < 0.01), shorter operation time (p < 0.01), and shorter length of stay (p < 0.01). Other postoperative outcomes did not differ. Risk factors associated with acute intraoperative conversion included ruptured aneurysm with or without hypotension. Protective factors included hypertension and aortic distal aneurysm extent.

CONCLUSIONS

Although this study does not endorse a universal "EVAR first" strategy for all patients with AAA, EVAR can be attempted first in eligible patients with AAA. Even when EVAR is unsuccessful, intraoperative conversion to open surgery still appears to be safe compared with planned open repair.

A prospective longitudinal study of risk factors for abdominal aortic aneurysm

The aim of this study was to identify risk factors for abdominal aortic aneurysm (AAA) from the largest Welsh screening cohort to date. Patients were recruited from 1993 (to 2015) as part of the South East Wales AAA screening programme through general practitioners. Demographic data and risk factors were collected by means of a self-report questionnaire. Statistical tests were performed to determine whether associations could be observed between AAA and potential risk factors. Odds ratios (OR) were also calculated for each of the risk factors identified. A total of 6879 patients were included in the study. Two hundred and seventy-five patients (4.0%) presented with AAA, of which 16% were female and 84% were male. Patients with AAA were older than the (no AAA) control group (p < 0.0001). The following risk factors were identified for AAA: family history of AAA (p < 0.0001); history of vascular surgery (p < 0.0001), cerebrovascular accident (p < 0.0001), coronary heart disease (p < 0.0001), diabetes (p < 0.0001), medication (p = 0.0018), claudication (p < 0.0001), smoking history (p = 0.0001) and chronic obstructive pulmonary disorder (p = 0.0007). AAA is associated with classical vascular risk factors, in addition to other less-well-documented risk factors including previous vascular surgery. These findings have practical implications with the potential to improve future clinical screening of patients in order to reduce AAA mortality.

Roles and Mechanisms of miRNAs in Abdominal Aortic Aneurysm: Signaling Pathways and Clinical Insights

PURPOSE OF REVIEW

Abdominal aortic aneurysm refers to a serious medical condition that can cause the irreversible expansion of the abdominal aorta, which can lead to ruptures that are associated with up to 80% mortality. Currently, surgical and interventional procedures are the only treatment options available for treating abdominal aortic aneurysm patients. In this review, we focus on the upstream and downstream molecules of the microRNA-related signaling pathways and discuss the roles, mechanisms, and targets of microRNAs in abdominal aortic aneurysm modulation to provide novel insights for precise and targeted drug therapy for the vast number of abdominal aortic aneurysm patients.

RECENT FINDINGS

Recent studies have highlighted that microRNAs, which are emerging as novel regulators of gene expression, are involved in the biological activities of regulating abdominal aortic aneurysms. Accumulating studies suggested that microRNAs modulate abdominal aortic aneurysm development through various signaling pathways that are yet to be comprehensively summarized. A total of six signaling pathways (NF-κB signaling pathway, PI3K/AKT signaling pathway, MAPK signaling pathway, TGF-β signaling pathway, Wnt signaling pathway, and P53/P21 signaling pathway), and a total of 19 miRNAs are intimately associated with the biological properties of abdominal aortic aneurysm through targeting various essential molecules. MicroRNAs modulate the formation, progression, and rupture of abdominal aortic aneurysm by regulating smooth muscle cell proliferation and phenotype change, vascular inflammation and endothelium function, and extracellular matrix remodeling. Because of the broad crosstalk among signaling pathways, a comprehensive analysis of miRNA-mediated signaling pathways is necessary to construct a well-rounded upstream and downstream regulatory network for future basic and clinical research of AAA therapy.

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.

