What is a typical P wave behavior in junctional rhythm?

• A. P waves before QRS with normal morphology
• B. P waves after QRS with inverted P waves or absent
• C. P waves not related to QRS
• D. P waves after QRS with normal morphology

Answer: (B)

In junctional rhythm, the pacemaker sits at the AV junction, so the ventricular activation can occur before the atrial activation. This means atrial depolarization often happens after the QRS or may be hidden in it. When P waves are visible, they tend to occur after the QRS and are typically inverted due to retrograde atrial activation. That’s why P waves after the QRS with inverted P waves or absent P waves is the typical pattern.

The other patterns would imply rhythms originating above the AV node (P waves before QRS with normal morphology) or atrial arrhythmias where P waves are not tied to the QRS in the expected way (P waves not related to QRS), which is not characteristic of junctional rhythm.