Screening for abdominal aortic aneurysms

Multimodality magnetic resonance evaluating the effect of enhanced physical exercise on the growth rate, flow haemodynamics, aneurysm wall and ventricular-aortic coupling of patients with small abdominal aortic aneurysms (AAA MOVE trial): a study protocol for an open-label randomised controlled trial

INTRODUCTION

The best lifestyle for small abdominal aortic aneurysms (sAAA) is essential for its conservative management. Physical exercise can improve the cardiopulmonary function of the patients, but it remains unclear which specific type of exercise is most beneficial for individuals with sAAA. The current study was designed to investigate the effect of physician-guided enhanced physical exercise programme on the aorto-cardiac haemodynamic environment, aneurysm sac wall, cardiac function and growth rate of sAAA by multimodality MRI.

METHODS AND ANALYSIS

AAA MOVE study is a prospective, parallel, equivalence, randomised controlled trial. Eligible individuals will be recruited if they are diagnosed with sAAA (focal dilation of abdominal aorta with maximum diameter <5 cm), without contraindication for MRI scanning, or severe heart failure, or uncontrolled arrhythmia. Participants will be randomly allocated to intervention group (physician-guided enhanced physical exercise programme: mainly aerobic training) and control group (standard clinical care) separately in a 1:1 ratio. The primary outcome is 12-month growth rate of sAAA. The first set of secondary outcomes involve multimodality MRI parameters covering flow haemodynamics, aortic wall inflammation and cardiac function. The other secondary outcome (safety end point) is a composite of exercise-related injury, aneurysm rupture and aneurysm intervention. Follow-up will be conducted at 6 and 12 months after intervention.

ETHICS AND DISSEMINATION

This study was approved by the Ethics Committee on Biomedical Research of West China Hospital (approval number: 2023-783) on 16 June 2023. Main findings from the trial will be disseminated through presentations at conferences, peer-reviewed publications and directly pushed to smartphone of participants.

TRIAL REGISTRATION NUMBER

ChiCTR2300073334.

An evidence update to explore molecular targets and protective mechanisms of apigenin against abdominal aortic aneurysms based on network pharmacology and experimental validation

Abdominal aortic aneurysms (AAA) is a life-threatening disease and the incidence of AAA is still on the rise in recent years. Numerous studies suggest that dietary moderate consumption of polyphenol exerts beneficial effects on cardiovascular disease. Apigenin (API) is a promising dietary polyphenol and possesses potent beneficial effects on our body. Although our previous study revealed protective effects of API on experimental AAA formation, up till now few studies were carried out to further investigate its involved molecular mechanisms. In the present study, network pharmacology combined molecular docking and experimental validation was used to explore API-related therapeutic targets and mechanisms in the treatment of AAA. Firstly, we collected 202 API-related therapeutic targets and 2475 AAA-related pathogenetic targets. After removing duplicates, a total of 68 potential therapeutic targets were obtained. Moreover, 5 targets with high degree including TNF, ACTB, INS, JUN, and MMP9 were identified as core targets of API for treating AAA. In addition, functional enrichment analysis indicated that API exerted pharmacological effects in AAA by affecting versatile mechanisms, including apoptosis, inflammation, blood fluid dynamics, and immune modulation. Molecular docking results further supported that API had strong affinity with the above core targets. Furthermore, protein level of core targets and related pathways were evaluated in a Cacl2-induced AAA model by using western blot and immunohistochemistry. The experimental validation results demonstrated that API significantly attenuated phosphorylation of JUN and protein level of predicted core targets. Taken together, based on network pharmacological and experimental validation, our study systematically explored associated core targets and potential therapeutic pathways of API for AAA treatment, which could supply valuable insights and theoretical basis for AAA treatment.

Unpacking the Complexities of a Silent Killer

An abdominal aortic aneurysm (AAA) is a life-threatening condition that affects millions of people worldwide [...].

Ascending Aortic Pseudoaneurysm Following Aortic Valve Replacement: A Case Report and Literature Review

Introduction: Ascending aortic pseudoaneurysm (AAP) rupture is a surgical emergency that needs immediate medical and surgical attention and treatment. This rupture can be caused by a variety of risk factors. Prior cardiovascular surgery is a common cause, and prior aortic valve operation is a rare cause. Case Presentation: In this case report, we describe a 47-year-old male with AAP who had a history of aortic valve replacement because of aortic stenosis.

