What characterizes atrial flutter?

Atrial flutter is characterized by rapid atrial contractions that produce a distinctive sawtooth pattern, often referred to as "F-waves" or "flutter waves." This pattern is seen on an electrocardiogram (ECG), where the atria contract at a high rate, typically between 240 to 340 beats per minute. The organized, rhythmic nature of these atrial contractions is what distinguishes atrial flutter from other arrhythmias, such as atrial fibrillation, where there is a more chaotic and irregular rhythm seen.

The sawtooth appearance often shows up best in the inferior leads (II, III, aVF) on an ECG, providing a visual cue that is critical for diagnosis. Understanding this characteristic pattern helps healthcare professionals identify atrial flutter quickly, which can influence treatment decisions and patient management.

The other options reflect different arrhythmias or characteristics that do not accurately describe atrial flutter, thereby reinforcing why the first choice is the defining feature.