In patients with Wolff-Parkinson-White (WPW) syndrome, what medication is contraindicated?

In patients with Wolff-Parkinson-White (WPW) syndrome, adenosine is contraindicated primarily due to its potential to worsen the rapid atrial rates associated with WPW. In WPW, there is an accessory pathway that can conduct impulses faster than the normal conduction system, which can lead to re-entrant tachycardias. Adenosine, while useful in other forms of supraventricular tachycardia by temporarily blocking the AV node, can inadvertently facilitate the conduction via the accessory pathway. This could result in an even faster ventricular response, leading to severe tachycardia and hemodynamic instability.

In contrast, the other medications listed, such as lidocaine and amiodarone, may be used in WPW under particular circumstances, especially when dealing with ventricular arrhythmias. Epinephrine can also be used, but it must be administered cautiously as it could exacerbate tachycardia. Understanding the dynamics of WPW and the role of these medications is crucial for effective management in emergency situations.