Fig. 6. Initiation of a sustained reentrant ventricular tachycardia after a 100-mJ contusion with two premature paced extrasystoles in frozen left ventricular epicardium. Three consecutive activation maps are given and show the spread of depolarization. Numbers indicate local activation times in milliseconds. Isochrones are drawn at 10-ms intervals. The thick isochrones indicate local conduction blocks. Arrows indicate direction of activation. Double bars indicate the stop of propagation in the direction considered. The closed circle represents the pacing site. The hatched area corresponds to the impact contusion zone with no electrical activity. (A ) Shows activation of epicardium after the last stimulus (S1) after contusion (T0). (B ) Depicts the activation of the epicardium after contusion (T0) during the last premature pacing (S3). The first beat of the sustained ventricular tachycardia (first VTB) is shown in C . All maps present the same frontal view of the heart. (D ) Consists of seven different electrograms recorded from surrounding electrodes in the right upper panel. FW = ventricular free wall; LAD = left anterior descending coronary artery. (See text for further descriptions.)