Which statement about adenosine dosing for acute SVT is true?

• A. 6 mg IV push; may repeat with 12 mg; brief AV block with return to rhythm
• B. 12 mg IV push; immediate rhythm change
• C. 3 mg IV push; no repeats
• D. 1 mg IV push; no AV block

Answer: (A)

Adenosine terminates acute SVT by briefly blocking the AV node, which interrupts the reentrant circuit that depends on AV nodal conduction and often resets the rhythm to normal. Because its effects are so short-lived, it must be given as a rapid IV bolus with a quick saline flush to reach the heart promptly.

Begin with a 6 mg IV push. If there’s no conversion within about 1–2 minutes, repeat with a 12 mg IV push. A second 12 mg dose can be given if needed. A typical result is a transient AV block or pause during the conversion, followed by return to sinus rhythm.

This dosing pattern—6 mg initial, possibly followed by 12 mg—reflects the standard approach and the expected short-acting action with occasional brief AV nodal block as the rhythm converts.