DM Neurology Common Merit List Rank 3

In WPW syndrome…there is stimulation of accessory pathway…so our primary aim should be to block SAN and AVN…so why is Digoxin contraindicated here??But IV Procainamide is the DOC which also causes AVN block…

Our aim is to block the accessory pathway not the main pathway like SAN or AVN. If main channels are blocked the transmission will occur more from the accessory pathway which will worsen the disease even more causing arrhythmias like VF.

Procainamide specifically acts on the accessory pathway and increase its refractoriness and thus inhibits transmission through these pathways and relieving the condition.

AV nodal blockers are contraindicated but a drug that blocks both AV node and accessory pathway can be used like procainamide.