The safety factor approach in the analysis of reentrant patterns of activation in the ischemic virtual heart

Traditionally, VF has been directly related to dispersion of refractoriness. However, further theoretical studies relating refractoriness and reentry generation would be helpful to understand their implication. Recently, the safety factor for conduction (SF) has been proposed as a useful parameter to analyze propagation of action potential (AP) and conduction block. In this work, the relative role of refractoriness and the source-sink relationship in conduction block leading to reentry during regional ischemia has been analyzed. Our results show that a) premature stimuli applied at CIs comprised between 170 ms and 204 ms lead to reentry, b) the distribution of SF during reentry is very similar for all the conducted simulations and c) in one third of the re-entries the premature stimulus was blocked at sites where the excitability of the cells was completely recovered.