Low wall shear stress predominates at sites of abdominal aortic aneurysm rupture

Boyd, April J.; Kühn, Dietmar; Lozowy, Richard J.; Kulbisky, Gordon P

doi:10.1016/j.jvs.2015.01.040

Cited by 191 publications

(133 citation statements)

References 33 publications

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“…37 Several retrospective studies indicate that finite element analysis can identify areas with increased risk of aneurysm expansion and rupture. [38][39][40] A study of 30 asymptomatic, 15 symptomatic, and 15 ruptured AAA suggested that PWRI was the parameter that best distinguished between asymptomatic and symptomatic AAAs. 40 The same group reported that regions of the AAA with increased PWRI had increased histopathological degeneration on examination of aortic wall specimens obtained at surgical repair.…”

Section: Biomechanical Imagingmentioning

confidence: 99%

Surrogate Markers of Abdominal Aortic Aneurysm Progression

Wanhainen

Mani

Golledge

2016

ATVB

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Abstract-The natural course of many abdominal aortic aneurysms (AAA) is to gradually expand and eventually rupture and monitoring the disease progression is essential to their management. In this publication, we review surrogate markers of AAA progression. AAA diameter remains the most widely used and important marker of AAA growth. Wanhainen et al Surrogate Markers of Aneurysm Progression 237in all studies when a standardized protocol is used. 7,8 One of the challenging aspects to assessing maximum AAA diameter is the variety of methods that can potentially be used and the lack of reporting of the exact techniques used in individual studies. Variations may occur in the plane of acquisition (eg, coronal or sagittal), the axis of measurement (eg, axial or orthogonal), the position of the measuring calipers (eg, inner to inner or outer to outer), the relationship with the cardiac cycle (systole versus diastole), and the selected region of the AAA. 9 It has been suggested that diameters measured perpendicular to the aorta centerline (orthogonal), rather than within the axial plane, are more representative of the true AAA diameter. 4,6 With ultrasound, measurements within the anteroposterior, rather than the transverse plane, have been reported to be more reproducible. 4 There is no current consensus on how to place the calipers when measuring the diameter with ultrasound. Methods used include the outer-to-outer method, where calipers are placed on the outer layer of the aortic wall; the inner-to-inner method, where calipers are placed on the inner layer of the aortic wall; and the leading edge-to-leading edge method, where calipers are placed on the outer layer of the anterior wall and the inner layer of the posterior wall ( Figure 1). Much of the reported variation in ultrasound measured AAA diameter is likely because of the variation in caliper placement. 5,10 The UK Small Aneurysm Trial 11 is based on the measurement of AAA diameter on the outer-to-outer method, and this method has been adopted into the current UK intervention criteria. 12 The inner-to-inner method was used in the Multicentre Aneurysm Screening Study, 13 and consequently it is used in the current UK National Health Service AAA screening programme.14 The leading edgeto-leading edge method is used in the current Swedish AAA screening programme.15 Studies comparing these methods show there is a significant difference in diameters measured with the different methods, which has an impact on the reported prevalence rates of AAA. 5,10 In a Swedish AAA screening study, the difference in mean diameter was 4 mm between inner-toinner and outer-to-outer, which resulted in an astonishing 77% difference in AAA prevalence (ie, 1.3% compared with 2.3%). 5A systematic review of 15 studies reported considerable variation in small AAA growth rates (mean, −0.3 to +4.0 mm/y). 15 The variation could not be explained by differences in initial AAA diameter alone. 16 The authors suggested that methodological issues, such as differences in imaging modalities, variation ...

