Monarch Disease Ontology entry MONDO_0000190 (ventricular fibrillation) is a disorder characterized by an electrocardiographic finding of a rapid grossly irregular ventricular rhythm with marked variability in QRS cycle length, morphology, and amplitude. The rate is typically greater than 300 bpm. (CDISC). Also known as: VF, VFib, fibrillation, ventricular, ventricular fibrillation (disease).