Which of the following describes Typical Flutter's ECG/EGM characteristics?

• A. CTI-dependent flutter with counterclockwise or clockwise rotation and concentric activation
• B. Eccentric activation and AVN involvement
• C. LVOT dependent
• D. Parasternal location near AVN

Answer: (A)

Typical flutter is a macroreentrant atrial tachycardia that uses the cavo-tricuspid isthmus as the critical corridor. The activation propagates in a circular path around the tricuspid annulus, which in the right atrium appears as concentric activation; the circuit can rotate either counterclockwise or clockwise, leading to the characteristic flutter waves seen on ECG. Because the CTI is essential to sustaining the loop, ablation at this isthmus often terminates the tachycardia.

Other descriptions imply activation patterns or locations not seen in typical flutter: eccentric activation with involvement of the AV node suggests an atypical flutter or another nodal-reentrant tachycardia, while LVOT dependency or a parasternal site near the AV node would point to non-atrial–centric mechanisms, not typical flutter.