Which rhythm is junctional tachycardia, which can be caused by anoxia, ischemia, AV node malfunction, edema after open‑heart surgery, or digoxin toxicity and can lead to more serious AV block?

• A. Atrial Fibrillation
• B. Junctional Tachycardia
• C. Atrial Flutter
• D. Premature Atrial Complex

Answer: (B)

Junctional tachycardia is a fast rhythm that originates from the AV junction near the AV node. It typically produces a narrow QRS complex because ventricular conduction is normal, but the atrial activity may be hidden or inverted due to retrograde atrial activation. The rate is usually in the range of about 100–180 beats per minute and the rhythm tends to be regular. This rhythm is classically linked to conditions that irritate or damage the AV node, such as anoxia or ischemia, edema around the AV junction after open‑heart surgery, AV nodal dysfunction, or digoxin toxicity. Because the AV node is driving the ventricle at a high rate, there is a potential for progression to more serious AV conduction abnormalities if the nodal tissue becomes overwhelmed.

This fits the described scenario because the etiologies listed—anoxia, ischemia, AV node malfunction, edema after surgery, and digoxin toxicity—are well-known triggers for AV nodal–derived tachycardia. In contrast, atrial fibrillation shows irregularly irregular rhythm with no distinct P waves, atrial flutter has characteristic sawtooth atrial activity, and a premature atrial complex is a single early beat, not a sustained tachycardia.