Key result
Changes in intracellular conductivity and the degree of intracellular anisotropy critically affect the stability and self-termination of reentrant waves in simulated ischemic cardiac tissue.
Computational modeling demonstrates that intracellular conductivity and anisotropy are critical determinants of whether reentrant arrhythmias maintain or spontaneously terminate in acute ischemia.
Hypothesis-generating for reentry in ischemia; leaves open whether modulating intracellular conductivity alters clinical arrhythmia outcomes.
The relation between reentrant activity and occurrence of cardiac arrhythmias still is a topic of intensive investigation. Reentries are strictly related to and enhanced by the complex structure of cardiac tissue, characterized by multi-sized electrophysiological and spatial heterogeneities. However, the structure and the function of the tissue can sometimes also promote phenomena of spontaneous termination of waves. The role played by the tissue in this scenario is not well understood and yet under investigation. In this study, we implemented a bidomain formulation of the phase I of the Luo and Rudy action potential model in 2D under ischemic conditions. We investigate how the size of ischemic heterogeneities and tissue conduction properties may affect the system dynamics and drive it towards maintenance of reentrant activity or quiescence. The main findings show that: (a) for the stability of the waves, changes of conductivity in the intracellular space are more critical than alterations in the extracellular space; (b) the maintenance or the self-termination of pinned spirals is strongly dependent not only on the size of the heterogeneities but also on the degree of intracellular anisotropy. These findings confirm and extend results obtained from previous investigations. In addition, since experimental values of conductivity tensors reported in the literature are not consistent, an overview of possible scenarios arising from a broader range of assumed anisotropy values is provided in relation to different sizes of ischemic heterogeneities. In this perspective, simulations are shown to compare the impact of different degrees of tissue anisotropy on wave dynamics.
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Boccia et al. (2016) studied Myocardial acute ischemia. Ischemic heterogeneities and tissue conduction properties was evaluated on Maintenance of reentrant activity or quiescence. Changes in intracellular conductivity and the degree of intracellular anisotropy critically affect the stability and self-termination of reentrant waves in simulated ischemic cardiac tissue.
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