Complex restitution behavior and reentry in a cardiac tissue model for neonatal mice

Figures

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  Figure 1. Sketch of the components of the Wang–Sobie model. The model distinguishes 14 sarcolemmal currents and describes intracellular calcium cycling between different model compartments (myoplasm, subspace, junctional sarcoplasmic reticulum [JSR], network sarcoplasmic reticulum [NSR]). The calcium concentrations are buffered by troponin, calmodulin, and calsequestrin [CSQN].

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  Figure 2. Effects of long‐term pacing: The original model drift upon pacing at 1 Hz is eliminated by conservative stimulation and removal of I Cl,Ca. The time course of the intracellular potassium concentration (solid lines) and of an aggregate measure of drift ∆tot (dotted lines) is shown.

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  Figure 3. (A) Action potential (AP) in a single cell and in tissue. Time t = 0 ms was defined as the time point, when the upstroke surpasses −60 mV to align the two APs. (B) Time course of the stimulus current (single cell) and the electrotonic current (tissue). The upper inset shows a magnified view of the fast dynamics at the start of the action potential (AP), whereas the lower inset shows the small amplitude electrotonic currents during repolarization.

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  Figure 4. (A) action potential duration (APD) as a function of basic cycle length (BCL). Three examples of S1–S2 restitution curves (fixed S1, varying S2) and the dynamic restitution curve (S1 = S2) is shown. (B) Diastolic sodium and calcium concentration at steady state as a function of the pacing frequency. (C,D) Membrane potential and intracellular calcium concentration, respectively, during different steady‐state action potentials (APs).

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  Figure 5. Restitution in a cable. Properties of action potential (AP) #45 and 46 after start of stimulation are shown for each basic cycle length (BCL). (A) Action potential duration (APD) measured at a cell 1 cm from the left of the cable. (B) CV measured between 1 and 2 cm from the left of the cable. (C) Spatial variations in APD at BCL = 130 ms. (D) Spatial variations in APD at BCL = 140 ms.

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  Figure 6. Spiral wave dynamics. (A) Snapshots of the membrane potential at time t/s ∈ {0.25, 1.0, 2.5, 5.0} (from left to right). (B) Histogram of the periods of the electrical activity during t/s ∈ [1.0, 2.0]. (bin size 1 ms). (C) Meandering of the spiral core for t/s ∈ [1.0, 2.5]. (D) Meandering of the spiral core for t/s ∈ [3.5, 5.0].