Experiment-specific models of ventricular electrical activation: construction and application

Approaches for determining cardiac bidomain conductivity values: progress and challenges

Modelling the electrical activity of the heart is an important tool for understanding electrical function in various diseases and conduction disorders. Clearly, for model results to be useful, it is necessary to have accurate inputs for the models, in particular the commonly used bidomain model. However, there are only three sets of four experimentally determined conductivity values for cardiac ventricular tissue and these are inconsistent, were measured around 40 years ago, often produce different results in simulations and do not fully represent the three-dimensional anisotropic nature of cardiac tissue. Despite efforts in the intervening years, difficulties associated with making the measurements and also determining the conductivities from the experimental data have not yet been overcome. In this review, we summarise what is known about the conductivity values, as well as progress to date in meeting the challenges associated with both the mathematical modelling and the experimental techniques. Graphical abstract Epicardial potential distributions, arising from a subendocardial ischaemic region, modelled using conductivity data from the indicated studies.

Shock induced electrical activation in structurally detailed models of pig left-ventricular tissue

Detailed models of sample specific structures in pig left-ventricular tissue have been constructed. These models include epicardial and endocardial surfaces, fiber and sheet orientations, vessels and cleavage planes with significant dimensions. This work shows that it is possible to extract from 3D tissue images reduced dimension descriptions of cleavage planes in the heart wall. These descriptions are used to analyze the response of tissue to electrical shocks of varying strengths. The presence of explicit discontinuities in the heart significantly reduces the time required for transmural activation and provides a basis for understanding successful defibrillation.