What is the drug of choice for supraventricular tachycardia (SVT)?

• A. Adenosine
• B. Metoprolol
• C. Amiodarone
• D. Atropine

Answer: (A)

Adenosine terminates many narrow-complex SVTs because it briefly blocks conduction through the AV node, which is where the reentrant circuits causing SVT often depend. Its ultra-short half-life means the effect is immediate but very brief, so a rapid IV push (often followed by a saline flush) can stop the tachycardia within seconds and restore normal rhythm. If the first dose doesn’t work, a second dose may be given, but the overall goal is to interrupt the reentrant loop at the AV node quickly and safely.

Be prepared for a transient pause after administration and possible chest discomfort, flushing, or shortness of breath; these effects are typically short-lived. Adenosine is avoided or used with caution in patients with asthma or COPD due to potential bronchospasm, and it should be used with caution if WPW with pre-excitation is suspected because of rare risks of precipitating a more dangerous rhythm.

Other drugs have roles in different scenarios: a beta-blocker like metoprolol can slow AV nodal conduction but is not as rapid for acute termination; amiodarone is more suited to other tachyarrhythmias or refractory SVT; atropine increases AV nodal conduction and is used for bradycardia, not to terminate SVT.