(A) Heat maps show how the cycle lengths of graft-induced ectopic beats in a host ventricular CM (left) and spontaneously beating graft PSC-CMs (right) change with gap junctional resistance (Rgap) and cleft width for 1:4 host-graft coupling configuration; PSC-CMs had a range of Id (3.1, 3.3, 3.5, and 3.7 μA/μF) with initial states randomized. (B-E) Representative Vm traces of host and graft CMs (left) and junctional gating (right). A wide range of activation patterns were observed from (B) 1:1 capture and instances of (C) 3:1, (D) 5:1, and (E) 11:1 block. Across all traces, junction 4 exhibited the largest gating fluctuations.