Maximum Abdominal Aortic Aneurysm Diameter Research Articles

Postoperative serum mir-28-5p level has predictive value for the prognosis after endovascular abdominal aortic aneurysm repair

BackgroundWe explored the clinical significance of miR-28-5p pre- and post-endovascular abdominal aortic aneurysm repair (EVAR) in abdominal aortic aneurysm (AAA) patients.MethodsSubjects included AAA patients receiving EVAR and non-AAA people without statistical differences from AAA patient in comorbidities/Framingham risk score. Fasting elbow venous blood (4 mL) was collected in the morning of the day of EVAR surgery and in the morning of 3 months post-EVAR. Pre-/post-EVAR serum miR-28-5p expression, AAA maximum diameter alterations, CD3+/CD4+/CD8+/TC/TG pre-/post-EVAR, and the correlations between miR-28-5p and AAA maximum diameter were investigated. Prediction of miR-28-5p on post-EVAR mortality, prognosis, and independent factors of post-EVAR death were analyzed using receiver operating characteristic curve (ROC)/Kaplan-Meier curve/univariable and multivariable Cox regression. According to the cut-off value of ROC curve for postoperative miR-28-5p was the cut-off value, and the patients were classified into the miR-28-5p high- and low-expression groups. The survival or death of both groups were compared after 48-month follow-up.ResultsSerum miR-28-5p levels in AAA patients dropped post-EVAR. AAA patients showed notable differences in CD3+/CD4+/CD8+/TC/TG levels pre-/post-EVAR. The miR-28-5p low-expression group exhibited higher CD3+/CD4+ and lower CD8+/TC/TG levels. We observed a positive correlation between post-EVAR miR-28-5p and AAA maximum diameter and between the pre-/post-EVAR miR-28-5p fold change and the AAA maximum diameter change. Postoperative miR-28-5p demonstrated good predictive value for postoperative death. Hypertension, Framingham risk score, TC, TG, and miR-28-5p were independent influencing factors of post-EVAR death.ConclusionEVAR decreased serum miR-28-5p expression in AAA patients. Post-operative miR-28-5p level and pre-/post-operative fold change level are positively-correlated with AAA diameter.

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

ObjectiveBiomechanical modeling of infrarenal aortic aneurysms seeks to predict ruptures in advance, thereby reducing aneurysm-related deaths. As individual methods focusing on strain and stress analysis lack adequate discretization power, this study aims to explore multifactorial characterization for progressive aneurysmal degeneration. The study’s objective is to compare stress- and strain-related parameters in infrarenal aortic aneurysms. MethodsTwenty-two patients with abdominal aortic aneurysms (AAAs) (mean maximum diameter, 53.2 ± 7.2 mm) were included in the exploratory study, examined by computed tomography angiography (CTA) and three-dimensional real-time speckle tracking ultrasound (4D-US). The conformity of aneurysm anatomy in 4D-US and CTA was determined with the mean point-to-point distance (MPPD). CTA was employed for each AAA to characterize stress-related indices using the semi-automated A4-clinics RE software. Five segmentations from one 4D-US examination were fused into one averaged model for strain analysis using MATLAB and the Abaqus solver. ResultsThe mean MPPD between the adjacent points of the 4D-US and CTA-derived geometry was 1.8 ± 0.4 mm. The interclass correlation coefficients for all raters and all measurements for the maximum AAA diameter in 2D, 4D ultrasound, and CTA indicate moderate to good reliability (interclass correlation coefficient1 0.69 with 95% confidence interval [CI], 0.49-0.84; P < .001). The peak wall stress (PWS) correlates fairly with the maximum AAA diameter in 2D-US (r = 0.54; P < .01) and 4D-US (r = 0.53; P < .05) and moderately strongly with the maximum exterior AAA diameter (r = 0.63; P < .01). The peak wall rupture risk index shows a strong correlation with the PWS (ρ > 0.9; P < .001) and is influenced by anatomical parameters with equal strength. Isolated observation of the intraluminal thrombus does not provide significant information in the determination of PWS. The maximum AAA diameter in 2D-US shows a fair negative correlation with the mean circumferential, longitudinal and in-plane shear strain (ρ = −0.46; r = −0.45; ρ = −0.47; P < .05 for all). The circumferential strain ratio as an indicator of wall motion heterogeneity increases with the aneurysm diameter (r = 0.47; P < .05). The direct comparison of wall strain and wall stress indices shows no quantitative correlation. ConclusionsThe strain and stress analyses provide independent biomechanical information of AAAs. At the current stage of development, the two methods are considered complementary and may optimize a more patient-specific rupture risk prediction in the future.

