Which drug is commonly used for acute termination of stable SVT due to its rapid onset and short half-life?

Which drug is commonly used for acute termination of stable SVT due to its rapid onset and short half-life?

• A. Digoxin
• B. Lidocaine
• C. Adenosine
• D. Amiodarone

Answer: (C)

The key idea here is treating stable supraventricular tachycardia with a medication that acts quickly and is cleared quickly, so you can terminate the reentrant rhythm and reassess promptly. Adenosine is the drug of choice for acute termination of AV nodal–dependent SVTs because it has an extremely rapid onset and a very short half-life (often about 10 seconds). When given as a rapid IV bolus, it briefly activates A1 receptors in the atrioventricular (AV) node, increasing potassium conductance and causing a momentary AV nodal block. If the tachycardia is dependent on conduction through the AV node (as in many reentrant SVTs), this transient block interrupts the reentrant circuit and restores normal rhythm within seconds. Because its effects wear off so quickly, any arrhythmias that don’t terminate can be reassessed quickly and, if appropriate, a second dose can be given. Digoxin, while useful for rate control in atrial fibrillation or flutter, has a slow onset and is not suitable for immediate termination of SVT. Lidocaine targets ventricular tissue and is used for ventricular arrhythmias, not AV nodal–dependent SVT. Amiodarone can terminate some SVTs but has a slower onset and is not the preferred agent for rapid, acute termination of stable SVT. So, the rapid-onset, short-half-life profile makes adenosine ideal for this scenario.

The key idea here is treating stable supraventricular tachycardia with a medication that acts quickly and is cleared quickly, so you can terminate the reentrant rhythm and reassess promptly.

Adenosine is the drug of choice for acute termination of AV nodal–dependent SVTs because it has an extremely rapid onset and a very short half-life (often about 10 seconds). When given as a rapid IV bolus, it briefly activates A1 receptors in the atrioventricular (AV) node, increasing potassium conductance and causing a momentary AV nodal block. If the tachycardia is dependent on conduction through the AV node (as in many reentrant SVTs), this transient block interrupts the reentrant circuit and restores normal rhythm within seconds. Because its effects wear off so quickly, any arrhythmias that don’t terminate can be reassessed quickly and, if appropriate, a second dose can be given.

Digoxin, while useful for rate control in atrial fibrillation or flutter, has a slow onset and is not suitable for immediate termination of SVT. Lidocaine targets ventricular tissue and is used for ventricular arrhythmias, not AV nodal–dependent SVT. Amiodarone can terminate some SVTs but has a slower onset and is not the preferred agent for rapid, acute termination of stable SVT.

So, the rapid-onset, short-half-life profile makes adenosine ideal for this scenario.