In atrial tachycardia ablation planning, what is the primary purpose of an activation map?

• A. To locate the earliest activation site for ablation
• B. To measure conduction velocity
• C. To delineate scar tissue
• D. To map the endocardial surface only

Answer: (A)

Activation mapping focuses on timing of electrical activation across the atrial tissue during tachycardia. By plotting when each region activates relative to a reference, you can see the wavefront’s spread and identify the point that activates first. That earliest activation site is the most likely origin or the critical part of the reentrant circuit, making it the best target for ablation. Delivering energy there interrupts the mechanism sustaining the tachycardia and often terminates it.

Other aspects like measuring conduction velocity or delineating scar tissue are valuable in different mapping contexts, but they’re not the primary goal of activation mapping for AT ablation. Activation mapping is typically used to localize the earliest activation and guide precise lesion placement; it isn’t limited to the endocardial surface, though endocardial mapping is most commonly used.