Construction of the circRNA-miRNA-mRNA axis based on ferroptosis-related gene AKR1C1 to explore the potential pathogenesis of abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a cardiovascular disease that seriously threatens human health and brings huge economic burden. At present, its pathogenesis remains unclear and its treatment is limited to surgical treatment. With the deepening and analysis of studies on the mechanism of ferroptosis, a new idea has been provided for the clinical management of AAA patients, including diagnosis, treatment and prevention. Therefore, this paper aims to construct a competitive endogenous RNA (ceRNA) regulatory axis based on ferroptosis to preliminarily explore the pathogenesis and potential therapeutic targets of AAA. We obtained upregulated and downregulated ferroptosis-related DEGs (FRGs) from GSE144431 dataset and 60 known ferroptosis-related genes. Pearson correlation analysis was used to find aldoketone reductase 1C (AKR1C1) in AAA samples. Enrichment analysis of these genes was performed via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Correlation test between immune cells and AKR1C1 was investigated through single-sample gene set enrichment analysis (ssGSEA). The AKR1C1-miRNA pairs were predicted by the TargetScan database and miRWalk database. Circular RNA (CircRNA)-miRNA pairs were selected by the CircInteractome database. Overlapping miRNA between circRNA-miRNA and AKR1C1-miRNA pairs was visualized by Venn diagram. Finally, the circRNA-miRNA-mRNA axis was constructed by searching for upstream circRNA and downstream mRNA of overlapping miRNA. Only one downregulated AKR1C1 gene was found in GSE144431 and 60 ferroptosis-related genes. Functional Enrichment and Pathway Analysis of AKR1C1-related genes were further explored, and it was observed that they were mainly enriched in "response to oxidative stress," "glutathione biosynthetic process" and "nonribosomal peptide biosynthetic process," "Ferroptosis," "Glutathione metabolism" and "Chemical carcinogenesis-reactive oxygen species." They were also found to be significantly associated with most immune cells, including Activated Dendritic cells, CD56dim Natural killer cells, Gamma Delta T cells, Immature B cells, Plasmacytoid dendritic cell, Type 2 T helper cell, Activated CD4 T cell and Type 1 T helper cell. Has_circ_0005073-miRNA-543 and AKR1C1-miRNA-543 were identified by Online Database analysis. Therefore, we have established the has_circ_0005073/miRNA-543/AKR1C1 axis in AAA. We found AKR1C1 was differentially expressed between normal and AAA groups. Based on AKR1C1, we constructed the has_circ_0005073/miRNA-543/AKR1C1 axis to analyze AAA.

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.

Measurement of Abdominal Aortic Aneurysm Strain Using MR Deformable Image Registration: Accuracy and Relationship to Recent Aneurysm Progression

BACKGROUND

Management of asymptomatic abdominal aortic aneurysm (AAA) based on maximum aneurysm diameter and growth rate fails to preempt many ruptures. Assessment of aortic wall biomechanical properties may improve assessment of progression and rupture risk. This study aimed to assess the accuracy of AAA wall strain measured by cine magnetic resonance imaging (MRI) deformable image registration (MR strain) and investigate its relationship with recent AAA progression.

METHODS

The MR strain accuracy was evaluated in silico against ground truth strain in 54 synthetic MRIs generated from a finite element model simulation of an AAA patient's abdomen for different aortic pulse pressures, tissue motions, signal intensity variations, and image noise. Evaluation included bias with 95% confidence interval (CI) and correlation analysis. Association of MR strain with AAA growth rate was assessed in 25 consecutive patients with >6 months of prior surveillance, for whom cine balanced steady-state free-precession imaging was acquired at the level of the AAA as well as the proximal, normal-caliber aorta. Univariate and multivariate regressions were used to associate growth rate with clinical variables, maximum AAA diameter (D max ), and peak circumferential MR strain through the cardiac cycle. The MR strain interoperator variability was assessed using bias with 95% CI, intraclass correlation coefficient, and coefficient of variation.

RESULTS

In silico experiments revealed an MR strain bias of 0.48% ± 0.42% and a slope of correlation to ground truth strain of 0.963. In vivo, AAA MR strain (1.2% ± 0.6%) was highly reproducible (bias ± 95% CI, 0.03% ± 0.31%; intraclass correlation coefficient, 97.8%; coefficient of variation, 7.14%) and was lower than in the nonaneurysmal aorta (2.4% ± 1.7%). D max ( β = 0.087) and MR strain ( β = -1.563) were both associated with AAA growth rate. The MR strain remained an independent factor associated with growth rate ( β = -0.904) after controlling for D max .

CONCLUSIONS

Deformable image registration analysis can accurately measure the circumferential strain of the AAA wall from standard cine MRI and may offer patient-specific insight regarding AAA progression.

A highly selective mPGES-1 inhibitor to block abdominal aortic aneurysm progression in the angiotensin mouse model

Abdominal aortic aneurysm (AAA) is a deadly, permanent ballooning of the aortic artery. Pharmacological and genetic studies have pointed to multiple proteins, including microsomal prostaglandin E2 synthase-1 (mPGES-1), as potentially promising targets. However, it remains unknown whether administration of an mPGES-1 inhibitor can effectively attenuate AAA progression in animal models. There are still no FDA-approved pharmacological treatments for AAA. Current research stresses the importance of both anti-inflammatory drug targets and rigor of translatability. Notably, mPGES-1 is an inducible enzyme responsible for overproduction of prostaglandin E2 (PGE2)-a well-known principal pro-inflammatory prostanoid. Here we demonstrate for the first time that a highly selective mPGES-1 inhibitor (UK4b) can completely block further growth of AAA in the ApoE-/- angiotensin (Ang)II mouse model. Our findings show promise for the use of a mPGES-1 inhibitor like UK4b as interventional treatment of AAA and its potential translation into the clinical setting.

