What is the treatment for tachycardia that won't decrease blood pressure?

Treatment for Tachycardia Without Decreasing Blood Pressure

Beta-blockers, particularly cardioselective agents like metoprolol and esmolol, are the first-line treatment for tachycardia when blood pressure maintenance is important. 1, 2

Evaluation and Classification

First, determine the type of tachycardia and hemodynamic stability:

• Assess for signs of instability: systolic BP ≤90 mmHg, altered mental status, ischemic chest discomfort, acute heart failure
• Obtain 12-lead ECG to classify the tachycardia:
  • Narrow-complex (supraventricular) vs. wide-complex (ventricular)
  • Regular vs. irregular rhythm

Treatment Algorithm Based on Tachycardia Type

1. Stable Narrow-Complex Tachycardia

• First-line: IV beta-blockers

  • Metoprolol: 5 mg IV over 1-2 minutes, repeated up to maximum 15 mg 1
  • Esmolol: Loading dose 500 mcg/kg over 1 minute, followed by infusion of 50 mcg/kg/min, titrated up to 300 mcg/kg/min as needed 3

• Alternative if beta-blockers contraindicated:

  • Non-dihydropyridine calcium channel blockers (for SVT only, not for pre-excited AF/flutter)
  • Diltiazem: 15-20 mg (0.25 mg/kg) IV over 2 minutes 1

2. Stable Wide-Complex Tachycardia

• For monomorphic VT without heart failure/MI:

  • Procainamide: 20-50 mg/min until arrhythmia suppressed (max 17 mg/kg) 1

• For monomorphic VT with heart failure/MI:

  • Amiodarone: 150 mg IV over 10 minutes, followed by infusion 1

• For undifferentiated wide-complex tachycardia:

  • Adenosine: 6 mg rapid IV push (may help diagnose the rhythm) 1
  • Avoid verapamil/diltiazem (risk of hemodynamic collapse if VT) 2

3. Multifocal Atrial Tachycardia (MAT)

• First-line: Metoprolol 1, 4, 5
  • Particularly effective in MAT with conversion rates of 68-100% in studies
  • Can be used cautiously even in patients with pulmonary disease after correction of hypoxia 4, 5

Special Considerations

• For junctional tachycardia: Beta-blockers are first-line therapy 1

• For sinus tachycardia: Treat underlying cause; beta-blockers if symptomatic 1

• For atrial fibrillation/flutter: Beta-blockers for rate control; consider rhythm control with amiodarone if persistent 1, 2

Important Precautions

• Avoid beta-blockers in:

  • Decompensated heart failure
  • Severe bronchospasm
  • High-degree AV block
  • Cardiogenic shock

• Avoid calcium channel blockers in:

  • Heart failure with reduced ejection fraction
  • Pre-excited atrial fibrillation/flutter
  • Wide-complex tachycardias of uncertain origin

• Monitor for hypotension with all agents, but beta-blockers (especially cardioselective ones) are less likely to cause significant hypotension compared to calcium channel blockers 6, 7

Dosing Recommendations for Beta-Blockers

• Metoprolol: 5 mg IV over 1-2 minutes, repeated every 5 minutes to maximum 15 mg
• Esmolol: 500 mcg/kg loading dose over 1 minute, then 50-300 mcg/kg/min infusion
• Atenolol: 5 mg IV over 5 minutes, may repeat once after 10 minutes

Beta-blockers are particularly valuable in this scenario as they effectively reduce heart rate through AV nodal blockade while having minimal impact on blood pressure compared to other agents, especially when using cardioselective agents like metoprolol or esmolol 1, 7.