In atrial flutter, what is the expected heart rate characteristic for P waves?

In atrial flutter, the defining characteristic of the P waves, which represent atrial activity, is the presence of organized, recurrent waves - often referred to as "flutter waves" or "F waves." The classic rate for these flutter waves is around 300 beats per minute (bpm). This results from the rapid reentrant circuit within the atria that generates a regular, repetitive electrical impulse.

When the atrial rate is around 300 bpm, it often corresponds to a ventricular response of 150 bpm when the atrioventricular (AV) node conducts the impulses in a 2:1 block. Understanding this characteristic allows healthcare providers to recognize atrial flutter on an electrocardiogram (ECG), where you would typically see the "sawtooth" pattern in the inferior leads (II, III, aVF) that signifies these flutter waves. This pattern is a hallmark indicator of atrial flutter, making it distinctive compared to other arrhythmias.