Are aortic aneurysms caused by atherosclerosis?

Tobacco smoking and the risk of aortic dissection in the UK Biobank and a meta-analysis of prospective studies

Tobacco smoking is thought to increase risk of aortic dissection, however, few prospective studies have been published on the association to date and little is known about the effect of smoking cessation on risk of aortic dissection. To clarify these associations we investigated the association between different aspects of tobacco smoking and aortic dissection in the UK Biobank Study and we summarized the available data in a meta-analysis of cohort studies. Multivariable Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between smoking and risk of aortic dissection in the UK Biobank. PubMed and Embase were searched up to 19th of July 2024 to identify relevant cohort studies and random effects models were used to calculate summary relative risks (RRs) and 95% CIs in the meta-analysis. During a mean follow-up of 12.3 years a total of 376 incident cases of aortic dissection were identified among 499,078 participants. The multivariable adjusted hazard ratio for current and former smokers versus never smokers were 2.48 (1.87-3.29) and 1.03 (0.81-1.29), respectively. There was a dose-response between increasing number of cigarettes smoked per day and aortic dissection risk with HRs (95% CIs) of 2.31 (1.13-4.71), 2.94 (1.88-4.58), and 2.63 (1.65-4.37) for 1-9, 10-19, and ≥ 20 cigarettes/day among current smokers. Greater number of pack-years was positively associated with aortic dissection (1.66, 1.21-2.28 for ≥ 30 pack-years vs. never smokers). Former smokers who had quit for varying durations had a 48-75% reduction in aortic dissection risk when compared to current smokers. In the meta-analysis, the summary RR was 2.44 (1.65-3.60, I2 = 68%, n = 3) for current and 1.32 (0.72-2.40, I2 = 75%, n = 3) for former vs. never smokers, 1.52 (1.30-1.79, I2 = 31%, n = 3) per 10 cigarettes/day, 1.16 (1.06-1.28, I2 = 44%, n = 3) per 10 pack-years, and 0.78 (0.71-0.86, I2 = 0%, n = 2) per 10 years since quitting smoking. These results provide further support that tobacco smoking increases the risk of developing aortic dissection with some indication of a dose-response with increasing intensity and amount, while smoking cessation attenuated this risk. Although further studies are needed, these findings provide further support for policies to reduce the prevalence of smoking in the general population and to promote smoking cessation among smokers.

Exploring Disparities in Atherosclerosis Comorbidity with Aortic Aneurysm

Aortic aneurysm (AA) and atherosclerosis (AS) of various vascular beds are asymptomatic for a long time and are relatively common pathological conditions that lead to life-threatening and disabling complications. In this review, we discuss the current understanding of the high variation in direct and inverse comorbidity of AA and AS as presented in scientific publications. Estimates of AA and AS comorbidity depend on several factors, such as the location of AA (ascending or descending thoracic aorta or abdominal aorta), familial or sporadic cases of AA, syndromic forms of AA, and/or aortic valve pathology (bicuspid aortic valve [BAV]). To identify the causes of the comorbidity of AA and AS, it is important to consider and characterise many factors in detail. These factors include clinical characteristics of the patients included in a study (age, sex) and risk factors (mainly the presence of monogenic forms and BAV, hypertension, hypercholesterolaemia, diabetes mellitus, and cigarette smoking). Additionally, it is essential to consider characteristics of the disease course and the nature of multimorbidity and to take into account pathologies not only of the cardiovascular system but also of other organ systems, with special attention to metabolic and endocrine disorders.

Elevated High Sensitivity C Reactive Protein and Risk of Abdominal Aortic Aneurysm: A Prospective Population Based Study in The Norwegian HUNT Study

OBJECTIVE

Inflammation seems to be crucial in the pathogenesis of abdominal aortic aneurysm (AAA). Previous research links inflammatory biomarkers, such as high sensitivity C reactive protein (hs-CRP), to AAA. Few studies, however, have used a prospective design. The aim of this study was to examine whether individuals with elevated hs-CRP have increased risk of AAA, using a prospective and population based design.

METHODS

This prospective, population based, cohort study included 46 322 participants in the Trøndelag Health Study (HUNT) in Norway (53.7% female). During a median follow up of 12.6 years (range 0 - 26 years), 407 individuals were diagnosed with AAA (22.4% female). Cox proportional hazards regression was applied to examine associations between hs-CRP and risk of AAA. hs-CRP was treated either as a continuous or a categorical variable (dichotomised at 2 mg/L, 1 mg/L, or median [1.2 mg/L], or as quartiles).

RESULTS

The hazard ratio (HR) of developing AAA per 1 mg/L increase in hs-CRP (continuous hs-CRP) was 1.02 (95% confidence interval [CI] 1.01 - 1.03) in the analysis adjusted for smoking, coronary heart disease, hypertension, diabetes, body mass index, and total cholesterol. Individuals with hs-CRP ≥ 2 mg/L had almost twice the risk of AAA compared with individuals with hs-CRP < 2 mg/L (adjusted HR 1.84, 95% CI 1.51 - 2.25). Dichotomising hs-CRP at a clinical cutoff point of 1 mg/L (adjusted HR 2.13, 95% CI 1.64 -2.76) or at the median of 1.2 mg/L (adjusted HR 2.12, 95% CI 1.62 - 2.76) slightly strengthened the HR. The adjusted HR gradually increased through the ordered hs-CRP quartiles, and was almost four times higher (HR 3.87, 95% CI 2.54 - 5.92) in the highest hs-CRP quartile (hs-CRP > 2.7 mg/L) compared with the lowest quartile (hs-CRP ≤ 0.6 mg/L).

CONCLUSION

Individuals with elevated hs-CRP had significantly increased risk of developing AAA.

The rejection that defies antirejection drugs-chronic vascular rejection (allograft vasculopathy): The role of terminology and linguistic relativity

While allograft loss due to acute rejection has been dramatically reduced due to the introduction of immunophilins, this therapy has little effect on allografts lost due to chronic vascular rejection. This situation may be due to a misnomer of the pathology. Specifically, its designation as 'chronic rejection' has given the wrong impression that the cause of the disease has been identified. Analyzing this phenomenon under the rubric of linguistic relativity suggests that the words chosen to name the disease may have restricted our cognitive ability to solve the problem. Thus, we have to step out of the 'alloimmunity/rejection box'. Let's pause between our words, Speak and fall silent again, So that the meaning of the word just spoken, Sounds a clearer echo in our heads. Let's pause between our words. Andrey Makarevich.

A comprehensive MRI-based computational model of blood flow in compliant aorta using radial basis function interpolation

BACKGROUND

Properly understanding the origin and progression of the thoracic aortic aneurysm (TAA) can help prevent its growth and rupture. For a better understanding of this pathogenesis, the aortic blood flow has to be studied and interpreted in great detail. We can obtain detailed aortic blood flow information using magnetic resonance imaging (MRI) based computational fluid dynamics (CFD) with a prescribed motion of the aortic wall.

METHODS

We performed two different types of simulations-static (rigid wall) and dynamic (moving wall) for healthy control and a patient with a TAA. For the latter, we have developed a novel morphing approach based on the radial basis function (RBF) interpolation of the segmented 4D-flow MRI geometries at different time instants. Additionally, we have applied reconstructed 4D-flow MRI velocity profiles at the inlet with an automatic registration protocol.

RESULTS

The simulated RBF-based movement of the aorta matched well with the original 4D-flow MRI geometries. The wall movement was most dominant in the ascending aorta, accompanied by the highest variation of the blood flow patterns. The resulting data indicated significant differences between the dynamic and static simulations, with a relative difference for the patient of 7.47±14.18% in time-averaged wall shear stress and 15.97±43.32% in the oscillatory shear index (for the whole domain).

CONCLUSIONS

In conclusion, the RBF-based morphing approach proved to be numerically accurate and computationally efficient in capturing complex kinematics of the aorta, as validated by 4D-flow MRI. We recommend this approach for future use in MRI-based CFD simulations in broad population studies. Performing these would bring a better understanding of the onset and growth of TAA.

Integrins as Drug Targets in Vascular and Related Diseases

Integrins are transmembrane receptors that, as critical participants in a vast range of pathological processes, are potential therapeutic targets. However, in only a few cases has the promise been realized by drug approval. In this review, we briefly review basic integrin biology and participation in disease, challenges in the development of safe, effective integrin-targeted therapies, and recent advances that may lead to progress.

