Which statement about junctional P waves is correct?

• A. P waves are upright before QRS
• B. P waves are inverted before QRS
• C. P waves may be inverted or missing
• D. P waves are absent

Answer: (C)

When the heartbeat originates near the AV node (the junction), atrial depolarization often travels retrograde toward the atria. That changes how the P wave appears on the ECG. Because the impulse is coming from the junction rather than the atria, the P waves can be inverted relative to the baseline, or they may be hidden in or right after the QRS complex and thus not clearly visible.

So the best statement is that P waves may be inverted or missing. This reflects the variable visibility and polarity of atrial activity when the impulse starts at the AV junction.