What is the primary characteristic of atrial fibrillation?

Atrial fibrillation is primarily characterized by an irregularly irregular heart rhythm without distinct P waves on an electrocardiogram (ECG). In this condition, the electrical signals in the atria become chaotic, leading to ineffective contraction of the atria and resulting in a rapid and disorganized heart rhythm. This absence of distinct P waves is a key diagnostic feature, as it indicates the loss of organized atrial depolarization.

The irregularity of the rhythm is notable because it does not follow a predictable pattern, which is a departure from more organized rhythms such as sinus rhythm where P waves are clearly seen and occur at regular intervals. The nature of atrial fibrillation can lead to potential complications, such as blood clots forming in the atria due to stagnant blood flow, increasing the risk of stroke.

In summary, understanding that atrial fibrillation is defined by its irregularly irregular rhythm and the absence of distinct P waves is crucial for proper identification and management of this dysrhythmia.