Disorder in CRU positions accelerates synchronization of CRU firing and AP ignition process. (A and B) Shown are representative cycles of AP firing (V_m, blue curves) for 500 ms simulation time beginning from the MDP (time = 0) for two CRU distributions: uniformly random (A) and square lattice (B). The ignition process in both cases is characterized by simultaneous activation of CRUs firing (black), I_NCX (red), and I_CaL (green, truncated) during diastolic depolarization. However, the activation kinetics is faster in the uniformly random case so its diastolic depolarization is about twice shorter.