Critical role of pinning defects in scroll-wave breakup in active media

TL;DR

This paper uncovers a new mechanism where pinning defects in excitable media can induce scroll wave breakup, leading to chaos, with significant implications for understanding cardiac arrhythmias.

Contribution

It introduces a novel defect-induced pathway for scroll wave breakup involving pinning obstacles, expanding the understanding beyond filament dynamics.

Findings

Pinning defects can cause scroll wave breakup far from the filament.

Breakup leads to spatiotemporal chaos in the medium.

Obstacles may play a critical role in cardiac arrhythmias.

Abstract

The breakup of rotating scroll waves in three-dimensional excitable media has been linked to important biological processes. The known mechanisms for this transition almost exclusively involve the dynamics of the scroll filament, i.e., the line connecting the phase singularities. In this paper, we describe a novel defect-induced route to breakup of a scroll wave pinned by an inexcitable obstacle partially extending through the bulk of the medium. The wave is helically wound around the defect inducing sudden changes in velocity components of the wavefront at the obstacle boundary. This results in breakup far from the filament, eventually giving rise to spatiotemporal chaos. Our results suggest a potentially critical role of pinning obstacles in the onset of life-threatening disturbances of cardiac activity.