Certified Rhythm Analysis Technician (CRAT) Practice Exam Prep & Study Guide

Atrial fibrillation is characterized by an irregular and often rapid heart rate that results from chaotic electrical signals in the atria. One of the hallmark features of this arrhythmia is the absence of distinct P waves on the electrocardiogram (ECG). Instead of clear P waves, what is seen is a wavy baseline, which is often referred to as fibrillatory waves. This lack of P waves reflects the disorganized electrical activity in the atria, leading to the irregularity of the rhythm seen in atrial fibrillation.

The other options reflect characteristics that do not align with atrial fibrillation. Regular R-R intervals are associated with more organized rhythms like sinus rhythm, while delta waves are typically found in conditions such as Wolff-Parkinson-White syndrome. A consistent PR interval would indicate a conduction delay or block, which does not occur in atrial fibrillation where the atrial activity is effectively chaotic. Therefore, the absence of P waves is the defining characteristic of this arrhythmia.