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.

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.

Early Results of Elective Endovascular Repair of Infrarenal Abdominal Aortic Aneurysms With the MinosTM Stent-Graft System.

A variety of last-generation endografts are currently available for standard endovascular repair (EVAR) of infrarenal abdominal aortic aneurysms (AAAs). The purpose of this study is to report the preliminary clinical outcomes of the Minos trimodular stent-graft system, which was recently introduced to the European market. Between February 2020 and 2022, we treated 41 consecutive AAA patients (mean age 72.2±8.5, 37 males) with elective standard EVAR using the Minos. The mean maximum diameter of AAAs was 54.7±6.6 mm, the mean proximal neck's (PN) diameter was 24.8±2.7 mm, while the relevant length and angulation were 16.0 mm and 21.7°, respectively. Overall, 22 (53.6%) patients presented with shorter and angulated PN, according to the stent-graft's instructions of use, and in 6 (14.6%) patients the PN angulation >60° was combined with concomitant iliac angulation >60°. Eleven (26.8%) EVARs were performed with concomitant enormous iliac artery narrowing and tortuosity. Finally, in 19 (46.3%) AAAs, the distal iliac landing zone was aneurysmatic and they were treated with the bell-bottom technique in 17 patients and with limb extension to the external iliac artery in two cases. We evaluated technical and clinical success of the index procedures, which was based on the combination of five factors: freedom from EVAR-related mortality, from graft-related endoleak of any type, from migration at any part of graft as well the absence of notable increase AAA's sac maximum diameter and the patency of bifurcated stent-graft and of access vessels. Primary technical and clinical success of index procedures was 100%. During a median 12-month radiological follow-up the clinical success remained 100%. No type I or III endoleak, stent-graft migration, EVAR-related death, AAA rupture, or graft-related adverse events or reinterventions were documented. Four (9.8%) type II endoleaks were detected with stable AAA sac diameter. The overall incidence of sac regression was 34.1% (n=14). The preliminary results of our series showed that Minos provided excellent feasibility and safety features even through angulated and tortuous iliac vessels and in short and angulated PNs. The overall clinical success at 1 year suggests that performance of Minos follows very high standards. Further validation of these promising results with long-term data is acquired to complete the evaluation of this recently introduced stent-graft system. The current study explored the clinical performance of a new in market ultra-low profile bifurcated abdominal aortic stent-graft, the MINOS. The early and 12-month results of study suggest that implantation of this stent-graft in standard EVAR, even in hostile proximal aortic neck and iliac vessels conditions, follows very high clinical standards and encourage the further clinical use of MINOS.

Identifying Patients at High Risk for Post-EVAR Aneurysm Sac Growth.

Post-EVAR (endovascular aneurysm repair) aneurysm sac growth can be seen as therapy failure as it is a risk factor for post-EVAR aneurysm rupture. This study sought to identify preoperative patient predictors for developing post-EVAR aneurysm sac growth. A systematic review was conducted to select potential predictive preoperative factors for post-EVAR sac growth (including a total of 34.886 patients), which were evaluated by a retrospective single-center analysis of patients undergoing EVAR between 2009 and 2019 (N=247) with pre-EVAR computed tomography scans and at least 1 year follow-up. The primary study outcome was post-EVAR abdominal aortic aneurysm (AAA) sac enlargement (≥5 mm diameter increase). Multivariate Cox regression and Kaplan-Meier survival curves were constructed. Potential correlative factors for post-EVAR sac growth included in the cohort analysis were age, sex, anticoagulants, antiplatelets, renal insufficiency, anemia, low thrombocyte count, pulmonary comorbidities, aneurysm diameter, neck diameter, neck angle, neck length, configuration of intraluminal thrombus, common iliac artery diameter, the number of patent lumbar arteries, and a patent inferior mesenteric artery. Multivariate analysis showed that infrarenal neck angulation (hazard ratio, 1.014; confidence interval (CI), 1.001-1.026; p=0.034) and the number of patent lumbar arteries (hazard ratio, 1.340; CI, 1.131-1.588; p<0.001) were associated with post-EVAR growth. Difference in estimated freedom from post-EVAR sac growth for patients with ≥4 patent lumbar arteries versus <4 patent lumbar arteries became clear after 2 years: 88.5% versus 100%, respectively (p<0.001). Of note, 31% of the patients (n=51) with ≥4 patent lumbar arteries (n=167) developed post-EVAR sac growth. In our cohort, the median maximum AAA diameter was 57 mm (interquartile range [IQR] = 54-62) and the median postoperative follow-up time was 54 months (IQR = 34-79). In all, 23% (n=57) of the patients suffered from post-EVAR growth. The median time for post-EVAR growth was 37 months (IQR = 24-63). In 46 of the 57 post-EVAR growth cases (81%), an endoleak was observed; 2.4% (n=6) of the patients suffered from post-EVAR rupture. The total mortality in the cohort was 24% (n=60); 4% (n=10) was AAA related. This study showed that having 4 or more patent lumbar arteries is an important predictive factor for postoperative sac growth in patients undergoing EVAR. This study strongly suggests that having 4 or more patent lumbar arteries should be included in preoperative counseling for EVAR, in conjunction to the instructions for use (IFU).