Animal Models, Pathogenesis, and Potential Treatment of Thoracic Aortic Aneurysm

Thoracic aortic aneurysm (TAA) has a prevalence of 0.16-0.34% and an incidence of 7.6 per 100,000 person-years, accounting for 1-2% of all deaths in Western countries. Currently, no effective pharmacological therapies have been identified to slow TAA development and prevent TAA rupture. Large TAAs are treated with open surgical repair and less invasive thoracic endovascular aortic repair, both of which have high perioperative mortality risk. Therefore, there is an urgent medical need to identify the cellular and molecular mechanisms underlying TAA development and rupture to develop new therapies. In this review, we summarize animal TAA models including recent developments in porcine and zebrafish models: porcine models can assess new therapeutic devices or intervention strategies in a large mammal and zebrafish models can employ large-scale small-molecule suppressor screening in microwells. The second part of the review covers current views of TAA pathogenesis, derived from recent studies using these animal models, with a focus on the roles of the transforming growth factor-beta (TGFβ) pathway and the vascular smooth muscle cell (VSMC)-elastin-contractile unit. The last part discusses TAA treatment options as they emerge from recent preclinical studies.

Heat transfer mechanism in idealized healthy and diseased aortas using fluid-structure interaction method

The heat transfer mechanism inside the human aorta may be related to the physiological function and lesion formation of the aortic wall. The objective of this study was to acquire the temperature distribution in the three-dimensional idealized aorta. An idealized healthy aortic geometry and three representative diseased aortas: aortic aneurysm, coarctation of the aorta, and aortic dissection were constructed. Advanced fluid-structure interaction (FSI) computational framework was applied to predict the aortic temperature distribution. The movement of the aortic root due to the heartbeat was also considered. The displacement distribution of the aortic vessel wall was consistent with clinical observation. The lesser curvature of the aortic arch, aneurysm body, coarctation region, and false lumen were all exposed to relatively high temperatures (over 310.006 K). We found that the rigid wall assumption slightly underestimated the magnitude of the whole aortic wall-averaged temperature while the changing trend and local temperature were like the results of the FSI method. Besides, the wall-averaged temperature would increase and the temperature inflection point would advance when the aortic vessel wall was loaded with a high heat flux. This pilot study revealed the aortic heat transfer mechanism and temperature distribution, and the findings may help to understand the physiological characteristics of the aortic vessel wall.

The contribution of matrix metalloproteinases and their inhibitors to the development, progression, and rupture of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) account for up to 8% of deaths in men aged 65 years and over and 2.2% of women. Patients with AAAs often have atherosclerosis, and intimal atherosclerosis is generally present in AAAs. Accordingly, AAAs are considered a form of atherosclerosis and are frequently referred to as atherosclerotic aneurysms. Pathological observations advocate inflammatory cell infiltration alongside adverse extracellular matrix degradation as key contributing factors to the formation of human atherosclerotic AAAs. Therefore, macrophage production of proteolytic enzymes is deemed responsible for the damaging loss of ECM proteins, especially elastin and fibrillar collagens, which characterise AAA progression and rupture. Matrix metalloproteinases (MMPs) and their regulation by tissue inhibitors metalloproteinases (TIMPs) can orchestrate not only ECM remodelling, but also moderate the proliferation, migration, and apoptosis of resident aortic cells, alongside the recruitment and subsequent behaviour of inflammatory cells. Accordingly, MMPs are thought to play a central regulatory role in the development, progression, and eventual rupture of abdominal aortic aneurysms (AAAs). Together, clinical and animal studies have shed light on the complex and often diverse effects MMPs and TIMPs impart during the development of AAAs. This dichotomy is underlined from evidence utilising broad-spectrum MMP inhibition in animal models and clinical trials which have failed to provide consistent protection from AAA progression, although more encouraging results have been observed through deployment of selective inhibitors. This review provides a summary of the supporting evidence connecting the contribution of individual MMPs to AAA development, progression, and eventual rupture. Topics discussed include structural, functional, and cell-specific diversity of MMP members; evidence from animal models of AAA and comparisons with findings in humans; the dual role of MMPs and the requirement to selectively target individual MMPs; and the advances in identifying aberrant MMP activity. As evidenced, our developing understanding of the multifaceted roles individual MMPs perform during the progression and rupture of AAAs, should motivate clinical trials assessing the therapeutic potential of selective MMP inhibitors, which could restrict AAA-related morbidity and mortality worldwide.

Effect of aortic bifurcation geometry on pressure and peak wall stress in abdominal aorta: Fluid-structure interaction study

BACKGROUND AND OBJECTIVE

Geometry of aorto-iliac bifurcation may affect pressure and wall stress in aorta and thus potentially serve as a predictor of abdominal aortic aneurysm (AAA), similarly to hypertension.

METHODS

Effect of aorto-iliac bifurcation geometry was investigated via parametric analysis based on two-way weakly coupled fluid-structure interaction simulations. The arterial wall was modelled as isotropic hyperelastic monolayer, and non-Newtonian behaviour was introduced for the fluid. Realistic boundary conditions of the pulsatile blood flow were used on the basis of experiments in literature and their time shift was tailored to the pulse wave velocity in the model to obtain physiological wave shapes. Eighteen idealized and one patient-specific geometries of human aortic tree with common iliac and renal arteries were considered with different angles between abdominal aorta (AA) and both iliac arteries and different area ratios (AR) of iliac and aortic luminal cross sections.

RESULTS

Peak wall stress (PWS) and systolic blood pressure (SBP) were insensitive to the aorto-iliac angles but sensitive to the AR: when AR decreased by 50%, the PWS and SBP increased by up to 18.4% and 18.8%, respectively.

CONCLUSIONS

Lower AR (as a result of the iliac stenosis or aging), rather than the aorto-iliac angles increases the BP in the AA and may be thus a risk factor for the AAA development.

Status of diagnosis and therapy of abdominal aortic aneurysms

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

Genome-wide association study of thoracic aortic aneurysm and dissection in the Million Veteran Program

The current understanding of the genetic determinants of thoracic aortic aneurysms and dissections (TAAD) has largely been informed through studies of rare, Mendelian forms of disease. Here, we conducted a genome-wide association study (GWAS) of TAAD, testing ~25 million DNA sequence variants in 8,626 participants with and 453,043 participants without TAAD in the Million Veteran Program, with replication in an independent sample of 4,459 individuals with and 512,463 without TAAD from six cohorts. We identified 21 TAAD risk loci, 17 of which have not been previously reported. We leverage multiple downstream analytic methods to identify causal TAAD risk genes and cell types and provide human genetic evidence that TAAD is a non-atherosclerotic aortic disorder distinct from other forms of vascular disease. Our results demonstrate that the genetic architecture of TAAD mirrors that of other complex traits and that it is not solely inherited through protein-altering variants of large effect size.

The mechanism and therapy of aortic aneurysms

Aortic aneurysm is a chronic aortic disease affected by many factors. Although it is generally asymptomatic, it poses a significant threat to human life due to a high risk of rupture. Because of its strong concealment, it is difficult to diagnose the disease in the early stage. At present, there are no effective drugs for the treatment of aneurysms. Surgical intervention and endovascular treatment are the only therapies. Although current studies have discovered that inflammatory responses as well as the production and activation of various proteases promote aortic aneurysm, the specific mechanisms remain unclear. Researchers are further exploring the pathogenesis of aneurysms to find new targets for diagnosis and treatment. To better understand aortic aneurysm, this review elaborates on the discovery history of aortic aneurysm, main classification and clinical manifestations, related molecular mechanisms, clinical cohort studies and animal models, with the ultimate goal of providing insights into the treatment of this devastating disease. The underlying problem with aneurysm disease is weakening of the aortic wall, leading to progressive dilation. If not treated in time, the aortic aneurysm eventually ruptures. An aortic aneurysm is a local enlargement of an artery caused by a weakening of the aortic wall. The disease is usually asymptomatic but leads to high mortality due to the risk of artery rupture.

Conventional aortic root vs valve-sparing root replacement surgery in aortic dilatation syndromes: a comparison of mortality and postoperative complications

INTRODUCTION

Conventional aortic root and valve-sparing root replacement surgery are two current surgical treatments for aortic dilatation syndromes. This review article aims to review the current literature surrounding these two established techniques.

AREAS COVERED

This review article will address the current indications for valve-sparing root replacement surgery, technical considerations in surgical planning and a comparison of clinical outcomes between these two surgical techniques.

