Large Abdominal Aortic Aneurysm Research Articles

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

ObjectiveThe United States Preventative Services Task Force guidelines for screening for abdominal aortic aneurysms (AAA) are broad and exclude many at risk groups. We analyzed a large AAA screening database to examine the utility of a novel machine learning (ML) model for predicting individual risk of AAA. MethodsWe created a ML model to predict the presence of AAAs (>3 cm) from the database of a national nonprofit screening organization (AAAneurysm Outreach). Participants self-reported demographics and comorbidities. The model is a two-layered feed-forward shallow network. The ML model then generated AAA probability based on patient characteristics. We evaluated graphs to determine significant factors, and then compared those graphs with a traditional logistic regression model. ResultsWe analyzed a cohort of 10,033 patients with an AAA prevalence of 2.74%. Consistent with logistic regression analysis, the ML model identified the following predictors of AAA: Caucasian race, male gender, advancing age, and recent or past smoker with recent smoker having a more profound affect (P < .05). Interestingly, the ML model showed body mass index (BMI) was associated with likelihood of AAAs, especially for younger females. The ML model also identified a higher than predicted risk of AAA in several groups, including female nonsmokers with cardiac disease, female diabetics, those with a family history of AAA, and those with hypertension or hyperlipidemia at older ages. An elevated BMI conveyed a higher than expected risk in male smokers and all females. The ML model also identified a complex relationship of both diabetes mellitus and hyperlipidemia with gender. Family history of AAA was a more important risk factor in the ML model for both men and women too. ConclusionsWe successfully developed an ML model based on an AAA screening database that unveils a complex relationship between AAA prevalence and many risk factors, including BMI. The model also highlights the need to expand AAA screening efforts in women. Using ML models in the clinical setting has the potential to deliver precise, individualized screening recommendations.

Morphology of Abdominal Aortic Aneurysms and Correlation with Biomechanical Tests of Aneurysmal Wall Fragments

Evaluate how specific morphologic aspects of abdominal aortic aneurysms (AAAs), including asymmetries, curvatures, tortuosities, and angulations, among others can influence the intrinsic biomechanical properties of the AAA's wall. This study analyzed the correlation of geometric measurements (1-dimensional, 2-dimensional, and 3-dimensional) of preoperative tomographic images of AAA with uniaxial biomechanical tests of the arterial wall fragments of these AAA obtained in open surgical repair of aneurysms. It was a multicenter, experimental, and observational study, and initially 54 individuals were selected who underwent open surgical of AAA, with valid biomechanical tests of the anterior wall of the AAA. Seven individuals were excluded because they had poor preoperative quality computed tomography scans and/or artifacts that impeded image segmentation and extraction of AAA geometric indices. The aortic fragments were subjected to uniaxial biomechanical destructive tests to obtain the following data: maximum load, failure stress, failure tension, failure strain energy, strain, and fragment thickness. In the same patients, preoperative computed tomography scans were performed with the extraction of 26 geometric indices, subdivided into 9 1-dimensional indices, 6 2-dimensional indices, and 11 3-dimensional indices. Data were subjected to statistical analysis using SPSS version28. Comparing ruptured and unruptured AAA, no statistical difference was observed between the biomechanical and geometric parameters. The fragment thickness of the ruptured AAA was lower than that of the unruptured AAA (P<0.05). By comparing tomographic geometric indices and biomechanical parameters of the aortic fragments using Pearson's coefficient, positive and linear correlations (P<0.05) were observed between the geometric variable maximum diameter (Dmax) of the AAA with maximum load (r=0.408), failure tension (r=0.372), and failure stress (r=0.360). Positive and linear correlations were also observed between the variable diameter/height ratio (DHr) and the maximum load (r=0.360), failure tension (r=0.354), and failure stress (r=0.289). The geometric variable DHr was dependent and correlated with Dmax. Simple regression analysis showed that R2 varied between 8.3% and 16.7%, and all models were significant (P<0.05). Dmax and DHr were linearly and positively correlated with the resistance parameters (maximum load, failure tension, and failure stress) of the AAA fragments. The DHr variable is dependent and correlated with Dmax. There was no correlation between the other geometric indices and the biomechanical parameters of the AAA wall. The asymmetries did not globally influence the biomechanics of AAA wall; however, they may influence regionally. Larger AAAs were stronger than smaller ones. Therefore, such findings may point toward Dmax is still the main geometric parameter, which influences the anterior wall, and possibly globally in the AAA.

