Junctional rhythms originate from the AV junction. They occur when the SA node fails or when junctional tissue overrides sinus pacing due to increased automaticity or AV nodal reentry. Rates typically range from 40-60 bpm (junctional escape) but can be faster, accelerated junctional rhythm (60-100bpm) or junctional tachycardia (>100bpm).
Causes
- Sinus node dysfunction
- Increased vagal tone
- Myocardial ischemia or infarction (esp. inferior MI)
- Dig toxicity
- Post-cardiac surgery or ablation
- Myocarditis or infiltrative disease
EKG
- Regular rhythm
- Rate 40–60 bpm (unless accelerated or tachycardic)
- Narrow QRS complexes
- P waves absent, inverted, or after QRS (retrograde conduction)
- Short or absent PR interval if retrograde P waves visible
Significance
- Often benign if compensatory (escape)
- Symptomatic bradycardia can lead to dizziness, syncope, hypotension
- Accelerated junctional rhythm may indicate ischemia or drug effect
- Tachycardia may cause low cardiac output, needs urgent evaluation