Risk factors and mortality in dialysis patients with abdominal aortic aneurysm: A retrospective cohort study

In the general population, abdominal aortic aneurysm (AAA) is synonymous with vascular disease and associated with increased mortality. Vascular disease is common in end-stage renal disease (ESRD) patients on dialysis, but there is limited information on AAA in this population. To address this issue, we queried the United States Renal Data System for risk factors associated with a diagnosis of AAA as well as the impact of AAA on ESRD patient survival. Incident dialysis patients from 2005 to 2014 with AAA and other clinical comorbidities were identified using ICD-9 and ICD-10 codes. Time to death was defined using the time from the start of dialysis to the date of death or to December 31, 2015. Cox proportional hazards (CPH) modeling was used to determine the adjusted hazard ratio (aHR) and 95% confidence intervals (CI) for death. From a total cohort of 820,826, we identified 21,631 subjects with a diagnosis of AAA. When compared to patients without AAA, AAA patients were older and more likely to be of white race and male gender, have a higher mean Charlson comorbidity index (CCI), have hypertension as the ESRD etiology, and use tobacco. Although a bivariate CPH model showed that AAA patients had an increased mortality risk compared to patients without the diagnosis, in the final CPH model, AAA patients had a decreased risk of mortality (aHR = 0.83, 95% CI 0.81-0.84) due to confounding with age. These results suggest that AAA is not associated with increased risk of death in ESRD patients after controlling for various demographic and clinical risk factors.

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.

Body mass index and the risk of abdominal aortic aneurysm presence and post-operative mortality: a systematic review and dose-response meta-analysis

BACKGROUND

The clinical data regarding the relationships between body mass index (BMI) and abdominal aortic aneurysm (AAA) are inconsistent, especially for the obese and overweight patients. The aims of this study were to determine whether obesity is associated with the presence of AAA and to investigate the quantitative relationship between BMI and the risk of AAA presence and post-operative mortality.

MATERIALS AND METHODS

PubMed, Web of Science and Embase databases were used to search for pertinent studies updated to December 2023. The pooled relative risk (RR) with 95% confidence interval (CI) was estimated by conventional meta-analysis based on random effects model. Dose-response meta-analyses using robust-error meta-regression (REMR) model were conducted to quantify the associations between BMI and AAA outcome variables. Subgroup analysis, sensitivity analysis and publication bias analysis were performed according to the characteristics of participants.

RESULTS

18 studies were included in our study. The meta-analysis showed a higher prevalence of AAA with a RR of 1.07 in patients with obesity. The dose-response meta-analysis revealed a non-linear relationship between BMI and the risk of AAA presence. A "U" shape curve reflecting the correlation between BMI and the risk of post-operative mortality in AAA patients was also uncovered, suggesting the "safest" BMI interval [28.55, 31.05] with the minimal RR.

CONCLUSIONS

Obesity is positively but nonlinearly correlated with the increased risk of AAA presence. BMI is related to AAA post-operative mortality in a "U" shaped curve, with the lowest RR observed among patients suffering from overweight and obesity. These findings offer a preventive strategy for AAA morbidity and provide guidance for improving the prognosis in patients undergone AAA surgical repair.

One-time screening for abdominal aortic aneurysm in Ontario, Canada: a model-based cost-utility analysis

BACKGROUND

Screening programs for abdominal aortic aneurysm (AAA) are not available in Canada. We sought to determine the effectiveness and costutility of AAA screening in Ontario.

METHODS

We compared one-time ultrasonography-based AAA screening for people aged 65 years to no screening using a fully probabilistic Markov model with a lifetime horizon. We estimated life-years, quality-adjusted life-years (QALYs), AAA-related deaths, number needed to screen to prevent 1 AAA-related death and costs (in Canadian dollars) from the perspective of the Ontario Ministry of Health. We retrieved model inputs from literature, Statistics Canada, and the Ontario Case Costing Initiative.

RESULTS

Screening reduced AAA-related deaths by 84.9% among males and 81.0% among females. Compared with no screening, screening resulted in 0.04 (18.96 v. 18.92) additional life-years and 0.04 (14.95 v. 14.91) additional QALYs at an incremental cost of $80 per person among males. Among females, screening resulted in 0.02 (21.25 v. 21.23) additional life-years and 0.01 (16.20 v. 16.19) additional QALYs at an incremental cost of $11 per person. At a willingness-to-pay of $50 000 per year, screening was cost-effective in 84% (males) and 90% (females) of model iterations. Screening was increasingly cost-effective with higher AAA prevalence.

INTERPRETATION

Screening for AAA among people aged 65 years in Ontario was associated with fewer AAA-related deaths and favourable cost-effectiveness. To maximize QALY gains per dollar spent and AAA-related deaths prevented, AAA screening programs should be designed to ensure that populations with high prevalence of AAA participate.

