Association of Intraluminal Thrombus, Hemodynamic Forces, and Abdominal Aortic Aneurysm Expansion Using Longitudinal CT Images

Zambrano, Byron A.; Gharahi, Hamidreza; Lim, Chae Young; Jaberi, Farhad; Choi, Jongeun; Lee, Whal; Baek, Seungik

doi:10.1007/s10439-015-1461-x

Cited by 90 publications

(95 citation statements)

References 54 publications

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“…Importantly, particular hemodynamic features, including low shear and non-oscillatory flows, have been suggested to favor thrombus deposition in growing lesions [34–36]. The universal lack of luminal occlusion by thrombus within AAAs suggests further that hemodynamic factors also limit the growth of an ILT despite the initial thrombus being, by definition, highly thrombogenic.…”

Section: Methodsmentioning

confidence: 99%

Hemodynamics‐driven deposition of intraluminal thrombus in abdominal aortic aneurysms

Achille

Tellides

Humphrey

2016

Numer Methods Biomed Eng

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Accumulating evidence suggests that intraluminal thrombus plays many roles in the natural history of abdominal aortic aneurysms. There is, therefore, a pressing need for computational models that can describe and predict the initiation and progression of thrombus in aneurysms. In this paper, we introduce a phenomenological metric for thrombus deposition potential and use hemodynamic simulations based on medical images from six patients to identify best-fit values of the two key model parameters. We then introduce a shape optimization method to predict the associated radial growth of the thrombus into the lumen based on the expectation that thrombus initiation will create a thrombogenic surface, which in turn will promote growth until increasing hemodynamically induced frictional forces prevent any further cell or protein deposition. Comparisons between predicted and actual intraluminal thrombus in the six patient-specific aneurysms suggest that this phenomenological description provides a good first estimate of thrombus deposition. We submit further that, because the biologically active region of the thrombus appears to be confined to a thin luminal layer, predictions of morphology alone may be sufficient to inform fluid-solid-growth models of aneurysmal growth and remodeling.

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Section: Methodsmentioning

confidence: 99%

Hemodynamics‐driven deposition of intraluminal thrombus in abdominal aortic aneurysms

Achille

Tellides

Humphrey

2016

Numer Methods Biomed Eng

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“…The final rupture of an AAA is thought to be a result of biologic degradation mediated by the interaction between the arterial wall and hemodynamic forces including, WSS and blood pressure . Previous studies have also indicated that the formation and accumulation of ILTs are associated with hemodynamic features (especially disturbed flow and aberrant WSSs), which influence the mechanical stress of the underlying vessel wall through direct mechanical as well as indirect mechanochemical effects …”

Section: Introductionmentioning

confidence: 99%

“…17 The final rupture of an AAA is thought to be a result of biologic degradation mediated by the interaction between the arterial wall and hemodynamic forces including, WSS and blood pressure. 18,19 Previous studies have also indicated that the formation and accumulation of ILTs are associated with hemodynamic features (especially disturbed flow and aberrant WSSs), 20,21 which influence the mechanical stress of the underlying vessel wall through direct mechanical as well as indirect mechanochemical effects. [22][23][24] The purpose of this study was to computationally simulate aortic blood flow in RAAAs using 13 patient-specific RAAA models that were reconstructed from computed tomography angiography (CTA) images, aiming to investigate how the presence and thickness of ILTs affect the local hemodynamic factors at rupture sites.…”

Section: Introductionmentioning

confidence: 99%

Role of intraluminal thrombus in abdominal aortic aneurysm ruptures: A hemodynamic point of view

