Representative monophasic action potential recordings obtained upon measuring the effective refractory period.
Panel A shows monophasic action potentials (MAP) recorded from the left ventricular (LV) and the right ventricular (RV) epicardium upon extrasystolic stimulations applied at a basic drive cycle length of 550 ms. The moments of S1 and S2 application are shown by vertical dotted lines. The numbers (ms) shown indicate the effective refractory period (last beat in LV MAP) and the LV-to-RV conduction time (second beat in RV MAP). Panel B illustrates location of the LV and RV MAP recording electrodes (open circles), and the LV stimulating (St) electrode (filled circle).