Association of women-specific size threshold and mortality in elective abdominal aortic aneurysm repair.

It is unclear whether women derive mortality benefit from early repair of abdominal aortic aneurysms (AAA). The aim of this study was to compare short- and mid-term mortality for women treated at small versus large diameters. Women receiving elective repair of AAA at small (49-54 mm) and large (≥55 mm) diameters from 2008 to 2022 were extracted from the Swedish National Registry for Vascular Surgery (n = 1642 women). The effect of diameter on 90-day, 1- and 3-year mortality was studied in logistic regression and propensity score models. Age, co-morbidities, smoking and repair modality were considered as confounders. Men (n = 9047) were analysed in parallel. Some 1642 women were analysed, of whom 34% underwent repair at small diameters (versus 52% of men). Women with small (versus large) AAAs were younger (73 versus 75 years, P < 0.001), and 63% of women in both size groups had endovascular repairs (P = 0.120). Mortality was 3.5% (90 days), 7.1% (1 year) and 15.8% (3 years), with no differences between the size strata. There was no consistent association between AAA size and mortality in multivariable models. Sex differences in mortality were almost entirely due to mortality in younger-than-average women versus men (3-year mortality: small AAAs 11.1% versus 7.3%, P < 0.030, or large 14.4% versus 10.7%, P < 0.038). Mortality in women is high and unaffected by AAA size at repair. The optimal threshold for women remains undefined. The higher rupture risk in women should not automatically translate into a lower, women-specific threshold.

Next-Generation Sequencing of microRNAs in Small Abdominal Aortic Aneurysms: MiR-24 as a Biomarker

Small abdominal aortic aneurysms (AAAs) are asymptomatic but can potentially lead to rupture if left undetected. To date, there is a lack of simple nonradiologic routine tests available for diagnosing AAAs. MicroRNAs (miRNAs) have been proven to be good-quality biomarkers in several diseases, including AAA. An attempt to identify a panel of circulating miRNAs with differential expression in AAAs via next-generation sequencing (NGS) was performed in serum samples: small AAAs (n=3), large AAAs (n=3), and controls (n=3). For miR-24, validation with real-time polymerase chain reaction (PCR) was undertaken in a larger group (n=80). In the NGS study, 23 miRNAs were identified as differentially expressed (with statistical significance) in small AAAs in comparison with controls. Among them, miR-24 showed the largest upregulation with 23-fold change (log2FC 4.5, P=0.024). For large AAAs compared with controls, and small AAAs compared with large AAAs, a panel of 33 and 131 miRNAs showed statistically significant differential expression, respectively. Based on the results of the NGS stage, a literature search was performed, and information regarding AAA pathogenesis, coronary artery disease, and peripheral arterial disease was documented where applicable: miR-24, miR-103, miR-193a, miR-486, miR-582, and miR-3663. Of these 6 miRNAs, miR-24 was chosen for further validation with real-time PCR. Additionally, in the NGS study analysis, 17 miRNAs were common between the small-large AAAs, small AAAs-controls, and large AAAs-controls comparisons: miR-7846, miR-3195, miR-486-2, miR-3194, miR-5589, miR-1538, miR-3178, miR-4771-1, miR-5695, miR-6504, miR-1908, miR-6823, miR-3159, miR-23a, miR-7853, miR-496, and miR-193a. Interestingly, in the validation stage with real-time PCR, miR-24 was found downregulated in small and large AAAs compared with controls (fold-changes: 0.27, P=0.015 and 0.15, P=0.005, respectively). No correlation was found between average Ct values, aneurysm diameter, and patients' age. Our findings further highlight the importance of miR-24 as a potential biomarker as well as a therapeutic target for abdominal aneurysmal disease. Future research and validation of a panel of miRNAs for AAA would aid in diagnosis and discrimination between diseases with overlapping pathogeneses.

Systematic Review and Meta-Analysis of the Incidence of Rupture, Repair, and Death of Small and Large Abdominal Aortic Aneurysms under Surveillance.

