Abdominal aortic aneurysms (AAAs) are currently treated based on the universal maximum diameter criterion, but other geometric variables may play a role in the risk of rupture. The hemodynamic environment inside the AAA sac has been shown to interact with several biologic processes which can affect prognosis. AAA geometric configuration has a significant impact in the hemodynamic conditions that develop, which has only been recently realized, with implications for rupture risk estimations. We aim to perform a parametric study to evaluate the effect of aortic neck angulation, angle between the iliac arteries, and sac asymmetry (SA) on the hemodynamic variables of AAAs.
This study uses idealized AAA models and it is parametrized in terms of 3 quantities as follows: the neck angle, φ (°), iliac angle, θ (°), and SA (%), each of which accepts 3 different values, specifically φ = (0°, 30°, 60°), θ = (40°, 60°, 80°), and SA = (S, °SS, °OS), where the SA can either be on the same side with respect to neck (SS) or on the opposite side (OS). Time average wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), and the velocity profile are calculated for different geometric configurations, while the percentage of the total surface area under thrombogenic conditions, using thresholds previously reported in the literature, is also recorded.
In case of an angulated neck and a higher angle between iliac arteries, favorable hemodynamic conditions are predicted with higher TAWSS and lower OSI and RRT values. The area under thrombogenic conditions reduces by 16–46% as the neck angle increases from 0° to 60°, depending on the hemodynamic variable under consideration. The effect of iliac angulation is present but less pronounced with 2.5–7.5% change between the lower and the higher angle. The effect of SA seems to be significant for OSI, with a nonsymmetrical configuration being hemodynamically favorable, which in the presence of an angulated neck is more pronounced for the OS outline.
Favorable hemodynamic conditions develop inside the sac of idealized AAAs with increasing neck and iliac angles. Regarding the SA parameter, asymmetrical configurations most often appear advantageous. Concerning the velocity profile the triplet (φ, θ, SA) may affect outcomes under certain conditions and thus should be taken into account when parametrizing the geometric characteristics of AAAs.
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- Editor's choice - European Society for Vascular Surgery (ESVS) 2019 clinical practice guidelines on the management of abdominal aorto-iliac artery aneurysms.Eur J Vasc Endovasc Surg. 2019 Jan; 57 (Erratum in: Eur J Vasc Endovasc Surg. 2020 Mar;59(3):494.): 8-93
- Endovascular strategy or open repair for ruptured abdominal aortic aneurysm: one-year outcomes from the IMPROVE randomized trial.Eur Heart J. 2015; 36: 2061-2069
- Endovascular repair or open repair for ruptured abdominal aortic aneurysm: a Cochrane systematic review.BMJ Open. 2016; 6: e008391
- Advancements in identifying biomechanical determinants for abdominal aortic aneurysm rupture.Vascular. 2015; 23: 65-77
- New approaches to abdominal aortic aneurysm rupture risk assessment: engineering insights with clinical gain.Arterioscler Thromb Vasc Biol. 2010; 30: 1687-1694
- Intraluminal thrombus: innocent bystander or factor in abdominal aortic aneurysm pathogenesis?.JVS Vasc Sci. 2021; 2: 159-169
- Intraluminal abdominal aortic aneurysm thrombus is associated with disruption of wall integrity.J Vasc Surg. 2013; 57: 77-83
- Association of intraluminal thrombus in abdominal aortic aneurysm with local hypoxia and wall weakening.J Vasc Surg. 2001; 34: 291-299
- The effect of angulation in abdominal aortic aneurysms: fluid-structure interaction simulations of idealized geometries.Med Biol Eng Comput. 2010; 48: 1175-1190
- A robust approach for exploring hemodynamics and thrombus growth associations in abdominal aortic aneurysms.Med Biol Eng Comput. 2017; 55: 1493-1506
- Accounting for residence-time in blood rheology models: do we really need non-Newtonian blood flow modelling in large arteries?.J R Soc Interf. 2018; 15: 20180486
