What mechanism is AVRT?

What mechanism is AVRT?

• A. Micro
• B. Macro
• C. Both
• D. None

Answer: (B)

Macroreentry describes a large reentrant circuit that travels around a substantial pathway, such as the AV ring, using the AV node-His-Purkinje axis as one limb and an accessory pathway as the other. In AVRT, the loop spans a broad region because the atrial tissue and ventricular tissue are connected by the accessory pathway, creating a circuit that travels around the AV ring rather than being confined to a tiny area. Microreentry would involve a very small rotor within scar or a confined focus, which is not how AVRT operates. Therefore, the mechanism is macroreentrant.

Macroreentry describes a large reentrant circuit that travels around a substantial pathway, such as the AV ring, using the AV node-His-Purkinje axis as one limb and an accessory pathway as the other. In AVRT, the loop spans a broad region because the atrial tissue and ventricular tissue are connected by the accessory pathway, creating a circuit that travels around the AV ring rather than being confined to a tiny area. Microreentry would involve a very small rotor within scar or a confined focus, which is not how AVRT operates. Therefore, the mechanism is macroreentrant.