**Core Concept:** Paroxysmal supraventricular tachycardia (PSVT) is a type of abnormal heart rhythm characterized by rapid, usually paroxysmal, atrial or atrioventricular reentrant tachycardia. The goal of medication in PSVT is to terminate the tachycardia and restore sinus rhythm.

**Why the Correct Answer is Right:** The drug of choice for PSVT is Class III antiarrhythmic drugs, specifically, the potassium channel blockers (sotalol or dofetilide). These agents block the rapid repolarization of atrial and ventricular myocytes, which slows down the conduction of the electrical impulse and terminates the tachycardia.

**Why Each Wrong Option is Incorrect:**

A. Class I antiarrhythmic drugs (e.g., lidocaine, procainamide) are not selective for atrial conduction and would not effectively terminate PSVT.

B. Class II antiarrhythmic drugs (e.g., beta-blockers) are not selective for atrial conduction and would not effectively terminate PSVT.

C. Class III antiarrhythmic drugs (e.g., amiodarone) are not as selective for atrial conduction as sotalol or dofetilide and may have significant side effects.

D. Calcium channel blockers (e.g., verapamil) are not effective in treating PSVT as they primarily affect ventricular conduction and have limited atrioventricular block.

**Clinical Pearl:** In PSVT, the heart rate can be reduced using beta-blockers (e.g., metoprolol) in case of hemodynamic compromise, but the primary treatment is with Class III antiarrhythmic drugs (sotalol or dofetilide) to specifically target atrial conduction and terminate the tachycardia.