(A) A substrate for VT. (B) A substrate for VF. (C) A substrate with diffuse fibrosis. (D) A substrate with an anatomical scar. In each panel, successive frames (from left to right) show the voltage distribution in the monolayers at subsequent relevant time points. The left column shows established reentrant tachyarrhythmias. The middle column shows, for the different arrhythmia conditions, stages of advanced repolarization in the arrhythmia termination process (large dark blue areas), while the right column shows the final tissue-wide repolarization (dark blue) stage, thereby allowing restoration of sinus rhythm (SR). The insets show the corresponding situation in the absence of BioICD channels. (E–H) Voltage time series extracted from representative cardiomyocytes (white asterisks) in the simulation domains of situations A-D, respectively. (I) The BioICD channel has no significant influence on the action potential (AP) at sinus rhythm (1.2 Hz, left AP traces), but slightly increases the AP duration in the tail (APD90) at close-to-arrhythmic frequencies (right AP traces). The dotted line of the widest AP in the right traces shows the AP at 1.2 Hz for reference. The orange lines show the APs without BioICD current (control). (J) APD restitution curve for the original parameters of the human ventricular cardiomyocyte model, with and without BioICD channel. Orange shading is used to indicate the region of the restitution curve where the slope exceeds 1. DI, diastolic interval.