Click on image to view larger version.

Figure 2 Phase 2 reentry. Reentrant activity was induced by exposure of a canine ventricular epicardial preparation to simulated ischemia. Microelectrode recordings were obtained from four sites as shown in the schematic (upper right). After 35 min of ischemia, the action potential dome develops normally at site 4, but not at sites 1, 2 or 3. The dome then propagates in a clockwise direction, reexciting sites 3, 2 and 1 with progressive delays, thus generating a reentrant extrasystole with a coupling interval of 156 ms at site 1. basic cycle length = 700 ms. A similar phenomenon is observed upon exposure of right ventricular epicardium to acetylcholine, potassium channel openers and inhibitors of sodium and calcium inward currents. Adapted with permission from Lukas and Antzelevitch (92).