Female-Specific Considerations in Aortic Health and Disease

The aorta plays a central role in the modulation of blood flow to supply end organs and to optimize the workload of the left ventricle. The constant interaction of the arterial wall with protective and deleterious circulating factors, and the cumulative exposure to ventriculoarterial pulsatile load, with its associated intimal-medial changes, are important players in the complex process of vascular aging. Vascular aging is also modulated by biomolecular processes such as oxidative stress, genomic instability, and cellular senescence. Concomitantly with well-established cardiometabolic and sex-specific risk factors and environmental stressors, arterial stiffness is associated with cardiovascular disease, which remains the leading cause of morbidity and mortality in women worldwide. Sexual dimorphisms in aortic health and disease are increasingly recognized and explain-at least in part-some of the observable sex differences in cardiovascular disease, which will be explored in this review. Specifically, we will discuss how biological sex affects arterial health and vascular aging and the implications this has for development of certain cardiovascular diseases uniquely or predominantly affecting women. We will then expand on sex differences in thoracic and abdominal aortic aneurysms, with special considerations for aortopathies in pregnancy.

Ruptured abdominal aortic aneurysm discovered by pocket-sized ultrasound in a low resource setting: a case report

BACKGROUND

Abdominal aortic aneurysm (AAA) is a life-threatening condition characterized by the weakening and dilation of the abdominal aorta. AAA primarily affects men, smokers, and the elderly, with rupture being a fatal complication. While point-of-care ultrasound (POCUS) is valuable in diagnosing AAA, the role of using pocket-sized ultrasound in a low resource setting remains less explored. This case report presents a unique instance of a suspected ruptured AAA diagnosed using pocket-sized ultrasound in an emergency department (ED) situated in a low resource setting where ultrasound machines are absent, and emergency physicians lack proficiency in ultrasound usage.

CASE PRESENTATION

A 78-year-old man with a history of hypertension and bladder cancer presented to the ED with suprapubic pain. Initial evaluation showed no concerning findings. However, the next day, he collapsed, became unconscious, and experienced a cardiac arrest. Despite resuscitation efforts, the patient's condition deteriorated. POCUS revealed an 8-cm dilated abdominal aorta with an intimal flap, indicative of a dissecting AAA and a substrate for AAA rupture. Unfortunately, the patient died despite resuscitation efforts.

CONCLUSION

This case highlights the importance of considering AAA in patients with risk factors and abdominal pain in a low resource setting. POCUS using a pocket-sized ultrasound can aid in early AAA detection, potentially preventing rupture through preemptive vascular intervention. Emergency departments should prioritize ultrasound availability, and emergency physicians should be proficient in its use.

Blood-wall fluttering instability as a physiomarker of the progression of thoracic aortic aneurysms

The diagnosis of aneurysms is informed by empirically tracking their size and growth rate. Here, by analysing the growth of aortic aneurysms from first principles via linear stability analysis of flow through an elastic blood vessel, we show that abnormal aortic dilatation is associated with a transition from stable flow to unstable aortic fluttering. This transition to instability can be described by the critical threshold for a dimensionless number that depends on blood pressure, the size of the aorta, and the shear stress and stiffness of the aortic wall. By analysing data from four-dimensional flow magnetic resonance imaging for 117 patients who had undergone cardiothoracic imaging and for 100 healthy volunteers, we show that the dimensionless number is a physiomarker for the growth of thoracic ascending aortic aneurysms and that it can be used to accurately discriminate abnormal versus natural growth. Further characterization of the transition to blood-wall fluttering instability may aid the understanding of the mechanisms underlying aneurysm progression in patients.

CD73 deficiency does not aggravate angiotensin II-induced aortic inflammation in mice

Vascular inflammation plays a key role in the development of aortic diseases. A potential novel target for treatment might be CD73, an ecto-5'-nucleotidase that generates anti-inflammatory adenosine in the extracellular space. Here, we investigated whether a lack of CD73 results in enhanced aortic inflammation. To this end, angiotensin II was infused into wildtype and CD73-/- mice over 10 days. Before and after infusion, mice were analyzed using magnetic resonance imaging, ultrasound, flow cytometry, and histology. The impact of age and gender was investigated using female and male mice of three and six months of age, respectively. Angiotensin II infusion led to increased immune cell infiltration in both genotypes' aortae, but depletion of CD73 had no impact on immune cell recruitment. These findings were not modified by age or sex. No substantial difference in morphological or functional characteristics could be detected between wildtype and CD73-/- mice. Interestingly, the expression of CD73 on neutrophils decreased significantly in wildtype mice during treatment. In summary, we have found no evidence that CD73 deficiency affects the onset of aortic inflammation. However, as CD73 expression decreased during disease induction, an increase in CD73 by pharmaceutical intervention might result in lower vascular inflammation and less vascular disease.

