What should be done if adenosine does not work for SVT?

• A. Begin synchronized cardioversion immediately
• B. Repeat 6 mg after 1 hour
• C. Administer 12 mg rapid IV push
• D. Switch to beta-blocker infusion

Answer: (C)

When treating SVT with adenosine, the drug works by briefly blocking AV nodal conduction to interrupt the reentrant circuit. If the first rapid IV dose doesn’t terminate the rhythm, the next step is to give a second, higher dose of adenosine (12 mg) as a rapid IV push. The short half-life of adenosine makes a second dose a practical next move to increase the chance of conversion without waiting a long time. If there’s still no response after the second dose, management should shift to other options based on the patient's stability, such as synchronized cardioversion if unstable, or alternative IV antiarrhythmics like calcium channel blockers or beta-blockers as appropriate. Repeating the same dose after a long delay is not indicated, and immediately switching to a beta-blocker infusion isn’t the standard next step in a stable patient after adenosine failure.