What is the term for an early or extra heartbeat that occurs when the heart's lower chambers contract out of sequence?

The correct term for an early or extra heartbeat that occurs when the heart's lower chambers contract out of sequence is "premature ventricular contraction." This condition, often abbreviated as PVC, is characterized by an abnormal heartbeat that originates in the ventricles. A PVC usually interrupts the normal rhythm of the heart, causing a sensation of a skipped beat or an additional heartbeat. It occurs when the muscular walls of the ventricles contract earlier than expected, leading to a feeling of unease or palpitation in the patient.

In contrast, other terms such as arrhythmia refer more broadly to any irregular heartbeat, which can encompass PVCs and many other irregularities. Atrial fibrillation specifically refers to a condition where the atria beat chaotically and irregularly, failing to coordinate with the ventricles, which is different from the concept of a single premature beat. Ventricular tachycardia describes a rapid heartbeat predominantly originating from the ventricles and often involves multiple consecutive heartbeats, rather than the isolated occurrence typical of a PVC. Understanding these distinctions is crucial for identifying and managing different cardiac conditions.