**Question:** Drug of choice in PSVT is

A. Amiodarone
B. Sotalol
C. Disopyramide
D. Verapamil

**Correct Answer: A. Amiodarone**

**Core Concept:** Paroxysmal Supraventricular Tachycardia (PSVT) is a type of supraventricular tachycardia (SVT) characterized by rapid heartbeats originating from the atrioventricular (AV) node or its surrounding tissues. The goal of treatment is to terminate the arrhythmia and restore sinus rhythm.

**Why the Correct Answer is Right:** Amiodarone is a class III antiarrhythmic drug with antiarrhythmic properties, which make it effective in treating various types of arrhythmias, including PSVT. It works by blocking the re-entry mechanisms responsible for arrhythmias, prolonging the action potential duration and refractory period of the cardiac cells. This results in a decrease in the conduction velocity and an increase in the effective refractory period, leading to the termination of the arrhythmia.

**Why Each Wrong Option is Incorrect:**

**B. Sotalol:** Sotalol is a class III antiarrhythmic drug, but it is not as effective as amiodarone in treating PSVT. Additionally, sotalol has beta-blocking properties, which might cause unwanted side effects in some patients.

**C. Disopyramide:** Disopyramide is a class Ic antiarrhythmic drug, which works by blocking the re-entry mechanisms responsible for arrhythmias. However, it is less effective than amiodarone and sotalol in treating PSVT.

**D. Verapamil:** Verapamil is a calcium channel blocker, which works by blocking the influx of calcium ions into the cardiac cells. However, it is less effective than amiodarone and sotalol in treating PSVT. Additionally, verapamil has beta-blocking properties, which might cause unwanted side effects in some patients.

**Clinical Pearl:** In cases where amiodarone is not available or contraindicated, sotalol can be used as an alternative. However, other options, such as verapamil and disopyramide, are less effective and might cause unwanted side effects.

**Core Concept:** Paroxysmal supraventricular tachycardia (PSVT) is an arrhythmia characterized by rapid heart rate and is caused by re-entrant pathways within the atria or atrioventricular (AV) node. The goal of treatment is to restore sinus rhythm and block the re-entrant circuit causing the arrhythmia.

**Why the Correct Answer is Right:** Amiodarone is a potent antiarrhythmic drug with a broad range of properties, including class III (prolongation of the action potential duration), class Ia (anti-arrhythmic), and class III (beta-blocking) effects. Amiodarone is the most effective drug for terminating PSVT due to its multi-