Prevalence of risk factors, coronary and systemic atherosclerosis in abdominal aortic aneurysm: comparison with high cardiovascular risk population

Demographical and Clinical Factors Predictive for Aortic Dilatation. When should we be Concerned about the Size?

Background

Thoracic aortic aneurysms are often an accidental finding and result from a degenerative process. Medical therapy includes pharmacological control of arterial hypertension and smoking cessation, that slows the growth of aneurysms. An association between the dilatation of the ascending and abdominal aorta has been already reported. The aim of the study was to identify possible demographic and clinical factors that may implicate further imaging diagnostics in patients with ascending aorta dilatation.

Methods

There were 181 (93 (53%) males and 88 (47%) females) patients with a median age of 54 (41-62) years who underwent cardiac magnetic resonance due to non-vascular diseases, were enrolled into retrospective analysis.

Results

Multivariable analysis revealed ascending aorta dilatation (odds ratios (OR) = 7.45, 95% confidence interval (CI): 1.98-28.0, p = 0.003) and co-existence of coronary artery disease (OR = 8.68, 95% CI: 2.15-35.1, p = 0.002) as significant predictors for thoracic descending aorta dilatation. In patients with abdominal aorta dilatation, the multivariable analysis showed a predictive value of ascending aortic dilatation (OR = 14.8, 95% CI: 2.36-92.8, p = 0.004) and age (OR = 1.04, 95% CI: 1.00-1.08, p = 0.027). In addition, cut-off values were established for age groups determining the risk of thoracic aorta dilatation over 49 years and abdominal aorta dilatation over 54 years.

Conclusions

The results of our analysis showed predictive factors, including ascending aorta dilatation and co-existence of coronary artery disease, particularly over 49 years of age for thoracic, while ascending aorta dilatation and age, particularly over 54 years, for abdominal aorta dilatation. These features may be considered to increase clinical vigilance in patients with aortic diameter abnormalities.

Apolipoprotein E (ApoE) Rescues the Contractile Smooth Muscle Cell Phenotype in Popliteal Artery Aneurysm Disease

Popliteal artery aneurysm (PAA) is the most frequent peripheral aneurysm, primarily seen in male smokers with a prevalence below 1%. This exploratory study aims to shed light on cellular mechanisms involved in PAA progression. Sixteen human PAA and eight non-aneurysmatic popliteal artery samples, partially from the same patients, were analyzed by immunohistochemistry, fluorescence imaging, Affymetrix mRNA expression profiling, qPCR and OLink proteomics, and compared to atherosclerotic (n = 6) and abdominal aortic aneurysm (AAA) tissue (n = 19). Additionally, primary cell culture of PAA-derived vascular smooth muscle cells (VSMC) was established for modulation and growth analysis. Compared to non-aneurysmatic popliteal arteries, VSMCs lose the contractile phenotype and the cell proliferation rate increases significantly in PAA. Array analysis identified APOE higher expressed in PAA samples, co-localizing with VSMCs. APOE stimulation of primary human PAA VSMCs significantly reduced cell proliferation. Accordingly, contractile VSMC markers were significantly upregulated. A single case of osseous mechanically induced PAA with a non-diseased VSMC profile emphasizes these findings. Carefully concluded, PAA pathogenesis shows similar features to AAA, yet the mechanisms involved might differ. APOE is specifically higher expressed in PAA tissue and could be involved in VSMC phenotype rescue.

Circulating Inflammatory Mediators and Genetic Polymorphisms of Inflammation Mediators and Their Association with Factors Related to Abdominal Aortic Aneurysm: A Systemic Review and Meta-Analysis

Background

This study aimed to explore the levels of circulating inflammatory factors CRP, IL-6, IL-10 and TNF- α based on the literature review. This study also examined the influence of single nucleotide polymorphism (SNP) sites on the susceptibility of abdominal aortic aneurysm (AAA) using meta-analysis and intended to provide additional information on pathogenesis of AAA research.

Methods

Electronic databases including PubMed and Web of Science were systemically searched to collect the information on AAA, inflammatory factors such as CRP, IL-6, IL-10, TNF- α and the SNP sites for data extraction. Altogether six SNPs in four genes (rs3091244, CRP; rs1800947, CRP; rs1205, CRP; rs1800795, IL-6; rs1800896, IL-10; and rs1800629, TNF) were assessed.

Results

This study enrolled altogether 41 relevant investigations involving 9,007 AAA patients to carry out meta-analysis. According to pooled analysis, circulating CRP and IL-6 levels were shown to be related to the AAA, while plasma IL-10 and TNF- α levels were not associated with AAA. The circulating CRP level standard mean difference (SMD) was 0.30 (95% confidence interval (CI): 0.17-0.43), the IL-6 level SMD was 0.34 (95% CI: 0.20-0.49), the IL-10 level SMD was -0.01 (95% CI: -0.09-0.06), and the TNF- α level SMD was 0.09 (95% CI: 0.00-0.19). Similarly, the odds ratio (OR) of rs3091244 (CRP) under the recessive gene model was 1.70 (95% CI: 1.13-2.57). In addition, individuals with A and T mutant genes at locus rs3091244 might have a higher tendency of AAA susceptibility than those with C allele. Consecutively, the OR was 0.91 (95% CI: 0.51-0.97) for rs1800795 (IL-6) locus in the allele model, and individuals with G mutant gene at locus rs1800795 (IL-6) might be less susceptible to AAA than those with C allele. Meanwhile, the rs1800896 (IL-10) locus had a positive association under the five statistical models, and individuals with A mutant gene at locus rs1800896 might have a higher susceptibility to AAA than those with G allele. Nevertheless, the rs1800947 (CRP), rs1205 (CRP), and rs1800629 (TNF) loci did not have positive correlation under the five statistical models, with no statistical significance. The results indicate that the gene polymorphisms at rs1800629, rs1800947, and rs1205 loci were not related to the AAA susceptibility.