EXPERT OPINION

Valve-sparing root replacement surgery is a safe and established treatment for aortic syndromes. Valve-sparing surgery procedure avoids the inherent risk of prosthetic valve dysfunction and prosthesis infection by preserving the native aortic valve compared to conventional aortic root surgery. This has been demonstrated in various observational studies and should be considered in clinically and anatomically appropriate patients. Other technical considerations, such as reimplantation versus remodeling technique and aortic cusp repair in select patients, may impact in short-term procedural and long-term clinical success with valve-sparing surgery.

Augmentation Index in Patients with Thoracic Aortic Aneurysm: A Matched Case-Control Study

Thoracic aortic aneurysms (TAA) may be associated with complications such as rupture and dissection, which can lead to a fatal outcome. Increased central arterial stiffness has been proposed to be present in patients with TAA compared to unmatched controls. We aimed to assess whether wall properties in patients with TAA are also altered when compared to a matched control group. Applanation tonometry was performed in 74 adults with TAA and 74 sex, age, weight, height, and left ventricular ejection fraction matched controls. Subsequently analysis of the pulse wave was done using the SphygmoCor System. For comparing the two groups, AIx was adjusted to a heart rate of 75/min (AIx@75). 148 1-to-1 matched participants were included in the final model. There was no significant difference in the Alx@75 between the TAA group and the matched control group [mean (SD) of 24.7 (11.2) % and 22.8 (11.2) %, p = 0.240]. Adjusted for known cardiovascular risk factors, there was no association between TAA and AIx@75. Patients with TAA showed comparable arterial wall properties to cardiovascular risk factor matched controls. Since higher arterial stiffness is associated with TAA progression, it remains to be investigated if increased central arterial stiffness is a relevant factor of TAA emergence.

Thoracic and Thoracoabdominal Aneurysms: Etiology, Epidemiology, and Natural History

Thoracic aortic aneurysms and thoracoabdominal aneurysms are often found incidentally. Complications include dissection or rupture. Most of the thoracic aortic aneurysms and thoracoabdominal aneurysms develop in patients with risk factors for atherosclerosis. Younger patients without significant cardiovascular risk factors may have a genetic basis and include syndromes such as Marfan, Ehlers-Danlos, and Loeys-Dietz and bicuspid aortic valve. Most thoracic aneurysms grow slowly over time and factors that accelerate growth rate include dissection, aneurysm size, bicuspid valve disease, and Marfan syndrome. Size cutoffs where complications occur determine when surgery or intervention should be considered.

Human abdominal aortic aneurysm (AAA): Evidence for an autoimmune antigen-driven disease

Abdominal aortic aneurism (AAA) is a complex immunological disease with a strong genetic component, and one of the ten leading causes of death of individuals 55-74 years old worldwide. Strong evidence has been accumulated suggesting that AAA is an autoimmune specific antigen-driven disease. Mononuclear cells infiltrating AAA lesions comprised of T and B lymphocytes and other cells expressing early-, intermediate- and late-activation antigens, and the presence of antigen-presenting cells have been documented, demonstrating an ongoing immune response. The three components of the trimolecular complex, T-cell receptor (TCR)/peptide (antigen)/HLA have been identified in AAA, and specifically: (i) clonal expansions of T-cell clones in AAA lesions; (ii) the association of AAA with particular HLA Class I and Class II; and (iii) self or nonself putative AAA-associated antigens. IgG autoantibodies recognizing proteins present in normal aortic tissue have been reported in patients with AAA. Molecular mimicry, defined as the sharing of antigenic epitopes between microorganisms (bacteria, viruses) and self antigens, maybe is responsible for T-cell responses and antibody production in AAA. Also, the frequency and the suppressor activity of CD4 + CD25 + FOXP3+ Tregs and the expression of FOXP3 transcripts and protein have been reported to be significantly impaired in AAA patients vs normal donors.

Specialized Pro-Resolving Lipid Mediators: New Therapeutic Approaches for Vascular Remodeling

Vascular remodeling is a typical feature of vascular diseases, such as atherosclerosis, aneurysms or restenosis. Excessive inflammation is a key mechanism underlying vascular remodeling via the modulation of vascular fibrosis, phenotype and function. Recent evidence suggests that not only augmented inflammation but unresolved inflammation might also contribute to different aspects of vascular diseases. Resolution of inflammation is mediated by a family of specialized pro-resolving mediators (SPMs) that limit immune cell infiltration and initiate tissue repair mechanisms. SPMs (lipoxins, resolvins, protectins, maresins) are generated from essential polyunsaturated fatty acids. Synthases and receptors for SPMs were initially described in immune cells, but they are also present in endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), where they regulate processes important for vascular physiology, such as EC activation and VSMC phenotype. Evidence from genetic models targeting SPM pathways and pharmacological supplementation with SPMs have demonstrated that these mediators may play a protective role against the development of vascular remodeling in atherosclerosis, aneurysms and restenosis. This review focuses on the latest advances in understanding the role of SPMs in vascular cells and their therapeutic effects in the vascular remodeling associated with different cardiovascular diseases.

Blood Pressure, Hypertension, and the Risk of Aortic Dissection Incidence and Mortality: Results From the J-SCH Study, the UK Biobank Study, and a Meta-Analysis of Cohort Studies

BACKGROUND

Hypertension or elevated blood pressure (BP) is an important risk factor for aortic dissection (AD); however, few prospective studies on this topic have been published. We investigated the association between hypertension/elevated BP and AD in 2 cohorts and conducted a meta-analysis of published prospective studies, including these 2 studies.

METHODS

We analyzed data from the J-SHC study (Japan-Specific Health Checkups) and UK Biobank, which prospectively followed up 534 378 and 502 424 participants, respectively. Multivariable Cox regression was used to estimate hazard ratios and 95% CIs for the association of hypertension/elevated BP with AD incidence in the UK Biobank and AD mortality in the J-SHC Study. In the meta-analysis, summary relative risks were calculated with random-effects models. A potential nonlinear dose-response relationship between BP and AD was tested with fractional polynomial models, and the best-fitting second-order fractional polynomial regression model was determined.

RESULTS

In the J-SHC study and UK Biobank, there were 84 and 182 ADs during the 4- and 9-year follow-up, and the adjusted hazard ratios of AD were 3.57 (95% CI, 2.17-6.11) and 2.68 (95% CI, 1.78-4.04) in hypertensive individuals, 1.33 (95% CI, 1.05-1.68) and 1.27 (95% CI, 1.11-1.48) per 20-mm Hg increase in systolic BP (SBP), and 1.67 (95% CI, 1.40-2.00) and 1.66 (95% CI, 1.46-1.89) per 10-mm Hg increase in diastolic BP (DBP), respectively. In the meta-analysis, the summary relative risks were 3.07 (95% CI, 2.15-4.38, I2=76.7%, n=7 studies, 2818 ADs, 4 563 501 participants) for hypertension and 1.39 (95% CI, 1.16-1.66, I2=47.7%, n=3) and 1.79 (95% CI: 1.51-2.12, I2 = 57.0%, n=3) per 20-mm Hg increase in SBP and per 10-mm Hg increase in DBP, respectively. The AD risk showed a strong, positive dose-response relationship with SBP and even more so with DBP. The risk of AD in the nonlinear dose-response analysis was significant at SBP >132 mm Hg and DBP >75 mm Hg.

CONCLUSIONS

Hypertension and elevated SBP and DBP are associated with a high risk of AD. The risk of AD was positively dose dependent, even within the normal BP range. These findings provide further evidence for the optimization of BP to prevent AD.

