Key result
A time-varying external voltage gradient synchronized and unpinned multiple spiral waves pinned to heterogeneous obstacles in bidomain model simulations.
Why the study?
When multiple pinned spiral waves exist in cardiac fibrillation, their vulnerable unpinning windows generally do not overlap, making them difficult to eliminate simultaneously.
A novel computational strategy using time-varying external voltage gradients can synchronize and unpin multiple spiral waves in cardiac fibrillation models, offering a proof-of-concept for improved defibrillation techniques.
Simulation results support multi-wave unpinning via time-varying gradients; leaves open translation to clinical defibrillation.
Cardiac fibrillation is caused by self-sustaining spiral waves that occur in the myocardium, some of which can be pinned to anatomical obstacles, making them more difficult to eliminate. A small electrical stimulation is often sufficient to unpin these spirals but only if it is applied during the vulnerable unpinning window. Even if these unpinning windows can be inferred from data, when multiple pinned spirals exist, their unpinning windows will not generally overlap. Using phase-based reduction techniques, we formulate and solve an optimal control problem to yield a time-varying external voltage gradient that can synchronize a collection of spiral waves that are pinned to a collection of heterogeneous obstacles. Upon synchronization, the unpinning windows overlap so that they can be simultaneously unpinned by applying an external voltage gradient pulse at an appropriate moment. Numerical validation is presented in bidomain model simulations. Results represent a proof-of-concept illustration of the proposed unpinning strategy which explicitly incorporates heterogeneity in the problem formulation and requires no real-time feedback about the system state.
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Das et al. (2022) studied Cardiac fibrillation. Time-varying external voltage gradient was evaluated on Synchronization and unpinning of spiral waves. A time-varying external voltage gradient synchronized and unpinned multiple spiral waves pinned to heterogeneous obstacles in bidomain model simulations.
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