What is the classic ECG appearance of atrial flutter?

• A. Sawtooth flutter waves around 250–350 bpm
• B. Irregularly irregular baseline with no discernible P waves
• C. Prolonged PR interval with positive P waves
• D. Delta waves

Answer: (A)

The main concept is that atrial flutter creates a rapid, organized atrial rhythm that manifests as sawtooth flutter waves on the ECG. The atrial rate is typically about 250–350 beats per minute, which replaces the normal P waves with these flutter waves. The ventricular rate depends on AV conduction and is often around 150 bpm with 2:1 conduction, though other conduction ratios can occur. The sawtooth pattern is most clearly seen in leads II, III, aVF and sometimes V1. This pattern helps distinguish atrial flutter from other rhythms: atrial fibrillation shows an irregularly irregular rhythm with no clear P waves, first-degree AV block shows a prolonged PR interval with normal-appearing P waves, and delta waves point to pre-excitation syndromes like WPW.