Conclusions

Gene polymorphisms in certain known inflammatory mediators related to AAA susceptibility might serve as potential predictive biomarkers for clinical applications. Moreover, SNP of inflammatory mediators relevant to abdominal aortic aneurysmal formation and progression need extensive investigations to confirm these results.

JNK2 Gene Silencing for Elastic Matrix Regenerative Repair

Elastic fibers do not naturally regenerate in many proteolytic disorders, such as in abdominal aortic aneurysms, and prevent restoration of tissue homeostasis. We have shown drug-based attenuation of the stress-activated protein kinase, JNK-2 to stimulate elastic matrix neoassembly and to attenuate cellular proteolytic activity. We now investigate if JNK2 gene knockdown with small interfering RNA (siRNA) provides greater specificity of action and improved regenerative/antiproteolytic outcomes in a proteolytic injury culture model of rat aneurysmal smooth muscle cells (EaRASMCs). A siRNA dose of 12.5 nM delivered with a transfection reagent significantly enhanced downstream elastic fiber assembly and maturation versus untreated EaRASMC cultures. The optimal siRNA dose was also delivered as a complex with a polymeric transfection vector, polyethyleneimine (PEI) in preparation for future in vivo delivery. Linear 25 kDa PEI-siRNA (5:1 molar ratio of amine to phosphate) and linear 40 kDa PEI-siRNA (2.5:1 ratio) were effective in downregulating the JNK2 gene, and significantly increasing expression of elastic fiber assembly proteins, and decreases in elastolytic matrix metalloprotease-2 versus treatment controls to significantly increase mature elastic fiber assembly. The current work has identified siRNA dosing and siRNA-PEI complexing conditions that are safe and efficient in stimulating processes contributing to improved elastic matrix neoassembly via JNK2 gene knockdown. The results represent a mechanistic basis of a broader therapeutic approach to reverse elastic matrix pathophysiology in tissue disorders involving aberrations of elastic matrix homeostasis, such as in aortic aneurysms. Impact statement The elastic matrix and elastic fibers are key components of the structural extracellular matrix of elastic tissues and are essential to their stretch and recoil and to maintain healthy cell phenotype. Regeneration and repair of elastic matrix is naturally poor and impaired and is an unresolved challenge in tissue engineering. In this work, we investigate a novel gene silencing approach based on inhibiting the JNK2 gene, which provides significant downstream benefits to elastic fiber assembly and maturation. Combined with novel delivery strategies such as nanoparticles, we expect our approach to effect in situ elastic matrix repair in the future.

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.

Screening for Prevalence of Abdominal Aortic Aneurysm During Transthoracic Echocardiography in Patient With Significant Coronary Artery Disease

Background

Prevalence of abdominal aortic aneurysm (AAA) has ethnic differences, and coronary artery disease (CAD) shares several risk factors with AAA. Sparse Indian data are available on this. We evaluated the prevalence of AAA during transthoracic echocardiography (TTE) and risk factors of AAA in patients with CAD.

Methods

This was a prospective observational study carried out in the cardiology department at a tertiary care center from January 1, 2017 to November 30, 2017. All patients with CAD/acute coronary syndrome (ACS) were included in the study, and patients with AAA due to other etiology were excluded. Screening for an AAA was performed directly using an echocardiographic 3.5-MHz cardiac probe.

Results

A total of 526 patients were screened; and AAA was present in 25 (4.8%) of CAD patients. Smoking, hypertension and hyperlipidemia were predominant risk factors for AAA in our study, but were not statistically significant because same risk factors were also prevalent in the comparison group. Diabetes, peripheral vascular disease and family history were statistically significant risk factors for AAA in our study. The mean size of AAA was 34 mm.

Conclusions

Presence of AAA is significantly higher among CAD patients. CAD shares several risk factors with AAA. Therefore, opportunistic examination of the abdominal aorta during routine TTE could be an effective way of screening. Diabetes mellitus, peripheral artery disease and family history were the significant associated risk factors of AAA in CAD patients.

Discovery of potential biomarkers for human atherosclerotic abdominal aortic aneurysm through untargeted metabolomics and transcriptomics

Abdominal aortic aneurysm (AAA) and atherosclerosis (AS) have considerable similarities in clinical risk factors and molecular pathogenesis. The aim of our study was to investigate the differences between AAA and AS from the perspective of metabolomics, and to explore the potential mechanisms of differential metabolites via integration analysis with transcriptomics. Plasma samples from 32 AAA and 32 AS patients were applied to characterize the metabolite profiles using untargeted liquid chromatography-mass spectrometry (LC-MS). A total of 18 remarkably different metabolites were identified, and a combination of seven metabolites could potentially serve as a biomarker to distinguish AAA and AS, with an area under the curve (AUC) of 0.93. Subsequently, we analyzed both the metabolomics and transcriptomics data and found that seven metabolites, especially 2'-deoxy-D-ribose (2dDR), were significantly correlated with differentially expressed genes. In conclusion, our study presents a comprehensive landscape of plasma metabolites in AAA and AS patients, and provides a research direction for pathogenetic mechanisms in atherosclerotic AAA.

