How to manage terbutaline-induced maternal bradycardia?

Management of Terbutaline-Induced Maternal Bradycardia

For terbutaline-induced maternal bradycardia, discontinue terbutaline immediately and position the mother in left lateral decubitus position; if symptoms persist, administer a cardioselective β-blocking agent such as metoprolol or consider temporary pacing for severe cases.

Pathophysiology and Clinical Presentation

Terbutaline is a β2-adrenergic agonist commonly used in obstetrics for tocolysis and treatment of fetal bradycardia. While it typically causes maternal tachycardia, paradoxical bradycardia can occur as an adverse effect.

• Mechanism: Though primarily a β2-agonist, terbutaline can occasionally trigger a vagal reflex or have direct effects on cardiac conduction, resulting in maternal bradycardia
• Clinical presentation may include:
  • Decreased maternal heart rate (usually <60 bpm)
  • Hypotension
  • Dizziness or lightheadedness
  • In severe cases: syncope or hemodynamic compromise

Management Algorithm

Immediate Management

1. Discontinue terbutaline administration immediately

2. Position change:

   • Place mother in left lateral decubitus position to improve venous return and cardiac output 1
   • This simple maneuver can resolve bradycardia in many cases, particularly when associated with supine hypotensive syndrome

3. Monitor vital signs:

   • Continuous heart rate monitoring
   • Blood pressure monitoring
   • Fetal heart rate monitoring (to ensure fetal well-being)

For Persistent Symptomatic Bradycardia

1. Pharmacological management:

   • For symptomatic bradycardia with hemodynamic compromise:
     • Administer a cardioselective β-blocking agent such as metoprolol 1
     • Alternatively, verapamil may be considered if β-blockers are contraindicated 1

2. For severe, refractory bradycardia:

   • Consider temporary pacemaker placement 1
   • This intervention should be reserved for cases with persistent symptoms despite other measures

Special Considerations

• Maternal monitoring: Continuous maternal heart rate, blood pressure, respiratory rate, and oxygen saturation
• Fetal monitoring: Continuous fetal heart rate monitoring is essential during management
• Avoid concurrent medications that may worsen bradycardia:
  • Calcium channel blockers (particularly when combined with magnesium sulfate) 2
  • Other β-agonists

Prevention Strategies

• Appropriate dosing: Use the lowest effective dose of terbutaline

• Patient selection: Exercise caution in patients with:

  • Pre-existing cardiac conditions
  • Conduction abnormalities
  • Concurrent use of medications that affect cardiac conduction

• Alternative tocolytics: Consider alternative agents if appropriate for the clinical situation

Follow-up Care

• Monitor maternal vital signs until completely stabilized
• Resume normal activities once heart rate and symptoms have normalized
• Document the adverse reaction for future reference
• Consider alternative tocolytic agents if needed in future pregnancies

Key Pitfalls to Avoid

• Delayed recognition: Bradycardia may be overlooked amid other clinical concerns; maintain vigilance with continuous monitoring
• Overtreatment: Asymptomatic bradycardia may not require aggressive intervention; treat based on symptoms and hemodynamic status
• Neglecting fetal status: While managing maternal bradycardia, continue to monitor fetal well-being
• Failure to discontinue terbutaline: The first step in management must be cessation of the causative agent

Remember that while bradyarrhythmias during pregnancy are generally rare and have favorable outcomes in the absence of underlying heart disease 1, prompt recognition and appropriate management are essential to prevent maternal and fetal complications.