Lysyl hydroxylase 1 (LH1) deficiency promotes angiotensin II (Ang II)-induced dissecting abdominal aortic aneurysm

Rationale: The progressive disruption of extracellular matrix (ECM) proteins, particularly early elastin fragmentation followed by abnormalities in collagen fibril organization, are key pathological processes that contribute to dissecting abdominal aortic aneurysm (AAA) pathogenesis. Lysyl hydroxylase 1 (LH1) is essential for type I/III collagen intermolecular crosslinking and stabilization. However, its function in dissecting AAA has not been explored. Here, we investigated whether LH1 is significantly implicated in dissecting AAA progression and therapeutic intervention. Methods and Results: Sixteen-week-old male LH1-deficient and wild-type (WT) mice on the C57Bl/6NCrl background were infused with angiotensin II (Ang II, 1000 ng/kg per minute) via subcutaneously implanted osmotic pumps for 4 weeks. Ang II increased LH1 levels in the abdominal aortas of WT mice, whereas mice lacking LH1 developed dissecting AAA. To evaluate the related mechanism, we performed whole-transcriptomic analysis, which demonstrated that LH1 deficiency aggravated gene transcription alterations; in particular, the expression of thrombospondin-1 was markedly upregulated in the aortas of LH1-deficient mice. Furthermore, targeting thrombospondin-1 with TAX2 strongly inhibited the proinflammatory process, matrix metalloproteinase (MMP) activity and vascular smooth muscle cells (VSMCs) apoptosis, ultimately decreasing the incidence of dissecting AAA. Restoration of LH1 protein expression in LH1-deficient mice by intraperitoneal injection of an adeno-associated virus normalized thrombospondin-1 levels, subsequently alleviating dissecting AAA formation and preserving aortic structure and function. Consistently, in human AAA specimens, decreased LH1 expression was associated with increased thrombospondin-1 levels. Conclusions: LH1 deficiency contributes to dissecting AAA pathogenesis, at least in part, by upregulating thrombospondin-1 expression, which subsequently enables proinflammatory processes, MMP activation and VSMCs apoptosis. Our study provides evidence that LH1 is a potential critical therapeutic target for AAA.

Increased Mobility of the Atrial Septum in Aortic Root Dilation: An Observational Study on Transesophageal Echocardiography

Background: There is a growing interest in the relationship between atrial septal anatomy and cardioembolic stroke. Anecdotal reports suggest that the enlargement of the aortic root could interfere with atrial septal mobility (ASM). We sought to investigate the association between ASM and aortic root dilation.

Methods and Findings: From all consecutive clinically requested transesophageal echocardiogram (TEE) studies performed during the study period in a single institution, we were able to review and evaluate the ASM and anteroposterior length, aortic root diameter, and the prevalence of atrial septal aneurysm (ASA) and of patent foramen ovale (PFO) in 336 studies. Additional variables, such as left ventricular ejection fraction, left atrial diameter, diastolic dysfunction, age, sex, weight, height, previous stroke, atrial fibrillation, and TEE indication, were extracted from patient medical records and echocardiographic clinical reports. In 336 patients, we found a mean ASM of 3.4 mm, ranging from 0 to 21 mm; 15% had ASA and 14% had PFO. There was a 1.0 mm increase in ASM for every 10-mm increase in aortic root diameter adjusted for age, sex, weight, height, ejection fraction, and left atrial size (B = 0.1; P = 0.04). Aortic diameter was not associated with a smaller septal length (B = 0.03; P = 0.7).

Conclusion: An increased motion of the atrial septum can occur in association with aortic dilation. These findings deserve attention for the relevance of aortic root anatomy in future studies involving atrial septal characteristics and embolic stroke risk.

Height and Mortality from Aortic Aneurysm and Dissection

AIMS

Reports on the association between height and aortic disease have been modest, and there are only a few studies investigating the association between height and mortality from specific aortic disease types or by sex.

METHODS

We conducted the Japan Collaborative Cohort Study, a prospective study of 99,067 Japanese (41,730 men and 57,337 women) aged 40-79 years old. Height was self-reported, and the participants were followed up from 1988-1989 to the end of 2009. Sex-specific hazard ratios (95% confidence intervals) of mortality from aortic disease type according to sex-specific quartiles of height were analyzed using the Cox proportional hazards model.

RESULTS

During the median follow-up period of 19.1 years, the numbers of deaths due to aortic aneurysm, thoracic aortic aneurysm, abdominal aortic aneurysm, and aortic dissection were 87, 29, 48, and 56 among men and 35, 17, 15, and 65 among women, respectively. The sex-specific multivariate hazard ratios (95% confidence intervals) and p for trend for the highest versus lowest quartiles of height were 1.10 (0.66-1.83), p=0.58 among men and 1.54 (0.85-2.79), p=0.06 among women for total aortic disease; 1.85 (0.80-4.28), p=0.16 among men and 5.67 (0.90-35.77), p=0.08 among women for abdominal aortic aneurysm; and 1.13 (0.48-2.64), p=0.65 among men and 1.70 (0.82-3.50), p=0.04 among women for aortic dissection. The positive association was observed for both sexes, albeit more prominent among women. No association was found between height and mortality from thoracic aortic aneurysms.

CONCLUSIONS

As per our findings, we were able to determine that height was positively associated with mortality from abdominal aortic aneurysm in the Japanese population.

The Prevalence of Concomitant Abdominal Aortic Aneurysm and Cancer

Cancers and abdominal aortic aneurysms (AAA) cause substantial morbidity and mortality and commonly develop in old age. It has been previously reported that AAA patients have a high prevalence of cancers, which has raised the question of whether this is a simple collision, association or causation. Clinical trials or observational studies with sufficient power to prove this association between them were limited because of the relatively low frequency and slow disease process of both diseases. We aimed to determine whether there is a significant association between AAA and cancers using nationwide data. The patients aged > 50 years and diagnosed with AAA between 2002 and 2015, patients with heart failure (HF) and controls without an AAA or HF matched by age, sex and cardiovascular risk factors were enrolled from the national sample cohort from the National Health Insurance claims database of South Korea. The primary outcome was the prevalence rate of cancers in the participants with and without an AAA. The secondary outcome was cancer-related survival and cancer risk. Overall, 823 AAA patients (mean (standard deviation) age, 71.8 (9.4) years; 552 (67.1%) men) and matching 823 HF patients and 823 controls were identified. The prevalence of cancers was 45.2% (372/823), 41.7% (343/823) and 35.7% (294/823) in the AAA, HF and control groups, respectively; it was significantly higher in the AAA group than in the control group (p < 0.001). The risk of developing cancer was higher in the AAA patients than in the controls (adjusted odds ratio (OR), 1.52 (95% confidence interval [CI], 1.24-1.86), p < 0.001) and in the HF patients (adjusted OR, 1.37 (1.24-1.86), p = 0.006). The cancer-related death rate was 2.64 times higher (95% CI, 2.22-3.13; p < 0.001) for the AAA patients and 1.63 times higher (95% CI, 1.37-1.92; p < 0.001) for the HF patients than for the controls. The most common causes of death in the AAA patients were cancer and cardiovascular disease. There was a significantly increased risk of cancer in the AAA than in the HF and control groups. Therefore, appropriate screening algorithms might be necessary for earlier detection of both diseases to improve long-term survival.

Mechano-chemo-biological Computational Models for Arteries in Health, Disease and Healing: From Tissue Remodelling to Drug-eluting Devices

This review aims to highlight urgent priorities for the computational biomechanics community in the framework of mechano-chemo-biological models. Recent approaches, promising directions and open challenges on the computational modelling of arterial tissues in health and disease are introduced and investigated, together with in silico approaches for the analysis of drug-eluting stents that promote pharmacological-induced healing. The paper addresses a number of chemo-biological phenomena that are generally neglected in biomechanical engineering models but are most likely instrumental for the onset and the progression of arterial diseases. An interdisciplinary effort is thus encouraged for providing the tools for an effective in silico insight into medical problems. An integrated mechano-chemo-biological perspective is believed to be a fundamental missing piece for crossing the bridge between computational engineering and life sciences, and for bringing computational biomechanics into medical research and clinical practice.

Appraisal of transthoracic echocardiography for opportunistic screening of abdominal aortic aneurysm

ABSTRACT

Abdominal aortic aneurysm is a life threatening disease. Most of the patients diagnosed incidentally because of the asymptomatic nature of this disease. This study aimed to determine the frequency of abdominal aortic aneurysm and evaluate the value of opportunistic screening during transthoracic echocardiography.A total of 5138 patients referred for echocardiographic evaluation for any reason were screened for abdominal aortic aneurysm between November 2014 to July 2019. The aneurysm was defined as an abdominal aorta with a diameter greater than 30 mm, or segmental dilatation of more than 50% of its size in non-dilated parts.The overall frequency of abdominal aortic aneurysm was 2.2% (n = 109) in the study population. Male sex (P < .001), older age (P < .001), presence of diastolic dysfunction (P = .036), hypertension (P < .001), coronary artery disease (P < .001), and hyperlipidemia (P < .001) were associated with abdominal aortic aneurysm. Patients with aneurysm had significantly increased diameters of the aortic trunk (P < .001) and ascending aorta (P < .001), significantly thicker interventricular septum (P < .001) and posterior wall (P < .001), significantly increased end-diastolic diameter (P < .001) and enlarged left atrium (P < .001), and significantly decreased ejection fraction (P < .001). The mostly met criteria for screening abdominal aortic aneurysm in international guidelines was the age of the patients.Based on the results of this study, screening patients over 60 years of age who undergo a transthoracic echocardiography for any reason would be beneficial to detect an asymptomatic abdominal aortic aneurysm in Turkish population.

