ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

FROM PATIENT-SPECIFIC DATA TO MULTISCALE
HEMODYNAMICS SIMULATIONS: THE CHALLENGE OF
BOUNDARY CONDITIONS
I. Vignon-Clementel 1 , G. Arbia 1 , A. Baretta 2 , C. Corsini 2 , M.E. Moghadam 3 , G.
Troianowski 4 , W. Yang 3 , J. Feinstein 4 , T.Y. Hsia 5 , A. Marsden 3 , F. Migliavacca 2 , G.
Pennati 2 , and The Modeling of Congenital Hearts Alliance (MOCHA) Investigators
1. ABSTRACT
Computer fluid dynamics is now a common tool to explore hemodynamics in patientspecific
simulations, either to better understand a specific physiopathology, explore
several physiological states or to create a representative hemodynamics model
preoperatively to explore several virtual surgical options. In this context, the
specification of boundary conditions is key because pressure and flow within the
modeled domain are driven by the interplay between geometry (form) and
hemodynamics boundary conditions (function). However, these boundary conditions are
rarely the measured variables. We thus show how one can go from patient-specific
clinical data (MRI and catheterization) to simulation input parameters, including
modeling assumptions and the impact of both on simulation results. To take into
account the rest of the circulation outside of the three-dimensional modeled domain, a
number of reduced order models exist. We explain how Windkessel models and more
involved lumped parameter models can be calibrated, and discuss their predictive
aspects. The specification of boundary conditions in patient-specific simulations can
also create numerical challenges for which recent developments are explained.
Applications include preoperative modeling and virtual surgical options in the Fontan
palliation of single ventricle congenital heart disease, under rest and exercise.
2. INTRODUCTION
Computer fluid dynamics is now a common tool to explore hemodynamics in patientspecific
simulations. Blood flow in the larger vessels is highly three-dimensional and
modeled by 3D Navier-Stokes equations (3DNS). In this context, the specification of
boundary conditions is key because pressure and flow within the modeled domain are
driven by the interplay between geometry (form) and hemodynamics boundary
conditions (function), and thus must be modeled with care [1]. In the next section, we
therefore present a summary of our work done in the coupling of more detailed models
(3DNS) with reduced models of the rest of the circulation, including how to address
numerical instabilities in the presence of backflow and to devise reduced-models that
take into account patient-specific pressure and flow measurements. The results section
features applications to multi-stage Fontan palliation of single ventricle congenital heart
disease. Examples are given of how such tools allow to study a specific
1 INRIA, France; 2 Politecnico di Milano, Italy; 3 UCSD, USA; 4 Stanford University,
USA; 5 Great Ormond Street Hospital for Children, UK