Article

# Patient-specific mean pressure drop in the systemic arterial tree, a comparison between 1-D and 3-D models.

Laboratory of Hemodynamics and Cardiovascular Technology, Ecole Polytechnique Fédérale de Lausanne, Switzerland. Electronic address: .

Journal of biomechanics (Impact Factor: 2.66). 08/2012; 45(15):2499-505. DOI: 10.1016/j.jbiomech.2012.07.020 Source: PubMed

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**ABSTRACT:**3D computational fluid dynamics (CFD) in patient-specific geometries provides complementary insights to clinical imaging, to better understand how heart disease, and the side effects of treating heart disease, affect and are affected by hemodynamics. This information can be useful in treatment planning for designing artificial devices that are subject to stress and pressure from blood flow. Yet, these simulations remain relatively costly within a clinical context. The aim of this work is to reduce the complexity of patient-specific simulations by combining image analysis, computational fluid dynamics and model order reduction techniques. The proposed method makes use of a reference geometry estimated as an average of the population, within an efficient statistical framework based on the currents representation of shapes. Snapshots of blood flow simulations performed in the reference geometry are used to build a POD (Proper Orthogonal Decomposition) basis, which can then be mapped on new patients to perform reduced order blood flow simulations with patient specific boundary conditions. This approach is applied to a data-set of 17 tetralogy of Fallot patients to simulate blood flow through the pulmonary artery under normal (healthy or synthetic valves with almost no backflow) and pathological (leaky or absent valve with backflow) conditions to better understand the impact of regurgitated blood on pressure and velocity at the outflow tracts. The model reduction approach is further tested by performing patient simulations under exercise and varying degrees of pathophysiological conditions based on reduction of reference solutions (rest and medium backflow conditions respectively).Medical image analysis 09/2013; 18(1):63-82. · 3.09 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**In this work we employ integer- and fractional-order viscoelastic models in a one-dimensional blood flow solver, and study their behavior by presenting an in-silico study on a large patient-specific cranial network. The use of fractional-order models is motivated by recent experimental studies indicating that such models provide a new flexible alternative to fitting biological tissue data. This is attributed to their inherent ability to control the interplay between elastic energy storage and viscous dissipation by tuning a single parameter, the fractional order α, as well as to account for a continuous viscoelastic relaxation spectrum. We perform simulations using four viscoelastic parameter data-sets aiming to compare different viscoelastic models and highlight the important role played by the fractional order. Moreover, we carry out a detailed global stochastic sensitivity analysis study to quantify uncertainties of the input parameters that define each wall model. Our results confirm that the effect of fractional models on hemodynamics is primarily controlled by the fractional order, which affects pressure wave propagation by introducing viscoelastic dissipation in the system.Annals of Biomedical Engineering 01/2014; · 3.23 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**We present a systematic comparison of computational hemodynamics in arteries between a one-dimensional (1-D) and a three-dimensional (3-D) formulation with deformable vessel walls. The simulations were performed using a series of idealized compliant arterial models representing the common carotid artery, thoracic aorta, aortic bifurcation, and full aorta from the arch to the iliac bifurcation. The formulations share identical inflow and outflow boundary conditions and have compatible material laws. We also present an iterative algorithm to select the parameters for the outflow boundary conditions by using the 1-D theory to achieve a desired systolic and diastolic pressure at a particular vessel. This 1-D/3-D framework can be used to efficiently determine material and boundary condition parameters for 3-D subject-specific arterial models with deformable vessel walls. Finally, we explore the impact of different anatomical features and hemodynamic conditions on the numerical predictions. The results show good agreement between the two formulations, especially during the diastolic phase of the cycle. © 2013 The Authors. International Journal for Numerical Methods in Biomedical Engineering published by John Wiley & Sons, Ltd.International Journal for Numerical Methods in Biomedical Engineering 01/2014; 30:204-231. · 1.31 Impact Factor

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