Aortic Dissection and Other Acute Aortic Syndromes: Diagnostic Imaging Findings from Acute to Chronic Longitudinal Progression

Acute aortic dissection is the prototype of acute aortic syndromes (AASs), which include intramural hematoma, limited intimal tear, penetrating atherosclerotic ulcer, traumatic or iatrogenic aortic dissection, and leaking or ruptured aortic aneurysm. The manifestation is usually sudden and catastrophic with acutely severe tearing chest or back pain. However, clinical symptoms do not allow distinction between AAS types and other acute pathologic conditions. Diagnostic imaging is essential to rapidly confirm and accurately diagnose the type, magnitude, and complications of AASs. CT fast acquisition of volumetric datasets has become instrumental in diagnosis, surveillance, and intervention planning. Most critical findings affecting initial intervention and prognosis are obtained at CT, including involvement of the ascending aorta, primary intimal tear location, rupture, malperfusion, size and patency of the false lumen, complexity and extent of the dissection, maximum caliber of the aorta, and progression or postintervention complications. Involvement of the ascending aorta-Stanford type A-has the most rapid lethal complications and requires surgical intervention to affect its morbidity and mortality. Lesions not involving the ascending aorta-Stanford type B-have a lesser rate of complications in the acute phase. During the acute to longitudinal progression, various specific and nonspecific imaging findings are encountered, including pleural and pericardial effusions, fluid collections, progression including aortic enlargement, and postoperative changes that can be discerned at CT. A systematic analysis algorithm is proposed for CT of the entire aorta throughout the continuum of AASs into the chronic and posttreated disease state, which synthesizes and communicates salient findings to all care providers. Online supplemental material is available for this article. ^©RSNA, 2021.

Epidemiology of thoracoabdominal aortic aneurysms

Thoracoabdominal aortic aneurysms, although rare, continue to be associated with high morbidity and mortality in the modern era of vascular surgery, and knowledge of this disease is essential for those in clinical practice. Given the clinically silent nature of the disease, it is difficult to determine disease incidence, with most epidemiologic recommendations not made based on evidence regarding those diagnosed with the disease, but extrapolated from data on surgical outcomes. It appears that although men are more likely to develop thoracoabdominal aortic aneurysms, the distribution is not as skewed as in abdominal aortic aneurysms. Current evidence suggests that Black and Hispanic patients continue to have disproportionately poor disease outcomes, mostly attributed to later presentation and undergoing interventions at lower-volume centers. Although select patients meet criteria for disease screening based on personal or family history of aneurysmal disease, general population screening has not been recommended by any professional organization to date. Vascular surgeons need to continue to be at the forefront of thoracoabdominal aortic aneurysm management, especially as care becomes centered around comprehensive "aortic care centers" and as more endovascular therapies become available.

Study on the association of wall shear stress and vessel structural stress with atherosclerosis: An experimental animal study

BACKGROUND AND AIMS

Artery is subject to wall shear stress (WSS) and vessel structural stress (VSS) simultaneously. This study is designed to explore the role of VSS in development of atherosclerosis.

METHODS

Silastic collars were deployed on the carotid to create two constrictions on 13 rabbits for a distinct mechanical environment at the constriction. MRI was performed to visualize arteries' configuration. Animals with high fat (n = 9; Model-group) and normal diet (n = 4; Control-group) were sacrificed after 16 weeks. 3D fluid-structure interaction analysis was performed to quantify WSS and VSS simultaneously.

RESULTS

Twenty plaques were found in Model-group and 3 in Control-group. In Model-group, 8 plaques located proximally to the first constriction (Region-1, close to the heart) and 7 distally to the second (Region-2, close to the head) and 5 plaques were found on the contralateral side of 3 rabbits. Plaques at Region-1 tended to be bigger than those at Region-2 and the macrophage density at these locations was comparable. Minimum time-averaged WSS (TAWSS) in Region-1 was significantly higher than that in Region-2, and both maximum oscillatory shear index (OSI) and particle relative residence time (RRT) were significantly lower. Peak and mean VSS in Region-1 were significantly higher than those in Region-2. Correlation analyses indicated that low TAWSS, high OSI and RRT were only associated with plaque in Region-2, while lesions in Region-1 were only associated with high VSS. Moreover, only VSS was associated with wall thickness of plaque-free regions in both regions.

CONCLUSIONS

VSS might contribute to the initialization and development of atherosclerosis solely or in combination with WSS.

Thoracic aortic size in Brazilian smokers: measures using low-dose chest computed tomography anatomical and epidemiological assessment

OBJECTIVES

Thoracic aortic aneurysms (TAAs) represent one-third of the hospitalizations for aortic diseases. The prevalence rate depends on the definition of the normal size of the aorta, which is quite variable, depending on the population studied. The aim of this study was to evaluate the characteristics of the thoracic aorta of Brazilian smokers, identifying the normal size of the aorta, presence of anatomical variations, and prevalence of TAA.

MATERIALS AND METHODS

A total of 711 patients underwent radiological evaluation with low-dose computed tomography (CT) from January 2013 to July 2014 with the initial objective of lung nodule tracking. Two examiners evaluated these images, and measurements of maximum and serial diameters were performed manually in true orthogonal planes. Serial diameter measurements were taken every 2 cm in the ascending aorta and 5 cm in the descending segment. We searched for anatomical variations, aortic arch type, and correlations between anatomical characteristics, sex, body mass index, and body surface area (BSA).

RESULTS

The maximum diameters were 33.61 (standard deviation [SD] 3.88), 28.66 (SD 2.89), and 28.36 mm (SD 3.09) for the ascending segment, aortic arch, and descending segment, respectively. A positive correlation was found between male sex, age, and BSA and aorta diameter. The bovine arch was the most common variation of the aortic arch type, and we found one (0.14%) case of TAA.

CONCLUSIONS

This study with low-dose CT allowed the determination of the mean diameters of the ascending aorta, aortic arch, and descending aorta in Brazilian smokers and TAA prevalence.

Covered or Not, Here I Come: Stanford Type B Aortic Dissection Repair With a Covered and Uncovered Stent Hybrid Technique

The complications resulting from aortic dissections are often devastating. Historically, when a Stanford B aortic dissection extended into the visceral abdominal aorta, only surgical management was considered to limit visceral organ malperfusion. Complications of surgical management for Stanford B aortic dissections are as high as 50%. The inherently high complication and mortality rate for any acute aortic dissection, in addition to the complication rates resulting from surgical management, have demonstrated poor outcomes. This is especially true when aortic dissections involve the visceral segment, where thoracic endovascular aortic repair (TEVAR) becomes limited or contraindicated. In the last two decades, various approaches for TEVAR have improved in both endograft design and interventional technique. The current literature demonstrates improved outcomes for patients that receive TEVAR for Stanford B aortic dissections, including those that involve the visceral segment. Despite favorable prognostic advancement in TEVAR, the proven management complexity of Stanford B aortic dissections continue to reflect the pitfalls of the endovascular devices that are currently available. We describe a covered and uncovered stent hybrid technique in patients with complicated Stanford B aortic dissections involving the visceral segment, considering these deficiencies. Hundred percent technical success was demonstrated in the short and mid-term surveillance periods.

Obstructive sleep apnoea and the progression of thoracic aortic aneurysm: a prospective cohort study

BACKGROUND

Obstructive sleep apnoea (OSA) is associated with an increased prevalence of aortic aneurysms and it has also been suggested that severe OSA furthers aneurysm expansion in the abdomen. We evaluated whether OSA is a risk factor for the progression of ascending thoracic aortic aneurysm (TAA).

METHODS

Patients with TAA underwent yearly standardised echocardiographic measurements of the ascending aorta over 3 years and two level III sleep studies. The primary outcome was the expansion rate of TAA in relation to the apnoea-hypopnoea index (AHI). Secondary outcomes included surveillance for aortic events (composite end-points of rupture/dissection, elective surgery or death).

