Morphometry-Based Impedance Boundary Conditions for Patient-Specific Modeling of Blood Flow in Pulmonary Arteries

Abstract

Patient-specific computational models could aid in planning interventions to relieve pulmonary arterial stenoses common in many forms of congenital heart disease. We describe a new approach to simulate blood flow in subject-specific models of the pulmonary arteries that consists of a numerical model of the proximal pulmonary arteries created from three-dimensional medical imaging data with terminal impedance boundary conditions derived from linear wave propagation theory applied to morphometric models of distal vessels. A tuning method, employing numerical solution methods for nonlinear systems of equations, was developed to modify the distal vasculature to match measured pressure and flow distribution data. One-dimensional blood flow equations were solved with a finite element method in image-based pulmonary arterial models using prescribed inlet flow and morphometry-based impedance at the outlets. Application of these methods in a pilot study of the effect of removal of unilateral pulmonary arterial stenosis induced in a pig showed good agreement with experimental measurements for flow redistribution and main pulmonary arterial pressure. Next, these methods were applied to a patient with repaired tetralogy of Fallot and predicted insignificant hemodynamic improvement with relief of the stenosis. This method of coupling image-based and morphometry-based models could enable increased fidelity in pulmonary hemodynamic simulation.

Memory Encoded Throughout Our Bodies: Molecular and Cellular Basis of Tissue Regeneration

“…Certain wound types, such as chronic ulcers (145,146), are difficult to revascularize, and alternative oxygen delivery techniques via diffusion are a viable temporary solution (147). Because of the complex spatiotemporal dynamics of the vasculature, computer modeling is gaining increasing involvement in planning and assessing vascular replacements and other operations (135,148).…”

Group-wise construction of reduced models for understanding and characterization of pulmonary blood flows from medical images

“…Regurgitation results from the absence of a functioning pulmonary valve that maintains one-way blood flow from the right ventricle to the pulmonary artery. Previous ToF blood flow simulations have investigated regurgitation with lumped (Kilner et al, 2009) or idealized (geometry and boundary conditions) three-dimensional (Chern et al, 2008) models, as well as pressure losses for two repair options with either a one-dimensional (Spilker et al, 2007) or a steady three-dimensional (Chai et al, 2010) patient-specific model. In this paper, we combined realistic models of form (three-dimensional geometries) and function (physiological inflow and outlet boundary conditions) as in (Das et al, 2011).…”

Simulation of the human intracranial arterial tree

“…The importance of outflow boundary conditions has been long recognized by the community and the large literature reflects the same (Olufsen 1999;Sherwin et al 2003b;Smith et al 2004;Formaggia et al 2006;Vignon-Clementel et al 2006;Spilker et al 2007). There are several methods to impose the pressure boundary conditions, and the four main approaches are: (i) constant pressure boundary condition, (ii) resistance boundary condition (Sherwin et al 2003b;Formaggia et al 2006;Vignon-Clementel et al 2006), (iii) windkessel model boundary condition (Gibbons & Shadwick 1991;Nichols et al 1998;Formaggia et al 2006), and (iv) impedance boundary condition ( Vignon-Clementel et al 2006;Spilker et al 2007;Steele et al 2007). The resistance, windkessel and impedance boundary conditions are derived from modelling the peripheral resistance and compliance, and require knowledge of the peripheral arterial network characteristics.…”