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

To determine if three-dimensional (3D) radiomic features of contrast-enhanced CT (CECT) images improve prediction of rapid abdominal aortic aneurysm (AAA) growth. This longitudinal cohort study retrospectively analyzed 195 consecutive patients (mean age, 72.4years ± 9.1) with a baseline CECT and a subsequent CT or MR at least 6months 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 (> 0.25cm/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. The median AAA maximum diameter was 3.9cm (interquartile range [IQR], 3.3-4.4cm) at baseline and 4.4cm (IQR, 3.7-5.4cm) at the mean follow-up time of 3.2 ± 2.4years (range, 0.5-9years). 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). A radiomics-based method focused on the ILT and wall improved prediction of rapid AAA growth from CECT imaging. • 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.

Aortobifemoral reconstruction in open abdominal aortic aneurysm repair is associated with increased morbidity and mortality

ObjectiveMuch attention has been given to the influence of anatomic and technical factors, such as maximum abdominal aortic aneurysm diameter and proximal clamp position, in open abdominal aortic aneurysm repair (OSR). However, no studies have rigorously examined the correlation between site of distal anastomosis and OSR outcomes despite conventional wisdom that more proximal sites of anastomosis are preferrable when technically feasible. This study aimed to test the association between sites of distal anastomosis and clinical outcomes for patients undergoing primary elective OSR. MethodsOur study included 5683 patients undergoing primary elective OSR at 233 centers from 2014 to 2020. Using a variety of statistical methods to account for potential confounders, including multivariable logistic regression and Cox proportional hazards modeling, as well as subgroup analysis, we examined the association between site of distal anastomosis and clinical outcomes in elective OSR. Primary outcomes were major in-hospital complication rate, 30-day mortality, and long-term survival. ResultsPatients undergoing elective aortobifemoral reconstruction (n = 672) exhibited significantly increased rates of smoking, chronic obstructive pulmonary disease, and peripheral artery disease in comparison to patients undergoing elective OSR with distal anastomosis to the aorta (n = 2298), common iliac artery (n = 2163), or external iliac artery (n = 550). Patients undergoing aorto-aortic tube grafting were significantly less likely to exhibit iliac aneurysmal disease and significantly more likely to be undergoing elective OSR with a suprarenal or supraceliac proximal clamp position. Using multivariable logistic regression and Cox proportional hazards analysis to control for important confounders, such as age, smoking status, and medical history, we found that distal anastomosis to the common femoral artery was associated with increased odds of major in-hospital complications (adjusted odds ratio, 1.79; 95% confidence interval, 1.46-2.18; P < .001) and reduced long-term survival (adjusted hazard ratio, 1.44; 95% confidence interval, 1.09-1.89; P = .010). We observed no significant differences in 30-day mortality across sites of distal anastomosis in our study population. ConclusionsIt is generally accepted that more proximal sites of distal anastomosis should be selected in OSR when technically feasible. Our findings support this hypothesis by demonstrating that distal anastomosis to the common femoral artery is associated with increased perioperative morbidity and reduced long-term survival. Careful diligence regarding optimization of preoperative health status, perioperative care, and long-term follow-up should be applied to mitigate major complications in this patient population.

