The heart beats about 100 000 times in one day and about 35 million times in a year. It is the primary organ of your circulatory system as it pumps blood throughout your body foreseeing oxygen and nutrients to the tissues. The function of the heart is in part regulated by its intrinsic material behavior, which is described by various interesting features, such as nonlinearity, anisotropy and viscoelasiticy. Mechanical characterization of the myocardium is important to better understand how the material properties contribute to cardiac function, and how these properties are altered in pathological conditions. In vivo mechanical testing is however currently impossible, and therefore we rely on ex vivo mechanical testing that mimics the in vivo conditions as closely as possible. The measured data provides the relation between two physical quantities such as stress and strain, and allows to assess how this relation alters depending on the direction, stretch state and time. Additionally, we can use a constitutive model - a mathematical model describing the relation between stress and strain - to characterize the complex behavior of the myocardium with a few parameters.  

This thesis focuses on optimizing the parameter fitting of the myocardial constitutive model, for which we collaborate with the FIBEr-lab of the KULeuven (prof. Famaey). The FIBEr-lab has ample of experience and expertise in testing various types of tissue (arteries, brain, bone etc), but not myocardial tissue. Hereto, we will analyze biaxial mechanical test data of 14 pig hearts, of which a sample of the left ventricular free wall and interventricular septum is available (see fig. 1). The sample of the interventricular septum is presumably infarcted after balloon occlusion of the left anterior descending coronary artery.