What is the atrial rate in atrial fibrillation?

In atrial fibrillation, the atrial rate is often rapid and chaotic due to disorganized electrical activity in the atria. This condition typically results in an atrial rate that can exceed 350 beats per minute. The lack of coordinated atrial contraction leads to this extremely high rate as multiple foci in the atria fire impulses simultaneously, creating a situation where the atria quiver rather than contract effectively.

When considering the other options, an atrial rate between 100-150 bpm is more characteristic of atrial flutter rather than atrial fibrillation. The range of 200-300 bpm also typically suggests atrial flutter or other arrhythmias. Lastly, an atrial rate of less than 100 bpm does not align with the rapid electrical activity observed in atrial fibrillation. Thus, the distinctive characteristic of atrial fibrillation is the chaotic and often greater than 350 bpm atrial rate.