Rotational activity: serial images and acceleration during the initial seconds of ventricular fibrillation. (A) Patient with dilated cardiomyopathy and rotational activity in the right ventricle (total 12 rotations, the driver area in this patient, is shown in Figure 4B). Rotational activity is shown as full phase progression around a centre-point in colour-coded phases of wave propagation. The series of images show two full rotations (cycle length 150 ms) in colour-coded activation maps around a pivot point (asterisk in first and last image). (B) In another patient with dilated cardiomyopathy, rotational activities occurred in lateral left ventricle at the beginning of ventricular fibrillation (1–1.9 s) and one second later (3.1–4.3 s), in addition to other activities (not shown). The top trace shows a sample unipolar electrogram. Rotational activity is shown as full phase progression around a center-point in colour-coded phases of wave propagation. Coloured points indicate the sites where unipolar electrograms are recorded around the pivot point and show sequential activation (timing shown by red points). The mean local cycle length is 191 ms during the 1–1.9 s ventricular fibrillation interval and has decreased to 172 ms during the 3.1–4.3 s ventricular fibrillation interval.