Computer simulations and nonlinear dynamics have provided invaluable tools for illuminating the underlying mechanisms of cardiac arrhythmias. Here, we review how this approach has led to major insights into the mechanisms of spatially discordant alter . . .

Cardiac myocytes are excitable cells in which an external current stimulus depolarizes the membrane potential to elicit an action potential. This action potential then triggers calcium release from intracellular stores, which mediates contraction. Con . . .

When a cardiac cell is rapidly paced it can exhibit a beat-to-beat alternation in the action potential duration (APD) and the intracellular calcium transient. This dynamical instability at the cellular level has been shown to correlate with the genesi . . .

Spatially discordant alternans in membrane voltage (Vm) and intracellular calcium (Cai) is linked to fatal arrhythmias. Two mechanisms for the genesis of discordant alternans have been proposed, i.e., dynamical instability due to conduction velocity ( . . .

Spatially discordant alternans, where the action potential duration (APD) and the calcium (Ca) transient can alternate with opposite phase in different regions of tissue, can lead to large spatial gradients of refractoriness which can promote wave bre . . .

The L-type Ca current (ICa,L), essential for normal cardiac function, also regulates dynamic action potential (AP) properties that promote ventricular fibrillation. Blocking ICa,L can prevent ventricular fibrillation, but only at levels suppressing co . . .

When cardiac tissue is rapidly paced, spatially discordant APD alternans can emerge, i.e. regions of long-short APD alternation adjacent to regions with short-long APD alternation. This phenomeon is potentially arrhythmogenic since it leads to the for . . .

Alternans, a condition in which there is a beat-to-beat alternation in the electromechanical response of a periodically stimulated cardiac cell, has been linked to the genesis of life-threatening ventricular arrhythmias. Optical mapping of membrane vo . . .

Mathematical modeling of the cardiac action potential has proven to be a powerful tool for illuminating various aspects of cardiac function, including cardiac arrhythmias. However, no currently available detailed action potential model accurately repr . . .

In homogenous tissue, conduction velocity restitution (CVR) is required for the development of spatially discordant alternans (SDA) except after an ectopic beat. We hypothesized that global capture of monolayers would eliminate CV gradients and SDA wo . . .