Figure 3.

Action potential duration alternans at slow rates in persistent atrial fibrillation, disorganizing to complex oscillations just preceding atrial fibrillation. This patient showed substantial action potential duration alternans at 500 ms, (A) cycle length 450 ms (mean action potential duration 120 ms for 10 beats), (B) cycle length 400 ms during intermittent atrioventricular block, with a phase reversal (*), (C) Cycle length 290 ms with multiple phase reversals, and (D) cycle length 260 ms, with complex oscillations then atrial fibrillation. (E) Electrical restitution curve with maximum electrical restitution curve slope. Adapted with permission from Narayan et al.⁷