Haemodynamics and stresses in abdominal aortic aneurysms: A fluid-structure interaction study into the effect of proximal neck and iliac bifurcation angle

Drewe, Corey J.; Parker, Louis P.; Kelsey, Lachlan J.; Norman, Paul; Powell, Janet T.; Doyle, Barry

doi:10.1016/j.jbiomech.2017.06.029

Cited by 51 publications

(43 citation statements)

References 17 publications

(13 reference statements)

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“…Overall this study presents results that are in good agreement with previous work on AAAs. Namely, von Mises stress values, along with WSS in the aneurismal sac, coincide qualitatively with previous computational research [14,50]. Furthermore, a qualitative agreement exists with clinical research on AAAs regarding the total displacement of aneurismal wall during one pulse [51].…”

Section: Discussionsupporting

confidence: 87%

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

Stergiou¹,

Kanaris²,

Mouza³

et al. 2018

Preprint

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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 behaviour of an AAA and the blood viscosity variations attributed to the haematocrit value, while it also incorporates the pulsatile blood flow, the non-Newtonian behaviour 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 behaviour of an AAA can be helpful in designing a patient specific treatment.

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Section: Discussionsupporting

confidence: 87%

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

Stergiou¹,

Kanaris²,

Mouza³

et al. 2018

Preprint

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“…These previously hidden elastin antigens are key to the progression of COPD (chronic obstructive pulmonary disease) severity by recruiting additional inflammatory cells, driving its own upregulation; it also promotes polarization toward the M1 proinflammatory macrophage sensitized to elastin-rich tissues, such as the aortic wall. 4 Not surprisingly, in serum of patients with AAA compared with risk factor-matched non-AAA controls, we found a significant elevation in IgGs reactive to aortic-derived elastin. 5 In the inflammation stage, self-sensitized mononuclear cells hone to the infrarenal aorta, a relatively weak section of a large elastic artery prone to excessive mechanical stress secondary to the tapered configuration and shear stress introduced by the aortic bifurcation, exposing previously hidden self-antigens.…”

mentioning

confidence: 53%

Immune Modulation as a Treatment for Abdominal Aortic Aneurysms

Wang

Murphy

2018

Circulation Research

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In the United States, >200 000 new patients are diagnosed with abdominal aortic aneurysm (AAA) each year. Consequently, >40 000 highly morbid aortic reconstructions are performed each year to prevent aneurysm rupture, a catastrophic event associated with near-certain mortality. No pharmaceutical currently exists to slow aneurysm growth, but a 50% reduction in diameter growth per annum could halve the number of aortic reconstructions required. Therefore, successful use of cell therapy to modulate chronic inflammation hallmark to AAA to slow diameter expansion represents a potentially paradigmaltering treatment.There continues to be no US Food and Drug-approved medication to slow or stop AAA growth. This deficit is certainly not because of a lack of effort over the previous decades. Initial investigations focused on the reduction of mechanical stress through decreasing blood pressure and sac pressurization cycles; however, clinical trials investigating drugs, such as, angiotensin II-converting enzyme inhibitors, angiotensin receptor blockers, and β-blockers, all failed to demonstrate a therapeutic reduction of diameter growth compared with placebo. Next, the inhibition of matrix metalloproteinases was trialed with doxycycline, an antibiotic inhibitor of matrix metalloproteinases 2 and 9. Doxycycline also treats species of Chlamydia, which were isolated from the aortic walls of a minority of aneurysmal arteries. Although initial uncontrolled results were promising, therapeutic response was not replicated in large randomized studies. Last, aortic wall inflammation was targeted using statins, a ubiquitous anti-inflammatory, lipid-lowering drug to limited success. The discovery of a nonsurgical treatment for AAA is contingent on the robust understanding of disease pathogenesis, which continues to be nebulous at best.AAA risk factors, such as, tobacco abuse, advancing age, uncontrolled hypertension, male sex, and white ethnicity, have all been well described but fail to provide evidence elucidating pathogenesis. Regardless, existing evidence implicates that disease initiation is multifactorial with a strong genetic element.There has been a focus of late toward the role of autoimmune mechanisms in AAA formation. The characterization of aortic wall inflammation consisting of mononuclear infiltrates, immunoglobulins, cytokines, and proteases implicate both a host innate and adaptive response. Of note, concentrations of CD4 + T cells have been recently discovered in the periadventitial vascular-associated lymphatic tissue expressing identical T cell receptors, against a currently unknown antigen, and therefore clonally expanded, providing crucial evidence for AAA as an autoimmune disease.1 Moreover, interleukin (IL)-17, a cytokine elaborated from the antigen-specific Th17 lymphocyte and overexpressed in autoimmune disorders, is highly expressed in the AAA condition. Abrogation of this cytokine, in animal models, has demonstrated efficacy in decreasing aneurysm diameter growth.2 Although several putative autoantigens have b...

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“…This is not surprising as when the aorta terminates more proximally, a more acute AB angle is required to provide the most direct route to the pelvis and lower limb. Computer simulations of different AB geometries have demonstrated that more acute AB angles result in increased risk of atheroma development (Sharp et al, ; Drewe et al, ). Endovascular treatment of infrainguinal vessel pathologies has also been shown to be more challenging in adults when the AB is acute due to the difficulty in instruments being passed in a contralateral retrograde approach when the angle is less than 45° (Grenon et al, ; Raskin et al, ).…”

Section: Discussionmentioning

confidence: 99%

Differential growth patterns of the abdominal aorta and vertebrae during childhood

2019

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The adult vertebral level of the splanchnic branches of the abdominal aorta relies on a complex series of fusion and regression steps during embryological development, such that variation is common. Little is known however regarding the anatomy of the abdominal aorta in children. This study aimed to investigate the spatial relationship between the abdominal aorta and the vertebral column during childhood development to inform clinical management of pediatric patients. Retrospective multislice computed tomography abdominopelvic angiograms of children aged neonate to 19 years (n = 232) were used to examine vertebral levels of the celiac trunk (CoT), superior mesenteric artery (SMA), inferior mesenteric artery (IMA), and aortic bifurcation (AB) using multiplanar formatting views in OsiriX. The abdominal aorta length, AB angle, and displacement of the aorta from the midline were quantified with the effect of age and sex analyzed using multinomial logistic regression and general linear models. The most frequent origins of CoT, SMA, IMA, and AB were T12, L1, L3, and L4, respectively, with significant variation in vertebral level for each vessel. SMA level was significantly more proximal with age, and CoTand AB demonstrated marked sex differences in vertebral level. As the age of the child increased, AB angle decreased, aortic displacement increased, and the length of the abdominal aorta increased at a slower velocity to the vertebral column (P < 0.001). Our study highlights the variation of the location and geometry of the abdominal aorta in children; this knowledge will positively impact pediatric surgical approaches and endovascular procedures. Clin. Anat. 32:783-793, 2019.

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Haemodynamics and stresses in abdominal aortic aneurysms: A fluid-structure interaction study into the effect of proximal neck and iliac bifurcation angle

Cited by 51 publications

References 17 publications

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

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

Immune Modulation as a Treatment for Abdominal Aortic Aneurysms

Differential growth patterns of the abdominal aorta and vertebrae during childhood

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