What irregularity is associated with a premature ventricular contraction (PVC)?

The irregularity associated with a premature ventricular contraction (PVC) is that it is defined as an early contraction of the ventricles. PVCs occur when there is an abnormal electrical impulse in the ventricles that causes them to contract prematurely, disrupting the normal heart rhythm. This early contraction often results in a noticeable heartbeat that can feel like a "skipped" beat.

In contrast, the other options describe characteristics that do not apply to PVCs. P waves occurring before every QRS complex refers to a normal sinus rhythm and does not occur with PVCs, as the impulse is originating early from the ventricles rather than from the atria. Ventricles contracting at a regular rhythm is also inaccurate since PVCs introduce irregularity into the heartbeat. Furthermore, while PVCs may affect heart rate, the idea that it consistently alters the heart rate is misleading, as the heart rate can vary widely depending on numerous factors, and PVCs can occur sporadically without a predictable pattern.