Which of the following arrhythmias typically has a distinctive "sawtooth" pattern in the atrial activity?

Atrial flutter is characterized by a distinctive "sawtooth" pattern in the atrial activity, often referred to as "F-waves" or "flutter waves." These waves occur due to a reentrant circuit in the atria, leading to a rapid and organized atrial contraction. This pattern is most noticeable in the inferior leads (II, III, and aVF), where the sawtooth appearance is particularly clear.

In contrast, atrial fibrillation presents with a more chaotic and irregular atrial activity, lacking any organized rhythm or pattern. Ventricular fibrillation is also disorganized and lethal, with no discernible waveforms, while supraventricular tachycardia is characterized by a rapid heart rate and can show narrow QRS complexes but does not display the sawtooth pattern indicative of atrial flutter. Thus, recognizing the sawtooth pattern is crucial in diagnosing atrial flutter accurately.