Rate: 40–60 bpm

Rhythm: Regular

P Waves: Absent, inverted, buried, or retrograde

PR Interval: None, short, or retrograde

QRS: Normal (0.06–0.10 sec)

Clinical Tip: Sinus node disease that causes inappropriate slowing of the sinus node may exacerbate this rhythm. Young, healthy adults, especially those with increased vagal tone during sleep, often have periods of junctional rhythm that are completely benign, not requiring intervention.