What is the recommended dose of adenosine for supraventricular tachycardia (SVT)?

Adenosine Dosing for Supraventricular Tachycardia

The recommended dose of adenosine for supraventricular tachycardia (SVT) is an initial 6 mg rapid IV bolus, followed by 12 mg if no response within 1-2 minutes, with the option to repeat the 12 mg dose once more if necessary. 1

Administration Technique

Proper administration is critical for effectiveness:

• Administer as a rapid IV bolus over 1-2 seconds
• Inject as proximal or as close to the heart as possible
• Follow immediately with a rapid saline flush
• Monitor ECG continuously during administration

Dosing Algorithm

1. First dose: 6 mg rapid IV bolus
2. Second dose: If no response after 1-2 minutes, administer 12 mg rapid IV bolus
3. Third dose: If still no response after 1-2 minutes, may repeat 12 mg dose once more

The American College of Cardiology/American Heart Association/Heart Rhythm Society guidelines note that the safe use of 18-mg bolus doses has been reported, though this is not typically included in the standard dosing algorithm. 1

Special Populations and Considerations

• Reduced initial dose (3 mg) is recommended for:

  • Patients taking dipyridamole or carbamazepine
  • Heart transplant recipients
  • When administered via central venous access 1, 2

• Increased initial dose may be required for:

  • Patients with significant blood levels of theophylline, caffeine, or theobromine 1

Potential Adverse Effects

Common side effects are usually transient due to adenosine's very short half-life (0.6-10 seconds) 3:

• Flushing
• Chest pain/discomfort
• Dyspnea
• Transient AV block
• Hypotension

Precautions and Contraindications

Adenosine should be used with caution or avoided in:

• Patients with asthma or bronchospastic lung disease (contraindicated) 1
• Patients with pre-excitation syndromes (risk of accelerated conduction through accessory pathway) 1
• Second or third-degree AV block (unless patient has functioning pacemaker) 4

Efficacy

Adenosine is highly effective for SVT involving the AV node:

• 90-95% effectiveness for AVNRT and AVRT 2
• Variable effectiveness for focal atrial tachycardia depending on the mechanism 1
• Rapid onset of action (approximately 30 seconds) 5

Comparison with Alternative Treatments

While calcium channel blockers (verapamil, diltiazem) and beta-blockers can also be effective for SVT, adenosine offers advantages:

• More rapid onset of action
• Extremely short half-life, allowing for quick recovery if adverse effects occur
• No significant negative inotropic effects (unlike verapamil) 1

Adenosine should be considered first-line therapy for acute termination of stable SVT, with vagal maneuvers attempted first when appropriate. 1