In inferior leads, how do P waves appear for counterclockwise vs clockwise typical flutter?

• A. Counterclockwise: negative P waves; Clockwise: positive P waves
• B. Counterclockwise: positive P waves
• C. Counterclockwise: biphasic
• D. Counterclockwise: no P waves

Answer: (A)

In atrial flutter, the visible atrial activity (flutter waves) reflects the direction of the reentrant activation around the atrial tissue. In inferior leads, the polarity of those flutter waves depends on whether the flutter circuit moves counterclockwise or clockwise. If the flutter rotates counterclockwise, the atrial activation vector moves away from the inferior leads, producing negative flutter waves in II, III, and aVF. If the flutter rotates clockwise, the activation moves toward the inferior leads, giving positive flutter waves in those same leads. So the typical pattern is negative flutter waves in inferior leads for counterclockwise flutter and positive flutter waves for clockwise flutter.