Ifsttar PhD subject

French version
Detailed form :

Title : Influence of the blood flow and fluid structure interaction in simulation of abdominal aortic traumatic rupture

Main host Laboratory - Referent Advisor   -

Director of the main host Laboratory   -

PhD Speciality Biomécanique

Axis of the performance contract 1 - COP2017 - Efficient transport and safe travel

Main location Marseille

Doctoral affiliation AIX-MARSEILLE UNIVERSITE

PhD school SCIENCES DU MOUVEMENT HUMAIN (SMH)

Planned PhD supervisor BEHR Michel  -  Université Gustave Eiffel  -  LBA

Planned financing Contrat doctoral  - Ifsttar

Abstract

Context and Objectives:
15% of the car crash victims have a traumatic aortic rupture in the 24 hours following the accident [1]. Currently, aortic assessment criteria are based on aortic diameter by CT scan or MRI. A recent study compared the different morphologies of the ruptured aorta in case of traumatic injuries and aneurismal pathologies [2]. This last study showed that the aortic diameters, the distance between celiac artery and carotids, the distance between main left coronary and common left carotid are higher in aneurismal patients which implies an averaged geometry for traumatic patients. However the inter-individual variability is significant, mainly due to the variation of the aortic morphology with age.
The influence of hydrodynamic aspects in the aortic traumatic rupture is debated : some authors hypothesized that the structural alteration of the aorta is the only cause of rupture [3], [4] while others authors offered indices based on pressure. The rupture mechanism related to the flow influence appears as secondary to the structural mechanism. However in non-traumatic aortic dissection, the influence of the flow has been highlighted by imaging technics with computation of the wall shear stresses and proof of degeneration through histology [5]. Moreover, analysis of the flow pattern in the aorta as well as the influence of aortic geometry have been assessed mainly as relative to age [6] and were limited to wall shear stress analysis which was not sufficient in case of traumatic rupture (as no long term alteration occurs). The interactions between blood and aortic wall have to be taken into consideration more especially in case of impaction while over pressure phenomenon is implied. The hypothesis of this work is the flow in traumatic rupture should not be only consider as the internal pressure of the aorta but that the flow patterns during the impaction also play a significant part in rupture.
Recent works of our laboratory and currently under publication have been focusing on the necessity to take the cardiac cycle into consideration in traumatic aortic injuries. They showed the necessity to the kinematics of the flow in impaction simulations [7]. This PhD subject follows the previous work of M. W. Wei in which a specific model of the aortic injury has been developed and validated using LS Dyna in which the internal pressure is taken into consideration.
To the best of our knowledge, there is currently only one aortic model usable for traumatic situations and taking into account the fluid structure interaction. This model is however limited to the hydrostatic conditions [8]. The study of the fluid behaviour during the impaction is limited apart from the pressure influence as previously mentioned. Experimentally, the main simulations have been performed on aortic aneurism rather than on dissection or rupture [9], [10]. The link between aneurismal rupture and wall shear stress threshold is complex: in the aneurism, areas where wall shear stress is found higher are not the one where the aneurism breaks.
Validations of such models are still limited. On one side, experimental model do not consider anatomical and hemodynamic specificity of the patient. On the other side, ex-vivo and in-vitro model are limited to available characteristics of the subjects (age of the cadavers, material properties) and by the methods used for conservation or experimental set ups.
Realism of the numeric simulation consist in : (1) the knowledge of the variability between patients of different morphology of the aortic anatomy and of its influence on flow, and (2) the knowledge of the physiological (and heathy) flow patterns of the aorta before rupture, pressure simulation and high velocities in aorta.
Using the 3D+t phase contrast by magnetic resonance imaging [11], [12] will enable the validation of the flow in physiological conditions [5], [13]. To simulate the influence of different cardiac cycle timing with a pulsed flow will enable a better consideration of fluid-structure interaction during the accident.
Objective of this PhD work is to quantify the possible influence of the flow in the mechanism of the aortic rupture in road accidents. This objective will be reached through two tasks: 1) to physiologically model of the healthy flow in different morpho-types, and 2) to model the injury including physiological model coupled to a sensitivity analysis on real road accidents of aortic rupture.
Link with “unifying projects” of Ifsttar :
The laboratory is involved into one unifying project and one i-site project (Voyageur virtuel et i-Safe), both from the TS2 department.
Regarding the Virtual Traveller, this project includes simulation of the physiology in road injuries and will then contribute to the unifying project (to be validated with the principal investigator of the project). Taking into account the physiological flow and implementing injury criteria related to haemorrhagic risk in Virtual traveller are necessary questions to be addressed. For the i-site project « i-Safe », the sensitivity analysis of the situation of aortic rupture will contribute to the predictive capacity of the model in adding to the modelling databases planed for such project.
Link with the incentive project:
La Taking into account the physiology through fluid-structure interaction is part of an incentive project submitted in 2017. Oriented on the cerebro-spinal fluid, this project will enable to develop fluid indices and numerical simulation with FSI as well as MRI and experimental data for validation.

