Control of Spatio-temporal Chaos in the Heart

Cell Culture Experiments

The mechanism underlying the recruitment of wave emission from heterogeneities in electrical conductance is shown in Fig. 1A. In the presence of an electric field, the membrane potential in the vicinity of a heterogeneity is decreased and increased, i.e. depolarized and hyperpolarized. If the membrane potential is increased above excitation threshold in a region sufficiently large, an excitation wave is created. This mechanism can be studied experimentally in cardiac cell cultures, as shown in Fig.

Control of Spatio-temporal Chaos in the Heart

Spatiotemporally chaotic wave dynamics underlie a variety of debilitating crises in extended excitable systems including the heart. Current strategies for controlling these dynamics employ global, largeamplitude perturbations acting indiscriminately on the system as a whole. For example, the automated external defibrillator commonly found in airports gives via two electrodes a high-energy (1000 V, 30 A, 12 ms) electric shock to terminate the chaotic and ultimately lethal wave dynamics underlying ventricular fibrillation.

Low-energy Control of Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia worldwide affecting an estimated 5.5 million people worldwide. Complications associated with chronic AF include increased risk of both thromboembolism and stroke. Left untreated, paroxysmal AF often progresses to permanent AF, which is resistant to therapy. Although underlying anatomic or pathophysiological factors may fuel its progression, AF itself may lead to its own perpetuation through electric, structural, and metabolic remodeling of atrial tissue.

Unpinning Spiral Waves

While FF-AFP provides remarkable energy reduction compared to conventional therapeutic approaches, the underlying mechanisms remain largely elusive. Further optimization of LEAP requires identifying the mechanisms underlying the interaction of spiral waves and pacing-induced perturbations. One of the constituents of these complex dynamics is the interaction of pinned spirals – spiral waves that are anchored at anatomical obstacles such as fatty tissue, scars or blood vessels – with pulses of an electric field.