Which statement best describes a typical PVC on ECG?

• A. Narrow QRS with preceding P waves
• B. Wide QRS with preceding P waves
• C. Wide QRS without a preceding P wave
• D. Normal rhythm

Answer: (C)

PVCs are premature beats that originate in the ventricles. Because the impulse starts in the ventricular tissue rather than the atria, the depolarization spreads through the ventricles in a slower, abnormal way, producing a wide QRS complex (usually greater than 120 ms). There is typically no preceding P wave because the atria aren’t triggering this beat, so you don’t see a P wave just before the wide complex. This combination—an early beat with a wide, bizarre-looking QRS and no preceding P wave—is what characterizes a typical PVC. After a PVC, a compensatory pause often follows. The other patterns describe normal sinus rhythm or atrial-origin beats, which have different P–QRS relationships and QRS widths.