What is the defining ECG feature of atrial fibrillation?

Prepare for the Cleveland Clinic EKG Test with flashcards and multiple choice questions. Gain insights with hints and explanations. Ace your exam today!

Multiple Choice

What is the defining ECG feature of atrial fibrillation?

Atrial fibrillation shows chaotic atrial activity that prevents organized atrial depolarization, so there are no discrete P waves on the ECG. This leads to an irregularly irregular rhythm with highly variable R-R intervals because the ventricles are activated by the AV node in an unpredictable, beat-to-beat fashion. The QRS complexes are typically narrow unless there’s a concurrent conduction problem, but the hallmark is the lack of visible P waves combined with the irregular rhythm. Regular P waves with a regular rhythm would indicate sinus rhythm, not atrial fibrillation. A prolonged PR interval with normal AV conduction points to first-degree AV block. A QRS duration over 120 ms with AV dissociation suggests another rhythm disturbance, such as ventricular tachycardia or complete AV block with dissociated atrial activity, not atrial fibrillation.

Atrial fibrillation shows chaotic atrial activity that prevents organized atrial depolarization, so there are no discrete P waves on the ECG. This leads to an irregularly irregular rhythm with highly variable R-R intervals because the ventricles are activated by the AV node in an unpredictable, beat-to-beat fashion. The QRS complexes are typically narrow unless there’s a concurrent conduction problem, but the hallmark is the lack of visible P waves combined with the irregular rhythm.

Regular P waves with a regular rhythm would indicate sinus rhythm, not atrial fibrillation. A prolonged PR interval with normal AV conduction points to first-degree AV block. A QRS duration over 120 ms with AV dissociation suggests another rhythm disturbance, such as ventricular tachycardia or complete AV block with dissociated atrial activity, not atrial fibrillation.

More practice questions