The ultimate goal of treating patients with abdominal aortic aneurysms (AAAs) is to repair them when the risk of rupture exceeds the risk of repair. Small AAAs demonstrate a low rupture risk, and recently, large AAAs just above the threshold (5.5-6.0 cm) seem to be at low risk of rupture as well. The present review aims to investigate the outcomes of AAAs under surveillance through a comprehensive systematic review and meta-analysis. PubMed, Embase, and the Cochrane Central Register were searched (22 March 2022; PROSPERO; #CRD42022316094). The Cochrane and PRISMA statements were respected. Blinded systematic screening of the literature, data extraction, and quality assessment were performed by two authors. Conflicts were resolved by a third author. The meta-analysis of prevalence provided estimated proportions, 95% confidence intervals, and measures of heterogeneity (I2). Based on I2, the heterogeneity might be negligible (0-40%), moderate (30-60%), substantial (50-90%), and considerable (75-100%). The primary outcome was the incidence of AAA rupture. Secondary outcomes included the rate of small AAAs reaching the threshold for repair, aortic-related mortality, and all-cause mortality. Fourteen publications (25,040 patients) were included in the analysis. The outcome rates of the small AAA group (<55 mm) were 0.3% (95% CI 0.0-1.0; I2 = 76.4%) of rupture, 0.6% (95% CI 0.0-1.9; I2 = 87.2%) of aortic-related mortality, and 9.6% (95% CI 2.2-21.1; I2 = 99.0%) of all-cause mortality. During surveillance, 21.4% (95% CI 9.0-37.2; I2 = 99.0%) of the initially small AAAs reached the threshold for repair. The outcome rates of the large AAA group (>55 mm) were 25.7% (95% CI 18.0-34.3; I2 = 72.0%) of rupture, 22.1% (95% CI 16.5-28.3; I2 = 25.0%) of aortic-related mortality, and 61.8% (95% CI 47.0-75.6; I2 = 89.1%) of all-cause mortality. The sensitivity analysis demonstrated a higher rupture rate in studies including <662 subjects, patients with a mean age > 72 years, >17% of female patients, and >44% of current smokers. The rarity of rupture and aortic-related mortality in small AAAs supports the current conservative management of small AAAs. Surveillance seems indicated, as one-fifth reached the threshold for repair. Large aneurysms had a high incidence of rupture and aortic-related mortality. However, these data seem biased by the sparse and heterogeneous literature overrepresented by patients unfit for surgery. Specific rupture risk stratified by age, gender, and fit-for-surgery patients with large AAAs needs to be further investigated.

Intermediate pressure-normalized principal wall strain values are associated with increased abdominal aortic aneurysmal growth rates.

Current abdominal aortic aneurysm (AAA) assessment relies on analysis of AAA diameter and growth rate. However, evidence demonstrates that AAA pathology varies among patients and morphometric analysis alone is insufficient to precisely predict individual rupture risk. Biomechanical parameters, such as pressure-normalized AAA principal wall strain (/PP, %/mmHg), can provide useful information for AAA assessment. Therefore, this study utilized a previously validated ultrasound elastography (USE) technique to correlate /PP with the current AAA assessment methods of maximal diameter and growth rate. Our USE algorithm utilizes a finite element mesh, overlaid a 2D cross-sectional view of the user-defined AAA wall, at the location of maximum diameter, to track two-dimensional, frame-to-frame displacements over a full cardiac cycle, using a custom image registration algorithm to produce /PP. This metric was compared between patients with healthy aortas and AAAs (≥3 cm) and compared between small and large AAAs (≥5 cm). AAAs were then separated into terciles based on /PP values to further assess differences in our metric across maximal diameter and prospective growth rate. Non-parametric tests of hypotheses were used to assess statistical significance as appropriate. USE analysis was conducted on 129 patients, 16 healthy aortas and 113 AAAs, of which 86 were classified as small AAAs and 27 as large. Non-aneurysmal aortas showed higher /PP compared to AAAs (0.044 ± 0.015 vs. 0.034 ± 0.017%/mmHg, p = 0.01) indicating AAA walls to be stiffer. Small and large AAAs showed no difference in /PP. When divided into terciles based on /PP cutoffs of 0.0251 and 0.038%/mmHg, there was no difference in AAA diameter. There was a statistically significant difference in prospective growth rate between the intermediate tercile and the outer two terciles (1.46 ± 2.48 vs. 3.59 ± 3.83 vs. 1.78 ± 1.64 mm/yr, p = 0.014). There was no correlation between AAA diameter and /PP, indicating biomechanical markers of AAA pathology are likely independent of diameter. AAAs in the intermediate tercile of /PP values were found to have nearly double the growth rates than the highest or lowest tercile, indicating an intermediate range of /PP values for which patients are at risk for increased AAA expansion, likely necessitating more frequent imaging follow-up.

Systematic review of the results of fenestrated endovascular aortic repair in octogenarians.