Bibliography:
[1] N. Fox et al., « Evaluation and management of blunt traumatic aortic injury: a practice management guideline from the Eastern Association for the Surgery of Trauma », J. Trauma Acute Care Surg., vol. 78, no 1, p. 136‑146, janv. 2015.
[2] I. Busscher, J. J. W. Ploegmakers, G. J. Verkerke, et A. G. Veldhuizen, « Comparative anatomical dimensions of the complete human and porcine spine », Eur. Spine J., vol. 19, no 7, p. 1104‑1114, juill. 2010.
[3] J. Forman, S. Stacey, J. Evans, et R. Kent, « Posterior acceleration as a mechanism of blunt traumatic injury of the aorta », J. Biomech., vol. 41, no 6, p. 1359‑1364, 2008.
[4] W. N. Hardy et al., « Mechanisms of traumatic rupture of the aorta and associated peri-isthmic motion and deformation », Stapp Car Crash J., vol. 52, p. 233‑265, nov. 2008.
[5] P. van Ooij et al., « Age-related changes in aortic 3D blood flow velocities and wall shear stress: Implications for the identification of altered hemodynamics in patients with aortic valve disease », J. Magn. Reson. Imaging JMRI, vol. 43, no 5, p. 1239‑1249, mai 2016.
[6] A. R. Bond, S. Iftikhar, A. A. Bharath, et P. D. Weinberg, « Morphological evidence for a change in the pattern of aortic wall shear stress with age », Arterioscler. Thromb. Vasc. Biol., vol. 31, no 3, p. 543‑550, mars 2011.
[7] W. Wei, M. Behr, et C. J. F. Kahn, « The Aorta‐Heart System Finite Element Modelling with Fluid‐Structure Interaction Methods and Validation against Blood Hydrodynamics », in IRCOBI Conference Proceedings, 2016.
[8] J. H. Siegel, A. Belwadi, J. A. Smith, C. Shah, et K. Yang, « Analysis of the mechanism of lateral impact aortic isthmus disruption in real-life motor vehicle crashes using a computer-based finite element numeric model: with simulation of prevention strategies », J. Trauma, vol. 68, no 6, p. 1375‑1395, juin 2010.
[9] V. Deplano, Y. Knapp, E. Bertrand, et E. Gaillard, « Flow behaviour in an asymmetric compliant experimental model for abdominal aortic aneurysm », J. Biomech., vol. 40, no 11, p. 2406‑2413, janv. 2007.
[10] C.-Y. Chen, R. Antón, M. Hung, P. Menon, E. A. Finol, et K. Pekkan, « Effects of Intraluminal Thrombus on Patient-Specific Abdominal Aortic Aneurysm Hemodynamics via Stereoscopic Particle Image Velocity and Computational Fluid Dynamics Modeling », J. Biomech. Eng., vol. 136, no 3, p. 0310011‑0310019, mars 2014.
[11] R. E. Clough, M. Waltham, D. Giese, P. R. Taylor, et T. Schaeffter, « A new imaging method for assessment of aortic dissection using four-dimensional phase contrast magnetic resonance imaging », J. Vasc. Surg., vol. 55, no 4, p. 914‑923, avr. 2012.
[12] D. Dillon-Murphy, A. Noorani, D. Nordsletten, et C. A. Figueroa, « Multi-modality image-based computational analysis of haemodynamics in aortic dissection », Biomech. Model. Mechanobiol., vol. 15, no 4, p. 857‑876, août 2016.
[13] P. van Ooij, A. L. Powell, W. V. Potters, J. C. Carr, M. Markl, et A. J. Barker, « Reproducibility and interobserver variability of systolic blood flow velocity and 3D wall shear stress derived from 4D flow MRI in the healthy aorta », J. Magn. Reson. Imaging JMRI, vol. 43, no 1, p. 236‑248, janv. 2016.