Circular RNA Expression: Its Potential Regulation and Function in Abdominal Aortic Aneurysms

Abdominal aortic aneurysms (AAAs) have posed a great threat to human life, and the necessity of its monitoring and treatment is decided by symptomatology and/or the aneurysm size. Accumulating evidence suggests that circular RNAs (circRNAs) contribute a part to the pathogenesis of AAAs. circRNAs are novel single-stranded RNAs with a closed loop structure and high stability, having become the candidate biomarkers for numerous kinds of human disorders. Besides, circRNAs act as molecular "sponge" in organisms, capable of regulating the transcription level. Here, we characterize that the molecular mechanisms underlying the role of circRNAs in AAA development were further elucidated. In the present work, studies on the biosynthesis, bibliometrics, and mechanisms of action of circRNAs were aims comprehensively reviewed, the role of circRNAs in the AAA pathogenic mechanism was illustrated, and their potential in diagnosing AAAs was examined. Moreover, the current evidence about the effects of circRNAs on AAA development through modulating endothelial cells (ECs), macrophages, and vascular smooth muscle cells (VSMCs) was summarized. Through thorough investigation, the molecular mechanisms underlying the role of circRNAs in AAA development were further elucidated. The results demonstrated that circRNAs had the application potential in the diagnosis and prevention of AAAs in clinical practice. The study of circRNA regulatory pathways would be of great assistance to the etiologic research of AAAs.

Simvastatin Attenuates Abdominal Aortic Aneurysm Formation Favoured by Lack of Nrf2 Transcriptional Activity

Surgical intervention is currently the only option for an abdominal aortic aneurysm (AAA), preventing its rupture and sudden death of a patient. Therefore, it is crucial to determine the pathogenic mechanisms of this disease for the development of effective pharmacological therapies. Oxidative stress is said to be one of the pivotal factors in the pathogenesis of AAAs. Thus, we aimed to evaluate the significance of nuclear factor erythroid 2-related factor 2 (Nrf2) transcriptional activity in the development of AAA and to verify if simvastatin, administered as pre- and cotreatment, may counteract this structural malformation. Experiments were performed on mice with inhibited transcriptional activity of Nrf2 (tKO) and wild-type (WT) counterparts. We used a model of angiotensin II- (AngII-) induced AAA, combined with a fat-enriched diet. Mice were administered with AngII or saline for up to 28 days via osmotic minipumps. Simvastatin administration was started 7 days before the osmotic pump placement and then continued until the end of the experiment. We found that Nrf2 inactivation increased the risk of development and rupture of AAA. Importantly, these effects were reversed by simvastatin in tKO mice, but not in WT. The abrupt blood pressure rise induced by AngII was mitigated in simvastatin-treated animals regardless of the genotype. Simvastatin-affected parameters that differed between the healthy structure of the aorta and aneurysmal tissue included immune cell infiltration of the aortic wall, VCAM1 mRNA and protein level, extracellular matrix degradation, TGF-β1 mRNA level, and ERK phosphorylation, but neither oxidative stress nor the level of Angiotensin II Type 1 Receptor (AT1R). Taken together, the inhibition of Nrf2 transcriptional activity facilitates AAA formation in mice, which can be prevented by simvastatin. It suggests that statin treatment of patients with hypercholesterolemia might have not only a beneficial effect in terms of controlling atherosclerosis but also potential AAA prevention.

Circular RNA expression profile and its potential regulative role in human abdominal aortic aneurysm

Background

This study aimed to identify the differentially expressed circular RNAs (circRNAs) between human abdominal aortic aneurysm (AAA) and the control group.

Methods

High-throughput sequencing was applied to determine the circRNA expression profiles of 4 paired aortic samples. Real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was carried out to testify 6 randomly selected dysregulated circRNAs. Kyoto Encyclopedia of Genes and Genomes and Gene ontology (GO) analysis were conducted for functional annotation of the parental genes. Additionally, interaction networks between circRNA and 5 putative microRNA (miRNA) partners were constructed.

Results

Finally, 411 differentially expressed circRNAs were discovered, including 266 downregulated and 145 upregulated circRNAs. Compared with the control group, the expression level of hsa (Homo sapiens) _circ_0005360 (LDLR) and hsa_circ_0002168 (TMEM189) were proved significantly lower in the AAA group by qRT-PCR. Regarding upregulated circRNAs, the most enriched GO molecular function, biological process and cellular component terms were poly(A) RNA binding, negative regulation of transcription from RNA polymerase II promoter and nucleoplasm, respectively. Moreover, circRNA/miRNA interaction networks showed that hsa_circ_0005360/miR-181b and hsa_circ_0002168/miR-15a axis might have a regulative role in human AAA.

Conclusions

This study revealed new circRNAs potentially related to the pathogenesis of AAA. Further experimental studies are warranted to clarify the potential molecular mechanisms.

Selective and marked decrease of complement receptor C5aR2 in human thoracic aortic aneurysms: a dysregulation with potential inflammatory effects

Objective

The aetiology of thoracic aortic aneurysm (TAA) is largely unknown, but inflammation is likely to play a central role in the pathogenesis. In this present study, we aim to investigate the complement receptors in TAA.