With the increasing life expectancy of Western populations, more octogenarians are presenting with large abdominal aortic aneurysm (AAA). Endovascular repair offers a less invasive alternative and older patients who may not have been offered open repair in the past are now being considered for elective repair with this approach. Age in isolation may not be the only consideration in recommending elective aneurysm repair. We aimed to review the literature on complex endovascular AAA repairs (mainly fenestrated endovascular aortic repair [FEVAR]) in octogenarians. A literature search was conducted using the Ovid Medline®, Embase® and Cochrane Library databases for articles published up to January 2022. All English language publications from 1995 onwards were eligible for inclusion. Search terms included: "FEVAR", "F-EVAR", "fenestrated EVAR", "fenestrated endovascular aortic repair", "fenestrated endovascular aneurysm repair", "fenestrated AAA repair", "fenestrated endograft", "fenestrated stent graft", "fenestrated", "endograft", "EVAR", "octogenarian", "elderly", "above 80" and "over 80". The literature search identified 134 potential articles. Following qualitative assessment by two independent appraisers, this was refined to 11 studies, in accordance with the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) statement. The primary outcome measure was 30-day mortality, which was highly variable, ranging from 0% to 9% in octogenarians and from 0% to 5% in non-octogenarians. However, these differences were only found to be statistically significant in two studies. The secondary outcome measures included technical success rates, major adverse events, reintervention rates, freedom from reintervention, target vessel patency, freedom from target branch instability, and length of hospital and intensive care unit stay. No statistically significant differences were found between octogenarians and non-octogenarians. Long-term survival was significantly lower for octogenarians in two studies. The perioperative outcomes of FEVAR in octogenarians are comparable with those of younger patients. FEVAR therefore appears to be an acceptable option for complex endovascular aneurysm repairs in carefully selected octogenarians. Nevertheless, this review highlights the paucity of published data on the outcomes of endovascular repair of complex aneurysms in octogenarians.

Intermediate Pressure-Normalized Strain Values Are Associated With Increased Abdominal Aortic Aneurysmal Growth Rates

Current abdominal aortic aneurysm (AAA) assessment methods rely on simple morphometric analysis of the AAA diameter and growth rate. However, evidence has shown that AAA pathology varies among patients, and morphometric analysis alone is insufficient to predict individual risk of growth. Biomechanical parameters, such as pressure-normalized aortic wall strain (εp+/PP), can provide a surrogate to vessel wall stiffness. We aimed to use our novel ultrasound elastography (USE) technique to measure ερ+/PP and correlate ερ+/PP with maximal AAA diameter and growth rate in the largest clinical trial to date. Our USE algorithm uses a finite element mesh overlayed on a 2D axial view of the user-defined AAA wall at the point of maximum diameter to track frame-to-frame displacements over a full cardiac cycle to measure ερ+/PP. ερ+/PP and growth rate were assessed between small and large AAAs based on a diameter of ≥5 cm. Patients with AAA were then separated into terciles based on ερ+/PP values of 0.0251 and 0.038 to assess differences in the AAA diameter and growth rate. Mann-Whitney U and Kruskal-Wallis tests were used to assess differences as appropriate. USE analysis was conducted on 127 patients, 16 normal aortas and 111 AAAs. A total of 79 patients had at least one follow-up clinical scan used to calculate growth rate. Of the 111 aortas, 85 were classified as small and 26 as large. AAAs showed lower ερ+/PP (stiffer) compared with nonaneurysmal aortas (0.034 ± 0.017 vs 0.044 ± 0.015 %/kPa; P = .006). There was no difference in ερ+/PP or growth rate between small and large AAAs. When divided into terciles based on ερ+/PP, there was no difference in the AAA diameter. There was a statistically significant difference in growth rate between the intermediate tercile and the outer terciles (1.46 ± 2.48 vs 3.59 ± 3.83 vs 1.78 ± 1.64 mm/y; P = .014) (Fig). Our validated USE algorithm shows that AAAs are stiffer than nonaneurysmal aortas, similar to previous reports. There was no correlation between AAA diameter and ερ+/PP, indicating that AAA stiffness is independent of diameter, and diameter thresholds alone may not accurately assess future risk of growth. AAAs in the intermediate tercile of ερ+/PP values were found to have greater growth rates than the outer tercile, indicating that an intermediate range of ερ+/PP values, regardless of diameter, place patients at increased risk for AAA growth. These findings also suggest that AAA growth may be related to a failure of collagen remodeling and may be the underlying event that leads to AAA rupture.

