Hemodynamic investigation of a patient-specific abdominal aortic aneurysm with iliac artery tortuosity

Qiu, Yue; Yuan, Ding; Wang, Ye; Wen, Jun; Zheng, Tinghui

doi:10.1080/10255842.2018.1522531

Cited by 24 publications

(9 citation statements)

References 26 publications

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“…8). The fundamental role of helical (or swirling flow) in the prevention of thrombosis and disease progression has been confirmed in many literature studies [29][30][31]. In particular, Morbiducci et al [30] also presented an inverse relationship between helical flow and OSI evaluating four bypass geometries in ascending aorta, according to our results.…”

Section: Discussionsupporting

confidence: 81%

Impact of leg bending in the patient-specific computational fluid dynamics of popliteal stenting

et al. 2021

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Endovascular treatment of the femoro-popliteal artery has recently become a valuable therapeutic option for popliteal arterial aneurysms. However, its efficacy remains controversial due to the relatively high rate of complications, such as stent occlusion as result of intra-stent thrombosis. The elucidation of the interplay among vessel geometrical features, local hemodynamics, and leg bending seems crucial to understand onset and progression of popliteal intra-stent thrombosis. To this aim, patient-specific computational fluid dynamic simulations were performed in order to assess the intra-stent hemodynamics of two patients endovascularly treated for popliteal arterial aneurysm by stent-grafts and experiencing intra-stent thrombosis. Both Newtonian and non-Newtonian blood rheological models were considered. Results were presented in terms of tortuosity, luminal area exposed to low (< 0.4 Pa) and high (> 1.5 Pa) time-averaged wall shear stress (TAWSS), area exposed to high (> 0.3) oscillatory shear index (OSI), and flow helicity. Study outcomes demonstrated that leg bending induced significant hemodynamic differences (> 50% increase) in both patients for all the considered variables, except for OSI in one of the two considered patients. In both leg configurations, stent-graft overlapping induced a severe discontinuity of the lumen diameter where the proximal stented zone is characterized by low tortuosity, low velocity, low helicity, low TAWSS, and high OSI; while the distal part has higher tortuosity, velocity, helicity, TAWSS, and lower OSI. Sensitivity study on applied boundary conditions showed that the different inlet velocity profiles for a given inlet waveform affect slightly the numerical solution; conversely, the shape and magnitude of the prescribed inlet waveform is determinant. Focusing on the comparison between the Newtonian and non-Newtonian blood models, the area with low TAWSS is greater in the Newtonian model for both patients, while no significant difference occurs between the surfaces with high TAWSS. GraphicAbstract Patient-specific computational fluid dynamic simulations were performed in order to assess the intra-stent hemodynamics of two patients endovascularly treated for popliteal arterial aneurysm and experiencing intra-stent thrombosis. Both Newtonian and non-Newtonian blood rheological models were considered. In both straight and bent leg configurations, stent-graft overlapping induced a severe discontinuity of the lumen diameter where the proximal stented zone is characterized by low tortuosity, low velocity, low helicity, low time-averaged wall shear stress (TAWSS), and high oscillatory index (OSI); while the distal part has higher tortuosity, velocity, helicity, TAWSS, and lower OSI.

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Section: Discussionsupporting

confidence: 81%

Impact of leg bending in the patient-specific computational fluid dynamics of popliteal stenting

et al. 2021

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“…The kinked morphologies were predominantly in the left CIA and could have stabilised at an early phase of progression because of the proximal angulation of the CIA, creating high wall shear stress throughout the CIAA (similar to the non-aneurysmal contralateral CIA for unilateral cases) and potentially maintaining helical flow in the CIA. 17 These snapshot data cannot provide information as to whether any of these kinked CIAAs would progress to the fusiform variant, although this seems unlikely as it would involve loss of the sharp bend in the proximal CIA if, and when, they enlarge. It is also unclear whether longitudinal remodelling (increasing tortuosity) of the CIA might halt expansive remodelling (dilation).…”

Section: Discussionmentioning

confidence: 98%

Morphology and Computational Fluid Dynamics Support a Novel Classification of Common Iliac Aneurysms

