What rhythm is indicated by a "sawtooth" appearance on an ECG?

A "sawtooth" appearance on an ECG is characteristic of atrial flutter. This distinct waveform is known as "F-waves" and is typically seen in leads II, III, and aVF, where they create a repetitive, jagged pattern resembling a saw's teeth.

Atrial flutter occurs when there is a re-entrant circuit within the atrium, typically around the tricuspid valve, resulting in a rapid and regular atrial rate. The sawtooth pattern is an important diagnostic feature that not only helps in identifying atrial flutter but also differentiates it from other arrhythmias based on its unique morphology.

Other rhythms, such as ventricular fibrillation, sinus tachycardia, and first-degree AV block, do not exhibit this specific sawtooth pattern. Ventricular fibrillation presents with chaotic, undulating waves without distinct patterns. Sinus tachycardia displays a normal P-wave, which is absent in atrial flutter, while first-degree AV block shows consistent PR intervals with normal morphology of atrial and ventricular complexes. Understanding these distinctions is crucial for accurate diagnosis and subsequent management of dysrhythmias.