A Novel Preoperative Risk Assessment Tool to Identify Patients at Risk of Contrast-Associated Acute Kidney Injury After Endovascular Abdominal Aortic Aneurysm Repair

Contrast-associated acute kidney injury (CA-AKI) after endovascular abdominal aortic aneurysm repair (EVAR) is associated with mortality and morbidity. Risk stratification remains a vital component of preoperative evaluation. We sought to generate and validate a preprocedure CA-AKI risk stratification tool for elective EVAR patients. We queried the Blue Cross Blue Shield of Michigan Cardiovascular Consortium database for elective EVAR patients and excluded those on dialysis, with a history of renal transplant, death during procedure, and without creatinine measures. Association with CA-AKI (rise in creatinine > 0.5 mg/dL) was tested using mixed-effects logistic regression. Variables associated with CA-AKI were used to generate a predictive model via a single classification tree. The variables selected by the classification tree were then validated by fitting a mixed-effects logistic regression model into the Vascular Quality Initiative dataset. Our derivation cohort included 7,043 patients, 3.5% of whom developed CA-AKI. After multivariate analysis, age (odds ratio [OR] 1.021, 95% confidence interval [CI] 1.004-1.040), female sex (OR 1.393, CI 1.012-1.916), glomerular filtration rate (GFR) < 30 mL/min (OR 5.068, CI 3.255-7.891), current smoking (OR 1.942, CI 1.067-3.535), chronic obstructive pulmonary disease (OR 1.402, CI 1.066-1.843), maximum abdominal aortic aneurysm (AAA) diameter (OR 1.018, CI 1.006-1.029), and presence of iliac artery aneurysm (OR 1.352, CI 1.007-1.816) were associated with increased odds of CA-AKI. Our risk prediction calculator demonstrated that patients with a GFR < 30 mL/min, females, and patients with a maximum AAA diameter of > 6.9 cm are at a higher risk of CA-AKI after EVAR. Using the Vascular Quality Initiative dataset (N=62,986), we found that GFR < 30 mL/min (OR 4.668, CI 4.007-5.85), female sex (OR 1.352, CI 1.213-1.507), and maximum AAA diameter > 6.9 cm (OR 1.824, CI 1.212-1.506) were associated with an increased risk of CA-AKI after EVAR. Herein, we present a simple and novel risk assessment tool that can be usedpreoperatively to identify patients at risk of CA-AKI after EVAR. Patients with a GFR <30 mL/min, maximum AAA diameter > 6.9 cm, and females who are undergoing EVAR may be at risk for CA-AKI after EVAR. Prospective studies are needed to determine the efficacy of our model.

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

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

Modern diagnostic approach to patients with abdominal aortic aneurysm.

Abdominal aortic aneurysm (AAA) is a relatively frequent and serious condition in vascular surgery. The diagnostic and indication process and its treatment are driven by the guidelines which dictate an intervention when the maximum AAA diameter is more than 55 mm. Nevertheless, this approach is not fully sufficient in all AAA cases and thus we have been seeking to develop a modern diagnostic tool using computer modeling and vascular wall stress analysis. The project has been ongoing in cooperation with engineers from VUT Brno (Brno University of Technology) and V&#352;B Ostrava (Technical University of Ostrava) for ten years. The design of the analytical tool was created during the first, experimental period of the project; this tool is able to assess vascular wall stress from regular CT scans using the finite element method. This primary model was gradually altered and its precision was increased considerably in the course of the years using data from mechanical and histological tests of AAA wall specimens harvested during open repairs. Additionally, other patient specific data are included in the analysis such as blood pressure, gender and material characteristics. The effectiveness of the method was evaluated in a pseudo-prospective study, showing clear superiority of the vascular wall stress analysis over the maximum diameter approach. The method was used in clinical practice for the first time during restrictions due to the COVID-19 pandemic; based on the analysis we were able to assess which AAA cases can be postponed and which had a high risk of rupture and an intervention was required despite the restrictions. The method achieved 100% sensitivity, and its specificity was also much better compared to the maximum diameter approach. The vascular wall stress analysis of AAA seems to be much more precise than the classic indication approach based only on the maximum diameter, and it can be used to determine the therapy based on patient specific parameters.

