What describes atrial fibrillation?

Atrial fibrillation is characterized by an irregular and often rapid beating of the atria, the upper chambers of the heart. In this condition, the electrical signals in the atria become chaotic, leading to an uncoordinated contraction of the atrial muscles. This results in an inconsistent heart rhythm that can vary widely from one beat to the next, which is why it is described as "irregular."

This irregularity can lead to inefficient blood flow and increase the risk of blood clots forming in the atria, potentially resulting in strokes. Understanding the nature of atrial fibrillation is crucial for appropriate management and treatment to mitigate these risks.

Both the other options present descriptions that do not accurately capture the essence of atrial fibrillation. Uniform beating of the atria would imply a regular rhythm, which contradicts the defining characteristic of atrial fibrillation. Rapid contraction of the ventricles may occur in some cardiac conditions but is not specific to atrial fibrillation alone. Complete cessation of heart activity, known as cardiac arrest, is a separate and critical condition altogether, with significantly different implications and management strategies.