Which combination best describes the slow pathway's conduction and repolarization characteristics?

Which combination best describes the slow pathway's conduction and repolarization characteristics?

• A. Slow conduction and fast repolarization
• B. Fast conduction and fast repolarization
• C. Slow conduction and slow repolarization
• D. Fast conduction and slow repolarization

Answer: (A)

In AV nodal reentry, two pathways within the AV node behave differently to support a reentrant circuit. The slow pathway transmits impulses more slowly because its tissue conducts via calcium-dependent mechanisms and has a narrower, less conductive path. Yet it recovers excitability sooner after activation, meaning it repolarizes relatively quickly. So the combination that best describes the slow pathway is slow conduction paired with fast repolarization (shorter refractory period). This fast repolarization allows the slow pathway to be ready again sooner, which is essential for sustaining the reentrant loop when the impulse travels retrogradely through the other pathway.

In AV nodal reentry, two pathways within the AV node behave differently to support a reentrant circuit. The slow pathway transmits impulses more slowly because its tissue conducts via calcium-dependent mechanisms and has a narrower, less conductive path. Yet it recovers excitability sooner after activation, meaning it repolarizes relatively quickly.

So the combination that best describes the slow pathway is slow conduction paired with fast repolarization (shorter refractory period). This fast repolarization allows the slow pathway to be ready again sooner, which is essential for sustaining the reentrant loop when the impulse travels retrogradely through the other pathway.