What does fibrillation refer to in cardiac terms?

Fibrillation in cardiac terms refers to the chaotic, irregular contractions of muscle fibers, particularly in the heart. This condition can occur in the atria (atrial fibrillation) or the ventricles (ventricular fibrillation). During fibrillation, the electrical impulses that coordinate the heart’s rhythm become disordered, leading to a lack of efficient blood movement throughout the body.

Unlike a regular heart rhythm, where the heart beats in a predictable manner, fibrillation results in erratic pumping action, which can severely compromise the cardiovascular system. It is an emergency condition requiring prompt medical intervention, as ventricular fibrillation can lead to sudden cardiac arrest if not treated immediately.

The other options do not accurately describe fibrillation. Regular heart rhythm signifies a normal functioning heart, cardiac arrest indicates a complete halt in heart function, and improved blood flow does not relate to the disorganized activity seen in fibrillation. Thus, the correct interpretation of fibrillation aligns with the description of irregular contractions or impulses occurring within the heart.