A computational fluid dynamics model for the aortic valve in the context of the Ross procedure

2021
Domain : Computational Fluid Dynamics, Numerical Modeling of Cardiovascular flows, Fluid-Structure Interaction
Starting date : September 2021
Deadline to apply : 10/07/2020 / Note: Applications made after the deadline will not be considered

Thesis supervisors
  • Julien Favier, Pr. M2P2 lab, Aix Marseille University, CNRS, Centrale Marseille
  • Loic Macé, PU-PH at La Timone Hospital, M2P2 lab, Aix Marseille University, CNRS, Centrale Marseille
How to apply : send a CV and a cover letter to: Julien.Favier@m2p2.fr, Loic.Mace@ap-hm.fr, Marien.Lenoir@ap-hm.fr
The aortic root is at the core of many heart diseases and a subject of medical research which has been increasing rapidly since the last decade, as evidenced by the growing number of studies and surgical techniques to repair or replace the aortic valve. This aortic valve by a mechanism complex opening / closing based on three sigmoidal cusps, ensures a unidirectional flow. To progress in the understanding of the biomechanics of the aortic valve, a global approach integrating patient data (DICOM angioscanners), and numerical simulation of unsteady mechanisms of fluid-structure interaction is now necessary.

The purpose of this PhD 

is to use numerical simulation of the hemodynamics of the aortic valve in the specific case of the Ross procedure, which consists in replacing the aortic valve by the patient’s own pulmonary valve. Despite well-identified advantages of this surgery operation in terms of quality-of-life improvements, long-term post-surgery issues still need to be characterized and better understood in a large context involving both clinical aspects, hemodynamics and biomechanical properties of the valve. The unsteady velocity and pressure fields of blood within one and many cardiac cycles, as well as the wall shear stress distributions in pathological conditions will be analyzed to improve the current operative techniques of surgical replacement of the aortic valve in the context of the Ross procedure.
A dedicated numerical simulation tool will be used, based on the numerical methods developed at M2P2 in the context of the numerical simulation of complex geometries immersed in biological fluids (Immersed boundary methods and lattice Boltzmann method). This thesis will be performed between the medical-surgical pediatric and congenital cardiology of the Timone (AP-HM) and the laboratory of Mechanics Modeling (M2P2, UMR CNRS) Aix Marseille University. Close interactions with experts in numerical simulations and surgeons (working at M2P2 and AP-HM) are expected.

Expected profile of the candidate

The candidate will have a solid background in fluid mechanics, computational fluid dynamics and possibly fluid-structure interaction. An experience on the physical analysis of generic mechanisms involved in fluid-structure interaction would be a strong asset. Having a taste for health issues and biomedical themes or having already worked in that context would be greatly appreciated. Although a large part of the code coupling fluid and structure will be almost available, minor numerical developments are to be expected.

References :
A non-staggered coupling of finite element and lattice Boltzmann methods via an immersed boundary scheme for fluid-structure interaction. Li Z. & Favier J. Computers and Fluids, Vol. 143, pp. 90-102, 2017.
An improved explicit immersed boundary method to couple with lattice Boltzmann model for singleand multi- component fluid flows. Li, Z., Favier, J., D’Ortona, U. & Poncet, S. J. Comput. Phys. 304, 424–440, 2016.
A coupled Immersed Boundary - Lattice Boltzmann method for incompressible flows through porous media. Pepona M. & Favier J. Journal of Computational Physics, Vol. 321, pp. 1170-1184, 2016.
Cryopreserved homograft in the Ross procedure: outcomes and prognostic factors. Kalfa D, Feier H, Loundou A, Fraisse A, Macé L, Metras D, Kreitmann B. J Heart Valve Dis. 2011;20(5):571-81.
How to choose the best available homograft to reconstruct the right ventricular outflow tract. Kalfa D, Macé L, Metras D, Kreitmann B. J Thorac Cardiovasc Surg. 201;142(4):950-3.
Pulmonary position cryopreserved homograft in non-Ross patients: how to improve the results? Kalfa DM, Loundou A, Nouaille de Gorce Y, Fraisse A, Metras DR, Macé L, Kreitmann B. Eur J Cardiothorac Surg. 2012; 42(6):981-7.
Biomechanical and morphological remodeling of the autograft root after the Ross procedure in aortic stenosis versus regurgitation: an MRI study. Lenoir M, & al. American Association for Thoracic Surgery: communication - Aortic Summit New York. 1-16, 2018.