junctional rhythm
Cardiac rhythm originating from the AV junction with narrow QRS complexes and absent or inverted P waves.
Full Definition
Junctional rhythm is a cardiac rhythm that originates from the atrioventricular (AV) junction, specifically the AV node or bundle of His, when the sinoatrial node fails to function as the primary pacemaker. The rhythm is characterized by narrow QRS complexes (unless aberrant conduction is present), absent P waves, or P waves that appear inverted in leads II, III, and aVF due to retrograde atrial activation. Junctional rhythms typically occur at rates of 40-60 beats per minute and may be seen in conditions such as digitalis toxicity, inferior myocardial infarction, or sick sinus syndrome. While generally well-tolerated, the loss of atrial contribution to ventricular filling can reduce cardiac output.
Usage
Usage note: Distinguish from junctional tachycardia by rate; note P wave morphology and timing.
In Context
- "The patient developed junctional rhythm at 45 bpm following inferior wall myocardial infarction with first-degree AV block." — Coronary care unit note
- "Junctional rhythm with retrograde P waves was observed during episodes of sinus node dysfunction." — Holter monitor interpretation