RESULTS

Between July 2014 and March 2020, 230 patients (median age 70 years, 83.5% male) participated in the cohort. At baseline, 34.8% of patients had AHI ≥15 events·h^-1. There was no association between TAA diameter and AHI at baseline. After 3 years, mean±sd expansion rates were 0.55±1.25 mm at the aortic sinus and 0.60±1.12 mm at the ascending aorta. In the regression analysis, after controlling for baseline diameter and cardiovascular risk factors, there was strong evidence for a positive association of TAA expansion with AHI (aortic sinus estimate 0.025 mm, 95% CI 0.009-0.040 mm; p<0.001 and ascending aorta estimate 0.026 mm, 95% CI 0.011-0.041 mm; p=0.001). 20 participants (8%) experienced an aortic event; however, there was no association with OSA severity.

CONCLUSION

OSA may be a modest but independent risk factor for faster TAA expansion and thus potentially contributes to life-threatening complications in aortic disease.

An aortic wall to vertebral body fistula presenting as a lytic lesion

There have been multiple reported cases of aortic fistulas but few cases of aorta to vertebral body fistulas and no aortic wall to vertebral body fistulas have been reported. Here we present a case of a patient who is status post thoracic aortic aneurysm (TAA) repair and found to have a lytic vertebral body lesion. Biopsy of the mass revealed blood products without evidence of malignancy and further investigation revealed a fistulous tract between the aortic wall and the vertebral body causing a vertebral body hematoma.

Comparisons of Risk Factors for Abdominal Aortic Aneurysm and Coronary Heart Disease: A Prospective Cohort Study

Even though abdominal aortic aneurysm (AAA) and coronary heart disease (CHD) are both related to atherosclerosis, there could be important differences in risk factors. Based on Malmö Diet and Cancer Cohort, the incidence of AAA and CHD was followed prospectively. Cox regression was used to calculate the association of each factor with AAA and CHD and hazards ratio were compared using a modified Lunn-McNeil method; 447 participants developed AAA and 3129 developed CHD. After multivariate adjustments, smoking, antihypertensive medications, lipid-lowing medications, systolic and diastolic blood pressures, apolipoprotein (Apo) A1 (inversely), ApoB, ApoB/ApoA1 ratio, total leukocyte count, neutrophil count, and neutrophil to lymphocyte ratio were associated with the risks of both AAA and CHD. When comparing risk factor profiles for the 2 diseases, smoking, diastolic blood pressure, ApoA1, and ApoB/ApoA1 ratio had stronger associations with risk of AAA than with risk of CHD, while diabetes and unmarried status showed increased risk of CHD, but not of AAA (all P values for equal association <.01). The results from this big population study confirm that the risk factor profiles for AAA and CHD show not only many similarities but also several important differences.

Four-dimensional-flow Magnetic Resonance Imaging of the Aortic Valve and Thoracic Aorta

Blood flow through the heart and great vessels is sensitive to time and multiple velocity directions. The assessment of its three-dimensional nature has been limited. Recent advances in magnetic resonance imaging (MRI) allow the comprehensive visualization and quantification of in vivo flow dynamics using four-dimensional (4D)-flow MRI. In addition, the technique provides the opportunity to obtain advanced hemodynamic measures. This article introduces 4D-flow MRI as it is currently used for blood flow visualization and quantification of cardiac hemodynamic parameters. It discusses its advantages relative to other flow MRI techniques and describes its potential clinical applications.

Pathogenic mechanisms and the potential of drug therapies for aortic aneurysm

Aortic aneurysm is a permanent focal dilation of the aorta. It is usually an asymptomatic disease but can lead to sudden death due to aortic rupture. Aortic aneurysm-related mortalities are estimated at ∼200,000 deaths per year worldwide. Because no pharmacological treatment has been found to be effective so far, surgical repair remains the only treatment for aortic aneurysm. Aortic aneurysm results from changes in the aortic wall structure due to loss of smooth muscle cells and degradation of the extracellular matrix and can form in different regions of the aorta. Research over the past decade has identified novel contributors to aneurysm formation and progression. The present review provides an overview of cellular and noncellular factors as well as enzymes that process extracellular matrix and regulate cellular functions (e.g., matrix metalloproteinases, granzymes, and cathepsins) in the context of aneurysm pathogenesis. An update of clinical trials focusing on therapeutic strategies to slow abdominal aortic aneurysm growth and efforts underway to develop effective pharmacological treatments is also provided.

Genetics of Thoracic and Abdominal Aortic Diseases

Dissections or ruptures of aortic aneurysms remain a leading cause of death in the developed world, with the majority of deaths being preventable if individuals at risk are identified and properly managed. Genetic variants predispose individuals to these aortic diseases. In the case of thoracic aortic aneurysm and dissections (thoracic aortic disease), genetic data can be used to identify some at-risk individuals and dictate management of the associated vascular disease. For abdominal aortic aneurysms, genetic associations have been identified, which provide insight on the molecular pathogenesis but cannot be used clinically yet to identify individuals at risk for abdominal aortic aneurysms. This compendium will discuss our current understanding of the genetic basis of thoracic aortic disease and abdominal aortic aneurysm disease. Although both diseases share several pathogenic similarities, including proteolytic elastic tissue degeneration and smooth muscle dysfunction, they also have several distinct differences, including population prevalence and modes of inheritance.

Prevalence of Obstructive Sleep Apnea in Patients with Thoracic Aortic Aneurysm: A Prospective, Parallel Cohort Study

BACKGROUND

The pathogenesis and etiology of thoracic aortic aneurysms (TAA) are largely unknown. Preliminary data from patients with aortic dissection and abdominal aneurysms suggest a causal link of obstructive sleep apnea (OSA) on aortic disease.

OBJECTIVES

The aim of the study was to assess the prevalence of OSA in patients with TAA compared to a matched control group.

METHOD

In this prospective parallel-cohort study, we 2-to-1 matched 208 patients with verified TAA (at the aortic sinus and/or ascending aorta) to 104 controls without TAA according to sex, age, height, weight, and left ventricular ejection fraction. All participants underwent an ultrasound of the thoracic aorta and a level III respiratory polygraphy. OSA was defined as apnea-hypopnea index ≥5/h. The prevalence of OSA was compared with conditional logistic regression and controlling for the matching variables.

RESULTS

A total of 312 patients (mean age 65 ± 11 years, 82% male, mean body mass index 27 ± 4 kg/m2) were successfully 2-to-1 matched in the final model. Prevalence of OSA was significantly higher in the TAA-group when compared to the matched control group (63 vs. 47%; odds ratio 1.87 [95% CI 1.05-3.34]; p = 0.03). When applying a higher apnea-hypopnea index threshold (≥15/h), the odds ratio increased to 3.25 (95% CI 1.65-6.42; p < 0.001). The median apnea-hypopnea index was higher in patients with TAA (9.2/h [3.3-20.0] vs. 4.5/h [2.2-11.1], p < 0.001).

CONCLUSIONS

Patients with TAA have a higher prevalence of OSA when compared to the general population. Since OSA is effectively treatable and might contribute to the pathogenesis of TAA, further longitudinal trials are needed to assess the association between OSA and TAA.

Evaluation of the incidence of aortic aneurysms in patients with and without diabetes in Poland in 2012 based on the database of the National Health Fund

INTRODUCTION

There are reports that diabetes mellitus reduces the risk of aortic aneurysms and many reports that diabetes mellitus reduces the risk of abdominal aortic aneurysms. In earlier years there were also studies that did not demonstrate any effects of diabetes on the rate of aortic aneurysms.

MATERIAL AND METHODS

For the year 2012, between 1 January and 31 December, reports for services regarding treatment for aortic aneurysms were found. At the same time, the reports for services associated with diabetes with the main diagnosis of "diabetes mellitus" were found in National Health Fund databases for 2012 with the special determinants.

RESULTS

In Poland in 2012 the mean incidence of aortic aneurysms in both sexes in the group of subjects with diabetes calculated per 100,000 subjects with diabetes was 167.78 ±49.10, and the mean incidence of aortic aneurysms in both sexes in the group of subjects without diabetes calculated per 100,000 of the general population after subtracting the number of subjects with diabetes was 27.72 ±9.40. The incidence of aortic aneurysms among subjects with diabetes was significantly higher (p < 0.001) than the incidence of aortic aneurysms among subjects without diabetes.

CONCLUSIONS

Aortic aneurysms were more frequently observed in the group of patients with diabetes than in those without diabetes. Aortic aneurysms were observed three times more frequently in men than in women. In Poland in 2012, 27.20% of patients diagnosed with aortic aneurysms also had diabetes.