Women with large intact abdominal aortic aneurysms remain untreated

ObjectiveA lower elective repair rate among women with abdominal aortic aneurysms (AAAs) has been a consistent finding. Reasons behind this gender gap have not been thoroughly outlined. MethodsThis was a retrospective multicenter cohort study (ClinicalTrials.gov: NCT05346289) at three European vascular centers in Sweden, Austria and Norway. Patients in surveillance with AAAs were consecutively identified starting from January 1, 2014, until reaching a total sample size of 200 women and 200 men. All individuals were followed for 7 years through medical records. Final treatment distributions and the proportion of “truly untreated” (surgically untreated despite reaching guideline-directed thresholds: 50 mm for women and 55 mm for men) were determined. In a complementary analysis, a universal 55-mm threshold was used. Gender-specific primary reasons behind untreated statuses were clarified. Eligibility for endovascular repair among the truly untreated was assessed in a structured computed tomography analysis. ResultsWomen and men had similar median diameters at inclusion (46 mm; P = .54) and at treatment decisions (55 mm; P = .36). After 7 years, the repair rate was lower among women (47% vs 57%). More women were truly untreated (26% vs 8%; P < .001) despite similar mean ages as for male counterparts (79.3 years; P = .16). With the 55-mm threshold, 16% women still classified as truly untreated. Similar reasons for nonintervention were captured for women and men (50% due to comorbidities alone, 36% morphology and comorbidity). The endovascular repair imaging analysis revealed no gender differences. Among truly untreated women, ruptures were common (18%), and mortality was high (86%). ConclusionsSurgical AAA management differed between women and men. Women could be underserved in terms of elective repairs: one in every four women was untreated with over-the-threshold AAAs. The lack of obvious gender differences in eligibility analyses could imply unmeasured discrepancies (eg, in disease extent or patient frailty).

Transrenal Endovascular Aneurysm Repair–A Novel Approach for Abdominal Aortic Aneurysms with Difficult Neck Anatomy

The endovascular approach to treating ruptured or symptomatic abdominal aortic aneurysms (AAA) with difficult neck anatomy still poses a major challenge. This study proposes and evaluates the outcomes of a novel technique, Transrenal Endovascular Aneurysm Repair (Tr-EVAR) which utilizes the top ring 'valley' and 'peak' configuration of the Anaconda stent graft to achieve proximal seal in AAAs with an unfavourable neck. All patients treated with Tr-EVAR over a period of 10 years were identified retrospectively. Demographic, clinical and outcome data were collected, and survival analysis was performed. The time-to-event was analysed using Kaplan-Meier curves for complication-free survival, reintervention-free survival, and overall survival. During the study period, 36 patients ruptured, symptomatic or large AAAs having unfavourable necks and not fit for open repair underwent Tr-EVAR. Two patients died in the first 30 days post-procedure (5.6%). The overall survival at 1 year, 3 years and 5 years were 86%, 72% and 54% respectively with a mean overall survival of 74.0 months (SE 7.8, 95% CI 58.7 - 89.3) which was comparable to chimney EVAR. The complication-free survival and reintervention-free survival at 1 year, 3 years,5 years were 75%, 61%, 42% and 78%, 64%, 45% respectively. Tr-EVAR can be considered as an off-the-shelf solution for urgent cases not fit for open repair with unfavourable neck features for standard EVAR. Careful patient selection and planning have generated acceptable immediate, mid-and long-term results comparable to those presented by chimney EVAR in the literature.

High prevalence of abdominal aortic aneurysm in older men with cerebrovascular disease: Evaluation of a local screening program.

Patients with cerebrovascular disease may suffer from other vascular morbidities, such as abdominal aortic aneurysm (AAA). Previously, a high prevalence of AAA has been demonstrated in men 60 years of age and older who have experienced TIA or stroke. This report evaluates the results of a decade's operation of a local screening program for AAA in this selected neurologic population. Men aged ≥60 years and admitted to the neurology ward of a community-based hospital in the Netherlands from 2006 to 2017 with a diagnosis of TIA or stroke were selected for screening. The diameter of the abdominal aorta was assessed by abdominal ultrasonography. Patients with detected AAA were referred for evaluation by a vascular surgeon. AAA was detected in 72 of 1,035 screened patients (6.9%). AAAs with a diameter of 3.0-3.9 cm accounted for 61.1% of the total aneurysms found; AAAs with a diameter of 4.0-5.4 cm accounted for 20.8% of the total; and large aneurysms with a diameter of ≥5.5 cm accounted for 18.1% of all aneurysms discovered. A total of 18 patients (1.7%) underwent elective aneurysm repair. The detection rate of AAA in older men with cerebrovascular disease was roughly 5-fold the detection rate in known European screening programs in older men from the general population. The proportion of large AAAs (≥5.5 cm) was also substantially higher. These findings reveal a previously unknown co-morbidity in patients with cerebrovascular disease and may be helpful for cardiovascular management of this large group of neurologic patients. Current and future AAA screening programs may also benefit from this knowledge.

