How to manage bradycardia (slow heart rate) in patients with dengue?

Management of Bradycardia in Dengue Patients

In patients with dengue-associated bradycardia, observation without specific treatment is recommended for asymptomatic patients, while symptomatic cases require prompt intervention with atropine as first-line therapy, followed by temporary pacing if medical management fails. 1, 2

Assessment and Classification

• Evaluate for symptoms of hemodynamic compromise:

  • Hypotension (systolic BP <90 mmHg)
  • Altered mental status
  • Chest pain
  • Shortness of breath
  • Dizziness or syncope

• Classify bradycardia in dengue patients:

  1. Asymptomatic bradycardia: Heart rate <60 bpm without symptoms
  2. Symptomatic bradycardia: Heart rate <50 bpm with symptoms or hemodynamic compromise

Management Algorithm

For Asymptomatic Bradycardia in Dengue

• Close monitoring without specific intervention
• Sinus bradycardia in dengue is often transient and benign
• Continue fluid management as per dengue protocol
• Avoid medications that can worsen bradycardia (beta-blockers, calcium channel blockers)
• Monitor for progression to symptomatic bradycardia

For Symptomatic Bradycardia in Dengue

First-Line Treatment:

• Atropine 0.5-1 mg IV (can be repeated every 3-5 minutes as needed, maximum total dose 3 mg) 2, 3
• Ensure adequate hydration status while avoiding fluid overload

If Bradycardia Persists After Atropine:

• Dopamine 5-20 mcg/kg/min IV infusion

  • Start at 5 mcg/kg/min
  • Increase by 5 mcg/kg/min every 2 minutes as needed 2

• Alternative agents:

  • Epinephrine: 2-10 mcg/min IV infusion 1
  • Isoproterenol: 2-10 mcg/min IV infusion (use with caution in patients with suspected myocarditis) 1

For Refractory Bradycardia:

• Temporary transcutaneous pacing for immediate management
• Consider temporary transvenous pacing if bradycardia is persistent and hemodynamically significant 1, 4

Special Considerations in Dengue

1. Myocardial Involvement: Dengue can cause myocarditis in up to 13% of severe cases, which may contribute to bradyarrhythmias 5

   • Obtain cardiac biomarkers (troponin, CK-MB) and echocardiography in patients with persistent bradycardia 6
   • Elevated cardiac biomarkers are associated with worse outcomes 6

2. Fluid Management: Balance carefully

   • Avoid aggressive fluid administration in patients with myocardial dysfunction
   • Monitor for signs of fluid overload (pulmonary edema)
   • Consider central venous pressure monitoring in severe cases

3. Electrolyte Monitoring:

   • Check and correct electrolyte imbalances (particularly potassium and calcium)
   • Electrolyte abnormalities can exacerbate conduction disturbances 7

4. ECG Monitoring:

   • Continuous cardiac monitoring is essential
   • Look for conduction abnormalities beyond bradycardia (AV blocks, ST-T changes) 5

Prognostic Implications

• Bradycardia in dengue may be a marker of myocardial involvement
• Patients with ECG abnormalities, echocardiographic changes, or elevated cardiac biomarkers have higher risk of adverse outcomes 6
• Most cardiac manifestations in dengue are transient and resolve with supportive care 5, 7

Pitfalls and Caveats

1. Do not use beta-blockers or calcium channel blockers to manage other symptoms in patients with dengue-associated bradycardia as these may worsen the condition 2

2. Do not place temporary pacemakers in patients with minimal symptoms and no hemodynamic compromise, as this carries unnecessary procedural risks 1

3. Do not assume all bradycardia in dengue is benign - evaluate for myocardial involvement in persistent cases 6, 7

4. Do not delay intervention in patients with symptomatic bradycardia as it can lead to cardiovascular collapse, especially in patients with dengue shock syndrome 8