Blood pressure, hypertension and the risk of abdominal aortic aneurysms: a systematic review and meta-analysis of cohort studies

Abdominal aortic aneurysms (AAA) are fatal in 80% of the cases when ruptured. Hypertension has been considered a potential risk factor for AAA; but the findings from prospective cohort studies have not been entirely consistent, nor have they been summarised in a comprehensive meta-analysis. Our aim was to conduct a systematic review and meta-analysis of cohort studies of the association between blood pressure, hypertension and AAA to clarify the strength and shape of these associations. We searched PubMed and Embase databases for relevant cohort studies up to April 30th, 2018. Random-effects models were used to calculate summary relative risks (RRs) and 95% confidence intervals (CIs). The meta-analysis included 21 cohort studies (20 publications) with data on 28,162 cases and 5,440,588 participants. The findings indicate that the RR of AAA in hypertensive patients is 1.66 times (95% CI: 1.49–1.85, I² = 79.3%, n = 13) that of non-hypertensive patients. In addition, there was a 14% (95% CI: 6–23%, I² = 30.5%, n = 6) and a 28% (95% CI: 12–46%, I² = 80.1%, n = 6) increase in the RR of AAA for every 20 mmHg and 10 mmHg increase in systolic blood pressure (SBP) and diastolic blood pressure (DBP), respectively. The analysis of DBP showed evidence of a strong and highly significant nonlinear dose–response relationship (p < 0.001) with a steeper association from 80 mmHg and above. This meta-analysis suggests that hypertension increases the risk of developing AAA by 66%. Further studies are needed to clarify the underlying mechanism explaining the much stronger association between DBP and AAA than for SBP.

Fluid-Structure Interaction in Abdominal Aortic Aneurysms: Effect of Haematocrit

The Abdominal Aortic Aneurysm (AAA) is a local dilation of the abdominal aorta and it is a cause for serious concern because of the high mortality associated with its rupture. Consequently, the understanding of the phenomena related to the creation and the progression of an AAA is of crucial importance. In this work, the complicated interaction between the blood flow and the AAA wall is numerically examined using a fully coupled Fluid-Structure Interaction (FSI) method. The study investigates the possible link between the dynamic behavior of an AAA and the blood viscosity variations attributed to the haematocrit value, while it also incorporates the pulsatile blood flow, the non-Newtonian behavior of blood and the hyperelasticity of the arterial wall. It was found that blood viscosity has no significant effect on von Mises stress magnitude and distribution, whereas there is a close relation between the haematocrit value and the Wall Shear Stress (WSS) magnitude in AAAs. This WSS variation can possibly alter the mechanical properties of the arterial wall and increase its growth rate or even its rupture possibility. The relationship between haematocrit and dynamic behavior of an AAA can be helpful in designing a patient specific treatment.

An evaluation of the effect of an angiotensin-converting enzyme inhibitor on the growth rate of small abdominal aortic aneurysms: a randomised placebo-controlled trial (AARDVARK)

BACKGROUND

Although data are inconsistent, angiotensin-converting enzyme inhibitors (ACE-Is) have been associated with a reduced incidence of abdominal aortic aneurysm (AAA) rupture in analysis of administrative databases.

OBJECTIVES

(1) To investigate whether or not the ACE-I perindopril (Coversyl arginine, Servier) reduces small AAA growth rate and (2) to evaluate blood pressure (BP)-independent effects of perindopril on small AAA growth and to compare the repeatability of measurement of internal and external aneurysm diameters.

DESIGN

A three-arm, multicentre, single-blind, randomised placebo-controlled trial.

SETTING

Fourteen hospitals in England.

PARTICIPANTS

Men or women aged ≥ 55 years with an AAA of 3.0-5.4 cm in diameter by internal or external measurement according to ultrasonography and who met the trial eligibility criteria.

INTERVENTIONS

Patients were randomised to receive 10 mg of perindopril arginine daily, 5 mg of the calcium channel blocker amlodipine daily or placebo daily.

MAIN OUTCOME MEASURES

The primary outcome was AAA diameter growth using external measurements in the longitudinal plane, which in-trial studies suggested was the preferred measure. Secondary outcome measures included AAA rupture, AAA repair, modelling of the time taken for the AAA to reach the threshold for intervention (5.5 cm) or referral for surgery, tolerance of study medication (measured by compliance, adverse events and quality of life) and a comparison of the repeatability of measures of internal and external AAA diameter. Patients were followed up every 3-6 months over 2 years.

RESULTS

In total, 227 patients were recruited and randomised into the three groups, which were generally well matched at baseline. Multilevel modelling was used to determine the maximum likelihood estimates for AAA diameter growth. No significant differences in the estimates of annual growth were apparent [1.68 (standard error 0.02) mm, 1.77 (0.02) mm and 1.81 (0.02) mm in the placebo, perindopril and amlodipine groups, respectively]. Similarly, no significant differences in the slopes of modelled growth over time were apparent between perindopril and placebo (p = 0.78) or between perindopril and amlodipine (p = 0.89). The results were essentially unaffected by adjustment for potential confounders. Compliance, measured by pill counts, was good throughout (> 80% at all visit time points). There were no significant in-trial safety concerns. Six patients withdrew because of adverse events attributed to the study medications (n = 2 perindopril, n = 4 amlodipine). No patients ruptured their AAA and 27 underwent elective surgery during the trial (n = 9 placebo, n = 10 perindopril, n = 8 amlodipine).

CONCLUSIONS

We were unable to demonstrate a significant impact of perindopril compared with placebo or amlodipine on small AAA growth over a 2-year period. Furthermore, there were no differences in the times to reach a diameter of 5.5 cm or undergo surgery among the three groups. Perindopril and amlodipine were well tolerated by this population. External AAA measurements were found to be more repeatable than internal measurements. The observed AAA growth measurement variability was greater than that expected pre trial. This, combined with slower than expected mean growth rates, resulted in our having limited power to detect small differences between growth rates and hence this adds uncertainty to the interpretation of the results. Several further analyses are planned including a multivariate analysis of determinants of AAA growth, an evaluation of the possible differential effect of perindopril on fast AAA growth and an investigation into the roles of central BP and BP variability on AAA growth.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN51383267.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 20, No. 59. See the NIHR Journals Library website for further project information. The NIHR Biomedical Research Centre based at Imperial College NHS Trust supported the trial. Servier provided perindopril at no charge.

Muse Cells and Aortic Aneurysm

The aorta is a well-organized, multilayered structure comprising several cell types, namely, endothelial cells (ECs), vascular smooth muscle cells (VSMCs), and fibroblasts, as well as an extracellular matrix (ECM), which includes elastic and collagen fibers. Aortic aneurysms (AAs) are defined as progressive enlargements of the aorta that carries an incremental risk of rupture as the diameter increases over time. The destruction of the aortic wall tissue is triggered by atherosclerosis, inflammation, and oxidative stress, leading to the activation of matrix metalloproteinases (MMPs), and inflammatory cytokines and chemokines, resulting in the loss of the structural back bone of VSMCs, ECM, and ECs. To date, cell-based therapy has been applied to animal models using several types of cells, such as VSMCs, ECs, and mesenchymal stem cells (MSCs). Although these cells indeed deliver beneficial outcomes for AAs, particularly by paracrine and immunomodulatory effects, the attenuation of aneurysmal dilation with a robust tissue repair is insufficient. Meanwhile, multilineage-differentiating stress-enduring (Muse) cells are known to be endogenous non-tumorigenic pluripotent-like stem cells that are included as several percent of MSCs. Since Muse cells are pluripotent-like, they have the ability to differentiate into cells representative of all three germ layers from a single cell and to self-renew. Moreover, Muse cells are able to home to the site of damage following simple intravenous injection and repair the tissue by replenishing new functional cells through spontaneous differentiation into tissue-compatible cells. Given these unique properties, Muse cells are expected to provide an efficient therapeutic efficacy for AA by simple intravenous injection. In this chapter, we summarize several studies on Muse cell therapy for AA including our recent data, in comparison with other kinds of cell therapies.

Alcohol consumption and mortality from aortic disease among Japanese men: The Japan Collaborative Cohort study

BACKGROUND AND AIMS

Only a few population-based prospective studies have examined the association between alcohol consumption and abdominal aortic aneurysm, and the results are inconsistent. Moreover, no evidence exists for aortic dissection. We examined the effect of alcohol consumption on risk of mortality from aortic diseases.

