Can propofol cause bradycardia?

Propofol and Bradycardia: Clinical Implications

Yes, propofol can cause bradycardia, and caution is recommended when using propofol in patients with pre-existing bradyarrhythmias. 1 There is sufficient evidence that propofol has vagotonic effects that can lead to clinically significant bradycardia in certain patient populations.

Mechanism of Propofol-Induced Bradycardia

Propofol can cause bradycardia through several mechanisms:

• Vagotonic effects: Propofol lacks central vagolytic activity and may exert a central vagotonic effect 2
• HCN channel inhibition: Propofol inhibits hyperpolarization-activated cyclic nucleotide-gated (HCN) channels that contribute to cardiac autorhythmicity at clinically relevant concentrations 3
• Autonomic imbalance: Propofol reduces sympathetic tone to a greater degree than parasympathetic tone, creating an autonomic milieu that predisposes patients to bradycardia in response to parasympathetic stimuli 4
• Muscarinic receptor activation: Propofol may lead to bradycardia via muscarinic-receptor activation 2

Incidence and Risk Factors

The overall incidence of bradycardia (heart rate < 50 beats/min) with propofol is approximately 4.8%, with 42% of episodes occurring within the first 10 minutes after induction 5. In controlled clinical trials, propofol significantly increased the risk of bradycardia compared to other anesthetics, with a number-needed-to-harm of 11.3 6.

Risk factors for propofol-induced bradycardia include:

• Concomitant use of opioids (especially fentanyl) 7, 5
• Chronically taken beta-adrenergic receptor-blocking drugs 5
• Pediatric patients undergoing strabismus surgery (number-needed-to-harm: 4.1) 6
• Lack of anticholinergic premedication 2
• Use of succinylcholine after propofol 2

Clinical Implications and Management

Prevention:

• Consider premedication with anticholinergics (e.g., atropine) in high-risk patients 2
• The FDA label warns about administering propofol "with caution to patients with bradyarrhythmias" 7
• Consider alternative sedatives in patients with pre-existing bradycardia or cardiac conduction disorders

Monitoring:

• Continuous ECG monitoring is essential during propofol administration
• Pay particular attention during the first 10 minutes after induction when most bradycardic events occur 5

Treatment:

• For severe bradycardia: administer atropine or other anticholinergic agents
• In cases of atropine-refractory infra-nodal heart block with propofol, be aware that cardiogenic shock has been reported 1
• Consider dose reduction or discontinuation of propofol if significant bradycardia occurs

Special Considerations

Cardiac Patients:

• In patients with arrhythmias, propofol appears to have anti-arrhythmic effects for supraventricular arrhythmias and VT storm 1
• However, scattered reports of atropine-refractory infra-nodal heart block complicated by cardiogenic shock with propofol have questioned its safety during bradyarrhythmias 1
• According to the European Heart Journal, "There is insufficient evidence to contraindicate the use of propofol with bradyarrhythmias, but caution is recommended" 1

Pediatric Patients:

• Pediatric patients are particularly susceptible to bradycardia with propofol, especially when fentanyl is given concomitantly 7
• Consider prophylactic anticholinergic agents in pediatric patients receiving propofol and opioids

Conclusion

Propofol can cause bradycardia through multiple mechanisms, particularly in the early phase of administration. While this effect is usually manageable, it requires appropriate monitoring and preparation, especially in high-risk patients. The evidence suggests that while propofol-induced bradycardia is a real concern, it rarely leads to serious adverse outcomes when properly managed.