In a stable, regular narrow-complex tachycardia, what is a common first-line pharmacologic therapy?

In a stable, regular narrow-complex tachycardia, what is a common first-line pharmacologic therapy?

• A. Metoprolol IV
• B. Amiodarone IV
• C. Adenosine 6 mg IV push (can repeat 12 mg)
• D. Verapamil IV

Answer: (C)

In stable, regular narrow-complex tachycardia the first-line pharmacologic move is adenosine. It works by briefly blocking conduction through the AV node, which is the critical part of the reentrant circuit in most SVTs like AV nodal reentrant tachycardia. Because adenosine has an extremely short half-life, it acts quickly and, if the tachycardia is AV nodal dependent, often terminates it or at least reveals the underlying rhythm within seconds. The usual approach is a rapid IV push of 6 mg, which can be followed by a 12 mg dose if needed, with saline flush to ensure it reaches the heart promptly. Its rapid action and diagnostic value make it the best initial choice for these cases. Other drugs can be used if adenosine is ineffective or contraindicated, but they don’t offer the same combination of speed, targeted mechanism, and safety in stable AV nodal–dependent SVT.

In stable, regular narrow-complex tachycardia the first-line pharmacologic move is adenosine. It works by briefly blocking conduction through the AV node, which is the critical part of the reentrant circuit in most SVTs like AV nodal reentrant tachycardia. Because adenosine has an extremely short half-life, it acts quickly and, if the tachycardia is AV nodal dependent, often terminates it or at least reveals the underlying rhythm within seconds. The usual approach is a rapid IV push of 6 mg, which can be followed by a 12 mg dose if needed, with saline flush to ensure it reaches the heart promptly. Its rapid action and diagnostic value make it the best initial choice for these cases. Other drugs can be used if adenosine is ineffective or contraindicated, but they don’t offer the same combination of speed, targeted mechanism, and safety in stable AV nodal–dependent SVT.