METHODS

A total of 34,720 men from the Japan Collaborative Cohort study, aged 40-79 years, without history of cardiovascular disease and cancer at baseline 1988 and 1990 were followed up until the end of 2009 for their mortality and its underlying cause. Hazard ratios of mortality from aortic diseases were estimated according to alcohol consumption categories of never-drinkers, ex-drinkers, regular drinkers of ≤30 g, and >30 g ethanol per day.

RESULTS

During the median 17.9-year follow-up period, 45 men died of aortic dissection and 41 men died of abdominal aortic aneurysm. Light to moderate drinkers of ≤30 g ethanol per day had lower risk of mortality from total aortic disease and aortic dissection compared to never-drinkers. The respective multivariable hazard ratios (95% confidence intervals) were 0.46 (0.28-0.76) for total aortic disease and 0.16 (0.05-0.50) for aortic dissection. Heavy drinkers of >30 g ethanol per day did not have reduced risk of mortality from total aortic disease, albeit had risk variation between aortic dissection and abdominal aortic aneurysm.

CONCLUSIONS

Light to moderate alcohol consumption was associated with reduced mortality from aortic disease among Japanese men.

Advanced Oxidation Protein Products and Carbonylated Proteins as Biomarkers of Oxidative Stress in Selected Atherosclerosis-Mediated Diseases

Objectives

The main question of this study was to evaluate the intensity of oxidative protein modification shown as advanced oxidation protein products (AOPP) and carbonylated proteins, expressed as protein carbonyl content (C=O) in abdominal aortic aneurysms (AAA), aortoiliac occlusive disease (AIOD), and chronic kidney disease (CKD).

Design and Methods

The study was carried out in a group of 35 AAA patients and 13 AIOD patients. However, CKD patients were divided into two groups: predialysis (PRE) included 50 patients or hemodialysis (HD) consisted of 34 patients. AOPP and C=O were measured using colorimetric assay kit, while C-reactive protein concentration was measured by high-sensitivity assay (hsCRP).

Results

The concentration of AOPP in both AAA and AIOD groups was higher than in PRE and HD groups according to descending order: AAA~AIOD > HD > PRE. The content of C=O was higher in the PRE group in comparison to AIOD and AAA according to the descending order: PRE~HD > AAA~AIOD.

Conclusions

AAA, AIOD, and CKD-related atherosclerosis (PRE and HD) contribute to the changes in the formation of AOPP and C=O. They may promote modification of proteins in a different way, probably due to the various factors that influence oxidative stress here.

Associations of Diabetes and Obesity with Risk of Abdominal Aortic Aneurysm in Men

Background. The associations of diabetes and obesity with the risk of abdominal aortic aneurysm (AAA) are inconclusive in previous studies. Subjects/Methods. We conducted prospective analysis in the Physicians' Health Study. Among 25,554 male physicians aged ≥ 50 years who reported no AAA at baseline, 471 reported a newly diagnosed AAA during a mean of 10.4 years' follow-up. Results. Compared with men who had baseline body mass index (BMI) < 25 kg/m², the multivariable hazard ratio (HR [95% CI]) of newly diagnosed AAA was 1.30 [1.06-1.59] for BMI 25-<30 kg/m² and 1.69 [1.24-2.30] for BMI ≥ 30 kg/m². The risk of diagnosed AAA was significantly higher by 6% with each unit increase in baseline BMI. This association was consistent regardless of the other known AAA risk factors and preexisting vascular diseases. Overall, baseline history of diabetes tended to be associated with a lower risk of diagnosed AAA (HR = 0.79 [0.57-1.11]); this association appeared to vary by follow-up time (HR = 1.56 and 0.63 during ≤ and >2 years' follow-up, resp.). Conclusion. In a large cohort of middle-aged and older men, obesity was associated with a higher risk, while history of diabetes tended to associate with a lower risk of diagnosed AAA, particularly over longer follow-up.

Impact of Statins on Risk of Stroke: A Meta-Analysis

Background:

Evidence from randomized, controlled trials suggests that reduction of low-density lipoprotein cholesterol with hydroxymethylglutaryl coenzyme A reductase inhibitor (statin) therapy in patients at high risk for cardiovascular disease reduces the incidence of ischemic stroke; however, data from large epidemiologic observational studies suggest an inverse relationship between risk of hemorrhagic stroke and cholesterol levels.

Objective:

To perform a meta-analysis of randomized controlled trials to assess the effect of statin therapy on all cerebrovascular events (CVEs), ischemic stroke, and hemorrhagic stroke.

Methods:

A systematic literature search of MEDLINE, EMBASE, Cumulative Index to Nursing&Allied Health Literature, and Web of Science citations from June 1975 through September 2006 was performed to identify randomized controlled trials of statin therapy. Trials were included if they met the following criteria: (1) controlled clinical trials of statin therapy versus placebo, (2) well-described protocol, and (3) data reported on incidence of all CVEs, ischemic stroke, or hemorrhagic stroke. All data were independently extracted by 3 investigators.

Results:

Weighted averages are reported as relative risk with 95% confidence intervals. A total of 26 trials (N = 100,560) reported incidence on all CVEs. Six trials (n = 37,292) reported incidence of ischemic stroke and 9 trials (n = 57,895) were included in the hemorrhagic stroke analysis. Statin therapy significantly reduced the risk of all CVEs (RR 0.83; 95% CI 0.76 to 0.91) and the risk of ischemic stroke (RR 0.79; 95% CI 0.63 to 0.99). Statin therapy did not significantly reduce risk of hemorrhagic stroke (RR 1, 11; 95% CI 0.77 to 1.60).

Conclusions:

Statin therapy significantly reduces risk of developing all CVEs and ischemic stroke; however, it is associated with a nonsignificant increase in risk of hemorrhagic stroke.

Meta-Analysis of Genome-Wide Association Studies for Abdominal Aortic Aneurysm Identifies Four New Disease-Specific Risk Loci

Supplemental Digital Content is available in the text.

Rationale:

Abdominal aortic aneurysm (AAA) is a complex disease with both genetic and environmental risk factors. Together, 6 previously identified risk loci only explain a small proportion of the heritability of AAA.

Objective:

To identify additional AAA risk loci using data from all available genome-wide association studies.

Methods and Results:

Through a meta-analysis of 6 genome-wide association study data sets and a validation study totaling 10 204 cases and 107 766 controls, we identified 4 new AAA risk loci: 1q32.3 (SMYD2), 13q12.11 (LINC00540), 20q13.12 (near PCIF1/MMP9/ZNF335), and 21q22.2 (ERG). In various database searches, we observed no new associations between the lead AAA single nucleotide polymorphisms and coronary artery disease, blood pressure, lipids, or diabetes mellitus. Network analyses identified ERG, IL6R, and LDLR as modifiers of MMP9, with a direct interaction between ERG and MMP9.

Conclusions:

The 4 new risk loci for AAA seem to be specific for AAA compared with other cardiovascular diseases and related traits suggesting that traditional cardiovascular risk factor management may only have limited value in preventing the progression of aneurysmal disease.

Angiopoietin-2 attenuates angiotensin II-induced aortic aneurysm and atherosclerosis in apolipoprotein E-deficient mice

Angiogenesis and inflammation are implicated in aortic aneurysm and atherosclerosis and regulated by angiopoietin-2 (Angpt2). The effect of Angpt2 administration on experimental aortic aneurysm and atherosclerosis was examined. Six-month-old male apolipoprotein E deficient (ApoE^-/-) mice were infused with angiotensin II (AngII) and administered subcutaneous human Fc-protein (control) or recombinant Angpt2 (rAngpt2) over 14 days. Administration of rAngpt2 significantly inhibited AngII-induced aortic dilatation and rupture of the suprarenal aorta (SRA), and development of atherosclerosis within the aortic arch. These effects were blood pressure and plasma lipoprotein independent and associated with Tie2 activation and down-regulation of monocyte chemotactic protein-1 (MCP-1) within the SRA. Plasma concentrations of MCP-1 and interleukin-6 were significantly lower in mice receiving rAngpt2. Immunostaining for the monocyte/macrophage marker MOMA-2 and the angiogenesis marker CD31 within the SRA were less in mice receiving rAngpt2 than controls. The percentage of inflammatory (Ly6C^hi) monocytes within the bone marrow was increased while that in peripheral blood was decreased by rAngpt2 administration. In conclusion, administration of rAngpt2 attenuated angiotensin II-induced aortic aneurysm and atherosclerosis in ApoE^-/- mice associated with reduced aortic inflammation and angiogenesis. Up-regulation of Angpt2 may have potential therapeutic value in patients with aortic aneurysm and atherosclerosis.