Answer: AV nodal blocking medications
Explaination: WPW occurs when a person is born with an "accessory pathway" that can bypass the AV node and conduct action potentials straight from the atrium to the ventricle. Since the accessory pathway has a very short refractory period, it can conduct impulses from the atria to the ventricles at very fast rates (> 400 impulses per minute). If the AV nodal conduction is blocked using the AV nodal blocking medications, more conduction can occur through the accessory pathway. In certain arrhythmias like atrial fibrillation this can cause the ventricular rate to become dangerously fast. A good mneumonic to remember the AV nodal blocking medications is "ABCD" which stands for Adenosine, Beta-blockers, Calcium channel blockers, and Digoxin.