Atrial fibrillation is characterized by which of the following?

Atrial fibrillation is defined by the presence of multiple electrical impulses being generated within the atria of the heart. This condition leads to disorganized and rapid heartbeats, as the normal rhythmic contractions are disrupted. In atrial fibrillation, the atria do not contract effectively and instead quiver or fibrillate, which contributes to an irregular and often rapid heartbeat. This chaotic electrical activity prevents the atria from pumping blood efficiently into the ventricles, potentially leading to various complications, including blood clots and stroke.

The other options do not accurately describe atrial fibrillation. For instance, slow, regular heartbeats characterize different types of arrhythmias, while rapid electrical impulses from the ventricles may occur in other conditions but do not specifically define atrial fibrillation. The consistent conduction of impulses to the ventricles implies a regular, organized pattern, which is contrary to the nature of atrial fibrillation.