Normally, the pacemaker of the heart that is responsible for triggering each heart beat (ventricular contraction) is the SA (Sino Atrial) node. However, if the ventricle does not receive triggering signals at a rate high enough, the ventricular myocardium itself becomes the pacemaker (escape rhythm). This is called Idioventricular Rhythm. The rate is usually 20-40 bpm. If the rate is >40 bpm, it is called accelerated idioventricular rhythm

Accelerated idioventricular rhythm

In accelerated idioventricular rhythm, the rate of cardiac contraction is determined by the intrinsic rate of depolarisation of the cardiac cells.It can be present at birth.-Pathophysiology:...

. The rate of 20-40 is the "intrinsic automaticity" of the ventricular myocardium. This is the "backup plan" or "redundancy" built into the body!