In ventricular tachycardia, what is commonly observed about P waves?

• A. Often no clear P waves.
• B. P waves are always visible and precede QRS.
• C. P waves occur after QRS at fixed intervals.
• D. P waves inverted in all leads.

Answer: (A)

In ventricular tachycardia the rhythm is driven by the ventricles, not the atria. This ventricular origin often leads to AV dissociation, where the atrial and ventricular rhythms run independently. Because of this dissociation and the rapid, wide QRS complexes, the atrial signal (P waves) is frequently obscured or does not occur in a clear, fixed relationship to the QRS. As a result, P waves are often not clearly visible on the tracing.

If P waves do appear, they typically do not precede the QRS in a consistent, orderly way, and they may even occur after the QRS at irregular or indeterminate intervals, reflecting the lack of a stable atrioventricular connection during VT. This makes the observation of clearly visible P waves uncommon in VT.

The other statements would suggest a different rhythm mechanism. P waves preceding QRS implies normal AV conduction with a supraventricular origin, which isn’t the defining feature of VT. P waves after QRS at fixed intervals could imply a specific retrograde conduction pattern, not the usual VT pattern. P waves inverted in all leads isn’t a reliable hallmark of VT either.