• Enhanced automaticity in the AV junction produces PJCs.

Rate: Depends on rate of underlying rhythm

Rhythm: Irregular whenever a PJC occurs

P Waves: Absent, inverted, buried, or retrograde in the PJC

PR Interval: None, short, or retrograde

QRS: Normal (0.06–0.10 sec)

Clinical Tip: Before deciding whether isolated PJCs are insignificant, consider the cause.