Atrial flutter is typically characterized by which finding on ECG?

• A. 1:1 AV conduction with narrow QRS
• B. Atrial rate 250-350 bpm with sawtooth F waves
• C. Wide QRS with ST elevations
• D. Atrial rate 350-450 bpm with irregular rhythm

Answer: (B)

Atrial flutter shows an organized atrial rhythm with rapid rates and characteristic sawtooth flutter waves on the ECG. The atrial rate is typically 250–350 beats per minute, producing those distinct flutter waves, usually best seen in the inferior leads. The ventricles respond through the AV node at a slower, fixed ratio (often 2:1), which gives a regular, narrow QRS complex and a ventricular rate around 150 bpm when the ratio is 2:1. The sawtooth pattern and the specific atrial rate help differentiate flutter from other tachyarrhythmias.

Other patterns don’t fit as well: a 1:1 AV conduction would push the ventricular rate very high and is uncommon; wide QRS with ST elevations points to a different cardiac issue like ischemia or bundle branch block; an atrial rate of 350–450 bpm with an irregular rhythm suggests atrial fibrillation rather than flutter, which is usually more organized with a more regular rhythm when conduction is constant.