Which region is most commonly ablated during typical atrial flutter ablation?

• A. Cavotricuspid isthmus
• B. Interatrial septum
• C. Coronary sinus ostium
• D. Left atrial appendage

Answer: (A)

Typical atrial flutter is a macroreentrant circuit that travels around the tricuspid annulus in the right atrium. The critical isthmus sustaining this loop is the cavotricuspid isthmus—the narrow passage between the inferior vena cava and the tricuspid valve. Ablation across this isthmus creates a durable bidirectional block, interrupting the reentrant circuit and stopping the flutter. That’s why this region is the standard target for typical flutter ablation.

Other regions don’t fit the usual flutter mechanism: the interatrial septum is not the key path for this right atrial circuit, the coronary sinus ostium is a venous landmark rather than part of the reentrant pathway, and the left atrial appendage belongs to the left atrium and is more relevant to left‑sided arrhythmias like atrial fibrillation, not typical flutter ablation.