Effects of Dantrolene on Arrhythmogenicity in Isolated Regional Ischemia-Reperfusion Rabbit Hearts with or without Pacing-Induced Heart Failure

Figure 5

VF induction and VF conversion to VT during dantrolene administration in a failing heart. (a) tracings corresponding to the points labeled in panel (b) during rapid pacing (PCL = 90 ms) at baseline (left subpanel) and with dantrolene (right subpanel). The red arrows indicate wavefront propagation and the white lines indicate conduction block. (b) Schematic illustration of the mapped region (left subpanel) and isochronal maps (right subpanels) corresponding to two consecutive beats labeled in panel (a) (left subpanel, red bar). (c) Ca_i and APD alternated in synchrony. SDA was not induced at PCL = 140 ms until it was shortened to 120 ms at baseline but was induced at PCL = 140 ms with dantrolene infusion (panel (e), right subpanel). The black arrows indicate nodal lines. (d) and (e) isochronal maps of VF initiation and VF conversion to VT corresponding to the period labeled in panel (a) (right subpanel and red and blue bars, resp.). The white dashed lines indicate functional conduction block; white asterisks indicate focal breakthrough.

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