  Turbulence of scroll waves is a sort of spatio-temporal chaos that exists in
three-dimensional excitable media. Cardiac tissue and the Belousov-Zhabotinsky
reaction are examples of such media. In cardiac tissue, chaotic behaviour is
believed to underlie fibrillation which, without intervention, precedes cardiac
death. In this study we investigate suppression of the turbulence using
stimulation of two different types, "modulation of excitability" and "extra
transmembrane current". With cardiac defibrillation in mind, we used a single
pulse as well as repetitive extra current with both constant and feedback
controlled frequency. We show that turbulence can be terminated using either a
resonant modulation of excitability or a resonant extra current. The turbulence
is terminated with much higher probability using a resonant frequency
perturbation than a non-resonant one. Suppression of the turbulence using a
resonant frequency is up to fifty times faster than using a non-resonant
frequency, in both the modulation of excitability and the extra current modes.
We also demonstrate that resonant perturbation requires strength one order of
magnitude lower than that of a single pulse, which is currently used in
clinical practice to terminate cardiac fibrillation. Our results provide a
robust method of controlling complex chaotic spatio-temporal processes.
Resonant drift of spiral waves has been studied extensively in two dimensions,
however, these results show for the first time that it also works in three
dimensions, despite the complex nature of the scroll wave turbulence.
