What is the recommended dose of Diltiazem (diltiazem) for Paroxysmal Supraventricular Tachycardia (PSVT)?

Diltiazem Dosing for Paroxysmal Supraventricular Tachycardia (PSVT)

For PSVT, the recommended initial dose of intravenous diltiazem is 0.25 mg/kg (15-20 mg for average adult) administered over 2 minutes, with an additional dose of 0.35 mg/kg (20-25 mg) after 15 minutes if needed, followed by a maintenance infusion of 5-15 mg/hour if necessary. 1, 2

Initial Management Algorithm

First-line Treatment:

• Adenosine is typically the first-line agent for stable PSVT due to its rapid action and short half-life 1
• If adenosine fails or is contraindicated, diltiazem is an excellent second-line option 1

Diltiazem IV Bolus Dosing:

• Initial dose: 0.25 mg/kg (approximately 15-20 mg for an average adult) administered over 2 minutes 1, 2
• Follow-up dose: If inadequate response after 15 minutes, give 0.35 mg/kg (approximately 20-25 mg) over 2 minutes 1, 2
• Studies show 100% conversion rate with the 0.25 mg/kg dose compared to only 25% with placebo 3

Continuous Infusion (if needed):

• Starting rate: 5-10 mg/hour 1, 2
• Titration: May increase in 5 mg/hour increments up to 15 mg/hour as needed 1, 2
• Duration: May be maintained for up to 24 hours 2

Efficacy and Special Considerations

Efficacy:

• Diltiazem has shown superior efficacy compared to esmolol in terminating PSVT (100% vs 25% response rate) 4
• When the first bolus is ineffective, a second bolus given after 5 minutes usually succeeds 4
• Conversion rates of 82-100% have been reported with doses between 0.15-0.45 mg/kg 3, 5

Cautions and Contraindications:

• Avoid in patients with:
  • Heart failure or impaired ventricular function 1
  • Hypotension 1
  • Pre-excited atrial fibrillation or flutter (WPW syndrome) 1
  • AV block greater than first degree 1
  • Sinus node dysfunction (without pacemaker) 1

Side Effects to Monitor:

• Hypotension (most common adverse effect) 1, 6
• Bradycardia 1, 7
• Worsening heart failure in predisposed patients 1

Special Populations

Elderly Patients:

• Consider starting with a lower dose (≤0.2 mg/kg) in elderly patients 6, 7
• Lower doses may provide similar efficacy with reduced risk of hypotension 6
• In one study of elderly patients (mean age 70 years), diltiazem was effective and safe when used carefully 7

Maintenance Therapy:

• For long-term oral management after conversion, diltiazem can be given at 120 mg daily (divided or single dose with long-acting formulations) 1
• Maximum daily oral dose is 360 mg 1

Clinical Pearls

• If the patient is hemodynamically unstable, synchronized cardioversion is preferred over medication 1
• Diltiazem works by slowing AV node conduction and increasing AV node refractoriness 1, 5
• Always have resuscitation equipment available when administering IV diltiazem 1
• Monitor blood pressure and heart rate continuously during administration 1, 2