Premature ventricular contraction (PVC), also known as ventricular premature beat (VPB) or extrasystole, is a form of irregular heartbeat in which the ventricle contracts prematurely. This results in a "skipped beat" followed by a stronger beat. Individuals with the condition may report feeling that his or her heart "stops" after an attack. PVCs are also called heart palpitations (although there are many other forms of arrhythmia). The depolarization begins in the ventricle instead of the usual place, i.e. the sinus node. PVCs can be a useful natural probe, since they induce Heart rate turbulence whose characteristics can be measured, and used to evaluate cardiac function.