Methods

Aortic tissue and blood from 31 patients with non-syndromic TAA undergoing thoracic aortic repair surgery were collected. Aortic tissue and blood from 36 patients with atherosclerosis undergoing coronary artery bypass surgery or aortic valve replacement were collected and served as control material. The expression of the complement anaphylatoxin receptors C3aR1, C5aR1 and C5aR2 in aortic tissue were examined by quantitative RT-PCR and C5aR2 protein by immunohistochemistry. Colocalisation of C5aR2 to different cell types was analysed by immunofluorescence. Complement activation products C3bc and sC5b-9 were measured in plasma.

Results

Compared with controls, TAA patients had substantial (73%) downregulated gene expression of C5aR2 as seen both at the mRNA (p=0.005) level and protein (p=0.03) level. In contrast, there were no differences in the expression of C3aR1 and C5aR1 between the two groups. Immunofluorescence examination showed that C5aR2 was colocalised to macrophages and T cells in the aortic media. There were no differences in the degree of systemic complement activation between the two groups.

Conclusion

Our findings suggest downregulation of the C5aR2, regarded to act mainly anti-inflammatory, in electively operated TAA as compared with non-aneurysmatic aortas of patients with aortic stenosis and/or coronary artery disease. This may tip the balance towards a relative increase in the inflammatory responses induced by C5aR1 and thus enhance the inflammatory processes in TAA.

The Prevalence of Nonalcoholic Fatty Pancreas by Endoscopic Ultrasonography

OBJECTIVES

Pancreatic steatosis or fatty pancreas refers to the fat accumulation in the pancreas, which can lead to inflammation and fibrosis, β-cell dysfunction, fibrosis, and, possibly, pancreatic cancer. This study aimed to study the prevalence of fatty pancreas and its risk factors in patients referred to an endosonography center.

METHODS

During 18 months, 228 patients who were referred to our endosonography center for various reasons were evaluated for fatty pancreas. Fatty pancreas was defined as hyperechoic pancreas echotexture compared with spleen echotexture. Demographic characteristics, past medical history, and laboratory measurements were compared between groups with and without fatty pancreas to determine the risk factors for fatty pancreas.

RESULTS

The prevalence of fatty pancreas was 25.9%. Patients with fatty pancreas had a significantly higher mean level of uric acid (P = 0.04), frequency of ischemic heart disease (P = 0.03), hyperlipidemia (P = 0.04), frequency of fatty liver (P < 0.001), and aortic intima thickness (P = 0.01). There was no significant difference in age, sex, body mass index, smoking status, substance abuse, and use of oral contraceptives in the 2 groups.

CONCLUSIONS

Fatty pancreas is a common disorder. There are meaningful relationships between coronary artery disease, nonalcoholic fatty liver, and atherosclerosis with fatty pancreas.

Tamsulosin attenuates abdominal aortic aneurysm growth

BACKGROUND

Tamsulosin, an α1A-adrenergic receptor inhibitor, is prescribed to treat benign prostatic hyperplasia in men >60 years of age, the same demographic most susceptible to abdominal aortic aneurysm. The goal of this study was to investigate the effect of tamsulosin on abdominal aortic aneurysm pathogenesis.

METHODS

Abdominal aortic aneurysms were induced in WT C57BL/6 male mice (n = 9-18/group), using an established topical elastase abdominal aortic aneurysm model. Osmotic pumps were implanted in mice 5 days before operation to create the model, administering either low dose (0.125 µg/day tamsulosin), high dose (0.250µg/day tamsulosin), or vehicle treatments with and without topical application of elastase. Blood pressures were measured preoperatively and on postoperative days 0, 3, 7, and 14. On postoperative day 14, aortic diameter was measured before harvest. Sample aortas were prepared for histology and cytokine analysis.

RESULTS

Measurements of systolic blood pressure did not differ between groups. Mice treated with the low dose of tamsulosin and with the high dose of tamsulosin showed decreased aortic diameter compared with vehicle-treated control (93% ± 24 versus 94% ± 30 versus 132% ± 24, respectively; P = .0003, P = .0003). Cytokine analysis demonstrated downregulation of pro-inflammatory cytokines in both treatment groups compared with the control (P < .05). Histology exhibited preservation of elastin in both low- and high-dose tamsulosin-treated groups (P = .0041 and P = .0018, respectively).

CONCLUSION

Tamsulosin attenuates abdominal aortic aneurysm formation with increased preservation of elastin and decreased production of pro-inflammatory cytokines. Further studies are necessary to elucidate the mechanism by which tamsulosin attenuates abdominal aortic aneurysm pathogenesis.

Association of high sensitivity C-reactive protein and abdominal aortic aneurysm: a meta-analysis and systematic review

OBJECTIVE

To evaluate the association of high sensitivity C-reactive protein (hsCRP) with the presence of abdominal aortic aneurysm (AAA).

METHODS

Medline, Cochrane, Embase, and Google Scholar databases were searched until 22 June 2016 using the keywords predictive factors, biomarkers, abdominal aortic aneurysm, prediction, high sensitivity C-reactive protein, and hsCRP. Prospective studies, retrospective studies, and cohort studies were included.