Positive association between calcium channel blocker treatment and persistent type II endoleak.

Type II endoleaks are the most common complication occurring after endovascular abdominal aortic aneurysm repair (EVAR). The aims of our study were to evaluate the impact of persistent type II endoleak on sac dynamics post-EVAR, and to study the association between non-anatomical factors including polymorphisms associated with abdominal aortic aneurysm (AAA) and persistent type II endoleak. The cohort comprises 210 patients undergoing EVAR between January 2010 and December 2018. A persistent type II endoleak was defined as any type II endoleak lasting longer than six months and included also a type II endoleak diagnosed after six months or more post-EVAR during the 36-month follow-up period confirmed with CT-angiography. Anteroposterior AAA maximum diameter and AAA volume were measured pre-EVAR and 36 months post-EVAR using CT-angiographic pictures. Sac progression was defined as at least 5 mm increase, sac regression as at least 5 mm decrease in the sac diameter in relation to the preprocedural diameter. Sociodemographic information, comorbidities, treatment, laboratory parameters, selected anatomical and genetic factors were all analyzed to determine their impact on persistent type II endoleak. The adjustments included age, hypertension, diabetes mellitus, dyslipidemia, sex, smoking in multivariate analyses. When postprocedural diameter and volume were evaluated, adjustments included also preprocedural diameter/volume. After exclusion, 178 patients with mean age 72.4±7.60 years remained for analysis. Persistent type II endoleak was found in 27.5% of patients (N.=49) and 2.94-times increased risk of sac progression in multivariate analysis (P=0.033). In multivariate analysis, AAA diameter in patients with persistent type II endoleak was 4.31 mm greater than in patients without (B=4.31; P=0.014); and its presence was also associated with 22.0 cm3 greater sac volume (B=22.0; P=0.034) compared to patients without persistent type II endoleak. Treatment with calcium channel blockers increased risk of persistent type II endoleak 2.11-times in multivariate analysis (OR=2.11; 95% CI: 1.05-4.25; P=0.037). No association between persistent type II endoleak and selected polymorphisms associated with AAA and other observed factors were found. Risk of persistent type II endoleak was more than doubled in patients taking calcium channel blockers. Patients with persistent type II endoleak had greater anteroposterior sac diameter and sac volume compared to patients without persistent type II endoleak.

Predictors of Abdominal Aortic Aneurysm Shrinkage after Endovascular Repair.

Recent studies demonstrate that patients with a shrinking abdominal aortic aneurysm (AAA), one-year after endovascular repair (EVAR), have better long-term outcomes than patients with a stable AAA. It is not known what factors determine whether an AAA will shrink or not. In this study, a range of parameters was investigated to identify their use in differentiating patients that will develop a shrinking AAA from those with a stable AAA one-year after EVAR. Hundred-seventy-four patients (67 shrinking AAA, 107 stable AAA) who underwent elective, infrarenal EVAR were enrolled between 2011–2018. Long-term survival was significantly better in patients with a shrinking AAA, compared to those with a stable AAA (p = 0.038). Larger preoperative maximum AAA diameter was associated with an increased likelihood of developing AAA shrinkage one-year after EVAR—whereas older age and larger preoperative infrarenal β angle were associated with a reduced likelihood of AAA shrinkage. However, this multivariate logistic regression model was only able to correctly identify 66.7% of patients with AAA shrinkage from the total cohort. This is not sufficient for implementation in clinical care, and therefore future research is recommended to dive deeper into AAA anatomy, and explore potential predictors using artificial intelligence and radiomics.

Abdominal Aortic Aneurysm Rupture Risk Assessment Using Machine Learning to Integrate Biomechanical, Geometrical, and Patient Characteristics

Introduction: The correlation between maximum diameter and rupture in abdominal aortic aneurysm (AAA) has been studied extensively, and a maximum AAA diameter of 55 mm in men or a diameter growth of more than 10 mm per year are accepted to indicate AAA repair. However, the maximum diameter criterion fails to describe AAA rupture risk in a patient specific manner and should therefore not directly be applied to individual patients. The poor sensitivity of diameter has been known for a long time and has stimulated the search for more patient specific risk indicators.