Keywords : Biomechanics, Aortic injuries, blood flow, fluid structure interactions, car accident cases

Main host Laboratory - Referent Advisor	-
Director of the main host Laboratory	-
PhD Speciality	Biomécanique
Axis of the performance contract	1 - COP2017 - Efficient transport and safe travel
Main location	Marseille
Doctoral affiliation	AIX-MARSEILLE UNIVERSITE
PhD school	SCIENCES DU MOUVEMENT HUMAIN (SMH)
Planned PhD supervisor	BEHR Michel - Université Gustave Eiffel - LBA
Planned financing	Contrat doctoral - Ifsttar
Abstract Context and Objectives: 15% of the car crash victims have a traumatic aortic rupture in the 24 hours following the accident [1]. Currently, aortic assessment criteria are based on aortic diameter by CT scan or MRI. A recent study compared the different morphologies of the ruptured aorta in case of traumatic injuries and aneurismal pathologies [2]. This last study showed that the aortic diameters, the distance between celiac artery and carotids, the distance between main left coronary and common left carotid are higher in aneurismal patients which implies an averaged geometry for traumatic patients. However the inter-individual variability is significant, mainly due to the variation of the aortic morphology with age. The influence of hydrodynamic aspects in the aortic traumatic rupture is debated : some authors hypothesized that the structural alteration of the aorta is the only cause of rupture [3], [4] while others authors offered indices based on pressure. The rupture mechanism related to the flow influence appears as secondary to the structural mechanism. However in non-traumatic aortic dissection, the influence of the flow has been highlighted by imaging technics with computation of the wall shear stresses and proof of degeneration through histology [5]. Moreover, analysis of the flow pattern in the aorta as well as the influence of aortic geometry have been assessed mainly as relative to age [6] and were limited to wall shear stress analysis which was not sufficient in case of traumatic rupture (as no long term alteration occurs). The interactions between blood and aortic wall have to be taken into consideration more especially in case of impaction while over pressure phenomenon is implied. The hypothesis of this work is the flow in traumatic rupture should not be only consider as the internal pressure of the aorta but that the flow patterns during the impaction also play a significant part in rupture. Recent works of our laboratory and currently under publication have been focusing on the necessity to take the cardiac cycle into consideration in traumatic aortic injuries. They showed the necessity to the kinematics of the flow in impaction simulations [7]. This PhD subject follows the previous work of M. W. Wei in which a specific model of the aortic injury has been developed and validated using LS Dyna in which the internal pressure is taken into consideration. To the best of our knowledge, there is currently only one aortic model usable for traumatic situations and taking into account the fluid structure interaction. This model is however limited to the hydrostatic conditions [8]. The study of the fluid behaviour during the impaction is limited apart from the pressure influence as previously mentioned. Experimentally, the main simulations have been performed on aortic aneurism rather than on dissection or rupture [9], [10]. The link between aneurismal rupture and wall shear stress threshold is complex: in the aneurism, areas where wall shear stress is found higher are not the one where the aneurism breaks. Validations of such models are still limited. On one side, experimental model do not consider anatomical and hemodynamic specificity of the patient. On the other side, ex-vivo and in-vitro model are limited to available characteristics of the subjects (age of the cadavers, material properties) and by the methods used for conservation or experimental set ups. Realism of the numeric simulation consist in : (1) the knowledge of the variability between patients of different morphology of the aortic anatomy and of its influence on flow, and (2) the knowledge of the physiological (and heathy) flow patterns of the aorta before rupture, pressure simulation and high velocities in aorta. Using the 3D+t phase contrast by magnetic resonance imaging [11], [12] will enable the validation of the flow in physiological conditions [5], [13]. To simulate the influence of different cardiac cycle timing with a pulsed flow will enable a better consideration of fluid-structure interaction during the accident. Objective of this PhD work is to quantify the possible influence of the flow in the mechanism of the aortic rupture