Which rhythm is an accelerated junctional rhythm, indicating an irritable junction overriding the normal pacemaker and typically associated with AMI, open‑heart surgery, myocarditis, or digoxin toxicity?

• A. Junctional Tachycardia
• B. Accelerated Junctional Rhythm
• C. First Degree Heart Block
• D. Atrial Tachycardia

Answer: (B)

Accelerated junctional rhythm occurs when the AV junction becomes the dominant pacemaker and fires more rapidly than the SA node, but not fast enough to be called tachycardia. The impulse travels to the ventricles through a narrow QRS, and atrial activity may be hidden or appear retrogradely (P waves after or inverted with respect to the QRS). The typical rate is about 60–100 beats per minute. This pattern fits the described scenario because it reflects a irritable junction overriding the normal pacemaker, and it is classically seen in settings like myocardial infarction, recent open‑heart surgery, myocarditis, or digoxin toxicity. It’s distinct from junctional tachycardia (which is faster than 100 bpm), first‑degree heart block (characterized by a prolonged PR interval with a normal rate), and atrial tachycardia (originates in the atria with different P‑wave morphology and usually a higher rate).