Dynamic Contrast-Enhanced MRI in Abdominal Aortic Aneurysms as a Potential Marker for Disease Progression

BACKGROUND

Abdominal aortic aneurysms (AAAs) may rupture before reaching maximum diameter (Dmax ) thresholds for repair. Aortic wall microvasculature has been associated with elastin content and rupture sites in specimens, but its relation to progression is unknown.

PURPOSE

To investigate whether dynamic contrast-enhanced (DCE) MRI of AAA is associated with Dmax or growth.

STUDY TYPE

Prospective.

POPULATION

A total of 27 male patients with infrarenal AAA (mean age ± standard deviation = 75 ± 5 years) under surveillance with DCE MRI and 2 years of prior follow-up intervals with computed tomography (CT) or MRI.

FIELD STRENGTH/SEQUENCE

A 3-T, dynamic three-dimensional (3D) fast gradient-echo stack-of-stars volumetric interpolated breath-hold examination (Star-VIBE).

ASSESSMENT

Wall voxels were manually segmented in two consecutive slices at the level of Dmax . We measured slope to 1-minute and area under the curve (AUC) to 1 minute and 4 minutes of the signal intensity change postcontrast relative to that precontrast arrival, and, Ktrans , a measure of microvascular permeability, using the Patlak model. These were averaged over all wall voxels for association to Dmax and growth rate, and, over left/right and anterior/posterior quadrants for testing circumferential homogeneity. Dmax was measured orthogonal to the aortic centerline and growth rate was calculated by linear fit of Dmax measurements.

STATISTICAL TESTS

Pearson correlation and linear mixed effects models. A P value <0.05 was considered statistically significant.

RESULTS

In 44 DCE MRIs, mean Dmax was 45 ± 7 mm and growth rate in 1.5 ± 0.4 years of prior follow-up was 1.7 ± 1.2 mm per year. DCE measurements correlated with each other (Pearson r = 0.39-0.99) and significantly differed between anterior/posterior versus left/right quadrants. DCE measurements were not significantly associated with Dmax (P = 0.084, 0.289, 0.054 and 0.255 for slope, AUC at 1 minute and 4 minutes, and Ktrans , respectively). Slope and 4 minutes AUC significantly associated with growth rate after controlling for Dmax .

CONCLUSION

Contrast uptake may be increased in lateral aspects of the AAA. Contrast enhancement 1-minute slope and 4-minutes AUC may be associated with a period of recent AAA growth that is independent of Dmax .

EVIDENCE LEVEL

3.

TECHNICAL EFFICACY

Stage 2.

Impact of patient demographics and intraoperative characteristics on abdominal aortic aneurysm sac following endovascular repair

BACKGROUND

Endovascular aortic repair (EVAR) has become the preferred treatment for abdominal aortic aneurysm (AAA). Its main aim is to seal the perfusion of the aneurysmal sac and, thus, induce sac regression and subsequent aortic remodelling. Aneurysmal sac regression has been linked to the short- and long-term clinical outcomes post-EVAR. It has also been shown to be influenced by endograft device choice, with several of these available commercially. This review summarises and discusses current evidence on the influence of pre- and intraoperative factors on sac regression. Additionally, this review aims to highlight the device-specific variations in sac regression to provide an overall holistic approach to treating AAAs with EVAR.

METHODS

A comprehensive literature search was conducted using multiple electronic databases to identify and extract relevant data.

RESULTS

Female sex, >70 mm original sac diameters, higher pre-procedural fibrinogen levels, smoking and low intra-aneurysmal pressure were found to positively impact sac regression. Whereas renal impairment, ischemic heart disease, high intra-aneurysmal pressure and aneurysm neck thrombus negatively influenced sac regression. Patent lumbar arteries, age, statins and hypercholesterolaemia displayed conflicting evidence regarding sac regression. Regarding the EVAR endografts compared, newer generation devices such as the Anaconda mainly showed the most optimal results.

CONCLUSION

Sac regression following EVAR in AAA is an important prognostic factor for morbidity and mortality. Nevertheless, several pre- and intraoperative factors can have an influence on sac regression. Therefore, it is necessary to take them into account when assessing AAA patients for EVAR to optimise outcomes. The choice of EVAR stent-graft can also affect sac regression, with evidence suggesting that the Fenestrated Anaconda is associated with the most favourable results.

Patient longevity and survival with custom-made endovascular solutions: The Fenestrated AnacondaTM approach

BACKGROUND

Endovascular aortic repair (EVAR) has become the mainstay treatment for abdominal aortic aneurysms and is associated with excellent clinical outcomes. However, there remains a risk of complications requiring reintervention. Several EVAR devices exist commercially, yet, the Terumo Aortic Fenestrated Anaconda™ has demonstrated outstanding results. The main scope of this study is to evaluate survival/longevity, target vessel patency (TVP), endograft migration and reintervention following Fenestrated Anaconda™ implantation and discuss relevant literature.

