In silico optical control of pinned electrical vortices in an excitable biological medium

Abstract

Vortices of excitation are generic to any complex excitable system. In the heart, they occur as rotors, spirals (2D) and scroll waves (3D) of electrical activity that are associated with rhythm disorders, known as arrhythmias. Lethal cardiac arrhythmias often result in sudden death, which is one of the leading causes of mortality in the industrialized world. Irrespective of the nature of the excitable medium, the rotation of a rotor is driven by its dynamics at the (vortex) core. In a recent study, Majumder et al (2018 eLife 7 e41076) demonstrated, using in silico and in vitro cardiac optogenetics, that light-guided manipulation of the core of free rotors can be used to establish real-time spatiotemporal control over the position, number and rotation of these rotors in cardiac tissue. Strategic application of this method, called 'Attract-Anchor-Drag' (AAD) can also be used to eliminate free rotors from the heart and stop cardiac arrhythmias. However, rotors in excitable systems, can pin (anchor) around local heterogeneities as well, thereby limiting their dynamics and possibility for spatial control. Here, we expand our results and numerically demonstrate, that AAD method can also detach anchored vortices from inhomogeneities and subsequently control their dynamics in excitable systems. Thus, overall we demonstrate that AAD control is one of the first universal methods that can be applied to both free and pinned vortices, to ensure their spatial control and removal from the heart and, possibly, other excitable systems.

Mechanism of Spiral Wave Unpinning in the Belousov–Zhabotinsky Reaction with a DC Electric Field

“…All excitation waves, irrespective of the mechanism of formation and the nature of the substrate medium, have very similar dynamics. The spiral waves can get attracted to heterogeneities in the medium and form very stable rotating patterns around the boundary of these heterogeneities. − Such pinning has been observed in chemical systems and also in physiological tissue, both in the experimental settings and in their mathematical models. − The pinned waves are very stable, and they can only be unpinned by careful external intervention. − This problem has attracted attention recently because such pinned waves are believed to play an essential role in cardiac arrhythmia control …”