Prognostic model for survival of patients with abdominal aortic aneurysms treated with endovascular aneurysm repair

The role of endovascular aneurysm repair (EVAR) in patients with asymptomatic abdominal aortic aneurysm (AAA) who are unfit for open surgical repair has been questioned. The impending risk of aneurysm rupture, the risk of elective repair, and the life expectancy must be balanced when considering elective AAA repair. This retrospective observational cohort study included all consecutive patients treated with standard EVAR for AAA at a referral centre between 2001 and 2020. A previously published predictive model for survival after EVAR in patients treated between 2001 and 2012 was temporally validated using patients treated at the same institution between 2013 and 2020 and updated using the overall cohort. 558 patients (91.2% males, mean age 74.9 years) were included. Older age, lower eGFR, and COPD were independent predictors for impaired survival. A risk score showed good discrimination between four risk groups (Harrel's C = 0.70). The 5-years survival probabilities were only 40% in "high-risk" patients, 68% in "moderate-to-high-risk" patients, 83% in "low-to-moderate-risk", and 89% in "low-risk" patients. Low-risk patients with a favourable life expectancy are likely to benefit from EVAR, while high-risk patients with a short life expectancy may not benefit from EVAR at the current diameter threshold.

Identification of biomarkers and analysis of infiltrated immune cells in stable and ruptured abdominal aortic aneurysms

Objectives

The mortality rate of abdominal aortic aneurysm (AAA) is extremely high in the older population. This study aimed to identify potential biomarkers of AAA and aortic rupture and analyze infiltration of immune cells in stable and ruptured AAA samples.

Methods

Raw data of GSE47472, GSE57691, and GSE98278 were downloaded. After data processing, the co-expression gene networks were constructed. Gene Ontology and pathway enrichment analysis of AAA- and aortic rupture-related gene modules were conducted using the Database for Annotation, Visualization, and Integrated Discovery. Gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) were used for further enrichment analysis. The CIBERSORT tool was used to analyze the relative abundance of immune cells in samples. Differentially expressed immune-related genes were analyzed between different samples. Predictive models were constructed via extreme gradient boosting, and hub genes were identified according to feature importance.

Results

Blue and yellow modules were significantly related to AAA, and genes in these modules were associated with the aortic wall and immune response, respectively. In terms of aortic rupture, the most relevant module was significantly enriched in the inflammatory response. The results of GSEA and GSVA suggested that immune cells and the inflammatory response were involved in the development of AAA and aortic rupture. There were significant differences in the infiltration of immune cells and expression levels of immune-related genes among different samples. NFKB1 might be an important transcription factor mediating the inflammatory response of AAA and aortic rupture. After the construction of a predictive model, CD19, SELL, and CCR7 were selected as hub genes for AAA whereas OAS3, IFIT1, and IFI44L were identified as hub genes for aortic rupture.

Conclusion

Weakening of the aortic wall and the immune response both contributed to the development of AAA, and the inflammatory response was closely associated with aortic rupture. The infiltration of immune cells was significantly different between different samples. NFKB1 might be an important transcription factor in AAA and aortic rupture. CD19, SELL, and CCR7 had potential diagnostic value for AAA. OAS3, IFIT1, and IFI44L might be predictive factors for aortic rupture.

Factors Associated with Preference of Choice of Aortic Aneurysm Repair in the PReference for Open Versus Endovascular repair of AAA (PROVE-AAA) study

OBJECTIVE

Patients can choose between open repair and endovascular repair of abdominal aortic aneurysm (AAA). However, the factors associated with patient preference for one repair type over another are not well characterized. Here we assess the factors associated with preference of choice for open or endovascular AAA repair among veterans exposed to a decision aid to help with choosing surgical treatment.

METHODS

Across 12 VA hospitals, veterans received a decision aid covering domains including patient information sources and understanding preference. Veterans were then given a series of surveys at different timepoints examining their preferences for open versus endovascular AAA repair. Questions from the preference survey were used in analyses of patient preference. Results were analyzed using chi-squared tests. A logistic regression was performed to assess factors associated with preference for open repair or preference for endovascular repair.

