What therapy may be used to alleviate symptoms during SVT if vagal maneuvers are unsuccessful?

Adenosine is an effective first-line therapy for the acute management of supraventricular tachycardia (SVT) when vagal maneuvers have failed. It works by temporarily blocking atrioventricular (AV) node conduction, which can interrupt the reentrant circuit commonly responsible for SVT. This blockade can restore normal sinus rhythm almost immediately.

Administered via rapid IV push, adenosine is particularly useful in cases of paroxysmal SVT, and is preferred due to its rapid onset and short duration of action, allowing for quick assessment of its efficacy without prolonged effects. This property is advantageous in emergency settings where immediate rhythm control is required.

Other therapies, such as calcium channel blockers, digoxin, and beta-blockers, may also play a role in the management of SVT, particularly in chronic settings or for rate control. However, they are typically not used as the first-line treatment in acute situations where immediate rhythm stabilization is necessary.