METHODS

The current study represents a 9-year cross-sectional international analysis of custom-made Fenestrated Anaconda™ device. For the statistical analysis, SPSS 28 for Windows and R was utilised. Pearson Chi-Square analysis was used to assess differences in cumulative distribution frequencies between variables. Statistical significance for all two-tailed tests was set at p < 0.05.

RESULTS

A total of 5058 patients received the Fenestrated Anaconda™ endograft. The Fenestrated Anaconda™ was indicated either due to complex anatomy for competitor devices (n = 3891, 76.9%) or based on surgeon preference (n = 1167, 23.1%). Both survival and TVP were 100% during the first 6 postoperative years but dropped to 77.1% and 81% thereafter. In the complex anatomy indication group, cumulative survival and TVP were both 100% until year 7 post-EVAR when they decreased to 82.8% and 75.7%. In the other indication group, survival and TVP were also 100% during the first 6 years but plateaued at 58.1% and 98.8% in years 7-9 of follow-up. No cases of endograft migration and reintervention were recorded.

CONCLUSION

The Fenestrated Anaconda™ has been proven across the literature to be a highly effective EVAR endograft, as it has demonstrated excellent survival/longevity and TVP as well as minimal endograft migration and reintervention.

Endovascular solutions for abdominal aortic aneurysms: A comparative review of clinical outcomes with custom-made endografts

BACKGROUND

The introduction of endovascular aortic repair has revolutionised the treatment of abdominal aortic aneurysms, replacing open surgical repair for the majority of elective cases due to its optimal morbidity and mortality. Several endovascular aortic repair stent grafts exist commercially, one of which is the Fenestrated Anaconda™ by Terumo Aortic which benefits from a very innovative design, unique custom-made approach and highly favourable results.

AIMS

The main scope of this narrative review is to provide a comprehensive overview of endovascular aortic repair clinical outcomes using the Fenestrated Anaconda™ stent-graft and comparing these with its market competitor, Zenith. This review will also examine the evidence in the literature on the Anaconda™'s custom-made approach.

METHODS

A comprehensive literature was conducted on several search engines including PubMed, Google Scholar, Ovid, Scopus and Embase to collate the evidence in the literature on clinical outcomes achieved with the Fenestrated Anaconda™ and Zenith including, but not limited to, survival, technical success, target vessel patency, endoleak, reintervention and aneurysm sac regression.

RESULTS

The Fenestrated Anaconda™ is associated with excellent results, including highly favourable survival, technical and clinical success and target vessel patency rates, very low need for reintervention or conversion, and minimal incidence of complications such as endoleak and endograft migration. The Fenestrated Anaconda™ also drives significant sac regression and aortic remodelling. In addition, its unique custom-made approach enables it to treat highly complex aortic anatomy as well as to 'rescue' failed competitor grafts.

CONCLUSION

The Fenestrated Anaconda™ has proven that it is a very safe, highly applicable and extremely effective device used for complex aortic and/or iliac pathology based on its novel design and outstanding track record of clinical outcomes.

Status of diagnosis and therapy of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are characterized by localized dilation of the abdominal aorta. They are associated with several serious consequences, including compression of adjacent abdominal organs, pain, treatment-related financial expenditure. The main complication of AAA is aortic rupture, which is responsible for about 200,000 deaths per year worldwide. An increasing number of researchers are dedicating their efforts to study AAA, resulting in significant progress in this field. Despite the commendable progress made thus far, there remains a lack of established methods to effectively decelerate the dilation of aneurysms. Therefore, further studies are imperative to expand our understanding and enhance our knowledge concerning AAAs. Although numerous factors are known to be associated with the occurrence and progression of AAA, the exact pathway of development remains unclear. While asymptomatic at most times, AAA features a highly unpredictable disease course, which could culminate in the highly deadly rupture of the aneurysmal aorta. Current guidelines recommend watchful waiting and lifestyle adjustment for smaller, slow-growing aneurysms, while elective/prophylactic surgical repairs including open repair and endovascular aneurysm repair are recommended for larger aneurysms that have grown beyond certain thresholds (55 mm for males and 50 mm for females). The latter is a minimally invasive procedure and is widely believed to be suited for patients with a poor general condition. However, several concerns have recently been raised regarding the postoperative complications and possible loss of associated survival benefits on it. In this review, we aimed to highlight the current status of diagnosis and treatment of AAA by an in-depth analysis of the findings from literatures.

