• Also called ectopic or extrasystole

Rate:                Underlying rate 85/min, plus one PVC

Rhythm:           Irregular because of PVC

P wave:            Present before normal QRS, absent before PVC

PR interval:      Normal before normal QRS complexes, unmeasurable before PVC

QRS complex:  Normal QRS complexes, one abnormal broad QRS (the PVC)

• in this case, contractile myocardium is spontaneously producing action potentials
• This QRS complex is shaped differently from a normal QRS complex because it originates in the ventricles and does therefore not follow the usual pattern of conduction from the SA node to AV node to bundle of His
• The place of origin is called an 'ectopic' pacemaker in the ventricle (can also occur in atria).
• It is usually followed by a brief compensatory pause, until the next sinus node impulse occurs.

Most PVCs do not require clinical intervention