Key result
Finer spatial segmentation restricts action potential and conduction velocity errors to under ~1% in simulations.
Why the study?
Spatial segmentation is essential for the numerical simulation of excitation propagation in cardiac muscle, motivating an evaluation of its effects on action potential and propagation velocity.
In numerical simulations of cardiac excitation, the space constant of a fully activated membrane is a superior criterion for selecting spatial segmentation compared to the resting membrane space constant.
Answers are grounded in this paper and cite their sources.
Optimizes spatial discretization in cardiac models; extends simulation methodology but leaves open experimental validation before broader use.
Spatial Segmentation in the Simulation of Propagation. Introduction: Spatial segmentation is essential for the numerical simulation of excitation propagation in cardiac muscle. Methods and Results: This study evaluated the effects of spatial segmentation on action potential and on the velocity of propagation in a continuous one‐dimensional model of cardiac muscle [intracellular and extracellular resistivities along (L) and transverse (T) to the muscle fibers: 402 ωcm (Ri, L), 3,620 ωcm (Ri, T), 48 ωcm (Re, L), and 126 ωcm (Re, T), J of Physiol 255:335‐346, 1976) and either Luo‐Rudy (L‐R, Circ Res 68:1501‐1526, 1991) or Beeler‐Reuter (B‐R, J Physiol 268:177‐210, 1977) ionic currents. Related cable equations for active membrane are derived. Spatial segmentations of < 31.2 μm (L, L‐R), < 11.5 μm (T, L‐R), < 44.7 μm (L, B‐R), and < 16.5 μm (T, B‐R) were required for < 1% errors in the characteristic parameters of action potential. Similarly, spatial segmentations of < 54.5 μm (L, L‐R), < 20.1 μm (T, L‐R), < 84.3 μm (L, B‐R), and < 31.2 μm (T, B‐R) were required for < 1% errors in the velocity of conduction. Conclusion: In general, spatial segmentations of < 26.9% and < 50.8% of the space constant of a fully activated membrane gave < 1.0% errors in the characteristic parameters of action potential and in the velocity of propagation, respectively, for both membranes. The action potential duration was relatively insensitive to the spatial segmentation. Our analysis suggests that λfull is a better criterion for the selection of spatial segmentation in numerical simulation than the space constant of the resting membrane.
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Wu et al. (1999) studied Excitation propagation in cardiac muscle. Spatial segmentation in a continuous 1D cardiac muscle model vs. Luo-Rudy vs Beeler-Reuter ionic current models was evaluated on Errors (<1%) in characteristic parameters of action potential and velocity of propagation. Spatial segmentations <26.9% and <50.8% of the fully activated membrane space constant yielded <1.0% errors in action potential parameters and propagation velocity, respectively.
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