RESULTS

Twelve case-control studies were included in the meta-analysis with a total of 8345 patients (1977 in the AAA group and 6368 in the control group). The pooled results showed that AAA patients had higher hsCRP value than the control group (difference in means = 1.827, 95% CI = 0.010 to 3.645, p = .049). Subgroup analysis found AAA patients with medium or small aortic diameter (<50 mm) had higher hsCRP plasma levels than the control group (difference in means = 1.301, 95% CI = 0.821 to 1.781, p < .001). In patients with large aortic diameter (≥50 mm), no difference was observed in hsCRP levels between the AAA and control groups (difference in means = 1.769, 95% CI = -1.387 to 4.925, p = .272). Multi-regression analysis found the difference in means of hsCRP plasma levels between AAA and control groups decreased as aortic diameter increased (slope = -0.04, p < .001), suggesting that hsCRP levels may be inversely associated with increasing aneurysm size.

CONCLUSIONS

Our findings suggest that hsCRP levels may possibly be used as a diagnostic biomarker for AAA patients with medium or small aortic diameter but not for AAA patients with large aortic diameter. The correlation between serum hsCRP level and AAA aneurysm is not conclusive due to the small number of included articles and between-study heterogeneity.

Predictors Associated With Increased Prevalence of Abdominal Aortic Aneurysm in Chinese Patients with Atherosclerotic Risk Factors

OBJECTIVE/BACKGROUND

Epidemiological screening studies have demonstrated that the prevalence of abdominal aortic aneurysm (AAA) of Asian origin appears to be low and so increases uncertainty about the cost effectiveness of screening for AAAs in Chinese people. Some studies have demonstrated a higher prevalence of AAA in patients with atherosclerotic risk factors. The purpose of the study was to determine the prevalence of AAA and to explore the high risk group of AAA in Chinese patients with atherosclerotic risk factors.

METHODS

From November 2014 to July 2015, a prospective observational study was conducted in Guangdong General Hospital. In total, 1582 consecutive patients with atherosclerotic risk factors and undergoing coronary angiography for suspected or known coronary artery disease were enrolled to be screened for AAA by abdominal aortic ultrasound. Because of inadequate ultrasound image quality, the analysis was based on the 1541 (97.4%) patients whose abdominal aortic ultrasound images were adequate.

RESULTS

The prevalence of AAA was 1.6% in the whole study population and 2.9% in male patients aged over 65 years. In multivariate analysis, age ≥ 65 years (p = .029), smoking (p = .037), hypertension (p = .026), and aortic root diameter > 30 mm (p = .003) were independent predictors of AAA. The prevalence of AAA was 0% (0/153) in patients without any independent predictor, 0.6% (3/502) in patients with one predictor, 1.0% (6/597) in patients with two predictors, 4.8% (12/249) in patients with three predictors, and up to 10% (4/40) in patients with four predictors (p<.001; p value for trend < .001).

CONCLUSION

Age ≥ 65 years, smoking, hypertension, and aortic root diameter > 30 mm emerged as independent predictors of AAA in Chinese patients. Stepwise increases in the prevalence of AAA were found to depend on the number of independent predictors. Ultrasound screening for AAA could be considered in these high risk patients, especially those with three or four predictors.

Abdominal aortic aneurysm-an independent disease to atherosclerosis?

Atherosclerosis and abdominal aortic aneurysms (AAAs) are multifactorial and polygenic diseases with known environmental and genetic risk factors that contribute toward disease development. Atherosclerosis represents an important independent risk factor for AAA, as people with AAA often have atherosclerosis. Studies have shown that comorbidity is usually between ~25% and 55%, but it is still not fully known whether this association is causal or a result of common shared risk profiles. Most recent epidemiological, clinical, and biological evidence suggests that the two pathologies are more distinct than traditionally thought. For instance diabetes mellitus, hypercholesterolemia, and obesity are high risk for atherosclerosis development but are not as pronounced in AAA, whereas smoking, gender, and ethnicity are particularly high risk for AAA but less so for atherosclerosis. In addition, genetic and epigenetic studies have identified independent risk loci involved in AAA susceptibility that are not associated with other cardiovascular diseases, and research on important common cardiovascular biomarkers has illustrated discrepancies in those with AAA.

Periadventitial adipose-derived stem cell treatment halts elastase-induced abdominal aortic aneurysm progression

AIM

Demonstrate that periadventitial delivery of adipose-derived mesenchymal stem cells (ADMSCs) slows aneurysm progression in an established murine elastase-perfusion model of abdominal aortic aneurysm (AAA).

MATERIALS & METHODS

AAAs were induced in C57BL/6 mice using porcine elastase. During elastase perfusion, a delivery device consisting of a subcutaneous port, tubing and porous scaffold was implanted. Five days after elastase perfusion, 100,000 ADMSCs were delivered through the port to the aorta. After sacrifice at day 14, analyzed metrics included aortic diameter and structure of aortic elastin.

RESULTS

ADMSC treated aneurysms had a smaller diameter and less fragmented elastin versus saline controls.

CONCLUSION

Periadventitial stem cell delivery prevented the expansion of an established aneurysm between days 5 and 14 after elastase perfusion.