Abstract 9079: Omentin Reduces Angiotensin II-Induced Abdominal Aortic Aneurysm Formation in Apolipoprotein E Knockout Mice

Background: Abdominal aortic aneurysm (AAA) is a life-threatening disease worldwide. Obesity is associated with an increased risk of AAA. Omentin is an adipokine, which is downregulated by obesity. Here we investigated the effect of omentin on angiotensin (Ang) II-induced AAA formation in apolipoprotein-E knockout (apoE-KO) mice. Methods and Results: ApoE-KO mice were crossed with transgenic mice expressing the human omentin in fat tissue (OMT-Tg mice). ApoE-KO/OMT-Tg and apoE-KO mice were subjected to continuous Ang II infusion. ApoE-KO/OMT-Tg mice exhibited a reduced maximal diameter of AAA compared with apo-E KO mice evaluated by macroscopic and ultrasound analyses. ApoE-KO/OMT-Tg mice showed a reduction of elastic fiber degradation in aorta compared with apoE-KO mice. ApoE-KO/OMT-Tg mice also displayed reduced expression levels of matrix metalloproteinase (MMP) 9, MMP2, pro-inflammatory mediators and macrophage surface marker, F4/80, in aortic walls compared with apo-E-KO mice. Conversely, intravenous administration of adenoviral vectors expressing omentin (Ad-OMT) significantly reduced maximal diameter and elastic fiber degradation of abdominal aorta after Ang II infusion in apoE-KO mice compared with control Ad-β-gal treatment. Treatment of human monocyte-derived macrophages with omentin protein attenuated activity and expression of MMP9 and NF-κB phosphorylation after stimulation with lipopolysaccharide. Treatment of human aortic smooth muscle cells with omentin protein attenuated activity and expression of MMP2 after stimulation with tumor necrosis factor α. The suppressive effects of omentin on MMP9 and MMP2 expression in macrophages and vascular smooth muscle cells were reversed by inhibition of PI3-kinase/Akt signaling or blockade of integrin αVβ3. Finally, continuous administration of PI3-kinase inhibitor LY294002 reversed the suppressive effects of Ad-OMT on maximal diameter and elastic fiber degradation of abdominal aorta in apoE-KO mice after Ang II infusion. Conclusion: Our data indicate that omentin acts as an adipokine that can attenuate Ang II-induced development of AAA by reducing MMP9 and MMP2 expression through the integrin αVβ3/PI3-kinase/Akt signaling in the vascular wall.

Association of Diagnosis of Depression and Small Abdominal Aortic Aneurysm Growth

Depression is associated with an increased risk of cardiovascular events but its association with abdominal aortic aneurysm (AAA) progression is unknown. This study examined if a diagnosis of depression was association with more rapid AAA growth. Patients with small AAA measuring between 30 and 50 mm were recruited from surveillance programs at 4 Australian centres. Maximum AAA diameter was measured by ultrasound imaging using a standardised and reproducible protocol to monitor AAA growth. Depression was defined from medical records of treatment for depression at recruitment. Linear mixed effects modelling was performed to examine the independent association of depression with AAA growth. A propensity matched sub-analysis was performed. A total of 574 participants were included of whom 73 (12.7%) were diagnosed with depression. Participants were followed with a median of 3 (Inter-quartile range (IQR): 2, 5) ultrasound scans for a median of 2.1 (IQR: 1.1, 3.5) years. The unadjusted model suggested that annual AAA growth was non-significantly reduced (mean difference: -0.3 mm/year; 95% confidence interval (CI): -0.7, 0.2; P=0.26) in participants with a diagnosis of depression compared to other participants. After adjustment for covariates, depression was not significantly associated with AAA growth (mean difference: -0.3 mm/year; 95% CI: -0.8, 0.2; P=0.27). Findings were similar in the propensity matched sub-analysis. Sensitivity analyses investigating the impact of initial AAA diameter and follow up on the association of depression with AAA growth found no interaction. This study suggested that depression was not associated with faster AAA growth.

A Case of Thrombosed Inferior Mesenteric Artery Aneurysm Concomitant with Abdominal Aortic Aneurysm Treated by Endovascular Aneurysm Repair.