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

Controversy persists regarding the optimal treatment for large abdominal aortic aneurysm (AAA), highlighted by the publication of the National Institute for Health and Care Excellence (NICE) guideline (NG156) on March 2020. The pendulum of opinion swings once more from endovascular to open surgical treatment. We report our experience over the last 15years in treating consecutive AAA by open surgery. A retrospective review of a prospectively collected vascular database of all patients undergoing infra-renal open abdominal aortic aneurysm repair (OR) repair from 2004 to 2019 at the largest aneurysm centre in the United Kingdom. OR for elective and emergency (ruptured and symptomatic) outcomes included early morbidity and 30-day mortality, and long-term survival. 1017 patients underwent OR between 2004-2019, on application of our inclusion-criteria 994 patients formed our cohort for analysis (81.2% male) with a mean age 73.6 ± 7.8years treated by OR for AAA. In that group 672 were elective and 308 were emergency (for ruptured or symptomatic). Overall 30day mortality was 11.3%, elective 30day mortality was 2.5%, and emergency 30day mortality was 29.9%. 30day re-intervention rate was 9.5%, (elective 7.0%, emergency 15.9%). Survival at 1000days for elective repair was 72 v 46.7% for emergency and at 2000 days was 43.4% for elective v 25% for emergency. Our data confirm that open surgery for AAA can be performed in large volume centres quite safely. Elective and Emergency surgery does affect early 30day mortality but does not influence long-term outcome.

Outcomes of embolization procedures for type II endoleaks following endovascular abdominal aortic repair.

The objective of this study was to investigate the mid-term outcomes of embolization procedures for type II endoleak after endovascular abdominal aortic repair, and clarify the risk factors for aneurysm enlargement after embolization procedures. This was a retrospective multicenter registry study enrolling patients who underwent embolization procedures for type II endoleaks after EVAR from January 2012 to December 2018 at 19 Japanese centers. The primary end point was the rate of freedom from aneurysm enlargement, more than 5mm in the aortic maximum diameter, after an embolization procedure. Demographic, procedural, follow-up, and laboratory data were collected. Continuous variables were summarized descriptively, and Kaplan-Meier analyses and a Cox regression model were used for statistical analyses. A total of 315 patients (248 men and 67 women) were enrolled. The average duration from the initial embolization procedure to the last follow-up was 31.6± 24.6months. The rates of freedom from aneurysm enlargement at 3 and 5years were 55.4± 3.8% and 37.0± 5.2%, respectively. A multivariate analysis revealed that a larger aortic diameter at the initial embolization procedure and the presence of a Moyamoya endoleak, defined as heterogeneous contrast opacity with an indistinct faint border, were associated with aneurysm enlargement after embolization management. The embolization procedures were generally ineffective in preventing further expansion of abdominal aortic aneurysms in patients with type II endoleaks after EVAR, especially in patients with a large abdominal aortic aneurysm and/or a presence of a Moyamoya endoleak.

Gender-specific Predicted Normal Aortic Size and Its Consequences of the Population-Based Prevalence of Abdominal Aortic Aneurysms

