What does the term multifocal indicate about PVCs?

The term "multifocal" in relation to premature ventricular contractions (PVCs) indicates that these irregular heartbeats originate from different areas within the ventricles. As a result, the PVCs display varying shapes on an electrocardiogram (ECG). Each PVC can have a distinct morphology, reflecting the different ectopic foci that are activating the ventricular myocardium at various sites. This diversity in shape suggests that multiple irritable ventricular sites are contributing to the early contractions, which is significant for diagnosis and treatment as it may indicate underlying cardiac issues.

In contrast, if PVCs were to all appear the same, it would imply that they are unifocal, originating from a single ectopic focus, which is not the case here. Occurrence in pairs does not define multifocality; such pairs could still arise from the same focus. Lastly, regularity in frequency does not pertain to whether PVCs are multifocal; they can occur sporadically regardless of frequency.