When mapping a bypass tract, the location of the pathway is inferred by identifying which chamber activation timing?

When mapping a bypass tract, the location of the pathway is inferred by identifying which chamber activation timing?

• A. The chamber activated first
• B. The chamber activated last
• C. The chamber with the shortest AV nodal delay
• D. The chamber with the longest conduction time

Answer: (A)

Mapping a bypass tract relies on where activation occurs first. The accessory pathway provides a shortcut between atrial and ventricular tissue, bypassing the AV node, so the impulse reaches its insertion site earlier than the surrounding tissue. The chamber that activates first reveals the tract’s location, guiding precise ablation. Activation last would point to a downstream area, not the tract; the shortest AV nodal delay or the longest conduction time describe nodal or tissue properties, not the specific insertion site of the bypass tract.

Mapping a bypass tract relies on where activation occurs first. The accessory pathway provides a shortcut between atrial and ventricular tissue, bypassing the AV node, so the impulse reaches its insertion site earlier than the surrounding tissue. The chamber that activates first reveals the tract’s location, guiding precise ablation. Activation last would point to a downstream area, not the tract; the shortest AV nodal delay or the longest conduction time describe nodal or tissue properties, not the specific insertion site of the bypass tract.