Ultra-low-energy defibrillation through adjoint optimization

TL;DR

This paper demonstrates that adjoint optimization enables ultra-low-energy defibrillation in a cardiac tissue model, significantly reducing energy requirements by exploiting tissue dynamics during vulnerable windows.

Contribution

It introduces a novel adjoint optimization approach to minimize defibrillation energy, achieving three orders of magnitude reduction compared to existing methods.

Findings

Single biphasic pulse can be more effective than LEAP.

Adjoint optimization reduces defibrillation energy by 1000x.

Exploiting vulnerable window dynamics promotes phase singularity annihilation.

Abstract

This study investigates ultra-low-energy defibrillation protocols using a simple two-dimensional model of cardiac tissue. We find that, rather counter-intuitively, a single, properly timed, biphasic pulse can be more effective in defibrillating the tissue than low energy antitachycardia pacing (LEAP) which employs a sequence of such pulses, succeeding where the latter approach fails. Furthermore, we show that, with the help of adjoint optimization, it is possible to reduce the energy required for defibrillation even further, making it three orders of magnitude lower than that required by LEAP. Finally, we establish that this dramatic reduction is achieved through exploiting the sensitivity of the dynamics in vulnerable windows to promote annihilation of pairs of nearby phase singularities.