- Effects of the non-Newtonian viscosity of blood on flows in a diseased arterial vessel. Part 1: steady flows.Biorheology. 1991; 28: 241-262
- Hemodynamic analysis in an idealized artery tree: differences in wall shear stress between Newtonian and non-Newtonian blood models.PLoS One. 2015; 10: e0124575
- Effect of non-Newtonian behavior on hemodynamics of cerebral aneurysms.J Biomech Eng. 2009; 9: 131
- The fluid mechanics of large blood vessels.Cambridge University Press, Cambridge, UK1980
- Numerical simulation and experimental validation of blood flow in arteries with structured-tree outflow conditions.Ann Biomed Eng. 2000; 28: 1281-1299
- Should the proximal part of a bifurcated aortic graft be kept as short as possible? A computational study elucidates on aortic graft hemodynamics for various main body lengths.Ann Vasc Surg. 2022; 84: 344-353
- Advances in determining abdominal aortic aneurysm size and growth.World J Radiol. 2016; 8: 148-158
- The - not so - solid 5.5 cm threshold for abdominal aortic aneurysm repair: facts, misinterpretations, and future directions.Front Surg. 2016; 3: 1
- Patient-specific computational fluid dynamics: structured mesh generation from coronary angiography.Med Biol Eng Comput. 2010; 48: 371-380
- Pulsatile flow in the human left coronary artery bifurcation: average conditions.J Biomech Eng. 1996; 118: 74-82
- Spatial comparison between wall shear stress measures and porcine arterial endothelial permeability.Am J Physiol Heart Circ Physiol. 2004; 286: H1916-H1922
- Hemodynamic shear stress and its role in atherosclerosis.JAMA. 1999; 282: 2035-2042
- Quantitative analysis of bulk flow in imagebased hemodynamic models of the carotid bifurcation: the influence of outflow conditions as test case.Ann Biomed Eng. 2010; 38: 3688-3705
- Perspective: a method for uniform reporting of grid refinement studies.J Fluids Eng. 1994; 116: 405-413
- Haemodynamics and stresses in abdominal aortic aneurysms: a fluid-structure interaction study into the effect of proximal neck and iliac bifurcation angle.J Biomech. 2017; 60: 150-156
- Effect of intraluminal thrombus asymmetrical deposition on abdominal aortic aneurysm growth rate.J Endovasc Ther. 2015; 22: 406-412
- Analysis of morphological and hemodynamical indexes in abdominal aortic aneurysms as preliminary indicators of intraluminal thrombus deposition.Biomech Model Mechanobiol. 2020; 19: 1035-1053
- A longitudinal comparison of hemodynamics and intraluminal thrombus deposition in abdominal aortic aneurysms.Am J Physiol Heart Circ Physiol. 2014; 307: H1786-H1795
- Hemodynamics of the normal aorta compared to fusiform and saccular abdominal aortic aneurysms with emphasis on a potential thrombus formation mechanism.Ann Biomed Eng. 2010; 38: 380-390
- The mechanical role of thrombus on the growth rate of an abdominal aortic aneurysm.J Vasc Surg. 2010; 51: 19-26
- Local diameter, wall stress, and thrombus thickness influence the local growth of abdominal aortic aneurysms.J Endovasc Ther. 2016; 23: 957-966
- Size and location of thrombus in intact and ruptured abdominal aortic aneurysms.J Vasc Surg. 2005; 41: 584-588
- Thrombus volume is associated with cardiovascular events and aneurysm growth in patients who have abdominal aortic aneurysms.J Vasc Surg. 2011; 53: 28-35
- Mural thrombus and the progression of abdominal aortic aneurysms: a large population-based prospective cohort study.Eur J Vasc Endovasc Surg. 2014; 48: 301-307
- Low wall shear stress predominates at sites of abdominal aortic aneurysm rupture.J Vasc Surg. 2016; 63: 1613-1619
- Combined curvature and wall shear stress analysis of abdominal aortic aneurysm: an analysis of rupture risk factors.Cardiovasc Intervent Radiol. 2022; 45: 752-760
- Biomechanical changes during abdominal aortic aneurysm growth.PLoS One. 2017; 12: e0187421
Published online: March 01, 2023
Accepted: February 14, 2023
Received: November 10, 2022
Publication stageIn Press Journal Pre-Proof
Conflict of interest: None.
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