What is a prominent characteristic of atrial flutter on an ECG?

Atrial flutter is distinctly characterized by the presence of a "sawtooth" waveform on an electrocardiogram (ECG), commonly referred to as the F-wave pattern. This pattern occurs due to the rapid, organized electrical activity in the atria, typically resulting in a rate of 240 to 340 beats per minute. The F-waves can be best visualized in the inferior leads (II, III, and aVF), where they appear as a series of undulating, regular waves. This feature distinguishes atrial flutter from other arrhythmias, primarily by the regularity and appearance of the waveforms rather than the rhythm's overall regularity or irregularity.

In contrast, irregularly irregular rhythm is more typical of atrial fibrillation. Elevated ST segments can indicate myocardial ischemia or infarction and are not a characteristic of atrial flutter. Similarly, a wide QRS complex is associated with ventricular arrhythmias or bundle branch blocks rather than atrial flutter, which typically has a normal QRS duration if the ventricular conduction system is intact. Therefore, recognizing the F-wave pattern on an ECG is crucial for accurately identifying atrial flutter.