Originate from an irritable focus in the ventricles. Occur early, before the next expected beat in the rhythm.
QRS is equal to or greater than (≥) 0.12 second
Unifocal/UniformPVCs
Same shape in the same lead & originate from the same site (focus)
Multifocal/MultiformPVCs
Different shapes in the same lead & usually originate from different sites (foci)
Pairs or Couplets
2 sequential PVCs (in row)
Runs(bursts or salvos)
3 or more sequential PVCs are called “ventricular tachycardia” (VT)
Bigeminy
normal beats & premature beats occur alternately in repeating pattern
R-on-T PVCs
When R wave of PVC falls on T wave of preceding beat (Vulnerable period)
Ventricular Escape Beat
Wide, bizarre ventricular beat that occurs after a pause in rhythm if supraventricular pacemakers fail to initiate an impulse.
Appears late, after the next expected beat in underlying rhythm.
Idioventricular Rhythm (IVR)
Three or more sequential ventricular escape beats occurring at a rate of 20 to 40 beats/min.
Accelerated Idioventricular Rhythm (AIVR)
Rate of 40 - 100 bpm
Ventricular Tachycardia (VT)
•VT exists when 3 or more PVCs occur in a row at >100 bpm.
Non-sustained VT: lasts < 30 seconds
Sustained VT: lasts > 30 seconds
Ventricular Fibrillation (VF)
Originates in the ventricles. No organized depolarization of the ventricles, so ventricular muscle quivers, & no effective contraction, no CO & no pulse.
Asystole (Flat Line, Cardiac Standstill)
Asystole is a total absence of ventricular electrical activity. No HR or rhythm, no pulse, & no CO.