Drug of choice for maintenance therapy in PSVT is
**Core Concept**
Paroxysmal supraventricular tachycardia (PSVT) is a type of abnormal heart rhythm characterized by a rapid heart rate originating from the atria or the atrioventricular node. Maintenance therapy aims to prevent recurrence of PSVT episodes.
**Why the Correct Answer is Right**
The drug of choice for maintenance therapy in PSVT is a beta-blocker, specifically propranolol or metoprolol. These medications work by blocking the effects of the sympathetic nervous system on the heart, thereby reducing the frequency of PSVT episodes. Beta-blockers inhibit the beta-1 receptors in the heart, which decreases the heart rate and contractility, making it more difficult for PSVT to occur.
**Why Each Wrong Option is Incorrect**
**Option A:** Digoxin is not the drug of choice for maintenance therapy in PSVT. Although it can be used to convert PSVT to a normal sinus rhythm, it is not effective in preventing recurrence of PSVT episodes.
**Option B:** Verapamil is a calcium channel blocker that can be used to treat PSVT, but it is not the first-line agent for maintenance therapy. It works by inhibiting the L-type calcium channels in the heart, which slows conduction through the AV node.
**Option C:** Adenosine is a drug of choice for acute termination of PSVT, but it is not used for maintenance therapy. It works by transiently blocking AV nodal conduction, which converts the PSVT to a normal sinus rhythm.
**Clinical Pearl / High-Yield Fact**
Beta-blockers are the preferred agents for maintenance therapy in PSVT because they have a longer duration of action and can be effective in preventing recurrence of PSVT episodes.
**Correct Answer:** D.