RESULTS

A total of 126 veterans received a decision aid informing them of their treatment choices, after which 121 completed all preference survey questions; five veterans completed only part of the instruments. Overall, veterans who preferred open repair were typically younger (70 vs 73, p=0.02), with similar rates of common comorbidities (coronary disease 16% vs 28%, p=0.21), and similar aneurysms compared to those who preferred endovascular repair (6.0 cm versus 5.7 cm, p=0.50). Veterans in both preference categories (28% of veterans preferring EVAR, 48% of veterans preferring open repair) reported "taking their doctor's" advice as the "top-box" response for the single most important factor influencing their decision. When comparing the tradeoff between less invasive surgery and higher risk of long-term complications, more than half of veterans preferring EVAR reported invasiveness as more important compared with approximately one in ten of those preferring open repair (53% versus 12%, p<0.001). Shorter recovery was an important factor for the endovascular repair group (74%) and not important in the open repair group (76%), p=0.5). In multivariable analyses, valuing a short hospital stay (OR=12.4, 95% CI 1.13-135.7) and valuing a shorter recovery (OR15.72, 95% CI 1.03-240.2) were associated with greater odds of preference for endovascular repair, while finding these characteristics not important were associated with greater odds of preference for open repair.

CONCLUSIONS

When faced with the decision of open repair versus endovascular repair, veterans who valued a shorter hospital stay and a shorter recovery were more likely to prefer endovascular repair, while those more concerned about long-term complications preferred open repair. Veterans typically value the advice of their surgeon over their own beliefs and preference. These findings need to be considered by surgeons as they guide their patients to a shared decision.

AAA Revisited: A Comprehensive Review of Risk Factors, Management, and Hallmarks of Pathogenesis

Despite declining incidence and mortality rates in many countries, the abdominal aortic aneurysm (AAA) continues to represent a life-threatening cardiovascular condition with an overall prevalence of about 2-3% in the industrialized world. While the risk of AAA development is considerably higher for men of advanced age with a history of smoking, screening programs serve to detect the often asymptomatic condition and prevent aortic rupture with an associated death rate of up to 80%. This review summarizes the current knowledge on identified risk factors, the multifactorial process of pathogenesis, as well as the latest advances in medical treatment and surgical repair to provide a perspective for AAA management.

Kunming mouse strain is less susceptible to elastase‐induced abdominal aortic aneurysms

Background

Porcine pancreatic elastase (PPE) is successfully used to induce abdominal aortic aneurysm (AAA) in mice. However, differences between mouse strains in susceptibility to PPE induction have been reported. Kunming mouse is one of the most frequently used strains in China but whether it is suitable for induction of AAA by PPE application remains unclear.

Methods

PPE infusion (1.5 units/ml) in temporary controlled aorta was performed to induce AAAs in both C57BL/6J and Kunming mice. Phosphate‐buffered saline (PBS) application was used as vehicle control. The aorta diameters of all mice were measured at days 0 and 14 after surgery to evaluate the AAA formation.

Results

After 14 days of PPE or PBS infusion, all mice were sacrificed and aorta tissues were collected for histological staining analysis. At the 14th day after infusion, PPE successfully induced aortic dilation in Kunming mice and typical AAA in C57BL/6J mice. The aorta diameter increased by 0.23 mm in Kunming mice after PPE infusion, while it was 0.72 mm in the C57BL/6J strain. PPE induced mild elastin degradation, smooth muscle cell (SMC) depletion and mural leucocyte infiltration in Kunming mice, but in PPE‐sensitive C57BL/6J mice, it induced total loss of SMCs, elastin disappearance and diffused infiltrated leucocytes in aortic aneurysmal segments. The effects of PPE in inducing angiogenesis and upregulating matrix metalloproteinase 2 and 9 expression in Kunming mice were also weaker than that in C57BL/6J mice.

Conclusion

At the reported dose of PPE, Kunming mouse is not as susceptible to AAA formation as C57BL/6J mice. The failure of PPE to induce AAA formation in Kunming mice may be associated to its inability to boost a strong inflammatory response.

Systematic review of plasma/packed red blood cell ratio on survival in ruptured abdominal aortic aneurysms

BACKGROUND

The ideal perioperative fluid resuscitation for patients with ruptured abdominal aortic aneurysms (rAAAs) is unknown. It has been shown in trauma studies that a higher ratio of plasma and platelets to packed red blood cells confers a mortality benefit. Controversy remains whether this is true also in the rAAA population. The objective of the present study was to investigate the benefit of a greater ratio of plasma/packed red blood cells in patients with rAAAs.