Abdominal Aortic Diameter and the Risk for Asymptomatic Peripheral Arterial Disease in Patients with Type 2 Diabetes

Peripheral arterial disease (PAD) is common among older people because it often results from atherosclerosis, which becomes more common with age. The disease is particularly common among people who have diabetes. Little information is available on the relation between abdominal aortic diameter and PAD in elderly patients with diabetes. This article studies the relationships between abdominal aortic diameter, PAD, and the cardiovascular risk factors in asymptomatic elderly patients suffering from type 2 diabetes mellitus. A case-control study was conducted on 90 participants aged 60 years and older divided into 60 cases (30 males and 30 females) and 30 age-matched healthy controls (15 males and 15 females). The relationships between the size of the abdominal aorta and ankle-brachial index (ABI), plasma cholesterol, triglycerides (TG), and high-sensitivity C-reactive protein were examined. Approximately, 15% of patients with diabetes had asymptomatic PAD. The patients with diabetes with PAD were of older age (70.4 ± 3.6 vs. 63.4 ± 3.9 years; p = 0.000), had larger abdominal aortic diameter (22.4 ± 3.08 vs. 18.7 ± 2 mm; p = 0.000), and higher CRP levels (8.3 ± 1.1 vs. 5.8 ± 2.2 mg/L; p = 0.002), while other variables revealed no significant difference. Abdominal aortic diameter correlated well with ABI measured by Doppler method in diabetic patients (r =  - 0.471, p = 0.000). Older age and larger abdominal aorta are independent risk factors for asymptomatic PAD in the elderly with type 2 diabetes mellitus.

Population risk factor estimates for abdominal aortic aneurysm from electronic medical records: a case control study

BACKGROUND

Using abdominal aortic aneurysm (AAA) as a model, this case-control study used electronic medical record (EMR) data to assess known risk factors and identify new associations.

METHODS

The study population consisted of cases with AAA (n =888) and controls (n =10,523) from the Geisinger Health System EMR in Central and Northeastern Pennsylvania. We extracted all clinical and diagnostic data for these patients from January 2004 to December 2009 from the EMR. From this sample set, bootstrap replication procedures were used to randomly generate 2,500 iterations of data sets, each with 500 cases and 2000 controls. Estimates of risk factor effect sizes were obtained by stepwise logistic regression followed by bootstrap aggregation. Variables were ranked using the number of inclusions in iterations and P values.

RESULTS

The benign neoplasm diagnosis was negatively associated with AAA, a novel finding. Similarly, type 2 diabetes, diastolic blood pressure, weight and myelogenous neoplasms were negatively associated with AAA. Peripheral artery disease, smoking, age, coronary stenosis, systolic blood pressure, age, height, male sex, pulmonary disease and hypertension were associated with an increased risk for AAA.

CONCLUSIONS

This study utilized EMR data, retrospectively, for risk factor assessment of a complex disease. Known risk factors for AAA were replicated in magnitude and direction. A novel negative association of benign neoplasms was identified. EMRs allow researchers to rapidly and inexpensively use clinical data to expand cohort size and derive better risk estimates for AAA as well as other complex diseases.

Prevalence and severity of asymptomatic coronary and carotid artery disease in patients with abdominal aortic aneurysm

We evaluated the prevalence and severity of occult coronary artery disease (CAD) and cerebrovascular disease (CeVD) in patients with abdominal aortic aneurysm (AAA). We studied 100 consecutive patients with no history of CAD, normal electrocardiogram, normal systolic function, and no angina or dyspnea. All patients underwent carotid Doppler study and invasive coronary angiography. Significant CAD was observed in 61% of patients. In all, 51% of patients with significant CAD showed either left main (n = 7), 3-vessel (n = 17), or proximal left anterior descending (n = 7) CAD, corresponding to 31% of the total cohort. Cerebrovascular disease was detected in 53% of patients, and in 38% of them was significant (peak systolic flow velocity ≥125 <230 cm/s). In 36% of patients with CeVD either left main (n = 5), 3-vessel (n = 11), or proximal left anterior descending (n = 3) CAD was observed. Severe asymptomatic CAD is prevalent in AAA, and 31% of patients fulfill indications for coronary revascularization.

Visceral adiposity is not associated with abdominal aortic aneurysm presence and growth

Previous studies in rodent models and patients suggest that visceral adipose could play a direct role in the development and progression of abdominal aortic aneurysm (AAA). This study aimed to assess the association of visceral adiposity with AAA presence and growth. This study was a case-control investigation of patients that did (n=196) and did not (n=181) have an AAA who presented to The Townsville Hospital vascular clinic between 2003 and 2012. Cases were patients with AAA (infra-renal aortic diameter >30 mm) and controls were patients with intermittent claudication but no AAA (infra-renal aortic diameter <30 mm). All patients underwent computed tomography angiography (CTA). The visceral to total abdominal adipose volume ratio was estimated from CTAs by assessing total and visceral adipose deposits using an imaging software program. Measurements were assessed for reproducibility by repeat assessments on 15 patients. AAA risk factors were recorded at entry. Forty-five cases underwent two CTAs more than 6 months apart to assess AAA expansion. The association of visceral adiposity with AAA presence and growth was examined using logistic regression. Visceral adipose assessment by CTA was highly reproducible (mean coefficient of variation 1.0%). AAA was positively associated with older age and negatively associated with diabetes. The visceral to total abdominal adipose volume ratio was not significantly associated with AAA after adjustment for other risk factors. Patients with a visceral to total abdominal adipose volume ratio in quartile four had a 1.63-fold increased risk of AAA but with wide confidence intervals (95% CI 0.71-3.70; p=0.248). Visceral adiposity was not associated with AAA growth. In conclusion, this study suggests that visceral adiposity is not specifically associated with AAA presence or growth although larger studies are required to confirm these findings.

