What are premature ventricular contractions?

• A. Abnormal action potentials within the AV node or ventricles, often due to stress or stimulants.
• B. Early atrial impulses causing extra P waves.
• C. Ventricular tachycardia.
• D. Supraventricular premature beats.

Answer: (A)

Premature ventricular contractions are extras beats that start in the ventricles, not in the atria, and occur earlier than the next expected normal beat. They arise from an ectopic ventricular focus, so the impulse spreads through the ventricles abnormally, producing a wide, bizarre QRS complex and usually without a preceding P wave. Because the ventricle fires early and outside the normal conduction pathway, you often see a compensatory pause after the beat. They’re commonly triggered by factors like stress or stimulants. This description—the abnormal ventricular origin and the resulting premature, wide QRS beat—is why this option best captures what PVCs are.