et al. 2019

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Purpose Intraluminal thrombus (ILTs) are found in most abdominal aortic aneurysms (AAAs) of clinically relevant size; however, the role of ILTs in AAA ruptures remains unclear. This study investigated the role of the presence and thickness of ILTs in AAA ruptures by analyzing the hemodynamic environment in ruptured AAAs (RAAAs). Methods Three‐dimensional reconstructions from computed tomography scans were performed, and 13 RAAA cases were categorized into a no‐ILT group, a thin‐layered ILT group (thickness < 3 mm), and a thick‐layered ILT group. The hemodynamic features of the RAAAs were assessed using computational fluid dynamics simulation. Results The thin‐ and thick‐layered ILT groups showed significant differences in aneurysm diameters (P < 0.05). The three types of AAAs ruptured at different flow regions, with different hemodynamic features: (a) the no‐ILT AAAs ruptured at regions of flow recirculation where velocity and wall shear stresses (WSSs) were close to zero; (b) the thin‐layered ILT AAAs ruptured at sites at which the dominant flow impinged the wall; and (c) the thick‐layered ILT AAAs ruptured at the border of the dominant flow channel and recirculation zone where the flow velocity and pressure changed dramatically. Conclusions Hemodynamic characteristics influence the rupture mechanisms of particular AAAs differently on the basis of the presence and thickness of ILTs. Recirculation flows and low WSSs may have negative effects by inducing local rupture or positive effects by promoting the formation of thin‐layered ILTs. However, eccentrically located thick‐layered ILTs may increase the rupture risk of small AAAs because of their location in the sac lumen, which results in chaotic flow patterns and rapid increases in flow resistance.

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“…Another potential limitation of the current model is the assumption that luminal area remains constant and concentric throughout the G&R process. Some clinical observations support this assumption of constant luminal diameter in thrombus‐laden aneurysms (eg, Zambrano et al), but this is not universal, especially in smaller lesions. Non‐uniform thrombus deposition is undoubtedly related to the complex evolving haemodynamics, which can vary depending on the location, size, and shape of the lesion.…”

Section: Limitations and Proposed Experimentsmentioning

confidence: 99%

“…Some clinical observations support this assumption of constant luminal diameter in thrombus‐laden aneurysms (eg, Zambrano et al), but this is not universal, especially in smaller lesions. Non‐uniform thrombus deposition is undoubtedly related to the complex evolving haemodynamics, which can vary depending on the location, size, and shape of the lesion. Future studies should explore the added complexities of incorporating a hemodynamically driven evolution of thrombus deposition within an FSG model.…”

Section: Limitations and Proposed Experimentsmentioning

confidence: 99%

Potential biomechanical roles of risk factors in the evolution of thrombus‐laden abdominal aortic aneurysms

Virag

Wilson

Humphrey

et al. 2017

Numer Methods Biomed Eng

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Abdominal aortic aneurysms (AAAs) typically harbour an intraluminal thrombus (ILT), yet most prior computational models neglect biochemomechanical effects of thrombus on lesion evolution. We recently proposed a growth and remodelling model of thrombus-laden AAAs that introduced a number of new constitutive relations and associated model parameters. Because values of several of these parameters have yet to be elucidated by clinical data, and could vary significantly from patient to patient, the aim of this study was to investigate the possible extent to which these parameters influence AAA evolution. Given that some of these parameters model potential effects of factors that influence the risk of rupture, this study also provides insight into possible roles of common risk factors on the natural history of AAAs. Despite geometrical limitations of a cylindrical domain, findings support current thought that smoking, hypertension, and female sex likely increase the risk of rupture. Although thrombus thickness is not a reliable risk factor for rupture, the model suggests that the presence of ILT may have a destabilizing effect on AAA evolution, consistent with histological findings from human samples. Finally, simulations support two hypotheses that should be tested on patient-specific geometries in the future. First, ILT is a potential source of the staccato enlargement observed in many AAAs. Second, ILT can influence rupture risk, positively or negatively, via competing biomechanical (e.g., stress shielding) and biochemical (i.e., proteolytic) effects. Although further computational and experimental studies are needed, the present findings highlight the importance of considering ILT when predicting aneurysmal enlargement and rupture risk.

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Association of Intraluminal Thrombus, Hemodynamic Forces, and Abdominal Aortic Aneurysm Expansion Using Longitudinal CT Images

Cited by 90 publications

References 54 publications

Hemodynamics‐driven deposition of intraluminal thrombus in abdominal aortic aneurysms

Hemodynamics‐driven deposition of intraluminal thrombus in abdominal aortic aneurysms

Role of intraluminal thrombus in abdominal aortic aneurysm ruptures: A hemodynamic point of view

Potential biomechanical roles of risk factors in the evolution of thrombus‐laden abdominal aortic aneurysms

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