Continuous electrocardigraphic (ECG) strip during an episode of ventricular fibrillation (VF) that progresses to fine VF and then asystole

At the onset of ventricular fibrillation (VF), the QRS complexes are regular, widened, and of tall amplitude, suggesting a more organized ventricular tachyarrhythmia. Over a brief period of time, the rhythm becomes more disorganized with high amplitude fibrillatory waves; this is coarse VF. After a longer period of time, the fibrillatory waves become fine, culminating in asystole.