What is the protocol for an adenosine (adenosine) challenge to diagnose supraventricular tachycardia (SVT)?

From the Guidelines

To perform an adenosine challenge for SVT, start with 6 mg of adenosine given as a rapid IV push over 1-2 seconds, followed immediately by a 20 mL saline flush, as recommended by the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1. If the first dose is ineffective after 1-2 minutes, administer 12 mg as a second dose. Key considerations for the adenosine challenge include:

• Ensuring continuous cardiac monitoring during administration, as adenosine causes a brief period of asystole (typically 3-10 seconds) 1.
• Having resuscitation equipment readily available, though serious adverse effects are rare due to adenosine's extremely short half-life (less than 10 seconds) 1.
• Warning the patient about transient symptoms including chest pressure, flushing, dyspnea, and a sense of impending doom 1.
• Understanding that adenosine works by activating potassium channels in the AV node, hyperpolarizing the cells and temporarily blocking conduction, which can terminate reentry circuits in AVNRT (AV nodal reentrant tachycardia) or reveal underlying atrial activity in other arrhythmias, making it both diagnostic and therapeutic 1.
• Recognizing contraindications such as severe asthma, second or third-degree heart block without a pacemaker, and sick sinus syndrome 1. The most recent and highest quality study, the 2015 ACC/AHA/HRS guideline 1, supports the use of adenosine as a first-line treatment for SVT, highlighting its effectiveness and safety profile.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Adenosine Challenge for SVT

• The adenosine challenge is a diagnostic and therapeutic procedure used to treat supraventricular tachycardia (SVT) 2, 3, 4, 5, 6.
• The standard dosing regimen for adenosine is 6 mg, 12 mg, and 12 mg, but higher doses may be necessary in some cases 2, 3.
• Adenosine works by causing a transient heart block, which can help terminate SVT 2, 4, 5.
• The effectiveness of adenosine in terminating SVT has been shown to be high, with success rates ranging from 80-93% 4, 5.
• Adenosine has a rapid onset of action, with an average time to termination of tachycardia of 30 seconds 4.
• Common side effects of adenosine include chest discomfort, dyspnea, and flushing, but these are usually short-lived and mild 4, 5.

Dosing and Administration

• The initial dose of adenosine is typically 6 mg, given as an intravenous bolus 4, 5.
• If the initial dose is not effective, additional doses of 12 mg may be given 4, 5.
• In some cases, higher doses of adenosine may be necessary, such as 18 mg or 24 mg 2, 3.
• Adenosine should be administered under close monitoring, with electrocardiographic and hemodynamic monitoring 2, 5.

Patient Selection and Safety

• Adenosine is generally safe and effective for patients with SVT, but it may not be suitable for patients with certain underlying medical conditions, such as heart failure or wide-complex tachycardia 5.
• Patients with SVT should initially be treated using vagotonic physical maneuvers, and adenosine should be reserved for patients who do not respond to these maneuvers or who have contraindications to other treatments 5.
• Adenosine has a low risk of serious side effects, but it can cause atrial fibrillation in some patients, particularly those with AVRT or AT 6.