Bidomain Modeling of Propagation in Cardiac Tissue
G. Plank*
Oxford University Computing Laboratory, Oxford, United Kingdom
A mechanistic understanding of the biophysical processes associated with electrical stimulation of the heart is important for optimizing cardiac bioelectric therapies such as electrical pacing or defibrillation. The bidomain model which explicitly accounts for current flow in the interstitial/ extracellular domain plays an instrumental role in investigating how extracellulary applied fields are transduced into changes in transmembrane voltage, Vm. Although numerous hypotheses were put forward to explain the field-tissue interaction, none of them provided a unifying theoretical link to explain various experimental observations. Eventually, it was the bidomain model which provided the desperately sought after ”missing link”. Recasting the bidomain equations revealed that a term, referred to as activating function, is the driving force behind field-induced polarization patterns in the heart. Theoretical studies based on bidomain theory predicted that field-induced tissue response patterns are far more complex than previously believed. Irrevocable experimental confirmation of the theoretical findings followed only a few years later.
For many years, numerical simulations relying upon bidomain theory were subjected to severe limiations which prevented anatomically and functionally detailed simulations at the organ level due to the enormous computational expense. Today, using high performance supercomputers and building on the significant progress made within the theoretical community, bidomain simulations of the heart can be conducted at an almost microscopic level of detail using the most recent descriptions of the cellular dynamics. Using such highly detailed individualized ”in-silico” models of the heart allow to perform ”virtual experiments” that can be matched and validated against real wet-lab experiments or available clinical data. The talk will focus on micro-anatomically detailed bidomain simulations of the heart for investigating mechanisms underlying arrhythmogenesis and defibrillation at the organ level.