Quasi-static image-based immersed boundary-finite element model of left ventricle under diastolic loading.

Hao Gao,Xiaoyu Luo,Boyce E Griffith,Colin Berry,Huiming Wang

doi:10.1002/cnm.2652

Abstract

Finite stress and strain analyses of the heart provide insight into the biomechanics of myocardial function and dysfunction. Herein, we describe progress toward dynamic patient-specific models of the left ventricle using an immersed boundary (IB) method with a finite element (FE) structural mechanics model. We use a structure-based hyperelastic strain-energy function to describe the passive mechanics of the ventricular myocardium, a realistic anatomical geometry reconstructed from clinical magnetic resonance images of a healthy human heart, and a rule-based fiber architecture. Numerical predictions of this IB/FE model are compared with results obtained by a commercial FE solver. We demonstrate that the IB/FE model yields results that are in good agreement with those of the conventional FE model under diastolic loading conditions, and the predictions of the LV model using either numerical method are shown to be consistent with previous computational and experimental data. These results are among the first to analyze the stress and strain predictions of IB models of ventricular mechanics, and they serve both to verify the IB/FE simulation framework and to validate the IB/FE model. Moreover, this work represents an important step toward using such models for fully dynamic fluid–structure interaction simulations of the heart. © 2014 The Authors. International Journal for Numerical Methods in Engineering published by John Wiley & Sons, Ltd.

Highlights

Cardiac diseases have been a major public health burden in industrialized countries for more than a century and are the leading causes of morbidity and mortality worldwide
Using this model along with a nonlinear finite element (FE) method for the structural mechanics, we studied the effects of changes in fiber organization and material properties on diastolic mechanics, and we demonstrated that changes to the fiber orientations have substantially larger effects on the passive response of the myocardium than changes to the sheet orientations [15]
We apply one of these schemes, a hybrid finite difference-finite element immersed boundary (IB) method [38] to simulate left ventricular biomechanics under diastolic loading conditions, and we present an initial verification of the accuracy of the predicted stress and strain distributions by comparing the model results to those generated by a well-established FE solver

Summary

Introduction

Cardiac diseases have been a major public health burden in industrialized countries for more than a century and are the leading causes of morbidity and mortality worldwide. The biomechanics of heart disease and heart failure remain incompletely understood. It is well known that alterations in myocardial stress and strain distributions can have a significant impact on maladaptive processes such as hypertrophy [1, 2], but it is not possible to measure directly intramural stress distributions in patients. Three-dimensional stress and strain distributions are readily provided by computational models of the heart, and such models could assist H. In patient risk stratification and inform clinical decision making [3]. An improved understanding of ventricular biomechanics is important for optimizing medical therapies and surgical procedures aimed at restoring normal heart function [4]

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