Cardiac fibrosis is a well-known arrhythmogenic condition which can lead to sudden cardiac death. Physically,
fibrosis can be viewed as a large number of small obstacles in an excitable medium, which may create
nonlinear wave turbulence or reentry. The relation between the specific texture of fibrosis and the onset of
reentry is of great theoretical and practical importance.
In my talk I present results of several recent studies which show how basic properties of wave propagation
are affected by fibrosis. We also characterize properties of fibrotic texture which led to cardiac arrhythmias
and propose a concept of minimal functional cluster which allows quantitatively predict the arrhythmia
probability for different fibrosis densities and tissue excitabilities.