To investigate if a relative-size-index of the abdominal aortic diameter influences the prevalence estimates of abdominal aortic dilatations compared to absolute diameters. Cross-sectional study. Participants from the Viborg Vascular Screening Trial, Viborg Women Cohort, and the Viborg Screening Program. Through multivariate linear regression analyses, two gender-specific prediction-equations were developed based upon body-surface area and age. The definitions of absolute and relative size of aortic ectasies were 25-29 mm and 1.25-1.49 x individual-predicted size (IPS), abdominal aortic aneurysm (AAA) 30 mm and 1.5 x IPS, and large repair-recommendable AAA ≥55mm or ≥ 2.75 x IPS, respectively. 19 269 males (69.6 years) and 2 426 females (67.1 years) attended the population- and ultrasound-based screening studies for AAA. The mean peak systolic abdominal anterior-posterior inner to inner diameter was 19.1mm (±5.3mm) and 16.6mm (±2.8mm) (P< .001) in males and females, respectively. Body surface area showed the strongest correlation with aortic diameters in both males (r=0.19, p< .001) and females (r=0.17, p< .001). Age correlated significantly with size, but only in males (r=0.03, p< .001). The prevalence in men of absolute-size-defined and relative-size-index-defined screening-detected aortic ectasies, AAAs and repair-recommendable AAAs were: 5.9% and 9.5% (p< .001), 3.3% and 4.2% (p< .001) and 9.9% and 15.2% (p= .004), respectively. Prevalence in females of absolute-size-defined and relative-size-index-defined screening-detected aortic ectasies, AAAs and repair-recommendable AAAs were 1.2% and 5.8% (p< .001), 0.5% and 1.3% (p= .003) and 0.0% and 23.1% (p= .553), respectively. Despite statistical differences, ultrasound-based absolute diameters to detect AAA seem acceptable in men. In females, poor agreements were noticed concerning all three categories of aneurysms, indicating that the current absolute diagnostic cut-points do not reflect female anatomy.

Man With Cardiac Arrest

A 71-year-old man described abdominal pain prior to an out-of-hospital cardiac arrest with an initial pulseless rhythm. During emergency department (ED) resuscitation, a bedside ultrasound confirmed a large abdominal aortic aneurysm surrounded by a hematoma. We initiated blood transfusion and performed ultrasound-guided resuscitative endovascular balloon occlusion of the aorta (REBOA) within 30 minutes after ED arrival. During resuscitation, a transesophageal echocardiogram established the REBOA location (Video 1, Figure 1), revealing hyperechoic blood below the REBOA balloon.

Abstract 12986: Internal Iliac Artery Occlusion With the Amplatzer Vascular Plug During Endovascular Repair of Large Abdominal Aortic Aneurysm

Background: Retrograde blood flow from the internal iliac artery resulting in a type II endoleak is a challenging complication of endovascular aorto-iliac aneurysm repair. Several methods have been developed to address this concern. We present a case where the Amplatzer vascular plug was used to embolize the internal iliac artery in a patient undergoing aorto-iliac stent-grafting with extension of the graft into the external iliac artery. Case: A 67-year-old male presented with abdominal pain. Abdominal contrast computed tomography confirmed a large infrarenal abdominal aortic aneurysm (AAA) measuring 100 mm across, extending into the common iliac artery on the right and the external iliac artery on the left, with perianeurysmal fat stranding indicating impending rupture. The patient was taken emergently to the operating room. Vascular access was obtained through bilateral common femoral arteries. The left internal iliac was occluded with an Amplatzer 16 mm by 12 mm vascular plug, with excellent angiographic apposition. A bifurcated aorto-iliac graft was then sequentially deployed to repair the aneurysm. Final angiography showed patent renal arteries with no endoleak. The patient was discharged home the following day. Discussion: Embolization of the internal iliac artery is indicated in endovascular aorto-iliac aneurysm repair to prevent endoleak formation. Traditionally performed with coils, the Amplatzer vascular plug has emerged as a safe and effective alternative, with the added advantage of recoverability prior to definitive release. Conclusion: Endovascular repair of an AAA must consider the complication of endoleak formation. In this case, the use of an Amplatzer vascular plug was successful in preventing a type II endoleak from the internal iliac artery. Panel A. 3D reconstruction of aneurysm anatomy; Panel B. Angiogram showing final result of endovascular repair with successful occlusion of the left internal iliac artery

A SENSE OF IMPENDING DOOM: MASSIVE AORTIC ABDOMINAL ANEURYSM PRESENTING AS SUBACUTE BACK PAIN

A SENSE OF IMPENDING DOOM: MASSIVE AORTIC ABDOMINAL ANEURYSM PRESENTING AS SUBACUTE BACK PAIN

Single-Cell Sequencing Analysis and Multiple Machine Learning Methods Identified G0S2 and HPSE as Novel Biomarkers for Abdominal Aortic Aneurysm.

