A New, Low-Energy Defibrillation Strategy: Use of Multiple Electric Field Directions to Reshape Scroll Wave Filaments

Abstract

There is continued interest in developing new, lowenergy methods for cardiac defibrillation. In this computational study, we consider the problem from a new perspective that, in contrast to several previous studies, leads to a strategy that works even when an arbitrarily large number of the rotating action potential waves are present during fibrillation, and works without requiring knowledge of the phases of these rotating waves. We show that sequences of one or more low-energy, electric field pulses, when designed with this strategy in mind, can convert the axes around which the waves rotate from a persistent form into forms that tend to shrink and disappear. When these sequences were applied with field strengths between 1.5 and 2.5 V/cm, 1 to 4 rotating waves representing fibrillation were terminated with success rates (76%-90%) much higher than those obtained using conventional stimuli (14%). Limitations of this study include our use of a simplified model of cardiac geometry and our operation of the simulation in a positive filament tension regime that is also stable to electrical alternans. Nevertheless, we believe that the use of a sequence of electric fields designed to convert all persistent filament shapes to self-extinguishing ones is a promising idea that is worth further examination.

Characterization and Control of Wave Propagation in the Heart

“…Thus, the relative distance to the closest wave emitting site may be larger. Also, Niels Otani and colleagues [114] suggested wave emission from the wall in an orthogonal direction to the direction of wave propagation as a mechanism for removing spirals from the heart and thus to defibrillate. A similar pattern as suggested by them may be an additional reason for the differences in the shock effect.…”