What leads to the development of premature ventricular contractions (PVCs)?

Premature ventricular contractions (PVCs) are characterized by early depolarization of the ventricles, often arising from an increased level of irritability in the myocardial tissue. This heightened irritability can be triggered by various factors such as electrolyte imbalances, stress, structural heart changes, or the presence of certain stimulants like caffeine.

When myocardial irritability increases, the heart's cells become more excitable, which can lead to arrhythmias such as PVCs. The early and abnormal contractions occur when these irritable areas in the ventricular myocardium fire before the normal electrical impulses can trigger a contraction, causing the sensation of skipped heartbeats or palpitations.

Understanding this concept highlights the association between electrical stability and the likelihood of PVCs, indicating that increased irritability in the heart's tissues fosters the conditions necessary for these contractions to happen. Therefore, the choice that identifies increased myocardial irritability as a precursor to PVCs accurately captures the underlying mechanism contributing to their development.