What is the dose of diltiazem (calcium channel blocker) for supraventricular tachycardia (SVT)?

Diltiazem Dosing for Supraventricular Tachycardia (SVT)

For SVT treatment, intravenous diltiazem should be administered at an initial dose of 0.25 mg/kg (approximately 15-20 mg for an average adult) over 2 minutes. 1

Initial Management Approach

• Adenosine is the first-line agent for stable SVT due to its rapid action and short half-life 1
• Diltiazem is an excellent second-line option when adenosine fails or is contraindicated 1
• Synchronized cardioversion should be performed immediately for hemodynamically unstable patients rather than medication administration 2, 1

IV Diltiazem Administration Protocol

• Initial dose: 0.25 mg/kg IV over 2 minutes 1, 3
• This dosing has been shown to be highly effective, with conversion rates of 100% in clinical studies 3
• If the initial dose is ineffective, a second dose of 0.35 mg/kg can be considered 4
• Following successful conversion, a maintenance infusion of 4 mg/kg/24 hours may be initiated 5

Efficacy of Diltiazem in SVT

• Intravenous diltiazem terminates SVT in 82-100% of patients at doses between 0.15-0.45 mg/kg 3
• Diltiazem works by slowing AV node conduction and increasing AV node refractoriness 1
• The median time to tachycardia termination is approximately 2 minutes after initiation of the infusion 4
• Diltiazem is particularly effective for AV nodal reentrant tachycardia (AVNRT), with 100% conversion rates reported 4

Contraindications and Cautions

• Avoid diltiazem 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
• Resuscitation equipment should always be available when administering IV diltiazem 1

Potential Adverse Effects

• Hypotension is the most common adverse effect, occurring in approximately 11% of patients 3
• Bradycardia may occur and should be monitored 1
• For severe bradycardia, consider atropine or temporary pacing if needed 1
• Overall, serious adverse effects are rare, with symptomatic hypotension reported in only 6% of patients 3

Oral Maintenance Therapy

• For long-term management after conversion, oral diltiazem can be used at 120 mg daily (divided or single dose with long-acting formulations) 1
• Maximum daily oral dose is 360 mg for long-term management 1
• Oral diltiazem has been shown to significantly decrease the frequency of recurrent SVT episodes 6
• Patients who respond to IV diltiazem are likely to respond to oral therapy as well 6

Special Considerations in Elderly Patients

• Diltiazem is effective and safe in elderly patients when used carefully 5
• Side effects in elderly patients (bradycardia, hypotension, cutaneous rash) typically resolve quickly after discontinuation 5
• Close monitoring is recommended when administering diltiazem to elderly patients with SVT 5