Parker

Powell

Kelsey

et al. 2020

European Journal of Vascular and Endovascular Surgery

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This paper proposes a novel classification of common iliac artery aneurysms (CIAAs), which is relevant to future studies on their prognosis. The groups differed in size, shape, calcification, thrombosis, and haemodynamics. The observations of this study question the applicability of a 35 mm threshold for CIAA repair and explore an alternative that seeks to summarise aneurysm haemodynamics through morphology. This classification has the potential to aid in the risk stratification of CIAA; however; these morphological groups need to be assessed longitudinally and in larger cohorts.Objective: Isolated common iliac artery aneurysms (CIAAs) are uncommon, and evidence concerning their development, progression, and management is weak. The objective was to describe the morphology and haemodynamics of isolated CIAAs in a retrospective study. Methods: Initially, a series of 25 isolated CIAAs (15 intact, 10 ruptured) in 23 patients were gathered from multiple centres, reconstructed from computed tomography, and then morphologically classified and analysed with computational fluid dynamics. The morphological classification was applied in a separate, consecutive cohort of 162 patients assessed for elective aorto-iliac intervention, in which 55 patients had intact CIAAs. Results: In the isolated CIAA cohort, three distinct morphologies were identified: complex (involving a bifurcation); fusiform; and kinked (distal to a sharp bend in the CIA), with mean diameters of 90.3, 48.3, and 31.7 mm, and mean time averaged wall shear stresses of 0.16, 0.31, and 0.71 Pa, respectively (both analysis of variance p values < .001). Kinked cases vs. fusiform cases had less thrombus and favourable haemodynamics similar to the non-aneurysmal contralateral common iliac artery (CIA). Ruptured isolated CIAAs were large (mean diameter 87.5 mm, range 55.5e138.0 mm) and predominantly complex. The mean CIA length for aneurysmal arteries was greatest in kinked cases followed by complex and fusiform (100.8 mm, 91.1 mm, and 80.6 mm, respectively). The morphological classification was readily applicable to a separate elective patient cohort. Conclusion:A new morphological categorisation of CIAAs is proposed. Potentially this is associated with both haemodynamics and clinical course. Further research is required to determine whether the kinked CIAA is protected haemodynamically from aneurysm progression and to establish the wider applicability of the categorisation presented.

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“…If there is a deviation from the physiological state, the elevated pressure drop will result in disordered blood flow ( Raptis et al, 2017a ), such as that in the sac of AAA. Because the pressure drop increases significantly, there will be irregular turbulence and eddy currents will form ( Qiu et al, 2018 ). In addition, after intravascular repair, a higher pressure drop in the stent will lead to increased loss of kinetic energy of blood flow through the stent, which in turn affects distal lower extremity vascular perfusion.…”

Section: Discussionmentioning

confidence: 99%

A Comparative Study on the Hemodynamic Performance Within Cross and Non-cross Stent-Grafts for Abdominal Aortic Aneurysms With an Angulated Neck

et al. 2021

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Objectives: Cross-limb stent grafts for endovascular aneurysm repair (EVAR) are often employed for abdominal aortic aneurysms (AAAs) with significant aortic neck angulation. Neck angulation may be coronal or sagittal; however, previous hemodynamic studies of cross-limb EVAR stent grafts (SGs) primarily utilized simplified planar neck geometries. This study examined the differences in flow patterns and hemodynamic parameters between crossed and non-crossed limb SGs at different spatial neck angulations.Methods: Ideal models consisting of 13 cross and 13 non-cross limbs were established, with coronal and sagittal angles ranging from 0 to 90°. Computational fluid dynamics (CFD) was used to capture the hemodynamic information, and the differences were compared.Results: With regards to the pressure drop index, the maximum difference caused by the configuration and angular direction was 4.6 and 8.0%, respectively, but the difference resulting from the change in aneurysm neck angle can reach 27.1%. With regards to the SAR-TAWSS index, the maximum difference caused by the configuration and angular direction was 7.8 and 9.8%, respectively, but the difference resulting from the change in aneurysm neck angle can reach 26.7%. In addition, when the aneurysm neck angle is lower than 45°, the configuration and angular direction significantly influence the OSI and helical flow intensity index. However, when the aneurysm neck angle is greater than 45°, the hemodynamic differences of each model at the same aneurysm neck angle are reduced.Conclusion: The main factor affecting the hemodynamic index was the angle of the aneurysm neck, while the configuration and angular direction had little effect on the hemodynamics. Furthermore, when the aneurysm neck was greatly angulated, the cross-limb technique did not increase the risk of thrombosis.

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Hemodynamic investigation of a patient-specific abdominal aortic aneurysm with iliac artery tortuosity

Cited by 24 publications

References 26 publications

Impact of leg bending in the patient-specific computational fluid dynamics of popliteal stenting

Impact of leg bending in the patient-specific computational fluid dynamics of popliteal stenting

Morphology and Computational Fluid Dynamics Support a Novel Classification of Common Iliac Aneurysms

A Comparative Study on the Hemodynamic Performance Within Cross and Non-cross Stent-Grafts for Abdominal Aortic Aneurysms With an Angulated Neck

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