Verapamil Dosing for Supraventricular Tachycardia (SVT)
For acute treatment of SVT, intravenous verapamil should be administered at a dose of 5-10 mg (0.075-0.15 mg/kg) as a slow IV bolus over at least 2 minutes under continuous ECG and blood pressure monitoring. 1
Acute Management Algorithm
- First-line treatment for hemodynamically stable SVT should be vagal maneuvers 2
- Adenosine is the recommended second-line agent for acute termination of SVT due to its rapid action and short half-life 2, 3
- Verapamil is an appropriate third-line agent when adenosine fails or is contraindicated 2, 3
- For hemodynamically unstable SVT, synchronized cardioversion is recommended rather than pharmacological therapy 2
Verapamil IV Dosing Protocol
- Initial dose: 5-10 mg (0.075-0.15 mg/kg) administered as an IV bolus over at least 2 minutes 3, 1
- For older patients, administer over at least 3 minutes to minimize risk of adverse effects 1
- If no response to initial dose, an additional 10 mg (0.15 mg/kg) can be given 30 minutes after the first dose 3, 1
- Maximum total dose should not exceed 20-30 mg 1
- Administration must be performed under continuous ECG and blood pressure monitoring 1
Contraindications and Precautions
Verapamil is contraindicated in patients with:
- AV block greater than first degree (unless pacemaker present) 3
- SA node dysfunction 3
- Decompensated heart failure or severe LV dysfunction 3
- Hypotension 3
- Wolff-Parkinson-White syndrome with atrial fibrillation/flutter 3, 4
- Cardiogenic shock 3
- Wide-complex tachycardias unless known with certainty to be supraventricular 4
Caution in patients who have recently received β-blockers due to risk of profound bradycardia and hypotension 3
Management of Adverse Effects
- Hypotension is the most common adverse effect of verapamil 3, 4
- Consider calcium pretreatment (1g IV calcium salt) to prevent verapamil-induced hypotension in patients with borderline blood pressure 5, 6
- Have resuscitation equipment available during administration 3
- Monitor for bradycardia and worsening heart failure in predisposed patients 3
Long-Term Oral Management
- For ongoing management of recurrent SVT, oral verapamil can be initiated at 120 mg daily 3
- Dose can be titrated up to a maximum of 480 mg daily in divided doses or as a single dose with long-acting formulations 3, 7
- Oral verapamil has demonstrated effectiveness in prophylaxis of paroxysmal SVT, particularly in AV nodal re-entry tachycardia 7
Clinical Pearls
- Verapamil works by slowing AV node conduction and increasing AV node refractoriness 3, 1
- Verapamil is more effective in SVT due to AV nodal re-entry than in SVT due to concealed accessory pathway 7
- For intractable SVT after cardiac surgery, continuous infusion of verapamil (0.11 ± 0.05 mg/kg/h) with ventricular pacing has shown good results 8