METHODS

A health sciences librarian searched four electronic databases, including PubMed, Embase, Cochrane, and ClinicalTrials.gov, using concepts for the terms "fluid resuscitation," "survival," and "ruptured abdominal aortic aneurysm." Two reviewers independently screened the studies that were identified through the search strategy and read in full any study that was potentially relevant. Studies were included if they had compared the mortality of patients with rAAAs who had received a greater ratio of plasma to other component therapy with that of patients who had received a lower ratio. The risk of bias was assessed using the ROBINS-I (risk of bias in nonrandomized studies of interventions) validated tool, and evidence quality was rated using the GRADE (grades of recommendation assessment, development, and evaluation) profile. No data synthesis or meta-analysis was planned or performed, given the anticipated paucity of research on this topic and the high degree of heterogeneity of available studies.

RESULTS

Our search identified seven observational studies for inclusion in the present review. Of these seven studies, three found an associated decrease in mortality with a greater ratio of plasma to packed red blood cells. The remaining four found no significant differences. The overall risk of bias was serious, and the evidence quality was very low.

CONCLUSIONS

Overall, the findings from the available studies would suggest that for patients who have undergone open surgery for a rAAA, mortality tends to be decreased when the amount of plasma transfused perioperatively is similar to the amount of packed red blood cells. However, the included studies reported very low-quality evidence based solely on highly heterogeneous observational studies, and further research is warranted.

Abdominal aortic aneurysms

An abdominal aortic aneurysm (AAA) is a localized dilatation of the infrarenal aorta. AAA is a multifactorial disease, and genetic and environmental factors play a part; smoking, male sex and a positive family history are the most important risk factors, and AAA is most common in men >65 years of age. AAA results from changes in the aortic wall structure, including thinning of the media and adventitia due to the loss of vascular smooth muscle cells and degradation of the extracellular matrix. If the mechanical stress of the blood pressure acting on the wall exceeds the wall strength, the AAA ruptures, causing life-threatening intra-abdominal haemorrhage - the mortality for patients with ruptured AAA is 65-85%. Although AAAs of any size can rupture, the risk of rupture increases with diameter. Intact AAAs are typically asymptomatic, and in settings where screening programmes with ultrasonography are not implemented, most cases are diagnosed incidentally. Modern functional imaging techniques (PET, CT and MRI) may help to assess rupture risk. Elective repair of AAA with open surgery or endovascular aortic repair (EVAR) should be considered to prevent AAA rupture, although the morbidity and mortality associated with both techniques remain non-negligible.

Association of statins with aortic, peripheral, and visceral artery aneurysm development

Objectives

Prior studies examining the effects of statins on arterial aneurysm development and progression yielded conflicting results due to their smaller size and presence of residual confounders. The objective of this study is to examine the association of statins with risk of being diagnosed with aortic, peripheral, and visceral artery aneurysm.

Methods

This was a retrospective cohort study of Tricare enrollees (from 1 October 2003 to 31 March 2012). Main outcomes were diagnosis of aortic, peripheral, or visceral artery aneurysm and undergoing aortic aneurysm repair procedure during follow-up period. Using 115 baseline characteristics, we generated a propensity score to match statin users and nonusers and examine the odds of outcomes (primary analysis). Secondary analysis examined outcomes at various subcohorts.

Results

Out of 10,910 statin users and 49,545 nonusers, we propensity score-matched 6728 pairs of statin users and nonusers. Statin users and nonusers had similar odds of being diagnosed with aortic, peripheral, and visceral artery aneurysms (odds ratio [OR]: 1.06, 95% confidence interval [95% CI]: 0.85–1.33) and of undergoing aortic aneurysm repair procedures (OR: 0.54, 95% CI: 0.22–1.35). Secondary analysis showed a tendency toward fewer aortic aneurysm procedures among statin users that did not reach statistical significance. However, high-intensity statin users in comparison to non-intensive statin users had higher adjusted odds of aortic, peripheral, and visceral artery aneurysms (OR: 1.76, 95% CI: 1.37–2.25, p < .0001).

Conclusions

This study does not support a clinically significant benefit or harm from statins regarding development of arterial aneurysm. However, secondary analyses may support the hypothesis proposed by previous research proposing a bidirectional role for statins.

