After vagal maneuvers, which medication is commonly used to terminate SVT?

• A. Adenosine
• B. Lidocaine
• C. Aspirin
• D. Heparin

Answer: (A)

SVT that relies on AV nodal conduction can be stopped by a drug that temporarily blocks the AV node. Adenosine does exactly this: it activates A1 receptors in the AV node, causing a brief AV nodal block that often interrupts the reentrant circuit causing the SVT and restores a normal rhythm. Its effect is very short because of a rapid half-life, so it’s given as a rapid IV push with immediate monitoring and readiness to manage a transient pause or chest discomfort. After vagal maneuvers, it’s the preferred first-line medication for stable narrow-complex SVT because it can terminate the event quickly and safely.

Lidocaine targets ventricular tissue and is used for ventricular arrhythmias, not AV nodal–dependent SVT. Aspirin is for ischemia management and does not affect SVT. Heparin is an anticoagulant used in thromboembolic situations and likewise won’t terminate SVT.