Dysregulations of Key Regulators of Angiogenesis and Inflammation in Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a chronic vascular disease caused by localized weakening and broadening of the abdominal aorta. AAA is a clearly underdiagnosed disease and is burdened with a high mortality rate (65-85%) from AAA rupture. Studies indicate that abnormal regulation of angiogenesis and inflammation contributes to progression and onset of this disease; however, dysregulations in the molecular pathways associated with this disease are not yet fully explained. Therefore, in our study, we aimed to identify dysregulations in the key regulators of angiogenesis and inflammation in patients with AAA in peripheral blood mononuclear cells (using qPCR) and plasma samples (using ELISA). Expression levels of ANGPT1, CXCL8, PDGFA, TGFB1, VEGFB, and VEGFC and plasma levels of TGF-alpha, TGF-beta 1, VEGF-A, and VEGF-C were found to be significantly altered in the AAA group compared to the control subjects without AAA. Associations between analyzed factors and risk factors or biochemical parameters were also explored. Any of the analyzed factors was associated with the size of the aneurysm. The presented study identified dysregulations in key angiogenesis- and inflammation-related factors potentially involved in AAA formation, giving new insight into the molecular pathways involved in the development of this disease and providing candidates for biomarkers that could serve as diagnostic or therapeutic targets.

An Epidemiologic Study of the Incidence and Mortality of Abdominal Aortic Aneurysms in Koreans Aged ≥50 Years from 2009 to 2018 Based on a National Database

Large-scale population studies of the incidence of and mortality from abdominal aortic aneurysm (AAA) are needed to develop healthcare policies and priorities. The aim of this study was to estimate the incidence of AAA and the all-cause mortality from it among Koreans aged ≥50 years from 2009 to 2018 using data from the Korean National Health Insurance System Database. The crude and standardized incidence and all-cause mortality of the disease among patients with unruptured AAA were calculated. A total of 73,933 AAA patients were identified. The overall incidence of AAA in adults ≥50 years during the study period was 37.5 per 100,000 population (49.7 per 100,000 in men and 26.8 per 100,000 in women), with an increase from 32.33 per 100,000 persons in 2009 to 46.85 per 100,000 in 2018. The crude all-cause mortality rate of patients with untreated AAA was 21.26/100 person-years in 2009 and 8.87/100 person-years in 2018, with decreasing trends observed both in men and women. This nationwide study showed that the incidence of AAA in Koreans aged ≥50 years in 2018 was 63.40 per 100,000 in men and 32.07 per 100,000 in women. The overall rates were 0.06% and 0.03%, respectively, with an increasing trend. Mortality has decreased in both treated and untreated patients. The observed increase in incidence suggests a rising burden of AAA in the Korean population, particularly among men. The decreasing mortality rates may indicate improvements in the management and treatment of AAA over the study period.

The Global and Regional Prevalence of Abdominal Aortic Aneurysms: A Systematic Review and Modeling Analysis

OBJECTIVE

To estimate the global and regional prevalence and cases of abdominal aortic aneurysms (AAAs) in 2019 and to evaluate major associated factors.

BACKGROUND

Understanding the global prevalence of AAA is essential for optimizing health services and reducing mortality from reputed AAA.

METHODS

PubMed, MEDLINE, and Embase were searched for articles published until October 11, 2021. Population-based studies that reported AAA prevalence in the general population, defined AAA as an aortic diameter of 30 mm or greater with ultrasonography or computed tomography. A multilevel mixed-effects meta-regression approach was used to establish the relation between age and AAA prevalence for high-demographic sociodemographic index and low-and middle-sociodemographic index countries. Odds ratios of AAA associated factors were pooled using a random-effects method.

RESULTS

We retained 54 articles across 19 countries. The global prevalence of AAA among persons aged 30 to 79 years was 0.92% (95% CI, 0.65-1.30), translating to a total of 35.12 million (95% CI, 24.94-49.80) AAA cases in 2019. Smoking, male sex, family history of AAA, advanced age, hypertension, hypercholesterolemia, obesity, cardiovascular disease, cerebrovascular disease, claudication, peripheral artery disease, pulmonary disease, and renal disease were associated with AAA. In 2019, the Western Pacific region had the highest AAA prevalence at 1.31% (95% CI, 0.94-1.85), whereas the African region had the lowest prevalence at 0.33% (95% CI, 0.23-0.48).

CONCLUSIONS

A substantial proportion of people are affected by AAA. There is a need to optimize epidemiological studies to promptly respond to at-risk and identified cases to improve outcomes.