B-Cell Depletion Promotes Aortic Infiltration of Immunosuppressive Cells and Is Protective of Experimental Aortic Aneurysm

OBJECTIVE

B-cell depletion therapy is widely used for treatment of cancers and autoimmune diseases. B cells are abundant in abdominal aortic aneurysms (AAA); however, it is unknown whether B-cell depletion therapy affects AAA growth. Using experimental models of murine AAA, we aim to examine the effect of B-cell depletion on AAA formation.

APPROACH AND RESULTS

Wild-type or apolipoprotein E-knockout mice were treated with mouse monoclonal anti-CD20 or control antibodies and subjected to an elastase perfusion or angiotensin II infusion model to induce AAA, respectively. Anti-CD20 antibody treatment significantly depleted B1 and B2 cells, and strikingly suppressed AAA growth in both models. B-cell depletion resulted in lower circulating IgM levels, but did not affect the levels of IgG or cytokine/chemokine levels. Although the total number of leukocyte remained unchanged in elastase-perfused aortas after anti-CD20 antibody treatment, the number of B-cell subtypes was significantly lower. Interestingly, plasmacytoid dendritic cells expressing the immunomodulatory enzyme indole 2,3-dioxygenase were detected in the aortas of B-cell-depleted mice. In accordance with an increase in indole 2,3-dioxygenase+ plasmacytoid dendritic cells, the number of regulatory T cells was higher, whereas the expression of proinflammatory genes was lower in aortas of B-cell-depleted mice. In a coculture model, the presence of B cells significantly lowered the number of indole 2,3-dioxygenase+ plasmacytoid dendritic cells without affecting total plasmacytoid dendritic cell number.

CONCLUSIONS

The present results demonstrate that B-cell depletion protects mice from experimental AAA formation and promotes emergence of an immunosuppressive environment in aorta.

Comparison of the serum lipidome in patients with abdominal aortic aneurysm and peripheral artery disease

BACKGROUND

Currently, the relationship between circulating lipids and abdominal aortic aneurysm (AAA) is unclear. We conducted a lipidomic analysis to identify serum lipids associated with AAA presence. Secondary analyses assessed the ability of models incorporating lipidomic features to improve stratification of patient groups with and without AAA beyond traditional risk factors.

METHODS AND RESULTS

Serum lipids were profiled via liquid chromatography tandem mass spectrometry analysis of serum from 161 patients with AAA and 168 controls with peripheral artery disease. Binary logistic regression was used to identify AAA-associated lipids. Classification models were created based on a combination of (1) traditional risk factors only or (2) lipidomic features and traditional risk factors. Model performance was assessed using receiver operator characteristic curves. Three diacylglycerols and 7 triacylglycerols were associated with AAA. Combining lipidomic features with traditional risk factors significantly improved stratification of AAA and peripheral artery disease groups when compared with traditional risk factors alone (mean area under the receiver operator characteristic curve [95% confidence interval], 0.760 [0.756-0.763] and 0.719 [0.716-0.723], respectively; P<0.05).

CONCLUSIONS

A group of linoleic acid containing triacylglycerols and diacylglycerols were significantly associated with AAA presence. Inclusion of lipidomic features in multivariate analyses significantly improved prediction of AAA presence when compared with traditional risk factors alone.

Incidental abdominal aneurysms: a retrospective study of 13,115 patients who underwent a computed tomography scan

We evaluated the frequency and outcomes of abdominal aortic aneurysm (AAA) in Qatar. Data were collected retrospectively between 2004 and 2008 for all adult patients who underwent abdominal computed tomographic scanning for any reason. Patients with AAA were followed up for 3 years for aneurysmal rupture and mortality. Of the 13,115 patients screened, 61 (0.5%) patients had abdominal aneurysms. Most (82%) patients with AAA were male with mean age of 67 ± 12 years. The incidence of AAA substantially increased with age. Cardiovascular risk factors were prevalent among patients with AAA. The main location of AAA was infrarenal (67%), followed by thoracoabdominal (23%). The mean AAA diameter was 5.3 ± 2.5 cm. The rate of AAA rupture was 8% with a mortality rate of 60%; 80% of these were infrarenal, and 80% of them had a diameter of ≥5.5 cm. Overall mortality was 33%. This large study addressed the impact of screening for AAA in a population with high cardiovascular burden.