in road accidents. This objective will be reached through two tasks: 1) to physiologically model of the healthy flow in different morpho-types, and 2) to model the injury including physiological model coupled to a sensitivity analysis on real road accidents of aortic rupture. Link with “unifying projects” of Ifsttar : The laboratory is involved into one unifying project and one i-site project (Voyageur virtuel et i-Safe), both from the TS2 department. Regarding the Virtual Traveller, this project includes simulation of the physiology in road injuries and will then contribute to the unifying project (to be validated with the principal investigator of the project). Taking into account the physiological flow and implementing injury criteria related to haemorrhagic risk in Virtual traveller are necessary questions to be addressed. For the i-site project « i-Safe », the sensitivity analysis of the situation of aortic rupture will contribute to the predictive capacity of the model in adding to the modelling databases planed for such project. Link with the incentive project: La Taking into account the physiology through fluid-structure interaction is part of an incentive project submitted in 2017. Oriented on the cerebro-spinal fluid, this project will enable to develop fluid indices and numerical simulation with FSI as well as MRI and experimental data for validation. Bibliography: [1] N. Fox et al., « Evaluation and management of blunt traumatic aortic injury: a practice management guideline from the Eastern Association for the Surgery of Trauma », J. Trauma Acute Care Surg., vol. 78, no 1, p. 136‑146, janv. 2015. [2] I. Busscher, J. J. W. Ploegmakers, G. J. Verkerke, et A. G. Veldhuizen, « Comparative anatomical dimensions of the complete human and porcine spine », Eur. Spine J., vol. 19, no 7, p. 1104‑1114, juill. 2010. [3] J. Forman, S. Stacey, J. Evans, et R. Kent, « Posterior acceleration as a mechanism of blunt traumatic injury of the aorta », J. Biomech., vol. 41, no 6, p. 1359‑1364, 2008. [4] W. N. Hardy et al., « Mechanisms of traumatic rupture of the aorta and associated peri-isthmic motion and deformation », Stapp Car Crash J., vol. 52, p. 233‑265, nov. 2008. [5] P. van Ooij et al., « Age-related changes in aortic 3D blood flow velocities and wall shear stress: Implications for the identification of altered hemodynamics in patients with aortic valve disease », J. Magn. Reson. Imaging JMRI, vol. 43, no 5, p. 1239‑1249, mai 2016. [6] A. R. Bond, S. Iftikhar, A. A. Bharath, et P. D. Weinberg, « Morphological evidence for a change in the pattern of aortic wall shear stress with age », Arterioscler. Thromb. Vasc. Biol., vol. 31, no 3, p. 543‑550, mars 2011. [7] W. Wei, M. Behr, et C. J. F. Kahn, « The Aorta‐Heart System Finite Element Modelling with Fluid‐Structure Interaction Methods and Validation against Blood Hydrodynamics », in IRCOBI Conference Proceedings, 2016. [8] J. H. Siegel, A. Belwadi, J. A. Smith, C. Shah, et K. Yang, « Analysis of the mechanism of lateral impact aortic isthmus disruption in real-life motor vehicle crashes using a computer-based finite element numeric model: with simulation of prevention strategies », J. Trauma, vol. 68, no 6, p. 1375‑1395, juin 2010. [9] V. Deplano, Y. Knapp, E. Bertrand, et E. Gaillard, « Flow behaviour in an asymmetric compliant experimental model for abdominal aortic aneurysm », J. Biomech., vol. 40, no 11, p. 2406‑2413, janv. 2007. [10] C.-Y. Chen, R. Antón, M. Hung, P. Menon, E. A. Finol, et K. Pekkan, « Effects of Intraluminal Thrombus on Patient-Specific Abdominal Aortic Aneurysm Hemodynamics via Stereoscopic Particle Image Velocity and Computational Fluid Dynamics Modeling », J. Biomech. Eng., vol. 136, no 3, p. 0310011‑0310019, mars 2014. [11] R. E. Clough, M. Waltham, D. Giese, P. R. Taylor, et T. Schaeffter, « A new imaging method for assessment of aortic dissection using four-dimensional phase contrast magnetic resonance imaging », J. Vasc. Surg., vol. 55, no 4, p. 914‑923, avr. 2012. [12] D. Dillon-Murphy, A. Noorani, D. Nordsletten, et C. A. Figueroa, « Multi-modality image-based computational analysis of haemodynamics in aortic dissection », Biomech. Model. Mechanobiol., vol. 15, no 4, p. 857‑876, août 2016. [13] P. van Ooij, A. L. Powell, W. V. Potters, J. C. Carr, M. Markl, et A. J. Barker, « Reproducibility and interobserver variability of systolic blood flow velocity and 3D wall shear stress derived from 4D flow MRI in the healthy aorta », J. Magn. Reson. Imaging JMRI, vol. 43, no 1, p. 236‑248, janv. 2016.
Keywords :	Biomechanics, Aortic injuries, blood flow, fluid structure interactions, car accident cases

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