Junctional escape rhythm typically originates from which location?

• A. Ventricular Purkinje system
• B. AV node (junctional) with absent or inverted P waves
• C. Atrial tissue
• D. SA node

Answer: (B)

Junctional escape rhythm arises when the AV node’s area takes over as the pacemaker because the higher pacing from the SA node is not driving the heart. It typically fires at about 40–60 beats per minute. Because the impulse starts in the AV junction and then moves to the ventricles, atrial activation happens retrogradely. That’s why P waves are often absent or inverted and may appear after the QRS or be hidden within it, while the QRS is usually narrow since the ventricles are activated through the normal His-Purkinje pathway.

If the rhythm originated from the ventricular Purkinje system, you’d expect a wide QRS and a slower rate. If it came from atrial tissue, the P waves would precede the QRS. If the SA node were driving, you’d see regular upright P waves before each QRS with normal conduction. The combination of a 40–60 bpm rate and absent or inverted P waves points to AV nodal (junctional) origin.