Which term describes a premature atrial impulse causing an early heartbeat?

• A. PVC Premature Ventricular Contractions
• B. Purkinje Fibers
• C. PAC Premature Atrial Contractions
• D. QRS Complex

Answer: (C)

Premature atrial contractions occur when an atrial focus fires early, producing a beat sooner than expected. On an ECG you’ll see an early P wave with a distinct shape, sometimes riding on the preceding T wave, followed by a normal QRS complex because the ventricles usually respond normally to the premature atrial impulse. This distinguishes it from a premature ventricular contraction, which comes from the ventricles and typically creates a wide, abnormal QRS without a preceding P wave. The Purkinje fibers are part of the ventricular conduction system, not a term for a premature beat, and the QRS complex is the ventricular depolarization phase, not the description of an early beat itself. So the term describing a premature atrial impulse causing an early heartbeat is Premature Atrial Contraction.