What is the defining characteristic of atrial flutter?

• A. Rapid ventricular response
• B. Very rapid atrial tachycardia creating saw-toothed P waves
• C. Asystole
• D. Paroxysmal supraventricular tachycardia

Answer: (B)

Atrial flutter is characterized by a rapid and regular atrial rhythm that often displays a distinct pattern of electrical activity. The defining feature is the presence of very rapid atrial tachycardia, which leads to the development of characteristic saw-toothed P waves, often described as "F-waves." These F-waves are prominent in the inferior leads and are indicative of the atrial re-entry circuit that occurs in atrial flutter.

This rapid atrial activity can result in varying ventricular responses, making it important to assess how the ventricles respond; however, the hallmark of atrial flutter itself is primarily these saw-toothed F-waves rather than the ventricular rate. This differentiation helps in the clinical identification of atrial flutter and distinguishes it from arrhythmias with different waveforms or patterns. Other options do not specifically indicate the unique saw-tooth pattern or the atrial rhythm characteristic of atrial flutter.