Which statement best describes how activation maps are used in ablation planning?

• A. To measure tissue conduction velocity
• B. To locate the latest activation site
• C. To locate the earliest activation site
• D. To map only anatomical geometry

Answer: (C)

Activation maps show when different parts of the heart activate during an arrhythmia, typically with a color-coded timeline. In planning ablation, the goal is to interrupt the source or critical pathway that sustains the abnormal rhythm. The site that activates first—earliest activation—is usually the origin from which the impulse spreads. Ablating at this earliest point can stop the wavefront from propagating and often terminates the arrhythmia or prevents it from starting again.

Late activation sites do not best represent the source of initiation, and simply mapping anatomical geometry misses the crucial timing information. While you can estimate how fast waves travel from timing differences, the primary purpose of the activation map is to locate where activation begins, guiding effective ablation.