Abdominal aortic aneurysms and coronary artery disease in a small country with high cardiovascular burden

We aimed to evaluate the frequency, clinical profiles and outcomes of abdominal aortic aneurysms (AAA), and their association with coronary artery disease (CAD) in a small country with high cardiovascular burden. Methods. Data were collected for all adult patients who underwent abdominal computed tomography scans at Hamad General Hospital in Qatar between 2004 and 2008. Results. Out of 13,115 screened patients for various reasons, 61 patients (0.5%) had abdominal aneurysms. The majority of AAA patients were male (82%) with a mean age of 67 ± 12 years. The incidence of AAA substantially increased with age reaching up to 5% in patients >80 yrs. Hypertension was the most prevalent risk factor for AAA followed by smoking, dyslipidemia, renal impairment, and diabetes mellitus. CAD and peripheral arterial disease (PAD) were observed in 36% and 13% of AAA patients, respectively. There were no significant correlations between CAD or PAD and site and size of AAA. Conclusion. This is the largest study in our region that describes the epidemiology of AAA with concomitant CAD. As the mortality rate is quite high in this high risk population, routine screening for AAA in CAD patients and vice versa needs further studies for proper risk stratification.

Risk factors in abdominal aortic aneurysm and in Polish population aortoiliac occlusive disease and differences between them [corrected]

Abdominal aortic aneurysm (AAA) and aortoiliac occlusive disease (AIOD) are multifactorial vascular disorders caused by complex genetic and environmental factors. The purpose of this study was to define risk factors of AAA and AIOD in the Polish population and indicate differences between diseases.

Aortic aneurysm disease vs. aortic occlusive disease: differences in outcome and intensive care resource utilisation after elective surgery: an observational study

CONTEXT

Abdominal aortic surgery is a high-risk procedure, with aortic aneurysm and aortic occlusive diseases being the main indications. These groups are often regarded as having equal perioperative risk profiles. Previous reports suggest that the haemodynamic and inflammatory response to aortic clamping is more pronounced in patients with aortic aneurysm disease, which may affect outcome.

OBJECTIVES

The aim of this observational cohort study was to evaluate outcome after open elective abdominal aortic surgery, hypothesising a higher 30-day mortality, a higher incidence of postoperative organ dysfunction and a longer length of stay in patients with aortic aneurysm compared with aortic occlusive disease.

DESIGN

Cohort observational study based on prospective registrations from national databases.

SETTING

Eight Danish hospitals, including four university and four non-university centres, from 1 January 2007 to 1 March 2010.

PATIENTS

One thousand two hundred and ninety-three patients scheduled for primary open elective, aortoiliac bypass or aortofemoral bypass procedures or abdominal aortic aneurysm repair.

MAIN OUTCOME MEASURES

Mechanical ventilation, acute dialysis, use of vasopressors or inotropes, ICU stay more than 24 h, hospital length of stay and mortality.

RESULTS

Compared with aortic occlusive disease, more patients with aortic aneurysm disease had ICU stays more than 24 h (62 vs. 45%, P < 0.001) and more often needed acute dialysis or ventilatory support (17 vs. 11%, P = 0.04). No difference was found in hospital length of stay, 30-day mortality or overall risk of death. Mortality after 1 year was higher in patients with aortic aneurysm disease (8 vs. 4.7%, P = 0.04).

CONCLUSION

Patients with abdominal aortic aneurysms were at higher risk of developing postoperative organ dysfunction and required more ICU resources than patients with occlusive disease, despite no differences in hospital length of stay or 30-day mortality. Distinguishing between these two diseases may be useful in planning and distribution of ICU resources and for in future studies.

Analysis of the molecular mobility of collagen and elastin in safe, atheromatous and aneurysmal aortas

AIM OF THE STUDY

In this study, we propose to use a thermal technique, Differential Scanning Calorimetry (DSC) to follow the evolution of elastin and collagen in safe and pathological cardiovascular tissues.

PATIENTS AND METHODS

The first part of this study deals with the analysis of the elastin network and associated proteins during ageing (from children to old persons) in aortic walls. The second part is devoted to the characterization of the collagenic phase in aneurysms. In both cases, physical data are correlated with biochemical analyses.

RESULTS AND CONCLUSION

For old persons aortas with atheromatous stades, elastin and associated proteins are found to interpenetrate to form a homogenous phase. Abdominal aortic aneurysms (AAA) are characterized by structural alterations of the aortic wall resulting from the degradation of elastic fibers and an increase of collagen/elastin ratio. Notable modifications are evidenced between collagen from control tissue and collagen from AAA, particularly concerning the thermal denaturation. Biochemical and thermal results are compatible with the increase of new collagen deposition and/or impairment of the collagen phase stability in the extracellular matrix of AAAs.

Cigarette smoke enhances abdominal aortic aneurysm formation in angiotensin II-treated apolipoprotein E-deficient mice

Cigarette smoke, hyperlipidemia, and hypertension with the risk of development and progression of atherosclerosis and associated pathologies such as abdominal aortic aneurysm (AAA) are correlated. We examined the interaction of cigarette mainstream smoke (MS) and angiotensin-II (Ang II)-induced hypertension in the atherosclerotic process using hyperlipidemic apolipoprotein E-knockout (ApoE(-/-)) mice. ApoE(-/-) mice were treated with Ang II for 4 weeks and then further exposed to MS or to fresh air for 4 weeks. AAA formation was observed in all mice treated with Ang II, regardless of smoke exposure; however, smoke exposure increased the incidence of AAA in these mice. Ang II treatment resulted in higher gene expression of matrix metalloproteinases (MMP)-2, -3, -8, -9, and -12 in the abdominal aortas, which was further increased by MS exposure. The proteolytic activity of MMP-2 and MMP-9 was also enhanced in Ang II-treated mice exposed to MS, but only minor changes were seen with either smoke exposure or Ang II treatment alone. This study shows for the first time that both formation and severity of AAA in hypertensive ApoE(-/-) mice are accelerated by exposure to MS and that the proteolytic activity of MMPs is enhanced by the combination of Ang II and MS.

