Final answer:
Verapamil is contraindicated in patients with WPW syndrome because it can exacerbate underlying conduction abnormalities and lead to dangerous arrhythmias. Potassium channel blockers like amiodarone affect the repolarization phase, influencing the T wave on an ECG.
Step-by-step explanation:
The question concerns contraindications for a patient with Wolff-Parkinson-White (WPW) syndrome. People with WPW syndrome have an extra electrical pathway in the heart, leading to periods of rapid heart rate (tachycardia). Certain medications can be dangerous to use in these patients. Specifically, the medication of concern here as a contraindication is Verapamil. Verapamil is a calcium channel blocker and can exacerbate the underlying conduction abnormalities in patients with WPW syndrome, potentially leading to life-threatening arrhythmias.
Potassium channel blockers, such as amiodarone, impede the movement of K+ through voltage-gated K+ channels in the cardiac action potential. This can affect the repolarization phase of the action potential, which is reflected on the ECG as the T wave.