What occurs during the "sawtooth" pattern on an ECG?

The "sawtooth" pattern on an ECG is characteristic of atrial flutter. This pattern, often referred to as "F-waves," appears as a series of regular, sawtooth-like waves, typically best observed in the inferior leads (II, III, and aVF). These waves occur due to a reentrant circuit in the right atrium, where the atria contract in a rapid and organized manner, producing a distinctive rhythmic pattern.

In atrial flutter, the atrial rate usually ranges from 240 to 340 beats per minute, which is significantly faster than normal sinus rhythm. While there can be a variable response in the ventricular rate depending on how many atrial impulses are conducted through the AV node, the presence of the sawtooth pattern is a clear identifier of this specific arrhythmia. Understanding this pattern is crucial for identification and management in clinical practice, as atrial flutter can lead to complications such as thromboembolism if left untreated.