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Section: Biomechanical Imagingmentioning

confidence: 99%

Surrogate Markers of Abdominal Aortic Aneurysm Progression

Wanhainen

Mani

Golledge

2016

ATVB

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“…With this in mind, we approximated the blood flow as laminar and considered the blood to be an incompressible fluid with a density of 1050 kg/m 3 . The walls of the arteries were characterised by no-slip, rigid wall boundary conditions [5,6,32,35,54,55] and the viscosity was modelled using a non-Newtonian approximation (Carreau-Yasuda, as implemented by Biasetti et al [44]; [56]). By using a non-Newtonian model, as opposed Newtonian, we can capture the macro-scale shear-thinning of the blood, allowing a one-way Lagrangian particle transport model to provide a good prediction of individual blood-cell trajectories within the continuous phase (blood).…”

Section: Physical Assumptions and Boundary Conditionsmentioning

confidence: 99%

“…Furthermore, Rayz et al [31] observed thrombus deposition in certain regions of patient-specific intracranial geometries with an increase in residence time and low WSS. More recently, Boyd et al found that AAA rupture tended to occur in thrombus afflicted regions with predicted flow recirculation and low WSS [32]. In addition, it has been shown that regions of low, oscillatory WSS provide a well-described mechanical stimulus that promotes the inflammatory process by inducing an oxidative response in endothelial vascular cells [33].…”

Section: Introductionmentioning

confidence: 99%

A comparison of hemodynamic metrics and intraluminal thrombus burden in a common iliac artery aneurysm

Kelsey

Powell

Norman

et al. 2016

Numer Methods Biomed Eng

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Aneurysms of the common iliac artery (CIAA) are most commonly seen in association with an abdominal aortic aneurysm (AAA). Isolated CIAAs, in the absence of an AAA, are uncommon. Similar to AAAs, CIAA may develop intraluminal thrombus (ILT). As isolated CIAAs have a contralateral common iliac artery for comparison, they provide an opportunity to study the haemodynamic mechanisms behind ILT formation.In this study, we compared a large isolated CIAA and the contralateral iliac artery using computational fluid dynamics (CFD) to determine if haemodynamic metrics correlate with the location of ILT. We performed a comprehensive CFD study and investigated the residence time of platelets and monocytes, velocity fields, time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI) and endothelial cell activation potential (ECAP). We then correlated these data to ILT burden determined with computed tomography (CT).We found that high cell residence times, low TAWSS, high OSI and high ECAP all correlate with regions of ILT development. Our results show agreement with previous hypotheses of thrombus formation in AAA and provide insights into the computational haemodynamics of iliac artery aneurysms.

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“…Hence, image acquisition, quantification, and analysis methods need standardization to ensure rigor, reproducibility, validity, and reliability. Another potential problem is that NP localization is unlikely to reflect the hemodynamic forces on the aortic wall, which are also relevant to AAA rupture risk (72). …”

Section: Studies Assessing Nps In Aaa Imagingmentioning

confidence: 99%

Use of Nanoparticles As Contrast Agents for the Functional and Molecular Imaging of Abdominal Aortic Aneurysm

Emeto

Alele

Smith

et al. 2017

Front. Cardiovasc. Med.

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Abdominal aortic aneurysm (AAA) is a degenerative disease of the aorta common in adults older than 65 years of age. AAA is usually imaged using ultrasound or computed tomography. Molecular imaging technologies employing nanoparticles (NPs) have been proposed as novel ways to quantify pathological processes, such as inflammation, within AAAs as a means to identify the risk of rapid progression or rupture. This article reviews the current evidence supporting the role of NP-based imaging in the management of AAA. Currently, ultrasmall superparamagnetic NPs enhanced magnetic resonance imaging appears to hold the greatest potential for imaging macrophage-mediated inflammation in human AAA.

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Low wall shear stress predominates at sites of abdominal aortic aneurysm rupture

Cited by 191 publications

References 33 publications

Surrogate Markers of Abdominal Aortic Aneurysm Progression

Surrogate Markers of Abdominal Aortic Aneurysm Progression

A comparison of hemodynamic metrics and intraluminal thrombus burden in a common iliac artery aneurysm

Use of Nanoparticles As Contrast Agents for the Functional and Molecular Imaging of Abdominal Aortic Aneurysm

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