Which statement best describes a junctional rhythm?

• A. P waves are absent or retrograde; heart rate 40-60 bpm
• B. P waves are upright before each QRS; rate 60-100 bpm
• C. P waves are before QRS and wide, with slow rate
• D. P waves are absent and QRS is wide

Answer: (A)

A junctional rhythm happens when the AV node acts as the heart’s pacemaker. Because the impulse starts in the AV junction, atrial activation can be delayed or occur after the ventricular activation, so P waves may be absent or appear retrograde (inverted) and may be hidden in or just after the QRS complex. The intrinsic rate from the AV node is slower than the SA node, typically 40–60 beats per minute, which gives a rhythm at that slower rate with a usually normal (narrow) QRS. So the description that best fits is P waves that are absent or retrograde, with a rate around 40–60 bpm. If P waves were upright before each QRS with a normal rate, that would be sinus rhythm. If P waves preceded QRS with a wide QRS and slow rate, or if P waves were absent with a wide QRS, those patterns point to other origins (atrial or ventricular) rather than a junctional rhythm.