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It has been postulated that cardiac cell models accounting for changes in intracellular ion concentrations violate a conservation principle, and, as a result, computed parameters (e.g., ion concentrations and transmembrane potential, V(m)) drift in time, never attaining steady state. To address this issue, models have been proposed that invoke the charge(More)
In a sufficiently short reentry pathway, the excitation wave front (head) propagates into tissue that is partially refractory (tail) from the previous action potential (AP). We incorporate a detailed mathematical model of the ventricular myocyte into a one-dimensional closed pathway to investigate the effects of head-tail interaction and ion accumulation on(More)
The detailed processes involved in spiral wave breakup, believed to be one major mechanism by which tachycardia evolves into fibrillation, are still poorly understood. This has rendered difficult the proper design of an efficient and practical control stimulus protocol to eliminate such events. In order to gain new insights into the underlying(More)
A fast algorithm called the modified backward Euler (mBE) method, an explicit, variable timestep method, has been developed. Despite its explicit nature, the algorithm is unconditionally stable, allowing the use of timesteps several orders of magnitude larger than the timestep limit imposed by forward Euler methods. A guard cell algorithm also allows the(More)
Spatial dispersion of refractoriness and discordant action potential duration (APD) alternans, resulting in local conduction block, have been shown to cause wavebreak that can lead to ventricular fibrillation (VF). Previously, we developed a theory, based on action potential restitution functions, that predicts when the requisite conduction block can be(More)
Presently, the nature of action potential propagation deep within myocardial tissue is unclear. As a result, a complete understanding of cardiac dynamics remains elusive. Here we present a technique using ultrasound and electromechanical modeling that has the potential to unlock this mystery. We also present information suggesting tension in the heart(More)
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