In this thesis we present a numerical solver for actively contracting heart muscletissue. It uses the finite element method for the discretization and is entirely basedon free open source software packages made available through the FEniCS project.The solver offers a high-level user interface that enables the user to pose real-lifeproblems from the field of cardiac modelling in no more than 10–20 lines of code.
The solver we present is written as an extension to the FEniCS based moduleCBC.Twist, which is developed for solving general problems in large-strain nonlin-ear elasticity.
The passive material properties of the cardiac tissue are described by a trans-versely isotropic, hyperelastic model. We use two different models for the activestress contribution: one is a simple linear function in time, and the other is a set ofordinary differential equations. During contraction the cardiac muscle undergoeslarge deformations. Its material non-linearities has thus been taken into account.
We present numerical results from simulations on a cube representing a slab ofcardiac tissue, a box-shaped test specimen representing a piece of the myocardialwall and finally on the left ventricle itself. In all cases we have achieved phys-iologically reasonable results, with a maximum fiber strain close to, and above,20%.