Diagnosis of Heart Disease – Circulatory System – Merck …

Ventricular tachycardia must be distinguished from ventricular escape rhythm, as seen with third-degree AV block, and from idioventricular rhythm, a terminal ventricular escape rhythm. A ventricular escape rhythm is a slow rhythm (20–40 bpm) that occurs because higher pacemakers (SA and AV nodes) have failed.

https://www.merckvetmanual.com/circulatory-system/heart-disease-and-heart-failure/diagnosis-of-heart-disease