Figure 2. MAP recordings obtained during the incremental pacing protocol.

Typical traces observed at resting (8 Hz; A) and exercising (13.5 Hz, B) heart rates in the WT RV epicardium (a), WT RV endocardium (b), flecainide-treated WT RV epicardium (c), Scn5a+/− RV epicardium (d) and flecainide-treated Scn5a+/− RV epicardium (e). The flecainide-treated Scn5a+/− RV epicardium shows longer latencies at both pacing rates and alternans at the higher rate.