Identifying biomarkers for abdominal aortic aneurysms (AAA) is key to understanding their pathogenesis, developing novel targeted therapeutics, and possibly improving patients outcomes and risk of rupture. Here, we identified AAA biomarkers from public databases using single-cell RNA-sequencing, weighted co-expression network (WGCNA), and differential expression analyses. Additionally, we used the multiple machine learning methods to identify biomarkers that differentiated large AAA from small AAA. Biomarkers were validated using GEO datasets. CIBERSORT was used to assess immune cell infiltration into AAA tissues and investigate the relationship between biomarkers and infiltrating immune cells. Therefore, 288 differentially expressed genes (DEGs) were screened for AAA and normal samples. The identified DEGs were mostly related to inflammatory responses, lipids, and atherosclerosis. For the large and small AAA samples, 17 DEGs, mostly related to necroptosis, were screened. As biomarkers for AAA, G0/G1 switch 2 (G0S2) (Area under the curve [AUC] = 0.861, 0.875, and 0.911, in GSE57691, GSE47472, and GSE7284, respectively) and for large AAA, heparinase (HPSE) (AUC = 0.669 and 0.754, in GSE57691 and GSE98278, respectively) were identified and further verified by qRT-PCR. Immune cell infiltration analysis revealed that the AAA process may be mediated by T follicular helper (Tfh) cells and the large AAA process may also be mediated by Tfh cells, M1, and M2 macrophages. Additionally, G0S2 expression was associated with neutrophils, activated and resting mast cells, M0 and M1 macrophages, regulatory T cells (Tregs), resting dendritic cells, and resting CD4 memory T cells. Moreover, HPSE expression was associated with M0 and M1 macrophages, activated and resting mast cells, Tregs, and resting CD4 memory T cells. Additional, G0S2 may be an effective diagnostic biomarker for AAA, whereas HPSE may be used to confer risk of rupture in large AAAs. Immune cells play a role in the onset and progression of AAA, which may improve its diagnosis and treatment.

Large abdominal aortic aneurysm presented with concomitant acute lumbar disc herniation – a case report

The purpose of this case report was to describe chiropractic management of acute lumbar disc herniation in a patient with a large abdominal aortic aneurysm. A 72-year-old male patient presented with low back pain and right lower leg numbness for 12 months. A review of full-spine X-ray and lumbar MRI revealed moderate spondylosis at L2-5, moderate lumbar scoliosis, and a 7.15 cm abdominal aortic aneurysm (AAA). Given the minimum 2-weeks of referral waiting time to receive treatment for AAA, the patient received chiropractic treatment with a hybrid rehabilitation to address the disc herniation causing severe physical disability. Through the treatments, the patient's pain was significantly alleviated with careful consideration of potential risk factors associated with AAA. In addition, the acute disc herniation was successfully managed by a series of chiropractic treatments before and after the operation for AAA. This case supports that low back pain in patients with AAA can be managed by manual therapy, in contrast to a widespread belief that manual therapy is contraindicated in AAA. More case reports of AAA patients with low back pain are warranted to assess the effectiveness and safety of manual therapy along with surgical treatment for AAA.

Influencing Factors of Diabetes Mellitus on Abdominal Aortic Aneurysm Diameter and Biochemical Parameters

Objective To investigate the effect of diabetes mellitus and hypoglycemic treatment on the diameter and biochemical parameters of abdominal aortic aneurysm (AAA).Methods A case-control study was conducted to retrospectively analyze the clinical data of AAA patients in Peking Union Medical College Hospital from 2015 to 2021.The AAA patients were classified into a group with diabetes mellitus (n=53) and a group without diabetes mellitus (n=104),and the biochemical parameters and aneurysm diameter were compared between the two groups.According to the aneurysm diameter,they were further classified into a small and medium abdominal aortic aneurysm group (SMAAA group,n=85) and a large abdominal aortic aneurysm group (LAAA group,n=72),and the biochemical parameters between the two groups were compared.Results Among the 157 cases with AAA,the incidence of hypertension in the group without diabetes mellitus was higher than that in the group with diabetes mellitus (χ2=8.147,P=0.004).The aneurysm diameter,homocysteine,and D-dimer in the group with diabetes mellitus were lower than those in the group without diabetes mellitus (t=-3.148,P=0.002;U=-1.503,P=0.013;U=-3.002,P=0.003).The aneurysm diameter and D-dimer in the SMAAA group were lower than those in the LAAA group (t=-14.406,P<0.001;U=-0.388,P<0.001).Multivariate Logistic regression analysis showed that diabetes mellitus (OR=0.477,95%CI=0.238-0.955,P=0.037) and hypoglycemic treatment (OR=0.477,95%CI=0.238-0.955,P=0.037) did not increase the risk of AAA enlargement.Conclusion Diabetes mellitus and hypoglycemic therapy may affect the growth rate of AAA by lowering D-dimer and inflammatory indexes.