Pathophysiology and epidemiology of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are found in up to 8% of men aged >65 years, yet usually remain asymptomatic until they rupture. Rupture of an AAA and its associated catastrophic physiological insult carries overall mortality in excess of 80%, and 2% of all deaths are AAA-related. Pathologically, AAAs are associated with inflammation, smooth muscle cell apoptosis, and matrix degradation. Once thought to be a consequence of advanced atherosclerosis, accruing evidence indicates that AAAs are a focal representation of a systemic disease of the vasculature. Risk factors for AAAs include increasing age, male sex, smoking, and low HDL-cholesterol levels. Familial associations exist and although susceptibility genes have been described on the basis of candidate-gene studies, robust genetic studies have failed to discover causative gene mutations. The surgical management of AAAs has been revolutionized by minimally invasive endovascular repair. Ongoing randomized trials will establish whether endovascular repair confers a survival advantage over open surgery for patients with a ruptured AAA. In many countries, centralization of vascular surgical services has largely been driven by the improved outcomes of elective aneurysm surgery in specialized centers, the widespread adoption of endovascular techniques, and the introduction of screening programs.

Atherosclerosis in abdominal aortic aneurysms: a causal event or a process running in parallel? The Tromsø study

OBJECTIVE

The pathogenesis of abdominal aortic aneurysm (AAA) formation is poorly understood. We investigated the relationship between carotid, femoral, and coronary atherosclerosis and abdominal aortic diameter, and whether atherosclerosis was a risk marker for AAA.

METHODS AND RESULTS

Ultrasound of the right carotid artery, the common femoral artery, and the abdominal aorta was performed in 6446 men and women from a general population. The burden of atherosclerosis was assessed as carotid total plaque area, common femoral lumen diameter, and self-reported coronary heart disease. An AAA was defined as maximal infrarenal aortic diameter > or =30 mm. No dose-response relationship was found between carotid atherosclerosis and abdominal aortic diameter <27 mm. However, significantly more atherosclerosis and coronary heart disease was found in aortic diameter > or =27 mm and in AAAs. The age- and sex-adjusted odds ratio (OR) (95% CI) for AAA in the top total plaque area quintile was 2.3 (1.5 to 3.4), as compared with subjects without plaques. The adjusted OR (95% CI) was 1.7 (1.1 to 2.6). No independent association was found between femoral lumen diameter and AAA.

CONCLUSIONS

The lack of a consistent dose-response relationship between atherosclerosis and abdominal aortic diameter suggests that atherosclerosis may not be a causal event in AAA but develops in parallel with or secondary to aneurismal dilatation.

Extracellular matrix molecules: potential targets in pharmacotherapy

The extracellular matrix (ECM) consists of numerous macromolecules classified traditionally into collagens, elastin, and microfibrillar proteins, proteoglycans including hyaluronan, and noncollagenous glycoproteins. In addition to being necessary structural components, ECM molecules exhibit important functional roles in the control of key cellular events such as adhesion, migration, proliferation, differentiation, and survival. Any structural inherited or acquired defect and/or metabolic disturbance in the ECM may cause cellular and tissue alterations that can lead to the development or progression of disease. Consequently, ECM molecules are important targets for pharmacotherapy. Specific agents that prevent the excess accumulation of ECM molecules in the vascular system, liver, kidney, skin, and lung; alternatively, agents that inhibit the degradation of the ECM in degenerative diseases such as osteoarthritis would be clinically beneficial. Unfortunately, until recently, the ECM in drug discovery has been largely ignored. However, several of today's drugs that act on various primary targets affect the ECM as a byproduct of the drugs' actions, and this activity may in part be beneficial to the drugs' disease-modifying properties. In the future, agents and compounds targeting directly the ECM will significantly advance the treatment of various human diseases, even those for which efficient therapies are not yet available.

Review of Current Theories for Abdominal Aortic Aneurysm Pathogenesis

Atherosclerotic plaques are a feature of abdominal aortic aneurysms (AAAs). Atherosclerosis and AAA appear to share similar risk factors. These observations have led to the conclusion that AAAs are a consequence of advanced atherosclerosis.

This review explores current theories regarding the pathogenesis of AAA and their implications for treatment.

A systematic literature search was conducted using the search terms abdominal aortic aneurysm, atherosclerosis, pathogenesis, and systemic disease. Articles were categorized according to the association of AAAs with atherosclerosis, arteriomegaly, peripheral aneurysm, systemic expression, genetics, autoimmunity, oxidative stress, and systemic disease. Twenty-nine articles reporting changes in the systemic vasculature associated with AAA and 12 articles examining the shared risk factor hypothesis were identified.

There is insufficient evidence to confirm that AAAs are the result of advanced atherosclerosis. The bulk of evidence points to AAA disease being a systemic disease of the vasculature, with a predetermined genetic susceptibility leading to a phenotype governed by environmental factors.