How does atrial flutter respond to adenosine?

Atrial Flutter Response to Adenosine

In atrial flutter, adenosine transiently slows the ventricular rate by temporarily blocking AV nodal conduction, which can assist in diagnosis, but does not terminate the arrhythmia itself. 1, 2

Mechanism of Action and Effects

• Adenosine selectively blocks AV nodal conduction through activation of A1 receptors in cardiac tissue, making it effective for terminating AV nodal re-entrant tachycardias but not atrial flutter 2
• When given during atrial flutter, adenosine causes transient AV block, which can:
  • Reveal the underlying flutter waves, aiding in diagnosis 1
  • Temporarily slow the ventricular rate, but not provide meaningful lasting rate control 1
  • Not terminate the atrial flutter mechanism itself 1

Diagnostic Utility

• Adenosine can help differentiate atrial flutter from other supraventricular tachycardias by revealing the characteristic flutter waves during transient AV block 2
• The observation of transient AV block with persistent atrial activity can help distinguish atrial flutter from AVNRT and AVRT 1

Potential Risks and Complications

• Caution: Adenosine can cause potentially dangerous responses in patients with atrial flutter, including: 3

  • Acceleration of ventricular response with 1:1 AV conduction, which may require emergency cardioversion 3, 4, 5
  • Prolonged bradyasystole and hypotension in some patients 3, 6
  • Nonsustained polymorphic ventricular tachycardias following administration 6

• Risk factors for adverse responses may include:

  • Pre-existing 2:1 AV block that evolves into 1:1 conduction 3
  • Concomitant use of certain medications like flecainide 7
  • Sepsis or other systemic illness 6

Clinical Recommendations

• Have resuscitation equipment readily available when administering adenosine to patients with suspected or known atrial flutter 3
• For rate control in atrial flutter, non-dihydropyridine calcium channel blockers (diltiazem or verapamil) or beta-blockers are generally preferred over adenosine for sustained effect 1
• If adenosine reveals atrial flutter, consider treatment with longer-acting AV nodal blocking agents for more lasting control of ventricular rate 1
• For definitive treatment of atrial flutter, synchronized cardioversion is more appropriate than adenosine 1

Dosing Considerations

• Standard dosing (6 mg rapid IV push, followed by 12 mg if needed) should be used cautiously in atrial flutter 2
• Reduced initial dose (3 mg) should be considered in patients taking dipyridamole or carbamazepine, those with transplanted hearts, or if given by central venous access 1
• Larger doses may be required for patients with significant blood levels of theophylline, caffeine, or theobromine 1