What measure may be helpful before using adenosine for paroxysmal SVT?

What measure may be helpful before using adenosine for paroxysmal SVT?

• A. Vagal maneuvers
• B. Electrical cardioversion
• C. Beta-blocker infusion
• D. IV fluids

Answer: (A)

Vagal maneuvers, by briefly increasing parasympathetic tone, slow conduction through the AV node and can interrupt the reentrant circuit that causes many paroxysmal SVTs. In a stable patient, these noninvasive maneuvers (like Valsalva or, when appropriate, carotid sinus massage) can terminate the tachycardia or at least convert it to a rhythm where the underlying atrial activity is clearer. If the maneuver succeeds, adenosine may not be needed. If it fails, adenosine can be given with a higher likelihood of success because AV nodal conduction is already slowed. Electrical cardioversion is reserved for unstable patients, while beta-blocker infusions or IV fluids don’t specifically prepare the rhythm for adenosine and are not first-line steps in this scenario.

Vagal maneuvers, by briefly increasing parasympathetic tone, slow conduction through the AV node and can interrupt the reentrant circuit that causes many paroxysmal SVTs. In a stable patient, these noninvasive maneuvers (like Valsalva or, when appropriate, carotid sinus massage) can terminate the tachycardia or at least convert it to a rhythm where the underlying atrial activity is clearer. If the maneuver succeeds, adenosine may not be needed. If it fails, adenosine can be given with a higher likelihood of success because AV nodal conduction is already slowed. Electrical cardioversion is reserved for unstable patients, while beta-blocker infusions or IV fluids don’t specifically prepare the rhythm for adenosine and are not first-line steps in this scenario.