A 71-year-old man was referred to our hospital under a diagnosis of abdominal aortic aneurysm (AAA). The past history of the patient included a sigmoid colectomy at 64 years old for an ischemic colitis. The maximum diameter of AAA was still 45 mm, and the inferior mesenteric artery (IMA) was aneurysmal and was 30 mm in diameter and thrombosed. The growth rate in the diameter of IMA aneurysm was 5 mm per year for the last 3 years. The patient successfully underwent endovascular aneurysm repair (EVAR), and the postoperative course was good. At 5 years after EVAR, computed tomography revealed a decrease in the diameter of both aneurysms.

Validation of an assessment tool for estimation of abdominal aortic aneurysm compression in diagnostic ultrasound

The study investigated ultrasound (US) transducer push, tantamount to applied transducer pressure, during abdominal aortic aneurysm (AAA) US scanning in a simulated non-clinical setup.During an assessment of maximal AAA diameter on a three-dimensional print-based AAA phantom, US transducer push varied as much as 2000% (range: 0.52–12.45 kPa) amongst 16 experienced sonographers. The mean transducer push was 5.54 ± 3.91 kPa (CV = 0.71).Deformation of a standardized gel-pad allowed for transducer push calculation based on US images; Young’s modulus of the gel-pad was estimated to 44,26 N/m2.The method is theoretically validated in a safe and non-clinical environment. Future investigations with the aim of clinical validation of the gel-pad principle on AAA patients are suggested, including the objectification of the magnitude of an eventual transducer push-related error during US AAA diameter measurement.

Machine Learning-Based Pulse Wave Analysis for Early Detection of Abdominal Aortic Aneurysms Using In Silico Pulse Waves

An abdominal aortic aneurysm (AAA) is usually asymptomatic until rupture, which is associated with extremely high mortality. Consequently, the early detection of AAAs is of paramount importance in reducing mortality; however, most AAAs are detected by medical imaging only incidentally. The aim of this study was to investigate the feasibility of machine learning-based pulse wave (PW) analysis for the early detection of AAAs using a database of in silico PWs. PWs in the large systemic arteries were simulated using one-dimensional blood flow modelling. A database of in silico PWs representative of subjects (aged 55, 65 and 75 years) with different AAA sizes was created by varying the AAA-related parameters with major impacts on PWs—identified by parameter sensitivity analysis—in an existing database of in silico PWs representative of subjects without AAAs. Then, a machine learning architecture for AAA detection was trained and tested using the new in silico PW database. The parameter sensitivity analysis revealed that the AAA maximum diameter and stiffness of the large systemic arteries were the dominant AAA-related biophysical properties considerably influencing the PWs. However, AAA detection by PW indexes was compromised by other non-AAA related cardiovascular parameters. The proposed machine learning model produced a sensitivity of 86.8 % and a specificity of 86.3 % in early detection of AAA from the photoplethysmogram PW signal measured in the digital artery with added random noise. The number of false positive and negative results increased with increasing age and decreasing AAA size, respectively. These findings suggest that machine learning-based PW analysis is a promising approach for AAA screening using PW signals acquired by wearable devices.

The reproducibility of measuring maximum abdominal aortic aneurysm diameter from ultrasound images

BackgroundAccurate repeat assessment of the diameter of an abdominal aortic aneurysm (AAA) is important. This study investigated the reproducibility of different methods of measuring AAA diameter from ultrasound images.MethodsFifty AAA patients were assessed by ultrasound. Maximum AAA diameter was measured independently by three trained observers on two separate occasions using a standardised protocol. Five diameters were measured from each scan, three in the anterior–posterior (AP) and two in the transverse (TV) plane, including inner-to-inner (ITI), outer-to-outer (OTO) and leading edge-to-leading edge (LETLE). Intra- and inter-observer reproducibility were reported as reproducibility coefficients. Statistical comparison of methods was performed using linear mixed effects models.ResultsIntra-observer reproducibility coefficients (AP LETLE 2.2 mm; AP ITI 2.4 mm; AP OTO 2.6 mm) were smaller than inter-observer reproducibility coefficients (AP LETLE 4.6 mm: AP ITI 4.5; and AP OTO 4.8 mm). There was no statistically significant difference in intra-observer reproducibility of three types of measurements performed in the AP plane. Measurements obtained in the TV plane had statistically significant worse intra-observer reproducibility than those performed in the AP plane.ConclusionsThis study suggests that the comparison of maximum AAA diameter between repeat images is most reproducibly performed by a single trained observer measuring diameters in the AP plane.