Which rhythm is characterized by no P wave and an irregularly regular pattern?

Atrial fibrillation is characterized by the absence of identifiable P waves and an irregularly irregular rhythm. In this condition, the electrical impulses in the atria are chaotic, leading to disorganized atrial activity. This results in the absence of distinct P waves on the ECG, which are normally produced during the electrical depolarization of the atria. Instead, there may be small, erratic fluctuations known as fibrillatory waves.

The term "irregularly irregular" refers to the unpredictability in the timing of the QRS complexes, which indicate ventricular depolarization. This lack of regular pattern is a hallmark sign of atrial fibrillation, distinguishing it from other arrhythmias that may present with more organized rhythms or distinguishable P waves. This unique presentation is crucial for healthcare professionals when diagnosing and determining the appropriate management for patients with atrial fibrillation.