Abdominal Aortic Aneurysm Detection in Bioelectrical Impedance Cardiovascular Screenings-A Pilot Study

Screening and diagnosing abdominal aortic aneurysms (AAA) are currently dependent on imaging studies such as ultrasound or computed tomography angiography. All imaging studies offer distinct advantages but also suffer from inherent limitations such as examiner dependency or ionizing radiation. Bioelectrical impedance analysis has previously been investigated with respect to its use in the detection of several cardiovascular and renal pathologies. The present pilot study assessed the feasibility of AAA detection based on bioimpedance analysis. In this single-center exploratory pilot study, measurements were conducted among three different cohorts: patients with AAA, end-stage renal disease patients without AAA, and healthy controls. The device used in the study, CombynECG, is an open-market accessible device for segmental bioelectrical impedance analysis. The data was preprocessed and used to train four different machine learning models on a randomized training sample (80% of the full dataset). Each model was then evaluated on a test set (20% of the full dataset). The total sample included 22 patients with AAA, 16 chronic kidney disease patients, and 23 healthy controls. All four models showed strong predictive performance in the test partitions. Specificity ranged from 71.4 to 100%, while sensitivity ranged from 66.7 to 100%. The best-performing model had 100% accuracy for classification when applied to the test sample. Additionally, an exploratory analysis to approximate the maximum AAA diameter was conducted. An association analysis revealed several impedance parameters that might possess predictive ability with respect to aneurysm size. AAA detection via bioelectrical impedance analysis is technically feasible and appears to be a promising technology for large-scale clinical studies and routine clinical screening assessments.

The Challenge of Endoleaks in Endovascular Aneurysm Repair (EVAR): A Review of Their Types and Management

An abdominal aortic aneurysm (AAA) is a dilatation of the abdominal aorta above 3 cm or 50% greater than the segment above. It is a dangerous condition accounting for a substantial number of deaths per year and increasing at an alarming rate. Various factors come into play in the development of AAAs, which this study has elaborated on, including smoking and old age, demographics, and comorbid conditions. Endovascular aneurysm repair (EVAR) is a newer treatment modality used for AAAs in which an endograft device is placed into the aorta, thereby creating a bypass tract from the aneurysm and generating flow mimicking that of the natural aorta. It is minimally invasive and associated with less postoperative mortality and reduced hospital stay. However, EVAR is also associated with significant postoperative complications, including endoleaks, which were reviewed in depth. Endoleaks are postprocedural leaks into the aneurysm sac that are usually identified immediately after graft placement and indicate treatment failure. They are of five subtypes, categorized according to their mechanism of development. The most common type is type II endoleaks, and the most dangerous is type I endoleaks. Each subtype has multiple management options with varying rates of success. Prompt identification along with appropriate treatment of endoleaks can lead to better postoperative outcomes and improved quality of life for patients.

Contrast-enhanced CT radiomics improves the prediction of abdominal aortic aneurysm progression

OBJECTIVES

To determine if three-dimensional (3D) radiomic features of contrast-enhanced CT (CECT) images improve prediction of rapid abdominal aortic aneurysm (AAA) growth.

METHODS

This longitudinal cohort study retrospectively analyzed 195 consecutive patients (mean age, 72.4 years ± 9.1) with a baseline CECT and a subsequent CT or MR at least 6 months later. 3D radiomic features were measured for 3 regions of the AAA, viz. the vessel lumen only; the intraluminal thrombus (ILT) and aortic wall only; and the entire AAA sac (lumen, ILT, and wall). Multiple machine learning (ML) models to predict rapid growth, defined as the upper tercile of observed growth (> 0.25 cm/year), were developed using data from 60% of the patients. Diagnostic accuracy was evaluated using the area under the receiver operating characteristic curve (AUC) in the remaining 40% of patients.

RESULTS

The median AAA maximum diameter was 3.9 cm (interquartile range [IQR], 3.3-4.4 cm) at baseline and 4.4 cm (IQR, 3.7-5.4 cm) at the mean follow-up time of 3.2 ± 2.4 years (range, 0.5-9 years). A logistic regression model using 7 radiomic features of the ILT and wall had the highest AUC (0.83; 95% confidence interval [CI], 0.73-0.88) in the development cohort. In the independent test cohort, this model had a statistically significantly higher AUC than a model including maximum diameter, AAA volume, and relevant clinical factors (AUC = 0.78, 95% CI, 0.67-0.87 vs AUC = 0.69, 95% CI, 0.57-0.79; p = 0.04).

CONCLUSION

A radiomics-based method focused on the ILT and wall improved prediction of rapid AAA growth from CECT imaging.

KEY POINTS

• Radiomic analysis of 195 abdominal CECT revealed that an ML-based model that included textural features of intraluminal thrombus (if present) and aortic wall improved prediction of rapid AAA progression compared to maximum diameter. • Predictive accuracy was higher when radiomic features were obtained from the thrombus and wall as opposed to the entire AAA sac (including lumen), or the lumen alone. • Logistic regression of selected radiomic features yielded similar accuracy to predict rapid AAA progression as random forests or support vector machines.