What is atrial fibrillation characterized by on an EKG?

Atrial fibrillation is characterized by an irregularly irregular heart rhythm that lacks distinct P waves on an electrocardiogram (EKG). In this condition, the atria experience chaotic electrical signals, leading to an uncoordinated and rapid contraction of the atrial muscle. As a result, the organized contraction that typically produces P waves is absent, giving the EKG a characteristic appearance.

The irregularly irregular rhythm means that the intervals between the heartbeats (R-R intervals) vary unpredictably, which is a key feature of atrial fibrillation. The absence of clear and distinct P waves is critical for the identification of this arrhythmia, as it indicates that the normal conduction pathway has been disrupted.

In contrast, options that refer to a regular heart rhythm with distinct P waves, normal sinus rhythm, or consistent R-R intervals are indicative of other arrhythmias or cardiac conditions rather than atrial fibrillation. Therefore, the presence of an irregularly irregular rhythm with no distinct P waves on the EKG is definitive for diagnosing atrial fibrillation.