  We demonstrate a universal mechanism for terminating spiral waves in
excitable media using an established topological framework. This mechanism
dictates whether high- or low-energy defibrillation shocks succeed or fail.
Furthermore, this mechanism allows for the design of a single minimal stimulus
capable of defibrillating, at any time, turbulent states driven by multiple
spiral waves. We demonstrate this method in a variety of computational models
of cardiac tissue ranging from simple to detailed human models. The theory
described here shows how this mechanism underlies all successful defibrillation
and can be used to further develop existing and future low-energy
defibrillation strategies.
