Organisers

• Simone Melchionna (Ecole Polytechnique Fédérale de Lausanne, Switzerland)
• Alfio Quarteroni (Ecole Polytechnique Fédérale de Lausanne, Switzerland)
• Efthimios Kaxiras (Ecole Polytechnique Fédérale de Lausanne, Switzerland)

Supports

   ESF-SimBioMa

   CECAM

Description

In recent years there has been an upsurge of interest towards the understanding of

circulation of blood, from capillaries to large systems of vessels. Blood and the vascular system constitute a multi-faceted environment composed of several physical layers and resulting in a complex phenomenology.  Understanding blood rheology within the cardiovascular system has fundamental implications in the biomedical sciences. As well documented, atherosclerosis is the most common disease that affects the arterial blood vessels and coronary heart disease is the most common cause of mortality in western countries.

Nowadays, the simulation of blood flow in complex systems of vessels, such as coronary or cranial arteries, is becoming a standard achievement in several computational groups. However, a correct understanding of blood flows

still requires the inclusion of vascular deformability, physiologically correct inflow and outflow conditions, and physiologically motivated models to emulate the global nature of the cardiovascular system.       

On the other hand, more and more the community is shifting its attention towards the behavior of blood emerging  from its corpuscolar nature, such as in the formation of thrombi, in proximity of stents or aneurisms, or in relation to atherogenesis and the formation and evolution of plaques.

This intention reflects on the need for sophisticated simulation methods that enable the simulation of blood plasma and suspended bodies, possibly allowing for internal deformation. 

Moreover, in order to handle large data sets from real patients and relate the simulation data to the history  of a given disease, there is growing demand for high performance computing. To this purpose, some groups involved in hemodynamics focus many of their efforts in developing highly efficient softwares, on conventional parallel CPUs or

accelerator-based hardware.

Scientific Objectives

The proposed workshop will cover the following topics:  

* The viscous response of bulk blood arises from the interplay of the Newtonian rheology of plasma and  the presence of red blood cells, with the ensuing shear-thinning response and the Farhaeus-Lindqvist effect in pipe flow conditions. It is recognized that inhomogeneities in the red bloood cell organization lie at the heart of such effect, however the current understanding is still unsatisfactory. 

* Handling vascular walls is a crucial factor in the correct modeling of blood circulation, affecting  the interplay between viscous, inertial and centrifugal forces. The inclusion of vessel compliance, vascular semi-rigid movements and vascular remodeling are important components that are not included in most simulation studies.                                          

* Several groups are devoted to the understanding of blood in proximity of the endothelium and at the scale of microns. Here, the flow pattern is affected by the presence of the glycalyx and atheriogenesis is driven by the lipoprotein uptake.                                                   

The aspects related to transmural fluxes, interaction of the fluid flow with the glycocalyx matrix, and cell adhesion properties will be covered.                                                         

* There are several computational fluid dynamics approaches to hemodynamics, such as the numerical solution of the Navier-Stokes equations,  the Lattice Boltzmann method, Multi-Particle Collision dynamics, and so on. In addition, multi-scale methodologies have been proposed in order to study flow pattern with a number of elemental components that cannot be handled by conventional single-scale methods. 

The workshop will critically assess the issues related to each of these methods.                      

* Different computational approaches have been developed to reproduce blood circulation and many results have been obtained. In order to emulate the cardiovascular system globally, one-dimensional closures of fully-fledged three-dimensional approaches have been proposed. The workshop will offer a good opportunity to stimulate a discussion on this topic. 

* Deployment of high-performance computing in the field of hemodynamics.                                

Assessment of available softwares and real-time applications for medical practice.                    

* An effort will be made to attract a few experimentalists, whose input to the computational community would be very useful, and who might also benefit greatly from the interaction  with the computational community.                             

References

Pedley T.J., The fluid mechanics of large blood vessels, Cambridge University Press.

Peskin C., Modeling and simulation in medicine and the life sciences, Springer.

Formaggia L., Quarteroni A., Veneziani, A., Cardiovascular mathematics, Springer.

Westerof N., Stergiopulous N., Noble M.I.M., Snapshots of hemodynamics, Springer.

Weinbaum S. et al., Proc. Natl. Acad. Sci. USA, 100, 7988 (2003)

Damiano E.R., Stace, T.M. Biophys. J., 82, 1153 (2002)

Rybicki F.J. et al., Intl. J. of Cardiovasc. Imaging, 10.1007/s10554-008-9418-x (2009)